ExprConstant.cpp revision 263508
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() ? 0 : &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 = 0) : Diag(Diag) {} 351 352 template<typename T> 353 OptionalDiagnostic &operator<<(const T &v) { 354 if (Diag) 355 *Diag << v; 356 return *this; 357 } 358 359 OptionalDiagnostic &operator<<(const APSInt &I) { 360 if (Diag) { 361 SmallVector<char, 32> Buffer; 362 I.toString(Buffer); 363 *Diag << StringRef(Buffer.data(), Buffer.size()); 364 } 365 return *this; 366 } 367 368 OptionalDiagnostic &operator<<(const APFloat &F) { 369 if (Diag) { 370 // FIXME: Force the precision of the source value down so we don't 371 // print digits which are usually useless (we don't really care here if 372 // we truncate a digit by accident in edge cases). Ideally, 373 // APFloat::toString would automatically print the shortest 374 // representation which rounds to the correct value, but it's a bit 375 // tricky to implement. 376 unsigned precision = 377 llvm::APFloat::semanticsPrecision(F.getSemantics()); 378 precision = (precision * 59 + 195) / 196; 379 SmallVector<char, 32> Buffer; 380 F.toString(Buffer, precision); 381 *Diag << StringRef(Buffer.data(), Buffer.size()); 382 } 383 return *this; 384 } 385 }; 386 387 /// A cleanup, and a flag indicating whether it is lifetime-extended. 388 class Cleanup { 389 llvm::PointerIntPair<APValue*, 1, bool> Value; 390 391 public: 392 Cleanup(APValue *Val, bool IsLifetimeExtended) 393 : Value(Val, IsLifetimeExtended) {} 394 395 bool isLifetimeExtended() const { return Value.getInt(); } 396 void endLifetime() { 397 *Value.getPointer() = APValue(); 398 } 399 }; 400 401 /// EvalInfo - This is a private struct used by the evaluator to capture 402 /// information about a subexpression as it is folded. It retains information 403 /// about the AST context, but also maintains information about the folded 404 /// expression. 405 /// 406 /// If an expression could be evaluated, it is still possible it is not a C 407 /// "integer constant expression" or constant expression. If not, this struct 408 /// captures information about how and why not. 409 /// 410 /// One bit of information passed *into* the request for constant folding 411 /// indicates whether the subexpression is "evaluated" or not according to C 412 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can 413 /// evaluate the expression regardless of what the RHS is, but C only allows 414 /// certain things in certain situations. 415 struct EvalInfo { 416 ASTContext &Ctx; 417 418 /// EvalStatus - Contains information about the evaluation. 419 Expr::EvalStatus &EvalStatus; 420 421 /// CurrentCall - The top of the constexpr call stack. 422 CallStackFrame *CurrentCall; 423 424 /// CallStackDepth - The number of calls in the call stack right now. 425 unsigned CallStackDepth; 426 427 /// NextCallIndex - The next call index to assign. 428 unsigned NextCallIndex; 429 430 /// StepsLeft - The remaining number of evaluation steps we're permitted 431 /// to perform. This is essentially a limit for the number of statements 432 /// we will evaluate. 433 unsigned StepsLeft; 434 435 /// BottomFrame - The frame in which evaluation started. This must be 436 /// initialized after CurrentCall and CallStackDepth. 437 CallStackFrame BottomFrame; 438 439 /// A stack of values whose lifetimes end at the end of some surrounding 440 /// evaluation frame. 441 llvm::SmallVector<Cleanup, 16> CleanupStack; 442 443 /// EvaluatingDecl - This is the declaration whose initializer is being 444 /// evaluated, if any. 445 APValue::LValueBase EvaluatingDecl; 446 447 /// EvaluatingDeclValue - This is the value being constructed for the 448 /// declaration whose initializer is being evaluated, if any. 449 APValue *EvaluatingDeclValue; 450 451 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further 452 /// notes attached to it will also be stored, otherwise they will not be. 453 bool HasActiveDiagnostic; 454 455 enum EvaluationMode { 456 /// Evaluate as a constant expression. Stop if we find that the expression 457 /// is not a constant expression. 458 EM_ConstantExpression, 459 460 /// Evaluate as a potential constant expression. Keep going if we hit a 461 /// construct that we can't evaluate yet (because we don't yet know the 462 /// value of something) but stop if we hit something that could never be 463 /// a constant expression. 464 EM_PotentialConstantExpression, 465 466 /// Fold the expression to a constant. Stop if we hit a side-effect that 467 /// we can't model. 468 EM_ConstantFold, 469 470 /// Evaluate the expression looking for integer overflow and similar 471 /// issues. Don't worry about side-effects, and try to visit all 472 /// subexpressions. 473 EM_EvaluateForOverflow, 474 475 /// Evaluate in any way we know how. Don't worry about side-effects that 476 /// can't be modeled. 477 EM_IgnoreSideEffects 478 } EvalMode; 479 480 /// Are we checking whether the expression is a potential constant 481 /// expression? 482 bool checkingPotentialConstantExpression() const { 483 return EvalMode == EM_PotentialConstantExpression; 484 } 485 486 /// Are we checking an expression for overflow? 487 // FIXME: We should check for any kind of undefined or suspicious behavior 488 // in such constructs, not just overflow. 489 bool checkingForOverflow() { return EvalMode == EM_EvaluateForOverflow; } 490 491 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode) 492 : Ctx(const_cast<ASTContext&>(C)), EvalStatus(S), CurrentCall(0), 493 CallStackDepth(0), NextCallIndex(1), 494 StepsLeft(getLangOpts().ConstexprStepLimit), 495 BottomFrame(*this, SourceLocation(), 0, 0, 0), 496 EvaluatingDecl((const ValueDecl*)0), EvaluatingDeclValue(0), 497 HasActiveDiagnostic(false), EvalMode(Mode) {} 498 499 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) { 500 EvaluatingDecl = Base; 501 EvaluatingDeclValue = &Value; 502 } 503 504 const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); } 505 506 bool CheckCallLimit(SourceLocation Loc) { 507 // Don't perform any constexpr calls (other than the call we're checking) 508 // when checking a potential constant expression. 509 if (checkingPotentialConstantExpression() && CallStackDepth > 1) 510 return false; 511 if (NextCallIndex == 0) { 512 // NextCallIndex has wrapped around. 513 Diag(Loc, diag::note_constexpr_call_limit_exceeded); 514 return false; 515 } 516 if (CallStackDepth <= getLangOpts().ConstexprCallDepth) 517 return true; 518 Diag(Loc, diag::note_constexpr_depth_limit_exceeded) 519 << getLangOpts().ConstexprCallDepth; 520 return false; 521 } 522 523 CallStackFrame *getCallFrame(unsigned CallIndex) { 524 assert(CallIndex && "no call index in getCallFrame"); 525 // We will eventually hit BottomFrame, which has Index 1, so Frame can't 526 // be null in this loop. 527 CallStackFrame *Frame = CurrentCall; 528 while (Frame->Index > CallIndex) 529 Frame = Frame->Caller; 530 return (Frame->Index == CallIndex) ? Frame : 0; 531 } 532 533 bool nextStep(const Stmt *S) { 534 if (!StepsLeft) { 535 Diag(S->getLocStart(), diag::note_constexpr_step_limit_exceeded); 536 return false; 537 } 538 --StepsLeft; 539 return true; 540 } 541 542 private: 543 /// Add a diagnostic to the diagnostics list. 544 PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId) { 545 PartialDiagnostic PD(DiagId, Ctx.getDiagAllocator()); 546 EvalStatus.Diag->push_back(std::make_pair(Loc, PD)); 547 return EvalStatus.Diag->back().second; 548 } 549 550 /// Add notes containing a call stack to the current point of evaluation. 551 void addCallStack(unsigned Limit); 552 553 public: 554 /// Diagnose that the evaluation cannot be folded. 555 OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId 556 = diag::note_invalid_subexpr_in_const_expr, 557 unsigned ExtraNotes = 0) { 558 if (EvalStatus.Diag) { 559 // If we have a prior diagnostic, it will be noting that the expression 560 // isn't a constant expression. This diagnostic is more important, 561 // unless we require this evaluation to produce a constant expression. 562 // 563 // FIXME: We might want to show both diagnostics to the user in 564 // EM_ConstantFold mode. 565 if (!EvalStatus.Diag->empty()) { 566 switch (EvalMode) { 567 case EM_ConstantFold: 568 case EM_IgnoreSideEffects: 569 case EM_EvaluateForOverflow: 570 if (!EvalStatus.HasSideEffects) 571 break; 572 // We've had side-effects; we want the diagnostic from them, not 573 // some later problem. 574 case EM_ConstantExpression: 575 case EM_PotentialConstantExpression: 576 HasActiveDiagnostic = false; 577 return OptionalDiagnostic(); 578 } 579 } 580 581 unsigned CallStackNotes = CallStackDepth - 1; 582 unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit(); 583 if (Limit) 584 CallStackNotes = std::min(CallStackNotes, Limit + 1); 585 if (checkingPotentialConstantExpression()) 586 CallStackNotes = 0; 587 588 HasActiveDiagnostic = true; 589 EvalStatus.Diag->clear(); 590 EvalStatus.Diag->reserve(1 + ExtraNotes + CallStackNotes); 591 addDiag(Loc, DiagId); 592 if (!checkingPotentialConstantExpression()) 593 addCallStack(Limit); 594 return OptionalDiagnostic(&(*EvalStatus.Diag)[0].second); 595 } 596 HasActiveDiagnostic = false; 597 return OptionalDiagnostic(); 598 } 599 600 OptionalDiagnostic Diag(const Expr *E, diag::kind DiagId 601 = diag::note_invalid_subexpr_in_const_expr, 602 unsigned ExtraNotes = 0) { 603 if (EvalStatus.Diag) 604 return Diag(E->getExprLoc(), DiagId, ExtraNotes); 605 HasActiveDiagnostic = false; 606 return OptionalDiagnostic(); 607 } 608 609 /// Diagnose that the evaluation does not produce a C++11 core constant 610 /// expression. 611 /// 612 /// FIXME: Stop evaluating if we're in EM_ConstantExpression or 613 /// EM_PotentialConstantExpression mode and we produce one of these. 614 template<typename LocArg> 615 OptionalDiagnostic CCEDiag(LocArg Loc, diag::kind DiagId 616 = diag::note_invalid_subexpr_in_const_expr, 617 unsigned ExtraNotes = 0) { 618 // Don't override a previous diagnostic. Don't bother collecting 619 // diagnostics if we're evaluating for overflow. 620 if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) { 621 HasActiveDiagnostic = false; 622 return OptionalDiagnostic(); 623 } 624 return Diag(Loc, DiagId, ExtraNotes); 625 } 626 627 /// Add a note to a prior diagnostic. 628 OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId) { 629 if (!HasActiveDiagnostic) 630 return OptionalDiagnostic(); 631 return OptionalDiagnostic(&addDiag(Loc, DiagId)); 632 } 633 634 /// Add a stack of notes to a prior diagnostic. 635 void addNotes(ArrayRef<PartialDiagnosticAt> Diags) { 636 if (HasActiveDiagnostic) { 637 EvalStatus.Diag->insert(EvalStatus.Diag->end(), 638 Diags.begin(), Diags.end()); 639 } 640 } 641 642 /// Should we continue evaluation after encountering a side-effect that we 643 /// couldn't model? 644 bool keepEvaluatingAfterSideEffect() { 645 switch (EvalMode) { 646 case EM_PotentialConstantExpression: 647 case EM_EvaluateForOverflow: 648 case EM_IgnoreSideEffects: 649 return true; 650 651 case EM_ConstantExpression: 652 case EM_ConstantFold: 653 return false; 654 } 655 llvm_unreachable("Missed EvalMode case"); 656 } 657 658 /// Note that we have had a side-effect, and determine whether we should 659 /// keep evaluating. 660 bool noteSideEffect() { 661 EvalStatus.HasSideEffects = true; 662 return keepEvaluatingAfterSideEffect(); 663 } 664 665 /// Should we continue evaluation as much as possible after encountering a 666 /// construct which can't be reduced to a value? 667 bool keepEvaluatingAfterFailure() { 668 if (!StepsLeft) 669 return false; 670 671 switch (EvalMode) { 672 case EM_PotentialConstantExpression: 673 case EM_EvaluateForOverflow: 674 return true; 675 676 case EM_ConstantExpression: 677 case EM_ConstantFold: 678 case EM_IgnoreSideEffects: 679 return false; 680 } 681 llvm_unreachable("Missed EvalMode case"); 682 } 683 }; 684 685 /// Object used to treat all foldable expressions as constant expressions. 686 struct FoldConstant { 687 EvalInfo &Info; 688 bool Enabled; 689 bool HadNoPriorDiags; 690 EvalInfo::EvaluationMode OldMode; 691 692 explicit FoldConstant(EvalInfo &Info, bool Enabled) 693 : Info(Info), 694 Enabled(Enabled), 695 HadNoPriorDiags(Info.EvalStatus.Diag && 696 Info.EvalStatus.Diag->empty() && 697 !Info.EvalStatus.HasSideEffects), 698 OldMode(Info.EvalMode) { 699 if (Enabled && Info.EvalMode == EvalInfo::EM_ConstantExpression) 700 Info.EvalMode = EvalInfo::EM_ConstantFold; 701 } 702 void keepDiagnostics() { Enabled = false; } 703 ~FoldConstant() { 704 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() && 705 !Info.EvalStatus.HasSideEffects) 706 Info.EvalStatus.Diag->clear(); 707 Info.EvalMode = OldMode; 708 } 709 }; 710 711 /// RAII object used to suppress diagnostics and side-effects from a 712 /// speculative evaluation. 713 class SpeculativeEvaluationRAII { 714 EvalInfo &Info; 715 Expr::EvalStatus Old; 716 717 public: 718 SpeculativeEvaluationRAII(EvalInfo &Info, 719 SmallVectorImpl<PartialDiagnosticAt> *NewDiag = 0) 720 : Info(Info), Old(Info.EvalStatus) { 721 Info.EvalStatus.Diag = NewDiag; 722 // If we're speculatively evaluating, we may have skipped over some 723 // evaluations and missed out a side effect. 724 Info.EvalStatus.HasSideEffects = true; 725 } 726 ~SpeculativeEvaluationRAII() { 727 Info.EvalStatus = Old; 728 } 729 }; 730 731 /// RAII object wrapping a full-expression or block scope, and handling 732 /// the ending of the lifetime of temporaries created within it. 733 template<bool IsFullExpression> 734 class ScopeRAII { 735 EvalInfo &Info; 736 unsigned OldStackSize; 737 public: 738 ScopeRAII(EvalInfo &Info) 739 : Info(Info), OldStackSize(Info.CleanupStack.size()) {} 740 ~ScopeRAII() { 741 // Body moved to a static method to encourage the compiler to inline away 742 // instances of this class. 743 cleanup(Info, OldStackSize); 744 } 745 private: 746 static void cleanup(EvalInfo &Info, unsigned OldStackSize) { 747 unsigned NewEnd = OldStackSize; 748 for (unsigned I = OldStackSize, N = Info.CleanupStack.size(); 749 I != N; ++I) { 750 if (IsFullExpression && Info.CleanupStack[I].isLifetimeExtended()) { 751 // Full-expression cleanup of a lifetime-extended temporary: nothing 752 // to do, just move this cleanup to the right place in the stack. 753 std::swap(Info.CleanupStack[I], Info.CleanupStack[NewEnd]); 754 ++NewEnd; 755 } else { 756 // End the lifetime of the object. 757 Info.CleanupStack[I].endLifetime(); 758 } 759 } 760 Info.CleanupStack.erase(Info.CleanupStack.begin() + NewEnd, 761 Info.CleanupStack.end()); 762 } 763 }; 764 typedef ScopeRAII<false> BlockScopeRAII; 765 typedef ScopeRAII<true> FullExpressionRAII; 766} 767 768bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E, 769 CheckSubobjectKind CSK) { 770 if (Invalid) 771 return false; 772 if (isOnePastTheEnd()) { 773 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject) 774 << CSK; 775 setInvalid(); 776 return false; 777 } 778 return true; 779} 780 781void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info, 782 const Expr *E, uint64_t N) { 783 if (MostDerivedPathLength == Entries.size() && MostDerivedArraySize) 784 Info.CCEDiag(E, diag::note_constexpr_array_index) 785 << static_cast<int>(N) << /*array*/ 0 786 << static_cast<unsigned>(MostDerivedArraySize); 787 else 788 Info.CCEDiag(E, diag::note_constexpr_array_index) 789 << static_cast<int>(N) << /*non-array*/ 1; 790 setInvalid(); 791} 792 793CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, 794 const FunctionDecl *Callee, const LValue *This, 795 APValue *Arguments) 796 : Info(Info), Caller(Info.CurrentCall), CallLoc(CallLoc), Callee(Callee), 797 Index(Info.NextCallIndex++), This(This), Arguments(Arguments) { 798 Info.CurrentCall = this; 799 ++Info.CallStackDepth; 800} 801 802CallStackFrame::~CallStackFrame() { 803 assert(Info.CurrentCall == this && "calls retired out of order"); 804 --Info.CallStackDepth; 805 Info.CurrentCall = Caller; 806} 807 808APValue &CallStackFrame::createTemporary(const void *Key, 809 bool IsLifetimeExtended) { 810 APValue &Result = Temporaries[Key]; 811 assert(Result.isUninit() && "temporary created multiple times"); 812 Info.CleanupStack.push_back(Cleanup(&Result, IsLifetimeExtended)); 813 return Result; 814} 815 816static void describeCall(CallStackFrame *Frame, raw_ostream &Out); 817 818void EvalInfo::addCallStack(unsigned Limit) { 819 // Determine which calls to skip, if any. 820 unsigned ActiveCalls = CallStackDepth - 1; 821 unsigned SkipStart = ActiveCalls, SkipEnd = SkipStart; 822 if (Limit && Limit < ActiveCalls) { 823 SkipStart = Limit / 2 + Limit % 2; 824 SkipEnd = ActiveCalls - Limit / 2; 825 } 826 827 // Walk the call stack and add the diagnostics. 828 unsigned CallIdx = 0; 829 for (CallStackFrame *Frame = CurrentCall; Frame != &BottomFrame; 830 Frame = Frame->Caller, ++CallIdx) { 831 // Skip this call? 832 if (CallIdx >= SkipStart && CallIdx < SkipEnd) { 833 if (CallIdx == SkipStart) { 834 // Note that we're skipping calls. 835 addDiag(Frame->CallLoc, diag::note_constexpr_calls_suppressed) 836 << unsigned(ActiveCalls - Limit); 837 } 838 continue; 839 } 840 841 SmallVector<char, 128> Buffer; 842 llvm::raw_svector_ostream Out(Buffer); 843 describeCall(Frame, Out); 844 addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str(); 845 } 846} 847 848namespace { 849 struct ComplexValue { 850 private: 851 bool IsInt; 852 853 public: 854 APSInt IntReal, IntImag; 855 APFloat FloatReal, FloatImag; 856 857 ComplexValue() : FloatReal(APFloat::Bogus), FloatImag(APFloat::Bogus) {} 858 859 void makeComplexFloat() { IsInt = false; } 860 bool isComplexFloat() const { return !IsInt; } 861 APFloat &getComplexFloatReal() { return FloatReal; } 862 APFloat &getComplexFloatImag() { return FloatImag; } 863 864 void makeComplexInt() { IsInt = true; } 865 bool isComplexInt() const { return IsInt; } 866 APSInt &getComplexIntReal() { return IntReal; } 867 APSInt &getComplexIntImag() { return IntImag; } 868 869 void moveInto(APValue &v) const { 870 if (isComplexFloat()) 871 v = APValue(FloatReal, FloatImag); 872 else 873 v = APValue(IntReal, IntImag); 874 } 875 void setFrom(const APValue &v) { 876 assert(v.isComplexFloat() || v.isComplexInt()); 877 if (v.isComplexFloat()) { 878 makeComplexFloat(); 879 FloatReal = v.getComplexFloatReal(); 880 FloatImag = v.getComplexFloatImag(); 881 } else { 882 makeComplexInt(); 883 IntReal = v.getComplexIntReal(); 884 IntImag = v.getComplexIntImag(); 885 } 886 } 887 }; 888 889 struct LValue { 890 APValue::LValueBase Base; 891 CharUnits Offset; 892 unsigned CallIndex; 893 SubobjectDesignator Designator; 894 895 const APValue::LValueBase getLValueBase() const { return Base; } 896 CharUnits &getLValueOffset() { return Offset; } 897 const CharUnits &getLValueOffset() const { return Offset; } 898 unsigned getLValueCallIndex() const { return CallIndex; } 899 SubobjectDesignator &getLValueDesignator() { return Designator; } 900 const SubobjectDesignator &getLValueDesignator() const { return Designator;} 901 902 void moveInto(APValue &V) const { 903 if (Designator.Invalid) 904 V = APValue(Base, Offset, APValue::NoLValuePath(), CallIndex); 905 else 906 V = APValue(Base, Offset, Designator.Entries, 907 Designator.IsOnePastTheEnd, CallIndex); 908 } 909 void setFrom(ASTContext &Ctx, const APValue &V) { 910 assert(V.isLValue()); 911 Base = V.getLValueBase(); 912 Offset = V.getLValueOffset(); 913 CallIndex = V.getLValueCallIndex(); 914 Designator = SubobjectDesignator(Ctx, V); 915 } 916 917 void set(APValue::LValueBase B, unsigned I = 0) { 918 Base = B; 919 Offset = CharUnits::Zero(); 920 CallIndex = I; 921 Designator = SubobjectDesignator(getType(B)); 922 } 923 924 // Check that this LValue is not based on a null pointer. If it is, produce 925 // a diagnostic and mark the designator as invalid. 926 bool checkNullPointer(EvalInfo &Info, const Expr *E, 927 CheckSubobjectKind CSK) { 928 if (Designator.Invalid) 929 return false; 930 if (!Base) { 931 Info.CCEDiag(E, diag::note_constexpr_null_subobject) 932 << CSK; 933 Designator.setInvalid(); 934 return false; 935 } 936 return true; 937 } 938 939 // Check this LValue refers to an object. If not, set the designator to be 940 // invalid and emit a diagnostic. 941 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { 942 // Outside C++11, do not build a designator referring to a subobject of 943 // any object: we won't use such a designator for anything. 944 if (!Info.getLangOpts().CPlusPlus11) 945 Designator.setInvalid(); 946 return checkNullPointer(Info, E, CSK) && 947 Designator.checkSubobject(Info, E, CSK); 948 } 949 950 void addDecl(EvalInfo &Info, const Expr *E, 951 const Decl *D, bool Virtual = false) { 952 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base)) 953 Designator.addDeclUnchecked(D, Virtual); 954 } 955 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) { 956 if (checkSubobject(Info, E, CSK_ArrayToPointer)) 957 Designator.addArrayUnchecked(CAT); 958 } 959 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) { 960 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real)) 961 Designator.addComplexUnchecked(EltTy, Imag); 962 } 963 void adjustIndex(EvalInfo &Info, const Expr *E, uint64_t N) { 964 if (checkNullPointer(Info, E, CSK_ArrayIndex)) 965 Designator.adjustIndex(Info, E, N); 966 } 967 }; 968 969 struct MemberPtr { 970 MemberPtr() {} 971 explicit MemberPtr(const ValueDecl *Decl) : 972 DeclAndIsDerivedMember(Decl, false), Path() {} 973 974 /// The member or (direct or indirect) field referred to by this member 975 /// pointer, or 0 if this is a null member pointer. 