ExprConstant.cpp revision 276479
1//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements the Expr constant evaluator. 11// 12// Constant expression evaluation produces four main results: 13// 14// * A success/failure flag indicating whether constant folding was successful. 15// This is the 'bool' return value used by most of the code in this file. A 16// 'false' return value indicates that constant folding has failed, and any 17// appropriate diagnostic has already been produced. 18// 19// * An evaluated result, valid only if constant folding has not failed. 20// 21// * A flag indicating if evaluation encountered (unevaluated) side-effects. 22// These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1), 23// where it is possible to determine the evaluated result regardless. 24// 25// * A set of notes indicating why the evaluation was not a constant expression 26// (under the C++11 / C++1y rules only, at the moment), or, if folding failed 27// too, why the expression could not be folded. 28// 29// If we are checking for a potential constant expression, failure to constant 30// fold a potential constant sub-expression will be indicated by a 'false' 31// return value (the expression could not be folded) and no diagnostic (the 32// expression is not necessarily non-constant). 33// 34//===----------------------------------------------------------------------===// 35 36#include "clang/AST/APValue.h" 37#include "clang/AST/ASTContext.h" 38#include "clang/AST/ASTDiagnostic.h" 39#include "clang/AST/CharUnits.h" 40#include "clang/AST/Expr.h" 41#include "clang/AST/RecordLayout.h" 42#include "clang/AST/StmtVisitor.h" 43#include "clang/AST/TypeLoc.h" 44#include "clang/Basic/Builtins.h" 45#include "clang/Basic/TargetInfo.h" 46#include "llvm/ADT/SmallString.h" 47#include "llvm/Support/raw_ostream.h" 48#include <cstring> 49#include <functional> 50 51using namespace clang; 52using llvm::APSInt; 53using llvm::APFloat; 54 55static bool IsGlobalLValue(APValue::LValueBase B); 56 57namespace { 58 struct LValue; 59 struct CallStackFrame; 60 struct EvalInfo; 61 62 static QualType getType(APValue::LValueBase B) { 63 if (!B) return QualType(); 64 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) 65 return D->getType(); 66 67 const Expr *Base = B.get<const Expr*>(); 68 69 // For a materialized temporary, the type of the temporary we materialized 70 // may not be the type of the expression. 71 if (const MaterializeTemporaryExpr *MTE = 72 dyn_cast<MaterializeTemporaryExpr>(Base)) { 73 SmallVector<const Expr *, 2> CommaLHSs; 74 SmallVector<SubobjectAdjustment, 2> Adjustments; 75 const Expr *Temp = MTE->GetTemporaryExpr(); 76 const Expr *Inner = Temp->skipRValueSubobjectAdjustments(CommaLHSs, 77 Adjustments); 78 // Keep any cv-qualifiers from the reference if we generated a temporary 79 // for it. 80 if (Inner != Temp) 81 return Inner->getType(); 82 } 83 84 return Base->getType(); 85 } 86 87 /// Get an LValue path entry, which is known to not be an array index, as a 88 /// field or base class. 89 static 90 APValue::BaseOrMemberType getAsBaseOrMember(APValue::LValuePathEntry E) { 91 APValue::BaseOrMemberType Value; 92 Value.setFromOpaqueValue(E.BaseOrMember); 93 return Value; 94 } 95 96 /// Get an LValue path entry, which is known to not be an array index, as a 97 /// field declaration. 98 static const FieldDecl *getAsField(APValue::LValuePathEntry E) { 99 return dyn_cast<FieldDecl>(getAsBaseOrMember(E).getPointer()); 100 } 101 /// Get an LValue path entry, which is known to not be an array index, as a 102 /// base class declaration. 103 static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) { 104 return dyn_cast<CXXRecordDecl>(getAsBaseOrMember(E).getPointer()); 105 } 106 /// Determine whether this LValue path entry for a base class names a virtual 107 /// base class. 108 static bool isVirtualBaseClass(APValue::LValuePathEntry E) { 109 return getAsBaseOrMember(E).getInt(); 110 } 111 112 /// Find the path length and type of the most-derived subobject in the given 113 /// path, and find the size of the containing array, if any. 114 static 115 unsigned findMostDerivedSubobject(ASTContext &Ctx, QualType Base, 116 ArrayRef<APValue::LValuePathEntry> Path, 117 uint64_t &ArraySize, QualType &Type) { 118 unsigned MostDerivedLength = 0; 119 Type = Base; 120 for (unsigned I = 0, N = Path.size(); I != N; ++I) { 121 if (Type->isArrayType()) { 122 const ConstantArrayType *CAT = 123 cast<ConstantArrayType>(Ctx.getAsArrayType(Type)); 124 Type = CAT->getElementType(); 125 ArraySize = CAT->getSize().getZExtValue(); 126 MostDerivedLength = I + 1; 127 } else if (Type->isAnyComplexType()) { 128 const ComplexType *CT = Type->castAs<ComplexType>(); 129 Type = CT->getElementType(); 130 ArraySize = 2; 131 MostDerivedLength = I + 1; 132 } else if (const FieldDecl *FD = getAsField(Path[I])) { 133 Type = FD->getType(); 134 ArraySize = 0; 135 MostDerivedLength = I + 1; 136 } else { 137 // Path[I] describes a base class. 138 ArraySize = 0; 139 } 140 } 141 return MostDerivedLength; 142 } 143 144 // The order of this enum is important for diagnostics. 145 enum CheckSubobjectKind { 146 CSK_Base, CSK_Derived, CSK_Field, CSK_ArrayToPointer, CSK_ArrayIndex, 147 CSK_This, CSK_Real, CSK_Imag 148 }; 149 150 /// A path from a glvalue to a subobject of that glvalue. 151 struct SubobjectDesignator { 152 /// True if the subobject was named in a manner not supported by C++11. Such 153 /// lvalues can still be folded, but they are not core constant expressions 154 /// and we cannot perform lvalue-to-rvalue conversions on them. 155 bool Invalid : 1; 156 157 /// Is this a pointer one past the end of an object? 158 bool IsOnePastTheEnd : 1; 159 160 /// The length of the path to the most-derived object of which this is a 161 /// subobject. 162 unsigned MostDerivedPathLength : 30; 163 164 /// The size of the array of which the most-derived object is an element, or 165 /// 0 if the most-derived object is not an array element. 166 uint64_t MostDerivedArraySize; 167 168 /// The type of the most derived object referred to by this address. 169 QualType MostDerivedType; 170 171 typedef APValue::LValuePathEntry PathEntry; 172 173 /// The entries on the path from the glvalue to the designated subobject. 174 SmallVector<PathEntry, 8> Entries; 175 176 SubobjectDesignator() : Invalid(true) {} 177 178 explicit SubobjectDesignator(QualType T) 179 : Invalid(false), IsOnePastTheEnd(false), MostDerivedPathLength(0), 180 MostDerivedArraySize(0), MostDerivedType(T) {} 181 182 SubobjectDesignator(ASTContext &Ctx, const APValue &V) 183 : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false), 184 MostDerivedPathLength(0), MostDerivedArraySize(0) { 185 if (!Invalid) { 186 IsOnePastTheEnd = V.isLValueOnePastTheEnd(); 187 ArrayRef<PathEntry> VEntries = V.getLValuePath(); 188 Entries.insert(Entries.end(), VEntries.begin(), VEntries.end()); 189 if (V.getLValueBase()) 190 MostDerivedPathLength = 191 findMostDerivedSubobject(Ctx, getType(V.getLValueBase()), 192 V.getLValuePath(), MostDerivedArraySize, 193 MostDerivedType); 194 } 195 } 196 197 void setInvalid() { 198 Invalid = true; 199 Entries.clear(); 200 } 201 202 /// Determine whether this is a one-past-the-end pointer. 203 bool isOnePastTheEnd() const { 204 if (IsOnePastTheEnd) 205 return true; 206 if (MostDerivedArraySize && 207 Entries[MostDerivedPathLength - 1].ArrayIndex == MostDerivedArraySize) 208 return true; 209 return false; 210 } 211 212 /// Check that this refers to a valid subobject. 213 bool isValidSubobject() const { 214 if (Invalid) 215 return false; 216 return !isOnePastTheEnd(); 217 } 218 /// Check that this refers to a valid subobject, and if not, produce a 219 /// relevant diagnostic and set the designator as invalid. 220 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK); 221 222 /// Update this designator to refer to the first element within this array. 223 void addArrayUnchecked(const ConstantArrayType *CAT) { 224 PathEntry Entry; 225 Entry.ArrayIndex = 0; 226 Entries.push_back(Entry); 227 228 // This is a most-derived object. 229 MostDerivedType = CAT->getElementType(); 230 MostDerivedArraySize = CAT->getSize().getZExtValue(); 231 MostDerivedPathLength = Entries.size(); 232 } 233 /// Update this designator to refer to the given base or member of this 234 /// object. 235 void addDeclUnchecked(const Decl *D, bool Virtual = false) { 236 PathEntry Entry; 237 APValue::BaseOrMemberType Value(D, Virtual); 238 Entry.BaseOrMember = Value.getOpaqueValue(); 239 Entries.push_back(Entry); 240 241 // If this isn't a base class, it's a new most-derived object. 242 if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) { 243 MostDerivedType = FD->getType(); 244 MostDerivedArraySize = 0; 245 MostDerivedPathLength = Entries.size(); 246 } 247 } 248 /// Update this designator to refer to the given complex component. 249 void addComplexUnchecked(QualType EltTy, bool Imag) { 250 PathEntry Entry; 251 Entry.ArrayIndex = Imag; 252 Entries.push_back(Entry); 253 254 // This is technically a most-derived object, though in practice this 255 // is unlikely to matter. 256 MostDerivedType = EltTy; 257 MostDerivedArraySize = 2; 258 MostDerivedPathLength = Entries.size(); 259 } 260 void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, uint64_t N); 261 /// Add N to the address of this subobject. 262 void adjustIndex(EvalInfo &Info, const Expr *E, uint64_t N) { 263 if (Invalid) return; 264 if (MostDerivedPathLength == Entries.size() && MostDerivedArraySize) { 265 Entries.back().ArrayIndex += N; 266 if (Entries.back().ArrayIndex > MostDerivedArraySize) { 267 diagnosePointerArithmetic(Info, E, Entries.back().ArrayIndex); 268 setInvalid(); 269 } 270 return; 271 } 272 // [expr.add]p4: For the purposes of these operators, a pointer to a 273 // nonarray object behaves the same as a pointer to the first element of 274 // an array of length one with the type of the object as its element type. 275 if (IsOnePastTheEnd && N == (uint64_t)-1) 276 IsOnePastTheEnd = false; 277 else if (!IsOnePastTheEnd && N == 1) 278 IsOnePastTheEnd = true; 279 else if (N != 0) { 280 diagnosePointerArithmetic(Info, E, uint64_t(IsOnePastTheEnd) + N); 281 setInvalid(); 282 } 283 } 284 }; 285 286 /// A stack frame in the constexpr call stack. 287 struct CallStackFrame { 288 EvalInfo &Info; 289 290 /// Parent - The caller of this stack frame. 291 CallStackFrame *Caller; 292 293 /// CallLoc - The location of the call expression for this call. 294 SourceLocation CallLoc; 295 296 /// Callee - The function which was called. 297 const FunctionDecl *Callee; 298 299 /// Index - The call index of this call. 300 unsigned Index; 301 302 /// This - The binding for the this pointer in this call, if any. 303 const LValue *This; 304 305 /// Arguments - Parameter bindings for this function call, indexed by 306 /// parameters' function scope indices. 307 APValue *Arguments; 308 309 // Note that we intentionally use std::map here so that references to 310 // values are stable. 311 typedef std::map<const void*, APValue> MapTy; 312 typedef MapTy::const_iterator temp_iterator; 313 /// Temporaries - Temporary lvalues materialized within this stack frame. 314 MapTy Temporaries; 315 316 CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, 317 const FunctionDecl *Callee, const LValue *This, 318 APValue *Arguments); 319 ~CallStackFrame(); 320 321 APValue *getTemporary(const void *Key) { 322 MapTy::iterator I = Temporaries.find(Key); 323 return I == Temporaries.end() ? nullptr : &I->second; 324 } 325 APValue &createTemporary(const void *Key, bool IsLifetimeExtended); 326 }; 327 328 /// Temporarily override 'this'. 329 class ThisOverrideRAII { 330 public: 331 ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable) 332 : Frame(Frame), OldThis(Frame.This) { 333 if (Enable) 334 Frame.This = NewThis; 335 } 336 ~ThisOverrideRAII() { 337 Frame.This = OldThis; 338 } 339 private: 340 CallStackFrame &Frame; 341 const LValue *OldThis; 342 }; 343 344 /// A partial diagnostic which we might know in advance that we are not going 345 /// to emit. 346 class OptionalDiagnostic { 347 PartialDiagnostic *Diag; 348 349 public: 350 explicit OptionalDiagnostic(PartialDiagnostic *Diag = nullptr) 351 : Diag(Diag) {} 352 353 template<typename T> 354 OptionalDiagnostic &operator<<(const T &v) { 355 if (Diag) 356 *Diag << v; 357 return *this; 358 } 359 360 OptionalDiagnostic &operator<<(const APSInt &I) { 361 if (Diag) { 362 SmallVector<char, 32> Buffer; 363 I.toString(Buffer); 364 *Diag << StringRef(Buffer.data(), Buffer.size()); 365 } 366 return *this; 367 } 368 369 OptionalDiagnostic &operator<<(const APFloat &F) { 370 if (Diag) { 371 // FIXME: Force the precision of the source value down so we don't 372 // print digits which are usually useless (we don't really care here if 373 // we truncate a digit by accident in edge cases). Ideally, 374 // APFloat::toString would automatically print the shortest 375 // representation which rounds to the correct value, but it's a bit 376 // tricky to implement. 377 unsigned precision = 378 llvm::APFloat::semanticsPrecision(F.getSemantics()); 379 precision = (precision * 59 + 195) / 196; 380 SmallVector<char, 32> Buffer; 381 F.toString(Buffer, precision); 382 *Diag << StringRef(Buffer.data(), Buffer.size()); 383 } 384 return *this; 385 } 386 }; 387 388 /// A cleanup, and a flag indicating whether it is lifetime-extended. 389 class Cleanup { 390 llvm::PointerIntPair<APValue*, 1, bool> Value; 391 392 public: 393 Cleanup(APValue *Val, bool IsLifetimeExtended) 394 : Value(Val, IsLifetimeExtended) {} 395 396 bool isLifetimeExtended() const { return Value.getInt(); } 397 void endLifetime() { 398 *Value.getPointer() = APValue(); 399 } 400 }; 401 402 /// EvalInfo - This is a private struct used by the evaluator to capture 403 /// information about a subexpression as it is folded. It retains information 404 /// about the AST context, but also maintains information about the folded 405 /// expression. 406 /// 407 /// If an expression could be evaluated, it is still possible it is not a C 408 /// "integer constant expression" or constant expression. If not, this struct 409 /// captures information about how and why not. 410 /// 411 /// One bit of information passed *into* the request for constant folding 412 /// indicates whether the subexpression is "evaluated" or not according to C 413 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can 414 /// evaluate the expression regardless of what the RHS is, but C only allows 415 /// certain things in certain situations. 416 struct EvalInfo { 417 ASTContext &Ctx; 418 419 /// EvalStatus - Contains information about the evaluation. 420 Expr::EvalStatus &EvalStatus; 421 422 /// CurrentCall - The top of the constexpr call stack. 423 CallStackFrame *CurrentCall; 424 425 /// CallStackDepth - The number of calls in the call stack right now. 426 unsigned CallStackDepth; 427 428 /// NextCallIndex - The next call index to assign. 429 unsigned NextCallIndex; 430 431 /// StepsLeft - The remaining number of evaluation steps we're permitted 432 /// to perform. This is essentially a limit for the number of statements 433 /// we will evaluate. 434 unsigned StepsLeft; 435 436 /// BottomFrame - The frame in which evaluation started. This must be 437 /// initialized after CurrentCall and CallStackDepth. 438 CallStackFrame BottomFrame; 439 440 /// A stack of values whose lifetimes end at the end of some surrounding 441 /// evaluation frame. 442 llvm::SmallVector<Cleanup, 16> CleanupStack; 443 444 /// EvaluatingDecl - This is the declaration whose initializer is being 445 /// evaluated, if any. 446 APValue::LValueBase EvaluatingDecl; 447 448 /// EvaluatingDeclValue - This is the value being constructed for the 449 /// declaration whose initializer is being evaluated, if any. 450 APValue *EvaluatingDeclValue; 451 452 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further 453 /// notes attached to it will also be stored, otherwise they will not be. 454 bool HasActiveDiagnostic; 455 456 enum EvaluationMode { 457 /// Evaluate as a constant expression. Stop if we find that the expression 458 /// is not a constant expression. 459 EM_ConstantExpression, 460 461 /// Evaluate as a potential constant expression. Keep going if we hit a 462 /// construct that we can't evaluate yet (because we don't yet know the 463 /// value of something) but stop if we hit something that could never be 464 /// a constant expression. 465 EM_PotentialConstantExpression, 466 467 /// Fold the expression to a constant. Stop if we hit a side-effect that 468 /// we can't model. 469 EM_ConstantFold, 470 471 /// Evaluate the expression looking for integer overflow and similar 472 /// issues. Don't worry about side-effects, and try to visit all 473 /// subexpressions. 474 EM_EvaluateForOverflow, 475 476 /// Evaluate in any way we know how. Don't worry about side-effects that 477 /// can't be modeled. 478 EM_IgnoreSideEffects, 479 480 /// Evaluate as a constant expression. Stop if we find that the expression 481 /// is not a constant expression. Some expressions can be retried in the 482 /// optimizer if we don't constant fold them here, but in an unevaluated 483 /// context we try to fold them immediately since the optimizer never 484 /// gets a chance to look at it. 485 EM_ConstantExpressionUnevaluated, 486 487 /// Evaluate as a potential constant expression. Keep going if we hit a 488 /// construct that we can't evaluate yet (because we don't yet know the 489 /// value of something) but stop if we hit something that could never be 490 /// a constant expression. Some expressions can be retried in the 491 /// optimizer if we don't constant fold them here, but in an unevaluated 492 /// context we try to fold them immediately since the optimizer never 493 /// gets a chance to look at it. 494 EM_PotentialConstantExpressionUnevaluated 495 } EvalMode; 496 497 /// Are we checking whether the expression is a potential constant 498 /// expression? 499 bool checkingPotentialConstantExpression() const { 500 return EvalMode == EM_PotentialConstantExpression || 501 EvalMode == EM_PotentialConstantExpressionUnevaluated; 502 } 503 504 /// Are we checking an expression for overflow? 505 // FIXME: We should check for any kind of undefined or suspicious behavior 506 // in such constructs, not just overflow. 507 bool checkingForOverflow() { return EvalMode == EM_EvaluateForOverflow; } 508 509 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode) 510 : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr), 511 CallStackDepth(0), NextCallIndex(1), 512 StepsLeft(getLangOpts().ConstexprStepLimit), 513 BottomFrame(*this, SourceLocation(), nullptr, nullptr, nullptr), 514 EvaluatingDecl((const ValueDecl *)nullptr), 515 EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false), 516 EvalMode(Mode) {} 517 518 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) { 519 EvaluatingDecl = Base; 520 EvaluatingDeclValue = &Value; 521 } 522 523 const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); } 524 525 bool CheckCallLimit(SourceLocation Loc) { 526 // Don't perform any constexpr calls (other than the call we're checking) 527 // when checking a potential constant expression. 528 if (checkingPotentialConstantExpression() && CallStackDepth > 1) 529 return false; 530 if (NextCallIndex == 0) { 531 // NextCallIndex has wrapped around. 532 Diag(Loc, diag::note_constexpr_call_limit_exceeded); 533 return false; 534 } 535 if (CallStackDepth <= getLangOpts().ConstexprCallDepth) 536 return true; 537 Diag(Loc, diag::note_constexpr_depth_limit_exceeded) 538 << getLangOpts().ConstexprCallDepth; 539 return false; 540 } 541 542 CallStackFrame *getCallFrame(unsigned CallIndex) { 543 assert(CallIndex && "no call index in getCallFrame"); 544 // We will eventually hit BottomFrame, which has Index 1, so Frame can't 545 // be null in this loop. 546 CallStackFrame *Frame = CurrentCall; 547 while (Frame->Index > CallIndex) 548 Frame = Frame->Caller; 549 return (Frame->Index == CallIndex) ? Frame : nullptr; 550 } 551 552 bool nextStep(const Stmt *S) { 553 if (!StepsLeft) { 554 Diag(S->getLocStart(), diag::note_constexpr_step_limit_exceeded); 555 return false; 556 } 557 --StepsLeft; 558 return true; 559 } 560 561 private: 562 /// Add a diagnostic to the diagnostics list. 563 PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId) { 564 PartialDiagnostic PD(DiagId, Ctx.getDiagAllocator()); 565 EvalStatus.Diag->push_back(std::make_pair(Loc, PD)); 566 return EvalStatus.Diag->back().second; 567 } 568 569 /// Add notes containing a call stack to the current point of evaluation. 570 void addCallStack(unsigned Limit); 571 572 public: 573 /// Diagnose that the evaluation cannot be folded. 574 OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId 575 = diag::note_invalid_subexpr_in_const_expr, 576 unsigned ExtraNotes = 0) { 577 if (EvalStatus.Diag) { 578 // If we have a prior diagnostic, it will be noting that the expression 579 // isn't a constant expression. This diagnostic is more important, 580 // unless we require this evaluation to produce a constant expression. 581 // 582 // FIXME: We might want to show both diagnostics to the user in 583 // EM_ConstantFold mode. 584 if (!EvalStatus.Diag->empty()) { 585 switch (EvalMode) { 586 case EM_ConstantFold: 587 case EM_IgnoreSideEffects: 588 case EM_EvaluateForOverflow: 589 if (!EvalStatus.HasSideEffects) 590 break; 591 // We've had side-effects; we want the diagnostic from them, not 592 // some later problem. 593 case EM_ConstantExpression: 594 case EM_PotentialConstantExpression: 595 case EM_ConstantExpressionUnevaluated: 596 case EM_PotentialConstantExpressionUnevaluated: 597 HasActiveDiagnostic = false; 598 return OptionalDiagnostic(); 599 } 600 } 601 602 unsigned CallStackNotes = CallStackDepth - 1; 603 unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit(); 604 if (Limit) 605 CallStackNotes = std::min(CallStackNotes, Limit + 1); 606 if (checkingPotentialConstantExpression()) 607 CallStackNotes = 0; 608 609 HasActiveDiagnostic = true; 610 EvalStatus.Diag->clear(); 611 EvalStatus.Diag->reserve(1 + ExtraNotes + CallStackNotes); 612 addDiag(Loc, DiagId); 613 if (!checkingPotentialConstantExpression()) 614 addCallStack(Limit); 615 return OptionalDiagnostic(&(*EvalStatus.Diag)[0].second); 616 } 617 HasActiveDiagnostic = false; 618 return OptionalDiagnostic(); 619 } 620 621 OptionalDiagnostic Diag(const Expr *E, diag::kind DiagId 622 = diag::note_invalid_subexpr_in_const_expr, 623 unsigned ExtraNotes = 0) { 624 if (EvalStatus.Diag) 625 return Diag(E->getExprLoc(), DiagId, ExtraNotes); 626 HasActiveDiagnostic = false; 627 return OptionalDiagnostic(); 628 } 629 630 /// Diagnose that the evaluation does not produce a C++11 core constant 631 /// expression. 632 /// 633 /// FIXME: Stop evaluating if we're in EM_ConstantExpression or 634 /// EM_PotentialConstantExpression mode and we produce one of these. 635 template<typename LocArg> 636 OptionalDiagnostic CCEDiag(LocArg Loc, diag::kind DiagId 637 = diag::note_invalid_subexpr_in_const_expr, 638 unsigned ExtraNotes = 0) { 639 // Don't override a previous diagnostic. Don't bother collecting 640 // diagnostics if we're evaluating for overflow. 641 if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) { 642 HasActiveDiagnostic = false; 643 return OptionalDiagnostic(); 644 } 645 return Diag(Loc, DiagId, ExtraNotes); 646 } 647 648 /// Add a note to a prior diagnostic. 649 OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId) { 650 if (!HasActiveDiagnostic) 651 return OptionalDiagnostic(); 652 return OptionalDiagnostic(&addDiag(Loc, DiagId)); 653 } 654 655 /// Add a stack of notes to a prior diagnostic. 656 void addNotes(ArrayRef<PartialDiagnosticAt> Diags) { 657 if (HasActiveDiagnostic) { 658 EvalStatus.Diag->insert(EvalStatus.Diag->end(), 659 Diags.begin(), Diags.end()); 660 } 661 } 662 663 /// Should we continue evaluation after encountering a side-effect that we 664 /// couldn't model? 665 bool keepEvaluatingAfterSideEffect() { 666 switch (EvalMode) { 667 case EM_PotentialConstantExpression: 668 case EM_PotentialConstantExpressionUnevaluated: 669 case EM_EvaluateForOverflow: 670 case EM_IgnoreSideEffects: 671 return true; 672 673 case EM_ConstantExpression: 674 case EM_ConstantExpressionUnevaluated: 675 case EM_ConstantFold: 676 return false; 677 } 678 llvm_unreachable("Missed EvalMode case"); 679 } 680 681 /// Note that we have had a side-effect, and determine whether we should 682 /// keep evaluating. 683 bool noteSideEffect() { 684 EvalStatus.HasSideEffects = true; 685 return keepEvaluatingAfterSideEffect(); 686 } 687 688 /// Should we continue evaluation as much as possible after encountering a 689 /// construct which can't be reduced to a value? 690 bool keepEvaluatingAfterFailure() { 691 if (!StepsLeft) 692 return false; 693 694 switch (EvalMode) { 695 case EM_PotentialConstantExpression: 696 case EM_PotentialConstantExpressionUnevaluated: 697 case EM_EvaluateForOverflow: 698 return true; 699 700 case EM_ConstantExpression: 701 case EM_ConstantExpressionUnevaluated: 702 case EM_ConstantFold: 703 case EM_IgnoreSideEffects: 704 return false; 705 } 706 llvm_unreachable("Missed EvalMode case"); 707 } 708 }; 709 710 /// Object used to treat all foldable expressions as constant expressions. 711 struct FoldConstant { 712 EvalInfo &Info; 713 bool Enabled; 714 bool HadNoPriorDiags; 715 EvalInfo::EvaluationMode OldMode; 716 717 explicit FoldConstant(EvalInfo &Info, bool Enabled) 718 : Info(Info), 719 Enabled(Enabled), 720 HadNoPriorDiags(Info.EvalStatus.Diag && 721 Info.EvalStatus.Diag->empty() && 722 !Info.EvalStatus.HasSideEffects), 723 OldMode(Info.EvalMode) { 724 if (Enabled && 725 (Info.EvalMode == EvalInfo::EM_ConstantExpression || 726 Info.EvalMode == EvalInfo::EM_ConstantExpressionUnevaluated)) 727 Info.EvalMode = EvalInfo::EM_ConstantFold; 728 } 729 void keepDiagnostics() { Enabled = false; } 730 ~FoldConstant() { 731 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() && 732 !Info.EvalStatus.HasSideEffects) 733 Info.EvalStatus.Diag->clear(); 734 Info.EvalMode = OldMode; 735 } 736 }; 737 738 /// RAII object used to suppress diagnostics and side-effects from a 739 /// speculative evaluation. 740 class SpeculativeEvaluationRAII { 741 EvalInfo &Info; 742 Expr::EvalStatus Old; 743 744 public: 745 SpeculativeEvaluationRAII(EvalInfo &Info, 746 SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr) 747 : Info(Info), Old(Info.EvalStatus) { 748 Info.EvalStatus.Diag = NewDiag; 749 // If we're speculatively evaluating, we may have skipped over some 750 // evaluations and missed out a side effect. 751 Info.EvalStatus.HasSideEffects = true; 752 } 753 ~SpeculativeEvaluationRAII() { 754 Info.EvalStatus = Old; 755 } 756 }; 757 758 /// RAII object wrapping a full-expression or block scope, and handling 759 /// the ending of the lifetime of temporaries created within it. 760 template<bool IsFullExpression> 761 class ScopeRAII { 762 EvalInfo &Info; 763 unsigned OldStackSize; 764 public: 765 ScopeRAII(EvalInfo &Info) 766 : Info(Info), OldStackSize(Info.CleanupStack.size()) {} 767 ~ScopeRAII() { 768 // Body moved to a static method to encourage the compiler to inline away 769 // instances of this class. 770 cleanup(Info, OldStackSize); 771 } 772 private: 773 static void cleanup(EvalInfo &Info, unsigned OldStackSize) { 774 unsigned NewEnd = OldStackSize; 775 for (unsigned I = OldStackSize, N = Info.CleanupStack.size(); 776 I != N; ++I) { 777 if (IsFullExpression && Info.CleanupStack[I].isLifetimeExtended()) { 778 // Full-expression cleanup of a lifetime-extended temporary: nothing 779 // to do, just move this cleanup to the right place in the stack. 780 std::swap(Info.CleanupStack[I], Info.CleanupStack[NewEnd]); 781 ++NewEnd; 782 } else { 783 // End the lifetime of the object. 784 Info.CleanupStack[I].endLifetime(); 785 } 786 } 787 Info.CleanupStack.erase(Info.CleanupStack.begin() + NewEnd, 788 Info.CleanupStack.end()); 789 } 790 }; 791 typedef ScopeRAII<false> BlockScopeRAII; 792 typedef ScopeRAII<true> FullExpressionRAII; 793} 794 795bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E, 796 CheckSubobjectKind CSK) { 797 if (Invalid) 798 return false; 799 if (isOnePastTheEnd()) { 800 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject) 801 << CSK; 802 setInvalid(); 803 return false; 804 } 805 return true; 806} 807 808void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info, 809 const Expr *E, uint64_t N) { 810 if (MostDerivedPathLength == Entries.size() && MostDerivedArraySize) 811 Info.CCEDiag(E, diag::note_constexpr_array_index) 812 << static_cast<int>(N) << /*array*/ 0 813 << static_cast<unsigned>(MostDerivedArraySize); 814 else 815 Info.CCEDiag(E, diag::note_constexpr_array_index) 816 << static_cast<int>(N) << /*non-array*/ 1; 817 setInvalid(); 818} 819 820CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, 821 const FunctionDecl *Callee, const LValue *This, 822 APValue *Arguments) 823 : Info(Info), Caller(Info.CurrentCall), CallLoc(CallLoc), Callee(Callee), 824 Index(Info.NextCallIndex++), This(This), Arguments(Arguments) { 825 Info.CurrentCall = this; 826 ++Info.CallStackDepth; 827} 828 829CallStackFrame::~CallStackFrame() { 830 assert(Info.CurrentCall == this && "calls retired out of order"); 831 --Info.CallStackDepth; 832 Info.CurrentCall = Caller; 833} 834 835APValue &CallStackFrame::createTemporary(const void *Key, 836 bool IsLifetimeExtended) { 837 APValue &Result = Temporaries[Key]; 838 assert(Result.isUninit() && "temporary created multiple times"); 839 Info.CleanupStack.push_back(Cleanup(&Result, IsLifetimeExtended)); 840 return Result; 841} 842 843static void describeCall(CallStackFrame *Frame, raw_ostream &Out); 844 845void EvalInfo::addCallStack(unsigned Limit) { 846 // Determine which calls to skip, if any. 847 unsigned ActiveCalls = CallStackDepth - 1; 848 unsigned SkipStart = ActiveCalls, SkipEnd = SkipStart; 849 if (Limit && Limit < ActiveCalls) { 850 SkipStart = Limit / 2 + Limit % 2; 851 SkipEnd = ActiveCalls - Limit / 2; 852 } 853 854 // Walk the call stack and add the diagnostics. 855 unsigned CallIdx = 0; 856 for (CallStackFrame *Frame = CurrentCall; Frame != &BottomFrame; 857 Frame = Frame->Caller, ++CallIdx) { 858 // Skip this call? 859 if (CallIdx >= SkipStart && CallIdx < SkipEnd) { 860 if (CallIdx == SkipStart) { 861 // Note that we're skipping calls. 862 addDiag(Frame->CallLoc, diag::note_constexpr_calls_suppressed) 863 << unsigned(ActiveCalls - Limit); 864 } 865 continue; 866 } 867 868 SmallVector<char, 128> Buffer; 869 llvm::raw_svector_ostream Out(Buffer); 870 describeCall(Frame, Out); 871 addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str(); 872 } 873} 874 875namespace { 876 struct ComplexValue { 877 private: 878 bool IsInt; 879 880 public: 881 APSInt IntReal, IntImag; 882 APFloat FloatReal, FloatImag; 883 884 ComplexValue() : FloatReal(APFloat::Bogus), FloatImag(APFloat::Bogus) {} 885 886 void makeComplexFloat() { IsInt = false; } 887 bool isComplexFloat() const { return !IsInt; } 888 APFloat &getComplexFloatReal() { return FloatReal; } 889 APFloat &getComplexFloatImag() { return FloatImag; } 890 891 void makeComplexInt() { IsInt = true; } 892 bool isComplexInt() const { return IsInt; } 893 APSInt &getComplexIntReal() { return IntReal; } 894 APSInt &getComplexIntImag() { return IntImag; } 895 896 void moveInto(APValue &v) const { 897 if (isComplexFloat()) 898 v = APValue(FloatReal, FloatImag); 899 else 900 v = APValue(IntReal, IntImag); 901 } 902 void setFrom(const APValue &v) { 903 assert(v.isComplexFloat() || v.isComplexInt()); 904 if (v.isComplexFloat()) { 905 makeComplexFloat(); 906 FloatReal = v.getComplexFloatReal(); 907 FloatImag = v.getComplexFloatImag(); 908 } else { 909 makeComplexInt(); 910 IntReal = v.getComplexIntReal(); 911 IntImag = v.getComplexIntImag(); 912 } 913 } 914 }; 915 916 struct LValue { 917 APValue::LValueBase Base; 918 CharUnits Offset; 919 unsigned CallIndex; 920 SubobjectDesignator Designator; 921 922 const APValue::LValueBase getLValueBase() const { return Base; } 923 CharUnits &getLValueOffset() { return Offset; } 924 const CharUnits &getLValueOffset() const { return Offset; } 925 unsigned getLValueCallIndex() const { return CallIndex; } 926 SubobjectDesignator &getLValueDesignator() { return Designator; } 927 const SubobjectDesignator &getLValueDesignator() const { return Designator;} 928 929 void moveInto(APValue &V) const { 930 if (Designator.Invalid) 931 V = APValue(Base, Offset, APValue::NoLValuePath(), CallIndex); 932 else 933 V = APValue(Base, Offset, Designator.Entries, 934 Designator.IsOnePastTheEnd, CallIndex); 935 } 936 void setFrom(ASTContext &Ctx, const APValue &V) { 937 assert(V.isLValue()); 938 Base = V.getLValueBase(); 939 Offset = V.getLValueOffset(); 940 CallIndex = V.getLValueCallIndex(); 941 Designator = SubobjectDesignator(Ctx, V); 942 } 943 944 void set(APValue::LValueBase B, unsigned I = 0) { 945 Base = B; 946 Offset = CharUnits::Zero(); 947 CallIndex = I; 948 Designator = SubobjectDesignator(getType(B)); 949 } 950 951 // Check that this LValue is not based on a null pointer. If it is, produce 952 // a diagnostic and mark the designator as invalid. 953 bool checkNullPointer(EvalInfo &Info, const Expr *E, 954 CheckSubobjectKind CSK) { 955 if (Designator.Invalid) 956 return false; 957 if (!Base) { 958 Info.CCEDiag(E, diag::note_constexpr_null_subobject) 959 << CSK; 960 Designator.setInvalid(); 961 return false; 962 } 963 return true; 964 } 965 966 // Check this LValue refers to an object. If not, set the designator to be 967 // invalid and emit a diagnostic. 968 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { 969 // Outside C++11, do not build a designator referring to a subobject of 970 // any object: we won't use such a designator for anything. 971 if (!Info.getLangOpts().CPlusPlus11) 972 Designator.setInvalid(); 973 return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) && 974 Designator.checkSubobject(Info, E, CSK); 975 } 976 977 void addDecl(EvalInfo &Info, const Expr *E, 978 const Decl *D, bool Virtual = false) { 979 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base)) 980 Designator.addDeclUnchecked(D, Virtual); 981 } 982 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) { 983 if (checkSubobject(Info, E, CSK_ArrayToPointer)) 984 Designator.addArrayUnchecked(CAT); 985 } 986 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) { 987 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real)) 988 Designator.addComplexUnchecked(EltTy, Imag); 989 } 990 void adjustIndex(EvalInfo &Info, const Expr *E, uint64_t N) { 991 if (N && checkNullPointer(Info, E, CSK_ArrayIndex)) 992 Designator.adjustIndex(Info, E, N); 993 } 994 }; 995 996 struct MemberPtr { 997 MemberPtr() {} 998 explicit MemberPtr(const ValueDecl *Decl) : 999 DeclAndIsDerivedMember(Decl, false), Path() {} 1000 1001 /// The member or (direct or indirect) field referred to by this member 1002 /// pointer, or 0 if this is a null member pointer. 1003 const ValueDecl *getDecl() const { 1004 return DeclAndIsDerivedMember.getPointer(); 1005 } 1006 /// Is this actually a member of some type derived from the relevant class? 1007 bool isDerivedMember() const { 1008 return DeclAndIsDerivedMember.getInt(); 1009 } 1010 /// Get the class which the declaration actually lives in. 1011 const CXXRecordDecl *getContainingRecord() const { 1012 return cast<CXXRecordDecl>( 1013 DeclAndIsDerivedMember.getPointer()->getDeclContext()); 1014 } 1015 1016 void moveInto(APValue &V) const { 1017 V = APValue(getDecl(), isDerivedMember(), Path); 1018 } 1019 void setFrom(const APValue &V) { 1020 assert(V.isMemberPointer()); 1021 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl()); 1022 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember()); 1023 Path.clear(); 1024 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath(); 1025 Path.insert(Path.end(), P.begin(), P.end()); 1026 } 1027 1028 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating 1029 /// whether the member is a member of some class derived from the class type 1030 /// of the member pointer. 1031 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember; 1032 /// Path - The path of base/derived classes from the member declaration's 1033 /// class (exclusive) to the class type of the member pointer (inclusive). 1034 SmallVector<const CXXRecordDecl*, 4> Path; 1035 1036 /// Perform a cast towards the class of the Decl (either up or down the 1037 /// hierarchy). 1038 bool castBack(const CXXRecordDecl *Class) { 1039 assert(!Path.empty()); 1040 const CXXRecordDecl *Expected; 1041 if (Path.size() >= 2) 1042 Expected = Path[Path.size() - 2]; 1043 else 1044 Expected = getContainingRecord(); 1045 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) { 1046 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*), 1047 // if B does not contain the original member and is not a base or 1048 // derived class of the class containing the original member, the result 1049 // of the cast is undefined. 1050 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to 1051 // (D::*). We consider that to be a language defect. 1052 return false; 1053 } 1054 Path.pop_back(); 1055 return true; 1056 } 1057 /// Perform a base-to-derived member pointer cast. 1058 bool castToDerived(const CXXRecordDecl *Derived) { 1059 if (!getDecl()) 1060 return true; 1061 if (!isDerivedMember()) { 1062 Path.push_back(Derived); 1063 return true; 1064 } 1065 if (!castBack(Derived)) 1066 return false; 1067 if (Path.empty()) 1068 DeclAndIsDerivedMember.setInt(false); 1069 return true; 1070 } 1071 /// Perform a derived-to-base member pointer cast. 1072 bool castToBase(const CXXRecordDecl *Base) { 1073 if (!getDecl()) 1074 return true; 1075 if (Path.empty()) 1076 DeclAndIsDerivedMember.setInt(true); 1077 if (isDerivedMember()) { 1078 Path.push_back(Base); 1079 return true; 1080 } 1081 return castBack(Base); 1082 } 1083 }; 1084 1085 /// Compare two member pointers, which are assumed to be of the same type. 1086 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) { 1087 if (!LHS.getDecl() || !RHS.getDecl()) 1088 return !LHS.getDecl() && !RHS.getDecl(); 1089 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl()) 1090 return false; 1091 return LHS.Path == RHS.Path; 1092 } 1093} 1094 1095static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E); 1096static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, 1097 const LValue &This, const Expr *E, 1098 bool AllowNonLiteralTypes = false); 1099static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info); 1100static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info); 1101static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, 1102 EvalInfo &Info); 1103static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info); 1104static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info); 1105static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, 1106 EvalInfo &Info); 1107static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info); 1108static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info); 1109static bool EvaluateAtomic(const Expr *E, APValue &Result, EvalInfo &Info); 1110 1111//===----------------------------------------------------------------------===// 1112// Misc utilities 1113//===----------------------------------------------------------------------===// 1114 1115/// Produce a string describing the given constexpr call. 1116static void describeCall(CallStackFrame *Frame, raw_ostream &Out) { 1117 unsigned ArgIndex = 0; 1118 bool IsMemberCall = isa<CXXMethodDecl>(Frame->Callee) && 1119 !isa<CXXConstructorDecl>(Frame->Callee) && 1120 cast<CXXMethodDecl>(Frame->Callee)->isInstance(); 1121 1122 if (!IsMemberCall) 1123 Out << *Frame->Callee << '('; 1124 1125 if (Frame->This && IsMemberCall) { 1126 APValue Val; 1127 Frame->This->moveInto(Val); 1128 Val.printPretty(Out, Frame->Info.Ctx, 1129 Frame->This->Designator.MostDerivedType); 1130 // FIXME: Add parens around Val if needed. 