976 const ValueDecl *getDecl() const { 977 return DeclAndIsDerivedMember.getPointer(); 978 } 979 /// Is this actually a member of some type derived from the relevant class? 980 bool isDerivedMember() const { 981 return DeclAndIsDerivedMember.getInt(); 982 } 983 /// Get the class which the declaration actually lives in. 984 const CXXRecordDecl *getContainingRecord() const { 985 return cast<CXXRecordDecl>( 986 DeclAndIsDerivedMember.getPointer()->getDeclContext()); 987 } 988 989 void moveInto(APValue &V) const { 990 V = APValue(getDecl(), isDerivedMember(), Path); 991 } 992 void setFrom(const APValue &V) { 993 assert(V.isMemberPointer()); 994 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl()); 995 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember()); 996 Path.clear(); 997 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath(); 998 Path.insert(Path.end(), P.begin(), P.end()); 999 } 1000 1001 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating 1002 /// whether the member is a member of some class derived from the class type 1003 /// of the member pointer. 1004 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember; 1005 /// Path - The path of base/derived classes from the member declaration's 1006 /// class (exclusive) to the class type of the member pointer (inclusive). 1007 SmallVector<const CXXRecordDecl*, 4> Path; 1008 1009 /// Perform a cast towards the class of the Decl (either up or down the 1010 /// hierarchy). 1011 bool castBack(const CXXRecordDecl *Class) { 1012 assert(!Path.empty()); 1013 const CXXRecordDecl *Expected; 1014 if (Path.size() >= 2) 1015 Expected = Path[Path.size() - 2]; 1016 else 1017 Expected = getContainingRecord(); 1018 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) { 1019 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*), 1020 // if B does not contain the original member and is not a base or 1021 // derived class of the class containing the original member, the result 1022 // of the cast is undefined. 1023 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to 1024 // (D::*). We consider that to be a language defect. 1025 return false; 1026 } 1027 Path.pop_back(); 1028 return true; 1029 } 1030 /// Perform a base-to-derived member pointer cast. 1031 bool castToDerived(const CXXRecordDecl *Derived) { 1032 if (!getDecl()) 1033 return true; 1034 if (!isDerivedMember()) { 1035 Path.push_back(Derived); 1036 return true; 1037 } 1038 if (!castBack(Derived)) 1039 return false; 1040 if (Path.empty()) 1041 DeclAndIsDerivedMember.setInt(false); 1042 return true; 1043 } 1044 /// Perform a derived-to-base member pointer cast. 1045 bool castToBase(const CXXRecordDecl *Base) { 1046 if (!getDecl()) 1047 return true; 1048 if (Path.empty()) 1049 DeclAndIsDerivedMember.setInt(true); 1050 if (isDerivedMember()) { 1051 Path.push_back(Base); 1052 return true; 1053 } 1054 return castBack(Base); 1055 } 1056 }; 1057 1058 /// Compare two member pointers, which are assumed to be of the same type. 1059 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) { 1060 if (!LHS.getDecl() || !RHS.getDecl()) 1061 return !LHS.getDecl() && !RHS.getDecl(); 1062 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl()) 1063 return false; 1064 return LHS.Path == RHS.Path; 1065 } 1066} 1067 1068static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E); 1069static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, 1070 const LValue &This, const Expr *E, 1071 bool AllowNonLiteralTypes = false); 1072static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info); 1073static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info); 1074static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, 1075 EvalInfo &Info); 1076static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info); 1077static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info); 1078static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, 1079 EvalInfo &Info); 1080static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info); 1081static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info); 1082static bool EvaluateAtomic(const Expr *E, APValue &Result, EvalInfo &Info); 1083 1084//===----------------------------------------------------------------------===// 1085// Misc utilities 1086//===----------------------------------------------------------------------===// 1087 1088/// Produce a string describing the given constexpr call. 1089static void describeCall(CallStackFrame *Frame, raw_ostream &Out) { 1090 unsigned ArgIndex = 0; 1091 bool IsMemberCall = isa<CXXMethodDecl>(Frame->Callee) && 1092 !isa<CXXConstructorDecl>(Frame->Callee) && 1093 cast<CXXMethodDecl>(Frame->Callee)->isInstance(); 1094 1095 if (!IsMemberCall) 1096 Out << *Frame->Callee << '('; 1097 1098 if (Frame->This && IsMemberCall) { 1099 APValue Val; 1100 Frame->This->moveInto(Val); 1101 Val.printPretty(Out, Frame->Info.Ctx, 1102 Frame->This->Designator.MostDerivedType); 1103 // FIXME: Add parens around Val if needed. 1104 Out << "->" << *Frame->Callee << '('; 1105 IsMemberCall = false; 1106 } 1107 1108 for (FunctionDecl::param_const_iterator I = Frame->Callee->param_begin(), 1109 E = Frame->Callee->param_end(); I != E; ++I, ++ArgIndex) { 1110 if (ArgIndex > (unsigned)IsMemberCall) 1111 Out << ", "; 1112 1113 const ParmVarDecl *Param = *I; 1114 const APValue &Arg = Frame->Arguments[ArgIndex]; 1115 Arg.printPretty(Out, Frame->Info.Ctx, Param->getType()); 1116 1117 if (ArgIndex == 0 && IsMemberCall) 1118 Out << "->" << *Frame->Callee << '('; 1119 } 1120 1121 Out << ')'; 1122} 1123 1124/// Evaluate an expression to see if it had side-effects, and discard its 1125/// result. 1126/// \return \c true if the caller should keep evaluating. 1127static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) { 1128 APValue Scratch; 1129 if (!Evaluate(Scratch, Info, E)) 1130 // We don't need the value, but we might have skipped a side effect here. 1131 return Info.noteSideEffect(); 1132 return true; 1133} 1134 1135/// Sign- or zero-extend a value to 64 bits. If it's already 64 bits, just 1136/// return its existing value. 1137static int64_t getExtValue(const APSInt &Value) { 1138 return Value.isSigned() ? Value.getSExtValue() 1139 : static_cast<int64_t>(Value.getZExtValue()); 1140} 1141 1142/// Should this call expression be treated as a string literal? 1143static bool IsStringLiteralCall(const CallExpr *E) { 1144 unsigned Builtin = E->isBuiltinCall(); 1145 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString || 1146 Builtin == Builtin::BI__builtin___NSStringMakeConstantString); 1147} 1148 1149static bool IsGlobalLValue(APValue::LValueBase B) { 1150 // C++11 [expr.const]p3 An address constant expression is a prvalue core 1151 // constant expression of pointer type that evaluates to... 1152 1153 // ... a null pointer value, or a prvalue core constant expression of type 1154 // std::nullptr_t. 1155 if (!B) return true; 1156 1157 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { 1158 // ... the address of an object with static storage duration, 1159 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 1160 return VD->hasGlobalStorage(); 1161 // ... the address of a function, 1162 return isa<FunctionDecl>(D); 1163 } 1164 1165 const Expr *E = B.get<const Expr*>(); 1166 switch (E->getStmtClass()) { 1167 default: 1168 return false; 1169 case Expr::CompoundLiteralExprClass: { 1170 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 1171 return CLE->isFileScope() && CLE->isLValue(); 1172 } 1173 case Expr::MaterializeTemporaryExprClass: 1174 // A materialized temporary might have been lifetime-extended to static 1175 // storage duration. 1176 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static; 1177 // A string literal has static storage duration. 1178 case Expr::StringLiteralClass: 1179 case Expr::PredefinedExprClass: 1180 case Expr::ObjCStringLiteralClass: 1181 case Expr::ObjCEncodeExprClass: 1182 case Expr::CXXTypeidExprClass: 1183 case Expr::CXXUuidofExprClass: 1184 return true; 1185 case Expr::CallExprClass: 1186 return IsStringLiteralCall(cast<CallExpr>(E)); 1187 // For GCC compatibility, &&label has static storage duration. 1188 case Expr::AddrLabelExprClass: 1189 return true; 1190 // A Block literal expression may be used as the initialization value for 1191 // Block variables at global or local static scope. 1192 case Expr::BlockExprClass: 1193 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures(); 1194 case Expr::ImplicitValueInitExprClass: 1195 // FIXME: 1196 // We can never form an lvalue with an implicit value initialization as its 1197 // base through expression evaluation, so these only appear in one case: the 1198 // implicit variable declaration we invent when checking whether a constexpr 1199 // constructor can produce a constant expression. We must assume that such 1200 // an expression might be a global lvalue. 1201 return true; 1202 } 1203} 1204 1205static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) { 1206 assert(Base && "no location for a null lvalue"); 1207 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 1208 if (VD) 1209 Info.Note(VD->getLocation(), diag::note_declared_at); 1210 else 1211 Info.Note(Base.get<const Expr*>()->getExprLoc(), 1212 diag::note_constexpr_temporary_here); 1213} 1214 1215/// Check that this reference or pointer core constant expression is a valid 1216/// value for an address or reference constant expression. Return true if we 1217/// can fold this expression, whether or not it's a constant expression. 1218static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc, 1219 QualType Type, const LValue &LVal) { 1220 bool IsReferenceType = Type->isReferenceType(); 1221 1222 APValue::LValueBase Base = LVal.getLValueBase(); 1223 const SubobjectDesignator &Designator = LVal.getLValueDesignator(); 1224 1225 // Check that the object is a global. Note that the fake 'this' object we 1226 // manufacture when checking potential constant expressions is conservatively 1227 // assumed to be global here. 1228 if (!IsGlobalLValue(Base)) { 1229 if (Info.getLangOpts().CPlusPlus11) { 1230 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 1231 Info.Diag(Loc, diag::note_constexpr_non_global, 1) 1232 << IsReferenceType << !Designator.Entries.empty() 1233 << !!VD << VD; 1234 NoteLValueLocation(Info, Base); 1235 } else { 1236 Info.Diag(Loc); 1237 } 1238 // Don't allow references to temporaries to escape. 1239 return false; 1240 } 1241 assert((Info.checkingPotentialConstantExpression() || 1242 LVal.getLValueCallIndex() == 0) && 1243 "have call index for global lvalue"); 1244 1245 // Check if this is a thread-local variable. 1246 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) { 1247 if (const VarDecl *Var = dyn_cast<const VarDecl>(VD)) { 1248 if (Var->getTLSKind()) 1249 return false; 1250 } 1251 } 1252 1253 // Allow address constant expressions to be past-the-end pointers. This is 1254 // an extension: the standard requires them to point to an object. 1255 if (!IsReferenceType) 1256 return true; 1257 1258 // A reference constant expression must refer to an object. 1259 if (!Base) { 1260 // FIXME: diagnostic 1261 Info.CCEDiag(Loc); 1262 return true; 1263 } 1264 1265 // Does this refer one past the end of some object? 1266 if (Designator.isOnePastTheEnd()) { 1267 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 1268 Info.Diag(Loc, diag::note_constexpr_past_end, 1) 1269 << !Designator.Entries.empty() << !!VD << VD; 1270 NoteLValueLocation(Info, Base); 1271 } 1272 1273 return true; 1274} 1275 1276/// Check that this core constant expression is of literal type, and if not, 1277/// produce an appropriate diagnostic. 1278static bool CheckLiteralType(EvalInfo &Info, const Expr *E, 1279 const LValue *This = 0) { 1280 if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx)) 1281 return true; 1282 1283 // C++1y: A constant initializer for an object o [...] may also invoke 1284 // constexpr constructors for o and its subobjects even if those objects 1285 // are of non-literal class types. 1286 if (Info.getLangOpts().CPlusPlus1y && This && 1287 Info.EvaluatingDecl == This->getLValueBase()) 1288 return true; 1289 1290 // Prvalue constant expressions must be of literal types. 1291 if (Info.getLangOpts().CPlusPlus11) 1292 Info.Diag(E, diag::note_constexpr_nonliteral) 1293 << E->getType(); 1294 else 1295 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1296 return false; 1297} 1298 1299/// Check that this core constant expression value is a valid value for a 1300/// constant expression. If not, report an appropriate diagnostic. Does not 1301/// check that the expression is of literal type. 1302static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, 1303 QualType Type, const APValue &Value) { 1304 if (Value.isUninit()) { 1305 Info.Diag(DiagLoc, diag::note_constexpr_uninitialized) 1306 << true << Type; 1307 return false; 1308 } 1309 1310 // Core issue 1454: For a literal constant expression of array or class type, 1311 // each subobject of its value shall have been initialized by a constant 1312 // expression. 1313 if (Value.isArray()) { 1314 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType(); 1315 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) { 1316 if (!CheckConstantExpression(Info, DiagLoc, EltTy, 1317 Value.getArrayInitializedElt(I))) 1318 return false; 1319 } 1320 if (!Value.hasArrayFiller()) 1321 return true; 1322 return CheckConstantExpression(Info, DiagLoc, EltTy, 1323 Value.getArrayFiller()); 1324 } 1325 if (Value.isUnion() && Value.getUnionField()) { 1326 return CheckConstantExpression(Info, DiagLoc, 1327 Value.getUnionField()->getType(), 1328 Value.getUnionValue()); 1329 } 1330 if (Value.isStruct()) { 1331 RecordDecl *RD = Type->castAs<RecordType>()->getDecl(); 1332 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) { 1333 unsigned BaseIndex = 0; 1334 for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), 1335 End = CD->bases_end(); I != End; ++I, ++BaseIndex) { 1336 if (!CheckConstantExpression(Info, DiagLoc, I->getType(), 1337 Value.getStructBase(BaseIndex))) 1338 return false; 1339 } 1340 } 1341 for (RecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end(); 1342 I != E; ++I) { 1343 if (!CheckConstantExpression(Info, DiagLoc, I->getType(), 1344 Value.getStructField(I->getFieldIndex()))) 1345 return false; 1346 } 1347 } 1348 1349 if (Value.isLValue()) { 1350 LValue LVal; 1351 LVal.setFrom(Info.Ctx, Value); 1352 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal); 1353 } 1354 1355 // Everything else is fine. 1356 return true; 1357} 1358 1359const ValueDecl *GetLValueBaseDecl(const LValue &LVal) { 1360 return LVal.Base.dyn_cast<const ValueDecl*>(); 1361} 1362 1363static bool IsLiteralLValue(const LValue &Value) { 1364 if (Value.CallIndex) 1365 return false; 1366 const Expr *E = Value.Base.dyn_cast<const Expr*>(); 1367 return E && !isa<MaterializeTemporaryExpr>(E); 1368} 1369 1370static bool IsWeakLValue(const LValue &Value) { 1371 const ValueDecl *Decl = GetLValueBaseDecl(Value); 1372 return Decl && Decl->isWeak(); 1373} 1374 1375static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) { 1376 // A null base expression indicates a null pointer. These are always 1377 // evaluatable, and they are false unless the offset is zero. 1378 if (!Value.getLValueBase()) { 1379 Result = !Value.getLValueOffset().isZero(); 1380 return true; 1381 } 1382 1383 // We have a non-null base. These are generally known to be true, but if it's 1384 // a weak declaration it can be null at runtime. 1385 Result = true; 1386 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>(); 1387 return !Decl || !Decl->isWeak(); 1388} 1389 1390static bool HandleConversionToBool(const APValue &Val, bool &Result) { 1391 switch (Val.getKind()) { 1392 case APValue::Uninitialized: 1393 return false; 1394 case APValue::Int: 1395 Result = Val.getInt().getBoolValue(); 1396 return true; 1397 case APValue::Float: 1398 Result = !Val.getFloat().isZero(); 1399 return true; 1400 case APValue::ComplexInt: 1401 Result = Val.getComplexIntReal().getBoolValue() || 1402 Val.getComplexIntImag().getBoolValue(); 1403 return true; 1404 case APValue::ComplexFloat: 1405 Result = !Val.getComplexFloatReal().isZero() || 1406 !Val.getComplexFloatImag().isZero(); 1407 return true; 1408 case APValue::LValue: 1409 return EvalPointerValueAsBool(Val, Result); 1410 case APValue::MemberPointer: 1411 Result = Val.getMemberPointerDecl(); 1412 return true; 1413 case APValue::Vector: 1414 case APValue::Array: 1415 case APValue::Struct: 1416 case APValue::Union: 1417 case APValue::AddrLabelDiff: 1418 return false; 1419 } 1420 1421 llvm_unreachable("unknown APValue kind"); 1422} 1423 1424static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result, 1425 EvalInfo &Info) { 1426 assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition"); 1427 APValue Val; 1428 if (!Evaluate(Val, Info, E)) 1429 return false; 1430 return HandleConversionToBool(Val, Result); 1431} 1432 1433template<typename T> 1434static void HandleOverflow(EvalInfo &Info, const Expr *E, 1435 const T &SrcValue, QualType DestType) { 1436 Info.CCEDiag(E, diag::note_constexpr_overflow) 1437 << SrcValue << DestType; 1438} 1439 1440static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E, 1441 QualType SrcType, const APFloat &Value, 1442 QualType DestType, APSInt &Result) { 1443 unsigned DestWidth = Info.Ctx.getIntWidth(DestType); 1444 // Determine whether we are converting to unsigned or signed. 1445 bool DestSigned = DestType->isSignedIntegerOrEnumerationType(); 1446 1447 Result = APSInt(DestWidth, !DestSigned); 1448 bool ignored; 1449 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored) 1450 & APFloat::opInvalidOp) 1451 HandleOverflow(Info, E, Value, DestType); 1452 return true; 1453} 1454 1455static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E, 1456 QualType SrcType, QualType DestType, 1457 APFloat &Result) { 1458 APFloat Value = Result; 1459 bool ignored; 1460 if (Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), 1461 APFloat::rmNearestTiesToEven, &ignored) 1462 & APFloat::opOverflow) 1463 HandleOverflow(Info, E, Value, DestType); 1464 return true; 1465} 1466 1467static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E, 1468 QualType DestType, QualType SrcType, 1469 APSInt &Value) { 1470 unsigned DestWidth = Info.Ctx.getIntWidth(DestType); 1471 APSInt Result = Value; 1472 // Figure out if this is a truncate, extend or noop cast. 1473 // If the input is signed, do a sign extend, noop, or truncate. 1474 Result = Result.extOrTrunc(DestWidth); 1475 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType()); 1476 return Result; 1477} 1478 1479static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E, 1480 QualType SrcType, const APSInt &Value, 1481 QualType DestType, APFloat &Result) { 1482 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1); 1483 if (Result.convertFromAPInt(Value, Value.isSigned(), 1484 APFloat::rmNearestTiesToEven) 1485 & APFloat::opOverflow) 1486 HandleOverflow(Info, E, Value, DestType); 1487 return true; 1488} 1489 1490static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E, 1491 APValue &Value, const FieldDecl *FD) { 1492 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield"); 1493 1494 if (!Value.isInt()) { 1495 // Trying to store a pointer-cast-to-integer into a bitfield. 1496 // FIXME: In this case, we should provide the diagnostic for casting 1497 // a pointer to an integer. 1498 assert(Value.isLValue() && "integral value neither int nor lvalue?"); 1499 Info.Diag(E); 1500 return false; 1501 } 1502 1503 APSInt &Int = Value.getInt(); 1504 unsigned OldBitWidth = Int.getBitWidth(); 1505 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx); 1506 if (NewBitWidth < OldBitWidth) 1507 Int = Int.trunc(NewBitWidth).extend(OldBitWidth); 1508 return true; 1509} 1510 1511static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E, 1512 llvm::APInt &Res) { 1513 APValue SVal; 1514 if (!Evaluate(SVal, Info, E)) 1515 return false; 1516 if (SVal.isInt()) { 1517 Res = SVal.getInt(); 1518 return true; 1519 } 1520 if (SVal.isFloat()) { 1521 Res = SVal.getFloat().bitcastToAPInt(); 1522 return true; 1523 } 1524 if (SVal.isVector()) { 1525 QualType VecTy = E->getType(); 1526 unsigned VecSize = Info.Ctx.getTypeSize(VecTy); 1527 QualType EltTy = VecTy->castAs<VectorType>()->getElementType(); 1528 unsigned EltSize = Info.Ctx.getTypeSize(EltTy); 1529 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); 1530 Res = llvm::APInt::getNullValue(VecSize); 1531 for (unsigned i = 0; i < SVal.getVectorLength(); i++) { 1532 APValue &Elt = SVal.getVectorElt(i); 1533 llvm::APInt EltAsInt; 1534 if (Elt.isInt()) { 1535 EltAsInt = Elt.getInt(); 1536 } else if (Elt.isFloat()) { 1537 EltAsInt = Elt.getFloat().bitcastToAPInt(); 1538 } else { 1539 // Don't try to handle vectors of anything other than int or float 1540 // (not sure if it's possible to hit this case). 1541 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1542 return false; 1543 } 1544 unsigned BaseEltSize = EltAsInt.getBitWidth(); 1545 if (BigEndian) 1546 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize); 1547 else 1548 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize); 1549 } 1550 return true; 1551 } 1552 // Give up if the input isn't an int, float, or vector. For example, we 1553 // reject "(v4i16)(intptr_t)&a". 1554 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1555 return false; 1556} 1557 1558/// Perform the given integer operation, which is known to need at most BitWidth 1559/// bits, and check for overflow in the original type (if that type was not an 1560/// unsigned type). 