1131 Out << "->" << *Frame->Callee << '('; 1132 IsMemberCall = false; 1133 } 1134 1135 for (FunctionDecl::param_const_iterator I = Frame->Callee->param_begin(), 1136 E = Frame->Callee->param_end(); I != E; ++I, ++ArgIndex) { 1137 if (ArgIndex > (unsigned)IsMemberCall) 1138 Out << ", "; 1139 1140 const ParmVarDecl *Param = *I; 1141 const APValue &Arg = Frame->Arguments[ArgIndex]; 1142 Arg.printPretty(Out, Frame->Info.Ctx, Param->getType()); 1143 1144 if (ArgIndex == 0 && IsMemberCall) 1145 Out << "->" << *Frame->Callee << '('; 1146 } 1147 1148 Out << ')'; 1149} 1150 1151/// Evaluate an expression to see if it had side-effects, and discard its 1152/// result. 1153/// \return \c true if the caller should keep evaluating. 1154static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) { 1155 APValue Scratch; 1156 if (!Evaluate(Scratch, Info, E)) 1157 // We don't need the value, but we might have skipped a side effect here. 1158 return Info.noteSideEffect(); 1159 return true; 1160} 1161 1162/// Sign- or zero-extend a value to 64 bits. If it's already 64 bits, just 1163/// return its existing value. 1164static int64_t getExtValue(const APSInt &Value) { 1165 return Value.isSigned() ? Value.getSExtValue() 1166 : static_cast<int64_t>(Value.getZExtValue()); 1167} 1168 1169/// Should this call expression be treated as a string literal? 1170static bool IsStringLiteralCall(const CallExpr *E) { 1171 unsigned Builtin = E->getBuiltinCallee(); 1172 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString || 1173 Builtin == Builtin::BI__builtin___NSStringMakeConstantString); 1174} 1175 1176static bool IsGlobalLValue(APValue::LValueBase B) { 1177 // C++11 [expr.const]p3 An address constant expression is a prvalue core 1178 // constant expression of pointer type that evaluates to... 1179 1180 // ... a null pointer value, or a prvalue core constant expression of type 1181 // std::nullptr_t. 1182 if (!B) return true; 1183 1184 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { 1185 // ... the address of an object with static storage duration, 1186 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 1187 return VD->hasGlobalStorage(); 1188 // ... the address of a function, 1189 return isa<FunctionDecl>(D); 1190 } 1191 1192 const Expr *E = B.get<const Expr*>(); 1193 switch (E->getStmtClass()) { 1194 default: 1195 return false; 1196 case Expr::CompoundLiteralExprClass: { 1197 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 1198 return CLE->isFileScope() && CLE->isLValue(); 1199 } 1200 case Expr::MaterializeTemporaryExprClass: 1201 // A materialized temporary might have been lifetime-extended to static 1202 // storage duration. 1203 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static; 1204 // A string literal has static storage duration. 1205 case Expr::StringLiteralClass: 1206 case Expr::PredefinedExprClass: 1207 case Expr::ObjCStringLiteralClass: 1208 case Expr::ObjCEncodeExprClass: 1209 case Expr::CXXTypeidExprClass: 1210 case Expr::CXXUuidofExprClass: 1211 return true; 1212 case Expr::CallExprClass: 1213 return IsStringLiteralCall(cast<CallExpr>(E)); 1214 // For GCC compatibility, &&label has static storage duration. 1215 case Expr::AddrLabelExprClass: 1216 return true; 1217 // A Block literal expression may be used as the initialization value for 1218 // Block variables at global or local static scope. 1219 case Expr::BlockExprClass: 1220 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures(); 1221 case Expr::ImplicitValueInitExprClass: 1222 // FIXME: 1223 // We can never form an lvalue with an implicit value initialization as its 1224 // base through expression evaluation, so these only appear in one case: the 1225 // implicit variable declaration we invent when checking whether a constexpr 1226 // constructor can produce a constant expression. We must assume that such 1227 // an expression might be a global lvalue. 1228 return true; 1229 } 1230} 1231 1232static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) { 1233 assert(Base && "no location for a null lvalue"); 1234 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 1235 if (VD) 1236 Info.Note(VD->getLocation(), diag::note_declared_at); 1237 else 1238 Info.Note(Base.get<const Expr*>()->getExprLoc(), 1239 diag::note_constexpr_temporary_here); 1240} 1241 1242/// Check that this reference or pointer core constant expression is a valid 1243/// value for an address or reference constant expression. Return true if we 1244/// can fold this expression, whether or not it's a constant expression. 1245static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc, 1246 QualType Type, const LValue &LVal) { 1247 bool IsReferenceType = Type->isReferenceType(); 1248 1249 APValue::LValueBase Base = LVal.getLValueBase(); 1250 const SubobjectDesignator &Designator = LVal.getLValueDesignator(); 1251 1252 // Check that the object is a global. Note that the fake 'this' object we 1253 // manufacture when checking potential constant expressions is conservatively 1254 // assumed to be global here. 1255 if (!IsGlobalLValue(Base)) { 1256 if (Info.getLangOpts().CPlusPlus11) { 1257 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 1258 Info.Diag(Loc, diag::note_constexpr_non_global, 1) 1259 << IsReferenceType << !Designator.Entries.empty() 1260 << !!VD << VD; 1261 NoteLValueLocation(Info, Base); 1262 } else { 1263 Info.Diag(Loc); 1264 } 1265 // Don't allow references to temporaries to escape. 1266 return false; 1267 } 1268 assert((Info.checkingPotentialConstantExpression() || 1269 LVal.getLValueCallIndex() == 0) && 1270 "have call index for global lvalue"); 1271 1272 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) { 1273 if (const VarDecl *Var = dyn_cast<const VarDecl>(VD)) { 1274 // Check if this is a thread-local variable. 1275 if (Var->getTLSKind()) 1276 return false; 1277 1278 // A dllimport variable never acts like a constant. 1279 if (Var->hasAttr<DLLImportAttr>()) 1280 return false; 1281 } 1282 if (const auto *FD = dyn_cast<const FunctionDecl>(VD)) { 1283 // __declspec(dllimport) must be handled very carefully: 1284 // We must never initialize an expression with the thunk in C++. 1285 // Doing otherwise would allow the same id-expression to yield 1286 // different addresses for the same function in different translation 1287 // units. However, this means that we must dynamically initialize the 1288 // expression with the contents of the import address table at runtime. 1289 // 1290 // The C language has no notion of ODR; furthermore, it has no notion of 1291 // dynamic initialization. This means that we are permitted to 1292 // perform initialization with the address of the thunk. 1293 if (Info.getLangOpts().CPlusPlus && FD->hasAttr<DLLImportAttr>()) 1294 return false; 1295 } 1296 } 1297 1298 // Allow address constant expressions to be past-the-end pointers. This is 1299 // an extension: the standard requires them to point to an object. 1300 if (!IsReferenceType) 1301 return true; 1302 1303 // A reference constant expression must refer to an object. 1304 if (!Base) { 1305 // FIXME: diagnostic 1306 Info.CCEDiag(Loc); 1307 return true; 1308 } 1309 1310 // Does this refer one past the end of some object? 1311 if (Designator.isOnePastTheEnd()) { 1312 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 1313 Info.Diag(Loc, diag::note_constexpr_past_end, 1) 1314 << !Designator.Entries.empty() << !!VD << VD; 1315 NoteLValueLocation(Info, Base); 1316 } 1317 1318 return true; 1319} 1320 1321/// Check that this core constant expression is of literal type, and if not, 1322/// produce an appropriate diagnostic. 1323static bool CheckLiteralType(EvalInfo &Info, const Expr *E, 1324 const LValue *This = nullptr) { 1325 if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx)) 1326 return true; 1327 1328 // C++1y: A constant initializer for an object o [...] may also invoke 1329 // constexpr constructors for o and its subobjects even if those objects 1330 // are of non-literal class types. 1331 if (Info.getLangOpts().CPlusPlus1y && This && 1332 Info.EvaluatingDecl == This->getLValueBase()) 1333 return true; 1334 1335 // Prvalue constant expressions must be of literal types. 1336 if (Info.getLangOpts().CPlusPlus11) 1337 Info.Diag(E, diag::note_constexpr_nonliteral) 1338 << E->getType(); 1339 else 1340 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1341 return false; 1342} 1343 1344/// Check that this core constant expression value is a valid value for a 1345/// constant expression. If not, report an appropriate diagnostic. Does not 1346/// check that the expression is of literal type. 1347static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, 1348 QualType Type, const APValue &Value) { 1349 if (Value.isUninit()) { 1350 Info.Diag(DiagLoc, diag::note_constexpr_uninitialized) 1351 << true << Type; 1352 return false; 1353 } 1354 1355 // We allow _Atomic(T) to be initialized from anything that T can be 1356 // initialized from. 1357 if (const AtomicType *AT = Type->getAs<AtomicType>()) 1358 Type = AT->getValueType(); 1359 1360 // Core issue 1454: For a literal constant expression of array or class type, 1361 // each subobject of its value shall have been initialized by a constant 1362 // expression. 1363 if (Value.isArray()) { 1364 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType(); 1365 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) { 1366 if (!CheckConstantExpression(Info, DiagLoc, EltTy, 1367 Value.getArrayInitializedElt(I))) 1368 return false; 1369 } 1370 if (!Value.hasArrayFiller()) 1371 return true; 1372 return CheckConstantExpression(Info, DiagLoc, EltTy, 1373 Value.getArrayFiller()); 1374 } 1375 if (Value.isUnion() && Value.getUnionField()) { 1376 return CheckConstantExpression(Info, DiagLoc, 1377 Value.getUnionField()->getType(), 1378 Value.getUnionValue()); 1379 } 1380 if (Value.isStruct()) { 1381 RecordDecl *RD = Type->castAs<RecordType>()->getDecl(); 1382 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) { 1383 unsigned BaseIndex = 0; 1384 for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), 1385 End = CD->bases_end(); I != End; ++I, ++BaseIndex) { 1386 if (!CheckConstantExpression(Info, DiagLoc, I->getType(), 1387 Value.getStructBase(BaseIndex))) 1388 return false; 1389 } 1390 } 1391 for (const auto *I : RD->fields()) { 1392 if (!CheckConstantExpression(Info, DiagLoc, I->getType(), 1393 Value.getStructField(I->getFieldIndex()))) 1394 return false; 1395 } 1396 } 1397 1398 if (Value.isLValue()) { 1399 LValue LVal; 1400 LVal.setFrom(Info.Ctx, Value); 1401 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal); 1402 } 1403 1404 // Everything else is fine. 1405 return true; 1406} 1407 1408const ValueDecl *GetLValueBaseDecl(const LValue &LVal) { 1409 return LVal.Base.dyn_cast<const ValueDecl*>(); 1410} 1411 1412static bool IsLiteralLValue(const LValue &Value) { 1413 if (Value.CallIndex) 1414 return false; 1415 const Expr *E = Value.Base.dyn_cast<const Expr*>(); 1416 return E && !isa<MaterializeTemporaryExpr>(E); 1417} 1418 1419static bool IsWeakLValue(const LValue &Value) { 1420 const ValueDecl *Decl = GetLValueBaseDecl(Value); 1421 return Decl && Decl->isWeak(); 1422} 1423 1424static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) { 1425 // A null base expression indicates a null pointer. These are always 1426 // evaluatable, and they are false unless the offset is zero. 1427 if (!Value.getLValueBase()) { 1428 Result = !Value.getLValueOffset().isZero(); 1429 return true; 1430 } 1431 1432 // We have a non-null base. These are generally known to be true, but if it's 1433 // a weak declaration it can be null at runtime. 1434 Result = true; 1435 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>(); 1436 return !Decl || !Decl->isWeak(); 1437} 1438 1439static bool HandleConversionToBool(const APValue &Val, bool &Result) { 1440 switch (Val.getKind()) { 1441 case APValue::Uninitialized: 1442 return false; 1443 case APValue::Int: 1444 Result = Val.getInt().getBoolValue(); 1445 return true; 1446 case APValue::Float: 1447 Result = !Val.getFloat().isZero(); 1448 return true; 1449 case APValue::ComplexInt: 1450 Result = Val.getComplexIntReal().getBoolValue() || 1451 Val.getComplexIntImag().getBoolValue(); 1452 return true; 1453 case APValue::ComplexFloat: 1454 Result = !Val.getComplexFloatReal().isZero() || 1455 !Val.getComplexFloatImag().isZero(); 1456 return true; 1457 case APValue::LValue: 1458 return EvalPointerValueAsBool(Val, Result); 1459 case APValue::MemberPointer: 1460 Result = Val.getMemberPointerDecl(); 1461 return true; 1462 case APValue::Vector: 1463 case APValue::Array: 1464 case APValue::Struct: 1465 case APValue::Union: 1466 case APValue::AddrLabelDiff: 1467 return false; 1468 } 1469 1470 llvm_unreachable("unknown APValue kind"); 1471} 1472 1473static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result, 1474 EvalInfo &Info) { 1475 assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition"); 1476 APValue Val; 1477 if (!Evaluate(Val, Info, E)) 1478 return false; 1479 return HandleConversionToBool(Val, Result); 1480} 1481 1482template<typename T> 1483static void HandleOverflow(EvalInfo &Info, const Expr *E, 1484 const T &SrcValue, QualType DestType) { 1485 Info.CCEDiag(E, diag::note_constexpr_overflow) 1486 << SrcValue << DestType; 1487} 1488 1489static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E, 1490 QualType SrcType, const APFloat &Value, 1491 QualType DestType, APSInt &Result) { 1492 unsigned DestWidth = Info.Ctx.getIntWidth(DestType); 1493 // Determine whether we are converting to unsigned or signed. 1494 bool DestSigned = DestType->isSignedIntegerOrEnumerationType(); 1495 1496 Result = APSInt(DestWidth, !DestSigned); 1497 bool ignored; 1498 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored) 1499 & APFloat::opInvalidOp) 1500 HandleOverflow(Info, E, Value, DestType); 1501 return true; 1502} 1503 1504static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E, 1505 QualType SrcType, QualType DestType, 1506 APFloat &Result) { 1507 APFloat Value = Result; 1508 bool ignored; 1509 if (Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), 1510 APFloat::rmNearestTiesToEven, &ignored) 1511 & APFloat::opOverflow) 1512 HandleOverflow(Info, E, Value, DestType); 1513 return true; 1514} 1515 1516static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E, 1517 QualType DestType, QualType SrcType, 1518 APSInt &Value) { 1519 unsigned DestWidth = Info.Ctx.getIntWidth(DestType); 1520 APSInt Result = Value; 1521 // Figure out if this is a truncate, extend or noop cast. 1522 // If the input is signed, do a sign extend, noop, or truncate. 1523 Result = Result.extOrTrunc(DestWidth); 1524 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType()); 1525 return Result; 1526} 1527 1528static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E, 1529 QualType SrcType, const APSInt &Value, 1530 QualType DestType, APFloat &Result) { 1531 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1); 1532 if (Result.convertFromAPInt(Value, Value.isSigned(), 1533 APFloat::rmNearestTiesToEven) 1534 & APFloat::opOverflow) 1535 HandleOverflow(Info, E, Value, DestType); 1536 return true; 1537} 1538 1539static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E, 1540 APValue &Value, const FieldDecl *FD) { 1541 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield"); 1542 1543 if (!Value.isInt()) { 1544 // Trying to store a pointer-cast-to-integer into a bitfield. 1545 // FIXME: In this case, we should provide the diagnostic for casting 1546 // a pointer to an integer. 1547 assert(Value.isLValue() && "integral value neither int nor lvalue?"); 1548 Info.Diag(E); 1549 return false; 1550 } 1551 1552 APSInt &Int = Value.getInt(); 1553 unsigned OldBitWidth = Int.getBitWidth(); 1554 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx); 1555 if (NewBitWidth < OldBitWidth) 1556 Int = Int.trunc(NewBitWidth).extend(OldBitWidth); 1557 return true; 1558} 1559 1560static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E, 1561 llvm::APInt &Res) { 1562 APValue SVal; 1563 if (!Evaluate(SVal, Info, E)) 1564 return false; 1565 if (SVal.isInt()) { 1566 Res = SVal.getInt(); 1567 return true; 1568 } 1569 if (SVal.isFloat()) { 1570 Res = SVal.getFloat().bitcastToAPInt(); 1571 return true; 1572 } 1573 if (SVal.isVector()) { 1574 QualType VecTy = E->getType(); 1575 unsigned VecSize = Info.Ctx.getTypeSize(VecTy); 1576 QualType EltTy = VecTy->castAs<VectorType>()->getElementType(); 1577 unsigned EltSize = Info.Ctx.getTypeSize(EltTy); 1578 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); 1579 Res = llvm::APInt::getNullValue(VecSize); 1580 for (unsigned i = 0; i < SVal.getVectorLength(); i++) { 1581 APValue &Elt = SVal.getVectorElt(i); 1582 llvm::APInt EltAsInt; 1583 if (Elt.isInt()) { 1584 EltAsInt = Elt.getInt(); 1585 } else if (Elt.isFloat()) { 1586 EltAsInt = Elt.getFloat().bitcastToAPInt(); 1587 } else { 1588 // Don't try to handle vectors of anything other than int or float 1589 // (not sure if it's possible to hit this case). 1590 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1591 return false; 1592 } 1593 unsigned BaseEltSize = EltAsInt.getBitWidth(); 1594 if (BigEndian) 1595 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize); 1596 else 1597 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize); 1598 } 1599 return true; 1600 } 1601 // Give up if the input isn't an int, float, or vector. For example, we 1602 // reject "(v4i16)(intptr_t)&a". 1603 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1604 return false; 1605} 1606 1607/// Perform the given integer operation, which is known to need at most BitWidth 1608/// bits, and check for overflow in the original type (if that type was not an 1609/// unsigned type). 1610template<typename Operation> 1611static APSInt CheckedIntArithmetic(EvalInfo &Info, const Expr *E, 1612 const APSInt &LHS, const APSInt &RHS, 1613 unsigned BitWidth, Operation Op) { 1614 if (LHS.isUnsigned()) 1615 return Op(LHS, RHS); 1616 1617 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false); 1618 APSInt Result = Value.trunc(LHS.getBitWidth()); 1619 if (Result.extend(BitWidth) != Value) { 1620 if (Info.checkingForOverflow()) 1621 Info.Ctx.getDiagnostics().Report(E->getExprLoc(), 1622 diag::warn_integer_constant_overflow) 1623 << Result.toString(10) << E->getType(); 1624 else 1625 HandleOverflow(Info, E, Value, E->getType()); 1626 } 1627 return Result; 1628} 1629 1630/// Perform the given binary integer operation. 1631static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS, 1632 BinaryOperatorKind Opcode, APSInt RHS, 1633 APSInt &Result) { 1634 switch (Opcode) { 1635 default: 1636 Info.Diag(E); 1637 return false; 1638 case BO_Mul: 1639 Result = CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2, 1640 std::multiplies<APSInt>()); 1641 return true; 1642 case BO_Add: 1643 Result = CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, 1644 std::plus<APSInt>()); 1645 return true; 1646 case BO_Sub: 1647 Result = CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, 1648 std::minus<APSInt>()); 1649 return true; 1650 case BO_And: Result = LHS & RHS; return true; 1651 case BO_Xor: Result = LHS ^ RHS; return true; 1652 case BO_Or: Result = LHS | RHS; return true; 1653 case BO_Div: 1654 case BO_Rem: 1655 if (RHS == 0) { 1656 Info.Diag(E, diag::note_expr_divide_by_zero); 1657 return false; 1658 } 1659 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. 1660 if (RHS.isNegative() && RHS.isAllOnesValue() && 1661 LHS.isSigned() && LHS.isMinSignedValue()) 1662 HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType()); 1663 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS); 1664 return true; 1665 case BO_Shl: { 1666 if (Info.getLangOpts().OpenCL) 1667 // OpenCL 6.3j: shift values are effectively % word size of LHS. 1668 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), 1669 static_cast<uint64_t>(LHS.getBitWidth() - 1)), 1670 RHS.isUnsigned()); 1671 else if (RHS.isSigned() && RHS.isNegative()) { 1672 // During constant-folding, a negative shift is an opposite shift. Such 1673 // a shift is not a constant expression. 1674 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; 1675 RHS = -RHS; 1676 goto shift_right; 1677 } 1678 shift_left: 1679 // C++11 [expr.shift]p1: Shift width must be less than the bit width of 1680 // the shifted type. 1681 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); 1682 if (SA != RHS) { 1683 Info.CCEDiag(E, diag::note_constexpr_large_shift) 1684 << RHS << E->getType() << LHS.getBitWidth(); 1685 } else if (LHS.isSigned()) { 1686 // C++11 [expr.shift]p2: A signed left shift must have a non-negative 1687 // operand, and must not overflow the corresponding unsigned type. 1688 if (LHS.isNegative()) 1689 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS; 1690 else if (LHS.countLeadingZeros() < SA) 1691 Info.CCEDiag(E, diag::note_constexpr_lshift_discards); 1692 } 1693 Result = LHS << SA; 1694 return true; 1695 } 1696 case BO_Shr: { 1697 if (Info.getLangOpts().OpenCL) 1698 // OpenCL 6.3j: shift values are effectively % word size of LHS. 1699 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), 1700 static_cast<uint64_t>(LHS.getBitWidth() - 1)), 1701 RHS.isUnsigned()); 1702 else if (RHS.isSigned() && RHS.isNegative()) { 1703 // During constant-folding, a negative shift is an opposite shift. Such a 1704 // shift is not a constant expression. 1705 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; 1706 RHS = -RHS; 1707 goto shift_left; 1708 } 1709 shift_right: 1710 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the 1711 // shifted type. 1712 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); 1713 if (SA != RHS) 1714 Info.CCEDiag(E, diag::note_constexpr_large_shift) 1715 << RHS << E->getType() << LHS.getBitWidth(); 1716 Result = LHS >> SA; 1717 return true; 1718 } 1719 1720 case BO_LT: Result = LHS < RHS; return true; 1721 case BO_GT: Result = LHS > RHS; return true; 1722 case BO_LE: Result = LHS <= RHS; return true; 1723 case BO_GE: Result = LHS >= RHS; return true; 1724 case BO_EQ: Result = LHS == RHS; return true; 1725 case BO_NE: Result = LHS != RHS; return true; 1726 } 1727} 1728 1729/// Perform the given binary floating-point operation, in-place, on LHS. 1730static bool handleFloatFloatBinOp(EvalInfo &Info, const Expr *E, 1731 APFloat &LHS, BinaryOperatorKind Opcode, 1732 const APFloat &RHS) { 1733 switch (Opcode) { 1734 default: 1735 Info.Diag(E); 1736 return false; 1737 case BO_Mul: 1738 LHS.multiply(RHS, APFloat::rmNearestTiesToEven); 1739 break; 1740 case BO_Add: 1741 LHS.add(RHS, APFloat::rmNearestTiesToEven); 1742 break; 1743 case BO_Sub: 1744 LHS.subtract(RHS, APFloat::rmNearestTiesToEven); 1745 break; 1746 case BO_Div: 1747 LHS.divide(RHS, APFloat::rmNearestTiesToEven); 1748 break; 1749 } 1750 1751 if (LHS.isInfinity() || LHS.isNaN()) 1752 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN(); 1753 return true; 1754} 1755 1756/// Cast an lvalue referring to a base subobject to a derived class, by 1757/// truncating the lvalue's path to the given length. 1758static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result, 1759 const RecordDecl *TruncatedType, 1760 unsigned TruncatedElements) { 1761 SubobjectDesignator &D = Result.Designator; 1762 1763 // Check we actually point to a derived class object. 1764 if (TruncatedElements == D.Entries.size()) 1765 return true; 1766 assert(TruncatedElements >= D.MostDerivedPathLength && 1767 "not casting to a derived class"); 1768 if (!Result.checkSubobject(Info, E, CSK_Derived)) 1769 return false; 1770 1771 // Truncate the path to the subobject, and remove any derived-to-base offsets. 1772 const RecordDecl *RD = TruncatedType; 1773 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) { 1774 if (RD->isInvalidDecl()) return false; 1775 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 1776 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]); 1777 if (isVirtualBaseClass(D.Entries[I])) 1778 Result.Offset -= Layout.getVBaseClassOffset(Base); 1779 else 1780 Result.Offset -= Layout.getBaseClassOffset(Base); 1781 RD = Base; 1782 } 1783 D.Entries.resize(TruncatedElements); 1784 return true; 1785} 1786 1787static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj, 1788 const CXXRecordDecl *Derived, 1789 const CXXRecordDecl *Base, 1790 const ASTRecordLayout *RL = nullptr) { 1791 if (!RL) { 1792 if (Derived->isInvalidDecl()) return false; 1793 RL = &Info.Ctx.getASTRecordLayout(Derived); 1794 } 1795 1796 Obj.getLValueOffset() += RL->getBaseClassOffset(Base); 1797 Obj.addDecl(Info, E, Base, /*Virtual*/ false); 1798 return true; 1799} 1800 1801static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj, 1802 const CXXRecordDecl *DerivedDecl, 1803 const CXXBaseSpecifier *Base) { 1804 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl(); 1805 1806 if (!Base->isVirtual()) 1807 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl); 1808 1809 SubobjectDesignator &D = Obj.Designator; 1810 if (D.Invalid) 1811 return false; 1812 1813 // Extract most-derived object and corresponding type. 1814 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl(); 1815 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength)) 1816 return false; 1817 1818 // Find the virtual base class. 1819 if (DerivedDecl->isInvalidDecl()) return false; 1820 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl); 1821 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl); 1822 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true); 1823 return true; 1824} 1825 1826static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E, 1827 QualType Type, LValue &Result) { 1828 for (CastExpr::path_const_iterator PathI = E->path_begin(), 1829 PathE = E->path_end(); 1830 PathI != PathE; ++PathI) { 1831 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(), 1832 *PathI)) 1833 return false; 1834 Type = (*PathI)->getType(); 1835 } 1836 return true; 1837} 1838 1839/// Update LVal to refer to the given field, which must be a member of the type 1840/// currently described by LVal. 1841static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal, 1842 const FieldDecl *FD, 1843 const ASTRecordLayout *RL = nullptr) { 1844 if (!RL) { 1845 if (FD->getParent()->isInvalidDecl()) return false; 1846 RL = &Info.Ctx.getASTRecordLayout(FD->getParent()); 1847 } 1848 1849 unsigned I = FD->getFieldIndex(); 1850 LVal.Offset += Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)); 1851 LVal.addDecl(Info, E, FD); 1852 return true; 1853} 1854 1855/// Update LVal to refer to the given indirect field. 1856static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E, 1857 LValue &LVal, 1858 const IndirectFieldDecl *IFD) { 1859 for (const auto *C : IFD->chain()) 1860 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C))) 1861 return false; 1862 return true; 1863} 1864 1865/// Get the size of the given type in char units. 1866static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc, 1867 QualType Type, CharUnits &Size) { 1868 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc 1869 // extension. 1870 if (Type->isVoidType() || Type->isFunctionType()) { 1871 Size = CharUnits::One(); 1872 return true; 1873 } 1874 1875 if (!Type->isConstantSizeType()) { 1876 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2. 1877 // FIXME: Better diagnostic. 1878 Info.Diag(Loc); 1879 return false; 1880 } 1881 1882 Size = Info.Ctx.getTypeSizeInChars(Type); 1883 return true; 1884} 1885 1886/// Update a pointer value to model pointer arithmetic. 1887/// \param Info - Information about the ongoing evaluation. 1888/// \param E - The expression being evaluated, for diagnostic purposes. 1889/// \param LVal - The pointer value to be updated. 1890/// \param EltTy - The pointee type represented by LVal. 1891/// \param Adjustment - The adjustment, in objects of type EltTy, to add. 1892static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, 1893 LValue &LVal, QualType EltTy, 1894 int64_t Adjustment) { 1895 CharUnits SizeOfPointee; 1896 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee)) 1897 return false; 1898 1899 // Compute the new offset in the appropriate width. 1900 LVal.Offset += Adjustment * SizeOfPointee; 1901 LVal.adjustIndex(Info, E, Adjustment); 1902 return true; 1903} 1904 1905/// Update an lvalue to refer to a component of a complex number. 1906/// \param Info - Information about the ongoing evaluation. 1907/// \param LVal - The lvalue to be updated. 1908/// \param EltTy - The complex number's component type. 1909/// \param Imag - False for the real component, true for the imaginary. 1910static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E, 1911 LValue &LVal, QualType EltTy, 1912 bool Imag) { 1913 if (Imag) { 1914 CharUnits SizeOfComponent; 1915 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent)) 1916 return false; 1917 LVal.Offset += SizeOfComponent; 1918 } 1919 LVal.addComplex(Info, E, EltTy, Imag); 1920 return true; 1921} 1922 1923/// Try to evaluate the initializer for a variable declaration. 1924/// 1925/// \param Info Information about the ongoing evaluation. 1926/// \param E An expression to be used when printing diagnostics. 1927/// \param VD The variable whose initializer should be obtained. 1928/// \param Frame The frame in which the variable was created. Must be null 1929/// if this variable is not local to the evaluation. 1930/// \param Result Filled in with a pointer to the value of the variable. 1931static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E, 1932 const VarDecl *VD, CallStackFrame *Frame, 1933 APValue *&Result) { 1934 // If this is a parameter to an active constexpr function call, perform 1935 // argument substitution. 1936 if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) { 1937 // Assume arguments of a potential constant expression are unknown 1938 // constant expressions. 1939 if (Info.checkingPotentialConstantExpression()) 1940 return false; 1941 if (!Frame || !Frame->Arguments) { 1942 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1943 return false; 1944 } 1945 Result = &Frame->Arguments[PVD->getFunctionScopeIndex()]; 1946 return true; 1947 } 1948 1949 // If this is a local variable, dig out its value. 1950 if (Frame) { 1951 Result = Frame->getTemporary(VD); 1952 assert(Result && "missing value for local variable"); 1953 return true; 1954 } 1955 1956 // Dig out the initializer, and use the declaration which it's attached to. 1957 const Expr *Init = VD->getAnyInitializer(VD); 1958 if (!Init || Init->isValueDependent()) { 1959 // If we're checking a potential constant expression, the variable could be 1960 // initialized later. 1961 if (!Info.checkingPotentialConstantExpression()) 1962 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1963 return false; 1964 } 1965 1966 // If we're currently evaluating the initializer of this declaration, use that 1967 // in-flight value. 1968 if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) { 1969 Result = Info.EvaluatingDeclValue; 1970 return true; 1971 } 1972 1973 // Never evaluate the initializer of a weak variable. We can't be sure that 1974 // this is the definition which will be used. 1975 if (VD->isWeak()) { 1976 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1977 return false; 1978 } 1979 1980 // Check that we can fold the initializer. In C++, we will have already done 1981 // this in the cases where it matters for conformance. 1982 SmallVector<PartialDiagnosticAt, 8> Notes; 1983 if (!VD->evaluateValue(Notes)) { 1984 Info.Diag(E, diag::note_constexpr_var_init_non_constant, 1985 Notes.size() + 1) << VD; 1986 Info.Note(VD->getLocation(), diag::note_declared_at); 1987 Info.addNotes(Notes); 1988 return false; 1989 } else if (!VD->checkInitIsICE()) { 1990 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1991 Notes.size() + 1) << VD; 1992 Info.Note(VD->getLocation(), diag::note_declared_at); 1993 Info.addNotes(Notes); 1994 } 1995 1996 Result = VD->getEvaluatedValue(); 1997 return true; 1998} 1999 2000static bool IsConstNonVolatile(QualType T) { 2001 Qualifiers Quals = T.getQualifiers(); 2002 return Quals.hasConst() && !Quals.hasVolatile(); 2003} 2004 2005/// Get the base index of the given base class within an APValue representing 2006/// the given derived class. 2007static unsigned getBaseIndex(const CXXRecordDecl *Derived, 2008 const CXXRecordDecl *Base) { 2009 Base = Base->getCanonicalDecl(); 2010 unsigned Index = 0; 2011 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(), 2012 E = Derived->bases_end(); I != E; ++I, ++Index) { 2013 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base) 2014 return Index; 2015 } 2016 2017 llvm_unreachable("base class missing from derived class's bases list"); 2018} 2019 2020/// Extract the value of a character from a string literal. 2021static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit, 2022 uint64_t Index) { 2023 // FIXME: Support PredefinedExpr, ObjCEncodeExpr, MakeStringConstant 2024 const StringLiteral *S = cast<StringLiteral>(Lit); 2025 const ConstantArrayType *CAT = 2026 Info.Ctx.getAsConstantArrayType(S->getType()); 2027 assert(CAT && "string literal isn't an array"); 2028 QualType CharType = CAT->getElementType(); 2029 assert(CharType->isIntegerType() && "unexpected character type"); 2030 2031 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), 2032 CharType->isUnsignedIntegerType()); 2033 if (Index < S->getLength()) 2034 Value = S->getCodeUnit(Index); 2035 return Value; 2036} 2037 2038// Expand a string literal into an array of characters. 2039static void expandStringLiteral(EvalInfo &Info, const Expr *Lit, 2040 APValue &Result) { 2041 const StringLiteral *S = cast<StringLiteral>(Lit); 2042 const ConstantArrayType *CAT = 2043 Info.Ctx.getAsConstantArrayType(S->getType()); 2044 assert(CAT && "string literal isn't an array"); 2045 QualType CharType = CAT->getElementType(); 2046 assert(CharType->isIntegerType() && "unexpected character type"); 2047 2048 unsigned Elts = CAT->getSize().getZExtValue(); 2049 Result = APValue(APValue::UninitArray(), 2050 std::min(S->getLength(), Elts), Elts); 2051 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), 2052 CharType->isUnsignedIntegerType()); 2053 if (Result.hasArrayFiller()) 2054 Result.getArrayFiller() = APValue(Value); 2055 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) { 2056 Value = S->getCodeUnit(I); 2057 Result.getArrayInitializedElt(I) = APValue(Value); 2058 } 2059} 2060 2061// Expand an array so that it has more than Index filled elements. 2062static void expandArray(APValue &Array, unsigned Index) { 2063 unsigned Size = Array.getArraySize(); 2064 assert(Index < Size); 2065 2066 // Always at least double the number of elements for which we store a value. 2067 unsigned OldElts = Array.getArrayInitializedElts(); 2068 unsigned NewElts = std::max(Index+1, OldElts * 2); 2069 NewElts = std::min(Size, std::max(NewElts, 8u)); 2070 2071 // Copy the data across. 2072 APValue NewValue(APValue::UninitArray(), NewElts, Size); 2073 for (unsigned I = 0; I != OldElts; ++I) 2074 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I)); 2075 for (unsigned I = OldElts; I != NewElts; ++I) 2076 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller(); 2077 if (NewValue.hasArrayFiller()) 2078 NewValue.getArrayFiller() = Array.getArrayFiller(); 2079 Array.swap(NewValue); 2080} 2081 2082/// Kinds of access we can perform on an object, for diagnostics. 2083enum AccessKinds { 2084 AK_Read, 2085 AK_Assign, 2086 AK_Increment, 2087 AK_Decrement 2088}; 2089 2090/// A handle to a complete object (an object that is not a subobject of 2091/// another object). 2092struct CompleteObject { 2093 /// The value of the complete object. 2094 APValue *Value; 2095 /// The type of the complete object. 2096 QualType Type; 2097 2098 CompleteObject() : Value(nullptr) {} 2099 CompleteObject(APValue *Value, QualType Type) 2100 : Value(Value), Type(Type) { 2101 assert(Value && "missing value for complete object"); 2102 } 2103 2104 LLVM_EXPLICIT operator bool() const { return Value; } 2105}; 2106 2107/// Find the designated sub-object of an rvalue. 2108template<typename SubobjectHandler> 2109typename SubobjectHandler::result_type 2110findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj, 2111 const SubobjectDesignator &Sub, SubobjectHandler &handler) { 2112 if (Sub.Invalid) 2113 // A diagnostic will have already been produced. 2114 return handler.failed(); 2115 if (Sub.isOnePastTheEnd()) { 2116 if (Info.getLangOpts().CPlusPlus11) 2117 Info.Diag(E, diag::note_constexpr_access_past_end) 2118 << handler.AccessKind; 2119 else 2120 Info.Diag(E); 2121 return handler.failed(); 2122 } 2123 2124 APValue *O = Obj.Value; 2125 QualType ObjType = Obj.Type; 2126 const FieldDecl *LastField = nullptr; 2127 2128 // Walk the designator's path to find the subobject. 2129 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) { 2130 if (O->isUninit()) { 2131 if (!Info.checkingPotentialConstantExpression()) 2132 Info.Diag(E, diag::note_constexpr_access_uninit) << handler.AccessKind; 2133 return handler.failed(); 2134 } 2135 2136 if (I == N) { 2137 if (!handler.found(*O, ObjType)) 2138 return false; 2139 2140 // If we modified a bit-field, truncate it to the right width. 2141 if (handler.AccessKind != AK_Read && 2142 LastField && LastField->isBitField() && 2143 !truncateBitfieldValue(Info, E, *O, LastField)) 2144 return false; 2145 2146 return true; 2147 } 2148 2149 LastField = nullptr; 2150 if (ObjType->isArrayType()) { 2151 // Next subobject is an array element. 2152 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType); 2153 assert(CAT && "vla in literal type?"); 2154 uint64_t Index = Sub.Entries[I].ArrayIndex; 2155 if (CAT->getSize().ule(Index)) { 2156 // Note, it should not be possible to form a pointer with a valid 2157 // designator which points more than one past the end of the array. 2158 if (Info.getLangOpts().CPlusPlus11) 2159 Info.Diag(E, diag::note_constexpr_access_past_end) 2160 << handler.AccessKind; 2161 else 2162 Info.Diag(E); 2163 return handler.failed(); 2164 } 2165 2166 ObjType = CAT->getElementType(); 2167 2168 // An array object is represented as either an Array APValue or as an 2169 // LValue which refers to a string literal. 2170 if (O->isLValue()) { 2171 assert(I == N - 1 && "extracting subobject of character?"); 2172 assert(!O->hasLValuePath() || O->getLValuePath().empty()); 2173 if (handler.AccessKind != AK_Read) 2174 expandStringLiteral(Info, O->getLValueBase().get<const Expr *>(), 2175 *O); 2176 else 2177 return handler.foundString(*O, ObjType, Index); 2178 } 2179 2180 if (O->getArrayInitializedElts() > Index) 2181 O = &O->getArrayInitializedElt(Index); 2182 else if (handler.AccessKind != AK_Read) { 2183 expandArray(*O, Index); 2184 O = &O->getArrayInitializedElt(Index); 2185 } else 2186 O = &O->getArrayFiller(); 2187 } else if (ObjType->isAnyComplexType()) { 2188 // Next subobject is a complex number. 2189 uint64_t Index = Sub.Entries[I].ArrayIndex; 2190 if (Index > 1) { 2191 if (Info.getLangOpts().CPlusPlus11) 2192 Info.Diag(E, diag::note_constexpr_access_past_end) 2193 << handler.AccessKind; 2194 else 2195 Info.Diag(E); 2196 return handler.failed(); 2197 } 2198 2199 bool WasConstQualified = ObjType.isConstQualified(); 2200 ObjType = ObjType->castAs<ComplexType>()->getElementType(); 2201 if (WasConstQualified) 2202 ObjType.addConst(); 2203 2204 assert(I == N - 1 && "extracting subobject of scalar?"); 2205 if (O->isComplexInt()) { 2206 return handler.found(Index ? O->getComplexIntImag() 2207 : O->getComplexIntReal(), ObjType); 2208 } else { 2209 assert(O->isComplexFloat()); 2210 return handler.found(Index ? O->getComplexFloatImag() 2211 : O->getComplexFloatReal(), ObjType); 2212 } 2213 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) { 2214 if (Field->isMutable() && handler.AccessKind == AK_Read) { 2215 Info.Diag(E, diag::note_constexpr_ltor_mutable, 1) 2216 << Field; 2217 Info.Note(Field->getLocation(), diag::note_declared_at); 2218 return handler.failed(); 2219 } 2220 2221 // Next subobject is a class, struct or union field. 2222 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl(); 2223 if (RD->isUnion()) { 2224 const FieldDecl *UnionField = O->getUnionField(); 2225 if (!UnionField || 2226 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) { 2227 Info.Diag(E, diag::note_constexpr_access_inactive_union_member) 2228 << handler.AccessKind << Field << !UnionField << UnionField; 2229 return handler.failed(); 2230 } 2231 O = &O->getUnionValue(); 2232 } else 2233 O = &O->getStructField(Field->getFieldIndex()); 2234 2235 bool WasConstQualified = ObjType.isConstQualified(); 2236 ObjType = Field->getType(); 2237 if (WasConstQualified && !Field->isMutable()) 2238 ObjType.addConst(); 2239 2240 if (ObjType.isVolatileQualified()) { 2241 if (Info.getLangOpts().CPlusPlus) { 2242 // FIXME: Include a description of the path to the volatile subobject. 2243 Info.Diag(E, diag::note_constexpr_access_volatile_obj, 1) 2244 << handler.AccessKind << 2 << Field; 2245 Info.Note(Field->getLocation(), diag::note_declared_at); 2246 } else { 2247 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 2248 } 2249 return handler.failed(); 2250 } 2251 2252 LastField = Field; 2253 } else { 2254 // Next subobject is a base class. 2255 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl(); 2256 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]); 2257 O = &O->getStructBase(getBaseIndex(Derived, Base)); 2258 2259 bool WasConstQualified = ObjType.isConstQualified(); 2260 ObjType = Info.Ctx.getRecordType(Base); 2261 if (WasConstQualified) 2262 ObjType.addConst(); 2263 } 2264 } 2265} 2266 2267namespace { 2268struct ExtractSubobjectHandler { 2269 EvalInfo &Info; 2270 APValue &Result; 2271 2272 static const AccessKinds AccessKind = AK_Read; 2273 2274 typedef bool result_type; 2275 bool failed() { return false; } 2276 bool found(APValue &Subobj, QualType SubobjType) { 2277 Result = Subobj; 2278 return true; 2279 } 2280 bool found(APSInt &Value, QualType SubobjType) { 2281 Result = APValue(Value); 2282 return true; 2283 } 2284 bool found(APFloat &Value, QualType SubobjType) { 2285 Result = APValue(Value); 2286 return true; 2287 } 2288 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { 2289 Result = APValue(extractStringLiteralCharacter( 2290 Info, Subobj.getLValueBase().get<const Expr *>(), Character)); 2291 return true; 2292 } 2293}; 2294} // end anonymous namespace 2295 2296const AccessKinds ExtractSubobjectHandler::AccessKind; 2297 2298/// Extract the designated sub-object of an rvalue. 2299static bool extractSubobject(EvalInfo &Info, const Expr *E, 2300 const CompleteObject &Obj, 2301 const SubobjectDesignator &Sub, 2302 APValue &Result) { 2303 ExtractSubobjectHandler Handler = { Info, Result }; 2304 return findSubobject(Info, E, Obj, Sub, Handler); 2305} 2306 2307namespace { 2308struct ModifySubobjectHandler { 2309 EvalInfo &Info; 2310 APValue &NewVal; 2311 const Expr *E; 2312 2313 typedef bool result_type; 2314 static const AccessKinds AccessKind = AK_Assign; 2315 2316 bool checkConst(QualType QT) { 2317 // Assigning to a const object has undefined behavior. 2318 if (QT.isConstQualified()) { 2319 Info.Diag(E, diag::note_constexpr_modify_const_type) << QT; 2320 return false; 2321 } 2322 return true; 2323 } 2324 2325 bool failed() { return false; } 2326 bool found(APValue &Subobj, QualType SubobjType) { 2327 if (!checkConst(SubobjType)) 2328 return false; 2329 // We've been given ownership of NewVal, so just swap it in. 2330 Subobj.swap(NewVal); 2331 return true; 2332 } 2333 bool found(APSInt &Value, QualType SubobjType) { 2334 if (!checkConst(SubobjType)) 2335 return false; 2336 if (!NewVal.isInt()) { 2337 // Maybe trying to write a cast pointer value into a complex? 2338 Info.Diag(E); 2339 return false; 2340 } 2341 Value = NewVal.getInt(); 2342 return true; 2343 } 2344 bool found(APFloat &Value, QualType SubobjType) { 2345 if (!checkConst(SubobjType)) 2346 return false; 2347 Value = NewVal.getFloat(); 2348 return true; 2349 } 2350 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { 2351 llvm_unreachable("shouldn't encounter string elements with ExpandArrays"); 2352 } 2353}; 2354} // end anonymous namespace 2355 2356const AccessKinds ModifySubobjectHandler::AccessKind; 2357 2358/// Update the designated sub-object of an rvalue to the given value. 2359static bool modifySubobject(EvalInfo &Info, const Expr *E, 2360 const CompleteObject &Obj, 2361 const SubobjectDesignator &Sub, 2362 APValue &NewVal) { 2363 ModifySubobjectHandler Handler = { Info, NewVal, E }; 2364 return findSubobject(Info, E, Obj, Sub, Handler); 2365} 2366 2367/// Find the position where two subobject designators diverge, or equivalently 2368/// the length of the common initial subsequence. 2369static unsigned FindDesignatorMismatch(QualType ObjType, 2370 const SubobjectDesignator &A, 2371 const SubobjectDesignator &B, 2372 bool &WasArrayIndex) { 2373 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size()); 2374 for (/**/; I != N; ++I) { 2375 if (!ObjType.isNull() && 2376 (ObjType->isArrayType() || ObjType->isAnyComplexType())) { 2377 // Next subobject is an array element. 2378 if (A.Entries[I].ArrayIndex != B.Entries[I].ArrayIndex) { 2379 WasArrayIndex = true; 2380 return I; 2381 } 2382 if (ObjType->isAnyComplexType()) 2383 ObjType = ObjType->castAs<ComplexType>()->getElementType(); 2384 else 2385 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType(); 2386 } else { 2387 if (A.Entries[I].BaseOrMember != B.Entries[I].BaseOrMember) { 2388 WasArrayIndex = false; 2389 return I; 2390 } 2391 if (const FieldDecl *FD = getAsField(A.Entries[I])) 2392 // Next subobject is a field. 2393 ObjType = FD->getType(); 2394 else 2395 // Next subobject is a base class. 2396 ObjType = QualType(); 2397 } 2398 } 2399 WasArrayIndex = false; 2400 return I; 2401} 2402 2403/// Determine whether the given subobject designators refer to elements of the 2404/// same array object. 2405static bool AreElementsOfSameArray(QualType ObjType, 2406 const SubobjectDesignator &A, 2407 const SubobjectDesignator &B) { 2408 if (A.Entries.size() != B.Entries.size()) 2409 return false; 2410 2411 bool IsArray = A.MostDerivedArraySize != 0; 2412 if (IsArray && A.MostDerivedPathLength != A.Entries.size()) 2413 // A is a subobject of the array element. 2414 return false; 2415 2416 // If A (and B) designates an array element, the last entry will be the array 2417 // index. That doesn't have to match. Otherwise, we're in the 'implicit array 2418 // of length 1' case, and the entire path must match. 2419 bool WasArrayIndex; 2420 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex); 2421 return CommonLength >= A.Entries.size() - IsArray; 2422} 2423 2424/// Find the complete object to which an LValue refers. 2425CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E, AccessKinds AK, 2426 const LValue &LVal, QualType LValType) { 2427 if (!LVal.Base) { 2428 Info.Diag(E, diag::note_constexpr_access_null) << AK; 2429 return CompleteObject(); 2430 } 2431 2432 CallStackFrame *Frame = nullptr; 2433 if (LVal.CallIndex) { 2434 Frame = Info.getCallFrame(LVal.CallIndex); 2435 if (!Frame) { 2436 Info.Diag(E, diag::note_constexpr_lifetime_ended, 1) 2437 << AK << LVal.Base.is<const ValueDecl*>(); 2438 NoteLValueLocation(Info, LVal.Base); 2439 return CompleteObject(); 2440 } 2441 } 2442 2443 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type 2444 // is not a constant expression (even if the object is non-volatile). We also 2445 // apply this rule to C++98, in order to conform to the expected 'volatile' 2446 // semantics. 2447 if (LValType.isVolatileQualified()) { 2448 if (Info.getLangOpts().CPlusPlus) 2449 Info.Diag(E, diag::note_constexpr_access_volatile_type) 2450 << AK << LValType; 2451 else 2452 Info.Diag(E); 2453 return CompleteObject(); 2454 } 2455 2456 // Compute value storage location and type of base object. 2457 APValue *BaseVal = nullptr; 2458 QualType BaseType = getType(LVal.Base); 2459 2460 if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl*>()) { 2461 // In C++98, const, non-volatile integers initialized with ICEs are ICEs. 2462 // In C++11, constexpr, non-volatile variables initialized with constant 2463 // expressions are constant expressions too. Inside constexpr functions, 2464 // parameters are constant expressions even if they're non-const. 2465 // In C++1y, objects local to a constant expression (those with a Frame) are 2466 // both readable and writable inside constant expressions. 2467 // In C, such things can also be folded, although they are not ICEs. 2468 const VarDecl *VD = dyn_cast<VarDecl>(D); 2469 if (VD) { 2470 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx)) 2471 VD = VDef; 2472 } 2473 if (!VD || VD->isInvalidDecl()) { 2474 Info.Diag(E); 2475 return CompleteObject(); 2476 } 2477 2478 // Accesses of volatile-qualified objects are not allowed. 2479 if (BaseType.isVolatileQualified()) { 2480 if (Info.getLangOpts().CPlusPlus) { 2481 Info.Diag(E, diag::note_constexpr_access_volatile_obj, 1) 2482 << AK << 1 << VD; 2483 Info.Note(VD->getLocation(), diag::note_declared_at); 2484 } else { 2485 Info.Diag(E); 2486 } 2487 return CompleteObject(); 2488 } 2489 2490 // Unless we're looking at a local variable or argument in a constexpr call, 2491 // the variable we're reading must be const. 2492 if (!Frame) { 2493 if (Info.getLangOpts().CPlusPlus1y && 2494 VD == Info.EvaluatingDecl.dyn_cast<const ValueDecl *>()) { 2495 // OK, we can read and modify an object if we're in the process of 2496 // evaluating its initializer, because its lifetime began in this 2497 // evaluation. 2498 } else if (AK != AK_Read) { 2499 // All the remaining cases only permit reading. 2500 Info.Diag(E, diag::note_constexpr_modify_global); 2501 return CompleteObject(); 2502 } else if (VD->isConstexpr()) { 2503 // OK, we can read this variable. 2504 } else if (BaseType->isIntegralOrEnumerationType()) { 2505 if (!BaseType.isConstQualified()) { 2506 if (Info.getLangOpts().CPlusPlus) { 2507 Info.Diag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD; 2508 Info.Note(VD->getLocation(), diag::note_declared_at); 2509 } else { 2510 Info.Diag(E); 2511 } 2512 return CompleteObject(); 2513 } 2514 } else if (BaseType->isFloatingType() && BaseType.isConstQualified()) { 2515 // We support folding of const floating-point types, in order to make 2516 // static const data members of such types (supported as an extension) 2517 // more useful. 2518 if (Info.getLangOpts().CPlusPlus11) { 2519 Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; 2520 Info.Note(VD->getLocation(), diag::note_declared_at); 2521 } else { 2522 Info.CCEDiag(E); 2523 } 2524 } else { 2525 // FIXME: Allow folding of values of any literal type in all languages. 2526 if (Info.getLangOpts().CPlusPlus11) { 2527 Info.Diag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; 2528 Info.Note(VD->getLocation(), diag::note_declared_at); 2529 } else { 2530 Info.Diag(E); 2531 } 2532 return CompleteObject(); 2533 } 2534 } 2535 2536 if (!evaluateVarDeclInit(Info, E, VD, Frame, BaseVal)) 2537 return CompleteObject(); 2538 } else { 2539 const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); 2540 2541 if (!Frame) { 2542 if (const MaterializeTemporaryExpr *MTE = 2543 dyn_cast<MaterializeTemporaryExpr>(Base)) { 2544 assert(MTE->getStorageDuration() == SD_Static && 2545 "should have a frame for a non-global materialized temporary"); 2546 2547 // Per C++1y [expr.const]p2: 2548 // an lvalue-to-rvalue conversion [is not allowed unless it applies to] 2549 // - a [...] glvalue of integral or enumeration type that refers to 2550 // a non-volatile const object [...] 2551 // [...] 2552 // - a [...] glvalue of literal type that refers to a non-volatile 2553 // object whose lifetime began within the evaluation of e. 2554 // 2555 // C++11 misses the 'began within the evaluation of e' check and 2556 // instead allows all temporaries, including things like: 2557 // int &&r = 1; 2558 // int x = ++r; 2559 // constexpr int k = r; 2560 // Therefore we use the C++1y rules in C++11 too. 2561 const ValueDecl *VD = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>(); 2562 const ValueDecl *ED = MTE->getExtendingDecl(); 2563 if (!(BaseType.isConstQualified() && 2564 BaseType->isIntegralOrEnumerationType()) && 2565 !(VD && VD->getCanonicalDecl() == ED->getCanonicalDecl())) { 2566 Info.Diag(E, diag::note_constexpr_access_static_temporary, 1) << AK; 2567 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here); 2568 return CompleteObject(); 2569 } 2570 2571 BaseVal = Info.Ctx.getMaterializedTemporaryValue(MTE, false); 2572 assert(BaseVal && "got reference to unevaluated temporary"); 2573 } else { 2574 Info.Diag(E); 2575 return CompleteObject(); 2576 } 2577 } else { 2578 BaseVal = Frame->getTemporary(Base); 2579 assert(BaseVal && "missing value for temporary"); 2580 } 2581 2582 // Volatile temporary objects cannot be accessed in constant expressions. 2583 if (BaseType.isVolatileQualified()) { 2584 if (Info.getLangOpts().CPlusPlus) { 2585 Info.Diag(E, diag::note_constexpr_access_volatile_obj, 1) 2586 << AK << 0; 2587 Info.Note(Base->getExprLoc(), diag::note_constexpr_temporary_here); 2588 } else { 2589 Info.Diag(E); 2590 } 2591 return CompleteObject(); 2592 } 2593 } 2594 2595 // During the construction of an object, it is not yet 'const'. 2596 // FIXME: We don't set up EvaluatingDecl for local variables or temporaries, 2597 // and this doesn't do quite the right thing for const subobjects of the 2598 // object under construction. 2599 if (LVal.getLValueBase() == Info.EvaluatingDecl) { 2600 BaseType = Info.Ctx.getCanonicalType(BaseType); 2601 BaseType.removeLocalConst(); 2602 } 2603 2604 // In C++1y, we can't safely access any mutable state when we might be 2605 // evaluating after an unmodeled side effect or an evaluation failure. 2606 // 2607 // FIXME: Not all local state is mutable. Allow local constant subobjects 2608 // to be read here (but take care with 'mutable' fields). 2609 if (Frame && Info.getLangOpts().CPlusPlus1y && 2610 (Info.EvalStatus.HasSideEffects || Info.keepEvaluatingAfterFailure())) 2611 return CompleteObject(); 2612 2613 return CompleteObject(BaseVal, BaseType); 2614} 2615 2616/// \brief Perform an lvalue-to-rvalue conversion on the given glvalue. This 2617/// can also be used for 'lvalue-to-lvalue' conversions for looking up the 2618/// glvalue referred to by an entity of reference type. 2619/// 2620/// \param Info - Information about the ongoing evaluation. 2621/// \param Conv - The expression for which we are performing the conversion. 2622/// Used for diagnostics. 2623/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the 2624/// case of a non-class type). 2625/// \param LVal - The glvalue on which we are attempting to perform this action. 2626/// \param RVal - The produced value will be placed here. 2627static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, 2628 QualType Type, 2629 const LValue &LVal, APValue &RVal) { 2630 if (LVal.Designator.Invalid) 2631 return false; 2632 2633 // Check for special cases where there is no existing APValue to look at. 2634 const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); 2635 if (!LVal.Designator.Invalid && Base && !LVal.CallIndex && 2636 !Type.isVolatileQualified()) { 2637 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) { 2638 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the 2639 // initializer until now for such expressions. Such an expression can't be 2640 // an ICE in C, so this only matters for fold. 2641 assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?"); 2642 if (Type.isVolatileQualified()) { 2643 Info.Diag(Conv); 2644 return false; 2645 } 2646 APValue Lit; 2647 if (!Evaluate(Lit, Info, CLE->getInitializer())) 2648 return false; 2649 CompleteObject LitObj(&Lit, Base->getType()); 2650 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal); 2651 } else if (isa<StringLiteral>(Base)) { 2652 // We represent a string literal array as an lvalue pointing at the 2653 // corresponding expression, rather than building an array of chars. 2654 // FIXME: Support PredefinedExpr, ObjCEncodeExpr, MakeStringConstant 2655 APValue Str(Base, CharUnits::Zero(), APValue::NoLValuePath(), 0); 2656 CompleteObject StrObj(&Str, Base->getType()); 2657 return extractSubobject(Info, Conv, StrObj, LVal.Designator, RVal); 2658 } 2659 } 2660 2661 CompleteObject Obj = findCompleteObject(Info, Conv, AK_Read, LVal, Type); 2662 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal); 2663} 2664 2665/// Perform an assignment of Val to LVal. Takes ownership of Val. 2666static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal, 2667 QualType LValType, APValue &Val) { 2668 if (LVal.Designator.Invalid) 2669 return false; 2670 2671 if (!Info.getLangOpts().CPlusPlus1y) { 2672 Info.Diag(E); 2673 return false; 2674 } 2675 2676 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); 2677 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val); 2678} 2679 2680static bool isOverflowingIntegerType(ASTContext &Ctx, QualType T) { 2681 return T->isSignedIntegerType() && 2682 Ctx.getIntWidth(T) >= Ctx.getIntWidth(Ctx.IntTy); 2683} 2684 2685namespace { 2686struct CompoundAssignSubobjectHandler { 2687 EvalInfo &Info; 2688 const Expr *E; 2689 QualType PromotedLHSType; 2690 BinaryOperatorKind Opcode; 2691 const APValue &RHS; 2692 2693 static const AccessKinds AccessKind = AK_Assign; 2694 2695 typedef bool result_type; 2696 2697 bool checkConst(QualType QT) { 2698 // Assigning to a const object has undefined behavior. 2699 if (QT.isConstQualified()) { 2700 Info.Diag(E, diag::note_constexpr_modify_const_type) << QT; 2701 return false; 2702 } 2703 return true; 2704 } 2705 2706 bool failed() { return false; } 2707 bool found(APValue &Subobj, QualType SubobjType) { 2708 switch (Subobj.getKind()) { 2709 case APValue::Int: 2710 return found(Subobj.getInt(), SubobjType); 2711 case APValue::Float: 2712 return found(Subobj.getFloat(), SubobjType); 2713 case APValue::ComplexInt: 2714 case APValue::ComplexFloat: 2715 // FIXME: Implement complex compound assignment. 2716 Info.Diag(E); 2717 return false; 2718 case APValue::LValue: 2719 return foundPointer(Subobj, SubobjType); 2720 default: 2721 // FIXME: can this happen? 2722 Info.Diag(E); 2723 return false; 2724 } 2725 } 2726 bool found(APSInt &Value, QualType SubobjType) { 2727 if (!checkConst(SubobjType)) 2728 return false; 2729 2730 if (!SubobjType->isIntegerType() || !RHS.isInt()) { 2731 // We don't support compound assignment on integer-cast-to-pointer 2732 // values. 2733 Info.Diag(E); 2734 return false; 2735 } 2736 2737 APSInt LHS = HandleIntToIntCast(Info, E, PromotedLHSType, 2738 SubobjType, Value); 2739 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS)) 2740 return false; 2741 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS); 2742 return true; 2743 } 2744 bool found(APFloat &Value, QualType SubobjType) { 2745 return checkConst(SubobjType) && 2746 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType, 2747 Value) && 2748 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) && 2749 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value); 2750 } 2751 bool foundPointer(APValue &Subobj, QualType SubobjType) { 2752 if (!checkConst(SubobjType)) 2753 return false; 2754 2755 QualType PointeeType; 2756 if (const PointerType *PT = SubobjType->getAs<PointerType>()) 2757 PointeeType = PT->getPointeeType(); 2758 2759 if (PointeeType.isNull() || !RHS.isInt() || 2760 (Opcode != BO_Add && Opcode != BO_Sub)) { 2761 Info.Diag(E); 2762 return false; 2763 } 2764 2765 int64_t Offset = getExtValue(RHS.getInt()); 2766 if (Opcode == BO_Sub) 2767 Offset = -Offset; 2768 2769 LValue LVal; 2770 LVal.setFrom(Info.Ctx, Subobj); 2771 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset)) 2772 return false; 2773 LVal.moveInto(Subobj); 2774 return true; 2775 } 2776 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { 2777 llvm_unreachable("shouldn't encounter string elements here"); 2778 } 2779}; 2780} // end anonymous namespace 2781 2782const AccessKinds CompoundAssignSubobjectHandler::AccessKind; 2783 2784/// Perform a compound assignment of LVal <op>= RVal. 2785static bool handleCompoundAssignment( 2786 EvalInfo &Info, const Expr *E, 2787 const LValue &LVal, QualType LValType, QualType PromotedLValType, 2788 BinaryOperatorKind Opcode, const APValue &RVal) { 2789 if (LVal.Designator.Invalid) 2790 return false; 2791 2792 if (!Info.getLangOpts().CPlusPlus1y) { 2793 Info.Diag(E); 2794 return false; 2795 } 2796 2797 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); 2798 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode, 2799 RVal }; 2800 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); 2801} 2802 2803namespace { 2804struct IncDecSubobjectHandler { 2805 EvalInfo &Info; 2806 const Expr *E; 2807 AccessKinds AccessKind; 2808 APValue *Old; 2809 2810 typedef bool result_type; 2811 2812 bool checkConst(QualType QT) { 2813 // Assigning to a const object has undefined behavior. 2814 if (QT.isConstQualified()) { 2815 Info.Diag(E, diag::note_constexpr_modify_const_type) << QT; 2816 return false; 2817 } 2818 return true; 2819 } 2820 2821 bool failed() { return false; } 2822 bool found(APValue &Subobj, QualType SubobjType) { 2823 // Stash the old value. Also clear Old, so we don't clobber it later 2824 // if we're post-incrementing a complex. 2825 if (Old) { 2826 *Old = Subobj; 2827 Old = nullptr; 2828 } 2829 2830 switch (Subobj.getKind()) { 2831 case APValue::Int: 2832 return found(Subobj.getInt(), SubobjType); 2833 case APValue::Float: 2834 return found(Subobj.getFloat(), SubobjType); 2835 case APValue::ComplexInt: 2836 return found(Subobj.getComplexIntReal(), 2837 SubobjType->castAs<ComplexType>()->getElementType() 2838 .withCVRQualifiers(SubobjType.getCVRQualifiers())); 2839 case APValue::ComplexFloat: 2840 return found(Subobj.getComplexFloatReal(), 2841 SubobjType->castAs<ComplexType>()->getElementType() 2842 .withCVRQualifiers(SubobjType.getCVRQualifiers())); 2843 case APValue::LValue: 2844 return foundPointer(Subobj, SubobjType); 2845 default: 2846 // FIXME: can this happen? 2847 Info.Diag(E); 2848 return false; 2849 } 2850 } 2851 bool found(APSInt &Value, QualType SubobjType) { 2852 if (!checkConst(SubobjType)) 2853 return false; 2854 2855 if (!SubobjType->isIntegerType()) { 2856 // We don't support increment / decrement on integer-cast-to-pointer 2857 // values. 2858 Info.Diag(E); 2859 return false; 2860 } 2861 2862 if (Old) *Old = APValue(Value); 2863 2864 // bool arithmetic promotes to int, and the conversion back to bool 2865 // doesn't reduce mod 2^n, so special-case it. 2866 if (SubobjType->isBooleanType()) { 2867 if (AccessKind == AK_Increment) 2868 Value = 1; 2869 else 2870 Value = !Value; 2871 return true; 2872 } 2873 2874 bool WasNegative = Value.isNegative(); 2875 if (AccessKind == AK_Increment) { 2876 ++Value; 2877 2878 if (!WasNegative && Value.isNegative() && 2879 isOverflowingIntegerType(Info.Ctx, SubobjType)) { 2880 APSInt ActualValue(Value, /*IsUnsigned*/true); 2881 HandleOverflow(Info, E, ActualValue, SubobjType); 2882 } 2883 } else { 2884 --Value; 2885 2886 if (WasNegative && !Value.isNegative() && 2887 isOverflowingIntegerType(Info.Ctx, SubobjType)) { 2888 unsigned BitWidth = Value.getBitWidth(); 2889 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false); 2890 ActualValue.setBit(BitWidth); 2891 HandleOverflow(Info, E, ActualValue, SubobjType); 2892 } 2893 } 2894 return true; 2895 } 2896 bool found(APFloat &Value, QualType SubobjType) { 2897 if (!checkConst(SubobjType)) 2898 return false; 2899 2900 if (Old) *Old = APValue(Value); 2901 2902 APFloat One(Value.getSemantics(), 1); 2903 if (AccessKind == AK_Increment) 2904 Value.add(One, APFloat::rmNearestTiesToEven); 2905 else 2906 Value.subtract(One, APFloat::rmNearestTiesToEven); 2907 return true; 2908 } 2909 bool foundPointer(APValue &Subobj, QualType SubobjType) { 2910 if (!checkConst(SubobjType)) 2911 return false; 2912 2913 QualType PointeeType; 2914 if (const PointerType *PT = SubobjType->getAs<PointerType>()) 2915 PointeeType = PT->getPointeeType(); 2916 else { 2917 Info.Diag(E); 2918 return false; 2919 } 2920 2921 LValue LVal; 2922 LVal.setFrom(Info.Ctx, Subobj); 2923 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, 2924 AccessKind == AK_Increment ? 1 : -1)) 2925 return false; 2926 LVal.moveInto(Subobj); 2927 return true; 2928 } 2929 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { 2930 llvm_unreachable("shouldn't encounter string elements here"); 2931 } 2932}; 2933} // end anonymous namespace 2934 2935/// Perform an increment or decrement on LVal. 2936static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal, 2937 QualType LValType, bool IsIncrement, APValue *Old) { 2938 if (LVal.Designator.Invalid) 2939 return false; 2940 2941 if (!Info.getLangOpts().CPlusPlus1y) { 2942 Info.Diag(E); 2943 return false; 2944 } 2945 2946 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement; 2947 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType); 2948 IncDecSubobjectHandler Handler = { Info, E, AK, Old }; 2949 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); 2950} 2951 2952/// Build an lvalue for the object argument of a member function call. 2953static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object, 2954 LValue &This) { 2955 if (Object->getType()->isPointerType()) 2956 return EvaluatePointer(Object, This, Info); 2957 2958 if (Object->isGLValue()) 2959 return EvaluateLValue(Object, This, Info); 2960 2961 if (Object->getType()->isLiteralType(Info.Ctx)) 2962 return EvaluateTemporary(Object, This, Info); 2963 2964 Info.Diag(Object, diag::note_constexpr_nonliteral) << Object->getType(); 2965 return false; 2966} 2967 2968/// HandleMemberPointerAccess - Evaluate a member access operation and build an 2969/// lvalue referring to the result. 2970/// 2971/// \param Info - Information about the ongoing evaluation. 2972/// \param LV - An lvalue referring to the base of the member pointer. 2973/// \param RHS - The member pointer expression. 2974/// \param IncludeMember - Specifies whether the member itself is included in 2975/// the resulting LValue subobject designator. This is not possible when 2976/// creating a bound member function. 2977/// \return The field or method declaration to which the member pointer refers, 2978/// or 0 if evaluation fails. 2979static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, 2980 QualType LVType, 2981 LValue &LV, 2982 const Expr *RHS, 2983 bool IncludeMember = true) { 2984 MemberPtr MemPtr; 2985 if (!EvaluateMemberPointer(RHS, MemPtr, Info)) 2986 return nullptr; 2987 2988 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to 2989 // member value, the behavior is undefined. 2990 if (!MemPtr.getDecl()) { 2991 // FIXME: Specific diagnostic. 2992 Info.Diag(RHS); 2993 return nullptr; 2994 } 2995 2996 if (MemPtr.isDerivedMember()) { 2997 // This is a member of some derived class. Truncate LV appropriately. 2998 // The end of the derived-to-base path for the base object must match the 2999 // derived-to-base path for the member pointer. 3000 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() > 3001 LV.Designator.Entries.size()) { 3002 Info.Diag(RHS); 3003 return nullptr; 3004 } 3005 unsigned PathLengthToMember = 3006 LV.Designator.Entries.size() - MemPtr.Path.size(); 3007 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) { 3008 const CXXRecordDecl *LVDecl = getAsBaseClass( 3009 LV.Designator.Entries[PathLengthToMember + I]); 3010 const CXXRecordDecl *MPDecl = MemPtr.Path[I]; 3011 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) { 3012 Info.Diag(RHS); 3013 return nullptr; 3014 } 3015 } 3016 3017 // Truncate the lvalue to the appropriate derived class. 3018 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(), 3019 PathLengthToMember)) 3020 return nullptr; 3021 } else if (!MemPtr.Path.empty()) { 3022 // Extend the LValue path with the member pointer's path. 3023 LV.Designator.Entries.reserve(LV.Designator.Entries.size() + 3024 MemPtr.Path.size() + IncludeMember); 3025 3026 // Walk down to the appropriate base class. 3027 if (const PointerType *PT = LVType->getAs<PointerType>()) 3028 LVType = PT->getPointeeType(); 3029 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl(); 3030 assert(RD && "member pointer access on non-class-type expression"); 3031 // The first class in the path is that of the lvalue. 3032 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) { 3033 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1]; 3034 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base)) 3035 return nullptr; 3036 RD = Base; 3037 } 3038 // Finally cast to the class containing the member. 3039 if (!HandleLValueDirectBase(Info, RHS, LV, RD, 3040 MemPtr.getContainingRecord())) 3041 return nullptr; 3042 } 3043 3044 // Add the member. Note that we cannot build bound member functions here. 3045 if (IncludeMember) { 3046 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) { 3047 if (!HandleLValueMember(Info, RHS, LV, FD)) 3048 return nullptr; 3049 } else if (const IndirectFieldDecl *IFD = 3050 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) { 3051 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD)) 3052 return nullptr; 3053 } else { 3054 llvm_unreachable("can't construct reference to bound member function"); 3055 } 3056 } 3057 3058 return MemPtr.getDecl(); 3059} 3060 3061static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, 3062 const BinaryOperator *BO, 3063 LValue &LV, 3064 bool IncludeMember = true) { 3065 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI); 3066 3067 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) { 3068 if (Info.keepEvaluatingAfterFailure()) { 3069 MemberPtr MemPtr; 3070 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info); 3071 } 3072 return nullptr; 3073 } 3074 3075 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV, 3076 BO->getRHS(), IncludeMember); 3077} 3078 3079/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on 3080/// the provided lvalue, which currently refers to the base object. 3081static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E, 3082 LValue &Result) { 3083 SubobjectDesignator &D = Result.Designator; 3084 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived)) 3085 return false; 3086 3087 QualType TargetQT = E->getType(); 3088 if (const PointerType *PT = TargetQT->getAs<PointerType>()) 3089 TargetQT = PT->getPointeeType(); 3090 3091 // Check this cast lands within the final derived-to-base subobject path. 3092 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) { 3093 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) 3094 << D.MostDerivedType << TargetQT; 3095 return false; 3096 } 3097 3098 // Check the type of the final cast. We don't need to check the path, 3099 // since a cast can only be formed if the path is unique. 3100 unsigned NewEntriesSize = D.Entries.size() - E->path_size(); 3101 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl(); 3102 const CXXRecordDecl *FinalType; 3103 if (NewEntriesSize == D.MostDerivedPathLength) 3104 FinalType = D.MostDerivedType->getAsCXXRecordDecl(); 3105 else 3106 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]); 3107 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) { 3108 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) 3109 << D.MostDerivedType << TargetQT; 3110 return false; 3111 } 3112 3113 // Truncate the lvalue to the appropriate derived class. 3114 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize); 3115} 3116 3117namespace { 3118enum EvalStmtResult { 3119 /// Evaluation failed. 3120 ESR_Failed, 3121 /// Hit a 'return' statement. 3122 ESR_Returned, 3123 /// Evaluation succeeded. 3124 ESR_Succeeded, 3125 /// Hit a 'continue' statement. 3126 ESR_Continue, 3127 /// Hit a 'break' statement. 3128 ESR_Break, 3129 /// Still scanning for 'case' or 'default' statement. 3130 ESR_CaseNotFound 3131}; 3132} 3133 3134static bool EvaluateDecl(EvalInfo &Info, const Decl *D) { 3135 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) { 3136 // We don't need to evaluate the initializer for a static local. 3137 if (!VD->hasLocalStorage()) 3138 return true; 3139 3140 LValue Result; 3141 Result.set(VD, Info.CurrentCall->Index); 3142 APValue &Val = Info.CurrentCall->createTemporary(VD, true); 3143 3144 const Expr *InitE = VD->getInit(); 3145 if (!InitE) { 3146 Info.Diag(D->getLocStart(), diag::note_constexpr_uninitialized) 3147 << false << VD->getType(); 3148 Val = APValue(); 3149 return false; 3150 } 3151 3152 if (InitE->isValueDependent()) 3153 return false; 3154 3155 if (!EvaluateInPlace(Val, Info, Result, InitE)) { 3156 // Wipe out any partially-computed value, to allow tracking that this 3157 // evaluation failed. 3158 Val = APValue(); 3159 return false; 3160 } 3161 } 3162 3163 return true; 3164} 3165 3166/// Evaluate a condition (either a variable declaration or an expression). 3167static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl, 3168 const Expr *Cond, bool &Result) { 3169 FullExpressionRAII Scope(Info); 3170 if (CondDecl && !EvaluateDecl(Info, CondDecl)) 3171 return false; 3172 return EvaluateAsBooleanCondition(Cond, Result, Info); 3173} 3174 3175static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info, 3176 const Stmt *S, 3177 const SwitchCase *SC = nullptr); 3178 3179/// Evaluate the body of a loop, and translate the result as appropriate. 3180static EvalStmtResult EvaluateLoopBody(APValue &Result, EvalInfo &Info, 3181 const Stmt *Body, 3182 const SwitchCase *Case = nullptr) { 3183 BlockScopeRAII Scope(Info); 3184 switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case)) { 3185 case ESR_Break: 3186 return ESR_Succeeded; 3187 case ESR_Succeeded: 3188 case ESR_Continue: 3189 return ESR_Continue; 3190 case ESR_Failed: 3191 case ESR_Returned: 3192 case ESR_CaseNotFound: 3193 return ESR; 3194 } 3195 llvm_unreachable("Invalid EvalStmtResult!"); 3196} 3197 3198/// Evaluate a switch statement. 3199static EvalStmtResult EvaluateSwitch(APValue &Result, EvalInfo &Info, 3200 const SwitchStmt *SS) { 3201 BlockScopeRAII Scope(Info); 3202 3203 // Evaluate the switch condition. 3204 APSInt Value; 3205 { 3206 FullExpressionRAII Scope(Info); 3207 if (SS->getConditionVariable() && 3208 !EvaluateDecl(Info, SS->getConditionVariable())) 3209 return ESR_Failed; 3210 if (!EvaluateInteger(SS->getCond(), Value, Info)) 3211 return ESR_Failed; 3212 } 3213 3214 // Find the switch case corresponding to the value of the condition. 3215 // FIXME: Cache this lookup. 3216 const SwitchCase *Found = nullptr; 3217 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC; 3218 SC = SC->getNextSwitchCase()) { 3219 if (isa<DefaultStmt>(SC)) { 3220 Found = SC; 3221 continue; 3222 } 3223 3224 const CaseStmt *CS = cast<CaseStmt>(SC); 3225 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx); 3226 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx) 3227 : LHS; 3228 if (LHS <= Value && Value <= RHS) { 3229 Found = SC; 3230 break; 3231 } 3232 } 3233 3234 if (!Found) 3235 return ESR_Succeeded; 3236 3237 // Search the switch body for the switch case and evaluate it from there. 3238 switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found)) { 3239 case ESR_Break: 3240 return ESR_Succeeded; 3241 case ESR_Succeeded: 3242 case ESR_Continue: 3243 case ESR_Failed: 3244 case ESR_Returned: 3245 return ESR; 3246 case ESR_CaseNotFound: 3247 // This can only happen if the switch case is nested within a statement 3248 // expression. We have no intention of supporting that. 3249 Info.Diag(Found->getLocStart(), diag::note_constexpr_stmt_expr_unsupported); 3250 return ESR_Failed; 3251 } 3252 llvm_unreachable("Invalid EvalStmtResult!"); 3253} 3254 3255// Evaluate a statement. 