1561template<typename Operation> 1562static APSInt CheckedIntArithmetic(EvalInfo &Info, const Expr *E, 1563 const APSInt &LHS, const APSInt &RHS, 1564 unsigned BitWidth, Operation Op) { 1565 if (LHS.isUnsigned()) 1566 return Op(LHS, RHS); 1567 1568 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false); 1569 APSInt Result = Value.trunc(LHS.getBitWidth()); 1570 if (Result.extend(BitWidth) != Value) { 1571 if (Info.checkingForOverflow()) 1572 Info.Ctx.getDiagnostics().Report(E->getExprLoc(), 1573 diag::warn_integer_constant_overflow) 1574 << Result.toString(10) << E->getType(); 1575 else 1576 HandleOverflow(Info, E, Value, E->getType()); 1577 } 1578 return Result; 1579} 1580 1581/// Perform the given binary integer operation. 1582static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS, 1583 BinaryOperatorKind Opcode, APSInt RHS, 1584 APSInt &Result) { 1585 switch (Opcode) { 1586 default: 1587 Info.Diag(E); 1588 return false; 1589 case BO_Mul: 1590 Result = CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2, 1591 std::multiplies<APSInt>()); 1592 return true; 1593 case BO_Add: 1594 Result = CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, 1595 std::plus<APSInt>()); 1596 return true; 1597 case BO_Sub: 1598 Result = CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, 1599 std::minus<APSInt>()); 1600 return true; 1601 case BO_And: Result = LHS & RHS; return true; 1602 case BO_Xor: Result = LHS ^ RHS; return true; 1603 case BO_Or: Result = LHS | RHS; return true; 1604 case BO_Div: 1605 case BO_Rem: 1606 if (RHS == 0) { 1607 Info.Diag(E, diag::note_expr_divide_by_zero); 1608 return false; 1609 } 1610 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. 1611 if (RHS.isNegative() && RHS.isAllOnesValue() && 1612 LHS.isSigned() && LHS.isMinSignedValue()) 1613 HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), E->getType()); 1614 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS); 1615 return true; 1616 case BO_Shl: { 1617 if (Info.getLangOpts().OpenCL) 1618 // OpenCL 6.3j: shift values are effectively % word size of LHS. 1619 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), 1620 static_cast<uint64_t>(LHS.getBitWidth() - 1)), 1621 RHS.isUnsigned()); 1622 else if (RHS.isSigned() && RHS.isNegative()) { 1623 // During constant-folding, a negative shift is an opposite shift. Such 1624 // a shift is not a constant expression. 1625 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; 1626 RHS = -RHS; 1627 goto shift_right; 1628 } 1629 shift_left: 1630 // C++11 [expr.shift]p1: Shift width must be less than the bit width of 1631 // the shifted type. 1632 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); 1633 if (SA != RHS) { 1634 Info.CCEDiag(E, diag::note_constexpr_large_shift) 1635 << RHS << E->getType() << LHS.getBitWidth(); 1636 } else if (LHS.isSigned()) { 1637 // C++11 [expr.shift]p2: A signed left shift must have a non-negative 1638 // operand, and must not overflow the corresponding unsigned type. 1639 if (LHS.isNegative()) 1640 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS; 1641 else if (LHS.countLeadingZeros() < SA) 1642 Info.CCEDiag(E, diag::note_constexpr_lshift_discards); 1643 } 1644 Result = LHS << SA; 1645 return true; 1646 } 1647 case BO_Shr: { 1648 if (Info.getLangOpts().OpenCL) 1649 // OpenCL 6.3j: shift values are effectively % word size of LHS. 1650 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), 1651 static_cast<uint64_t>(LHS.getBitWidth() - 1)), 1652 RHS.isUnsigned()); 1653 else if (RHS.isSigned() && RHS.isNegative()) { 1654 // During constant-folding, a negative shift is an opposite shift. Such a 1655 // shift is not a constant expression. 1656 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; 1657 RHS = -RHS; 1658 goto shift_left; 1659 } 1660 shift_right: 1661 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the 1662 // shifted type. 1663 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); 1664 if (SA != RHS) 1665 Info.CCEDiag(E, diag::note_constexpr_large_shift) 1666 << RHS << E->getType() << LHS.getBitWidth(); 1667 Result = LHS >> SA; 1668 return true; 1669 } 1670 1671 case BO_LT: Result = LHS < RHS; return true; 1672 case BO_GT: Result = LHS > RHS; return true; 1673 case BO_LE: Result = LHS <= RHS; return true; 1674 case BO_GE: Result = LHS >= RHS; return true; 1675 case BO_EQ: Result = LHS == RHS; return true; 1676 case BO_NE: Result = LHS != RHS; return true; 1677 } 1678} 1679 1680/// Perform the given binary floating-point operation, in-place, on LHS. 1681static bool handleFloatFloatBinOp(EvalInfo &Info, const Expr *E, 1682 APFloat &LHS, BinaryOperatorKind Opcode, 1683 const APFloat &RHS) { 1684 switch (Opcode) { 1685 default: 1686 Info.Diag(E); 1687 return false; 1688 case BO_Mul: 1689 LHS.multiply(RHS, APFloat::rmNearestTiesToEven); 1690 break; 1691 case BO_Add: 1692 LHS.add(RHS, APFloat::rmNearestTiesToEven); 1693 break; 1694 case BO_Sub: 1695 LHS.subtract(RHS, APFloat::rmNearestTiesToEven); 1696 break; 1697 case BO_Div: 1698 LHS.divide(RHS, APFloat::rmNearestTiesToEven); 1699 break; 1700 } 1701 1702 if (LHS.isInfinity() || LHS.isNaN()) 1703 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN(); 1704 return true; 1705} 1706 1707/// Cast an lvalue referring to a base subobject to a derived class, by 1708/// truncating the lvalue's path to the given length. 1709static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result, 1710 const RecordDecl *TruncatedType, 1711 unsigned TruncatedElements) { 1712 SubobjectDesignator &D = Result.Designator; 1713 1714 // Check we actually point to a derived class object. 1715 if (TruncatedElements == D.Entries.size()) 1716 return true; 1717 assert(TruncatedElements >= D.MostDerivedPathLength && 1718 "not casting to a derived class"); 1719 if (!Result.checkSubobject(Info, E, CSK_Derived)) 1720 return false; 1721 1722 // Truncate the path to the subobject, and remove any derived-to-base offsets. 1723 const RecordDecl *RD = TruncatedType; 1724 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) { 1725 if (RD->isInvalidDecl()) return false; 1726 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 1727 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]); 1728 if (isVirtualBaseClass(D.Entries[I])) 1729 Result.Offset -= Layout.getVBaseClassOffset(Base); 1730 else 1731 Result.Offset -= Layout.getBaseClassOffset(Base); 1732 RD = Base; 1733 } 1734 D.Entries.resize(TruncatedElements); 1735 return true; 1736} 1737 1738static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj, 1739 const CXXRecordDecl *Derived, 1740 const CXXRecordDecl *Base, 1741 const ASTRecordLayout *RL = 0) { 1742 if (!RL) { 1743 if (Derived->isInvalidDecl()) return false; 1744 RL = &Info.Ctx.getASTRecordLayout(Derived); 1745 } 1746 1747 Obj.getLValueOffset() += RL->getBaseClassOffset(Base); 1748 Obj.addDecl(Info, E, Base, /*Virtual*/ false); 1749 return true; 1750} 1751 1752static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj, 1753 const CXXRecordDecl *DerivedDecl, 1754 const CXXBaseSpecifier *Base) { 1755 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl(); 1756 1757 if (!Base->isVirtual()) 1758 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl); 1759 1760 SubobjectDesignator &D = Obj.Designator; 1761 if (D.Invalid) 1762 return false; 1763 1764 // Extract most-derived object and corresponding type. 1765 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl(); 1766 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength)) 1767 return false; 1768 1769 // Find the virtual base class. 1770 if (DerivedDecl->isInvalidDecl()) return false; 1771 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl); 1772 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl); 1773 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true); 1774 return true; 1775} 1776 1777static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E, 1778 QualType Type, LValue &Result) { 1779 for (CastExpr::path_const_iterator PathI = E->path_begin(), 1780 PathE = E->path_end(); 1781 PathI != PathE; ++PathI) { 1782 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(), 1783 *PathI)) 1784 return false; 1785 Type = (*PathI)->getType(); 1786 } 1787 return true; 1788} 1789 1790/// Update LVal to refer to the given field, which must be a member of the type 1791/// currently described by LVal. 1792static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal, 1793 const FieldDecl *FD, 1794 const ASTRecordLayout *RL = 0) { 1795 if (!RL) { 1796 if (FD->getParent()->isInvalidDecl()) return false; 1797 RL = &Info.Ctx.getASTRecordLayout(FD->getParent()); 1798 } 1799 1800 unsigned I = FD->getFieldIndex(); 1801 LVal.Offset += Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)); 1802 LVal.addDecl(Info, E, FD); 1803 return true; 1804} 1805 1806/// Update LVal to refer to the given indirect field. 1807static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E, 1808 LValue &LVal, 1809 const IndirectFieldDecl *IFD) { 1810 for (IndirectFieldDecl::chain_iterator C = IFD->chain_begin(), 1811 CE = IFD->chain_end(); C != CE; ++C) 1812 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(*C))) 1813 return false; 1814 return true; 1815} 1816 1817/// Get the size of the given type in char units. 1818static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc, 1819 QualType Type, CharUnits &Size) { 1820 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc 1821 // extension. 1822 if (Type->isVoidType() || Type->isFunctionType()) { 1823 Size = CharUnits::One(); 1824 return true; 1825 } 1826 1827 if (!Type->isConstantSizeType()) { 1828 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2. 1829 // FIXME: Better diagnostic. 1830 Info.Diag(Loc); 1831 return false; 1832 } 1833 1834 Size = Info.Ctx.getTypeSizeInChars(Type); 1835 return true; 1836} 1837 1838/// Update a pointer value to model pointer arithmetic. 1839/// \param Info - Information about the ongoing evaluation. 1840/// \param E - The expression being evaluated, for diagnostic purposes. 1841/// \param LVal - The pointer value to be updated. 1842/// \param EltTy - The pointee type represented by LVal. 1843/// \param Adjustment - The adjustment, in objects of type EltTy, to add. 1844static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, 1845 LValue &LVal, QualType EltTy, 1846 int64_t Adjustment) { 1847 CharUnits SizeOfPointee; 1848 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee)) 1849 return false; 1850 1851 // Compute the new offset in the appropriate width. 1852 LVal.Offset += Adjustment * SizeOfPointee; 1853 LVal.adjustIndex(Info, E, Adjustment); 1854 return true; 1855} 1856 1857/// Update an lvalue to refer to a component of a complex number. 1858/// \param Info - Information about the ongoing evaluation. 1859/// \param LVal - The lvalue to be updated. 1860/// \param EltTy - The complex number's component type. 1861/// \param Imag - False for the real component, true for the imaginary. 1862static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E, 1863 LValue &LVal, QualType EltTy, 1864 bool Imag) { 1865 if (Imag) { 1866 CharUnits SizeOfComponent; 1867 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent)) 1868 return false; 1869 LVal.Offset += SizeOfComponent; 1870 } 1871 LVal.addComplex(Info, E, EltTy, Imag); 1872 return true; 1873} 1874 1875/// Try to evaluate the initializer for a variable declaration. 1876/// 1877/// \param Info Information about the ongoing evaluation. 1878/// \param E An expression to be used when printing diagnostics. 1879/// \param VD The variable whose initializer should be obtained. 1880/// \param Frame The frame in which the variable was created. Must be null 1881/// if this variable is not local to the evaluation. 1882/// \param Result Filled in with a pointer to the value of the variable. 1883static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E, 1884 const VarDecl *VD, CallStackFrame *Frame, 1885 APValue *&Result) { 1886 // If this is a parameter to an active constexpr function call, perform 1887 // argument substitution. 1888 if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) { 1889 // Assume arguments of a potential constant expression are unknown 1890 // constant expressions. 1891 if (Info.checkingPotentialConstantExpression()) 1892 return false; 1893 if (!Frame || !Frame->Arguments) { 1894 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1895 return false; 1896 } 1897 Result = &Frame->Arguments[PVD->getFunctionScopeIndex()]; 1898 return true; 1899 } 1900 1901 // If this is a local variable, dig out its value. 1902 if (Frame) { 1903 Result = Frame->getTemporary(VD); 1904 assert(Result && "missing value for local variable"); 1905 return true; 1906 } 1907 1908 // Dig out the initializer, and use the declaration which it's attached to. 1909 const Expr *Init = VD->getAnyInitializer(VD); 1910 if (!Init || Init->isValueDependent()) { 1911 // If we're checking a potential constant expression, the variable could be 1912 // initialized later. 1913 if (!Info.checkingPotentialConstantExpression()) 1914 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1915 return false; 1916 } 1917 1918 // If we're currently evaluating the initializer of this declaration, use that 1919 // in-flight value. 1920 if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) { 1921 Result = Info.EvaluatingDeclValue; 1922 return true; 1923 } 1924 1925 // Never evaluate the initializer of a weak variable. We can't be sure that 1926 // this is the definition which will be used. 1927 if (VD->isWeak()) { 1928 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 1929 return false; 1930 } 1931 1932 // Check that we can fold the initializer. In C++, we will have already done 1933 // this in the cases where it matters for conformance. 1934 SmallVector<PartialDiagnosticAt, 8> Notes; 1935 if (!VD->evaluateValue(Notes)) { 1936 Info.Diag(E, diag::note_constexpr_var_init_non_constant, 1937 Notes.size() + 1) << VD; 1938 Info.Note(VD->getLocation(), diag::note_declared_at); 1939 Info.addNotes(Notes); 1940 return false; 1941 } else if (!VD->checkInitIsICE()) { 1942 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1943 Notes.size() + 1) << VD; 1944 Info.Note(VD->getLocation(), diag::note_declared_at); 1945 Info.addNotes(Notes); 1946 } 1947 1948 Result = VD->getEvaluatedValue(); 1949 return true; 1950} 1951 1952static bool IsConstNonVolatile(QualType T) { 1953 Qualifiers Quals = T.getQualifiers(); 1954 return Quals.hasConst() && !Quals.hasVolatile(); 1955} 1956 1957/// Get the base index of the given base class within an APValue representing 1958/// the given derived class. 1959static unsigned getBaseIndex(const CXXRecordDecl *Derived, 1960 const CXXRecordDecl *Base) { 1961 Base = Base->getCanonicalDecl(); 1962 unsigned Index = 0; 1963 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(), 1964 E = Derived->bases_end(); I != E; ++I, ++Index) { 1965 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base) 1966 return Index; 1967 } 1968 1969 llvm_unreachable("base class missing from derived class's bases list"); 1970} 1971 1972/// Extract the value of a character from a string literal. 1973static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit, 1974 uint64_t Index) { 1975 // FIXME: Support PredefinedExpr, ObjCEncodeExpr, MakeStringConstant 1976 const StringLiteral *S = cast<StringLiteral>(Lit); 1977 const ConstantArrayType *CAT = 1978 Info.Ctx.getAsConstantArrayType(S->getType()); 1979 assert(CAT && "string literal isn't an array"); 1980 QualType CharType = CAT->getElementType(); 1981 assert(CharType->isIntegerType() && "unexpected character type"); 1982 1983 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), 1984 CharType->isUnsignedIntegerType()); 1985 if (Index < S->getLength()) 1986 Value = S->getCodeUnit(Index); 1987 return Value; 1988} 1989 1990// Expand a string literal into an array of characters. 1991static void expandStringLiteral(EvalInfo &Info, const Expr *Lit, 1992 APValue &Result) { 1993 const StringLiteral *S = cast<StringLiteral>(Lit); 1994 const ConstantArrayType *CAT = 1995 Info.Ctx.getAsConstantArrayType(S->getType()); 1996 assert(CAT && "string literal isn't an array"); 1997 QualType CharType = CAT->getElementType(); 1998 assert(CharType->isIntegerType() && "unexpected character type"); 1999 2000 unsigned Elts = CAT->getSize().getZExtValue(); 2001 Result = APValue(APValue::UninitArray(), 2002 std::min(S->getLength(), Elts), Elts); 2003 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), 2004 CharType->isUnsignedIntegerType()); 2005 if (Result.hasArrayFiller()) 2006 Result.getArrayFiller() = APValue(Value); 2007 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) { 2008 Value = S->getCodeUnit(I); 2009 Result.getArrayInitializedElt(I) = APValue(Value); 2010 } 2011} 2012 2013// Expand an array so that it has more than Index filled elements. 2014static void expandArray(APValue &Array, unsigned Index) { 2015 unsigned Size = Array.getArraySize(); 2016 assert(Index < Size); 2017 2018 // Always at least double the number of elements for which we store a value. 2019 unsigned OldElts = Array.getArrayInitializedElts(); 2020 unsigned NewElts = std::max(Index+1, OldElts * 2); 2021 NewElts = std::min(Size, std::max(NewElts, 8u)); 2022 2023 // Copy the data across. 2024 APValue NewValue(APValue::UninitArray(), NewElts, Size); 2025 for (unsigned I = 0; I != OldElts; ++I) 2026 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I)); 2027 for (unsigned I = OldElts; I != NewElts; ++I) 2028 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller(); 2029 if (NewValue.hasArrayFiller()) 2030 NewValue.getArrayFiller() = Array.getArrayFiller(); 2031 Array.swap(NewValue); 2032} 2033 2034/// Kinds of access we can perform on an object, for diagnostics. 2035enum AccessKinds { 2036 AK_Read, 2037 AK_Assign, 2038 AK_Increment, 2039 AK_Decrement 2040}; 2041 2042/// A handle to a complete object (an object that is not a subobject of 2043/// another object). 2044struct CompleteObject { 2045 /// The value of the complete object. 2046 APValue *Value; 2047 /// The type of the complete object. 2048 QualType Type; 2049 2050 CompleteObject() : Value(0) {} 2051 CompleteObject(APValue *Value, QualType Type) 2052 : Value(Value), Type(Type) { 2053 assert(Value && "missing value for complete object"); 2054 } 2055 2056 LLVM_EXPLICIT operator bool() const { return Value; } 2057}; 2058 2059/// Find the designated sub-object of an rvalue. 2060template<typename SubobjectHandler> 2061typename SubobjectHandler::result_type 2062findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj, 2063 const SubobjectDesignator &Sub, SubobjectHandler &handler) { 2064 if (Sub.Invalid) 2065 // A diagnostic will have already been produced. 2066 return handler.failed(); 2067 if (Sub.isOnePastTheEnd()) { 2068 if (Info.getLangOpts().CPlusPlus11) 2069 Info.Diag(E, diag::note_constexpr_access_past_end) 2070 << handler.AccessKind; 2071 else 2072 Info.Diag(E); 2073 return handler.failed(); 2074 } 2075 2076 APValue *O = Obj.Value; 2077 QualType ObjType = Obj.Type; 2078 const FieldDecl *LastField = 0; 2079 2080 // Walk the designator's path to find the subobject. 2081 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) { 2082 if (O->isUninit()) { 2083 if (!Info.checkingPotentialConstantExpression()) 2084 Info.Diag(E, diag::note_constexpr_access_uninit) << handler.AccessKind; 2085 return handler.failed(); 2086 } 2087 2088 if (I == N) { 2089 if (!handler.found(*O, ObjType)) 2090 return false; 2091 2092 // If we modified a bit-field, truncate it to the right width. 2093 if (handler.AccessKind != AK_Read && 2094 LastField && LastField->isBitField() && 2095 !truncateBitfieldValue(Info, E, *O, LastField)) 2096 return false; 2097 2098 return true; 2099 } 2100 2101 LastField = 0; 2102 if (ObjType->isArrayType()) { 2103 // Next subobject is an array element. 2104 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType); 2105 assert(CAT && "vla in literal type?"); 2106 uint64_t Index = Sub.Entries[I].ArrayIndex; 2107 if (CAT->getSize().ule(Index)) { 2108 // Note, it should not be possible to form a pointer with a valid 2109 // designator which points more than one past the end of the array. 2110 if (Info.getLangOpts().CPlusPlus11) 2111 Info.Diag(E, diag::note_constexpr_access_past_end) 2112 << handler.AccessKind; 2113 else 2114 Info.Diag(E); 2115 return handler.failed(); 2116 } 2117 2118 ObjType = CAT->getElementType(); 2119 2120 // An array object is represented as either an Array APValue or as an 2121 // LValue which refers to a string literal. 2122 if (O->isLValue()) { 2123 assert(I == N - 1 && "extracting subobject of character?"); 2124 assert(!O->hasLValuePath() || O->getLValuePath().empty()); 2125 if (handler.AccessKind != AK_Read) 2126 expandStringLiteral(Info, O->getLValueBase().get<const Expr *>(), 2127 *O); 2128 else 2129 return handler.foundString(*O, ObjType, Index); 2130 } 2131 2132 if (O->getArrayInitializedElts() > Index) 2133 O = &O->getArrayInitializedElt(Index); 2134 else if (handler.AccessKind != AK_Read) { 2135 expandArray(*O, Index); 2136 O = &O->getArrayInitializedElt(Index); 2137 } else 2138 O = &O->getArrayFiller(); 2139 } else if (ObjType->isAnyComplexType()) { 2140 // Next subobject is a complex number. 