3256static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info, 3257 const Stmt *S, const SwitchCase *Case) { 3258 if (!Info.nextStep(S)) 3259 return ESR_Failed; 3260 3261 // If we're hunting down a 'case' or 'default' label, recurse through 3262 // substatements until we hit the label. 3263 if (Case) { 3264 // FIXME: We don't start the lifetime of objects whose initialization we 3265 // jump over. However, such objects must be of class type with a trivial 3266 // default constructor that initialize all subobjects, so must be empty, 3267 // so this almost never matters. 3268 switch (S->getStmtClass()) { 3269 case Stmt::CompoundStmtClass: 3270 // FIXME: Precompute which substatement of a compound statement we 3271 // would jump to, and go straight there rather than performing a 3272 // linear scan each time. 3273 case Stmt::LabelStmtClass: 3274 case Stmt::AttributedStmtClass: 3275 case Stmt::DoStmtClass: 3276 break; 3277 3278 case Stmt::CaseStmtClass: 3279 case Stmt::DefaultStmtClass: 3280 if (Case == S) 3281 Case = nullptr; 3282 break; 3283 3284 case Stmt::IfStmtClass: { 3285 // FIXME: Precompute which side of an 'if' we would jump to, and go 3286 // straight there rather than scanning both sides. 3287 const IfStmt *IS = cast<IfStmt>(S); 3288 3289 // Wrap the evaluation in a block scope, in case it's a DeclStmt 3290 // preceded by our switch label. 3291 BlockScopeRAII Scope(Info); 3292 3293 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case); 3294 if (ESR != ESR_CaseNotFound || !IS->getElse()) 3295 return ESR; 3296 return EvaluateStmt(Result, Info, IS->getElse(), Case); 3297 } 3298 3299 case Stmt::WhileStmtClass: { 3300 EvalStmtResult ESR = 3301 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case); 3302 if (ESR != ESR_Continue) 3303 return ESR; 3304 break; 3305 } 3306 3307 case Stmt::ForStmtClass: { 3308 const ForStmt *FS = cast<ForStmt>(S); 3309 EvalStmtResult ESR = 3310 EvaluateLoopBody(Result, Info, FS->getBody(), Case); 3311 if (ESR != ESR_Continue) 3312 return ESR; 3313 if (FS->getInc()) { 3314 FullExpressionRAII IncScope(Info); 3315 if (!EvaluateIgnoredValue(Info, FS->getInc())) 3316 return ESR_Failed; 3317 } 3318 break; 3319 } 3320 3321 case Stmt::DeclStmtClass: 3322 // FIXME: If the variable has initialization that can't be jumped over, 3323 // bail out of any immediately-surrounding compound-statement too. 3324 default: 3325 return ESR_CaseNotFound; 3326 } 3327 } 3328 3329 switch (S->getStmtClass()) { 3330 default: 3331 if (const Expr *E = dyn_cast<Expr>(S)) { 3332 // Don't bother evaluating beyond an expression-statement which couldn't 3333 // be evaluated. 3334 FullExpressionRAII Scope(Info); 3335 if (!EvaluateIgnoredValue(Info, E)) 3336 return ESR_Failed; 3337 return ESR_Succeeded; 3338 } 3339 3340 Info.Diag(S->getLocStart()); 3341 return ESR_Failed; 3342 3343 case Stmt::NullStmtClass: 3344 return ESR_Succeeded; 3345 3346 case Stmt::DeclStmtClass: { 3347 const DeclStmt *DS = cast<DeclStmt>(S); 3348 for (const auto *DclIt : DS->decls()) { 3349 // Each declaration initialization is its own full-expression. 3350 // FIXME: This isn't quite right; if we're performing aggregate 3351 // initialization, each braced subexpression is its own full-expression. 3352 FullExpressionRAII Scope(Info); 3353 if (!EvaluateDecl(Info, DclIt) && !Info.keepEvaluatingAfterFailure()) 3354 return ESR_Failed; 3355 } 3356 return ESR_Succeeded; 3357 } 3358 3359 case Stmt::ReturnStmtClass: { 3360 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue(); 3361 FullExpressionRAII Scope(Info); 3362 if (RetExpr && !Evaluate(Result, Info, RetExpr)) 3363 return ESR_Failed; 3364 return ESR_Returned; 3365 } 3366 3367 case Stmt::CompoundStmtClass: { 3368 BlockScopeRAII Scope(Info); 3369 3370 const CompoundStmt *CS = cast<CompoundStmt>(S); 3371 for (const auto *BI : CS->body()) { 3372 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case); 3373 if (ESR == ESR_Succeeded) 3374 Case = nullptr; 3375 else if (ESR != ESR_CaseNotFound) 3376 return ESR; 3377 } 3378 return Case ? ESR_CaseNotFound : ESR_Succeeded; 3379 } 3380 3381 case Stmt::IfStmtClass: { 3382 const IfStmt *IS = cast<IfStmt>(S); 3383 3384 // Evaluate the condition, as either a var decl or as an expression. 3385 BlockScopeRAII Scope(Info); 3386 bool Cond; 3387 if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond)) 3388 return ESR_Failed; 3389 3390 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) { 3391 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt); 3392 if (ESR != ESR_Succeeded) 3393 return ESR; 3394 } 3395 return ESR_Succeeded; 3396 } 3397 3398 case Stmt::WhileStmtClass: { 3399 const WhileStmt *WS = cast<WhileStmt>(S); 3400 while (true) { 3401 BlockScopeRAII Scope(Info); 3402 bool Continue; 3403 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(), 3404 Continue)) 3405 return ESR_Failed; 3406 if (!Continue) 3407 break; 3408 3409 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody()); 3410 if (ESR != ESR_Continue) 3411 return ESR; 3412 } 3413 return ESR_Succeeded; 3414 } 3415 3416 case Stmt::DoStmtClass: { 3417 const DoStmt *DS = cast<DoStmt>(S); 3418 bool Continue; 3419 do { 3420 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case); 3421 if (ESR != ESR_Continue) 3422 return ESR; 3423 Case = nullptr; 3424 3425 FullExpressionRAII CondScope(Info); 3426 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info)) 3427 return ESR_Failed; 3428 } while (Continue); 3429 return ESR_Succeeded; 3430 } 3431 3432 case Stmt::ForStmtClass: { 3433 const ForStmt *FS = cast<ForStmt>(S); 3434 BlockScopeRAII Scope(Info); 3435 if (FS->getInit()) { 3436 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); 3437 if (ESR != ESR_Succeeded) 3438 return ESR; 3439 } 3440 while (true) { 3441 BlockScopeRAII Scope(Info); 3442 bool Continue = true; 3443 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(), 3444 FS->getCond(), Continue)) 3445 return ESR_Failed; 3446 if (!Continue) 3447 break; 3448 3449 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody()); 3450 if (ESR != ESR_Continue) 3451 return ESR; 3452 3453 if (FS->getInc()) { 3454 FullExpressionRAII IncScope(Info); 3455 if (!EvaluateIgnoredValue(Info, FS->getInc())) 3456 return ESR_Failed; 3457 } 3458 } 3459 return ESR_Succeeded; 3460 } 3461 3462 case Stmt::CXXForRangeStmtClass: { 3463 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S); 3464 BlockScopeRAII Scope(Info); 3465 3466 // Initialize the __range variable. 3467 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt()); 3468 if (ESR != ESR_Succeeded) 3469 return ESR; 3470 3471 // Create the __begin and __end iterators. 3472 ESR = EvaluateStmt(Result, Info, FS->getBeginEndStmt()); 3473 if (ESR != ESR_Succeeded) 3474 return ESR; 3475 3476 while (true) { 3477 // Condition: __begin != __end. 3478 { 3479 bool Continue = true; 3480 FullExpressionRAII CondExpr(Info); 3481 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info)) 3482 return ESR_Failed; 3483 if (!Continue) 3484 break; 3485 } 3486 3487 // User's variable declaration, initialized by *__begin. 3488 BlockScopeRAII InnerScope(Info); 3489 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt()); 3490 if (ESR != ESR_Succeeded) 3491 return ESR; 3492 3493 // Loop body. 3494 ESR = EvaluateLoopBody(Result, Info, FS->getBody()); 3495 if (ESR != ESR_Continue) 3496 return ESR; 3497 3498 // Increment: ++__begin 3499 if (!EvaluateIgnoredValue(Info, FS->getInc())) 3500 return ESR_Failed; 3501 } 3502 3503 return ESR_Succeeded; 3504 } 3505 3506 case Stmt::SwitchStmtClass: 3507 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S)); 3508 3509 case Stmt::ContinueStmtClass: 3510 return ESR_Continue; 3511 3512 case Stmt::BreakStmtClass: 3513 return ESR_Break; 3514 3515 case Stmt::LabelStmtClass: 3516 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case); 3517 3518 case Stmt::AttributedStmtClass: 3519 // As a general principle, C++11 attributes can be ignored without 3520 // any semantic impact. 3521 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(), 3522 Case); 3523 3524 case Stmt::CaseStmtClass: 3525 case Stmt::DefaultStmtClass: 3526 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case); 3527 } 3528} 3529 3530/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial 3531/// default constructor. If so, we'll fold it whether or not it's marked as 3532/// constexpr. If it is marked as constexpr, we will never implicitly define it, 3533/// so we need special handling. 3534static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc, 3535 const CXXConstructorDecl *CD, 3536 bool IsValueInitialization) { 3537 if (!CD->isTrivial() || !CD->isDefaultConstructor()) 3538 return false; 3539 3540 // Value-initialization does not call a trivial default constructor, so such a 3541 // call is a core constant expression whether or not the constructor is 3542 // constexpr. 3543 if (!CD->isConstexpr() && !IsValueInitialization) { 3544 if (Info.getLangOpts().CPlusPlus11) { 3545 // FIXME: If DiagDecl is an implicitly-declared special member function, 3546 // we should be much more explicit about why it's not constexpr. 3547 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1) 3548 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD; 3549 Info.Note(CD->getLocation(), diag::note_declared_at); 3550 } else { 3551 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr); 3552 } 3553 } 3554 return true; 3555} 3556 3557/// CheckConstexprFunction - Check that a function can be called in a constant 3558/// expression. 3559static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc, 3560 const FunctionDecl *Declaration, 3561 const FunctionDecl *Definition) { 3562 // Potential constant expressions can contain calls to declared, but not yet 3563 // defined, constexpr functions. 3564 if (Info.checkingPotentialConstantExpression() && !Definition && 3565 Declaration->isConstexpr()) 3566 return false; 3567 3568 // Bail out with no diagnostic if the function declaration itself is invalid. 3569 // We will have produced a relevant diagnostic while parsing it. 3570 if (Declaration->isInvalidDecl()) 3571 return false; 3572 3573 // Can we evaluate this function call? 3574 if (Definition && Definition->isConstexpr() && !Definition->isInvalidDecl()) 3575 return true; 3576 3577 if (Info.getLangOpts().CPlusPlus11) { 3578 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration; 3579 // FIXME: If DiagDecl is an implicitly-declared special member function, we 3580 // should be much more explicit about why it's not constexpr. 3581 Info.Diag(CallLoc, diag::note_constexpr_invalid_function, 1) 3582 << DiagDecl->isConstexpr() << isa<CXXConstructorDecl>(DiagDecl) 3583 << DiagDecl; 3584 Info.Note(DiagDecl->getLocation(), diag::note_declared_at); 3585 } else { 3586 Info.Diag(CallLoc, diag::note_invalid_subexpr_in_const_expr); 3587 } 3588 return false; 3589} 3590 3591namespace { 3592typedef SmallVector<APValue, 8> ArgVector; 3593} 3594 3595/// EvaluateArgs - Evaluate the arguments to a function call. 3596static bool EvaluateArgs(ArrayRef<const Expr*> Args, ArgVector &ArgValues, 3597 EvalInfo &Info) { 3598 bool Success = true; 3599 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end(); 3600 I != E; ++I) { 3601 if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) { 3602 // If we're checking for a potential constant expression, evaluate all 3603 // initializers even if some of them fail. 3604 if (!Info.keepEvaluatingAfterFailure()) 3605 return false; 3606 Success = false; 3607 } 3608 } 3609 return Success; 3610} 3611 3612/// Evaluate a function call. 3613static bool HandleFunctionCall(SourceLocation CallLoc, 3614 const FunctionDecl *Callee, const LValue *This, 3615 ArrayRef<const Expr*> Args, const Stmt *Body, 3616 EvalInfo &Info, APValue &Result) { 3617 ArgVector ArgValues(Args.size()); 3618 if (!EvaluateArgs(Args, ArgValues, Info)) 3619 return false; 3620 3621 if (!Info.CheckCallLimit(CallLoc)) 3622 return false; 3623 3624 CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data()); 3625 3626 // For a trivial copy or move assignment, perform an APValue copy. This is 3627 // essential for unions, where the operations performed by the assignment 3628 // operator cannot be represented as statements. 3629 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee); 3630 if (MD && MD->isDefaulted() && MD->isTrivial()) { 3631 assert(This && 3632 (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())); 3633 LValue RHS; 3634 RHS.setFrom(Info.Ctx, ArgValues[0]); 3635 APValue RHSValue; 3636 if (!handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), 3637 RHS, RHSValue)) 3638 return false; 3639 if (!handleAssignment(Info, Args[0], *This, MD->getThisType(Info.Ctx), 3640 RHSValue)) 3641 return false; 3642 This->moveInto(Result); 3643 return true; 3644 } 3645 3646 EvalStmtResult ESR = EvaluateStmt(Result, Info, Body); 3647 if (ESR == ESR_Succeeded) { 3648 if (Callee->getReturnType()->isVoidType()) 3649 return true; 3650 Info.Diag(Callee->getLocEnd(), diag::note_constexpr_no_return); 3651 } 3652 return ESR == ESR_Returned; 3653} 3654 3655/// Evaluate a constructor call. 3656static bool HandleConstructorCall(SourceLocation CallLoc, const LValue &This, 3657 ArrayRef<const Expr*> Args, 3658 const CXXConstructorDecl *Definition, 3659 EvalInfo &Info, APValue &Result) { 3660 ArgVector ArgValues(Args.size()); 3661 if (!EvaluateArgs(Args, ArgValues, Info)) 3662 return false; 3663 3664 if (!Info.CheckCallLimit(CallLoc)) 3665 return false; 3666 3667 const CXXRecordDecl *RD = Definition->getParent(); 3668 if (RD->getNumVBases()) { 3669 Info.Diag(CallLoc, diag::note_constexpr_virtual_base) << RD; 3670 return false; 3671 } 3672 3673 CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues.data()); 3674 3675 // If it's a delegating constructor, just delegate. 3676 if (Definition->isDelegatingConstructor()) { 3677 CXXConstructorDecl::init_const_iterator I = Definition->init_begin(); 3678 { 3679 FullExpressionRAII InitScope(Info); 3680 if (!EvaluateInPlace(Result, Info, This, (*I)->getInit())) 3681 return false; 3682 } 3683 return EvaluateStmt(Result, Info, Definition->getBody()) != ESR_Failed; 3684 } 3685 3686 // For a trivial copy or move constructor, perform an APValue copy. This is 3687 // essential for unions, where the operations performed by the constructor 3688 // cannot be represented by ctor-initializers. 3689 if (Definition->isDefaulted() && 3690 ((Definition->isCopyConstructor() && Definition->isTrivial()) || 3691 (Definition->isMoveConstructor() && Definition->isTrivial()))) { 3692 LValue RHS; 3693 RHS.setFrom(Info.Ctx, ArgValues[0]); 3694 return handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), 3695 RHS, Result); 3696 } 3697 3698 // Reserve space for the struct members. 3699 if (!RD->isUnion() && Result.isUninit()) 3700 Result = APValue(APValue::UninitStruct(), RD->getNumBases(), 3701 std::distance(RD->field_begin(), RD->field_end())); 3702 3703 if (RD->isInvalidDecl()) return false; 3704 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 3705 3706 // A scope for temporaries lifetime-extended by reference members. 3707 BlockScopeRAII LifetimeExtendedScope(Info); 3708 3709 bool Success = true; 3710 unsigned BasesSeen = 0; 3711#ifndef NDEBUG 3712 CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin(); 3713#endif 3714 for (const auto *I : Definition->inits()) { 3715 LValue Subobject = This; 3716 APValue *Value = &Result; 3717 3718 // Determine the subobject to initialize. 3719 FieldDecl *FD = nullptr; 3720 if (I->isBaseInitializer()) { 3721 QualType BaseType(I->getBaseClass(), 0); 3722#ifndef NDEBUG 3723 // Non-virtual base classes are initialized in the order in the class 3724 // definition. We have already checked for virtual base classes. 3725 assert(!BaseIt->isVirtual() && "virtual base for literal type"); 3726 assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && 3727 "base class initializers not in expected order"); 3728 ++BaseIt; 3729#endif 3730 if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD, 3731 BaseType->getAsCXXRecordDecl(), &Layout)) 3732 return false; 3733 Value = &Result.getStructBase(BasesSeen++); 3734 } else if ((FD = I->getMember())) { 3735 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout)) 3736 return false; 3737 if (RD->isUnion()) { 3738 Result = APValue(FD); 3739 Value = &Result.getUnionValue(); 3740 } else { 3741 Value = &Result.getStructField(FD->getFieldIndex()); 3742 } 3743 } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) { 3744 // Walk the indirect field decl's chain to find the object to initialize, 3745 // and make sure we've initialized every step along it. 3746 for (auto *C : IFD->chain()) { 3747 FD = cast<FieldDecl>(C); 3748 CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent()); 3749 // Switch the union field if it differs. This happens if we had 3750 // preceding zero-initialization, and we're now initializing a union 3751 // subobject other than the first. 3752 // FIXME: In this case, the values of the other subobjects are 3753 // specified, since zero-initialization sets all padding bits to zero. 3754 if (Value->isUninit() || 3755 (Value->isUnion() && Value->getUnionField() != FD)) { 3756 if (CD->isUnion()) 3757 *Value = APValue(FD); 3758 else 3759 *Value = APValue(APValue::UninitStruct(), CD->getNumBases(), 3760 std::distance(CD->field_begin(), CD->field_end())); 3761 } 3762 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD)) 3763 return false; 3764 if (CD->isUnion()) 3765 Value = &Value->getUnionValue(); 3766 else 3767 Value = &Value->getStructField(FD->getFieldIndex()); 3768 } 3769 } else { 3770 llvm_unreachable("unknown base initializer kind"); 3771 } 3772 3773 FullExpressionRAII InitScope(Info); 3774 if (!EvaluateInPlace(*Value, Info, Subobject, I->getInit()) || 3775 (FD && FD->isBitField() && !truncateBitfieldValue(Info, I->getInit(), 3776 *Value, FD))) { 3777 // If we're checking for a potential constant expression, evaluate all 3778 // initializers even if some of them fail. 3779 if (!Info.keepEvaluatingAfterFailure()) 3780 return false; 3781 Success = false; 3782 } 3783 } 3784 3785 return Success && 3786 EvaluateStmt(Result, Info, Definition->getBody()) != ESR_Failed; 3787} 3788 3789//===----------------------------------------------------------------------===// 3790// Generic Evaluation 3791//===----------------------------------------------------------------------===// 3792namespace { 3793 3794template <class Derived> 3795class ExprEvaluatorBase 3796 : public ConstStmtVisitor<Derived, bool> { 3797private: 3798 bool DerivedSuccess(const APValue &V, const Expr *E) { 3799 return static_cast<Derived*>(this)->Success(V, E); 3800 } 3801 bool DerivedZeroInitialization(const Expr *E) { 3802 return static_cast<Derived*>(this)->ZeroInitialization(E); 3803 } 3804 3805 // Check whether a conditional operator with a non-constant condition is a 3806 // potential constant expression. If neither arm is a potential constant 3807 // expression, then the conditional operator is not either. 3808 template<typename ConditionalOperator> 3809 void CheckPotentialConstantConditional(const ConditionalOperator *E) { 3810 assert(Info.checkingPotentialConstantExpression()); 3811 3812 // Speculatively evaluate both arms. 3813 { 3814 SmallVector<PartialDiagnosticAt, 8> Diag; 3815 SpeculativeEvaluationRAII Speculate(Info, &Diag); 3816 3817 StmtVisitorTy::Visit(E->getFalseExpr()); 3818 if (Diag.empty()) 3819 return; 3820 3821 Diag.clear(); 3822 StmtVisitorTy::Visit(E->getTrueExpr()); 3823 if (Diag.empty()) 3824 return; 3825 } 3826 3827 Error(E, diag::note_constexpr_conditional_never_const); 3828 } 3829 3830 3831 template<typename ConditionalOperator> 3832 bool HandleConditionalOperator(const ConditionalOperator *E) { 3833 bool BoolResult; 3834 if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) { 3835 if (Info.checkingPotentialConstantExpression()) 3836 CheckPotentialConstantConditional(E); 3837 return false; 3838 } 3839 3840 Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr(); 3841 return StmtVisitorTy::Visit(EvalExpr); 3842 } 3843 3844protected: 3845 EvalInfo &Info; 3846 typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy; 3847 typedef ExprEvaluatorBase ExprEvaluatorBaseTy; 3848 3849 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { 3850 return Info.CCEDiag(E, D); 3851 } 3852 3853 bool ZeroInitialization(const Expr *E) { return Error(E); } 3854 3855public: 3856 ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {} 3857 3858 EvalInfo &getEvalInfo() { return Info; } 3859 3860 /// Report an evaluation error. This should only be called when an error is 3861 /// first discovered. When propagating an error, just return false. 3862 bool Error(const Expr *E, diag::kind D) { 3863 Info.Diag(E, D); 3864 return false; 3865 } 3866 bool Error(const Expr *E) { 3867 return Error(E, diag::note_invalid_subexpr_in_const_expr); 3868 } 3869 3870 bool VisitStmt(const Stmt *) { 3871 llvm_unreachable("Expression evaluator should not be called on stmts"); 3872 } 3873 bool VisitExpr(const Expr *E) { 3874 return Error(E); 3875 } 3876 3877 bool VisitParenExpr(const ParenExpr *E) 3878 { return StmtVisitorTy::Visit(E->getSubExpr()); } 3879 bool VisitUnaryExtension(const UnaryOperator *E) 3880 { return StmtVisitorTy::Visit(E->getSubExpr()); } 3881 bool VisitUnaryPlus(const UnaryOperator *E) 3882 { return StmtVisitorTy::Visit(E->getSubExpr()); } 3883 bool VisitChooseExpr(const ChooseExpr *E) 3884 { return StmtVisitorTy::Visit(E->getChosenSubExpr()); } 3885 bool VisitGenericSelectionExpr(const GenericSelectionExpr *E) 3886 { return StmtVisitorTy::Visit(E->getResultExpr()); } 3887 bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E) 3888 { return StmtVisitorTy::Visit(E->getReplacement()); } 3889 bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) 3890 { return StmtVisitorTy::Visit(E->getExpr()); } 3891 bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) { 3892 // The initializer may not have been parsed yet, or might be erroneous. 3893 if (!E->getExpr()) 3894 return Error(E); 3895 return StmtVisitorTy::Visit(E->getExpr()); 3896 } 3897 // We cannot create any objects for which cleanups are required, so there is 3898 // nothing to do here; all cleanups must come from unevaluated subexpressions. 3899 bool VisitExprWithCleanups(const ExprWithCleanups *E) 3900 { return StmtVisitorTy::Visit(E->getSubExpr()); } 3901 3902 bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) { 3903 CCEDiag(E, diag::note_constexpr_invalid_cast) << 0; 3904 return static_cast<Derived*>(this)->VisitCastExpr(E); 3905 } 3906 bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) { 3907 CCEDiag(E, diag::note_constexpr_invalid_cast) << 1; 3908 return static_cast<Derived*>(this)->VisitCastExpr(E); 3909 } 3910 3911 bool VisitBinaryOperator(const BinaryOperator *E) { 3912 switch (E->getOpcode()) { 3913 default: 3914 return Error(E); 3915 3916 case BO_Comma: 3917 VisitIgnoredValue(E->getLHS()); 3918 return StmtVisitorTy::Visit(E->getRHS()); 3919 3920 case BO_PtrMemD: 3921 case BO_PtrMemI: { 3922 LValue Obj; 3923 if (!HandleMemberPointerAccess(Info, E, Obj)) 3924 return false; 3925 APValue Result; 3926 if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result)) 3927 return false; 3928 return DerivedSuccess(Result, E); 3929 } 3930 } 3931 } 3932 3933 bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) { 3934 // Evaluate and cache the common expression. We treat it as a temporary, 3935 // even though it's not quite the same thing. 3936 if (!Evaluate(Info.CurrentCall->createTemporary(E->getOpaqueValue(), false), 3937 Info, E->getCommon())) 3938 return false; 3939 3940 return HandleConditionalOperator(E); 3941 } 3942 3943 bool VisitConditionalOperator(const ConditionalOperator *E) { 3944 bool IsBcpCall = false; 3945 // If the condition (ignoring parens) is a __builtin_constant_p call, 3946 // the result is a constant expression if it can be folded without 3947 // side-effects. This is an important GNU extension. See GCC PR38377 3948 // for discussion. 3949 if (const CallExpr *CallCE = 3950 dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts())) 3951 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) 3952 IsBcpCall = true; 3953 3954 // Always assume __builtin_constant_p(...) ? ... : ... is a potential 3955 // constant expression; we can't check whether it's potentially foldable. 3956 if (Info.checkingPotentialConstantExpression() && IsBcpCall) 3957 return false; 3958 3959 FoldConstant Fold(Info, IsBcpCall); 3960 if (!HandleConditionalOperator(E)) { 3961 Fold.keepDiagnostics(); 3962 return false; 3963 } 3964 3965 return true; 3966 } 3967 3968 bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) { 3969 if (APValue *Value = Info.CurrentCall->getTemporary(E)) 3970 return DerivedSuccess(*Value, E); 3971 3972 const Expr *Source = E->getSourceExpr(); 3973 if (!Source) 3974 return Error(E); 3975 if (Source == E) { // sanity checking. 3976 assert(0 && "OpaqueValueExpr recursively refers to itself"); 3977 return Error(E); 3978 } 3979 return StmtVisitorTy::Visit(Source); 3980 } 3981 3982 bool VisitCallExpr(const CallExpr *E) { 3983 const Expr *Callee = E->getCallee()->IgnoreParens(); 3984 QualType CalleeType = Callee->getType(); 3985 3986 const FunctionDecl *FD = nullptr; 3987 LValue *This = nullptr, ThisVal; 3988 ArrayRef<const Expr *> Args(E->getArgs(), E->getNumArgs()); 3989 bool HasQualifier = false; 3990 3991 // Extract function decl and 'this' pointer from the callee. 3992 if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) { 3993 const ValueDecl *Member = nullptr; 3994 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) { 3995 // Explicit bound member calls, such as x.f() or p->g(); 3996 if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal)) 3997 return false; 3998 Member = ME->getMemberDecl(); 3999 This = &ThisVal; 4000 HasQualifier = ME->hasQualifier(); 4001 } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) { 4002 // Indirect bound member calls ('.*' or '->*'). 4003 Member = HandleMemberPointerAccess(Info, BE, ThisVal, false); 4004 if (!Member) return false; 4005 This = &ThisVal; 4006 } else 4007 return Error(Callee); 4008 4009 FD = dyn_cast<FunctionDecl>(Member); 4010 if (!FD) 4011 return Error(Callee); 4012 } else if (CalleeType->isFunctionPointerType()) { 4013 LValue Call; 4014 if (!EvaluatePointer(Callee, Call, Info)) 4015 return false; 4016 4017 if (!Call.getLValueOffset().isZero()) 4018 return Error(Callee); 4019 FD = dyn_cast_or_null<FunctionDecl>( 4020 Call.getLValueBase().dyn_cast<const ValueDecl*>()); 4021 if (!FD) 4022 return Error(Callee); 4023 4024 // Overloaded operator calls to member functions are represented as normal 4025 // calls with '*this' as the first argument. 4026 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); 4027 if (MD && !MD->isStatic()) { 4028 // FIXME: When selecting an implicit conversion for an overloaded 4029 // operator delete, we sometimes try to evaluate calls to conversion 4030 // operators without a 'this' parameter! 4031 if (Args.empty()) 4032 return Error(E); 4033 4034 if (!EvaluateObjectArgument(Info, Args[0], ThisVal)) 4035 return false; 4036 This = &ThisVal; 4037 Args = Args.slice(1); 4038 } 4039 4040 // Don't call function pointers which have been cast to some other type. 4041 if (!Info.Ctx.hasSameType(CalleeType->getPointeeType(), FD->getType())) 4042 return Error(E); 4043 } else 4044 return Error(E); 4045 4046 if (This && !This->checkSubobject(Info, E, CSK_This)) 4047 return false; 4048 4049 // DR1358 allows virtual constexpr functions in some cases. Don't allow 4050 // calls to such functions in constant expressions. 4051 if (This && !HasQualifier && 4052 isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isVirtual()) 4053 return Error(E, diag::note_constexpr_virtual_call); 4054 4055 const FunctionDecl *Definition = nullptr; 4056 Stmt *Body = FD->getBody(Definition); 4057 APValue Result; 4058 4059 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition) || 4060 !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, 4061 Info, Result)) 4062 return false; 4063 4064 return DerivedSuccess(Result, E); 4065 } 4066 4067 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { 4068 return StmtVisitorTy::Visit(E->getInitializer()); 4069 } 4070 bool VisitInitListExpr(const InitListExpr *E) { 4071 if (E->getNumInits() == 0) 4072 return DerivedZeroInitialization(E); 4073 if (E->getNumInits() == 1) 4074 return StmtVisitorTy::Visit(E->getInit(0)); 4075 return Error(E); 4076 } 4077 bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) { 4078 return DerivedZeroInitialization(E); 4079 } 4080 bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) { 4081 return DerivedZeroInitialization(E); 4082 } 4083 bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) { 4084 return DerivedZeroInitialization(E); 4085 } 4086 4087 /// A member expression where the object is a prvalue is itself a prvalue. 4088 bool VisitMemberExpr(const MemberExpr *E) { 4089 assert(!E->isArrow() && "missing call to bound member function?"); 4090 4091 APValue Val; 4092 if (!Evaluate(Val, Info, E->getBase())) 4093 return false; 4094 4095 QualType BaseTy = E->getBase()->getType(); 4096 4097 const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl()); 4098 if (!FD) return Error(E); 4099 assert(!FD->getType()->isReferenceType() && "prvalue reference?"); 4100 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == 4101 FD->getParent()->getCanonicalDecl() && "record / field mismatch"); 4102 4103 CompleteObject Obj(&Val, BaseTy); 4104 SubobjectDesignator Designator(BaseTy); 4105 Designator.addDeclUnchecked(FD); 4106 4107 APValue Result; 4108 return extractSubobject(Info, E, Obj, Designator, Result) && 4109 DerivedSuccess(Result, E); 4110 } 4111 4112 bool VisitCastExpr(const CastExpr *E) { 4113 switch (E->getCastKind()) { 4114 default: 4115 break; 4116 4117 case CK_AtomicToNonAtomic: { 4118 APValue AtomicVal; 4119 if (!EvaluateAtomic(E->getSubExpr(), AtomicVal, Info)) 4120 return false; 4121 return DerivedSuccess(AtomicVal, E); 4122 } 4123 4124 case CK_NoOp: 4125 case CK_UserDefinedConversion: 4126 return StmtVisitorTy::Visit(E->getSubExpr()); 4127 4128 case CK_LValueToRValue: { 4129 LValue LVal; 4130 if (!EvaluateLValue(E->getSubExpr(), LVal, Info)) 4131 return false; 4132 APValue RVal; 4133 // Note, we use the subexpression's type in order to retain cv-qualifiers. 4134 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(), 4135 LVal, RVal)) 4136 return false; 4137 return DerivedSuccess(RVal, E); 4138 } 4139 } 4140 4141 return Error(E); 4142 } 4143 4144 bool VisitUnaryPostInc(const UnaryOperator *UO) { 4145 return VisitUnaryPostIncDec(UO); 4146 } 4147 bool VisitUnaryPostDec(const UnaryOperator *UO) { 4148 return VisitUnaryPostIncDec(UO); 4149 } 4150 bool VisitUnaryPostIncDec(const UnaryOperator *UO) { 4151 if (!Info.getLangOpts().CPlusPlus1y && !Info.keepEvaluatingAfterFailure()) 4152 return Error(UO); 4153 4154 LValue LVal; 4155 if (!EvaluateLValue(UO->getSubExpr(), LVal, Info)) 4156 return false; 4157 APValue RVal; 4158 if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(), 4159 UO->isIncrementOp(), &RVal)) 4160 return false; 4161 return DerivedSuccess(RVal, UO); 4162 } 4163 4164 bool VisitStmtExpr(const StmtExpr *E) { 4165 // We will have checked the full-expressions inside the statement expression 4166 // when they were completed, and don't need to check them again now. 4167 if (Info.checkingForOverflow()) 4168 return Error(E); 4169 4170 BlockScopeRAII Scope(Info); 4171 const CompoundStmt *CS = E->getSubStmt(); 4172 for (CompoundStmt::const_body_iterator BI = CS->body_begin(), 4173 BE = CS->body_end(); 4174 /**/; ++BI) { 4175 if (BI + 1 == BE) { 4176 const Expr *FinalExpr = dyn_cast<Expr>(*BI); 4177 if (!FinalExpr) { 4178 Info.Diag((*BI)->getLocStart(), 4179 diag::note_constexpr_stmt_expr_unsupported); 4180 return false; 4181 } 4182 return this->Visit(FinalExpr); 4183 } 4184 4185 APValue ReturnValue; 4186 EvalStmtResult ESR = EvaluateStmt(ReturnValue, Info, *BI); 4187 if (ESR != ESR_Succeeded) { 4188 // FIXME: If the statement-expression terminated due to 'return', 4189 // 'break', or 'continue', it would be nice to propagate that to 4190 // the outer statement evaluation rather than bailing out. 4191 if (ESR != ESR_Failed) 4192 Info.Diag((*BI)->getLocStart(), 4193 diag::note_constexpr_stmt_expr_unsupported); 4194 return false; 4195 } 4196 } 4197 } 4198 4199 /// Visit a value which is evaluated, but whose value is ignored. 4200 void VisitIgnoredValue(const Expr *E) { 4201 EvaluateIgnoredValue(Info, E); 4202 } 4203}; 4204 4205} 4206 4207//===----------------------------------------------------------------------===// 4208// Common base class for lvalue and temporary evaluation. 4209//===----------------------------------------------------------------------===// 4210namespace { 4211template<class Derived> 4212class LValueExprEvaluatorBase 4213 : public ExprEvaluatorBase<Derived> { 4214protected: 4215 LValue &Result; 4216 typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy; 4217 typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy; 4218 4219 bool Success(APValue::LValueBase B) { 4220 Result.set(B); 4221 return true; 4222 } 4223 4224public: 4225 LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result) : 4226 ExprEvaluatorBaseTy(Info), Result(Result) {} 4227 4228 bool Success(const APValue &V, const Expr *E) { 4229 Result.setFrom(this->Info.Ctx, V); 4230 return true; 4231 } 4232 4233 bool VisitMemberExpr(const MemberExpr *E) { 4234 // Handle non-static data members. 4235 QualType BaseTy; 4236 if (E->isArrow()) { 4237 if (!EvaluatePointer(E->getBase(), Result, this->Info)) 4238 return false; 4239 BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType(); 4240 } else if (E->getBase()->isRValue()) { 4241 assert(E->getBase()->getType()->isRecordType()); 4242 if (!EvaluateTemporary(E->getBase(), Result, this->Info)) 4243 return false; 4244 BaseTy = E->getBase()->getType(); 4245 } else { 4246 if (!this->Visit(E->getBase())) 4247 return false; 4248 BaseTy = E->getBase()->getType(); 4249 } 4250 4251 const ValueDecl *MD = E->getMemberDecl(); 4252 if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) { 4253 assert(BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() == 4254 FD->getParent()->getCanonicalDecl() && "record / field mismatch"); 4255 (void)BaseTy; 4256 if (!HandleLValueMember(this->Info, E, Result, FD)) 4257 return false; 4258 } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) { 4259 if (!HandleLValueIndirectMember(this->Info, E, Result, IFD)) 4260 return false; 4261 } else 4262 return this->Error(E); 4263 4264 if (MD->getType()->isReferenceType()) { 4265 APValue RefValue; 4266 if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result, 4267 RefValue)) 4268 return false; 4269 return Success(RefValue, E); 4270 } 4271 return true; 4272 } 4273 4274 bool VisitBinaryOperator(const BinaryOperator *E) { 4275 switch (E->getOpcode()) { 4276 default: 4277 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 4278 4279 case BO_PtrMemD: 4280 case BO_PtrMemI: 4281 return HandleMemberPointerAccess(this->Info, E, Result); 4282 } 4283 } 4284 4285 bool VisitCastExpr(const CastExpr *E) { 4286 switch (E->getCastKind()) { 4287 default: 4288 return ExprEvaluatorBaseTy::VisitCastExpr(E); 4289 4290 case CK_DerivedToBase: 4291 case CK_UncheckedDerivedToBase: 4292 if (!this->Visit(E->getSubExpr())) 4293 return false; 4294 4295 // Now figure out the necessary offset to add to the base LV to get from 4296 // the derived class to the base class. 4297 return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(), 4298 Result); 4299 } 4300 } 4301}; 4302} 4303 4304//===----------------------------------------------------------------------===// 4305// LValue Evaluation 4306// 4307// This is used for evaluating lvalues (in C and C++), xvalues (in C++11), 4308// function designators (in C), decl references to void objects (in C), and 4309// temporaries (if building with -Wno-address-of-temporary). 4310// 4311// LValue evaluation produces values comprising a base expression of one of the 4312// following types: 4313// - Declarations 4314// * VarDecl 4315// * FunctionDecl 4316// - Literals 4317// * CompoundLiteralExpr in C 4318// * StringLiteral 4319// * CXXTypeidExpr 4320// * PredefinedExpr 4321// * ObjCStringLiteralExpr 4322// * ObjCEncodeExpr 4323// * AddrLabelExpr 4324// * BlockExpr 4325// * CallExpr for a MakeStringConstant builtin 4326// - Locals and temporaries 4327// * MaterializeTemporaryExpr 4328// * Any Expr, with a CallIndex indicating the function in which the temporary 4329// was evaluated, for cases where the MaterializeTemporaryExpr is missing 4330// from the AST (FIXME). 4331// * A MaterializeTemporaryExpr that has static storage duration, with no 4332// CallIndex, for a lifetime-extended temporary. 4333// plus an offset in bytes. 4334//===----------------------------------------------------------------------===// 4335namespace { 4336class LValueExprEvaluator 4337 : public LValueExprEvaluatorBase<LValueExprEvaluator> { 4338public: 4339 LValueExprEvaluator(EvalInfo &Info, LValue &Result) : 4340 LValueExprEvaluatorBaseTy(Info, Result) {} 4341 4342 bool VisitVarDecl(const Expr *E, const VarDecl *VD); 4343 bool VisitUnaryPreIncDec(const UnaryOperator *UO); 4344 4345 bool VisitDeclRefExpr(const DeclRefExpr *E); 4346 bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); } 4347 bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E); 4348 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E); 4349 bool VisitMemberExpr(const MemberExpr *E); 4350 bool VisitStringLiteral(const StringLiteral *E) { return Success(E); } 4351 bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); } 4352 bool VisitCXXTypeidExpr(const CXXTypeidExpr *E); 4353 bool VisitCXXUuidofExpr(const CXXUuidofExpr *E); 4354 bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E); 4355 bool VisitUnaryDeref(const UnaryOperator *E); 4356 bool VisitUnaryReal(const UnaryOperator *E); 4357 bool VisitUnaryImag(const UnaryOperator *E); 4358 bool VisitUnaryPreInc(const UnaryOperator *UO) { 4359 return VisitUnaryPreIncDec(UO); 4360 } 4361 bool VisitUnaryPreDec(const UnaryOperator *UO) { 4362 return VisitUnaryPreIncDec(UO); 4363 } 4364 bool VisitBinAssign(const BinaryOperator *BO); 4365 bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO); 4366 4367 bool VisitCastExpr(const CastExpr *E) { 4368 switch (E->getCastKind()) { 4369 default: 4370 return LValueExprEvaluatorBaseTy::VisitCastExpr(E); 4371 4372 case CK_LValueBitCast: 4373 this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 4374 if (!Visit(E->getSubExpr())) 4375 return false; 4376 Result.Designator.setInvalid(); 4377 return true; 4378 4379 case CK_BaseToDerived: 4380 if (!Visit(E->getSubExpr())) 4381 return false; 4382 return HandleBaseToDerivedCast(Info, E, Result); 4383 } 4384 } 4385}; 4386} // end anonymous namespace 4387 4388/// Evaluate an expression as an lvalue. This can be legitimately called on 4389/// expressions which are not glvalues, in two cases: 4390/// * function designators in C, and 4391/// * "extern void" objects 4392static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info) { 4393 assert(E->isGLValue() || E->getType()->isFunctionType() || 4394 E->getType()->isVoidType()); 4395 return LValueExprEvaluator(Info, Result).Visit(E); 4396} 4397 4398bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) { 4399 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl())) 4400 return Success(FD); 4401 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl())) 4402 return VisitVarDecl(E, VD); 4403 return Error(E); 4404} 4405 4406bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) { 4407 CallStackFrame *Frame = nullptr; 4408 if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) 4409 Frame = Info.CurrentCall; 4410 4411 if (!VD->getType()->isReferenceType()) { 4412 if (Frame) { 4413 Result.set(VD, Frame->Index); 4414 return true; 4415 } 4416 return Success(VD); 4417 } 4418 4419 APValue *V; 4420 if (!evaluateVarDeclInit(Info, E, VD, Frame, V)) 4421 return false; 4422 if (V->isUninit()) { 4423 if (!Info.checkingPotentialConstantExpression()) 4424 Info.Diag(E, diag::note_constexpr_use_uninit_reference); 4425 return false; 4426 } 4427 return Success(*V, E); 4428} 4429 4430bool LValueExprEvaluator::VisitMaterializeTemporaryExpr( 4431 const MaterializeTemporaryExpr *E) { 4432 // Walk through the expression to find the materialized temporary itself. 4433 SmallVector<const Expr *, 2> CommaLHSs; 4434 SmallVector<SubobjectAdjustment, 2> Adjustments; 4435 const Expr *Inner = E->GetTemporaryExpr()-> 4436 skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); 4437 4438 // If we passed any comma operators, evaluate their LHSs. 4439 for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I) 4440 if (!EvaluateIgnoredValue(Info, CommaLHSs[I])) 4441 return false; 4442 4443 // A materialized temporary with static storage duration can appear within the 4444 // result of a constant expression evaluation, so we need to preserve its 4445 // value for use outside this evaluation. 4446 APValue *Value; 4447 if (E->getStorageDuration() == SD_Static) { 4448 Value = Info.Ctx.getMaterializedTemporaryValue(E, true); 4449 *Value = APValue(); 4450 Result.set(E); 4451 } else { 4452 Value = &Info.CurrentCall-> 4453 createTemporary(E, E->getStorageDuration() == SD_Automatic); 4454 Result.set(E, Info.CurrentCall->Index); 4455 } 4456 4457 QualType Type = Inner->getType(); 4458 4459 // Materialize the temporary itself. 4460 if (!EvaluateInPlace(*Value, Info, Result, Inner) || 4461 (E->getStorageDuration() == SD_Static && 4462 !CheckConstantExpression(Info, E->getExprLoc(), Type, *Value))) { 4463 *Value = APValue(); 4464 return false; 4465 } 4466 4467 // Adjust our lvalue to refer to the desired subobject. 4468 for (unsigned I = Adjustments.size(); I != 0; /**/) { 4469 --I; 4470 switch (Adjustments[I].Kind) { 4471 case SubobjectAdjustment::DerivedToBaseAdjustment: 4472 if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath, 4473 Type, Result)) 4474 return false; 4475 Type = Adjustments[I].DerivedToBase.BasePath->getType(); 4476 break; 4477 4478 case SubobjectAdjustment::FieldAdjustment: 4479 if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field)) 4480 return false; 4481 Type = Adjustments[I].Field->getType(); 4482 break; 4483 4484 case SubobjectAdjustment::MemberPointerAdjustment: 4485 if (!HandleMemberPointerAccess(this->Info, Type, Result, 4486 Adjustments[I].Ptr.RHS)) 4487 return false; 4488 Type = Adjustments[I].Ptr.MPT->getPointeeType(); 4489 break; 4490 } 4491 } 4492 4493 return true; 4494} 4495 4496bool 4497LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { 4498 assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?"); 4499 // Defer visiting the literal until the lvalue-to-rvalue conversion. We can 4500 // only see this when folding in C, so there's no standard to follow here. 4501 return Success(E); 4502} 4503 4504bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) { 4505 if (!E->isPotentiallyEvaluated()) 4506 return Success(E); 4507 4508 Info.Diag(E, diag::note_constexpr_typeid_polymorphic) 4509 << E->getExprOperand()->getType() 4510 << E->getExprOperand()->getSourceRange(); 4511 return false; 4512} 4513 4514bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) { 4515 return Success(E); 4516} 4517 4518bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) { 4519 // Handle static data members. 4520 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) { 4521 VisitIgnoredValue(E->getBase()); 4522 return VisitVarDecl(E, VD); 4523 } 4524 4525 // Handle static member functions. 4526 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) { 4527 if (MD->isStatic()) { 4528 VisitIgnoredValue(E->getBase()); 4529 return Success(MD); 4530 } 4531 } 4532 4533 // Handle non-static data members. 4534 return LValueExprEvaluatorBaseTy::VisitMemberExpr(E); 4535} 4536 4537bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) { 4538 // FIXME: Deal with vectors as array subscript bases. 4539 if (E->getBase()->getType()->isVectorType()) 4540 return Error(E); 4541 4542 if (!EvaluatePointer(E->getBase(), Result, Info)) 4543 return false; 4544 4545 APSInt Index; 4546 if (!EvaluateInteger(E->getIdx(), Index, Info)) 4547 return false; 4548 4549 return HandleLValueArrayAdjustment(Info, E, Result, E->getType(), 4550 getExtValue(Index)); 4551} 4552 4553bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) { 4554 return EvaluatePointer(E->getSubExpr(), Result, Info); 4555} 4556 4557bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 4558 if (!Visit(E->getSubExpr())) 4559 return false; 4560 // __real is a no-op on scalar lvalues. 4561 if (E->getSubExpr()->getType()->isAnyComplexType()) 4562 HandleLValueComplexElement(Info, E, Result, E->getType(), false); 4563 return true; 4564} 4565 4566bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 4567 assert(E->getSubExpr()->getType()->isAnyComplexType() && 4568 "lvalue __imag__ on scalar?"); 4569 if (!Visit(E->getSubExpr())) 4570 return false; 4571 HandleLValueComplexElement(Info, E, Result, E->getType(), true); 4572 return true; 4573} 4574 4575bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) { 4576 if (!Info.getLangOpts().CPlusPlus1y && !Info.keepEvaluatingAfterFailure()) 4577 return Error(UO); 4578 4579 if (!this->Visit(UO->getSubExpr())) 4580 return false; 4581 4582 return handleIncDec( 4583 this->Info, UO, Result, UO->getSubExpr()->getType(), 4584 UO->isIncrementOp(), nullptr); 4585} 4586 4587bool LValueExprEvaluator::VisitCompoundAssignOperator( 4588 const CompoundAssignOperator *CAO) { 4589 if (!Info.getLangOpts().CPlusPlus1y && !Info.keepEvaluatingAfterFailure()) 4590 return Error(CAO); 4591 4592 APValue RHS; 4593 4594 // The overall lvalue result is the result of evaluating the LHS. 4595 if (!this->Visit(CAO->getLHS())) { 4596 if (Info.keepEvaluatingAfterFailure()) 4597 Evaluate(RHS, this->Info, CAO->getRHS()); 4598 return false; 4599 } 4600 4601 if (!Evaluate(RHS, this->Info, CAO->getRHS())) 4602 return false; 4603 4604 return handleCompoundAssignment( 4605 this->Info, CAO, 4606 Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(), 4607 CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS); 4608} 4609 4610bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) { 4611 if (!Info.getLangOpts().CPlusPlus1y && !Info.keepEvaluatingAfterFailure()) 4612 return Error(E); 4613 4614 APValue NewVal; 4615 4616 if (!this->Visit(E->getLHS())) { 4617 if (Info.keepEvaluatingAfterFailure()) 4618 Evaluate(NewVal, this->Info, E->getRHS()); 4619 return false; 4620 } 4621 4622 if (!Evaluate(NewVal, this->Info, E->getRHS())) 4623 return false; 4624 4625 return handleAssignment(this->Info, E, Result, E->getLHS()->getType(), 4626 NewVal); 4627} 4628 4629//===----------------------------------------------------------------------===// 4630// Pointer Evaluation 4631//===----------------------------------------------------------------------===// 4632 4633namespace { 4634class PointerExprEvaluator 4635 : public ExprEvaluatorBase<PointerExprEvaluator> { 4636 LValue &Result; 4637 4638 bool Success(const Expr *E) { 4639 Result.set(E); 4640 return true; 4641 } 4642public: 4643 4644 PointerExprEvaluator(EvalInfo &info, LValue &Result) 4645 : ExprEvaluatorBaseTy(info), Result(Result) {} 4646 4647 bool Success(const APValue &V, const Expr *E) { 4648 Result.setFrom(Info.Ctx, V); 4649 return true; 4650 } 4651 bool ZeroInitialization(const Expr *E) { 4652 return Success((Expr*)nullptr); 4653 } 4654 4655 bool VisitBinaryOperator(const BinaryOperator *E); 4656 bool VisitCastExpr(const CastExpr* E); 4657 bool VisitUnaryAddrOf(const UnaryOperator *E); 4658 bool VisitObjCStringLiteral(const ObjCStringLiteral *E) 4659 { return Success(E); } 4660 bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) 4661 { return Success(E); } 4662 bool VisitAddrLabelExpr(const AddrLabelExpr *E) 4663 { return Success(E); } 4664 bool VisitCallExpr(const CallExpr *E); 4665 bool VisitBlockExpr(const BlockExpr *E) { 4666 if (!E->getBlockDecl()->hasCaptures()) 4667 return Success(E); 4668 return Error(E); 4669 } 4670 bool VisitCXXThisExpr(const CXXThisExpr *E) { 4671 // Can't look at 'this' when checking a potential constant expression. 4672 if (Info.checkingPotentialConstantExpression()) 4673 return false; 4674 if (!Info.CurrentCall->This) { 4675 if (Info.getLangOpts().CPlusPlus11) 4676 Info.Diag(E, diag::note_constexpr_this) << E->isImplicit(); 4677 else 4678 Info.Diag(E); 4679 return false; 4680 } 4681 Result = *Info.CurrentCall->This; 4682 return true; 4683 } 4684 4685 // FIXME: Missing: @protocol, @selector 4686}; 4687} // end anonymous namespace 4688 4689static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info) { 4690 assert(E->isRValue() && E->getType()->hasPointerRepresentation()); 4691 return PointerExprEvaluator(Info, Result).Visit(E); 4692} 4693 4694bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 4695 if (E->getOpcode() != BO_Add && 4696 E->getOpcode() != BO_Sub) 4697 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 4698 4699 const Expr *PExp = E->getLHS(); 4700 const Expr *IExp = E->getRHS(); 4701 if (IExp->getType()->isPointerType()) 4702 std::swap(PExp, IExp); 4703 4704 bool EvalPtrOK = EvaluatePointer(PExp, Result, Info); 4705 if (!EvalPtrOK && !Info.keepEvaluatingAfterFailure()) 4706 return false; 4707 4708 llvm::APSInt Offset; 4709 if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK) 4710 return false; 4711 4712 int64_t AdditionalOffset = getExtValue(Offset); 4713 if (E->getOpcode() == BO_Sub) 4714 AdditionalOffset = -AdditionalOffset; 4715 4716 QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType(); 4717 return HandleLValueArrayAdjustment(Info, E, Result, Pointee, 4718 AdditionalOffset); 4719} 4720 4721bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { 4722 return EvaluateLValue(E->getSubExpr(), Result, Info); 4723} 4724 4725bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) { 4726 const Expr* SubExpr = E->getSubExpr(); 4727 4728 switch (E->getCastKind()) { 4729 default: 4730 break; 4731 4732 case CK_BitCast: 4733 case CK_CPointerToObjCPointerCast: 4734 case CK_BlockPointerToObjCPointerCast: 4735 case CK_AnyPointerToBlockPointerCast: 4736 if (!Visit(SubExpr)) 4737 return false; 4738 // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are 4739 // permitted in constant expressions in C++11. Bitcasts from cv void* are 4740 // also static_casts, but we disallow them as a resolution to DR1312. 4741 if (!E->getType()->isVoidPointerType()) { 4742 Result.Designator.setInvalid(); 4743 if (SubExpr->getType()->isVoidPointerType()) 4744 CCEDiag(E, diag::note_constexpr_invalid_cast) 4745 << 3 << SubExpr->getType(); 4746 else 4747 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 4748 } 4749 return true; 4750 4751 case CK_DerivedToBase: 4752 case CK_UncheckedDerivedToBase: 4753 if (!EvaluatePointer(E->getSubExpr(), Result, Info)) 4754 return false; 4755 if (!Result.Base && Result.Offset.isZero()) 4756 return true; 4757 4758 // Now figure out the necessary offset to add to the base LV to get from 4759 // the derived class to the base class. 4760 return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()-> 4761 castAs<PointerType>()->getPointeeType(), 4762 Result); 4763 4764 case CK_BaseToDerived: 4765 if (!Visit(E->getSubExpr())) 4766 return false; 4767 if (!Result.Base && Result.Offset.isZero()) 4768 return true; 4769 return HandleBaseToDerivedCast(Info, E, Result); 4770 4771 case CK_NullToPointer: 4772 VisitIgnoredValue(E->getSubExpr()); 4773 return ZeroInitialization(E); 4774 4775 case CK_IntegralToPointer: { 4776 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 4777 4778 APValue Value; 4779 if (!EvaluateIntegerOrLValue(SubExpr, Value, Info)) 4780 break; 4781 4782 if (Value.isInt()) { 4783 unsigned Size = Info.Ctx.getTypeSize(E->getType()); 4784 uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue(); 4785 Result.Base = (Expr*)nullptr; 4786 Result.Offset = CharUnits::fromQuantity(N); 4787 Result.CallIndex = 0; 4788 Result.Designator.setInvalid(); 4789 return true; 4790 } else { 4791 // Cast is of an lvalue, no need to change value. 4792 Result.setFrom(Info.Ctx, Value); 4793 return true; 4794 } 4795 } 4796 case CK_ArrayToPointerDecay: 4797 if (SubExpr->isGLValue()) { 4798 if (!EvaluateLValue(SubExpr, Result, Info)) 4799 return false; 4800 } else { 4801 Result.set(SubExpr, Info.CurrentCall->Index); 4802 if (!EvaluateInPlace(Info.CurrentCall->createTemporary(SubExpr, false), 4803 Info, Result, SubExpr)) 4804 return false; 4805 } 4806 // The result is a pointer to the first element of the array. 4807 if (const ConstantArrayType *CAT 4808 = Info.Ctx.getAsConstantArrayType(SubExpr->getType())) 4809 Result.addArray(Info, E, CAT); 4810 else 4811 Result.Designator.setInvalid(); 4812 return true; 4813 4814 case CK_FunctionToPointerDecay: 4815 return EvaluateLValue(SubExpr, Result, Info); 4816 } 4817 4818 return ExprEvaluatorBaseTy::VisitCastExpr(E); 4819} 4820 4821bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) { 4822 if (IsStringLiteralCall(E)) 4823 return Success(E); 4824 4825 switch (E->getBuiltinCallee()) { 4826 case Builtin::BI__builtin_addressof: 4827 return EvaluateLValue(E->getArg(0), Result, Info); 4828 4829 default: 4830 return ExprEvaluatorBaseTy::VisitCallExpr(E); 4831 } 4832} 4833 4834//===----------------------------------------------------------------------===// 4835// Member Pointer Evaluation 4836//===----------------------------------------------------------------------===// 4837 4838namespace { 4839class MemberPointerExprEvaluator 4840 : public ExprEvaluatorBase<MemberPointerExprEvaluator> { 4841 MemberPtr &Result; 4842 4843 bool Success(const ValueDecl *D) { 4844 Result = MemberPtr(D); 4845 return true; 4846 } 4847public: 4848 4849 MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result) 4850 : ExprEvaluatorBaseTy(Info), Result(Result) {} 4851 4852 bool Success(const APValue &V, const Expr *E) { 4853 Result.setFrom(V); 4854 return true; 4855 } 4856 bool ZeroInitialization(const Expr *E) { 4857 return Success((const ValueDecl*)nullptr); 4858 } 4859 4860 bool VisitCastExpr(const CastExpr *E); 4861 bool VisitUnaryAddrOf(const UnaryOperator *E); 4862}; 4863} // end anonymous namespace 4864 4865static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, 4866 EvalInfo &Info) { 4867 assert(E->isRValue() && E->getType()->isMemberPointerType()); 4868 return MemberPointerExprEvaluator(Info, Result).Visit(E); 4869} 4870 4871bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) { 4872 switch (E->getCastKind()) { 4873 default: 4874 return ExprEvaluatorBaseTy::VisitCastExpr(E); 4875 4876 case CK_NullToMemberPointer: 4877 VisitIgnoredValue(E->getSubExpr()); 4878 return ZeroInitialization(E); 4879 4880 case CK_BaseToDerivedMemberPointer: { 4881 if (!Visit(E->getSubExpr())) 4882 return false; 4883 if (E->path_empty()) 4884 return true; 4885 // Base-to-derived member pointer casts store the path in derived-to-base 4886 // order, so iterate backwards. The CXXBaseSpecifier also provides us with 4887 // the wrong end of the derived->base arc, so stagger the path by one class. 4888 typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter; 4889 for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin()); 4890 PathI != PathE; ++PathI) { 4891 assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); 4892 const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl(); 4893 if (!Result.castToDerived(Derived)) 4894 return Error(E); 4895 } 4896 const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass(); 4897 if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl())) 4898 return Error(E); 4899 return true; 4900 } 4901 4902 case CK_DerivedToBaseMemberPointer: 4903 if (!Visit(E->getSubExpr())) 4904 return false; 4905 for (CastExpr::path_const_iterator PathI = E->path_begin(), 4906 PathE = E->path_end(); PathI != PathE; ++PathI) { 4907 assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); 4908 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); 4909 if (!Result.castToBase(Base)) 4910 return Error(E); 4911 } 4912 return true; 4913 } 4914} 4915 4916bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { 4917 // C++11 [expr.unary.op]p3 has very strict rules on how the address of a 4918 // member can be formed. 4919 return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl()); 4920} 4921 4922//===----------------------------------------------------------------------===// 4923// Record Evaluation 4924//===----------------------------------------------------------------------===// 4925 4926namespace { 4927 class RecordExprEvaluator 4928 : public ExprEvaluatorBase<RecordExprEvaluator> { 4929 const LValue &This; 4930 APValue &Result; 4931 public: 4932 4933 RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result) 4934 : ExprEvaluatorBaseTy(info), This(This), Result(Result) {} 4935 4936 bool Success(const APValue &V, const Expr *E) { 4937 Result = V; 4938 return true; 4939 } 4940 bool ZeroInitialization(const Expr *E); 4941 4942 bool VisitCastExpr(const CastExpr *E); 4943 bool VisitInitListExpr(const InitListExpr *E); 4944 bool VisitCXXConstructExpr(const CXXConstructExpr *E); 4945 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E); 4946 }; 4947} 4948 4949/// Perform zero-initialization on an object of non-union class type. 4950/// C++11 [dcl.init]p5: 4951/// To zero-initialize an object or reference of type T means: 4952/// [...] 4953/// -- if T is a (possibly cv-qualified) non-union class type, 4954/// each non-static data member and each base-class subobject is 4955/// zero-initialized 4956static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E, 4957 const RecordDecl *RD, 4958 const LValue &This, APValue &Result) { 4959 assert(!RD->isUnion() && "Expected non-union class type"); 4960 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD); 4961 Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0, 4962 std::distance(RD->field_begin(), RD->field_end())); 4963 4964 if (RD->isInvalidDecl()) return false; 4965 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 4966 4967 if (CD) { 4968 unsigned Index = 0; 4969 for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), 4970 End = CD->bases_end(); I != End; ++I, ++Index) { 4971 const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl(); 4972 LValue Subobject = This; 4973 if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout)) 4974 return false; 4975 if (!HandleClassZeroInitialization(Info, E, Base, Subobject, 4976 Result.getStructBase(Index))) 4977 return false; 4978 } 4979 } 4980 4981 for (const auto *I : RD->fields()) { 4982 // -- if T is a reference type, no initialization is performed. 4983 if (I->getType()->isReferenceType()) 4984 continue; 4985 4986 LValue Subobject = This; 4987 if (!HandleLValueMember(Info, E, Subobject, I, &Layout)) 4988 return false; 4989 4990 ImplicitValueInitExpr VIE(I->getType()); 4991 if (!EvaluateInPlace( 4992 Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE)) 4993 return false; 4994 } 4995 4996 return true; 4997} 4998 4999bool RecordExprEvaluator::ZeroInitialization(const Expr *E) { 5000 const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl(); 5001 if (RD->isInvalidDecl()) return false; 5002 if (RD->isUnion()) { 5003 // C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the 5004 // object's first non-static named data member is zero-initialized 5005 RecordDecl::field_iterator I = RD->field_begin(); 5006 if (I == RD->field_end()) { 5007 Result = APValue((const FieldDecl*)nullptr); 5008 return true; 5009 } 5010 5011 LValue Subobject = This; 5012 if (!HandleLValueMember(Info, E, Subobject, *I)) 5013 return false; 5014 Result = APValue(*I); 5015 ImplicitValueInitExpr VIE(I->getType()); 5016 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE); 5017 } 5018 5019 if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) { 5020 Info.Diag(E, diag::note_constexpr_virtual_base) << RD; 5021 return false; 5022 } 5023 5024 return HandleClassZeroInitialization(Info, E, RD, This, Result); 5025} 5026 5027bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) { 5028 switch (E->getCastKind()) { 5029 default: 5030 return ExprEvaluatorBaseTy::VisitCastExpr(E); 5031 5032 case CK_ConstructorConversion: 5033 return Visit(E->getSubExpr()); 5034 5035 case CK_DerivedToBase: 5036 case CK_UncheckedDerivedToBase: { 5037 APValue DerivedObject; 5038 if (!Evaluate(DerivedObject, Info, E->getSubExpr())) 5039 return false; 5040 if (!DerivedObject.isStruct()) 5041 return Error(E->getSubExpr()); 5042 5043 // Derived-to-base rvalue conversion: just slice off the derived part. 5044 APValue *Value = &DerivedObject; 5045 const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl(); 5046 for (CastExpr::path_const_iterator PathI = E->path_begin(), 5047 PathE = E->path_end(); PathI != PathE; ++PathI) { 5048 assert(!(*PathI)->isVirtual() && "record rvalue with virtual base"); 5049 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); 5050 Value = &Value->getStructBase(getBaseIndex(RD, Base)); 5051 RD = Base; 5052 } 5053 Result = *Value; 5054 return true; 5055 } 5056 } 5057} 5058 5059bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 5060 const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl(); 5061 if (RD->isInvalidDecl()) return false; 5062 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 5063 5064 if (RD->isUnion()) { 5065 const FieldDecl *Field = E->getInitializedFieldInUnion(); 5066 Result = APValue(Field); 5067 if (!Field) 5068 return true; 5069 5070 // If the initializer list for a union does not contain any elements, the 5071 // first element of the union is value-initialized. 5072 // FIXME: The element should be initialized from an initializer list. 5073 // Is this difference ever observable for initializer lists which 5074 // we don't build? 5075 ImplicitValueInitExpr VIE(Field->getType()); 5076 const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE; 5077 5078 LValue Subobject = This; 5079 if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout)) 5080 return false; 5081 5082 // Temporarily override This, in case there's a CXXDefaultInitExpr in here. 5083 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, 5084 isa<CXXDefaultInitExpr>(InitExpr)); 5085 5086 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr); 5087 } 5088 5089 assert((!isa<CXXRecordDecl>(RD) || !cast<CXXRecordDecl>(RD)->getNumBases()) && 5090 "initializer list for class with base classes"); 5091 Result = APValue(APValue::UninitStruct(), 0, 5092 std::distance(RD->field_begin(), RD->field_end())); 5093 unsigned ElementNo = 0; 5094 bool Success = true; 5095 for (const auto *Field : RD->fields()) { 5096 // Anonymous bit-fields are not considered members of the class for 5097 // purposes of aggregate initialization. 5098 if (Field->isUnnamedBitfield()) 5099 continue; 5100 5101 LValue Subobject = This; 5102 5103 bool HaveInit = ElementNo < E->getNumInits(); 5104 5105 // FIXME: Diagnostics here should point to the end of the initializer 5106 // list, not the start. 5107 if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E, 5108 Subobject, Field, &Layout)) 5109 return false; 5110 5111 // Perform an implicit value-initialization for members beyond the end of 5112 // the initializer list. 5113 ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType()); 5114 const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE; 5115 5116 // Temporarily override This, in case there's a CXXDefaultInitExpr in here. 5117 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, 5118 isa<CXXDefaultInitExpr>(Init)); 5119 5120 APValue &FieldVal = Result.getStructField(Field->getFieldIndex()); 5121 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) || 5122 (Field->isBitField() && !truncateBitfieldValue(Info, Init, 5123 FieldVal, Field))) { 5124 if (!Info.keepEvaluatingAfterFailure()) 5125 return false; 5126 Success = false; 5127 } 5128 } 5129 5130 return Success; 5131} 5132 5133bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { 5134 const CXXConstructorDecl *FD = E->getConstructor(); 5135 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false; 5136 5137 bool ZeroInit = E->requiresZeroInitialization(); 5138 if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { 5139 // If we've already performed zero-initialization, we're already done. 5140 if (!Result.isUninit()) 5141 return true; 5142 5143 // We can get here in two different ways: 5144 // 1) We're performing value-initialization, and should zero-initialize 5145 // the object, or 5146 // 2) We're performing default-initialization of an object with a trivial 5147 // constexpr default constructor, in which case we should start the 5148 // lifetimes of all the base subobjects (there can be no data member 5149 // subobjects in this case) per [basic.life]p1. 5150 // Either way, ZeroInitialization is appropriate. 5151 return ZeroInitialization(E); 5152 } 5153 5154 const FunctionDecl *Definition = nullptr; 5155 FD->getBody(Definition); 5156 5157 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition)) 5158 return false; 5159 5160 // Avoid materializing a temporary for an elidable copy/move constructor. 5161 if (E->isElidable() && !ZeroInit) 5162 if (const MaterializeTemporaryExpr *ME 5163 = dyn_cast<MaterializeTemporaryExpr>(E->getArg(0))) 5164 return Visit(ME->GetTemporaryExpr()); 5165 5166 if (ZeroInit && !ZeroInitialization(E)) 5167 return false; 5168 5169 ArrayRef<const Expr *> Args(E->getArgs(), E->getNumArgs()); 5170 return HandleConstructorCall(E->getExprLoc(), This, Args, 5171 cast<CXXConstructorDecl>(Definition), Info, 5172 Result); 5173} 5174 5175bool RecordExprEvaluator::VisitCXXStdInitializerListExpr( 5176 const CXXStdInitializerListExpr *E) { 5177 const ConstantArrayType *ArrayType = 5178 Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType()); 5179 5180 LValue Array; 5181 if (!EvaluateLValue(E->getSubExpr(), Array, Info)) 5182 return false; 5183 5184 // Get a pointer to the first element of the array. 5185 Array.addArray(Info, E, ArrayType); 5186 5187 // FIXME: Perform the checks on the field types in SemaInit. 5188 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl(); 5189 RecordDecl::field_iterator Field = Record->field_begin(); 5190 if (Field == Record->field_end()) 5191 return Error(E); 5192 5193 // Start pointer. 5194 if (!Field->getType()->isPointerType() || 5195 !Info.Ctx.hasSameType(Field->getType()->getPointeeType(), 5196 ArrayType->getElementType())) 5197 return Error(E); 5198 5199 // FIXME: What if the initializer_list type has base classes, etc? 5200 Result = APValue(APValue::UninitStruct(), 0, 2); 5201 Array.moveInto(Result.getStructField(0)); 5202 5203 if (++Field == Record->field_end()) 5204 return Error(E); 5205 5206 if (Field->getType()->isPointerType() && 5207 Info.Ctx.hasSameType(Field->getType()->getPointeeType(), 5208 ArrayType->getElementType())) { 5209 // End pointer. 5210 if (!HandleLValueArrayAdjustment(Info, E, Array, 5211 ArrayType->getElementType(), 5212 ArrayType->getSize().getZExtValue())) 5213 return false; 5214 Array.moveInto(Result.getStructField(1)); 5215 } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType())) 5216 // Length. 5217 Result.getStructField(1) = APValue(APSInt(ArrayType->getSize())); 5218 else 5219 return Error(E); 5220 5221 if (++Field != Record->field_end()) 5222 return Error(E); 5223 5224 return true; 5225} 5226 5227static bool EvaluateRecord(const Expr *E, const LValue &This, 5228 APValue &Result, EvalInfo &Info) { 5229 assert(E->isRValue() && E->getType()->isRecordType() && 5230 "can't evaluate expression as a record rvalue"); 5231 return RecordExprEvaluator(Info, This, Result).Visit(E); 5232} 5233 5234//===----------------------------------------------------------------------===// 5235// Temporary Evaluation 5236// 5237// Temporaries are represented in the AST as rvalues, but generally behave like 5238// lvalues. The full-object of which the temporary is a subobject is implicitly 5239// materialized so that a reference can bind to it. 5240//===----------------------------------------------------------------------===// 5241namespace { 5242class TemporaryExprEvaluator 5243 : public LValueExprEvaluatorBase<TemporaryExprEvaluator> { 5244public: 5245 TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) : 5246 LValueExprEvaluatorBaseTy(Info, Result) {} 5247 5248 /// Visit an expression which constructs the value of this temporary. 5249 bool VisitConstructExpr(const Expr *E) { 5250 Result.set(E, Info.CurrentCall->Index); 5251 return EvaluateInPlace(Info.CurrentCall->createTemporary(E, false), 5252 Info, Result, E); 5253 } 5254 5255 bool VisitCastExpr(const CastExpr *E) { 5256 switch (E->getCastKind()) { 5257 default: 5258 return LValueExprEvaluatorBaseTy::VisitCastExpr(E); 5259 5260 case CK_ConstructorConversion: 5261 return VisitConstructExpr(E->getSubExpr()); 5262 } 5263 } 5264 bool VisitInitListExpr(const InitListExpr *E) { 5265 return VisitConstructExpr(E); 5266 } 5267 bool VisitCXXConstructExpr(const CXXConstructExpr *E) { 5268 return VisitConstructExpr(E); 5269 } 5270 bool VisitCallExpr(const CallExpr *E) { 5271 return VisitConstructExpr(E); 5272 } 5273}; 5274} // end anonymous namespace 5275 5276/// Evaluate an expression of record type as a temporary. 5277static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) { 5278 assert(E->isRValue() && E->getType()->isRecordType()); 5279 return TemporaryExprEvaluator(Info, Result).Visit(E); 5280} 5281 5282//===----------------------------------------------------------------------===// 5283// Vector Evaluation 5284//===----------------------------------------------------------------------===// 5285 5286namespace { 5287 class VectorExprEvaluator 5288 : public ExprEvaluatorBase<VectorExprEvaluator> { 5289 APValue &Result; 5290 public: 5291 5292 VectorExprEvaluator(EvalInfo &info, APValue &Result) 5293 : ExprEvaluatorBaseTy(info), Result(Result) {} 5294 5295 bool Success(const ArrayRef<APValue> &V, const Expr *E) { 5296 assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements()); 5297 // FIXME: remove this APValue copy. 5298 Result = APValue(V.data(), V.size()); 5299 return true; 5300 } 5301 bool Success(const APValue &V, const Expr *E) { 5302 assert(V.isVector()); 5303 Result = V; 5304 return true; 5305 } 5306 bool ZeroInitialization(const Expr *E); 5307 5308 bool VisitUnaryReal(const UnaryOperator *E) 5309 { return Visit(E->getSubExpr()); } 5310 bool VisitCastExpr(const CastExpr* E); 5311 bool VisitInitListExpr(const InitListExpr *E); 5312 bool VisitUnaryImag(const UnaryOperator *E); 5313 // FIXME: Missing: unary -, unary ~, binary add/sub/mul/div, 5314 // binary comparisons, binary and/or/xor, 5315 // shufflevector, ExtVectorElementExpr 5316 }; 5317} // end anonymous namespace 5318 5319static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) { 5320 assert(E->isRValue() && E->getType()->isVectorType() &&"not a vector rvalue"); 5321 return VectorExprEvaluator(Info, Result).Visit(E); 5322} 5323 5324bool VectorExprEvaluator::VisitCastExpr(const CastExpr* E) { 5325 const VectorType *VTy = E->getType()->castAs<VectorType>(); 5326 unsigned NElts = VTy->getNumElements(); 5327 5328 const Expr *SE = E->getSubExpr(); 5329 QualType SETy = SE->getType(); 5330 5331 switch (E->getCastKind()) { 5332 case CK_VectorSplat: { 5333 APValue Val = APValue(); 5334 if (SETy->isIntegerType()) { 5335 APSInt IntResult; 5336 if (!EvaluateInteger(SE, IntResult, Info)) 5337 return false; 5338 Val = APValue(IntResult); 5339 } else if (SETy->isRealFloatingType()) { 5340 APFloat F(0.0); 5341 if (!EvaluateFloat(SE, F, Info)) 5342 return false; 5343 Val = APValue(F); 5344 } else { 5345 return Error(E); 5346 } 5347 5348 // Splat and create vector APValue. 5349 SmallVector<APValue, 4> Elts(NElts, Val); 5350 return Success(Elts, E); 5351 } 5352 case CK_BitCast: { 5353 // Evaluate the operand into an APInt we can extract from. 5354 llvm::APInt SValInt; 5355 if (!EvalAndBitcastToAPInt(Info, SE, SValInt)) 5356 return false; 5357 // Extract the elements 5358 QualType EltTy = VTy->getElementType(); 5359 unsigned EltSize = Info.Ctx.getTypeSize(EltTy); 5360 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); 5361 SmallVector<APValue, 4> Elts; 5362 if (EltTy->isRealFloatingType()) { 5363 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy); 5364 unsigned FloatEltSize = EltSize; 5365 if (&Sem == &APFloat::x87DoubleExtended) 5366 FloatEltSize = 80; 5367 for (unsigned i = 0; i < NElts; i++) { 5368 llvm::APInt Elt; 5369 if (BigEndian) 5370 Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize); 5371 else 5372 Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize); 5373 Elts.push_back(APValue(APFloat(Sem, Elt))); 5374 } 5375 } else if (EltTy->isIntegerType()) { 5376 for (unsigned i = 0; i < NElts; i++) { 5377 llvm::APInt Elt; 5378 if (BigEndian) 5379 Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize); 5380 else 5381 Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize); 5382 Elts.push_back(APValue(APSInt(Elt, EltTy->isSignedIntegerType()))); 5383 } 5384 } else { 5385 return Error(E); 5386 } 5387 return Success(Elts, E); 5388 } 5389 default: 5390 return ExprEvaluatorBaseTy::VisitCastExpr(E); 5391 } 5392} 5393 5394bool 5395VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 5396 const VectorType *VT = E->getType()->castAs<VectorType>(); 5397 unsigned NumInits = E->getNumInits(); 5398 unsigned NumElements = VT->getNumElements(); 5399 5400 QualType EltTy = VT->getElementType(); 5401 SmallVector<APValue, 4> Elements; 5402 5403 // The number of initializers can be less than the number of 5404 // vector elements. For OpenCL, this can be due to nested vector 5405 // initialization. For GCC compatibility, missing trailing elements 5406 // should be initialized with zeroes. 5407 unsigned CountInits = 0, CountElts = 0; 5408 while (CountElts < NumElements) { 5409 // Handle nested vector initialization. 5410 if (CountInits < NumInits 5411 && E->getInit(CountInits)->getType()->isVectorType()) { 5412 APValue v; 5413 if (!EvaluateVector(E->getInit(CountInits), v, Info)) 5414 return Error(E); 5415 unsigned vlen = v.getVectorLength(); 5416 for (unsigned j = 0; j < vlen; j++) 5417 Elements.push_back(v.getVectorElt(j)); 5418 CountElts += vlen; 5419 } else if (EltTy->isIntegerType()) { 5420 llvm::APSInt sInt(32); 5421 if (CountInits < NumInits) { 5422 if (!EvaluateInteger(E->getInit(CountInits), sInt, Info)) 5423 return false; 5424 } else // trailing integer zero. 5425 sInt = Info.Ctx.MakeIntValue(0, EltTy); 5426 Elements.push_back(APValue(sInt)); 5427 CountElts++; 5428 } else { 5429 llvm::APFloat f(0.0); 5430 if (CountInits < NumInits) { 5431 if (!EvaluateFloat(E->getInit(CountInits), f, Info)) 5432 return false; 5433 } else // trailing float zero. 5434 f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)); 5435 Elements.push_back(APValue(f)); 5436 CountElts++; 5437 } 5438 CountInits++; 5439 } 5440 return Success(Elements, E); 5441} 5442 5443bool 5444VectorExprEvaluator::ZeroInitialization(const Expr *E) { 5445 const VectorType *VT = E->getType()->getAs<VectorType>(); 5446 QualType EltTy = VT->getElementType(); 5447 APValue ZeroElement; 5448 if (EltTy->isIntegerType()) 5449 ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy)); 5450 else 5451 ZeroElement = 5452 APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy))); 5453 5454 SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement); 5455 return Success(Elements, E); 5456} 5457 5458bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 5459 VisitIgnoredValue(E->getSubExpr()); 5460 return ZeroInitialization(E); 5461} 5462 5463//===----------------------------------------------------------------------===// 5464// Array Evaluation 5465//===----------------------------------------------------------------------===// 5466 5467namespace { 5468 class ArrayExprEvaluator 5469 : public ExprEvaluatorBase<ArrayExprEvaluator> { 5470 const LValue &This; 5471 APValue &Result; 5472 public: 5473 5474 ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result) 5475 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {} 5476 5477 bool Success(const APValue &V, const Expr *E) { 5478 assert((V.isArray() || V.isLValue()) && 5479 "expected array or string literal"); 5480 Result = V; 5481 return true; 5482 } 5483 5484 bool ZeroInitialization(const Expr *E) { 5485 const ConstantArrayType *CAT = 5486 Info.Ctx.getAsConstantArrayType(E->getType()); 5487 if (!CAT) 5488 return Error(E); 5489 5490 Result = APValue(APValue::UninitArray(), 0, 5491 CAT->getSize().getZExtValue()); 5492 if (!Result.hasArrayFiller()) return true; 5493 5494 // Zero-initialize all elements. 