2141 uint64_t Index = Sub.Entries[I].ArrayIndex; 2142 if (Index > 1) { 2143 if (Info.getLangOpts().CPlusPlus11) 2144 Info.Diag(E, diag::note_constexpr_access_past_end) 2145 << handler.AccessKind; 2146 else 2147 Info.Diag(E); 2148 return handler.failed(); 2149 } 2150 2151 bool WasConstQualified = ObjType.isConstQualified(); 2152 ObjType = ObjType->castAs<ComplexType>()->getElementType(); 2153 if (WasConstQualified) 2154 ObjType.addConst(); 2155 2156 assert(I == N - 1 && "extracting subobject of scalar?"); 2157 if (O->isComplexInt()) { 2158 return handler.found(Index ? O->getComplexIntImag() 2159 : O->getComplexIntReal(), ObjType); 2160 } else { 2161 assert(O->isComplexFloat()); 2162 return handler.found(Index ? O->getComplexFloatImag() 2163 : O->getComplexFloatReal(), ObjType); 2164 } 2165 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) { 2166 if (Field->isMutable() && handler.AccessKind == AK_Read) { 2167 Info.Diag(E, diag::note_constexpr_ltor_mutable, 1) 2168 << Field; 2169 Info.Note(Field->getLocation(), diag::note_declared_at); 2170 return handler.failed(); 2171 } 2172 2173 // Next subobject is a class, struct or union field. 2174 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl(); 2175 if (RD->isUnion()) { 2176 const FieldDecl *UnionField = O->getUnionField(); 2177 if (!UnionField || 2178 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) { 2179 Info.Diag(E, diag::note_constexpr_access_inactive_union_member) 2180 << handler.AccessKind << Field << !UnionField << UnionField; 2181 return handler.failed(); 2182 } 2183 O = &O->getUnionValue(); 2184 } else 2185 O = &O->getStructField(Field->getFieldIndex()); 2186 2187 bool WasConstQualified = ObjType.isConstQualified(); 2188 ObjType = Field->getType(); 2189 if (WasConstQualified && !Field->isMutable()) 2190 ObjType.addConst(); 2191 2192 if (ObjType.isVolatileQualified()) { 2193 if (Info.getLangOpts().CPlusPlus) { 2194 // FIXME: Include a description of the path to the volatile subobject. 2195 Info.Diag(E, diag::note_constexpr_access_volatile_obj, 1) 2196 << handler.AccessKind << 2 << Field; 2197 Info.Note(Field->getLocation(), diag::note_declared_at); 2198 } else { 2199 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 2200 } 2201 return handler.failed(); 2202 } 2203 2204 LastField = Field; 2205 } else { 2206 // Next subobject is a base class. 2207 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl(); 2208 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]); 2209 O = &O->getStructBase(getBaseIndex(Derived, Base)); 2210 2211 bool WasConstQualified = ObjType.isConstQualified(); 2212 ObjType = Info.Ctx.getRecordType(Base); 2213 if (WasConstQualified) 2214 ObjType.addConst(); 2215 } 2216 } 2217} 2218 2219namespace { 2220struct ExtractSubobjectHandler { 2221 EvalInfo &Info; 2222 APValue &Result; 2223 2224 static const AccessKinds AccessKind = AK_Read; 2225 2226 typedef bool result_type; 2227 bool failed() { return false; } 2228 bool found(APValue &Subobj, QualType SubobjType) { 2229 Result = Subobj; 2230 return true; 2231 } 2232 bool found(APSInt &Value, QualType SubobjType) { 2233 Result = APValue(Value); 2234 return true; 2235 } 2236 bool found(APFloat &Value, QualType SubobjType) { 2237 Result = APValue(Value); 2238 return true; 2239 } 2240 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { 2241 Result = APValue(extractStringLiteralCharacter( 2242 Info, Subobj.getLValueBase().get<const Expr *>(), Character)); 2243 return true; 2244 } 2245}; 2246} // end anonymous namespace 2247 2248const AccessKinds ExtractSubobjectHandler::AccessKind; 2249 2250/// Extract the designated sub-object of an rvalue. 2251static bool extractSubobject(EvalInfo &Info, const Expr *E, 2252 const CompleteObject &Obj, 2253 const SubobjectDesignator &Sub, 2254 APValue &Result) { 2255 ExtractSubobjectHandler Handler = { Info, Result }; 2256 return findSubobject(Info, E, Obj, Sub, Handler); 2257} 2258 2259namespace { 2260struct ModifySubobjectHandler { 2261 EvalInfo &Info; 2262 APValue &NewVal; 2263 const Expr *E; 2264 2265 typedef bool result_type; 2266 static const AccessKinds AccessKind = AK_Assign; 2267 2268 bool checkConst(QualType QT) { 2269 // Assigning to a const object has undefined behavior. 2270 if (QT.isConstQualified()) { 2271 Info.Diag(E, diag::note_constexpr_modify_const_type) << QT; 2272 return false; 2273 } 2274 return true; 2275 } 2276 2277 bool failed() { return false; } 2278 bool found(APValue &Subobj, QualType SubobjType) { 2279 if (!checkConst(SubobjType)) 2280 return false; 2281 // We've been given ownership of NewVal, so just swap it in. 2282 Subobj.swap(NewVal); 2283 return true; 2284 } 2285 bool found(APSInt &Value, QualType SubobjType) { 2286 if (!checkConst(SubobjType)) 2287 return false; 2288 if (!NewVal.isInt()) { 2289 // Maybe trying to write a cast pointer value into a complex? 2290 Info.Diag(E); 2291 return false; 2292 } 2293 Value = NewVal.getInt(); 2294 return true; 2295 } 2296 bool found(APFloat &Value, QualType SubobjType) { 2297 if (!checkConst(SubobjType)) 2298 return false; 2299 Value = NewVal.getFloat(); 2300 return true; 2301 } 2302 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { 2303 llvm_unreachable("shouldn't encounter string elements with ExpandArrays"); 2304 } 2305}; 2306} // end anonymous namespace 2307 2308const AccessKinds ModifySubobjectHandler::AccessKind; 2309 2310/// Update the designated sub-object of an rvalue to the given value. 2311static bool modifySubobject(EvalInfo &Info, const Expr *E, 2312 const CompleteObject &Obj, 2313 const SubobjectDesignator &Sub, 2314 APValue &NewVal) { 2315 ModifySubobjectHandler Handler = { Info, NewVal, E }; 2316 return findSubobject(Info, E, Obj, Sub, Handler); 2317} 2318 2319/// Find the position where two subobject designators diverge, or equivalently 2320/// the length of the common initial subsequence. 2321static unsigned FindDesignatorMismatch(QualType ObjType, 2322 const SubobjectDesignator &A, 2323 const SubobjectDesignator &B, 2324 bool &WasArrayIndex) { 2325 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size()); 2326 for (/**/; I != N; ++I) { 2327 if (!ObjType.isNull() && 2328 (ObjType->isArrayType() || ObjType->isAnyComplexType())) { 2329 // Next subobject is an array element. 2330 if (A.Entries[I].ArrayIndex != B.Entries[I].ArrayIndex) { 2331 WasArrayIndex = true; 2332 return I; 2333 } 2334 if (ObjType->isAnyComplexType()) 2335 ObjType = ObjType->castAs<ComplexType>()->getElementType(); 2336 else 2337 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType(); 2338 } else { 2339 if (A.Entries[I].BaseOrMember != B.Entries[I].BaseOrMember) { 2340 WasArrayIndex = false; 2341 return I; 2342 } 2343 if (const FieldDecl *FD = getAsField(A.Entries[I])) 2344 // Next subobject is a field. 2345 ObjType = FD->getType(); 2346 else 2347 // Next subobject is a base class. 2348 ObjType = QualType(); 2349 } 2350 } 2351 WasArrayIndex = false; 2352 return I; 2353} 2354 2355/// Determine whether the given subobject designators refer to elements of the 2356/// same array object. 2357static bool AreElementsOfSameArray(QualType ObjType, 2358 const SubobjectDesignator &A, 2359 const SubobjectDesignator &B) { 2360 if (A.Entries.size() != B.Entries.size()) 2361 return false; 2362 2363 bool IsArray = A.MostDerivedArraySize != 0; 2364 if (IsArray && A.MostDerivedPathLength != A.Entries.size()) 2365 // A is a subobject of the array element. 2366 return false; 2367 2368 // If A (and B) designates an array element, the last entry will be the array 2369 // index. That doesn't have to match. Otherwise, we're in the 'implicit array 2370 // of length 1' case, and the entire path must match. 2371 bool WasArrayIndex; 2372 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex); 2373 return CommonLength >= A.Entries.size() - IsArray; 2374} 2375 2376/// Find the complete object to which an LValue refers. 2377CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E, AccessKinds AK, 2378 const LValue &LVal, QualType LValType) { 2379 if (!LVal.Base) { 2380 Info.Diag(E, diag::note_constexpr_access_null) << AK; 2381 return CompleteObject(); 2382 } 2383 2384 CallStackFrame *Frame = 0; 2385 if (LVal.CallIndex) { 2386 Frame = Info.getCallFrame(LVal.CallIndex); 2387 if (!Frame) { 2388 Info.Diag(E, diag::note_constexpr_lifetime_ended, 1) 2389 << AK << LVal.Base.is<const ValueDecl*>(); 2390 NoteLValueLocation(Info, LVal.Base); 2391 return CompleteObject(); 2392 } 2393 } 2394 2395 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type 2396 // is not a constant expression (even if the object is non-volatile). We also 2397 // apply this rule to C++98, in order to conform to the expected 'volatile' 2398 // semantics. 2399 if (LValType.isVolatileQualified()) { 2400 if (Info.getLangOpts().CPlusPlus) 2401 Info.Diag(E, diag::note_constexpr_access_volatile_type) 2402 << AK << LValType; 2403 else 2404 Info.Diag(E); 2405 return CompleteObject(); 2406 } 2407 2408 // Compute value storage location and type of base object. 2409 APValue *BaseVal = 0; 2410 QualType BaseType = getType(LVal.Base); 2411 2412 if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl*>()) { 2413 // In C++98, const, non-volatile integers initialized with ICEs are ICEs. 2414 // In C++11, constexpr, non-volatile variables initialized with constant 2415 // expressions are constant expressions too. Inside constexpr functions, 2416 // parameters are constant expressions even if they're non-const. 2417 // In C++1y, objects local to a constant expression (those with a Frame) are 2418 // both readable and writable inside constant expressions. 2419 // In C, such things can also be folded, although they are not ICEs. 2420 const VarDecl *VD = dyn_cast<VarDecl>(D); 2421 if (VD) { 2422 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx)) 2423 VD = VDef; 2424 } 2425 if (!VD || VD->isInvalidDecl()) { 2426 Info.Diag(E); 2427 return CompleteObject(); 2428 } 2429 2430 // Accesses of volatile-qualified objects are not allowed. 2431 if (BaseType.isVolatileQualified()) { 2432 if (Info.getLangOpts().CPlusPlus) { 2433 Info.Diag(E, diag::note_constexpr_access_volatile_obj, 1) 2434 << AK << 1 << VD; 2435 Info.Note(VD->getLocation(), diag::note_declared_at); 2436 } else { 2437 Info.Diag(E); 2438 } 2439 return CompleteObject(); 2440 } 2441 2442 // Unless we're looking at a local variable or argument in a constexpr call, 2443 // the variable we're reading must be const. 2444 if (!Frame) { 2445 if (Info.getLangOpts().CPlusPlus1y && 2446 VD == Info.EvaluatingDecl.dyn_cast<const ValueDecl *>()) { 2447 // OK, we can read and modify an object if we're in the process of 2448 // evaluating its initializer, because its lifetime began in this 2449 // evaluation. 2450 } else if (AK != AK_Read) { 2451 // All the remaining cases only permit reading. 2452 Info.Diag(E, diag::note_constexpr_modify_global); 2453 return CompleteObject(); 2454 } else if (VD->isConstexpr()) { 2455 // OK, we can read this variable. 2456 } else if (BaseType->isIntegralOrEnumerationType()) { 2457 if (!BaseType.isConstQualified()) { 2458 if (Info.getLangOpts().CPlusPlus) { 2459 Info.Diag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD; 2460 Info.Note(VD->getLocation(), diag::note_declared_at); 2461 } else { 2462 Info.Diag(E); 2463 } 2464 return CompleteObject(); 2465 } 2466 } else if (BaseType->isFloatingType() && BaseType.isConstQualified()) { 2467 // We support folding of const floating-point types, in order to make 2468 // static const data members of such types (supported as an extension) 2469 // more useful. 2470 if (Info.getLangOpts().CPlusPlus11) { 2471 Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; 2472 Info.Note(VD->getLocation(), diag::note_declared_at); 2473 } else { 2474 Info.CCEDiag(E); 2475 } 2476 } else { 2477 // FIXME: Allow folding of values of any literal type in all languages. 2478 if (Info.getLangOpts().CPlusPlus11) { 2479 Info.Diag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; 2480 Info.Note(VD->getLocation(), diag::note_declared_at); 2481 } else { 2482 Info.Diag(E); 2483 } 2484 return CompleteObject(); 2485 } 2486 } 2487 2488 if (!evaluateVarDeclInit(Info, E, VD, Frame, BaseVal)) 2489 return CompleteObject(); 2490 } else { 2491 const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); 2492 2493 if (!Frame) { 2494 if (const MaterializeTemporaryExpr *MTE = 2495 dyn_cast<MaterializeTemporaryExpr>(Base)) { 2496 assert(MTE->getStorageDuration() == SD_Static && 2497 "should have a frame for a non-global materialized temporary"); 2498 2499 // Per C++1y [expr.const]p2: 2500 // an lvalue-to-rvalue conversion [is not allowed unless it applies to] 2501 // - a [...] glvalue of integral or enumeration type that refers to 2502 // a non-volatile const object [...] 2503 // [...] 2504 // - a [...] glvalue of literal type that refers to a non-volatile 2505 // object whose lifetime began within the evaluation of e. 2506 // 2507 // C++11 misses the 'began within the evaluation of e' check and 2508 // instead allows all temporaries, including things like: 2509 // int &&r = 1; 2510 // int x = ++r; 2511 // constexpr int k = r; 2512 // Therefore we use the C++1y rules in C++11 too. 2513 const ValueDecl *VD = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>(); 2514 const ValueDecl *ED = MTE->getExtendingDecl(); 2515 if (!(BaseType.isConstQualified() && 2516 BaseType->isIntegralOrEnumerationType()) && 2517 !(VD && VD->getCanonicalDecl() == ED->getCanonicalDecl())) { 2518 Info.Diag(E, diag::note_constexpr_access_static_temporary, 1) << AK; 2519 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here); 2520 return CompleteObject(); 2521 } 2522 2523 BaseVal = Info.Ctx.getMaterializedTemporaryValue(MTE, false); 2524 assert(BaseVal && "got reference to unevaluated temporary"); 2525 } else { 2526 Info.Diag(E); 2527 return CompleteObject(); 2528 } 2529 } else { 2530 BaseVal = Frame->getTemporary(Base); 2531 assert(BaseVal && "missing value for temporary"); 2532 } 2533 2534 // Volatile temporary objects cannot be accessed in constant expressions. 2535 if (BaseType.isVolatileQualified()) { 2536 if (Info.getLangOpts().CPlusPlus) { 2537 Info.Diag(E, diag::note_constexpr_access_volatile_obj, 1) 2538 << AK << 0; 2539 Info.Note(Base->getExprLoc(), diag::note_constexpr_temporary_here); 2540 } else { 2541 Info.Diag(E); 2542 } 2543 return CompleteObject(); 2544 } 2545 } 2546 2547 // During the construction of an object, it is not yet 'const'. 2548 // FIXME: We don't set up EvaluatingDecl for local variables or temporaries, 2549 // and this doesn't do quite the right thing for const subobjects of the 2550 // object under construction. 2551 if (LVal.getLValueBase() == Info.EvaluatingDecl) { 2552 BaseType = Info.Ctx.getCanonicalType(BaseType); 2553 BaseType.removeLocalConst(); 2554 } 2555 2556 // In C++1y, we can't safely access any mutable state when we might be 2557 // evaluating after an unmodeled side effect or an evaluation failure. 2558 // 2559 // FIXME: Not all local state is mutable. Allow local constant subobjects 2560 // to be read here (but take care with 'mutable' fields). 2561 if (Frame && Info.getLangOpts().CPlusPlus1y && 2562 (Info.EvalStatus.HasSideEffects || Info.keepEvaluatingAfterFailure())) 2563 return CompleteObject(); 2564 2565 return CompleteObject(BaseVal, BaseType); 2566} 2567 2568/// \brief Perform an lvalue-to-rvalue conversion on the given glvalue. This 2569/// can also be used for 'lvalue-to-lvalue' conversions for looking up the 2570/// glvalue referred to by an entity of reference type. 2571/// 2572/// \param Info - Information about the ongoing evaluation. 2573/// \param Conv - The expression for which we are performing the conversion. 2574/// Used for diagnostics. 2575/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the 2576/// case of a non-class type). 2577/// \param LVal - The glvalue on which we are attempting to perform this action. 2578/// \param RVal - The produced value will be placed here. 2579static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, 2580 QualType Type, 2581 const LValue &LVal, APValue &RVal) { 2582 if (LVal.Designator.Invalid) 2583 return false; 2584 2585 // Check for special cases where there is no existing APValue to look at. 2586 const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); 2587 if (!LVal.Designator.Invalid && Base && !LVal.CallIndex && 2588 !Type.isVolatileQualified()) { 2589 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) { 2590 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the 2591 // initializer until now for such expressions. Such an expression can't be 2592 // an ICE in C, so this only matters for fold. 2593 assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?"); 2594 if (Type.isVolatileQualified()) { 2595 Info.Diag(Conv); 2596 return false; 2597 } 2598 APValue Lit; 2599 if (!Evaluate(Lit, Info, CLE->getInitializer())) 2600 return false; 2601 CompleteObject LitObj(&Lit, Base->getType()); 2602 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal); 2603 } else if (isa<StringLiteral>(Base)) { 2604 // We represent a string literal array as an lvalue pointing at the 2605 // corresponding expression, rather than building an array of chars. 2606 // FIXME: Support PredefinedExpr, ObjCEncodeExpr, MakeStringConstant 2607 APValue Str(Base, CharUnits::Zero(), APValue::NoLValuePath(), 0); 2608 CompleteObject StrObj(&Str, Base->getType()); 2609 return extractSubobject(Info, Conv, StrObj, LVal.Designator, RVal); 2610 } 2611 } 2612 2613 CompleteObject Obj = findCompleteObject(Info, Conv, AK_Read, LVal, Type); 2614 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal); 2615} 2616 2617/// Perform an assignment of Val to LVal. Takes ownership of Val. 2618static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal, 2619 QualType LValType, APValue &Val) { 2620 if (LVal.Designator.Invalid) 2621 return false; 2622 2623 if (!Info.getLangOpts().CPlusPlus1y) { 2624 Info.Diag(E); 2625 return false; 2626 } 2627 2628 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); 2629 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val); 2630} 2631 2632static bool isOverflowingIntegerType(ASTContext &Ctx, QualType T) { 2633 return T->isSignedIntegerType() && 2634 Ctx.getIntWidth(T) >= Ctx.getIntWidth(Ctx.IntTy); 2635} 2636 2637namespace { 2638struct CompoundAssignSubobjectHandler { 2639 EvalInfo &Info; 2640 const Expr *E; 2641 QualType PromotedLHSType; 2642 BinaryOperatorKind Opcode; 2643 const APValue &RHS; 2644 2645 static const AccessKinds AccessKind = AK_Assign; 2646 2647 typedef bool result_type; 2648 2649 bool checkConst(QualType QT) { 2650 // Assigning to a const object has undefined behavior. 2651 if (QT.isConstQualified()) { 2652 Info.Diag(E, diag::note_constexpr_modify_const_type) << QT; 2653 return false; 2654 } 2655 return true; 2656 } 2657 2658 bool failed() { return false; } 2659 bool found(APValue &Subobj, QualType SubobjType) { 2660 switch (Subobj.getKind()) { 2661 case APValue::Int: 2662 return found(Subobj.getInt(), SubobjType); 2663 case APValue::Float: 2664 return found(Subobj.getFloat(), SubobjType); 2665 case APValue::ComplexInt: 2666 case APValue::ComplexFloat: 2667 // FIXME: Implement complex compound assignment. 2668 Info.Diag(E); 2669 return false; 2670 case APValue::LValue: 2671 return foundPointer(Subobj, SubobjType); 2672 default: 2673 // FIXME: can this happen? 2674 Info.Diag(E); 2675 return false; 2676 } 2677 } 2678 bool found(APSInt &Value, QualType SubobjType) { 2679 if (!checkConst(SubobjType)) 2680 return false; 2681 2682 if (!SubobjType->isIntegerType() || !RHS.isInt()) { 2683 // We don't support compound assignment on integer-cast-to-pointer 2684 // values. 2685 Info.Diag(E); 2686 return false; 2687 } 2688 2689 APSInt LHS = HandleIntToIntCast(Info, E, PromotedLHSType, 2690 SubobjType, Value); 2691 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS)) 2692 return false; 2693 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS); 2694 return true; 2695 } 2696 bool found(APFloat &Value, QualType SubobjType) { 2697 return checkConst(SubobjType) && 2698 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType, 2699 Value) && 2700 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) && 2701 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value); 2702 } 2703 bool foundPointer(APValue &Subobj, QualType SubobjType) { 2704 if (!checkConst(SubobjType)) 2705 return false; 2706 2707 QualType PointeeType; 2708 if (const PointerType *PT = SubobjType->getAs<PointerType>()) 2709 PointeeType = PT->getPointeeType(); 2710 2711 if (PointeeType.isNull() || !RHS.isInt() || 2712 (Opcode != BO_Add && Opcode != BO_Sub)) { 2713 Info.Diag(E); 2714 return false; 2715 } 2716 2717 int64_t Offset = getExtValue(RHS.getInt()); 2718 if (Opcode == BO_Sub) 2719 Offset = -Offset; 2720 2721 LValue LVal; 2722 LVal.setFrom(Info.Ctx, Subobj); 2723 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset)) 2724 return false; 2725 LVal.moveInto(Subobj); 2726 return true; 2727 } 2728 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { 2729 llvm_unreachable("shouldn't encounter string elements here"); 2730 } 2731}; 2732} // end anonymous namespace 2733 2734const AccessKinds CompoundAssignSubobjectHandler::AccessKind; 2735 2736/// Perform a compound assignment of LVal <op>= RVal. 2737static bool handleCompoundAssignment( 2738 EvalInfo &Info, const Expr *E, 2739 const LValue &LVal, QualType LValType, QualType PromotedLValType, 2740 BinaryOperatorKind Opcode, const APValue &RVal) { 2741 if (LVal.Designator.Invalid) 2742 return false; 2743 2744 if (!Info.getLangOpts().CPlusPlus1y) { 2745 Info.Diag(E); 2746 return false; 2747 } 2748 2749 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); 2750 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode, 2751 RVal }; 2752 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); 2753} 2754 2755namespace { 2756struct IncDecSubobjectHandler { 2757 EvalInfo &Info; 2758 const Expr *E; 2759 AccessKinds AccessKind; 2760 APValue *Old; 2761 2762 typedef bool result_type; 2763 2764 bool checkConst(QualType QT) { 2765 // Assigning to a const object has undefined behavior. 2766 if (QT.isConstQualified()) { 2767 Info.Diag(E, diag::note_constexpr_modify_const_type) << QT; 2768 return false; 2769 } 2770 return true; 2771 } 2772 2773 bool failed() { return false; } 2774 bool found(APValue &Subobj, QualType SubobjType) { 2775 // Stash the old value. Also clear Old, so we don't clobber it later 2776 // if we're post-incrementing a complex. 2777 if (Old) { 2778 *Old = Subobj; 2779 Old = 0; 2780 } 2781 2782 switch (Subobj.getKind()) { 2783 case APValue::Int: 2784 return found(Subobj.getInt(), SubobjType); 2785 case APValue::Float: 2786 return found(Subobj.getFloat(), SubobjType); 2787 case APValue::ComplexInt: 2788 return found(Subobj.getComplexIntReal(), 2789 SubobjType->castAs<ComplexType>()->getElementType() 2790 .withCVRQualifiers(SubobjType.getCVRQualifiers())); 2791 case APValue::ComplexFloat: 2792 return found(Subobj.getComplexFloatReal(), 2793 SubobjType->castAs<ComplexType>()->getElementType() 2794 .withCVRQualifiers(SubobjType.getCVRQualifiers())); 2795 case APValue::LValue: 2796 return foundPointer(Subobj, SubobjType); 2797 default: 2798 // FIXME: can this happen? 2799 Info.Diag(E); 2800 return false; 2801 } 2802 } 2803 bool found(APSInt &Value, QualType SubobjType) { 2804 if (!checkConst(SubobjType)) 2805 return false; 2806 2807 if (!SubobjType->isIntegerType()) { 2808 // We don't support increment / decrement on integer-cast-to-pointer 2809 // values. 2810 Info.Diag(E); 2811 return false; 2812 } 2813 2814 if (Old) *Old = APValue(Value); 2815 2816 // bool arithmetic promotes to int, and the conversion back to bool 2817 // doesn't reduce mod 2^n, so special-case it. 2818 if (SubobjType->isBooleanType()) { 2819 if (AccessKind == AK_Increment) 2820 Value = 1; 2821 else 2822 Value = !Value; 2823 return true; 2824 } 2825 2826 bool WasNegative = Value.isNegative(); 2827 if (AccessKind == AK_Increment) { 2828 ++Value; 2829 2830 if (!WasNegative && Value.isNegative() && 2831 isOverflowingIntegerType(Info.Ctx, SubobjType)) { 2832 APSInt ActualValue(Value, /*IsUnsigned*/true); 2833 HandleOverflow(Info, E, ActualValue, SubobjType); 2834 } 2835 } else { 2836 --Value; 2837 2838 if (WasNegative && !Value.isNegative() && 2839 isOverflowingIntegerType(Info.Ctx, SubobjType)) { 2840 unsigned BitWidth = Value.getBitWidth(); 2841 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false); 2842 ActualValue.setBit(BitWidth); 2843 HandleOverflow(Info, E, ActualValue, SubobjType); 2844 } 2845 } 2846 return true; 2847 } 2848 bool found(APFloat &Value, QualType SubobjType) { 2849 if (!checkConst(SubobjType)) 2850 return false; 2851 2852 if (Old) *Old = APValue(Value); 2853 2854 APFloat One(Value.getSemantics(), 1); 2855 if (AccessKind == AK_Increment) 2856 Value.add(One, APFloat::rmNearestTiesToEven); 2857 else 2858 Value.subtract(One, APFloat::rmNearestTiesToEven); 2859 return true; 2860 } 2861 bool foundPointer(APValue &Subobj, QualType SubobjType) { 2862 if (!checkConst(SubobjType)) 2863 return false; 2864 2865 QualType PointeeType; 2866 if (const PointerType *PT = SubobjType->getAs<PointerType>()) 2867 PointeeType = PT->getPointeeType(); 2868 else { 2869 Info.Diag(E); 2870 return false; 2871 } 2872 2873 LValue LVal; 2874 LVal.setFrom(Info.Ctx, Subobj); 2875 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, 2876 AccessKind == AK_Increment ? 1 : -1)) 2877 return false; 2878 LVal.moveInto(Subobj); 2879 return true; 2880 } 2881 bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) { 2882 llvm_unreachable("shouldn't encounter string elements here"); 2883 } 2884}; 2885} // end anonymous namespace 2886 2887/// Perform an increment or decrement on LVal. 2888static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal, 2889 QualType LValType, bool IsIncrement, APValue *Old) { 2890 if (LVal.Designator.Invalid) 2891 return false; 2892 2893 if (!Info.getLangOpts().CPlusPlus1y) { 2894 Info.Diag(E); 2895 return false; 2896 } 2897 2898 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement; 2899 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType); 2900 IncDecSubobjectHandler Handler = { Info, E, AK, Old }; 2901 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); 2902} 2903 2904/// Build an lvalue for the object argument of a member function call. 2905static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object, 2906 LValue &This) { 2907 if (Object->getType()->isPointerType()) 2908 return EvaluatePointer(Object, This, Info); 2909 2910 if (Object->isGLValue()) 2911 return EvaluateLValue(Object, This, Info); 2912 2913 if (Object->getType()->isLiteralType(Info.Ctx)) 2914 return EvaluateTemporary(Object, This, Info); 2915 2916 return false; 2917} 2918 2919/// HandleMemberPointerAccess - Evaluate a member access operation and build an 2920/// lvalue referring to the result. 2921/// 2922/// \param Info - Information about the ongoing evaluation. 2923/// \param LV - An lvalue referring to the base of the member pointer. 2924/// \param RHS - The member pointer expression. 2925/// \param IncludeMember - Specifies whether the member itself is included in 2926/// the resulting LValue subobject designator. This is not possible when 2927/// creating a bound member function. 2928/// \return The field or method declaration to which the member pointer refers, 2929/// or 0 if evaluation fails. 2930static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, 2931 QualType LVType, 2932 LValue &LV, 2933 const Expr *RHS, 2934 bool IncludeMember = true) { 2935 MemberPtr MemPtr; 2936 if (!EvaluateMemberPointer(RHS, MemPtr, Info)) 2937 return 0; 2938 2939 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to 2940 // member value, the behavior is undefined. 2941 if (!MemPtr.getDecl()) { 2942 // FIXME: Specific diagnostic. 2943 Info.Diag(RHS); 2944 return 0; 2945 } 2946 2947 if (MemPtr.isDerivedMember()) { 2948 // This is a member of some derived class. Truncate LV appropriately. 2949 // The end of the derived-to-base path for the base object must match the 2950 // derived-to-base path for the member pointer. 2951 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() > 2952 LV.Designator.Entries.size()) { 2953 Info.Diag(RHS); 2954 return 0; 2955 } 2956 unsigned PathLengthToMember = 2957 LV.Designator.Entries.size() - MemPtr.Path.size(); 2958 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) { 2959 const CXXRecordDecl *LVDecl = getAsBaseClass( 2960 LV.Designator.Entries[PathLengthToMember + I]); 2961 const CXXRecordDecl *MPDecl = MemPtr.Path[I]; 2962 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) { 2963 Info.Diag(RHS); 2964 return 0; 2965 } 2966 } 2967 2968 // Truncate the lvalue to the appropriate derived class. 2969 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(), 2970 PathLengthToMember)) 2971 return 0; 2972 } else if (!MemPtr.Path.empty()) { 2973 // Extend the LValue path with the member pointer's path. 2974 LV.Designator.Entries.reserve(LV.Designator.Entries.size() + 2975 MemPtr.Path.size() + IncludeMember); 2976 2977 // Walk down to the appropriate base class. 2978 if (const PointerType *PT = LVType->getAs<PointerType>()) 2979 LVType = PT->getPointeeType(); 2980 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl(); 2981 assert(RD && "member pointer access on non-class-type expression"); 2982 // The first class in the path is that of the lvalue. 2983 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) { 2984 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1]; 2985 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base)) 2986 return 0; 2987 RD = Base; 2988 } 2989 // Finally cast to the class containing the member. 2990 if (!HandleLValueDirectBase(Info, RHS, LV, RD, 2991 MemPtr.getContainingRecord())) 2992 return 0; 2993 } 2994 2995 // Add the member. Note that we cannot build bound member functions here. 2996 if (IncludeMember) { 2997 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) { 2998 if (!HandleLValueMember(Info, RHS, LV, FD)) 2999 return 0; 3000 } else if (const IndirectFieldDecl *IFD = 3001 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) { 3002 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD)) 3003 return 0; 3004 } else { 3005 llvm_unreachable("can't construct reference to bound member function"); 3006 } 3007 } 3008 3009 return MemPtr.getDecl(); 3010} 3011 3012static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, 3013 const BinaryOperator *BO, 3014 LValue &LV, 3015 bool IncludeMember = true) { 3016 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI); 3017 3018 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) { 3019 if (Info.keepEvaluatingAfterFailure()) { 3020 MemberPtr MemPtr; 3021 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info); 3022 } 3023 return 0; 3024 } 3025 3026 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV, 3027 BO->getRHS(), IncludeMember); 3028} 3029 3030/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on 3031/// the provided lvalue, which currently refers to the base object. 3032static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E, 3033 LValue &Result) { 3034 SubobjectDesignator &D = Result.Designator; 3035 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived)) 3036 return false; 3037 3038 QualType TargetQT = E->getType(); 3039 if (const PointerType *PT = TargetQT->getAs<PointerType>()) 3040 TargetQT = PT->getPointeeType(); 3041 3042 // Check this cast lands within the final derived-to-base subobject path. 3043 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) { 3044 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) 3045 << D.MostDerivedType << TargetQT; 3046 return false; 3047 } 3048 3049 // Check the type of the final cast. We don't need to check the path, 3050 // since a cast can only be formed if the path is unique. 3051 unsigned NewEntriesSize = D.Entries.size() - E->path_size(); 3052 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl(); 3053 const CXXRecordDecl *FinalType; 3054 if (NewEntriesSize == D.MostDerivedPathLength) 3055 FinalType = D.MostDerivedType->getAsCXXRecordDecl(); 3056 else 3057 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]); 3058 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) { 3059 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) 3060 << D.MostDerivedType << TargetQT; 3061 return false; 3062 } 3063 3064 // Truncate the lvalue to the appropriate derived class. 3065 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize); 3066} 3067 3068namespace { 3069enum EvalStmtResult { 3070 /// Evaluation failed. 3071 ESR_Failed, 3072 /// Hit a 'return' statement. 3073 ESR_Returned, 3074 /// Evaluation succeeded. 3075 ESR_Succeeded, 3076 /// Hit a 'continue' statement. 3077 ESR_Continue, 3078 /// Hit a 'break' statement. 3079 ESR_Break, 3080 /// Still scanning for 'case' or 'default' statement. 3081 ESR_CaseNotFound 3082}; 3083} 3084 3085static bool EvaluateDecl(EvalInfo &Info, const Decl *D) { 3086 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) { 3087 // We don't need to evaluate the initializer for a static local. 3088 if (!VD->hasLocalStorage()) 3089 return true; 3090 3091 LValue Result; 3092 Result.set(VD, Info.CurrentCall->Index); 3093 APValue &Val = Info.CurrentCall->createTemporary(VD, true); 3094 3095 if (!VD->getInit()) { 3096 Info.Diag(D->getLocStart(), diag::note_constexpr_uninitialized) 3097 << false << VD->getType(); 3098 Val = APValue(); 3099 return false; 3100 } 3101 3102 if (!EvaluateInPlace(Val, Info, Result, VD->getInit())) { 3103 // Wipe out any partially-computed value, to allow tracking that this 3104 // evaluation failed. 3105 Val = APValue(); 3106 return false; 3107 } 3108 } 3109 3110 return true; 3111} 3112 3113/// Evaluate a condition (either a variable declaration or an expression). 3114static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl, 3115 const Expr *Cond, bool &Result) { 3116 FullExpressionRAII Scope(Info); 3117 if (CondDecl && !EvaluateDecl(Info, CondDecl)) 3118 return false; 3119 return EvaluateAsBooleanCondition(Cond, Result, Info); 3120} 3121 3122static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info, 3123 const Stmt *S, const SwitchCase *SC = 0); 3124 3125/// Evaluate the body of a loop, and translate the result as appropriate. 3126static EvalStmtResult EvaluateLoopBody(APValue &Result, EvalInfo &Info, 3127 const Stmt *Body, 3128 const SwitchCase *Case = 0) { 3129 BlockScopeRAII Scope(Info); 3130 switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case)) { 3131 case ESR_Break: 3132 return ESR_Succeeded; 3133 case ESR_Succeeded: 3134 case ESR_Continue: 3135 return ESR_Continue; 3136 case ESR_Failed: 3137 case ESR_Returned: 3138 case ESR_CaseNotFound: 3139 return ESR; 3140 } 3141 llvm_unreachable("Invalid EvalStmtResult!"); 3142} 3143 3144/// Evaluate a switch statement. 3145static EvalStmtResult EvaluateSwitch(APValue &Result, EvalInfo &Info, 3146 const SwitchStmt *SS) { 3147 BlockScopeRAII Scope(Info); 3148 3149 // Evaluate the switch condition. 3150 APSInt Value; 3151 { 3152 FullExpressionRAII Scope(Info); 3153 if (SS->getConditionVariable() && 3154 !EvaluateDecl(Info, SS->getConditionVariable())) 3155 return ESR_Failed; 3156 if (!EvaluateInteger(SS->getCond(), Value, Info)) 3157 return ESR_Failed; 3158 } 3159 3160 // Find the switch case corresponding to the value of the condition. 3161 // FIXME: Cache this lookup. 3162 const SwitchCase *Found = 0; 3163 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC; 3164 SC = SC->getNextSwitchCase()) { 3165 if (isa<DefaultStmt>(SC)) { 3166 Found = SC; 3167 continue; 3168 } 3169 3170 const CaseStmt *CS = cast<CaseStmt>(SC); 3171 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx); 3172 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx) 3173 : LHS; 3174 if (LHS <= Value && Value <= RHS) { 3175 Found = SC; 3176 break; 3177 } 3178 } 3179 3180 if (!Found) 3181 return ESR_Succeeded; 3182 3183 // Search the switch body for the switch case and evaluate it from there. 3184 switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found)) { 3185 case ESR_Break: 3186 return ESR_Succeeded; 3187 case ESR_Succeeded: 3188 case ESR_Continue: 3189 case ESR_Failed: 3190 case ESR_Returned: 3191 return ESR; 3192 case ESR_CaseNotFound: 3193 // This can only happen if the switch case is nested within a statement 3194 // expression. We have no intention of supporting that. 3195 Info.Diag(Found->getLocStart(), diag::note_constexpr_stmt_expr_unsupported); 3196 return ESR_Failed; 3197 } 3198 llvm_unreachable("Invalid EvalStmtResult!"); 3199} 3200 3201// Evaluate a statement. 3202static EvalStmtResult EvaluateStmt(APValue &Result, EvalInfo &Info, 3203 const Stmt *S, const SwitchCase *Case) { 3204 if (!Info.nextStep(S)) 3205 return ESR_Failed; 3206 3207 // If we're hunting down a 'case' or 'default' label, recurse through 3208 // substatements until we hit the label. 3209 if (Case) { 3210 // FIXME: We don't start the lifetime of objects whose initialization we 3211 // jump over. However, such objects must be of class type with a trivial 3212 // default constructor that initialize all subobjects, so must be empty, 3213 // so this almost never matters. 3214 switch (S->getStmtClass()) { 3215 case Stmt::CompoundStmtClass: 3216 // FIXME: Precompute which substatement of a compound statement we 3217 // would jump to, and go straight there rather than performing a 3218 // linear scan each time. 3219 case Stmt::LabelStmtClass: 3220 case Stmt::AttributedStmtClass: 3221 case Stmt::DoStmtClass: 3222 break; 3223 3224 case Stmt::CaseStmtClass: 3225 case Stmt::DefaultStmtClass: 3226 if (Case == S) 3227 Case = 0; 3228 break; 3229 3230 case Stmt::IfStmtClass: { 3231 // FIXME: Precompute which side of an 'if' we would jump to, and go 3232 // straight there rather than scanning both sides. 3233 const IfStmt *IS = cast<IfStmt>(S); 3234 3235 // Wrap the evaluation in a block scope, in case it's a DeclStmt 3236 // preceded by our switch label. 3237 BlockScopeRAII Scope(Info); 3238 3239 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case); 3240 if (ESR != ESR_CaseNotFound || !IS->getElse()) 3241 return ESR; 3242 return EvaluateStmt(Result, Info, IS->getElse(), Case); 3243 } 3244 3245 case Stmt::WhileStmtClass: { 3246 EvalStmtResult ESR = 3247 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case); 3248 if (ESR != ESR_Continue) 3249 return ESR; 3250 break; 3251 } 3252 3253 case Stmt::ForStmtClass: { 3254 const ForStmt *FS = cast<ForStmt>(S); 3255 EvalStmtResult ESR = 3256 EvaluateLoopBody(Result, Info, FS->getBody(), Case); 3257 if (ESR != ESR_Continue) 3258 return ESR; 3259 if (FS->getInc()) { 3260 FullExpressionRAII IncScope(Info); 3261 if (!EvaluateIgnoredValue(Info, FS->getInc())) 3262 return ESR_Failed; 3263 } 3264 break; 3265 } 3266 3267 case Stmt::DeclStmtClass: 3268 // FIXME: If the variable has initialization that can't be jumped over, 3269 // bail out of any immediately-surrounding compound-statement too. 3270 default: 3271 return ESR_CaseNotFound; 3272 } 3273 } 3274 3275 switch (S->getStmtClass()) { 3276 default: 3277 if (const Expr *E = dyn_cast<Expr>(S)) { 3278 // Don't bother evaluating beyond an expression-statement which couldn't 3279 // be evaluated. 3280 FullExpressionRAII Scope(Info); 3281 if (!EvaluateIgnoredValue(Info, E)) 3282 return ESR_Failed; 3283 return ESR_Succeeded; 3284 } 3285 3286 Info.Diag(S->getLocStart()); 3287 return ESR_Failed; 3288 3289 case Stmt::NullStmtClass: 3290 return ESR_Succeeded; 3291 3292 case Stmt::DeclStmtClass: { 3293 const DeclStmt *DS = cast<DeclStmt>(S); 3294 for (DeclStmt::const_decl_iterator DclIt = DS->decl_begin(), 3295 DclEnd = DS->decl_end(); DclIt != DclEnd; ++DclIt) { 3296 // Each declaration initialization is its own full-expression. 3297 // FIXME: This isn't quite right; if we're performing aggregate 3298 // initialization, each braced subexpression is its own full-expression. 3299 FullExpressionRAII Scope(Info); 3300 if (!EvaluateDecl(Info, *DclIt) && !Info.keepEvaluatingAfterFailure()) 3301 return ESR_Failed; 3302 } 3303 return ESR_Succeeded; 3304 } 3305 3306 case Stmt::ReturnStmtClass: { 3307 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue(); 3308 FullExpressionRAII Scope(Info); 3309 if (RetExpr && !Evaluate(Result, Info, RetExpr)) 3310 return ESR_Failed; 3311 return ESR_Returned; 3312 } 3313 3314 case Stmt::CompoundStmtClass: { 3315 BlockScopeRAII Scope(Info); 3316 3317 const CompoundStmt *CS = cast<CompoundStmt>(S); 3318 for (CompoundStmt::const_body_iterator BI = CS->body_begin(), 3319 BE = CS->body_end(); BI != BE; ++BI) { 3320 EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI, Case); 3321 if (ESR == ESR_Succeeded) 3322 Case = 0; 3323 else if (ESR != ESR_CaseNotFound) 3324 return ESR; 3325 } 3326 return Case ? ESR_CaseNotFound : ESR_Succeeded; 3327 } 3328 3329 case Stmt::IfStmtClass: { 3330 const IfStmt *IS = cast<IfStmt>(S); 3331 3332 // Evaluate the condition, as either a var decl or as an expression. 3333 BlockScopeRAII Scope(Info); 3334 bool Cond; 3335 if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond)) 3336 return ESR_Failed; 3337 3338 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) { 3339 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt); 3340 if (ESR != ESR_Succeeded) 3341 return ESR; 3342 } 3343 return ESR_Succeeded; 3344 } 3345 3346 case Stmt::WhileStmtClass: { 3347 const WhileStmt *WS = cast<WhileStmt>(S); 3348 while (true) { 3349 BlockScopeRAII Scope(Info); 3350 bool Continue; 3351 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(), 3352 Continue)) 3353 return ESR_Failed; 3354 if (!Continue) 3355 break; 3356 3357 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody()); 3358 if (ESR != ESR_Continue) 3359 return ESR; 3360 } 3361 return ESR_Succeeded; 3362 } 3363 3364 case Stmt::DoStmtClass: { 3365 const DoStmt *DS = cast<DoStmt>(S); 3366 bool Continue; 3367 do { 3368 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case); 3369 if (ESR != ESR_Continue) 3370 return ESR; 3371 Case = 0; 3372 3373 FullExpressionRAII CondScope(Info); 3374 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info)) 3375 return ESR_Failed; 3376 } while (Continue); 3377 return ESR_Succeeded; 3378 } 3379 3380 case Stmt::ForStmtClass: { 3381 const ForStmt *FS = cast<ForStmt>(S); 3382 BlockScopeRAII Scope(Info); 3383 if (FS->getInit()) { 3384 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); 3385 if (ESR != ESR_Succeeded) 3386 return ESR; 3387 } 3388 while (true) { 3389 BlockScopeRAII Scope(Info); 3390 bool Continue = true; 3391 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(), 3392 FS->getCond(), Continue)) 3393 return ESR_Failed; 3394 if (!Continue) 3395 break; 3396 3397 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody()); 3398 if (ESR != ESR_Continue) 3399 return ESR; 3400 3401 if (FS->getInc()) { 3402 FullExpressionRAII IncScope(Info); 3403 if (!EvaluateIgnoredValue(Info, FS->getInc())) 3404 return ESR_Failed; 3405 } 3406 } 3407 return ESR_Succeeded; 3408 } 3409 3410 case Stmt::CXXForRangeStmtClass: { 3411 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S); 3412 BlockScopeRAII Scope(Info); 3413 3414 // Initialize the __range variable. 3415 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt()); 3416 if (ESR != ESR_Succeeded) 3417 return ESR; 3418 3419 // Create the __begin and __end iterators. 