5495 LValue Subobject = This; 5496 Subobject.addArray(Info, E, CAT); 5497 ImplicitValueInitExpr VIE(CAT->getElementType()); 5498 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE); 5499 } 5500 5501 bool VisitInitListExpr(const InitListExpr *E); 5502 bool VisitCXXConstructExpr(const CXXConstructExpr *E); 5503 bool VisitCXXConstructExpr(const CXXConstructExpr *E, 5504 const LValue &Subobject, 5505 APValue *Value, QualType Type); 5506 }; 5507} // end anonymous namespace 5508 5509static bool EvaluateArray(const Expr *E, const LValue &This, 5510 APValue &Result, EvalInfo &Info) { 5511 assert(E->isRValue() && E->getType()->isArrayType() && "not an array rvalue"); 5512 return ArrayExprEvaluator(Info, This, Result).Visit(E); 5513} 5514 5515bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 5516 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(E->getType()); 5517 if (!CAT) 5518 return Error(E); 5519 5520 // C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...] 5521 // an appropriately-typed string literal enclosed in braces. 5522 if (E->isStringLiteralInit()) { 5523 LValue LV; 5524 if (!EvaluateLValue(E->getInit(0), LV, Info)) 5525 return false; 5526 APValue Val; 5527 LV.moveInto(Val); 5528 return Success(Val, E); 5529 } 5530 5531 bool Success = true; 5532 5533 assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) && 5534 "zero-initialized array shouldn't have any initialized elts"); 5535 APValue Filler; 5536 if (Result.isArray() && Result.hasArrayFiller()) 5537 Filler = Result.getArrayFiller(); 5538 5539 unsigned NumEltsToInit = E->getNumInits(); 5540 unsigned NumElts = CAT->getSize().getZExtValue(); 5541 const Expr *FillerExpr = E->hasArrayFiller() ? E->getArrayFiller() : nullptr; 5542 5543 // If the initializer might depend on the array index, run it for each 5544 // array element. For now, just whitelist non-class value-initialization. 5545 if (NumEltsToInit != NumElts && !isa<ImplicitValueInitExpr>(FillerExpr)) 5546 NumEltsToInit = NumElts; 5547 5548 Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts); 5549 5550 // If the array was previously zero-initialized, preserve the 5551 // zero-initialized values. 5552 if (!Filler.isUninit()) { 5553 for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I) 5554 Result.getArrayInitializedElt(I) = Filler; 5555 if (Result.hasArrayFiller()) 5556 Result.getArrayFiller() = Filler; 5557 } 5558 5559 LValue Subobject = This; 5560 Subobject.addArray(Info, E, CAT); 5561 for (unsigned Index = 0; Index != NumEltsToInit; ++Index) { 5562 const Expr *Init = 5563 Index < E->getNumInits() ? E->getInit(Index) : FillerExpr; 5564 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), 5565 Info, Subobject, Init) || 5566 !HandleLValueArrayAdjustment(Info, Init, Subobject, 5567 CAT->getElementType(), 1)) { 5568 if (!Info.keepEvaluatingAfterFailure()) 5569 return false; 5570 Success = false; 5571 } 5572 } 5573 5574 if (!Result.hasArrayFiller()) 5575 return Success; 5576 5577 // If we get here, we have a trivial filler, which we can just evaluate 5578 // once and splat over the rest of the array elements. 5579 assert(FillerExpr && "no array filler for incomplete init list"); 5580 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, 5581 FillerExpr) && Success; 5582} 5583 5584bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { 5585 return VisitCXXConstructExpr(E, This, &Result, E->getType()); 5586} 5587 5588bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E, 5589 const LValue &Subobject, 5590 APValue *Value, 5591 QualType Type) { 5592 bool HadZeroInit = !Value->isUninit(); 5593 5594 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) { 5595 unsigned N = CAT->getSize().getZExtValue(); 5596 5597 // Preserve the array filler if we had prior zero-initialization. 5598 APValue Filler = 5599 HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller() 5600 : APValue(); 5601 5602 *Value = APValue(APValue::UninitArray(), N, N); 5603 5604 if (HadZeroInit) 5605 for (unsigned I = 0; I != N; ++I) 5606 Value->getArrayInitializedElt(I) = Filler; 5607 5608 // Initialize the elements. 5609 LValue ArrayElt = Subobject; 5610 ArrayElt.addArray(Info, E, CAT); 5611 for (unsigned I = 0; I != N; ++I) 5612 if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I), 5613 CAT->getElementType()) || 5614 !HandleLValueArrayAdjustment(Info, E, ArrayElt, 5615 CAT->getElementType(), 1)) 5616 return false; 5617 5618 return true; 5619 } 5620 5621 if (!Type->isRecordType()) 5622 return Error(E); 5623 5624 const CXXConstructorDecl *FD = E->getConstructor(); 5625 5626 bool ZeroInit = E->requiresZeroInitialization(); 5627 if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { 5628 if (HadZeroInit) 5629 return true; 5630 5631 // See RecordExprEvaluator::VisitCXXConstructExpr for explanation. 5632 ImplicitValueInitExpr VIE(Type); 5633 return EvaluateInPlace(*Value, Info, Subobject, &VIE); 5634 } 5635 5636 const FunctionDecl *Definition = nullptr; 5637 FD->getBody(Definition); 5638 5639 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition)) 5640 return false; 5641 5642 if (ZeroInit && !HadZeroInit) { 5643 ImplicitValueInitExpr VIE(Type); 5644 if (!EvaluateInPlace(*Value, Info, Subobject, &VIE)) 5645 return false; 5646 } 5647 5648 ArrayRef<const Expr *> Args(E->getArgs(), E->getNumArgs()); 5649 return HandleConstructorCall(E->getExprLoc(), Subobject, Args, 5650 cast<CXXConstructorDecl>(Definition), 5651 Info, *Value); 5652} 5653 5654//===----------------------------------------------------------------------===// 5655// Integer Evaluation 5656// 5657// As a GNU extension, we support casting pointers to sufficiently-wide integer 5658// types and back in constant folding. Integer values are thus represented 5659// either as an integer-valued APValue, or as an lvalue-valued APValue. 5660//===----------------------------------------------------------------------===// 5661 5662namespace { 5663class IntExprEvaluator 5664 : public ExprEvaluatorBase<IntExprEvaluator> { 5665 APValue &Result; 5666public: 5667 IntExprEvaluator(EvalInfo &info, APValue &result) 5668 : ExprEvaluatorBaseTy(info), Result(result) {} 5669 5670 bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) { 5671 assert(E->getType()->isIntegralOrEnumerationType() && 5672 "Invalid evaluation result."); 5673 assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() && 5674 "Invalid evaluation result."); 5675 assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && 5676 "Invalid evaluation result."); 5677 Result = APValue(SI); 5678 return true; 5679 } 5680 bool Success(const llvm::APSInt &SI, const Expr *E) { 5681 return Success(SI, E, Result); 5682 } 5683 5684 bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) { 5685 assert(E->getType()->isIntegralOrEnumerationType() && 5686 "Invalid evaluation result."); 5687 assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && 5688 "Invalid evaluation result."); 5689 Result = APValue(APSInt(I)); 5690 Result.getInt().setIsUnsigned( 5691 E->getType()->isUnsignedIntegerOrEnumerationType()); 5692 return true; 5693 } 5694 bool Success(const llvm::APInt &I, const Expr *E) { 5695 return Success(I, E, Result); 5696 } 5697 5698 bool Success(uint64_t Value, const Expr *E, APValue &Result) { 5699 assert(E->getType()->isIntegralOrEnumerationType() && 5700 "Invalid evaluation result."); 5701 Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType())); 5702 return true; 5703 } 5704 bool Success(uint64_t Value, const Expr *E) { 5705 return Success(Value, E, Result); 5706 } 5707 5708 bool Success(CharUnits Size, const Expr *E) { 5709 return Success(Size.getQuantity(), E); 5710 } 5711 5712 bool Success(const APValue &V, const Expr *E) { 5713 if (V.isLValue() || V.isAddrLabelDiff()) { 5714 Result = V; 5715 return true; 5716 } 5717 return Success(V.getInt(), E); 5718 } 5719 5720 bool ZeroInitialization(const Expr *E) { return Success(0, E); } 5721 5722 //===--------------------------------------------------------------------===// 5723 // Visitor Methods 5724 //===--------------------------------------------------------------------===// 5725 5726 bool VisitIntegerLiteral(const IntegerLiteral *E) { 5727 return Success(E->getValue(), E); 5728 } 5729 bool VisitCharacterLiteral(const CharacterLiteral *E) { 5730 return Success(E->getValue(), E); 5731 } 5732 5733 bool CheckReferencedDecl(const Expr *E, const Decl *D); 5734 bool VisitDeclRefExpr(const DeclRefExpr *E) { 5735 if (CheckReferencedDecl(E, E->getDecl())) 5736 return true; 5737 5738 return ExprEvaluatorBaseTy::VisitDeclRefExpr(E); 5739 } 5740 bool VisitMemberExpr(const MemberExpr *E) { 5741 if (CheckReferencedDecl(E, E->getMemberDecl())) { 5742 VisitIgnoredValue(E->getBase()); 5743 return true; 5744 } 5745 5746 return ExprEvaluatorBaseTy::VisitMemberExpr(E); 5747 } 5748 5749 bool VisitCallExpr(const CallExpr *E); 5750 bool VisitBinaryOperator(const BinaryOperator *E); 5751 bool VisitOffsetOfExpr(const OffsetOfExpr *E); 5752 bool VisitUnaryOperator(const UnaryOperator *E); 5753 5754 bool VisitCastExpr(const CastExpr* E); 5755 bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E); 5756 5757 bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) { 5758 return Success(E->getValue(), E); 5759 } 5760 5761 bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) { 5762 return Success(E->getValue(), E); 5763 } 5764 5765 // Note, GNU defines __null as an integer, not a pointer. 5766 bool VisitGNUNullExpr(const GNUNullExpr *E) { 5767 return ZeroInitialization(E); 5768 } 5769 5770 bool VisitTypeTraitExpr(const TypeTraitExpr *E) { 5771 return Success(E->getValue(), E); 5772 } 5773 5774 bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) { 5775 return Success(E->getValue(), E); 5776 } 5777 5778 bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) { 5779 return Success(E->getValue(), E); 5780 } 5781 5782 bool VisitUnaryReal(const UnaryOperator *E); 5783 bool VisitUnaryImag(const UnaryOperator *E); 5784 5785 bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E); 5786 bool VisitSizeOfPackExpr(const SizeOfPackExpr *E); 5787 5788private: 5789 CharUnits GetAlignOfExpr(const Expr *E); 5790 CharUnits GetAlignOfType(QualType T); 5791 static QualType GetObjectType(APValue::LValueBase B); 5792 bool TryEvaluateBuiltinObjectSize(const CallExpr *E); 5793 // FIXME: Missing: array subscript of vector, member of vector 5794}; 5795} // end anonymous namespace 5796 5797/// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and 5798/// produce either the integer value or a pointer. 5799/// 5800/// GCC has a heinous extension which folds casts between pointer types and 5801/// pointer-sized integral types. We support this by allowing the evaluation of 5802/// an integer rvalue to produce a pointer (represented as an lvalue) instead. 5803/// Some simple arithmetic on such values is supported (they are treated much 5804/// like char*). 5805static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, 5806 EvalInfo &Info) { 5807 assert(E->isRValue() && E->getType()->isIntegralOrEnumerationType()); 5808 return IntExprEvaluator(Info, Result).Visit(E); 5809} 5810 5811static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) { 5812 APValue Val; 5813 if (!EvaluateIntegerOrLValue(E, Val, Info)) 5814 return false; 5815 if (!Val.isInt()) { 5816 // FIXME: It would be better to produce the diagnostic for casting 5817 // a pointer to an integer. 5818 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 5819 return false; 5820 } 5821 Result = Val.getInt(); 5822 return true; 5823} 5824 5825/// Check whether the given declaration can be directly converted to an integral 5826/// rvalue. If not, no diagnostic is produced; there are other things we can 5827/// try. 5828bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) { 5829 // Enums are integer constant exprs. 5830 if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) { 5831 // Check for signedness/width mismatches between E type and ECD value. 5832 bool SameSign = (ECD->getInitVal().isSigned() 5833 == E->getType()->isSignedIntegerOrEnumerationType()); 5834 bool SameWidth = (ECD->getInitVal().getBitWidth() 5835 == Info.Ctx.getIntWidth(E->getType())); 5836 if (SameSign && SameWidth) 5837 return Success(ECD->getInitVal(), E); 5838 else { 5839 // Get rid of mismatch (otherwise Success assertions will fail) 5840 // by computing a new value matching the type of E. 5841 llvm::APSInt Val = ECD->getInitVal(); 5842 if (!SameSign) 5843 Val.setIsSigned(!ECD->getInitVal().isSigned()); 5844 if (!SameWidth) 5845 Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType())); 5846 return Success(Val, E); 5847 } 5848 } 5849 return false; 5850} 5851 5852/// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way 5853/// as GCC. 5854static int EvaluateBuiltinClassifyType(const CallExpr *E) { 5855 // The following enum mimics the values returned by GCC. 5856 // FIXME: Does GCC differ between lvalue and rvalue references here? 5857 enum gcc_type_class { 5858 no_type_class = -1, 5859 void_type_class, integer_type_class, char_type_class, 5860 enumeral_type_class, boolean_type_class, 5861 pointer_type_class, reference_type_class, offset_type_class, 5862 real_type_class, complex_type_class, 5863 function_type_class, method_type_class, 5864 record_type_class, union_type_class, 5865 array_type_class, string_type_class, 5866 lang_type_class 5867 }; 5868 5869 // If no argument was supplied, default to "no_type_class". This isn't 5870 // ideal, however it is what gcc does. 5871 if (E->getNumArgs() == 0) 5872 return no_type_class; 5873 5874 QualType ArgTy = E->getArg(0)->getType(); 5875 if (ArgTy->isVoidType()) 5876 return void_type_class; 5877 else if (ArgTy->isEnumeralType()) 5878 return enumeral_type_class; 5879 else if (ArgTy->isBooleanType()) 5880 return boolean_type_class; 5881 else if (ArgTy->isCharType()) 5882 return string_type_class; // gcc doesn't appear to use char_type_class 5883 else if (ArgTy->isIntegerType()) 5884 return integer_type_class; 5885 else if (ArgTy->isPointerType()) 5886 return pointer_type_class; 5887 else if (ArgTy->isReferenceType()) 5888 return reference_type_class; 5889 else if (ArgTy->isRealType()) 5890 return real_type_class; 5891 else if (ArgTy->isComplexType()) 5892 return complex_type_class; 5893 else if (ArgTy->isFunctionType()) 5894 return function_type_class; 5895 else if (ArgTy->isStructureOrClassType()) 5896 return record_type_class; 5897 else if (ArgTy->isUnionType()) 5898 return union_type_class; 5899 else if (ArgTy->isArrayType()) 5900 return array_type_class; 5901 else if (ArgTy->isUnionType()) 5902 return union_type_class; 5903 else // FIXME: offset_type_class, method_type_class, & lang_type_class? 5904 llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type"); 5905} 5906 5907/// EvaluateBuiltinConstantPForLValue - Determine the result of 5908/// __builtin_constant_p when applied to the given lvalue. 5909/// 5910/// An lvalue is only "constant" if it is a pointer or reference to the first 5911/// character of a string literal. 5912template<typename LValue> 5913static bool EvaluateBuiltinConstantPForLValue(const LValue &LV) { 5914 const Expr *E = LV.getLValueBase().template dyn_cast<const Expr*>(); 5915 return E && isa<StringLiteral>(E) && LV.getLValueOffset().isZero(); 5916} 5917 5918/// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to 5919/// GCC as we can manage. 5920static bool EvaluateBuiltinConstantP(ASTContext &Ctx, const Expr *Arg) { 5921 QualType ArgType = Arg->getType(); 5922 5923 // __builtin_constant_p always has one operand. The rules which gcc follows 5924 // are not precisely documented, but are as follows: 5925 // 5926 // - If the operand is of integral, floating, complex or enumeration type, 5927 // and can be folded to a known value of that type, it returns 1. 5928 // - If the operand and can be folded to a pointer to the first character 5929 // of a string literal (or such a pointer cast to an integral type), it 5930 // returns 1. 5931 // 5932 // Otherwise, it returns 0. 5933 // 5934 // FIXME: GCC also intends to return 1 for literals of aggregate types, but 5935 // its support for this does not currently work. 5936 if (ArgType->isIntegralOrEnumerationType()) { 5937 Expr::EvalResult Result; 5938 if (!Arg->EvaluateAsRValue(Result, Ctx) || Result.HasSideEffects) 5939 return false; 5940 5941 APValue &V = Result.Val; 5942 if (V.getKind() == APValue::Int) 5943 return true; 5944 5945 return EvaluateBuiltinConstantPForLValue(V); 5946 } else if (ArgType->isFloatingType() || ArgType->isAnyComplexType()) { 5947 return Arg->isEvaluatable(Ctx); 5948 } else if (ArgType->isPointerType() || Arg->isGLValue()) { 5949 LValue LV; 5950 Expr::EvalStatus Status; 5951 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold); 5952 if ((Arg->isGLValue() ? EvaluateLValue(Arg, LV, Info) 5953 : EvaluatePointer(Arg, LV, Info)) && 5954 !Status.HasSideEffects) 5955 return EvaluateBuiltinConstantPForLValue(LV); 5956 } 5957 5958 // Anything else isn't considered to be sufficiently constant. 5959 return false; 5960} 5961 5962/// Retrieves the "underlying object type" of the given expression, 5963/// as used by __builtin_object_size. 5964QualType IntExprEvaluator::GetObjectType(APValue::LValueBase B) { 5965 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { 5966 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 5967 return VD->getType(); 5968 } else if (const Expr *E = B.get<const Expr*>()) { 5969 if (isa<CompoundLiteralExpr>(E)) 5970 return E->getType(); 5971 } 5972 5973 return QualType(); 5974} 5975 5976bool IntExprEvaluator::TryEvaluateBuiltinObjectSize(const CallExpr *E) { 5977 LValue Base; 5978 5979 { 5980 // The operand of __builtin_object_size is never evaluated for side-effects. 5981 // If there are any, but we can determine the pointed-to object anyway, then 5982 // ignore the side-effects. 5983 SpeculativeEvaluationRAII SpeculativeEval(Info); 5984 if (!EvaluatePointer(E->getArg(0), Base, Info)) 5985 return false; 5986 } 5987 5988 // If we can prove the base is null, lower to zero now. 5989 if (!Base.getLValueBase()) return Success(0, E); 5990 5991 QualType T = GetObjectType(Base.getLValueBase()); 5992 if (T.isNull() || 5993 T->isIncompleteType() || 5994 T->isFunctionType() || 5995 T->isVariablyModifiedType() || 5996 T->isDependentType()) 5997 return Error(E); 5998 5999 CharUnits Size = Info.Ctx.getTypeSizeInChars(T); 6000 CharUnits Offset = Base.getLValueOffset(); 6001 6002 if (!Offset.isNegative() && Offset <= Size) 6003 Size -= Offset; 6004 else 6005 Size = CharUnits::Zero(); 6006 return Success(Size, E); 6007} 6008 6009bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) { 6010 switch (unsigned BuiltinOp = E->getBuiltinCallee()) { 6011 default: 6012 return ExprEvaluatorBaseTy::VisitCallExpr(E); 6013 6014 case Builtin::BI__builtin_object_size: { 6015 if (TryEvaluateBuiltinObjectSize(E)) 6016 return true; 6017 6018 // If evaluating the argument has side-effects, we can't determine the size 6019 // of the object, and so we lower it to unknown now. CodeGen relies on us to 6020 // handle all cases where the expression has side-effects. 6021 if (E->getArg(0)->HasSideEffects(Info.Ctx)) { 6022 if (E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue() <= 1) 6023 return Success(-1ULL, E); 6024 return Success(0, E); 6025 } 6026 6027 // Expression had no side effects, but we couldn't statically determine the 6028 // size of the referenced object. 6029 switch (Info.EvalMode) { 6030 case EvalInfo::EM_ConstantExpression: 6031 case EvalInfo::EM_PotentialConstantExpression: 6032 case EvalInfo::EM_ConstantFold: 6033 case EvalInfo::EM_EvaluateForOverflow: 6034 case EvalInfo::EM_IgnoreSideEffects: 6035 return Error(E); 6036 case EvalInfo::EM_ConstantExpressionUnevaluated: 6037 case EvalInfo::EM_PotentialConstantExpressionUnevaluated: 6038 return Success(-1ULL, E); 6039 } 6040 } 6041 6042 case Builtin::BI__builtin_bswap16: 6043 case Builtin::BI__builtin_bswap32: 6044 case Builtin::BI__builtin_bswap64: { 6045 APSInt Val; 6046 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6047 return false; 6048 6049 return Success(Val.byteSwap(), E); 6050 } 6051 6052 case Builtin::BI__builtin_classify_type: 6053 return Success(EvaluateBuiltinClassifyType(E), E); 6054 6055 // FIXME: BI__builtin_clrsb 6056 // FIXME: BI__builtin_clrsbl 6057 // FIXME: BI__builtin_clrsbll 6058 6059 case Builtin::BI__builtin_clz: 6060 case Builtin::BI__builtin_clzl: 6061 case Builtin::BI__builtin_clzll: 6062 case Builtin::BI__builtin_clzs: { 6063 APSInt Val; 6064 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6065 return false; 6066 if (!Val) 6067 return Error(E); 6068 6069 return Success(Val.countLeadingZeros(), E); 6070 } 6071 6072 case Builtin::BI__builtin_constant_p: 6073 return Success(EvaluateBuiltinConstantP(Info.Ctx, E->getArg(0)), E); 6074 6075 case Builtin::BI__builtin_ctz: 6076 case Builtin::BI__builtin_ctzl: 6077 case Builtin::BI__builtin_ctzll: 6078 case Builtin::BI__builtin_ctzs: { 6079 APSInt Val; 6080 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6081 return false; 6082 if (!Val) 6083 return Error(E); 6084 6085 return Success(Val.countTrailingZeros(), E); 6086 } 6087 6088 case Builtin::BI__builtin_eh_return_data_regno: { 6089 int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); 6090 Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand); 6091 return Success(Operand, E); 6092 } 6093 6094 case Builtin::BI__builtin_expect: 6095 return Visit(E->getArg(0)); 6096 6097 case Builtin::BI__builtin_ffs: 6098 case Builtin::BI__builtin_ffsl: 6099 case Builtin::BI__builtin_ffsll: { 6100 APSInt Val; 6101 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6102 return false; 6103 6104 unsigned N = Val.countTrailingZeros(); 6105 return Success(N == Val.getBitWidth() ? 0 : N + 1, E); 6106 } 6107 6108 case Builtin::BI__builtin_fpclassify: { 6109 APFloat Val(0.0); 6110 if (!EvaluateFloat(E->getArg(5), Val, Info)) 6111 return false; 6112 unsigned Arg; 6113 switch (Val.getCategory()) { 6114 case APFloat::fcNaN: Arg = 0; break; 6115 case APFloat::fcInfinity: Arg = 1; break; 6116 case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break; 6117 case APFloat::fcZero: Arg = 4; break; 6118 } 6119 return Visit(E->getArg(Arg)); 6120 } 6121 6122 case Builtin::BI__builtin_isinf_sign: { 6123 APFloat Val(0.0); 6124 return EvaluateFloat(E->getArg(0), Val, Info) && 6125 Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E); 6126 } 6127 6128 case Builtin::BI__builtin_isinf: { 6129 APFloat Val(0.0); 6130 return EvaluateFloat(E->getArg(0), Val, Info) && 6131 Success(Val.isInfinity() ? 1 : 0, E); 6132 } 6133 6134 case Builtin::BI__builtin_isfinite: { 6135 APFloat Val(0.0); 6136 return EvaluateFloat(E->getArg(0), Val, Info) && 6137 Success(Val.isFinite() ? 1 : 0, E); 6138 } 6139 6140 case Builtin::BI__builtin_isnan: { 6141 APFloat Val(0.0); 6142 return EvaluateFloat(E->getArg(0), Val, Info) && 6143 Success(Val.isNaN() ? 1 : 0, E); 6144 } 6145 6146 case Builtin::BI__builtin_isnormal: { 6147 APFloat Val(0.0); 6148 return EvaluateFloat(E->getArg(0), Val, Info) && 6149 Success(Val.isNormal() ? 1 : 0, E); 6150 } 6151 6152 case Builtin::BI__builtin_parity: 6153 case Builtin::BI__builtin_parityl: 6154 case Builtin::BI__builtin_parityll: { 6155 APSInt Val; 6156 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6157 return false; 6158 6159 return Success(Val.countPopulation() % 2, E); 6160 } 6161 6162 case Builtin::BI__builtin_popcount: 6163 case Builtin::BI__builtin_popcountl: 6164 case Builtin::BI__builtin_popcountll: { 6165 APSInt Val; 6166 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6167 return false; 6168 6169 return Success(Val.countPopulation(), E); 6170 } 6171 6172 case Builtin::BIstrlen: 6173 // A call to strlen is not a constant expression. 6174 if (Info.getLangOpts().CPlusPlus11) 6175 Info.CCEDiag(E, diag::note_constexpr_invalid_function) 6176 << /*isConstexpr*/0 << /*isConstructor*/0 << "'strlen'"; 6177 else 6178 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 6179 // Fall through. 6180 case Builtin::BI__builtin_strlen: { 6181 // As an extension, we support __builtin_strlen() as a constant expression, 6182 // and support folding strlen() to a constant. 6183 LValue String; 6184 if (!EvaluatePointer(E->getArg(0), String, Info)) 6185 return false; 6186 6187 // Fast path: if it's a string literal, search the string value. 6188 if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>( 6189 String.getLValueBase().dyn_cast<const Expr *>())) { 6190 // The string literal may have embedded null characters. Find the first 6191 // one and truncate there. 6192 StringRef Str = S->getBytes(); 6193 int64_t Off = String.Offset.getQuantity(); 6194 if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() && 6195 S->getCharByteWidth() == 1) { 6196 Str = Str.substr(Off); 6197 6198 StringRef::size_type Pos = Str.find(0); 6199 if (Pos != StringRef::npos) 6200 Str = Str.substr(0, Pos); 6201 6202 return Success(Str.size(), E); 6203 } 6204 6205 // Fall through to slow path to issue appropriate diagnostic. 6206 } 6207 6208 // Slow path: scan the bytes of the string looking for the terminating 0. 6209 QualType CharTy = E->getArg(0)->getType()->getPointeeType(); 6210 for (uint64_t Strlen = 0; /**/; ++Strlen) { 6211 APValue Char; 6212 if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) || 6213 !Char.isInt()) 6214 return false; 6215 if (!Char.getInt()) 6216 return Success(Strlen, E); 6217 if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1)) 6218 return false; 6219 } 6220 } 6221 6222 case Builtin::BI__atomic_always_lock_free: 6223 case Builtin::BI__atomic_is_lock_free: 6224 case Builtin::BI__c11_atomic_is_lock_free: { 6225 APSInt SizeVal; 6226 if (!EvaluateInteger(E->getArg(0), SizeVal, Info)) 6227 return false; 6228 6229 // For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power 6230 // of two less than the maximum inline atomic width, we know it is 6231 // lock-free. If the size isn't a power of two, or greater than the 6232 // maximum alignment where we promote atomics, we know it is not lock-free 6233 // (at least not in the sense of atomic_is_lock_free). Otherwise, 6234 // the answer can only be determined at runtime; for example, 16-byte 6235 // atomics have lock-free implementations on some, but not all, 6236 // x86-64 processors. 6237 6238 // Check power-of-two. 6239 CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue()); 6240 if (Size.isPowerOfTwo()) { 6241 // Check against inlining width. 6242 unsigned InlineWidthBits = 6243 Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth(); 6244 if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) { 6245 if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free || 6246 Size == CharUnits::One() || 6247 E->getArg(1)->isNullPointerConstant(Info.Ctx, 6248 Expr::NPC_NeverValueDependent)) 6249 // OK, we will inline appropriately-aligned operations of this size, 6250 // and _Atomic(T) is appropriately-aligned. 6251 return Success(1, E); 6252 6253 QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()-> 6254 castAs<PointerType>()->getPointeeType(); 6255 if (!PointeeType->isIncompleteType() && 6256 Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) { 6257 // OK, we will inline operations on this object. 6258 return Success(1, E); 6259 } 6260 } 6261 } 6262 6263 return BuiltinOp == Builtin::BI__atomic_always_lock_free ? 6264 Success(0, E) : Error(E); 6265 } 6266 } 6267} 6268 6269static bool HasSameBase(const LValue &A, const LValue &B) { 6270 if (!A.getLValueBase()) 6271 return !B.getLValueBase(); 6272 if (!B.getLValueBase()) 6273 return false; 6274 6275 if (A.getLValueBase().getOpaqueValue() != 6276 B.getLValueBase().getOpaqueValue()) { 6277 const Decl *ADecl = GetLValueBaseDecl(A); 6278 if (!ADecl) 6279 return false; 6280 const Decl *BDecl = GetLValueBaseDecl(B); 6281 if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl()) 6282 return false; 6283 } 6284 6285 return IsGlobalLValue(A.getLValueBase()) || 6286 A.getLValueCallIndex() == B.getLValueCallIndex(); 6287} 6288 6289namespace { 6290 6291/// \brief Data recursive integer evaluator of certain binary operators. 6292/// 6293/// We use a data recursive algorithm for binary operators so that we are able 6294/// to handle extreme cases of chained binary operators without causing stack 6295/// overflow. 6296class DataRecursiveIntBinOpEvaluator { 6297 struct EvalResult { 6298 APValue Val; 6299 bool Failed; 6300 6301 EvalResult() : Failed(false) { } 6302 6303 void swap(EvalResult &RHS) { 6304 Val.swap(RHS.Val); 6305 Failed = RHS.Failed; 6306 RHS.Failed = false; 6307 } 6308 }; 6309 6310 struct Job { 6311 const Expr *E; 6312 EvalResult LHSResult; // meaningful only for binary operator expression. 6313 enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind; 6314 6315 Job() : StoredInfo(nullptr) {} 6316 void startSpeculativeEval(EvalInfo &Info) { 6317 OldEvalStatus = Info.EvalStatus; 6318 Info.EvalStatus.Diag = nullptr; 6319 StoredInfo = &Info; 6320 } 6321 ~Job() { 6322 if (StoredInfo) { 6323 StoredInfo->EvalStatus = OldEvalStatus; 6324 } 6325 } 6326 private: 6327 EvalInfo *StoredInfo; // non-null if status changed. 6328 Expr::EvalStatus OldEvalStatus; 6329 }; 6330 6331 SmallVector<Job, 16> Queue; 6332 6333 IntExprEvaluator &IntEval; 6334 EvalInfo &Info; 6335 APValue &FinalResult; 6336 6337public: 6338 DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result) 6339 : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { } 6340 6341 /// \brief True if \param E is a binary operator that we are going to handle 6342 /// data recursively. 6343 /// We handle binary operators that are comma, logical, or that have operands 6344 /// with integral or enumeration type. 6345 static bool shouldEnqueue(const BinaryOperator *E) { 6346 return E->getOpcode() == BO_Comma || 6347 E->isLogicalOp() || 6348 (E->getLHS()->getType()->isIntegralOrEnumerationType() && 6349 E->getRHS()->getType()->isIntegralOrEnumerationType()); 6350 } 6351 6352 bool Traverse(const BinaryOperator *E) { 6353 enqueue(E); 6354 EvalResult PrevResult; 6355 while (!Queue.empty()) 6356 process(PrevResult); 6357 6358 if (PrevResult.Failed) return false; 6359 6360 FinalResult.swap(PrevResult.Val); 6361 return true; 6362 } 6363 6364private: 6365 bool Success(uint64_t Value, const Expr *E, APValue &Result) { 6366 return IntEval.Success(Value, E, Result); 6367 } 6368 bool Success(const APSInt &Value, const Expr *E, APValue &Result) { 6369 return IntEval.Success(Value, E, Result); 6370 } 6371 bool Error(const Expr *E) { 6372 return IntEval.Error(E); 6373 } 6374 bool Error(const Expr *E, diag::kind D) { 6375 return IntEval.Error(E, D); 6376 } 6377 6378 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { 6379 return Info.CCEDiag(E, D); 6380 } 6381 6382 // \brief Returns true if visiting the RHS is necessary, false otherwise. 6383 bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, 6384 bool &SuppressRHSDiags); 6385 6386 bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, 6387 const BinaryOperator *E, APValue &Result); 6388 6389 void EvaluateExpr(const Expr *E, EvalResult &Result) { 6390 Result.Failed = !Evaluate(Result.Val, Info, E); 6391 if (Result.Failed) 6392 Result.Val = APValue(); 6393 } 6394 6395 void process(EvalResult &Result); 6396 6397 void enqueue(const Expr *E) { 6398 E = E->IgnoreParens(); 6399 Queue.resize(Queue.size()+1); 6400 Queue.back().E = E; 6401 Queue.back().Kind = Job::AnyExprKind; 6402 } 6403}; 6404 6405} 6406 6407bool DataRecursiveIntBinOpEvaluator:: 6408 VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, 6409 bool &SuppressRHSDiags) { 6410 if (E->getOpcode() == BO_Comma) { 6411 // Ignore LHS but note if we could not evaluate it. 6412 if (LHSResult.Failed) 6413 return Info.noteSideEffect(); 6414 return true; 6415 } 6416 6417 if (E->isLogicalOp()) { 6418 bool LHSAsBool; 6419 if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) { 6420 // We were able to evaluate the LHS, see if we can get away with not 6421 // evaluating the RHS: 0 && X -> 0, 1 || X -> 1 6422 if (LHSAsBool == (E->getOpcode() == BO_LOr)) { 6423 Success(LHSAsBool, E, LHSResult.Val); 6424 return false; // Ignore RHS 6425 } 6426 } else { 6427 LHSResult.Failed = true; 6428 6429 // Since we weren't able to evaluate the left hand side, it 6430 // must have had side effects. 6431 if (!Info.noteSideEffect()) 6432 return false; 6433 6434 // We can't evaluate the LHS; however, sometimes the result 6435 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. 6436 // Don't ignore RHS and suppress diagnostics from this arm. 6437 SuppressRHSDiags = true; 6438 } 6439 6440 return true; 6441 } 6442 6443 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && 6444 E->getRHS()->getType()->isIntegralOrEnumerationType()); 6445 6446 if (LHSResult.Failed && !Info.keepEvaluatingAfterFailure()) 6447 return false; // Ignore RHS; 6448 6449 return true; 6450} 6451 6452bool DataRecursiveIntBinOpEvaluator:: 6453 VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, 6454 const BinaryOperator *E, APValue &Result) { 6455 if (E->getOpcode() == BO_Comma) { 6456 if (RHSResult.Failed) 6457 return false; 6458 Result = RHSResult.Val; 6459 return true; 6460 } 6461 6462 if (E->isLogicalOp()) { 6463 bool lhsResult, rhsResult; 6464 bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult); 6465 bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult); 6466 6467 if (LHSIsOK) { 6468 if (RHSIsOK) { 6469 if (E->getOpcode() == BO_LOr) 6470 return Success(lhsResult || rhsResult, E, Result); 6471 else 6472 return Success(lhsResult && rhsResult, E, Result); 6473 } 6474 } else { 6475 if (RHSIsOK) { 6476 // We can't evaluate the LHS; however, sometimes the result 6477 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. 6478 if (rhsResult == (E->getOpcode() == BO_LOr)) 6479 return Success(rhsResult, E, Result); 6480 } 6481 } 6482 6483 return false; 6484 } 6485 6486 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && 6487 E->getRHS()->getType()->isIntegralOrEnumerationType()); 6488 6489 if (LHSResult.Failed || RHSResult.Failed) 6490 return false; 6491 6492 const APValue &LHSVal = LHSResult.Val; 6493 const APValue &RHSVal = RHSResult.Val; 6494 6495 // Handle cases like (unsigned long)&a + 4. 6496 if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) { 6497 Result = LHSVal; 6498 CharUnits AdditionalOffset = 6499 CharUnits::fromQuantity(RHSVal.getInt().getZExtValue()); 6500 if (E->getOpcode() == BO_Add) 6501 Result.getLValueOffset() += AdditionalOffset; 6502 else 6503 Result.getLValueOffset() -= AdditionalOffset; 6504 return true; 6505 } 6506 6507 // Handle cases like 4 + (unsigned long)&a 6508 if (E->getOpcode() == BO_Add && 6509 RHSVal.isLValue() && LHSVal.isInt()) { 6510 Result = RHSVal; 6511 Result.getLValueOffset() += 6512 CharUnits::fromQuantity(LHSVal.getInt().getZExtValue()); 6513 return true; 6514 } 6515 6516 if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) { 6517 // Handle (intptr_t)&&A - (intptr_t)&&B. 6518 if (!LHSVal.getLValueOffset().isZero() || 6519 !RHSVal.getLValueOffset().isZero()) 6520 return false; 6521 const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>(); 6522 const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>(); 6523 if (!LHSExpr || !RHSExpr) 6524 return false; 6525 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); 6526 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); 6527 if (!LHSAddrExpr || !RHSAddrExpr) 6528 return false; 6529 // Make sure both labels come from the same function. 6530 if (LHSAddrExpr->getLabel()->getDeclContext() != 6531 RHSAddrExpr->getLabel()->getDeclContext()) 6532 return false; 6533 Result = APValue(LHSAddrExpr, RHSAddrExpr); 6534 return true; 6535 } 6536 6537 // All the remaining cases expect both operands to be an integer 6538 if (!LHSVal.isInt() || !RHSVal.isInt()) 6539 return Error(E); 6540 6541 // Set up the width and signedness manually, in case it can't be deduced 6542 // from the operation we're performing. 6543 // FIXME: Don't do this in the cases where we can deduce it. 6544 APSInt Value(Info.Ctx.getIntWidth(E->getType()), 6545 E->getType()->isUnsignedIntegerOrEnumerationType()); 6546 if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(), 6547 RHSVal.getInt(), Value)) 6548 return false; 6549 return Success(Value, E, Result); 6550} 6551 6552void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) { 6553 Job &job = Queue.back(); 6554 6555 switch (job.Kind) { 6556 case Job::AnyExprKind: { 6557 if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) { 6558 if (shouldEnqueue(Bop)) { 6559 job.Kind = Job::BinOpKind; 6560 enqueue(Bop->getLHS()); 6561 return; 6562 } 6563 } 6564 6565 EvaluateExpr(job.E, Result); 6566 Queue.pop_back(); 6567 return; 6568 } 6569 6570 case Job::BinOpKind: { 6571 const BinaryOperator *Bop = cast<BinaryOperator>(job.E); 6572 bool SuppressRHSDiags = false; 6573 if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) { 6574 Queue.pop_back(); 6575 return; 6576 } 6577 if (SuppressRHSDiags) 6578 job.startSpeculativeEval(Info); 6579 job.LHSResult.swap(Result); 6580 job.Kind = Job::BinOpVisitedLHSKind; 6581 enqueue(Bop->getRHS()); 6582 return; 6583 } 6584 6585 case Job::BinOpVisitedLHSKind: { 6586 const BinaryOperator *Bop = cast<BinaryOperator>(job.E); 6587 EvalResult RHS; 6588 RHS.swap(Result); 6589 Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val); 6590 Queue.pop_back(); 6591 return; 6592 } 6593 } 6594 6595 llvm_unreachable("Invalid Job::Kind!"); 6596} 6597 6598bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 6599 if (E->isAssignmentOp()) 6600 return Error(E); 6601 6602 if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E)) 6603 return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E); 6604 6605 QualType LHSTy = E->getLHS()->getType(); 6606 QualType RHSTy = E->getRHS()->getType(); 6607 6608 if (LHSTy->isAnyComplexType()) { 6609 assert(RHSTy->isAnyComplexType() && "Invalid comparison"); 6610 ComplexValue LHS, RHS; 6611 6612 bool LHSOK = EvaluateComplex(E->getLHS(), LHS, Info); 6613 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 6614 return false; 6615 6616 if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) 6617 return false; 6618 6619 if (LHS.isComplexFloat()) { 6620 APFloat::cmpResult CR_r = 6621 LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal()); 6622 APFloat::cmpResult CR_i = 6623 LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag()); 6624 6625 if (E->getOpcode() == BO_EQ) 6626 return Success((CR_r == APFloat::cmpEqual && 6627 CR_i == APFloat::cmpEqual), E); 6628 else { 6629 assert(E->getOpcode() == BO_NE && 6630 "Invalid complex comparison."); 6631 return Success(((CR_r == APFloat::cmpGreaterThan || 6632 CR_r == APFloat::cmpLessThan || 6633 CR_r == APFloat::cmpUnordered) || 6634 (CR_i == APFloat::cmpGreaterThan || 6635 CR_i == APFloat::cmpLessThan || 6636 CR_i == APFloat::cmpUnordered)), E); 6637 } 6638 } else { 6639 if (E->getOpcode() == BO_EQ) 6640 return Success((LHS.getComplexIntReal() == RHS.getComplexIntReal() && 6641 LHS.getComplexIntImag() == RHS.getComplexIntImag()), E); 6642 else { 6643 assert(E->getOpcode() == BO_NE && 6644 "Invalid compex comparison."); 6645 return Success((LHS.getComplexIntReal() != RHS.getComplexIntReal() || 6646 LHS.getComplexIntImag() != RHS.getComplexIntImag()), E); 6647 } 6648 } 6649 } 6650 6651 if (LHSTy->isRealFloatingType() && 6652 RHSTy->isRealFloatingType()) { 6653 APFloat RHS(0.0), LHS(0.0); 6654 6655 bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info); 6656 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 6657 return false; 6658 6659 if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK) 6660 return false; 6661 6662 APFloat::cmpResult CR = LHS.compare(RHS); 6663 6664 switch (E->getOpcode()) { 6665 default: 6666 llvm_unreachable("Invalid binary operator!"); 6667 case BO_LT: 6668 return Success(CR == APFloat::cmpLessThan, E); 6669 case BO_GT: 6670 return Success(CR == APFloat::cmpGreaterThan, E); 6671 case BO_LE: 6672 return Success(CR == APFloat::cmpLessThan || CR == APFloat::cmpEqual, E); 6673 case BO_GE: 6674 return Success(CR == APFloat::cmpGreaterThan || CR == APFloat::cmpEqual, 6675 E); 6676 case BO_EQ: 6677 return Success(CR == APFloat::cmpEqual, E); 6678 case BO_NE: 6679 return Success(CR == APFloat::cmpGreaterThan 6680 || CR == APFloat::cmpLessThan 6681 || CR == APFloat::cmpUnordered, E); 6682 } 6683 } 6684 6685 if (LHSTy->isPointerType() && RHSTy->isPointerType()) { 6686 if (E->getOpcode() == BO_Sub || E->isComparisonOp()) { 6687 LValue LHSValue, RHSValue; 6688 6689 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); 6690 if (!LHSOK && Info.keepEvaluatingAfterFailure()) 6691 return false; 6692 6693 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK) 6694 return false; 6695 6696 // Reject differing bases from the normal codepath; we special-case 6697 // comparisons to null. 6698 if (!HasSameBase(LHSValue, RHSValue)) { 6699 if (E->getOpcode() == BO_Sub) { 6700 // Handle &&A - &&B. 6701 if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero()) 6702 return false; 6703 const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr*>(); 6704 const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr*>(); 6705 if (!LHSExpr || !RHSExpr) 6706 return false; 6707 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); 6708 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); 6709 if (!LHSAddrExpr || !RHSAddrExpr) 6710 return false; 6711 // Make sure both labels come from the same function. 6712 if (LHSAddrExpr->getLabel()->getDeclContext() != 6713 RHSAddrExpr->getLabel()->getDeclContext()) 6714 return false; 6715 Result = APValue(LHSAddrExpr, RHSAddrExpr); 6716 return true; 6717 } 6718 // Inequalities and subtractions between unrelated pointers have 6719 // unspecified or undefined behavior. 6720 if (!E->isEqualityOp()) 6721 return Error(E); 6722 // A constant address may compare equal to the address of a symbol. 6723 // The one exception is that address of an object cannot compare equal 6724 // to a null pointer constant. 6725 if ((!LHSValue.Base && !LHSValue.Offset.isZero()) || 6726 (!RHSValue.Base && !RHSValue.Offset.isZero())) 6727 return Error(E); 6728 // It's implementation-defined whether distinct literals will have 6729 // distinct addresses. In clang, the result of such a comparison is 6730 // unspecified, so it is not a constant expression. However, we do know 6731 // that the address of a literal will be non-null. 6732 if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) && 6733 LHSValue.Base && RHSValue.Base) 6734 return Error(E); 6735 // We can't tell whether weak symbols will end up pointing to the same 6736 // object. 6737 if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue)) 6738 return Error(E); 6739 // Pointers with different bases cannot represent the same object. 6740 // (Note that clang defaults to -fmerge-all-constants, which can 6741 // lead to inconsistent results for comparisons involving the address 6742 // of a constant; this generally doesn't matter in practice.) 6743 return Success(E->getOpcode() == BO_NE, E); 6744 } 6745 6746 const CharUnits &LHSOffset = LHSValue.getLValueOffset(); 6747 const CharUnits &RHSOffset = RHSValue.getLValueOffset(); 6748 6749 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); 6750 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); 6751 6752 if (E->getOpcode() == BO_Sub) { 6753 // C++11 [expr.add]p6: 6754 // Unless both pointers point to elements of the same array object, or 6755 // one past the last element of the array object, the behavior is 6756 // undefined. 6757 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && 6758 !AreElementsOfSameArray(getType(LHSValue.Base), 6759 LHSDesignator, RHSDesignator)) 6760 CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array); 6761 6762 QualType Type = E->getLHS()->getType(); 6763 QualType ElementType = Type->getAs<PointerType>()->getPointeeType(); 6764 6765 CharUnits ElementSize; 6766 if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize)) 6767 return false; 6768 6769 // As an extension, a type may have zero size (empty struct or union in 6770 // C, array of zero length). Pointer subtraction in such cases has 6771 // undefined behavior, so is not constant. 6772 if (ElementSize.isZero()) { 6773 Info.Diag(E, diag::note_constexpr_pointer_subtraction_zero_size) 6774 << ElementType; 6775 return false; 6776 } 6777 6778 // FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime, 6779 // and produce incorrect results when it overflows. Such behavior 6780 // appears to be non-conforming, but is common, so perhaps we should 6781 // assume the standard intended for such cases to be undefined behavior 6782 // and check for them. 6783 6784 // Compute (LHSOffset - RHSOffset) / Size carefully, checking for 6785 // overflow in the final conversion to ptrdiff_t. 6786 APSInt LHS( 6787 llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false); 6788 APSInt RHS( 6789 llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false); 6790 APSInt ElemSize( 6791 llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true), false); 6792 APSInt TrueResult = (LHS - RHS) / ElemSize; 6793 APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType())); 6794 6795 if (Result.extend(65) != TrueResult) 6796 HandleOverflow(Info, E, TrueResult, E->getType()); 6797 return Success(Result, E); 6798 } 6799 6800 // C++11 [expr.rel]p3: 6801 // Pointers to void (after pointer conversions) can be compared, with a 6802 // result defined as follows: If both pointers represent the same 6803 // address or are both the null pointer value, the result is true if the 6804 // operator is <= or >= and false otherwise; otherwise the result is 6805 // unspecified. 6806 // We interpret this as applying to pointers to *cv* void. 6807 if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && 6808 E->isRelationalOp()) 6809 CCEDiag(E, diag::note_constexpr_void_comparison); 6810 6811 // C++11 [expr.rel]p2: 6812 // - If two pointers point to non-static data members of the same object, 6813 // or to subobjects or array elements fo such members, recursively, the 6814 // pointer to the later declared member compares greater provided the 6815 // two members have the same access control and provided their class is 6816 // not a union. 6817 // [...] 6818 // - Otherwise pointer comparisons are unspecified. 6819 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && 6820 E->isRelationalOp()) { 6821 bool WasArrayIndex; 6822 unsigned Mismatch = 6823 FindDesignatorMismatch(getType(LHSValue.Base), LHSDesignator, 6824 RHSDesignator, WasArrayIndex); 6825 // At the point where the designators diverge, the comparison has a 6826 // specified value if: 6827 // - we are comparing array indices 6828 // - we are comparing fields of a union, or fields with the same access 6829 // Otherwise, the result is unspecified and thus the comparison is not a 6830 // constant expression. 6831 if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() && 6832 Mismatch < RHSDesignator.Entries.size()) { 6833 const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]); 6834 const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]); 6835 if (!LF && !RF) 6836 CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes); 6837 else if (!LF) 6838 CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) 6839 << getAsBaseClass(LHSDesignator.Entries[Mismatch]) 6840 << RF->getParent() << RF; 6841 else if (!RF) 6842 CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) 6843 << getAsBaseClass(RHSDesignator.Entries[Mismatch]) 6844 << LF->getParent() << LF; 6845 else if (!LF->getParent()->isUnion() && 6846 LF->getAccess() != RF->getAccess()) 6847 CCEDiag(E, diag::note_constexpr_pointer_comparison_differing_access) 6848 << LF << LF->getAccess() << RF << RF->getAccess() 6849 << LF->getParent(); 6850 } 6851 } 6852 6853 // The comparison here must be unsigned, and performed with the same 6854 // width as the pointer. 6855 unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy); 6856 uint64_t CompareLHS = LHSOffset.getQuantity(); 6857 uint64_t CompareRHS = RHSOffset.getQuantity(); 6858 assert(PtrSize <= 64 && "Unexpected pointer width"); 6859 uint64_t Mask = ~0ULL >> (64 - PtrSize); 6860 CompareLHS &= Mask; 6861 CompareRHS &= Mask; 6862 6863 // If there is a base and this is a relational operator, we can only 6864 // compare pointers within the object in question; otherwise, the result 6865 // depends on where the object is located in memory. 6866 if (!LHSValue.Base.isNull() && E->isRelationalOp()) { 6867 QualType BaseTy = getType(LHSValue.Base); 6868 if (BaseTy->isIncompleteType()) 6869 return Error(E); 6870 CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy); 6871 uint64_t OffsetLimit = Size.getQuantity(); 6872 if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit) 6873 return Error(E); 6874 } 6875 6876 switch (E->getOpcode()) { 6877 default: llvm_unreachable("missing comparison operator"); 6878 case BO_LT: return Success(CompareLHS < CompareRHS, E); 6879 case BO_GT: return Success(CompareLHS > CompareRHS, E); 6880 case BO_LE: return Success(CompareLHS <= CompareRHS, E); 6881 case BO_GE: return Success(CompareLHS >= CompareRHS, E); 6882 case BO_EQ: return Success(CompareLHS == CompareRHS, E); 6883 case BO_NE: return Success(CompareLHS != CompareRHS, E); 6884 } 6885 } 6886 } 6887 6888 if (LHSTy->isMemberPointerType()) { 6889 assert(E->isEqualityOp() && "unexpected member pointer operation"); 6890 assert(RHSTy->isMemberPointerType() && "invalid comparison"); 6891 6892 MemberPtr LHSValue, RHSValue; 6893 6894 bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info); 6895 if (!LHSOK && Info.keepEvaluatingAfterFailure()) 6896 return false; 6897 6898 if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK) 6899 return false; 6900 6901 // C++11 [expr.eq]p2: 6902 // If both operands are null, they compare equal. Otherwise if only one is 6903 // null, they compare unequal. 6904 if (!LHSValue.getDecl() || !RHSValue.getDecl()) { 6905 bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl(); 6906 return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E); 6907 } 6908 6909 // Otherwise if either is a pointer to a virtual member function, the 6910 // result is unspecified. 6911 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl())) 6912 if (MD->isVirtual()) 6913 CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; 6914 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl())) 6915 if (MD->isVirtual()) 6916 CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; 6917 6918 // Otherwise they compare equal if and only if they would refer to the 6919 // same member of the same most derived object or the same subobject if 6920 // they were dereferenced with a hypothetical object of the associated 6921 // class type. 6922 bool Equal = LHSValue == RHSValue; 6923 return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E); 6924 } 6925 6926 if (LHSTy->isNullPtrType()) { 6927 assert(E->isComparisonOp() && "unexpected nullptr operation"); 6928 assert(RHSTy->isNullPtrType() && "missing pointer conversion"); 6929 // C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t 6930 // are compared, the result is true of the operator is <=, >= or ==, and 6931 // false otherwise. 6932 BinaryOperator::Opcode Opcode = E->getOpcode(); 6933 return Success(Opcode == BO_EQ || Opcode == BO_LE || Opcode == BO_GE, E); 6934 } 6935 6936 assert((!LHSTy->isIntegralOrEnumerationType() || 6937 !RHSTy->isIntegralOrEnumerationType()) && 6938 "DataRecursiveIntBinOpEvaluator should have handled integral types"); 6939 // We can't continue from here for non-integral types. 6940 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 6941} 6942 6943CharUnits IntExprEvaluator::GetAlignOfType(QualType T) { 6944 // C++ [expr.alignof]p3: 6945 // When alignof is applied to a reference type, the result is the 6946 // alignment of the referenced type. 6947 if (const ReferenceType *Ref = T->getAs<ReferenceType>()) 6948 T = Ref->getPointeeType(); 6949 6950 // __alignof is defined to return the preferred alignment. 6951 return Info.Ctx.toCharUnitsFromBits( 6952 Info.Ctx.getPreferredTypeAlign(T.getTypePtr())); 6953} 6954 6955CharUnits IntExprEvaluator::GetAlignOfExpr(const Expr *E) { 6956 E = E->IgnoreParens(); 6957 6958 // The kinds of expressions that we have special-case logic here for 6959 // should be kept up to date with the special checks for those 6960 // expressions in Sema. 6961 6962 // alignof decl is always accepted, even if it doesn't make sense: we default 6963 // to 1 in those cases. 6964 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) 6965 return Info.Ctx.getDeclAlign(DRE->getDecl(), 6966 /*RefAsPointee*/true); 6967 6968 if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) 6969 return Info.Ctx.getDeclAlign(ME->getMemberDecl(), 6970 /*RefAsPointee*/true); 6971 6972 return GetAlignOfType(E->getType()); 6973} 6974 6975 6976/// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with 6977/// a result as the expression's type. 6978bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr( 6979 const UnaryExprOrTypeTraitExpr *E) { 6980 switch(E->getKind()) { 6981 case UETT_AlignOf: { 6982 if (E->isArgumentType()) 6983 return Success(GetAlignOfType(E->getArgumentType()), E); 6984 else 6985 return Success(GetAlignOfExpr(E->getArgumentExpr()), E); 6986 } 6987 6988 case UETT_VecStep: { 6989 QualType Ty = E->getTypeOfArgument(); 6990 6991 if (Ty->isVectorType()) { 6992 unsigned n = Ty->castAs<VectorType>()->getNumElements(); 6993 6994 // The vec_step built-in functions that take a 3-component 6995 // vector return 4. (OpenCL 1.1 spec 6.11.12) 6996 if (n == 3) 6997 n = 4; 6998 6999 return Success(n, E); 7000 } else 7001 return Success(1, E); 7002 } 7003 7004 case UETT_SizeOf: { 7005 QualType SrcTy = E->getTypeOfArgument(); 7006 // C++ [expr.sizeof]p2: "When applied to a reference or a reference type, 7007 // the result is the size of the referenced type." 7008 if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>()) 7009 SrcTy = Ref->getPointeeType(); 7010 7011 CharUnits Sizeof; 7012 if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof)) 7013 return false; 7014 return Success(Sizeof, E); 7015 } 7016 } 7017 7018 llvm_unreachable("unknown expr/type trait"); 7019} 7020 7021bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) { 7022 CharUnits Result; 7023 unsigned n = OOE->getNumComponents(); 7024 if (n == 0) 7025 return Error(OOE); 7026 QualType CurrentType = OOE->getTypeSourceInfo()->getType(); 7027 for (unsigned i = 0; i != n; ++i) { 7028 OffsetOfExpr::OffsetOfNode ON = OOE->getComponent(i); 7029 switch (ON.getKind()) { 7030 case OffsetOfExpr::OffsetOfNode::Array: { 7031 const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex()); 7032 APSInt IdxResult; 7033 if (!EvaluateInteger(Idx, IdxResult, Info)) 7034 return false; 7035 const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType); 7036 if (!AT) 7037 return Error(OOE); 7038 CurrentType = AT->getElementType(); 7039 CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType); 7040 Result += IdxResult.getSExtValue() * ElementSize; 7041 break; 7042 } 7043 7044 case OffsetOfExpr::OffsetOfNode::Field: { 7045 FieldDecl *MemberDecl = ON.getField(); 7046 const RecordType *RT = CurrentType->getAs<RecordType>(); 7047 if (!RT) 7048 return Error(OOE); 7049 RecordDecl *RD = RT->getDecl(); 7050 if (RD->isInvalidDecl()) return false; 7051 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); 7052 unsigned i = MemberDecl->getFieldIndex(); 7053 assert(i < RL.getFieldCount() && "offsetof field in wrong type"); 7054 Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i)); 7055 CurrentType = MemberDecl->getType().getNonReferenceType(); 7056 break; 7057 } 7058 7059 case OffsetOfExpr::OffsetOfNode::Identifier: 7060 llvm_unreachable("dependent __builtin_offsetof"); 7061 7062 case OffsetOfExpr::OffsetOfNode::Base: { 7063 CXXBaseSpecifier *BaseSpec = ON.getBase(); 7064 if (BaseSpec->isVirtual()) 7065 return Error(OOE); 7066 7067 // Find the layout of the class whose base we are looking into. 7068 const RecordType *RT = CurrentType->getAs<RecordType>(); 7069 if (!RT) 7070 return Error(OOE); 7071 RecordDecl *RD = RT->getDecl(); 7072 if (RD->isInvalidDecl()) return false; 7073 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); 7074 7075 // Find the base class itself. 7076 CurrentType = BaseSpec->getType(); 7077 const RecordType *BaseRT = CurrentType->getAs<RecordType>(); 7078 if (!BaseRT) 7079 return Error(OOE); 7080 7081 // Add the offset to the base. 7082 Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl())); 7083 break; 7084 } 7085 } 7086 } 7087 return Success(Result, OOE); 7088} 7089 7090bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 7091 switch (E->getOpcode()) { 7092 default: 7093 // Address, indirect, pre/post inc/dec, etc are not valid constant exprs. 7094 // See C99 6.6p3. 7095 return Error(E); 7096 case UO_Extension: 7097 // FIXME: Should extension allow i-c-e extension expressions in its scope? 7098 // If so, we could clear the diagnostic ID. 7099 return Visit(E->getSubExpr()); 7100 case UO_Plus: 7101 // The result is just the value. 7102 return Visit(E->getSubExpr()); 7103 case UO_Minus: { 7104 if (!Visit(E->getSubExpr())) 7105 return false; 7106 if (!Result.isInt()) return Error(E); 7107 const APSInt &Value = Result.getInt(); 7108 if (Value.isSigned() && Value.isMinSignedValue()) 7109 HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1), 7110 E->getType()); 7111 return Success(-Value, E); 7112 } 7113 case UO_Not: { 7114 if (!Visit(E->getSubExpr())) 7115 return false; 7116 if (!Result.isInt()) return Error(E); 7117 return Success(~Result.getInt(), E); 7118 } 7119 case UO_LNot: { 7120 bool bres; 7121 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info)) 7122 return false; 7123 return Success(!bres, E); 7124 } 7125 } 7126} 7127 7128/// HandleCast - This is used to evaluate implicit or explicit casts where the 7129/// result type is integer. 7130bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) { 7131 const Expr *SubExpr = E->getSubExpr(); 7132 QualType DestType = E->getType(); 7133 QualType SrcType = SubExpr->getType(); 7134 7135 switch (E->getCastKind()) { 7136 case CK_BaseToDerived: 7137 case CK_DerivedToBase: 7138 case CK_UncheckedDerivedToBase: 7139 case CK_Dynamic: 7140 case CK_ToUnion: 7141 case CK_ArrayToPointerDecay: 7142 case CK_FunctionToPointerDecay: 7143 case CK_NullToPointer: 7144 case CK_NullToMemberPointer: 7145 case CK_BaseToDerivedMemberPointer: 7146 case CK_DerivedToBaseMemberPointer: 7147 case CK_ReinterpretMemberPointer: 7148 case CK_ConstructorConversion: 7149 case CK_IntegralToPointer: 7150 case CK_ToVoid: 7151 case CK_VectorSplat: 7152 case CK_IntegralToFloating: 7153 case CK_FloatingCast: 7154 case CK_CPointerToObjCPointerCast: 7155 case CK_BlockPointerToObjCPointerCast: 7156 case CK_AnyPointerToBlockPointerCast: 7157 case CK_ObjCObjectLValueCast: 7158 case CK_FloatingRealToComplex: 7159 case CK_FloatingComplexToReal: 7160 case CK_FloatingComplexCast: 7161 case CK_FloatingComplexToIntegralComplex: 7162 case CK_IntegralRealToComplex: 7163 case CK_IntegralComplexCast: 7164 case CK_IntegralComplexToFloatingComplex: 7165 case CK_BuiltinFnToFnPtr: 7166 case CK_ZeroToOCLEvent: 7167 case CK_NonAtomicToAtomic: 7168 case CK_AddressSpaceConversion: 7169 llvm_unreachable("invalid cast kind for integral value"); 7170 7171 case CK_BitCast: 7172 case CK_Dependent: 7173 case CK_LValueBitCast: 7174 case CK_ARCProduceObject: 7175 case CK_ARCConsumeObject: 7176 case CK_ARCReclaimReturnedObject: 7177 case CK_ARCExtendBlockObject: 7178 case CK_CopyAndAutoreleaseBlockObject: 7179 return Error(E); 7180 7181 case CK_UserDefinedConversion: 7182 case CK_LValueToRValue: 7183 case CK_AtomicToNonAtomic: 7184 case CK_NoOp: 7185 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7186 7187 case CK_MemberPointerToBoolean: 7188 case CK_PointerToBoolean: 7189 case CK_IntegralToBoolean: 7190 case CK_FloatingToBoolean: 7191 case CK_FloatingComplexToBoolean: 7192 case CK_IntegralComplexToBoolean: { 7193 bool BoolResult; 7194 if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info)) 7195 return false; 7196 return Success(BoolResult, E); 7197 } 7198 7199 case CK_IntegralCast: { 7200 if (!Visit(SubExpr)) 7201 return false; 7202 7203 if (!Result.isInt()) { 7204 // Allow casts of address-of-label differences if they are no-ops 7205 // or narrowing. (The narrowing case isn't actually guaranteed to 7206 // be constant-evaluatable except in some narrow cases which are hard 7207 // to detect here. We let it through on the assumption the user knows 7208 // what they are doing.) 7209 if (Result.isAddrLabelDiff()) 7210 return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType); 7211 // Only allow casts of lvalues if they are lossless. 7212 return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType); 7213 } 7214 7215 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, 7216 Result.getInt()), E); 7217 } 7218 7219 case CK_PointerToIntegral: { 7220 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 7221 7222 LValue LV; 7223 if (!EvaluatePointer(SubExpr, LV, Info)) 7224 return false; 7225 7226 if (LV.getLValueBase()) { 7227 // Only allow based lvalue casts if they are lossless. 7228 // FIXME: Allow a larger integer size than the pointer size, and allow 7229 // narrowing back down to pointer width in subsequent integral casts. 7230 // FIXME: Check integer type's active bits, not its type size. 7231 if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType)) 7232 return Error(E); 7233 7234 LV.Designator.setInvalid(); 7235 LV.moveInto(Result); 7236 return true; 7237 } 7238 7239 APSInt AsInt = Info.Ctx.MakeIntValue(LV.getLValueOffset().getQuantity(), 7240 SrcType); 7241 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E); 7242 } 7243 7244 case CK_IntegralComplexToReal: { 7245 ComplexValue C; 7246 if (!EvaluateComplex(SubExpr, C, Info)) 7247 return false; 7248 return Success(C.getComplexIntReal(), E); 7249 } 7250 7251 case CK_FloatingToIntegral: { 7252 APFloat F(0.0); 7253 if (!EvaluateFloat(SubExpr, F, Info)) 7254 return false; 7255 7256 APSInt Value; 7257 if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value)) 7258 return false; 7259 return Success(Value, E); 7260 } 7261 } 7262 7263 llvm_unreachable("unknown cast resulting in integral value"); 7264} 7265 7266bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 7267 if (E->getSubExpr()->getType()->isAnyComplexType()) { 7268 ComplexValue LV; 7269 if (!EvaluateComplex(E->getSubExpr(), LV, Info)) 7270 return false; 7271 if (!LV.isComplexInt()) 7272 return Error(E); 7273 return Success(LV.getComplexIntReal(), E); 7274 } 7275 7276 return Visit(E->getSubExpr()); 7277} 7278 7279bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 7280 if (E->getSubExpr()->getType()->isComplexIntegerType()) { 7281 ComplexValue LV; 7282 if (!EvaluateComplex(E->getSubExpr(), LV, Info)) 7283 return false; 7284 if (!LV.isComplexInt()) 7285 return Error(E); 7286 return Success(LV.getComplexIntImag(), E); 7287 } 7288 7289 VisitIgnoredValue(E->getSubExpr()); 7290 return Success(0, E); 7291} 7292 7293bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) { 7294 return Success(E->getPackLength(), E); 7295} 7296 7297bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) { 7298 return Success(E->getValue(), E); 7299} 7300 7301//===----------------------------------------------------------------------===// 7302// Float Evaluation 7303//===----------------------------------------------------------------------===// 7304 7305namespace { 7306class FloatExprEvaluator 7307 : public ExprEvaluatorBase<FloatExprEvaluator> { 7308 APFloat &Result; 7309public: 7310 FloatExprEvaluator(EvalInfo &info, APFloat &result) 7311 : ExprEvaluatorBaseTy(info), Result(result) {} 7312 7313 bool Success(const APValue &V, const Expr *e) { 7314 Result = V.getFloat(); 7315 return true; 7316 } 7317 7318 bool ZeroInitialization(const Expr *E) { 7319 Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType())); 7320 return true; 7321 } 7322 7323 bool VisitCallExpr(const CallExpr *E); 7324 7325 bool VisitUnaryOperator(const UnaryOperator *E); 7326 bool VisitBinaryOperator(const BinaryOperator *E); 7327 bool VisitFloatingLiteral(const FloatingLiteral *E); 7328 bool VisitCastExpr(const CastExpr *E); 7329 7330 bool VisitUnaryReal(const UnaryOperator *E); 7331 bool VisitUnaryImag(const UnaryOperator *E); 7332 7333 // FIXME: Missing: array subscript of vector, member of vector 7334}; 7335} // end anonymous namespace 7336 7337static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) { 7338 assert(E->isRValue() && E->getType()->isRealFloatingType()); 7339 return FloatExprEvaluator(Info, Result).Visit(E); 7340} 7341 7342static bool TryEvaluateBuiltinNaN(const ASTContext &Context, 7343 QualType ResultTy, 7344 const Expr *Arg, 7345 bool SNaN, 7346 llvm::APFloat &Result) { 7347 const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts()); 7348 if (!S) return false; 7349 7350 const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy); 7351 7352 llvm::APInt fill; 7353 7354 // Treat empty strings as if they were zero. 7355 if (S->getString().empty()) 7356 fill = llvm::APInt(32, 0); 7357 else if (S->getString().getAsInteger(0, fill)) 7358 return false; 7359 7360 if (SNaN) 7361 Result = llvm::APFloat::getSNaN(Sem, false, &fill); 7362 else 7363 Result = llvm::APFloat::getQNaN(Sem, false, &fill); 7364 return true; 7365} 7366 7367bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) { 7368 switch (E->getBuiltinCallee()) { 7369 default: 7370 return ExprEvaluatorBaseTy::VisitCallExpr(E); 7371 7372 case Builtin::BI__builtin_huge_val: 7373 case Builtin::BI__builtin_huge_valf: 7374 case Builtin::BI__builtin_huge_vall: 7375 case Builtin::BI__builtin_inf: 7376 case Builtin::BI__builtin_inff: 7377 case Builtin::BI__builtin_infl: { 7378 const llvm::fltSemantics &Sem = 7379 Info.Ctx.getFloatTypeSemantics(E->getType()); 7380 Result = llvm::APFloat::getInf(Sem); 7381 return true; 7382 } 7383 7384 case Builtin::BI__builtin_nans: 7385 case Builtin::BI__builtin_nansf: 7386 case Builtin::BI__builtin_nansl: 7387 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), 7388 true, Result)) 7389 return Error(E); 7390 return true; 7391 7392 case Builtin::BI__builtin_nan: 7393 case Builtin::BI__builtin_nanf: 7394 case Builtin::BI__builtin_nanl: 7395 // If this is __builtin_nan() turn this into a nan, otherwise we 7396 // can't constant fold it. 7397 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), 7398 false, Result)) 7399 return Error(E); 7400 return true; 7401 7402 case Builtin::BI__builtin_fabs: 7403 case Builtin::BI__builtin_fabsf: 7404 case Builtin::BI__builtin_fabsl: 7405 if (!EvaluateFloat(E->getArg(0), Result, Info)) 7406 return false; 7407 7408 if (Result.isNegative()) 7409 Result.changeSign(); 7410 return true; 7411 7412 // FIXME: Builtin::BI__builtin_powi 7413 // FIXME: Builtin::BI__builtin_powif 7414 // FIXME: Builtin::BI__builtin_powil 7415 7416 case Builtin::BI__builtin_copysign: 7417 case Builtin::BI__builtin_copysignf: 7418 case Builtin::BI__builtin_copysignl: { 7419 APFloat RHS(0.); 7420 if (!EvaluateFloat(E->getArg(0), Result, Info) || 7421 !EvaluateFloat(E->getArg(1), RHS, Info)) 7422 return false; 7423 Result.copySign(RHS); 7424 return true; 7425 } 7426 } 7427} 7428 7429bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 7430 if (E->getSubExpr()->getType()->isAnyComplexType()) { 7431 ComplexValue CV; 7432 if (!EvaluateComplex(E->getSubExpr(), CV, Info)) 7433 return false; 7434 Result = CV.FloatReal; 7435 return true; 7436 } 7437 7438 return Visit(E->getSubExpr()); 7439} 7440 7441bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 7442 if (E->getSubExpr()->getType()->isAnyComplexType()) { 7443 ComplexValue CV; 7444 if (!EvaluateComplex(E->getSubExpr(), CV, Info)) 7445 return false; 7446 Result = CV.FloatImag; 7447 return true; 7448 } 7449 7450 VisitIgnoredValue(E->getSubExpr()); 7451 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType()); 7452 Result = llvm::APFloat::getZero(Sem); 7453 return true; 7454} 7455 7456bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 7457 switch (E->getOpcode()) { 7458 default: return Error(E); 7459 case UO_Plus: 7460 return EvaluateFloat(E->getSubExpr(), Result, Info); 7461 case UO_Minus: 7462 if (!EvaluateFloat(E->getSubExpr(), Result, Info)) 7463 return false; 7464 Result.changeSign(); 7465 return true; 7466 } 7467} 7468 7469bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 7470 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) 7471 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 7472 7473 APFloat RHS(0.0); 7474 bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info); 7475 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 7476 return false; 7477 return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK && 7478 handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS); 7479} 7480 7481bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) { 7482 Result = E->getValue(); 7483 return true; 7484} 7485 7486bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) { 7487 const Expr* SubExpr = E->getSubExpr(); 7488 7489 switch (E->getCastKind()) { 7490 default: 7491 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7492 7493 case CK_IntegralToFloating: { 7494 APSInt IntResult; 7495 return EvaluateInteger(SubExpr, IntResult, Info) && 7496 HandleIntToFloatCast(Info, E, SubExpr->getType(), IntResult, 7497 E->getType(), Result); 7498 } 7499 7500 case CK_FloatingCast: { 7501 if (!Visit(SubExpr)) 7502 return false; 7503 return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(), 7504 Result); 7505 } 7506 7507 case CK_FloatingComplexToReal: { 7508 ComplexValue V; 7509 if (!EvaluateComplex(SubExpr, V, Info)) 7510 return false; 7511 Result = V.getComplexFloatReal(); 7512 return true; 7513 } 7514 } 7515} 7516 7517//===----------------------------------------------------------------------===// 7518// Complex Evaluation (for float and integer) 7519//===----------------------------------------------------------------------===// 7520 7521namespace { 7522class ComplexExprEvaluator 7523 : public ExprEvaluatorBase<ComplexExprEvaluator> { 7524 ComplexValue &Result; 7525 7526public: 7527 ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result) 7528 : ExprEvaluatorBaseTy(info), Result(Result) {} 7529 7530 bool Success(const APValue &V, const Expr *e) { 7531 Result.setFrom(V); 7532 return true; 7533 } 7534 7535 bool ZeroInitialization(const Expr *E); 7536 7537 //===--------------------------------------------------------------------===// 7538 // Visitor Methods 7539 //===--------------------------------------------------------------------===// 7540 7541 bool VisitImaginaryLiteral(const ImaginaryLiteral *E); 7542 bool VisitCastExpr(const CastExpr *E); 7543 bool VisitBinaryOperator(const BinaryOperator *E); 7544 bool VisitUnaryOperator(const UnaryOperator *E); 7545 bool VisitInitListExpr(const InitListExpr *E); 7546}; 7547} // end anonymous namespace 7548 7549static bool EvaluateComplex(const Expr *E, ComplexValue &Result, 7550 EvalInfo &Info) { 7551 assert(E->isRValue() && E->getType()->isAnyComplexType()); 7552 return ComplexExprEvaluator(Info, Result).Visit(E); 7553} 7554 7555bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) { 7556 QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType(); 7557 if (ElemTy->isRealFloatingType()) { 7558 Result.makeComplexFloat(); 7559 APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy)); 7560 Result.FloatReal = Zero; 7561 Result.FloatImag = Zero; 7562 } else { 7563 Result.makeComplexInt(); 7564 APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy); 7565 Result.IntReal = Zero; 7566 Result.IntImag = Zero; 7567 } 7568 return true; 7569} 7570 7571bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) { 7572 const Expr* SubExpr = E->getSubExpr(); 7573 7574 if (SubExpr->getType()->isRealFloatingType()) { 7575 Result.makeComplexFloat(); 7576 APFloat &Imag = Result.FloatImag; 7577 if (!EvaluateFloat(SubExpr, Imag, Info)) 7578 return false; 7579 7580 Result.FloatReal = APFloat(Imag.getSemantics()); 7581 return true; 7582 } else { 7583 assert(SubExpr->getType()->isIntegerType() && 7584 "Unexpected imaginary literal."); 7585 7586 Result.makeComplexInt(); 7587 APSInt &Imag = Result.IntImag; 7588 if (!EvaluateInteger(SubExpr, Imag, Info)) 7589 return false; 7590 7591 Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned()); 7592 return true; 7593 } 7594} 7595 7596bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) { 7597 7598 switch (E->getCastKind()) { 7599 case CK_BitCast: 7600 case CK_BaseToDerived: 7601 case CK_DerivedToBase: 7602 case CK_UncheckedDerivedToBase: 7603 case CK_Dynamic: 7604 case CK_ToUnion: 7605 case CK_ArrayToPointerDecay: 7606 case CK_FunctionToPointerDecay: 7607 case CK_NullToPointer: 7608 case CK_NullToMemberPointer: 7609 case CK_BaseToDerivedMemberPointer: 7610 case CK_DerivedToBaseMemberPointer: 7611 case CK_MemberPointerToBoolean: 7612 case CK_ReinterpretMemberPointer: 7613 case CK_ConstructorConversion: 7614 case CK_IntegralToPointer: 7615 case CK_PointerToIntegral: 7616 case CK_PointerToBoolean: 7617 case CK_ToVoid: 7618 case CK_VectorSplat: 7619 case CK_IntegralCast: 7620 case CK_IntegralToBoolean: 7621 case CK_IntegralToFloating: 7622 case CK_FloatingToIntegral: 7623 case CK_FloatingToBoolean: 7624 case CK_FloatingCast: 7625 case CK_CPointerToObjCPointerCast: 7626 case CK_BlockPointerToObjCPointerCast: 7627 case CK_AnyPointerToBlockPointerCast: 7628 case CK_ObjCObjectLValueCast: 7629 case CK_FloatingComplexToReal: 7630 case CK_FloatingComplexToBoolean: 7631 case CK_IntegralComplexToReal: 7632 case CK_IntegralComplexToBoolean: 7633 case CK_ARCProduceObject: 7634 case CK_ARCConsumeObject: 7635 case CK_ARCReclaimReturnedObject: 7636 case CK_ARCExtendBlockObject: 7637 case CK_CopyAndAutoreleaseBlockObject: 7638 case CK_BuiltinFnToFnPtr: 7639 case CK_ZeroToOCLEvent: 7640 case CK_NonAtomicToAtomic: 7641 case CK_AddressSpaceConversion: 7642 llvm_unreachable("invalid cast kind for complex value"); 7643 7644 case CK_LValueToRValue: 7645 case CK_AtomicToNonAtomic: 7646 case CK_NoOp: 7647 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7648 7649 case CK_Dependent: 7650 case CK_LValueBitCast: 7651 case CK_UserDefinedConversion: 7652 return Error(E); 7653 7654 case CK_FloatingRealToComplex: { 7655 APFloat &Real = Result.FloatReal; 7656 if (!EvaluateFloat(E->getSubExpr(), Real, Info)) 7657 return false; 7658 7659 Result.makeComplexFloat(); 7660 Result.FloatImag = APFloat(Real.getSemantics()); 7661 return true; 7662 } 7663 7664 case CK_FloatingComplexCast: { 7665 if (!Visit(E->getSubExpr())) 7666 return false; 7667 7668 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 7669 QualType From 7670 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 7671 7672 return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) && 7673 HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag); 7674 } 7675 7676 case CK_FloatingComplexToIntegralComplex: { 7677 if (!Visit(E->getSubExpr())) 7678 return false; 7679 7680 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 7681 QualType From 7682 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 7683 Result.makeComplexInt(); 7684 return HandleFloatToIntCast(Info, E, From, Result.FloatReal, 7685 To, Result.IntReal) && 7686 HandleFloatToIntCast(Info, E, From, Result.FloatImag, 7687 To, Result.IntImag); 7688 } 7689 7690 case CK_IntegralRealToComplex: { 7691 APSInt &Real = Result.IntReal; 7692 if (!EvaluateInteger(E->getSubExpr(), Real, Info)) 7693 return false; 7694 7695 Result.makeComplexInt(); 7696 Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned()); 7697 return true; 7698 } 7699 7700 case CK_IntegralComplexCast: { 7701 if (!Visit(E->getSubExpr())) 7702 return false; 7703 7704 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 7705 QualType From 7706 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 7707 7708 Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal); 7709 Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag); 7710 return true; 7711 } 7712 7713 case CK_IntegralComplexToFloatingComplex: { 7714 if (!Visit(E->getSubExpr())) 7715 return false; 7716 7717 QualType To = E->getType()->castAs<ComplexType>()->getElementType(); 7718 QualType From 7719 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType(); 7720 Result.makeComplexFloat(); 7721 return HandleIntToFloatCast(Info, E, From, Result.IntReal, 7722 To, Result.FloatReal) && 7723 HandleIntToFloatCast(Info, E, From, Result.IntImag, 7724 To, Result.FloatImag); 7725 } 7726 } 7727 7728 llvm_unreachable("unknown cast resulting in complex value"); 7729} 7730 7731bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 7732 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) 7733 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 7734 7735 bool LHSOK = Visit(E->getLHS()); 7736 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 7737 return false; 7738 7739 ComplexValue RHS; 7740 if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) 7741 return false; 7742 7743 assert(Result.isComplexFloat() == RHS.isComplexFloat() && 7744 "Invalid operands to binary operator."); 7745 switch (E->getOpcode()) { 7746 default: return Error(E); 7747 case BO_Add: 7748 if (Result.isComplexFloat()) { 7749 Result.getComplexFloatReal().add(RHS.getComplexFloatReal(), 7750 APFloat::rmNearestTiesToEven); 7751 Result.getComplexFloatImag().add(RHS.getComplexFloatImag(), 7752 APFloat::rmNearestTiesToEven); 7753 } else { 7754 Result.getComplexIntReal() += RHS.getComplexIntReal(); 7755 Result.getComplexIntImag() += RHS.getComplexIntImag(); 7756 } 7757 break; 7758 case BO_Sub: 7759 if (Result.isComplexFloat()) { 7760 Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(), 7761 APFloat::rmNearestTiesToEven); 7762 Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(), 7763 APFloat::rmNearestTiesToEven); 7764 } else { 7765 Result.getComplexIntReal() -= RHS.getComplexIntReal(); 7766 Result.getComplexIntImag() -= RHS.getComplexIntImag(); 7767 } 7768 break; 7769 case BO_Mul: 7770 if (Result.isComplexFloat()) { 7771 ComplexValue LHS = Result; 7772 APFloat &LHS_r = LHS.getComplexFloatReal(); 7773 APFloat &LHS_i = LHS.getComplexFloatImag(); 7774 APFloat &RHS_r = RHS.getComplexFloatReal(); 7775 APFloat &RHS_i = RHS.getComplexFloatImag(); 7776 7777 APFloat Tmp = LHS_r; 7778 Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven); 7779 Result.getComplexFloatReal() = Tmp; 7780 Tmp = LHS_i; 7781 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 7782 Result.getComplexFloatReal().subtract(Tmp, APFloat::rmNearestTiesToEven); 7783 7784 Tmp = LHS_r; 7785 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 7786 Result.getComplexFloatImag() = Tmp; 7787 Tmp = LHS_i; 7788 Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven); 7789 Result.getComplexFloatImag().add(Tmp, APFloat::rmNearestTiesToEven); 7790 } else { 7791 ComplexValue LHS = Result; 7792 Result.getComplexIntReal() = 7793 (LHS.getComplexIntReal() * RHS.getComplexIntReal() - 7794 LHS.getComplexIntImag() * RHS.getComplexIntImag()); 7795 Result.getComplexIntImag() = 7796 (LHS.getComplexIntReal() * RHS.getComplexIntImag() + 7797 LHS.getComplexIntImag() * RHS.getComplexIntReal()); 7798 } 7799 break; 7800 case BO_Div: 7801 if (Result.isComplexFloat()) { 7802 ComplexValue LHS = Result; 7803 APFloat &LHS_r = LHS.getComplexFloatReal(); 7804 APFloat &LHS_i = LHS.getComplexFloatImag(); 7805 APFloat &RHS_r = RHS.getComplexFloatReal(); 7806 APFloat &RHS_i = RHS.getComplexFloatImag(); 7807 APFloat &Res_r = Result.getComplexFloatReal(); 7808 APFloat &Res_i = Result.getComplexFloatImag(); 7809 7810 APFloat Den = RHS_r; 7811 Den.multiply(RHS_r, APFloat::rmNearestTiesToEven); 7812 APFloat Tmp = RHS_i; 7813 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 7814 Den.add(Tmp, APFloat::rmNearestTiesToEven); 7815 7816 Res_r = LHS_r; 7817 Res_r.multiply(RHS_r, APFloat::rmNearestTiesToEven); 7818 Tmp = LHS_i; 7819 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 7820 Res_r.add(Tmp, APFloat::rmNearestTiesToEven); 7821 Res_r.divide(Den, APFloat::rmNearestTiesToEven); 7822 7823 Res_i = LHS_i; 7824 Res_i.multiply(RHS_r, APFloat::rmNearestTiesToEven); 7825 Tmp = LHS_r; 7826 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 7827 Res_i.subtract(Tmp, APFloat::rmNearestTiesToEven); 7828 Res_i.divide(Den, APFloat::rmNearestTiesToEven); 7829 } else { 7830 if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0) 7831 return Error(E, diag::note_expr_divide_by_zero); 7832 7833 ComplexValue LHS = Result; 7834 APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() + 7835 RHS.getComplexIntImag() * RHS.getComplexIntImag(); 7836 Result.getComplexIntReal() = 7837 (LHS.getComplexIntReal() * RHS.getComplexIntReal() + 7838 LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den; 7839 Result.getComplexIntImag() = 7840 (LHS.getComplexIntImag() * RHS.getComplexIntReal() - 7841 LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den; 7842 } 7843 break; 7844 } 7845 7846 return true; 7847} 7848 7849bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 7850 // Get the operand value into 'Result'. 