3420 ESR = EvaluateStmt(Result, Info, FS->getBeginEndStmt()); 3421 if (ESR != ESR_Succeeded) 3422 return ESR; 3423 3424 while (true) { 3425 // Condition: __begin != __end. 3426 { 3427 bool Continue = true; 3428 FullExpressionRAII CondExpr(Info); 3429 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info)) 3430 return ESR_Failed; 3431 if (!Continue) 3432 break; 3433 } 3434 3435 // User's variable declaration, initialized by *__begin. 3436 BlockScopeRAII InnerScope(Info); 3437 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt()); 3438 if (ESR != ESR_Succeeded) 3439 return ESR; 3440 3441 // Loop body. 3442 ESR = EvaluateLoopBody(Result, Info, FS->getBody()); 3443 if (ESR != ESR_Continue) 3444 return ESR; 3445 3446 // Increment: ++__begin 3447 if (!EvaluateIgnoredValue(Info, FS->getInc())) 3448 return ESR_Failed; 3449 } 3450 3451 return ESR_Succeeded; 3452 } 3453 3454 case Stmt::SwitchStmtClass: 3455 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S)); 3456 3457 case Stmt::ContinueStmtClass: 3458 return ESR_Continue; 3459 3460 case Stmt::BreakStmtClass: 3461 return ESR_Break; 3462 3463 case Stmt::LabelStmtClass: 3464 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case); 3465 3466 case Stmt::AttributedStmtClass: 3467 // As a general principle, C++11 attributes can be ignored without 3468 // any semantic impact. 3469 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(), 3470 Case); 3471 3472 case Stmt::CaseStmtClass: 3473 case Stmt::DefaultStmtClass: 3474 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case); 3475 } 3476} 3477 3478/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial 3479/// default constructor. If so, we'll fold it whether or not it's marked as 3480/// constexpr. If it is marked as constexpr, we will never implicitly define it, 3481/// so we need special handling. 3482static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc, 3483 const CXXConstructorDecl *CD, 3484 bool IsValueInitialization) { 3485 if (!CD->isTrivial() || !CD->isDefaultConstructor()) 3486 return false; 3487 3488 // Value-initialization does not call a trivial default constructor, so such a 3489 // call is a core constant expression whether or not the constructor is 3490 // constexpr. 3491 if (!CD->isConstexpr() && !IsValueInitialization) { 3492 if (Info.getLangOpts().CPlusPlus11) { 3493 // FIXME: If DiagDecl is an implicitly-declared special member function, 3494 // we should be much more explicit about why it's not constexpr. 3495 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1) 3496 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD; 3497 Info.Note(CD->getLocation(), diag::note_declared_at); 3498 } else { 3499 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr); 3500 } 3501 } 3502 return true; 3503} 3504 3505/// CheckConstexprFunction - Check that a function can be called in a constant 3506/// expression. 3507static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc, 3508 const FunctionDecl *Declaration, 3509 const FunctionDecl *Definition) { 3510 // Potential constant expressions can contain calls to declared, but not yet 3511 // defined, constexpr functions. 3512 if (Info.checkingPotentialConstantExpression() && !Definition && 3513 Declaration->isConstexpr()) 3514 return false; 3515 3516 // Bail out with no diagnostic if the function declaration itself is invalid. 3517 // We will have produced a relevant diagnostic while parsing it. 3518 if (Declaration->isInvalidDecl()) 3519 return false; 3520 3521 // Can we evaluate this function call? 3522 if (Definition && Definition->isConstexpr() && !Definition->isInvalidDecl()) 3523 return true; 3524 3525 if (Info.getLangOpts().CPlusPlus11) { 3526 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration; 3527 // FIXME: If DiagDecl is an implicitly-declared special member function, we 3528 // should be much more explicit about why it's not constexpr. 3529 Info.Diag(CallLoc, diag::note_constexpr_invalid_function, 1) 3530 << DiagDecl->isConstexpr() << isa<CXXConstructorDecl>(DiagDecl) 3531 << DiagDecl; 3532 Info.Note(DiagDecl->getLocation(), diag::note_declared_at); 3533 } else { 3534 Info.Diag(CallLoc, diag::note_invalid_subexpr_in_const_expr); 3535 } 3536 return false; 3537} 3538 3539namespace { 3540typedef SmallVector<APValue, 8> ArgVector; 3541} 3542 3543/// EvaluateArgs - Evaluate the arguments to a function call. 3544static bool EvaluateArgs(ArrayRef<const Expr*> Args, ArgVector &ArgValues, 3545 EvalInfo &Info) { 3546 bool Success = true; 3547 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end(); 3548 I != E; ++I) { 3549 if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) { 3550 // If we're checking for a potential constant expression, evaluate all 3551 // initializers even if some of them fail. 3552 if (!Info.keepEvaluatingAfterFailure()) 3553 return false; 3554 Success = false; 3555 } 3556 } 3557 return Success; 3558} 3559 3560/// Evaluate a function call. 3561static bool HandleFunctionCall(SourceLocation CallLoc, 3562 const FunctionDecl *Callee, const LValue *This, 3563 ArrayRef<const Expr*> Args, const Stmt *Body, 3564 EvalInfo &Info, APValue &Result) { 3565 ArgVector ArgValues(Args.size()); 3566 if (!EvaluateArgs(Args, ArgValues, Info)) 3567 return false; 3568 3569 if (!Info.CheckCallLimit(CallLoc)) 3570 return false; 3571 3572 CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data()); 3573 3574 // For a trivial copy or move assignment, perform an APValue copy. This is 3575 // essential for unions, where the operations performed by the assignment 3576 // operator cannot be represented as statements. 3577 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee); 3578 if (MD && MD->isDefaulted() && MD->isTrivial()) { 3579 assert(This && 3580 (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())); 3581 LValue RHS; 3582 RHS.setFrom(Info.Ctx, ArgValues[0]); 3583 APValue RHSValue; 3584 if (!handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), 3585 RHS, RHSValue)) 3586 return false; 3587 if (!handleAssignment(Info, Args[0], *This, MD->getThisType(Info.Ctx), 3588 RHSValue)) 3589 return false; 3590 This->moveInto(Result); 3591 return true; 3592 } 3593 3594 EvalStmtResult ESR = EvaluateStmt(Result, Info, Body); 3595 if (ESR == ESR_Succeeded) { 3596 if (Callee->getResultType()->isVoidType()) 3597 return true; 3598 Info.Diag(Callee->getLocEnd(), diag::note_constexpr_no_return); 3599 } 3600 return ESR == ESR_Returned; 3601} 3602 3603/// Evaluate a constructor call. 3604static bool HandleConstructorCall(SourceLocation CallLoc, const LValue &This, 3605 ArrayRef<const Expr*> Args, 3606 const CXXConstructorDecl *Definition, 3607 EvalInfo &Info, APValue &Result) { 3608 ArgVector ArgValues(Args.size()); 3609 if (!EvaluateArgs(Args, ArgValues, Info)) 3610 return false; 3611 3612 if (!Info.CheckCallLimit(CallLoc)) 3613 return false; 3614 3615 const CXXRecordDecl *RD = Definition->getParent(); 3616 if (RD->getNumVBases()) { 3617 Info.Diag(CallLoc, diag::note_constexpr_virtual_base) << RD; 3618 return false; 3619 } 3620 3621 CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues.data()); 3622 3623 // If it's a delegating constructor, just delegate. 3624 if (Definition->isDelegatingConstructor()) { 3625 CXXConstructorDecl::init_const_iterator I = Definition->init_begin(); 3626 { 3627 FullExpressionRAII InitScope(Info); 3628 if (!EvaluateInPlace(Result, Info, This, (*I)->getInit())) 3629 return false; 3630 } 3631 return EvaluateStmt(Result, Info, Definition->getBody()) != ESR_Failed; 3632 } 3633 3634 // For a trivial copy or move constructor, perform an APValue copy. This is 3635 // essential for unions, where the operations performed by the constructor 3636 // cannot be represented by ctor-initializers. 3637 if (Definition->isDefaulted() && 3638 ((Definition->isCopyConstructor() && Definition->isTrivial()) || 3639 (Definition->isMoveConstructor() && Definition->isTrivial()))) { 3640 LValue RHS; 3641 RHS.setFrom(Info.Ctx, ArgValues[0]); 3642 return handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), 3643 RHS, Result); 3644 } 3645 3646 // Reserve space for the struct members. 3647 if (!RD->isUnion() && Result.isUninit()) 3648 Result = APValue(APValue::UninitStruct(), RD->getNumBases(), 3649 std::distance(RD->field_begin(), RD->field_end())); 3650 3651 if (RD->isInvalidDecl()) return false; 3652 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 3653 3654 // A scope for temporaries lifetime-extended by reference members. 3655 BlockScopeRAII LifetimeExtendedScope(Info); 3656 3657 bool Success = true; 3658 unsigned BasesSeen = 0; 3659#ifndef NDEBUG 3660 CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin(); 3661#endif 3662 for (CXXConstructorDecl::init_const_iterator I = Definition->init_begin(), 3663 E = Definition->init_end(); I != E; ++I) { 3664 LValue Subobject = This; 3665 APValue *Value = &Result; 3666 3667 // Determine the subobject to initialize. 3668 FieldDecl *FD = 0; 3669 if ((*I)->isBaseInitializer()) { 3670 QualType BaseType((*I)->getBaseClass(), 0); 3671#ifndef NDEBUG 3672 // Non-virtual base classes are initialized in the order in the class 3673 // definition. We have already checked for virtual base classes. 3674 assert(!BaseIt->isVirtual() && "virtual base for literal type"); 3675 assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && 3676 "base class initializers not in expected order"); 3677 ++BaseIt; 3678#endif 3679 if (!HandleLValueDirectBase(Info, (*I)->getInit(), Subobject, RD, 3680 BaseType->getAsCXXRecordDecl(), &Layout)) 3681 return false; 3682 Value = &Result.getStructBase(BasesSeen++); 3683 } else if ((FD = (*I)->getMember())) { 3684 if (!HandleLValueMember(Info, (*I)->getInit(), Subobject, FD, &Layout)) 3685 return false; 3686 if (RD->isUnion()) { 3687 Result = APValue(FD); 3688 Value = &Result.getUnionValue(); 3689 } else { 3690 Value = &Result.getStructField(FD->getFieldIndex()); 3691 } 3692 } else if (IndirectFieldDecl *IFD = (*I)->getIndirectMember()) { 3693 // Walk the indirect field decl's chain to find the object to initialize, 3694 // and make sure we've initialized every step along it. 3695 for (IndirectFieldDecl::chain_iterator C = IFD->chain_begin(), 3696 CE = IFD->chain_end(); 3697 C != CE; ++C) { 3698 FD = cast<FieldDecl>(*C); 3699 CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent()); 3700 // Switch the union field if it differs. This happens if we had 3701 // preceding zero-initialization, and we're now initializing a union 3702 // subobject other than the first. 3703 // FIXME: In this case, the values of the other subobjects are 3704 // specified, since zero-initialization sets all padding bits to zero. 3705 if (Value->isUninit() || 3706 (Value->isUnion() && Value->getUnionField() != FD)) { 3707 if (CD->isUnion()) 3708 *Value = APValue(FD); 3709 else 3710 *Value = APValue(APValue::UninitStruct(), CD->getNumBases(), 3711 std::distance(CD->field_begin(), CD->field_end())); 3712 } 3713 if (!HandleLValueMember(Info, (*I)->getInit(), Subobject, FD)) 3714 return false; 3715 if (CD->isUnion()) 3716 Value = &Value->getUnionValue(); 3717 else 3718 Value = &Value->getStructField(FD->getFieldIndex()); 3719 } 3720 } else { 3721 llvm_unreachable("unknown base initializer kind"); 3722 } 3723 3724 FullExpressionRAII InitScope(Info); 3725 if (!EvaluateInPlace(*Value, Info, Subobject, (*I)->getInit()) || 3726 (FD && FD->isBitField() && !truncateBitfieldValue(Info, (*I)->getInit(), 3727 *Value, FD))) { 3728 // If we're checking for a potential constant expression, evaluate all 3729 // initializers even if some of them fail. 3730 if (!Info.keepEvaluatingAfterFailure()) 3731 return false; 3732 Success = false; 3733 } 3734 } 3735 3736 return Success && 3737 EvaluateStmt(Result, Info, Definition->getBody()) != ESR_Failed; 3738} 3739 3740//===----------------------------------------------------------------------===// 3741// Generic Evaluation 3742//===----------------------------------------------------------------------===// 3743namespace { 3744 3745// FIXME: RetTy is always bool. Remove it. 3746template <class Derived, typename RetTy=bool> 3747class ExprEvaluatorBase 3748 : public ConstStmtVisitor<Derived, RetTy> { 3749private: 3750 RetTy DerivedSuccess(const APValue &V, const Expr *E) { 3751 return static_cast<Derived*>(this)->Success(V, E); 3752 } 3753 RetTy DerivedZeroInitialization(const Expr *E) { 3754 return static_cast<Derived*>(this)->ZeroInitialization(E); 3755 } 3756 3757 // Check whether a conditional operator with a non-constant condition is a 3758 // potential constant expression. If neither arm is a potential constant 3759 // expression, then the conditional operator is not either. 3760 template<typename ConditionalOperator> 3761 void CheckPotentialConstantConditional(const ConditionalOperator *E) { 3762 assert(Info.checkingPotentialConstantExpression()); 3763 3764 // Speculatively evaluate both arms. 3765 { 3766 SmallVector<PartialDiagnosticAt, 8> Diag; 3767 SpeculativeEvaluationRAII Speculate(Info, &Diag); 3768 3769 StmtVisitorTy::Visit(E->getFalseExpr()); 3770 if (Diag.empty()) 3771 return; 3772 3773 Diag.clear(); 3774 StmtVisitorTy::Visit(E->getTrueExpr()); 3775 if (Diag.empty()) 3776 return; 3777 } 3778 3779 Error(E, diag::note_constexpr_conditional_never_const); 3780 } 3781 3782 3783 template<typename ConditionalOperator> 3784 bool HandleConditionalOperator(const ConditionalOperator *E) { 3785 bool BoolResult; 3786 if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) { 3787 if (Info.checkingPotentialConstantExpression()) 3788 CheckPotentialConstantConditional(E); 3789 return false; 3790 } 3791 3792 Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr(); 3793 return StmtVisitorTy::Visit(EvalExpr); 3794 } 3795 3796protected: 3797 EvalInfo &Info; 3798 typedef ConstStmtVisitor<Derived, RetTy> StmtVisitorTy; 3799 typedef ExprEvaluatorBase ExprEvaluatorBaseTy; 3800 3801 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { 3802 return Info.CCEDiag(E, D); 3803 } 3804 3805 RetTy ZeroInitialization(const Expr *E) { return Error(E); } 3806 3807public: 3808 ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {} 3809 3810 EvalInfo &getEvalInfo() { return Info; } 3811 3812 /// Report an evaluation error. This should only be called when an error is 3813 /// first discovered. When propagating an error, just return false. 3814 bool Error(const Expr *E, diag::kind D) { 3815 Info.Diag(E, D); 3816 return false; 3817 } 3818 bool Error(const Expr *E) { 3819 return Error(E, diag::note_invalid_subexpr_in_const_expr); 3820 } 3821 3822 RetTy VisitStmt(const Stmt *) { 3823 llvm_unreachable("Expression evaluator should not be called on stmts"); 3824 } 3825 RetTy VisitExpr(const Expr *E) { 3826 return Error(E); 3827 } 3828 3829 RetTy VisitParenExpr(const ParenExpr *E) 3830 { return StmtVisitorTy::Visit(E->getSubExpr()); } 3831 RetTy VisitUnaryExtension(const UnaryOperator *E) 3832 { return StmtVisitorTy::Visit(E->getSubExpr()); } 3833 RetTy VisitUnaryPlus(const UnaryOperator *E) 3834 { return StmtVisitorTy::Visit(E->getSubExpr()); } 3835 RetTy VisitChooseExpr(const ChooseExpr *E) 3836 { return StmtVisitorTy::Visit(E->getChosenSubExpr()); } 3837 RetTy VisitGenericSelectionExpr(const GenericSelectionExpr *E) 3838 { return StmtVisitorTy::Visit(E->getResultExpr()); } 3839 RetTy VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E) 3840 { return StmtVisitorTy::Visit(E->getReplacement()); } 3841 RetTy VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) 3842 { return StmtVisitorTy::Visit(E->getExpr()); } 3843 RetTy VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) { 3844 // The initializer may not have been parsed yet, or might be erroneous. 3845 if (!E->getExpr()) 3846 return Error(E); 3847 return StmtVisitorTy::Visit(E->getExpr()); 3848 } 3849 // We cannot create any objects for which cleanups are required, so there is 3850 // nothing to do here; all cleanups must come from unevaluated subexpressions. 3851 RetTy VisitExprWithCleanups(const ExprWithCleanups *E) 3852 { return StmtVisitorTy::Visit(E->getSubExpr()); } 3853 3854 RetTy VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) { 3855 CCEDiag(E, diag::note_constexpr_invalid_cast) << 0; 3856 return static_cast<Derived*>(this)->VisitCastExpr(E); 3857 } 3858 RetTy VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) { 3859 CCEDiag(E, diag::note_constexpr_invalid_cast) << 1; 3860 return static_cast<Derived*>(this)->VisitCastExpr(E); 3861 } 3862 3863 RetTy VisitBinaryOperator(const BinaryOperator *E) { 3864 switch (E->getOpcode()) { 3865 default: 3866 return Error(E); 3867 3868 case BO_Comma: 3869 VisitIgnoredValue(E->getLHS()); 3870 return StmtVisitorTy::Visit(E->getRHS()); 3871 3872 case BO_PtrMemD: 3873 case BO_PtrMemI: { 3874 LValue Obj; 3875 if (!HandleMemberPointerAccess(Info, E, Obj)) 3876 return false; 3877 APValue Result; 3878 if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result)) 3879 return false; 3880 return DerivedSuccess(Result, E); 3881 } 3882 } 3883 } 3884 3885 RetTy VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) { 3886 // Evaluate and cache the common expression. We treat it as a temporary, 3887 // even though it's not quite the same thing. 3888 if (!Evaluate(Info.CurrentCall->createTemporary(E->getOpaqueValue(), false), 3889 Info, E->getCommon())) 3890 return false; 3891 3892 return HandleConditionalOperator(E); 3893 } 3894 3895 RetTy VisitConditionalOperator(const ConditionalOperator *E) { 3896 bool IsBcpCall = false; 3897 // If the condition (ignoring parens) is a __builtin_constant_p call, 3898 // the result is a constant expression if it can be folded without 3899 // side-effects. This is an important GNU extension. See GCC PR38377 3900 // for discussion. 3901 if (const CallExpr *CallCE = 3902 dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts())) 3903 if (CallCE->isBuiltinCall() == Builtin::BI__builtin_constant_p) 3904 IsBcpCall = true; 3905 3906 // Always assume __builtin_constant_p(...) ? ... : ... is a potential 3907 // constant expression; we can't check whether it's potentially foldable. 3908 if (Info.checkingPotentialConstantExpression() && IsBcpCall) 3909 return false; 3910 3911 FoldConstant Fold(Info, IsBcpCall); 3912 if (!HandleConditionalOperator(E)) { 3913 Fold.keepDiagnostics(); 3914 return false; 3915 } 3916 3917 return true; 3918 } 3919 3920 RetTy VisitOpaqueValueExpr(const OpaqueValueExpr *E) { 3921 if (APValue *Value = Info.CurrentCall->getTemporary(E)) 3922 return DerivedSuccess(*Value, E); 3923 3924 const Expr *Source = E->getSourceExpr(); 3925 if (!Source) 3926 return Error(E); 3927 if (Source == E) { // sanity checking. 3928 assert(0 && "OpaqueValueExpr recursively refers to itself"); 3929 return Error(E); 3930 } 3931 return StmtVisitorTy::Visit(Source); 3932 } 3933 3934 RetTy VisitCallExpr(const CallExpr *E) { 3935 const Expr *Callee = E->getCallee()->IgnoreParens(); 3936 QualType CalleeType = Callee->getType(); 3937 3938 const FunctionDecl *FD = 0; 3939 LValue *This = 0, ThisVal; 3940 ArrayRef<const Expr *> Args(E->getArgs(), E->getNumArgs()); 3941 bool HasQualifier = false; 3942 3943 // Extract function decl and 'this' pointer from the callee. 3944 if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) { 3945 const ValueDecl *Member = 0; 3946 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) { 3947 // Explicit bound member calls, such as x.f() or p->g(); 3948 if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal)) 3949 return false; 3950 Member = ME->getMemberDecl(); 3951 This = &ThisVal; 3952 HasQualifier = ME->hasQualifier(); 3953 } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) { 3954 // Indirect bound member calls ('.*' or '->*'). 3955 Member = HandleMemberPointerAccess(Info, BE, ThisVal, false); 3956 if (!Member) return false; 3957 This = &ThisVal; 3958 } else 3959 return Error(Callee); 3960 3961 FD = dyn_cast<FunctionDecl>(Member); 3962 if (!FD) 3963 return Error(Callee); 3964 } else if (CalleeType->isFunctionPointerType()) { 3965 LValue Call; 3966 if (!EvaluatePointer(Callee, Call, Info)) 3967 return false; 3968 3969 if (!Call.getLValueOffset().isZero()) 3970 return Error(Callee); 3971 FD = dyn_cast_or_null<FunctionDecl>( 3972 Call.getLValueBase().dyn_cast<const ValueDecl*>()); 3973 if (!FD) 3974 return Error(Callee); 3975 3976 // Overloaded operator calls to member functions are represented as normal 3977 // calls with '*this' as the first argument. 3978 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); 3979 if (MD && !MD->isStatic()) { 3980 // FIXME: When selecting an implicit conversion for an overloaded 3981 // operator delete, we sometimes try to evaluate calls to conversion 3982 // operators without a 'this' parameter! 3983 if (Args.empty()) 3984 return Error(E); 3985 3986 if (!EvaluateObjectArgument(Info, Args[0], ThisVal)) 3987 return false; 3988 This = &ThisVal; 3989 Args = Args.slice(1); 3990 } 3991 3992 // Don't call function pointers which have been cast to some other type. 3993 if (!Info.Ctx.hasSameType(CalleeType->getPointeeType(), FD->getType())) 3994 return Error(E); 3995 } else 3996 return Error(E); 3997 3998 if (This && !This->checkSubobject(Info, E, CSK_This)) 3999 return false; 4000 4001 // DR1358 allows virtual constexpr functions in some cases. Don't allow 4002 // calls to such functions in constant expressions. 4003 if (This && !HasQualifier && 4004 isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isVirtual()) 4005 return Error(E, diag::note_constexpr_virtual_call); 4006 4007 const FunctionDecl *Definition = 0; 4008 Stmt *Body = FD->getBody(Definition); 4009 APValue Result; 4010 4011 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition) || 4012 !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, 4013 Info, Result)) 4014 return false; 4015 4016 return DerivedSuccess(Result, E); 4017 } 4018 4019 RetTy VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { 4020 return StmtVisitorTy::Visit(E->getInitializer()); 4021 } 4022 RetTy VisitInitListExpr(const InitListExpr *E) { 4023 if (E->getNumInits() == 0) 4024 return DerivedZeroInitialization(E); 4025 if (E->getNumInits() == 1) 4026 return StmtVisitorTy::Visit(E->getInit(0)); 4027 return Error(E); 4028 } 4029 RetTy VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) { 4030 return DerivedZeroInitialization(E); 4031 } 4032 RetTy VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) { 4033 return DerivedZeroInitialization(E); 4034 } 4035 RetTy VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) { 4036 return DerivedZeroInitialization(E); 4037 } 4038 4039 /// A member expression where the object is a prvalue is itself a prvalue. 4040 RetTy VisitMemberExpr(const MemberExpr *E) { 4041 assert(!E->isArrow() && "missing call to bound member function?"); 4042 4043 APValue Val; 4044 if (!Evaluate(Val, Info, E->getBase())) 4045 return false; 4046 4047 QualType BaseTy = E->getBase()->getType(); 4048 4049 const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl()); 4050 if (!FD) return Error(E); 4051 assert(!FD->getType()->isReferenceType() && "prvalue reference?"); 4052 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == 4053 FD->getParent()->getCanonicalDecl() && "record / field mismatch"); 4054 4055 CompleteObject Obj(&Val, BaseTy); 4056 SubobjectDesignator Designator(BaseTy); 4057 Designator.addDeclUnchecked(FD); 4058 4059 APValue Result; 4060 return extractSubobject(Info, E, Obj, Designator, Result) && 4061 DerivedSuccess(Result, E); 4062 } 4063 4064 RetTy VisitCastExpr(const CastExpr *E) { 4065 switch (E->getCastKind()) { 4066 default: 4067 break; 4068 4069 case CK_AtomicToNonAtomic: { 4070 APValue AtomicVal; 4071 if (!EvaluateAtomic(E->getSubExpr(), AtomicVal, Info)) 4072 return false; 4073 return DerivedSuccess(AtomicVal, E); 4074 } 4075 4076 case CK_NoOp: 4077 case CK_UserDefinedConversion: 4078 return StmtVisitorTy::Visit(E->getSubExpr()); 4079 4080 case CK_LValueToRValue: { 4081 LValue LVal; 4082 if (!EvaluateLValue(E->getSubExpr(), LVal, Info)) 4083 return false; 4084 APValue RVal; 4085 // Note, we use the subexpression's type in order to retain cv-qualifiers. 4086 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(), 4087 LVal, RVal)) 4088 return false; 4089 return DerivedSuccess(RVal, E); 4090 } 4091 } 4092 4093 return Error(E); 4094 } 4095 4096 RetTy VisitUnaryPostInc(const UnaryOperator *UO) { 4097 return VisitUnaryPostIncDec(UO); 4098 } 4099 RetTy VisitUnaryPostDec(const UnaryOperator *UO) { 4100 return VisitUnaryPostIncDec(UO); 4101 } 4102 RetTy VisitUnaryPostIncDec(const UnaryOperator *UO) { 4103 if (!Info.getLangOpts().CPlusPlus1y && !Info.keepEvaluatingAfterFailure()) 4104 return Error(UO); 4105 4106 LValue LVal; 4107 if (!EvaluateLValue(UO->getSubExpr(), LVal, Info)) 4108 return false; 4109 APValue RVal; 4110 if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(), 4111 UO->isIncrementOp(), &RVal)) 4112 return false; 4113 return DerivedSuccess(RVal, UO); 4114 } 4115 4116 RetTy VisitStmtExpr(const StmtExpr *E) { 4117 // We will have checked the full-expressions inside the statement expression 4118 // when they were completed, and don't need to check them again now. 4119 if (Info.checkingForOverflow()) 4120 return Error(E); 4121 4122 BlockScopeRAII Scope(Info); 4123 const CompoundStmt *CS = E->getSubStmt(); 4124 for (CompoundStmt::const_body_iterator BI = CS->body_begin(), 4125 BE = CS->body_end(); 4126 /**/; ++BI) { 4127 if (BI + 1 == BE) { 4128 const Expr *FinalExpr = dyn_cast<Expr>(*BI); 4129 if (!FinalExpr) { 4130 Info.Diag((*BI)->getLocStart(), 4131 diag::note_constexpr_stmt_expr_unsupported); 4132 return false; 4133 } 4134 return this->Visit(FinalExpr); 4135 } 4136 4137 APValue ReturnValue; 4138 EvalStmtResult ESR = EvaluateStmt(ReturnValue, Info, *BI); 4139 if (ESR != ESR_Succeeded) { 4140 // FIXME: If the statement-expression terminated due to 'return', 4141 // 'break', or 'continue', it would be nice to propagate that to 4142 // the outer statement evaluation rather than bailing out. 4143 if (ESR != ESR_Failed) 4144 Info.Diag((*BI)->getLocStart(), 4145 diag::note_constexpr_stmt_expr_unsupported); 4146 return false; 4147 } 4148 } 4149 } 4150 4151 /// Visit a value which is evaluated, but whose value is ignored. 4152 void VisitIgnoredValue(const Expr *E) { 4153 EvaluateIgnoredValue(Info, E); 4154 } 4155}; 4156 4157} 4158 4159//===----------------------------------------------------------------------===// 4160// Common base class for lvalue and temporary evaluation. 4161//===----------------------------------------------------------------------===// 4162namespace { 4163template<class Derived> 4164class LValueExprEvaluatorBase 4165 : public ExprEvaluatorBase<Derived, bool> { 4166protected: 4167 LValue &Result; 4168 typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy; 4169 typedef ExprEvaluatorBase<Derived, bool> ExprEvaluatorBaseTy; 4170 4171 bool Success(APValue::LValueBase B) { 4172 Result.set(B); 4173 return true; 4174 } 4175 4176public: 4177 LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result) : 4178 ExprEvaluatorBaseTy(Info), Result(Result) {} 4179 4180 bool Success(const APValue &V, const Expr *E) { 4181 Result.setFrom(this->Info.Ctx, V); 4182 return true; 4183 } 4184 4185 bool VisitMemberExpr(const MemberExpr *E) { 4186 // Handle non-static data members. 4187 QualType BaseTy; 4188 if (E->isArrow()) { 4189 if (!EvaluatePointer(E->getBase(), Result, this->Info)) 4190 return false; 4191 BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType(); 4192 } else if (E->getBase()->isRValue()) { 4193 assert(E->getBase()->getType()->isRecordType()); 4194 if (!EvaluateTemporary(E->getBase(), Result, this->Info)) 4195 return false; 4196 BaseTy = E->getBase()->getType(); 4197 } else { 4198 if (!this->Visit(E->getBase())) 4199 return false; 4200 BaseTy = E->getBase()->getType(); 4201 } 4202 4203 const ValueDecl *MD = E->getMemberDecl(); 4204 if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) { 4205 assert(BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() == 4206 FD->getParent()->getCanonicalDecl() && "record / field mismatch"); 4207 (void)BaseTy; 4208 if (!HandleLValueMember(this->Info, E, Result, FD)) 4209 return false; 4210 } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) { 4211 if (!HandleLValueIndirectMember(this->Info, E, Result, IFD)) 4212 return false; 4213 } else 4214 return this->Error(E); 4215 4216 if (MD->getType()->isReferenceType()) { 4217 APValue RefValue; 4218 if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result, 4219 RefValue)) 4220 return false; 4221 return Success(RefValue, E); 4222 } 4223 return true; 4224 } 4225 4226 bool VisitBinaryOperator(const BinaryOperator *E) { 4227 switch (E->getOpcode()) { 4228 default: 4229 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 4230 4231 case BO_PtrMemD: 4232 case BO_PtrMemI: 4233 return HandleMemberPointerAccess(this->Info, E, Result); 4234 } 4235 } 4236 4237 bool VisitCastExpr(const CastExpr *E) { 4238 switch (E->getCastKind()) { 4239 default: 4240 return ExprEvaluatorBaseTy::VisitCastExpr(E); 4241 4242 case CK_DerivedToBase: 4243 case CK_UncheckedDerivedToBase: 4244 if (!this->Visit(E->getSubExpr())) 4245 return false; 4246 4247 // Now figure out the necessary offset to add to the base LV to get from 4248 // the derived class to the base class. 4249 return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(), 4250 Result); 4251 } 4252 } 4253}; 4254} 4255 4256//===----------------------------------------------------------------------===// 4257// LValue Evaluation 4258// 4259// This is used for evaluating lvalues (in C and C++), xvalues (in C++11), 4260// function designators (in C), decl references to void objects (in C), and 4261// temporaries (if building with -Wno-address-of-temporary). 4262// 4263// LValue evaluation produces values comprising a base expression of one of the 4264// following types: 4265// - Declarations 4266// * VarDecl 4267// * FunctionDecl 4268// - Literals 4269// * CompoundLiteralExpr in C 4270// * StringLiteral 4271// * CXXTypeidExpr 4272// * PredefinedExpr 4273// * ObjCStringLiteralExpr 4274// * ObjCEncodeExpr 4275// * AddrLabelExpr 4276// * BlockExpr 4277// * CallExpr for a MakeStringConstant builtin 4278// - Locals and temporaries 4279// * MaterializeTemporaryExpr 4280// * Any Expr, with a CallIndex indicating the function in which the temporary 4281// was evaluated, for cases where the MaterializeTemporaryExpr is missing 4282// from the AST (FIXME). 4283// * A MaterializeTemporaryExpr that has static storage duration, with no 4284// CallIndex, for a lifetime-extended temporary. 4285// plus an offset in bytes. 4286//===----------------------------------------------------------------------===// 4287namespace { 4288class LValueExprEvaluator 4289 : public LValueExprEvaluatorBase<LValueExprEvaluator> { 4290public: 4291 LValueExprEvaluator(EvalInfo &Info, LValue &Result) : 4292 LValueExprEvaluatorBaseTy(Info, Result) {} 4293 4294 bool VisitVarDecl(const Expr *E, const VarDecl *VD); 4295 bool VisitUnaryPreIncDec(const UnaryOperator *UO); 4296 4297 bool VisitDeclRefExpr(const DeclRefExpr *E); 4298 bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); } 4299 bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E); 4300 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E); 4301 bool VisitMemberExpr(const MemberExpr *E); 4302 bool VisitStringLiteral(const StringLiteral *E) { return Success(E); } 4303 bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); } 4304 bool VisitCXXTypeidExpr(const CXXTypeidExpr *E); 4305 bool VisitCXXUuidofExpr(const CXXUuidofExpr *E); 4306 bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E); 4307 bool VisitUnaryDeref(const UnaryOperator *E); 4308 bool VisitUnaryReal(const UnaryOperator *E); 4309 bool VisitUnaryImag(const UnaryOperator *E); 4310 bool VisitUnaryPreInc(const UnaryOperator *UO) { 4311 return VisitUnaryPreIncDec(UO); 4312 } 4313 bool VisitUnaryPreDec(const UnaryOperator *UO) { 4314 return VisitUnaryPreIncDec(UO); 4315 } 4316 bool VisitBinAssign(const BinaryOperator *BO); 4317 bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO); 4318 4319 bool VisitCastExpr(const CastExpr *E) { 4320 switch (E->getCastKind()) { 4321 default: 4322 return LValueExprEvaluatorBaseTy::VisitCastExpr(E); 4323 4324 case CK_LValueBitCast: 4325 this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 4326 if (!Visit(E->getSubExpr())) 4327 return false; 4328 Result.Designator.setInvalid(); 4329 return true; 4330 4331 case CK_BaseToDerived: 4332 if (!Visit(E->getSubExpr())) 4333 return false; 4334 return HandleBaseToDerivedCast(Info, E, Result); 4335 } 4336 } 4337}; 4338} // end anonymous namespace 4339 4340/// Evaluate an expression as an lvalue. This can be legitimately called on 4341/// expressions which are not glvalues, in two cases: 4342/// * function designators in C, and 4343/// * "extern void" objects 4344static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info) { 4345 assert(E->isGLValue() || E->getType()->isFunctionType() || 4346 E->getType()->isVoidType()); 4347 return LValueExprEvaluator(Info, Result).Visit(E); 4348} 4349 4350bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) { 4351 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl())) 4352 return Success(FD); 4353 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl())) 4354 return VisitVarDecl(E, VD); 4355 return Error(E); 4356} 4357 4358bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) { 4359 CallStackFrame *Frame = 0; 4360 if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) 4361 Frame = Info.CurrentCall; 4362 4363 if (!VD->getType()->isReferenceType()) { 4364 if (Frame) { 4365 Result.set(VD, Frame->Index); 4366 return true; 4367 } 4368 return Success(VD); 4369 } 4370 4371 APValue *V; 4372 if (!evaluateVarDeclInit(Info, E, VD, Frame, V)) 4373 return false; 4374 if (V->isUninit()) { 4375 if (!Info.checkingPotentialConstantExpression()) 4376 Info.Diag(E, diag::note_constexpr_use_uninit_reference); 4377 return false; 4378 } 4379 return Success(*V, E); 4380} 4381 4382bool LValueExprEvaluator::VisitMaterializeTemporaryExpr( 4383 const MaterializeTemporaryExpr *E) { 4384 // Walk through the expression to find the materialized temporary itself. 4385 SmallVector<const Expr *, 2> CommaLHSs; 4386 SmallVector<SubobjectAdjustment, 2> Adjustments; 4387 const Expr *Inner = E->GetTemporaryExpr()-> 4388 skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); 4389 4390 // If we passed any comma operators, evaluate their LHSs. 4391 for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I) 4392 if (!EvaluateIgnoredValue(Info, CommaLHSs[I])) 4393 return false; 4394 4395 // A materialized temporary with static storage duration can appear within the 4396 // result of a constant expression evaluation, so we need to preserve its 4397 // value for use outside this evaluation. 4398 APValue *Value; 4399 if (E->getStorageDuration() == SD_Static) { 4400 Value = Info.Ctx.getMaterializedTemporaryValue(E, true); 4401 *Value = APValue(); 4402 Result.set(E); 4403 } else { 4404 Value = &Info.CurrentCall-> 4405 createTemporary(E, E->getStorageDuration() == SD_Automatic); 4406 Result.set(E, Info.CurrentCall->Index); 4407 } 4408 4409 QualType Type = Inner->getType(); 4410 4411 // Materialize the temporary itself. 4412 if (!EvaluateInPlace(*Value, Info, Result, Inner) || 4413 (E->getStorageDuration() == SD_Static && 4414 !CheckConstantExpression(Info, E->getExprLoc(), Type, *Value))) { 4415 *Value = APValue(); 4416 return false; 4417 } 4418 4419 // Adjust our lvalue to refer to the desired subobject. 4420 for (unsigned I = Adjustments.size(); I != 0; /**/) { 4421 --I; 4422 switch (Adjustments[I].Kind) { 4423 case SubobjectAdjustment::DerivedToBaseAdjustment: 4424 if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath, 4425 Type, Result)) 4426 return false; 4427 Type = Adjustments[I].DerivedToBase.BasePath->getType(); 4428 break; 4429 4430 case SubobjectAdjustment::FieldAdjustment: 4431 if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field)) 4432 return false; 4433 Type = Adjustments[I].Field->getType(); 4434 break; 4435 4436 case SubobjectAdjustment::MemberPointerAdjustment: 4437 if (!HandleMemberPointerAccess(this->Info, Type, Result, 4438 Adjustments[I].Ptr.RHS)) 4439 return false; 4440 Type = Adjustments[I].Ptr.MPT->getPointeeType(); 4441 break; 4442 } 4443 } 4444 4445 return true; 4446} 4447 4448bool 4449LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { 4450 assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?"); 4451 // Defer visiting the literal until the lvalue-to-rvalue conversion. We can 4452 // only see this when folding in C, so there's no standard to follow here. 4453 return Success(E); 4454} 4455 4456bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) { 4457 if (!E->isPotentiallyEvaluated()) 4458 return Success(E); 4459 4460 Info.Diag(E, diag::note_constexpr_typeid_polymorphic) 4461 << E->getExprOperand()->getType() 4462 << E->getExprOperand()->getSourceRange(); 4463 return false; 4464} 4465 4466bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) { 4467 return Success(E); 4468} 4469 4470bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) { 4471 // Handle static data members. 4472 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) { 4473 VisitIgnoredValue(E->getBase()); 4474 return VisitVarDecl(E, VD); 4475 } 4476 4477 // Handle static member functions. 4478 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) { 4479 if (MD->isStatic()) { 4480 VisitIgnoredValue(E->getBase()); 4481 return Success(MD); 4482 } 4483 } 4484 4485 // Handle non-static data members. 4486 return LValueExprEvaluatorBaseTy::VisitMemberExpr(E); 4487} 4488 4489bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) { 4490 // FIXME: Deal with vectors as array subscript bases. 4491 if (E->getBase()->getType()->isVectorType()) 4492 return Error(E); 4493 4494 if (!EvaluatePointer(E->getBase(), Result, Info)) 4495 return false; 4496 4497 APSInt Index; 4498 if (!EvaluateInteger(E->getIdx(), Index, Info)) 4499 return false; 4500 4501 return HandleLValueArrayAdjustment(Info, E, Result, E->getType(), 4502 getExtValue(Index)); 4503} 4504 4505bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) { 4506 return EvaluatePointer(E->getSubExpr(), Result, Info); 4507} 4508 4509bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 4510 if (!Visit(E->getSubExpr())) 4511 return false; 4512 // __real is a no-op on scalar lvalues. 4513 if (E->getSubExpr()->getType()->isAnyComplexType()) 4514 HandleLValueComplexElement(Info, E, Result, E->getType(), false); 4515 return true; 4516} 4517 4518bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 4519 assert(E->getSubExpr()->getType()->isAnyComplexType() && 4520 "lvalue __imag__ on scalar?"); 4521 if (!Visit(E->getSubExpr())) 4522 return false; 4523 HandleLValueComplexElement(Info, E, Result, E->getType(), true); 4524 return true; 4525} 4526 4527bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) { 4528 if (!Info.getLangOpts().CPlusPlus1y && !Info.keepEvaluatingAfterFailure()) 4529 return Error(UO); 4530 4531 if (!this->Visit(UO->getSubExpr())) 4532 return false; 4533 4534 return handleIncDec( 4535 this->Info, UO, Result, UO->getSubExpr()->getType(), 4536 UO->isIncrementOp(), 0); 4537} 4538 4539bool LValueExprEvaluator::VisitCompoundAssignOperator( 4540 const CompoundAssignOperator *CAO) { 4541 if (!Info.getLangOpts().CPlusPlus1y && !Info.keepEvaluatingAfterFailure()) 4542 return Error(CAO); 4543 4544 APValue RHS; 4545 4546 // The overall lvalue result is the result of evaluating the LHS. 4547 if (!this->Visit(CAO->getLHS())) { 4548 if (Info.keepEvaluatingAfterFailure()) 4549 Evaluate(RHS, this->Info, CAO->getRHS()); 4550 return false; 4551 } 4552 4553 if (!Evaluate(RHS, this->Info, CAO->getRHS())) 4554 return false; 4555 4556 return handleCompoundAssignment( 4557 this->Info, CAO, 4558 Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(), 4559 CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS); 4560} 4561 4562bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) { 4563 if (!Info.getLangOpts().CPlusPlus1y && !Info.keepEvaluatingAfterFailure()) 4564 return Error(E); 4565 4566 APValue NewVal; 4567 4568 if (!this->Visit(E->getLHS())) { 4569 if (Info.keepEvaluatingAfterFailure()) 4570 Evaluate(NewVal, this->Info, E->getRHS()); 4571 return false; 4572 } 4573 4574 if (!Evaluate(NewVal, this->Info, E->getRHS())) 4575 return false; 4576 4577 return handleAssignment(this->Info, E, Result, E->getLHS()->getType(), 4578 NewVal); 4579} 4580 4581//===----------------------------------------------------------------------===// 4582// Pointer Evaluation 4583//===----------------------------------------------------------------------===// 4584 4585namespace { 4586class PointerExprEvaluator 4587 : public ExprEvaluatorBase<PointerExprEvaluator, bool> { 4588 LValue &Result; 4589 4590 bool Success(const Expr *E) { 4591 Result.set(E); 4592 return true; 4593 } 4594public: 4595 4596 PointerExprEvaluator(EvalInfo &info, LValue &Result) 4597 : ExprEvaluatorBaseTy(info), Result(Result) {} 4598 4599 bool Success(const APValue &V, const Expr *E) { 4600 Result.setFrom(Info.Ctx, V); 4601 return true; 4602 } 4603 bool ZeroInitialization(const Expr *E) { 4604 return Success((Expr*)0); 4605 } 4606 4607 bool VisitBinaryOperator(const BinaryOperator *E); 4608 bool VisitCastExpr(const CastExpr* E); 4609 bool VisitUnaryAddrOf(const UnaryOperator *E); 4610 bool VisitObjCStringLiteral(const ObjCStringLiteral *E) 4611 { return Success(E); } 4612 bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) 4613 { return Success(E); } 4614 bool VisitAddrLabelExpr(const AddrLabelExpr *E) 4615 { return Success(E); } 4616 bool VisitCallExpr(const CallExpr *E); 4617 bool VisitBlockExpr(const BlockExpr *E) { 4618 if (!E->getBlockDecl()->hasCaptures()) 4619 return Success(E); 4620 return Error(E); 4621 } 4622 bool VisitCXXThisExpr(const CXXThisExpr *E) { 4623 // Can't look at 'this' when checking a potential constant expression. 4624 if (Info.checkingPotentialConstantExpression()) 4625 return false; 4626 if (!Info.CurrentCall->This) 4627 return Error(E); 4628 Result = *Info.CurrentCall->This; 4629 return true; 4630 } 4631 4632 // FIXME: Missing: @protocol, @selector 4633}; 4634} // end anonymous namespace 4635 4636static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info) { 4637 assert(E->isRValue() && E->getType()->hasPointerRepresentation()); 4638 return PointerExprEvaluator(Info, Result).Visit(E); 4639} 4640 4641bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 4642 if (E->getOpcode() != BO_Add && 4643 E->getOpcode() != BO_Sub) 4644 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 4645 4646 const Expr *PExp = E->getLHS(); 4647 const Expr *IExp = E->getRHS(); 4648 if (IExp->getType()->isPointerType()) 4649 std::swap(PExp, IExp); 4650 4651 bool EvalPtrOK = EvaluatePointer(PExp, Result, Info); 4652 if (!EvalPtrOK && !Info.keepEvaluatingAfterFailure()) 4653 return false; 4654 4655 llvm::APSInt Offset; 4656 if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK) 4657 return false; 4658 4659 int64_t AdditionalOffset = getExtValue(Offset); 4660 if (E->getOpcode() == BO_Sub) 4661 AdditionalOffset = -AdditionalOffset; 4662 4663 QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType(); 4664 return HandleLValueArrayAdjustment(Info, E, Result, Pointee, 4665 AdditionalOffset); 4666} 4667 4668bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { 4669 return EvaluateLValue(E->getSubExpr(), Result, Info); 4670} 4671 4672bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) { 4673 const Expr* SubExpr = E->getSubExpr(); 4674 4675 switch (E->getCastKind()) { 4676 default: 4677 break; 4678 4679 case CK_BitCast: 4680 case CK_CPointerToObjCPointerCast: 4681 case CK_BlockPointerToObjCPointerCast: 4682 case CK_AnyPointerToBlockPointerCast: 4683 if (!Visit(SubExpr)) 4684 return false; 4685 // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are 4686 // permitted in constant expressions in C++11. Bitcasts from cv void* are 4687 // also static_casts, but we disallow them as a resolution to DR1312. 