7851 if (!Visit(E->getSubExpr())) 7852 return false; 7853 7854 switch (E->getOpcode()) { 7855 default: 7856 return Error(E); 7857 case UO_Extension: 7858 return true; 7859 case UO_Plus: 7860 // The result is always just the subexpr. 7861 return true; 7862 case UO_Minus: 7863 if (Result.isComplexFloat()) { 7864 Result.getComplexFloatReal().changeSign(); 7865 Result.getComplexFloatImag().changeSign(); 7866 } 7867 else { 7868 Result.getComplexIntReal() = -Result.getComplexIntReal(); 7869 Result.getComplexIntImag() = -Result.getComplexIntImag(); 7870 } 7871 return true; 7872 case UO_Not: 7873 if (Result.isComplexFloat()) 7874 Result.getComplexFloatImag().changeSign(); 7875 else 7876 Result.getComplexIntImag() = -Result.getComplexIntImag(); 7877 return true; 7878 } 7879} 7880 7881bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 7882 if (E->getNumInits() == 2) { 7883 if (E->getType()->isComplexType()) { 7884 Result.makeComplexFloat(); 7885 if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info)) 7886 return false; 7887 if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info)) 7888 return false; 7889 } else { 7890 Result.makeComplexInt(); 7891 if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info)) 7892 return false; 7893 if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info)) 7894 return false; 7895 } 7896 return true; 7897 } 7898 return ExprEvaluatorBaseTy::VisitInitListExpr(E); 7899} 7900 7901//===----------------------------------------------------------------------===// 7902// Atomic expression evaluation, essentially just handling the NonAtomicToAtomic 7903// implicit conversion. 7904//===----------------------------------------------------------------------===// 7905 7906namespace { 7907class AtomicExprEvaluator : 7908 public ExprEvaluatorBase<AtomicExprEvaluator> { 7909 APValue &Result; 7910public: 7911 AtomicExprEvaluator(EvalInfo &Info, APValue &Result) 7912 : ExprEvaluatorBaseTy(Info), Result(Result) {} 7913 7914 bool Success(const APValue &V, const Expr *E) { 7915 Result = V; 7916 return true; 7917 } 7918 7919 bool ZeroInitialization(const Expr *E) { 7920 ImplicitValueInitExpr VIE( 7921 E->getType()->castAs<AtomicType>()->getValueType()); 7922 return Evaluate(Result, Info, &VIE); 7923 } 7924 7925 bool VisitCastExpr(const CastExpr *E) { 7926 switch (E->getCastKind()) { 7927 default: 7928 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7929 case CK_NonAtomicToAtomic: 7930 return Evaluate(Result, Info, E->getSubExpr()); 7931 } 7932 } 7933}; 7934} // end anonymous namespace 7935 7936static bool EvaluateAtomic(const Expr *E, APValue &Result, EvalInfo &Info) { 7937 assert(E->isRValue() && E->getType()->isAtomicType()); 7938 return AtomicExprEvaluator(Info, Result).Visit(E); 7939} 7940 7941//===----------------------------------------------------------------------===// 7942// Void expression evaluation, primarily for a cast to void on the LHS of a 7943// comma operator 7944//===----------------------------------------------------------------------===// 7945 7946namespace { 7947class VoidExprEvaluator 7948 : public ExprEvaluatorBase<VoidExprEvaluator> { 7949public: 7950 VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {} 7951 7952 bool Success(const APValue &V, const Expr *e) { return true; } 7953 7954 bool VisitCastExpr(const CastExpr *E) { 7955 switch (E->getCastKind()) { 7956 default: 7957 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7958 case CK_ToVoid: 7959 VisitIgnoredValue(E->getSubExpr()); 7960 return true; 7961 } 7962 } 7963 7964 bool VisitCallExpr(const CallExpr *E) { 7965 switch (E->getBuiltinCallee()) { 7966 default: 7967 return ExprEvaluatorBaseTy::VisitCallExpr(E); 7968 case Builtin::BI__assume: 7969 // The argument is not evaluated! 7970 return true; 7971 } 7972 } 7973}; 7974} // end anonymous namespace 7975 7976static bool EvaluateVoid(const Expr *E, EvalInfo &Info) { 7977 assert(E->isRValue() && E->getType()->isVoidType()); 7978 return VoidExprEvaluator(Info).Visit(E); 7979} 7980 7981//===----------------------------------------------------------------------===// 7982// Top level Expr::EvaluateAsRValue method. 7983//===----------------------------------------------------------------------===// 7984 7985static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) { 7986 // In C, function designators are not lvalues, but we evaluate them as if they 7987 // are. 7988 QualType T = E->getType(); 7989 if (E->isGLValue() || T->isFunctionType()) { 7990 LValue LV; 7991 if (!EvaluateLValue(E, LV, Info)) 7992 return false; 7993 LV.moveInto(Result); 7994 } else if (T->isVectorType()) { 7995 if (!EvaluateVector(E, Result, Info)) 7996 return false; 7997 } else if (T->isIntegralOrEnumerationType()) { 7998 if (!IntExprEvaluator(Info, Result).Visit(E)) 7999 return false; 8000 } else if (T->hasPointerRepresentation()) { 8001 LValue LV; 8002 if (!EvaluatePointer(E, LV, Info)) 8003 return false; 8004 LV.moveInto(Result); 8005 } else if (T->isRealFloatingType()) { 8006 llvm::APFloat F(0.0); 8007 if (!EvaluateFloat(E, F, Info)) 8008 return false; 8009 Result = APValue(F); 8010 } else if (T->isAnyComplexType()) { 8011 ComplexValue C; 8012 if (!EvaluateComplex(E, C, Info)) 8013 return false; 8014 C.moveInto(Result); 8015 } else if (T->isMemberPointerType()) { 8016 MemberPtr P; 8017 if (!EvaluateMemberPointer(E, P, Info)) 8018 return false; 8019 P.moveInto(Result); 8020 return true; 8021 } else if (T->isArrayType()) { 8022 LValue LV; 8023 LV.set(E, Info.CurrentCall->Index); 8024 APValue &Value = Info.CurrentCall->createTemporary(E, false); 8025 if (!EvaluateArray(E, LV, Value, Info)) 8026 return false; 8027 Result = Value; 8028 } else if (T->isRecordType()) { 8029 LValue LV; 8030 LV.set(E, Info.CurrentCall->Index); 8031 APValue &Value = Info.CurrentCall->createTemporary(E, false); 8032 if (!EvaluateRecord(E, LV, Value, Info)) 8033 return false; 8034 Result = Value; 8035 } else if (T->isVoidType()) { 8036 if (!Info.getLangOpts().CPlusPlus11) 8037 Info.CCEDiag(E, diag::note_constexpr_nonliteral) 8038 << E->getType(); 8039 if (!EvaluateVoid(E, Info)) 8040 return false; 8041 } else if (T->isAtomicType()) { 8042 if (!EvaluateAtomic(E, Result, Info)) 8043 return false; 8044 } else if (Info.getLangOpts().CPlusPlus11) { 8045 Info.Diag(E, diag::note_constexpr_nonliteral) << E->getType(); 8046 return false; 8047 } else { 8048 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 8049 return false; 8050 } 8051 8052 return true; 8053} 8054 8055/// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some 8056/// cases, the in-place evaluation is essential, since later initializers for 8057/// an object can indirectly refer to subobjects which were initialized earlier. 8058static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This, 8059 const Expr *E, bool AllowNonLiteralTypes) { 8060 assert(!E->isValueDependent()); 8061 8062 if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This)) 8063 return false; 8064 8065 if (E->isRValue()) { 8066 // Evaluate arrays and record types in-place, so that later initializers can 8067 // refer to earlier-initialized members of the object. 8068 if (E->getType()->isArrayType()) 8069 return EvaluateArray(E, This, Result, Info); 8070 else if (E->getType()->isRecordType()) 8071 return EvaluateRecord(E, This, Result, Info); 8072 } 8073 8074 // For any other type, in-place evaluation is unimportant. 8075 return Evaluate(Result, Info, E); 8076} 8077 8078/// EvaluateAsRValue - Try to evaluate this expression, performing an implicit 8079/// lvalue-to-rvalue cast if it is an lvalue. 8080static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) { 8081 if (E->getType().isNull()) 8082 return false; 8083 8084 if (!CheckLiteralType(Info, E)) 8085 return false; 8086 8087 if (!::Evaluate(Result, Info, E)) 8088 return false; 8089 8090 if (E->isGLValue()) { 8091 LValue LV; 8092 LV.setFrom(Info.Ctx, Result); 8093 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result)) 8094 return false; 8095 } 8096 8097 // Check this core constant expression is a constant expression. 8098 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result); 8099} 8100 8101static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result, 8102 const ASTContext &Ctx, bool &IsConst) { 8103 // Fast-path evaluations of integer literals, since we sometimes see files 8104 // containing vast quantities of these. 8105 if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) { 8106 Result.Val = APValue(APSInt(L->getValue(), 8107 L->getType()->isUnsignedIntegerType())); 8108 IsConst = true; 8109 return true; 8110 } 8111 8112 // This case should be rare, but we need to check it before we check on 8113 // the type below. 8114 if (Exp->getType().isNull()) { 8115 IsConst = false; 8116 return true; 8117 } 8118 8119 // FIXME: Evaluating values of large array and record types can cause 8120 // performance problems. Only do so in C++11 for now. 8121 if (Exp->isRValue() && (Exp->getType()->isArrayType() || 8122 Exp->getType()->isRecordType()) && 8123 !Ctx.getLangOpts().CPlusPlus11) { 8124 IsConst = false; 8125 return true; 8126 } 8127 return false; 8128} 8129 8130 8131/// EvaluateAsRValue - Return true if this is a constant which we can fold using 8132/// any crazy technique (that has nothing to do with language standards) that 8133/// we want to. If this function returns true, it returns the folded constant 8134/// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion 8135/// will be applied to the result. 8136bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx) const { 8137 bool IsConst; 8138 if (FastEvaluateAsRValue(this, Result, Ctx, IsConst)) 8139 return IsConst; 8140 8141 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); 8142 return ::EvaluateAsRValue(Info, this, Result.Val); 8143} 8144 8145bool Expr::EvaluateAsBooleanCondition(bool &Result, 8146 const ASTContext &Ctx) const { 8147 EvalResult Scratch; 8148 return EvaluateAsRValue(Scratch, Ctx) && 8149 HandleConversionToBool(Scratch.Val, Result); 8150} 8151 8152bool Expr::EvaluateAsInt(APSInt &Result, const ASTContext &Ctx, 8153 SideEffectsKind AllowSideEffects) const { 8154 if (!getType()->isIntegralOrEnumerationType()) 8155 return false; 8156 8157 EvalResult ExprResult; 8158 if (!EvaluateAsRValue(ExprResult, Ctx) || !ExprResult.Val.isInt() || 8159 (!AllowSideEffects && ExprResult.HasSideEffects)) 8160 return false; 8161 8162 Result = ExprResult.Val.getInt(); 8163 return true; 8164} 8165 8166bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx) const { 8167 EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold); 8168 8169 LValue LV; 8170 if (!EvaluateLValue(this, LV, Info) || Result.HasSideEffects || 8171 !CheckLValueConstantExpression(Info, getExprLoc(), 8172 Ctx.getLValueReferenceType(getType()), LV)) 8173 return false; 8174 8175 LV.moveInto(Result.Val); 8176 return true; 8177} 8178 8179bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx, 8180 const VarDecl *VD, 8181 SmallVectorImpl<PartialDiagnosticAt> &Notes) const { 8182 // FIXME: Evaluating initializers for large array and record types can cause 8183 // performance problems. Only do so in C++11 for now. 8184 if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) && 8185 !Ctx.getLangOpts().CPlusPlus11) 8186 return false; 8187 8188 Expr::EvalStatus EStatus; 8189 EStatus.Diag = &Notes; 8190 8191 EvalInfo InitInfo(Ctx, EStatus, EvalInfo::EM_ConstantFold); 8192 InitInfo.setEvaluatingDecl(VD, Value); 8193 8194 LValue LVal; 8195 LVal.set(VD); 8196 8197 // C++11 [basic.start.init]p2: 8198 // Variables with static storage duration or thread storage duration shall be 8199 // zero-initialized before any other initialization takes place. 8200 // This behavior is not present in C. 8201 if (Ctx.getLangOpts().CPlusPlus && !VD->hasLocalStorage() && 8202 !VD->getType()->isReferenceType()) { 8203 ImplicitValueInitExpr VIE(VD->getType()); 8204 if (!EvaluateInPlace(Value, InitInfo, LVal, &VIE, 8205 /*AllowNonLiteralTypes=*/true)) 8206 return false; 8207 } 8208 8209 if (!EvaluateInPlace(Value, InitInfo, LVal, this, 8210 /*AllowNonLiteralTypes=*/true) || 8211 EStatus.HasSideEffects) 8212 return false; 8213 8214 return CheckConstantExpression(InitInfo, VD->getLocation(), VD->getType(), 8215 Value); 8216} 8217 8218/// isEvaluatable - Call EvaluateAsRValue to see if this expression can be 8219/// constant folded, but discard the result. 8220bool Expr::isEvaluatable(const ASTContext &Ctx) const { 8221 EvalResult Result; 8222 return EvaluateAsRValue(Result, Ctx) && !Result.HasSideEffects; 8223} 8224 8225APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx, 8226 SmallVectorImpl<PartialDiagnosticAt> *Diag) const { 8227 EvalResult EvalResult; 8228 EvalResult.Diag = Diag; 8229 bool Result = EvaluateAsRValue(EvalResult, Ctx); 8230 (void)Result; 8231 assert(Result && "Could not evaluate expression"); 8232 assert(EvalResult.Val.isInt() && "Expression did not evaluate to integer"); 8233 8234 return EvalResult.Val.getInt(); 8235} 8236 8237void Expr::EvaluateForOverflow(const ASTContext &Ctx) const { 8238 bool IsConst; 8239 EvalResult EvalResult; 8240 if (!FastEvaluateAsRValue(this, EvalResult, Ctx, IsConst)) { 8241 EvalInfo Info(Ctx, EvalResult, EvalInfo::EM_EvaluateForOverflow); 8242 (void)::EvaluateAsRValue(Info, this, EvalResult.Val); 8243 } 8244} 8245 8246bool Expr::EvalResult::isGlobalLValue() const { 8247 assert(Val.isLValue()); 8248 return IsGlobalLValue(Val.getLValueBase()); 8249} 8250 8251 8252/// isIntegerConstantExpr - this recursive routine will test if an expression is 8253/// an integer constant expression. 8254 8255/// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero, 8256/// comma, etc 8257 8258// CheckICE - This function does the fundamental ICE checking: the returned 8259// ICEDiag contains an ICEKind indicating whether the expression is an ICE, 8260// and a (possibly null) SourceLocation indicating the location of the problem. 8261// 8262// Note that to reduce code duplication, this helper does no evaluation 8263// itself; the caller checks whether the expression is evaluatable, and 8264// in the rare cases where CheckICE actually cares about the evaluated 8265// value, it calls into Evalute. 8266 8267namespace { 8268 8269enum ICEKind { 8270 /// This expression is an ICE. 8271 IK_ICE, 8272 /// This expression is not an ICE, but if it isn't evaluated, it's 8273 /// a legal subexpression for an ICE. This return value is used to handle 8274 /// the comma operator in C99 mode, and non-constant subexpressions. 8275 IK_ICEIfUnevaluated, 8276 /// This expression is not an ICE, and is not a legal subexpression for one. 8277 IK_NotICE 8278}; 8279 8280struct ICEDiag { 8281 ICEKind Kind; 8282 SourceLocation Loc; 8283 8284 ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {} 8285}; 8286 8287} 8288 8289static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); } 8290 8291static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; } 8292 8293static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) { 8294 Expr::EvalResult EVResult; 8295 if (!E->EvaluateAsRValue(EVResult, Ctx) || EVResult.HasSideEffects || 8296 !EVResult.Val.isInt()) 8297 return ICEDiag(IK_NotICE, E->getLocStart()); 8298 8299 return NoDiag(); 8300} 8301 8302static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) { 8303 assert(!E->isValueDependent() && "Should not see value dependent exprs!"); 8304 if (!E->getType()->isIntegralOrEnumerationType()) 8305 return ICEDiag(IK_NotICE, E->getLocStart()); 8306 8307 switch (E->getStmtClass()) { 8308#define ABSTRACT_STMT(Node) 8309#define STMT(Node, Base) case Expr::Node##Class: 8310#define EXPR(Node, Base) 8311#include "clang/AST/StmtNodes.inc" 8312 case Expr::PredefinedExprClass: 8313 case Expr::FloatingLiteralClass: 8314 case Expr::ImaginaryLiteralClass: 8315 case Expr::StringLiteralClass: 8316 case Expr::ArraySubscriptExprClass: 8317 case Expr::MemberExprClass: 8318 case Expr::CompoundAssignOperatorClass: 8319 case Expr::CompoundLiteralExprClass: 8320 case Expr::ExtVectorElementExprClass: 8321 case Expr::DesignatedInitExprClass: 8322 case Expr::ImplicitValueInitExprClass: 8323 case Expr::ParenListExprClass: 8324 case Expr::VAArgExprClass: 8325 case Expr::AddrLabelExprClass: 8326 case Expr::StmtExprClass: 8327 case Expr::CXXMemberCallExprClass: 8328 case Expr::CUDAKernelCallExprClass: 8329 case Expr::CXXDynamicCastExprClass: 8330 case Expr::CXXTypeidExprClass: 8331 case Expr::CXXUuidofExprClass: 8332 case Expr::MSPropertyRefExprClass: 8333 case Expr::CXXNullPtrLiteralExprClass: 8334 case Expr::UserDefinedLiteralClass: 8335 case Expr::CXXThisExprClass: 8336 case Expr::CXXThrowExprClass: 8337 case Expr::CXXNewExprClass: 8338 case Expr::CXXDeleteExprClass: 8339 case Expr::CXXPseudoDestructorExprClass: 8340 case Expr::UnresolvedLookupExprClass: 8341 case Expr::DependentScopeDeclRefExprClass: 8342 case Expr::CXXConstructExprClass: 8343 case Expr::CXXStdInitializerListExprClass: 8344 case Expr::CXXBindTemporaryExprClass: 8345 case Expr::ExprWithCleanupsClass: 8346 case Expr::CXXTemporaryObjectExprClass: 8347 case Expr::CXXUnresolvedConstructExprClass: 8348 case Expr::CXXDependentScopeMemberExprClass: 8349 case Expr::UnresolvedMemberExprClass: 8350 case Expr::ObjCStringLiteralClass: 8351 case Expr::ObjCBoxedExprClass: 8352 case Expr::ObjCArrayLiteralClass: 8353 case Expr::ObjCDictionaryLiteralClass: 8354 case Expr::ObjCEncodeExprClass: 8355 case Expr::ObjCMessageExprClass: 8356 case Expr::ObjCSelectorExprClass: 8357 case Expr::ObjCProtocolExprClass: 8358 case Expr::ObjCIvarRefExprClass: 8359 case Expr::ObjCPropertyRefExprClass: 8360 case Expr::ObjCSubscriptRefExprClass: 8361 case Expr::ObjCIsaExprClass: 8362 case Expr::ShuffleVectorExprClass: 8363 case Expr::ConvertVectorExprClass: 8364 case Expr::BlockExprClass: 8365 case Expr::NoStmtClass: 8366 case Expr::OpaqueValueExprClass: 8367 case Expr::PackExpansionExprClass: 8368 case Expr::SubstNonTypeTemplateParmPackExprClass: 8369 case Expr::FunctionParmPackExprClass: 8370 case Expr::AsTypeExprClass: 8371 case Expr::ObjCIndirectCopyRestoreExprClass: 8372 case Expr::MaterializeTemporaryExprClass: 8373 case Expr::PseudoObjectExprClass: 8374 case Expr::AtomicExprClass: 8375 case Expr::LambdaExprClass: 8376 return ICEDiag(IK_NotICE, E->getLocStart()); 8377 8378 case Expr::InitListExprClass: { 8379 // C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the 8380 // form "T x = { a };" is equivalent to "T x = a;". 8381 // Unless we're initializing a reference, T is a scalar as it is known to be 8382 // of integral or enumeration type. 8383 if (E->isRValue()) 8384 if (cast<InitListExpr>(E)->getNumInits() == 1) 8385 return CheckICE(cast<InitListExpr>(E)->getInit(0), Ctx); 8386 return ICEDiag(IK_NotICE, E->getLocStart()); 8387 } 8388 8389 case Expr::SizeOfPackExprClass: 8390 case Expr::GNUNullExprClass: 8391 // GCC considers the GNU __null value to be an integral constant expression. 8392 return NoDiag(); 8393 8394 case Expr::SubstNonTypeTemplateParmExprClass: 8395 return 8396 CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx); 8397 8398 case Expr::ParenExprClass: 8399 return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx); 8400 case Expr::GenericSelectionExprClass: 8401 return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx); 8402 case Expr::IntegerLiteralClass: 8403 case Expr::CharacterLiteralClass: 8404 case Expr::ObjCBoolLiteralExprClass: 8405 case Expr::CXXBoolLiteralExprClass: 8406 case Expr::CXXScalarValueInitExprClass: 8407 case Expr::TypeTraitExprClass: 8408 case Expr::ArrayTypeTraitExprClass: 8409 case Expr::ExpressionTraitExprClass: 8410 case Expr::CXXNoexceptExprClass: 8411 return NoDiag(); 8412 case Expr::CallExprClass: 8413 case Expr::CXXOperatorCallExprClass: { 8414 // C99 6.6/3 allows function calls within unevaluated subexpressions of 8415 // constant expressions, but they can never be ICEs because an ICE cannot 8416 // contain an operand of (pointer to) function type. 8417 const CallExpr *CE = cast<CallExpr>(E); 8418 if (CE->getBuiltinCallee()) 8419 return CheckEvalInICE(E, Ctx); 8420 return ICEDiag(IK_NotICE, E->getLocStart()); 8421 } 8422 case Expr::DeclRefExprClass: { 8423 if (isa<EnumConstantDecl>(cast<DeclRefExpr>(E)->getDecl())) 8424 return NoDiag(); 8425 const ValueDecl *D = dyn_cast<ValueDecl>(cast<DeclRefExpr>(E)->getDecl()); 8426 if (Ctx.getLangOpts().CPlusPlus && 8427 D && IsConstNonVolatile(D->getType())) { 8428 // Parameter variables are never constants. Without this check, 8429 // getAnyInitializer() can find a default argument, which leads 8430 // to chaos. 8431 if (isa<ParmVarDecl>(D)) 8432 return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); 8433 8434 // C++ 7.1.5.1p2 8435 // A variable of non-volatile const-qualified integral or enumeration 8436 // type initialized by an ICE can be used in ICEs. 8437 if (const VarDecl *Dcl = dyn_cast<VarDecl>(D)) { 8438 if (!Dcl->getType()->isIntegralOrEnumerationType()) 8439 return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); 8440 8441 const VarDecl *VD; 8442 // Look for a declaration of this variable that has an initializer, and 8443 // check whether it is an ICE. 8444 if (Dcl->getAnyInitializer(VD) && VD->checkInitIsICE()) 8445 return NoDiag(); 8446 else 8447 return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); 8448 } 8449 } 8450 return ICEDiag(IK_NotICE, E->getLocStart()); 8451 } 8452 case Expr::UnaryOperatorClass: { 8453 const UnaryOperator *Exp = cast<UnaryOperator>(E); 8454 switch (Exp->getOpcode()) { 8455 case UO_PostInc: 8456 case UO_PostDec: 8457 case UO_PreInc: 8458 case UO_PreDec: 8459 case UO_AddrOf: 8460 case UO_Deref: 8461 // C99 6.6/3 allows increment and decrement within unevaluated 8462 // subexpressions of constant expressions, but they can never be ICEs 8463 // because an ICE cannot contain an lvalue operand. 8464 return ICEDiag(IK_NotICE, E->getLocStart()); 8465 case UO_Extension: 8466 case UO_LNot: 8467 case UO_Plus: 8468 case UO_Minus: 8469 case UO_Not: 8470 case UO_Real: 8471 case UO_Imag: 8472 return CheckICE(Exp->getSubExpr(), Ctx); 8473 } 8474 8475 // OffsetOf falls through here. 8476 } 8477 case Expr::OffsetOfExprClass: { 8478 // Note that per C99, offsetof must be an ICE. And AFAIK, using 8479 // EvaluateAsRValue matches the proposed gcc behavior for cases like 8480 // "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect 8481 // compliance: we should warn earlier for offsetof expressions with 8482 // array subscripts that aren't ICEs, and if the array subscripts 8483 // are ICEs, the value of the offsetof must be an integer constant. 8484 return CheckEvalInICE(E, Ctx); 8485 } 8486 case Expr::UnaryExprOrTypeTraitExprClass: { 8487 const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E); 8488 if ((Exp->getKind() == UETT_SizeOf) && 8489 Exp->getTypeOfArgument()->isVariableArrayType()) 8490 return ICEDiag(IK_NotICE, E->getLocStart()); 8491 return NoDiag(); 8492 } 8493 case Expr::BinaryOperatorClass: { 8494 const BinaryOperator *Exp = cast<BinaryOperator>(E); 8495 switch (Exp->getOpcode()) { 8496 case BO_PtrMemD: 8497 case BO_PtrMemI: 8498 case BO_Assign: 8499 case BO_MulAssign: 8500 case BO_DivAssign: 8501 case BO_RemAssign: 8502 case BO_AddAssign: 8503 case BO_SubAssign: 8504 case BO_ShlAssign: 8505 case BO_ShrAssign: 8506 case BO_AndAssign: 8507 case BO_XorAssign: 8508 case BO_OrAssign: 8509 // C99 6.6/3 allows assignments within unevaluated subexpressions of 8510 // constant expressions, but they can never be ICEs because an ICE cannot 8511 // contain an lvalue operand. 8512 return ICEDiag(IK_NotICE, E->getLocStart()); 8513 8514 case BO_Mul: 8515 case BO_Div: 8516 case BO_Rem: 8517 case BO_Add: 8518 case BO_Sub: 8519 case BO_Shl: 8520 case BO_Shr: 8521 case BO_LT: 8522 case BO_GT: 8523 case BO_LE: 8524 case BO_GE: 8525 case BO_EQ: 8526 case BO_NE: 8527 case BO_And: 8528 case BO_Xor: 8529 case BO_Or: 8530 case BO_Comma: { 8531 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); 8532 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); 8533 if (Exp->getOpcode() == BO_Div || 8534 Exp->getOpcode() == BO_Rem) { 8535 // EvaluateAsRValue gives an error for undefined Div/Rem, so make sure 8536 // we don't evaluate one. 8537 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) { 8538 llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx); 8539 if (REval == 0) 8540 return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); 8541 if (REval.isSigned() && REval.isAllOnesValue()) { 8542 llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx); 8543 if (LEval.isMinSignedValue()) 8544 return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); 8545 } 8546 } 8547 } 8548 if (Exp->getOpcode() == BO_Comma) { 8549 if (Ctx.getLangOpts().C99) { 8550 // C99 6.6p3 introduces a strange edge case: comma can be in an ICE 8551 // if it isn't evaluated. 8552 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) 8553 return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); 8554 } else { 8555 // In both C89 and C++, commas in ICEs are illegal. 8556 return ICEDiag(IK_NotICE, E->getLocStart()); 8557 } 8558 } 8559 return Worst(LHSResult, RHSResult); 8560 } 8561 case BO_LAnd: 8562 case BO_LOr: { 8563 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); 8564 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); 8565 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) { 8566 // Rare case where the RHS has a comma "side-effect"; we need 8567 // to actually check the condition to see whether the side 8568 // with the comma is evaluated. 8569 if ((Exp->getOpcode() == BO_LAnd) != 8570 (Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0)) 8571 return RHSResult; 8572 return NoDiag(); 8573 } 8574 8575 return Worst(LHSResult, RHSResult); 8576 } 8577 } 8578 } 8579 case Expr::ImplicitCastExprClass: 8580 case Expr::CStyleCastExprClass: 8581 case Expr::CXXFunctionalCastExprClass: 8582 case Expr::CXXStaticCastExprClass: 8583 case Expr::CXXReinterpretCastExprClass: 8584 case Expr::CXXConstCastExprClass: 8585 case Expr::ObjCBridgedCastExprClass: { 8586 const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr(); 8587 if (isa<ExplicitCastExpr>(E)) { 8588 if (const FloatingLiteral *FL 8589 = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) { 8590 unsigned DestWidth = Ctx.getIntWidth(E->getType()); 8591 bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType(); 8592 APSInt IgnoredVal(DestWidth, !DestSigned); 8593 bool Ignored; 8594 // If the value does not fit in the destination type, the behavior is 8595 // undefined, so we are not required to treat it as a constant 8596 // expression. 8597 if (FL->getValue().convertToInteger(IgnoredVal, 8598 llvm::APFloat::rmTowardZero, 8599 &Ignored) & APFloat::opInvalidOp) 8600 return ICEDiag(IK_NotICE, E->getLocStart()); 8601 return NoDiag(); 8602 } 8603 } 8604 switch (cast<CastExpr>(E)->getCastKind()) { 8605 case CK_LValueToRValue: 8606 case CK_AtomicToNonAtomic: 8607 case CK_NonAtomicToAtomic: 8608 case CK_NoOp: 8609 case CK_IntegralToBoolean: 8610 case CK_IntegralCast: 8611 return CheckICE(SubExpr, Ctx); 8612 default: 8613 return ICEDiag(IK_NotICE, E->getLocStart()); 8614 } 8615 } 8616 case Expr::BinaryConditionalOperatorClass: { 8617 const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E); 8618 ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx); 8619 if (CommonResult.Kind == IK_NotICE) return CommonResult; 8620 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); 8621 if (FalseResult.Kind == IK_NotICE) return FalseResult; 8622 if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult; 8623 if (FalseResult.Kind == IK_ICEIfUnevaluated && 8624 Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag(); 8625 return FalseResult; 8626 } 8627 case Expr::ConditionalOperatorClass: { 8628 const ConditionalOperator *Exp = cast<ConditionalOperator>(E); 8629 // If the condition (ignoring parens) is a __builtin_constant_p call, 8630 // then only the true side is actually considered in an integer constant 8631 // expression, and it is fully evaluated. This is an important GNU 8632 // extension. See GCC PR38377 for discussion. 8633 if (const CallExpr *CallCE 8634 = dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts())) 8635 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) 8636 return CheckEvalInICE(E, Ctx); 8637 ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx); 8638 if (CondResult.Kind == IK_NotICE) 8639 return CondResult; 8640 8641 ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx); 8642 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); 8643 8644 if (TrueResult.Kind == IK_NotICE) 8645 return TrueResult; 8646 if (FalseResult.Kind == IK_NotICE) 8647 return FalseResult; 8648 if (CondResult.Kind == IK_ICEIfUnevaluated) 8649 return CondResult; 8650 if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE) 8651 return NoDiag(); 8652 // Rare case where the diagnostics depend on which side is evaluated 8653 // Note that if we get here, CondResult is 0, and at least one of 8654 // TrueResult and FalseResult is non-zero. 8655 if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0) 8656 return FalseResult; 8657 return TrueResult; 8658 } 8659 case Expr::CXXDefaultArgExprClass: 8660 return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx); 8661 case Expr::CXXDefaultInitExprClass: 8662 return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx); 8663 case Expr::ChooseExprClass: { 8664 return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx); 8665 } 8666 } 8667 8668 llvm_unreachable("Invalid StmtClass!"); 8669} 8670 8671/// Evaluate an expression as a C++11 integral constant expression. 8672static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx, 8673 const Expr *E, 8674 llvm::APSInt *Value, 8675 SourceLocation *Loc) { 8676 if (!E->getType()->isIntegralOrEnumerationType()) { 8677 if (Loc) *Loc = E->getExprLoc(); 8678 return false; 8679 } 8680 8681 APValue Result; 8682 if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc)) 8683 return false; 8684 8685 assert(Result.isInt() && "pointer cast to int is not an ICE"); 8686 if (Value) *Value = Result.getInt(); 8687 return true; 8688} 8689 8690bool Expr::isIntegerConstantExpr(const ASTContext &Ctx, 8691 SourceLocation *Loc) const { 8692 if (Ctx.getLangOpts().CPlusPlus11) 8693 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, nullptr, Loc); 8694 8695 ICEDiag D = CheckICE(this, Ctx); 8696 if (D.Kind != IK_ICE) { 8697 if (Loc) *Loc = D.Loc; 8698 return false; 8699 } 8700 return true; 8701} 8702 8703bool Expr::isIntegerConstantExpr(llvm::APSInt &Value, const ASTContext &Ctx, 8704 SourceLocation *Loc, bool isEvaluated) const { 8705 if (Ctx.getLangOpts().CPlusPlus11) 8706 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc); 8707 8708 if (!isIntegerConstantExpr(Ctx, Loc)) 8709 return false; 8710 if (!EvaluateAsInt(Value, Ctx)) 8711 llvm_unreachable("ICE cannot be evaluated!"); 8712 return true; 8713} 8714 8715bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const { 8716 return CheckICE(this, Ctx).Kind == IK_ICE; 8717} 8718 8719bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result, 8720 SourceLocation *Loc) const { 8721 // We support this checking in C++98 mode in order to diagnose compatibility 8722 // issues. 8723 assert(Ctx.getLangOpts().CPlusPlus); 8724 8725 // Build evaluation settings. 8726 Expr::EvalStatus Status; 8727 SmallVector<PartialDiagnosticAt, 8> Diags; 8728 Status.Diag = &Diags; 8729 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression); 8730 8731 APValue Scratch; 8732 bool IsConstExpr = ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch); 8733 8734 if (!Diags.empty()) { 8735 IsConstExpr = false; 8736 if (Loc) *Loc = Diags[0].first; 8737 } else if (!IsConstExpr) { 8738 // FIXME: This shouldn't happen. 8739 if (Loc) *Loc = getExprLoc(); 8740 } 8741 8742 return IsConstExpr; 8743} 8744 8745bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx, 8746 const FunctionDecl *Callee, 8747 ArrayRef<const Expr*> Args) const { 8748 Expr::EvalStatus Status; 8749 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated); 8750 8751 ArgVector ArgValues(Args.size()); 8752 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end(); 8753 I != E; ++I) { 8754 if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) 8755 // If evaluation fails, throw away the argument entirely. 8756 ArgValues[I - Args.begin()] = APValue(); 8757 if (Info.EvalStatus.HasSideEffects) 8758 return false; 8759 } 8760 8761 // Build fake call to Callee. 8762 CallStackFrame Frame(Info, Callee->getLocation(), Callee, /*This*/nullptr, 8763 ArgValues.data()); 8764 return Evaluate(Value, Info, this) && !Info.EvalStatus.HasSideEffects; 8765} 8766 8767bool Expr::isPotentialConstantExpr(const FunctionDecl *FD, 8768 SmallVectorImpl< 8769 PartialDiagnosticAt> &Diags) { 8770 // FIXME: It would be useful to check constexpr function templates, but at the 8771 // moment the constant expression evaluator cannot cope with the non-rigorous 8772 // ASTs which we build for dependent expressions. 8773 if (FD->isDependentContext()) 8774 return true; 8775 8776 Expr::EvalStatus Status; 8777 Status.Diag = &Diags; 8778 8779 EvalInfo Info(FD->getASTContext(), Status, 8780 EvalInfo::EM_PotentialConstantExpression); 8781 8782 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); 8783 const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr; 8784 8785 // Fabricate an arbitrary expression on the stack and pretend that it 8786 // is a temporary being used as the 'this' pointer. 8787 LValue This; 8788 ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy); 8789 This.set(&VIE, Info.CurrentCall->Index); 8790 8791 ArrayRef<const Expr*> Args; 8792 8793 SourceLocation Loc = FD->getLocation(); 8794 8795 APValue Scratch; 8796 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) { 8797 // Evaluate the call as a constant initializer, to allow the construction 8798 // of objects of non-literal types. 8799 Info.setEvaluatingDecl(This.getLValueBase(), Scratch); 8800 HandleConstructorCall(Loc, This, Args, CD, Info, Scratch); 8801 } else 8802 HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : nullptr, 8803 Args, FD->getBody(), Info, Scratch); 8804 8805 return Diags.empty(); 8806} 8807 8808bool Expr::isPotentialConstantExprUnevaluated(Expr *E, 8809 const FunctionDecl *FD, 8810 SmallVectorImpl< 8811 PartialDiagnosticAt> &Diags) { 8812 Expr::EvalStatus Status; 8813 Status.Diag = &Diags; 8814 8815 EvalInfo Info(FD->getASTContext(), Status, 8816 EvalInfo::EM_PotentialConstantExpressionUnevaluated); 8817 8818 // Fabricate a call stack frame to give the arguments a plausible cover story. 8819 ArrayRef<const Expr*> Args; 8820 ArgVector ArgValues(0); 8821 bool Success = EvaluateArgs(Args, ArgValues, Info); 8822 (void)Success; 8823 assert(Success && 8824 "Failed to set up arguments for potential constant evaluation"); 8825 CallStackFrame Frame(Info, SourceLocation(), FD, nullptr, ArgValues.data()); 8826 8827 APValue ResultScratch; 8828 Evaluate(ResultScratch, Info, E); 8829 return Diags.empty(); 8830} 8831