4688 if (!E->getType()->isVoidPointerType()) { 4689 Result.Designator.setInvalid(); 4690 if (SubExpr->getType()->isVoidPointerType()) 4691 CCEDiag(E, diag::note_constexpr_invalid_cast) 4692 << 3 << SubExpr->getType(); 4693 else 4694 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 4695 } 4696 return true; 4697 4698 case CK_DerivedToBase: 4699 case CK_UncheckedDerivedToBase: 4700 if (!EvaluatePointer(E->getSubExpr(), Result, Info)) 4701 return false; 4702 if (!Result.Base && Result.Offset.isZero()) 4703 return true; 4704 4705 // Now figure out the necessary offset to add to the base LV to get from 4706 // the derived class to the base class. 4707 return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()-> 4708 castAs<PointerType>()->getPointeeType(), 4709 Result); 4710 4711 case CK_BaseToDerived: 4712 if (!Visit(E->getSubExpr())) 4713 return false; 4714 if (!Result.Base && Result.Offset.isZero()) 4715 return true; 4716 return HandleBaseToDerivedCast(Info, E, Result); 4717 4718 case CK_NullToPointer: 4719 VisitIgnoredValue(E->getSubExpr()); 4720 return ZeroInitialization(E); 4721 4722 case CK_IntegralToPointer: { 4723 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 4724 4725 APValue Value; 4726 if (!EvaluateIntegerOrLValue(SubExpr, Value, Info)) 4727 break; 4728 4729 if (Value.isInt()) { 4730 unsigned Size = Info.Ctx.getTypeSize(E->getType()); 4731 uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue(); 4732 Result.Base = (Expr*)0; 4733 Result.Offset = CharUnits::fromQuantity(N); 4734 Result.CallIndex = 0; 4735 Result.Designator.setInvalid(); 4736 return true; 4737 } else { 4738 // Cast is of an lvalue, no need to change value. 4739 Result.setFrom(Info.Ctx, Value); 4740 return true; 4741 } 4742 } 4743 case CK_ArrayToPointerDecay: 4744 if (SubExpr->isGLValue()) { 4745 if (!EvaluateLValue(SubExpr, Result, Info)) 4746 return false; 4747 } else { 4748 Result.set(SubExpr, Info.CurrentCall->Index); 4749 if (!EvaluateInPlace(Info.CurrentCall->createTemporary(SubExpr, false), 4750 Info, Result, SubExpr)) 4751 return false; 4752 } 4753 // The result is a pointer to the first element of the array. 4754 if (const ConstantArrayType *CAT 4755 = Info.Ctx.getAsConstantArrayType(SubExpr->getType())) 4756 Result.addArray(Info, E, CAT); 4757 else 4758 Result.Designator.setInvalid(); 4759 return true; 4760 4761 case CK_FunctionToPointerDecay: 4762 return EvaluateLValue(SubExpr, Result, Info); 4763 } 4764 4765 return ExprEvaluatorBaseTy::VisitCastExpr(E); 4766} 4767 4768bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) { 4769 if (IsStringLiteralCall(E)) 4770 return Success(E); 4771 4772 switch (E->isBuiltinCall()) { 4773 case Builtin::BI__builtin_addressof: 4774 return EvaluateLValue(E->getArg(0), Result, Info); 4775 4776 default: 4777 return ExprEvaluatorBaseTy::VisitCallExpr(E); 4778 } 4779} 4780 4781//===----------------------------------------------------------------------===// 4782// Member Pointer Evaluation 4783//===----------------------------------------------------------------------===// 4784 4785namespace { 4786class MemberPointerExprEvaluator 4787 : public ExprEvaluatorBase<MemberPointerExprEvaluator, bool> { 4788 MemberPtr &Result; 4789 4790 bool Success(const ValueDecl *D) { 4791 Result = MemberPtr(D); 4792 return true; 4793 } 4794public: 4795 4796 MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result) 4797 : ExprEvaluatorBaseTy(Info), Result(Result) {} 4798 4799 bool Success(const APValue &V, const Expr *E) { 4800 Result.setFrom(V); 4801 return true; 4802 } 4803 bool ZeroInitialization(const Expr *E) { 4804 return Success((const ValueDecl*)0); 4805 } 4806 4807 bool VisitCastExpr(const CastExpr *E); 4808 bool VisitUnaryAddrOf(const UnaryOperator *E); 4809}; 4810} // end anonymous namespace 4811 4812static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, 4813 EvalInfo &Info) { 4814 assert(E->isRValue() && E->getType()->isMemberPointerType()); 4815 return MemberPointerExprEvaluator(Info, Result).Visit(E); 4816} 4817 4818bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) { 4819 switch (E->getCastKind()) { 4820 default: 4821 return ExprEvaluatorBaseTy::VisitCastExpr(E); 4822 4823 case CK_NullToMemberPointer: 4824 VisitIgnoredValue(E->getSubExpr()); 4825 return ZeroInitialization(E); 4826 4827 case CK_BaseToDerivedMemberPointer: { 4828 if (!Visit(E->getSubExpr())) 4829 return false; 4830 if (E->path_empty()) 4831 return true; 4832 // Base-to-derived member pointer casts store the path in derived-to-base 4833 // order, so iterate backwards. The CXXBaseSpecifier also provides us with 4834 // the wrong end of the derived->base arc, so stagger the path by one class. 4835 typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter; 4836 for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin()); 4837 PathI != PathE; ++PathI) { 4838 assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); 4839 const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl(); 4840 if (!Result.castToDerived(Derived)) 4841 return Error(E); 4842 } 4843 const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass(); 4844 if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl())) 4845 return Error(E); 4846 return true; 4847 } 4848 4849 case CK_DerivedToBaseMemberPointer: 4850 if (!Visit(E->getSubExpr())) 4851 return false; 4852 for (CastExpr::path_const_iterator PathI = E->path_begin(), 4853 PathE = E->path_end(); PathI != PathE; ++PathI) { 4854 assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); 4855 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); 4856 if (!Result.castToBase(Base)) 4857 return Error(E); 4858 } 4859 return true; 4860 } 4861} 4862 4863bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { 4864 // C++11 [expr.unary.op]p3 has very strict rules on how the address of a 4865 // member can be formed. 4866 return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl()); 4867} 4868 4869//===----------------------------------------------------------------------===// 4870// Record Evaluation 4871//===----------------------------------------------------------------------===// 4872 4873namespace { 4874 class RecordExprEvaluator 4875 : public ExprEvaluatorBase<RecordExprEvaluator, bool> { 4876 const LValue &This; 4877 APValue &Result; 4878 public: 4879 4880 RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result) 4881 : ExprEvaluatorBaseTy(info), This(This), Result(Result) {} 4882 4883 bool Success(const APValue &V, const Expr *E) { 4884 Result = V; 4885 return true; 4886 } 4887 bool ZeroInitialization(const Expr *E); 4888 4889 bool VisitCastExpr(const CastExpr *E); 4890 bool VisitInitListExpr(const InitListExpr *E); 4891 bool VisitCXXConstructExpr(const CXXConstructExpr *E); 4892 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E); 4893 }; 4894} 4895 4896/// Perform zero-initialization on an object of non-union class type. 4897/// C++11 [dcl.init]p5: 4898/// To zero-initialize an object or reference of type T means: 4899/// [...] 4900/// -- if T is a (possibly cv-qualified) non-union class type, 4901/// each non-static data member and each base-class subobject is 4902/// zero-initialized 4903static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E, 4904 const RecordDecl *RD, 4905 const LValue &This, APValue &Result) { 4906 assert(!RD->isUnion() && "Expected non-union class type"); 4907 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD); 4908 Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0, 4909 std::distance(RD->field_begin(), RD->field_end())); 4910 4911 if (RD->isInvalidDecl()) return false; 4912 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 4913 4914 if (CD) { 4915 unsigned Index = 0; 4916 for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), 4917 End = CD->bases_end(); I != End; ++I, ++Index) { 4918 const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl(); 4919 LValue Subobject = This; 4920 if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout)) 4921 return false; 4922 if (!HandleClassZeroInitialization(Info, E, Base, Subobject, 4923 Result.getStructBase(Index))) 4924 return false; 4925 } 4926 } 4927 4928 for (RecordDecl::field_iterator I = RD->field_begin(), End = RD->field_end(); 4929 I != End; ++I) { 4930 // -- if T is a reference type, no initialization is performed. 4931 if (I->getType()->isReferenceType()) 4932 continue; 4933 4934 LValue Subobject = This; 4935 if (!HandleLValueMember(Info, E, Subobject, *I, &Layout)) 4936 return false; 4937 4938 ImplicitValueInitExpr VIE(I->getType()); 4939 if (!EvaluateInPlace( 4940 Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE)) 4941 return false; 4942 } 4943 4944 return true; 4945} 4946 4947bool RecordExprEvaluator::ZeroInitialization(const Expr *E) { 4948 const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl(); 4949 if (RD->isInvalidDecl()) return false; 4950 if (RD->isUnion()) { 4951 // C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the 4952 // object's first non-static named data member is zero-initialized 4953 RecordDecl::field_iterator I = RD->field_begin(); 4954 if (I == RD->field_end()) { 4955 Result = APValue((const FieldDecl*)0); 4956 return true; 4957 } 4958 4959 LValue Subobject = This; 4960 if (!HandleLValueMember(Info, E, Subobject, *I)) 4961 return false; 4962 Result = APValue(*I); 4963 ImplicitValueInitExpr VIE(I->getType()); 4964 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE); 4965 } 4966 4967 if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) { 4968 Info.Diag(E, diag::note_constexpr_virtual_base) << RD; 4969 return false; 4970 } 4971 4972 return HandleClassZeroInitialization(Info, E, RD, This, Result); 4973} 4974 4975bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) { 4976 switch (E->getCastKind()) { 4977 default: 4978 return ExprEvaluatorBaseTy::VisitCastExpr(E); 4979 4980 case CK_ConstructorConversion: 4981 return Visit(E->getSubExpr()); 4982 4983 case CK_DerivedToBase: 4984 case CK_UncheckedDerivedToBase: { 4985 APValue DerivedObject; 4986 if (!Evaluate(DerivedObject, Info, E->getSubExpr())) 4987 return false; 4988 if (!DerivedObject.isStruct()) 4989 return Error(E->getSubExpr()); 4990 4991 // Derived-to-base rvalue conversion: just slice off the derived part. 4992 APValue *Value = &DerivedObject; 4993 const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl(); 4994 for (CastExpr::path_const_iterator PathI = E->path_begin(), 4995 PathE = E->path_end(); PathI != PathE; ++PathI) { 4996 assert(!(*PathI)->isVirtual() && "record rvalue with virtual base"); 4997 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); 4998 Value = &Value->getStructBase(getBaseIndex(RD, Base)); 4999 RD = Base; 5000 } 5001 Result = *Value; 5002 return true; 5003 } 5004 } 5005} 5006 5007bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 5008 const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl(); 5009 if (RD->isInvalidDecl()) return false; 5010 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 5011 5012 if (RD->isUnion()) { 5013 const FieldDecl *Field = E->getInitializedFieldInUnion(); 5014 Result = APValue(Field); 5015 if (!Field) 5016 return true; 5017 5018 // If the initializer list for a union does not contain any elements, the 5019 // first element of the union is value-initialized. 5020 // FIXME: The element should be initialized from an initializer list. 5021 // Is this difference ever observable for initializer lists which 5022 // we don't build? 5023 ImplicitValueInitExpr VIE(Field->getType()); 5024 const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE; 5025 5026 LValue Subobject = This; 5027 if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout)) 5028 return false; 5029 5030 // Temporarily override This, in case there's a CXXDefaultInitExpr in here. 5031 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, 5032 isa<CXXDefaultInitExpr>(InitExpr)); 5033 5034 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr); 5035 } 5036 5037 assert((!isa<CXXRecordDecl>(RD) || !cast<CXXRecordDecl>(RD)->getNumBases()) && 5038 "initializer list for class with base classes"); 5039 Result = APValue(APValue::UninitStruct(), 0, 5040 std::distance(RD->field_begin(), RD->field_end())); 5041 unsigned ElementNo = 0; 5042 bool Success = true; 5043 for (RecordDecl::field_iterator Field = RD->field_begin(), 5044 FieldEnd = RD->field_end(); Field != FieldEnd; ++Field) { 5045 // Anonymous bit-fields are not considered members of the class for 5046 // purposes of aggregate initialization. 5047 if (Field->isUnnamedBitfield()) 5048 continue; 5049 5050 LValue Subobject = This; 5051 5052 bool HaveInit = ElementNo < E->getNumInits(); 5053 5054 // FIXME: Diagnostics here should point to the end of the initializer 5055 // list, not the start. 5056 if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E, 5057 Subobject, *Field, &Layout)) 5058 return false; 5059 5060 // Perform an implicit value-initialization for members beyond the end of 5061 // the initializer list. 5062 ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType()); 5063 const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE; 5064 5065 // Temporarily override This, in case there's a CXXDefaultInitExpr in here. 5066 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, 5067 isa<CXXDefaultInitExpr>(Init)); 5068 5069 APValue &FieldVal = Result.getStructField(Field->getFieldIndex()); 5070 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) || 5071 (Field->isBitField() && !truncateBitfieldValue(Info, Init, 5072 FieldVal, *Field))) { 5073 if (!Info.keepEvaluatingAfterFailure()) 5074 return false; 5075 Success = false; 5076 } 5077 } 5078 5079 return Success; 5080} 5081 5082bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { 5083 const CXXConstructorDecl *FD = E->getConstructor(); 5084 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false; 5085 5086 bool ZeroInit = E->requiresZeroInitialization(); 5087 if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { 5088 // If we've already performed zero-initialization, we're already done. 5089 if (!Result.isUninit()) 5090 return true; 5091 5092 if (ZeroInit) 5093 return ZeroInitialization(E); 5094 5095 const CXXRecordDecl *RD = FD->getParent(); 5096 if (RD->isUnion()) 5097 Result = APValue((FieldDecl*)0); 5098 else 5099 Result = APValue(APValue::UninitStruct(), RD->getNumBases(), 5100 std::distance(RD->field_begin(), RD->field_end())); 5101 return true; 5102 } 5103 5104 const FunctionDecl *Definition = 0; 5105 FD->getBody(Definition); 5106 5107 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition)) 5108 return false; 5109 5110 // Avoid materializing a temporary for an elidable copy/move constructor. 5111 if (E->isElidable() && !ZeroInit) 5112 if (const MaterializeTemporaryExpr *ME 5113 = dyn_cast<MaterializeTemporaryExpr>(E->getArg(0))) 5114 return Visit(ME->GetTemporaryExpr()); 5115 5116 if (ZeroInit && !ZeroInitialization(E)) 5117 return false; 5118 5119 ArrayRef<const Expr *> Args(E->getArgs(), E->getNumArgs()); 5120 return HandleConstructorCall(E->getExprLoc(), This, Args, 5121 cast<CXXConstructorDecl>(Definition), Info, 5122 Result); 5123} 5124 5125bool RecordExprEvaluator::VisitCXXStdInitializerListExpr( 5126 const CXXStdInitializerListExpr *E) { 5127 const ConstantArrayType *ArrayType = 5128 Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType()); 5129 5130 LValue Array; 5131 if (!EvaluateLValue(E->getSubExpr(), Array, Info)) 5132 return false; 5133 5134 // Get a pointer to the first element of the array. 5135 Array.addArray(Info, E, ArrayType); 5136 5137 // FIXME: Perform the checks on the field types in SemaInit. 5138 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl(); 5139 RecordDecl::field_iterator Field = Record->field_begin(); 5140 if (Field == Record->field_end()) 5141 return Error(E); 5142 5143 // Start pointer. 5144 if (!Field->getType()->isPointerType() || 5145 !Info.Ctx.hasSameType(Field->getType()->getPointeeType(), 5146 ArrayType->getElementType())) 5147 return Error(E); 5148 5149 // FIXME: What if the initializer_list type has base classes, etc? 5150 Result = APValue(APValue::UninitStruct(), 0, 2); 5151 Array.moveInto(Result.getStructField(0)); 5152 5153 if (++Field == Record->field_end()) 5154 return Error(E); 5155 5156 if (Field->getType()->isPointerType() && 5157 Info.Ctx.hasSameType(Field->getType()->getPointeeType(), 5158 ArrayType->getElementType())) { 5159 // End pointer. 5160 if (!HandleLValueArrayAdjustment(Info, E, Array, 5161 ArrayType->getElementType(), 5162 ArrayType->getSize().getZExtValue())) 5163 return false; 5164 Array.moveInto(Result.getStructField(1)); 5165 } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType())) 5166 // Length. 5167 Result.getStructField(1) = APValue(APSInt(ArrayType->getSize())); 5168 else 5169 return Error(E); 5170 5171 if (++Field != Record->field_end()) 5172 return Error(E); 5173 5174 return true; 5175} 5176 5177static bool EvaluateRecord(const Expr *E, const LValue &This, 5178 APValue &Result, EvalInfo &Info) { 5179 assert(E->isRValue() && E->getType()->isRecordType() && 5180 "can't evaluate expression as a record rvalue"); 5181 return RecordExprEvaluator(Info, This, Result).Visit(E); 5182} 5183 5184//===----------------------------------------------------------------------===// 5185// Temporary Evaluation 5186// 5187// Temporaries are represented in the AST as rvalues, but generally behave like 5188// lvalues. The full-object of which the temporary is a subobject is implicitly 5189// materialized so that a reference can bind to it. 5190//===----------------------------------------------------------------------===// 5191namespace { 5192class TemporaryExprEvaluator 5193 : public LValueExprEvaluatorBase<TemporaryExprEvaluator> { 5194public: 5195 TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) : 5196 LValueExprEvaluatorBaseTy(Info, Result) {} 5197 5198 /// Visit an expression which constructs the value of this temporary. 5199 bool VisitConstructExpr(const Expr *E) { 5200 Result.set(E, Info.CurrentCall->Index); 5201 return EvaluateInPlace(Info.CurrentCall->createTemporary(E, false), 5202 Info, Result, E); 5203 } 5204 5205 bool VisitCastExpr(const CastExpr *E) { 5206 switch (E->getCastKind()) { 5207 default: 5208 return LValueExprEvaluatorBaseTy::VisitCastExpr(E); 5209 5210 case CK_ConstructorConversion: 5211 return VisitConstructExpr(E->getSubExpr()); 5212 } 5213 } 5214 bool VisitInitListExpr(const InitListExpr *E) { 5215 return VisitConstructExpr(E); 5216 } 5217 bool VisitCXXConstructExpr(const CXXConstructExpr *E) { 5218 return VisitConstructExpr(E); 5219 } 5220 bool VisitCallExpr(const CallExpr *E) { 5221 return VisitConstructExpr(E); 5222 } 5223}; 5224} // end anonymous namespace 5225 5226/// Evaluate an expression of record type as a temporary. 5227static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) { 5228 assert(E->isRValue() && E->getType()->isRecordType()); 5229 return TemporaryExprEvaluator(Info, Result).Visit(E); 5230} 5231 5232//===----------------------------------------------------------------------===// 5233// Vector Evaluation 5234//===----------------------------------------------------------------------===// 5235 5236namespace { 5237 class VectorExprEvaluator 5238 : public ExprEvaluatorBase<VectorExprEvaluator, bool> { 5239 APValue &Result; 5240 public: 5241 5242 VectorExprEvaluator(EvalInfo &info, APValue &Result) 5243 : ExprEvaluatorBaseTy(info), Result(Result) {} 5244 5245 bool Success(const ArrayRef<APValue> &V, const Expr *E) { 5246 assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements()); 5247 // FIXME: remove this APValue copy. 5248 Result = APValue(V.data(), V.size()); 5249 return true; 5250 } 5251 bool Success(const APValue &V, const Expr *E) { 5252 assert(V.isVector()); 5253 Result = V; 5254 return true; 5255 } 5256 bool ZeroInitialization(const Expr *E); 5257 5258 bool VisitUnaryReal(const UnaryOperator *E) 5259 { return Visit(E->getSubExpr()); } 5260 bool VisitCastExpr(const CastExpr* E); 5261 bool VisitInitListExpr(const InitListExpr *E); 5262 bool VisitUnaryImag(const UnaryOperator *E); 5263 // FIXME: Missing: unary -, unary ~, binary add/sub/mul/div, 5264 // binary comparisons, binary and/or/xor, 5265 // shufflevector, ExtVectorElementExpr 5266 }; 5267} // end anonymous namespace 5268 5269static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) { 5270 assert(E->isRValue() && E->getType()->isVectorType() &&"not a vector rvalue"); 5271 return VectorExprEvaluator(Info, Result).Visit(E); 5272} 5273 5274bool VectorExprEvaluator::VisitCastExpr(const CastExpr* E) { 5275 const VectorType *VTy = E->getType()->castAs<VectorType>(); 5276 unsigned NElts = VTy->getNumElements(); 5277 5278 const Expr *SE = E->getSubExpr(); 5279 QualType SETy = SE->getType(); 5280 5281 switch (E->getCastKind()) { 5282 case CK_VectorSplat: { 5283 APValue Val = APValue(); 5284 if (SETy->isIntegerType()) { 5285 APSInt IntResult; 5286 if (!EvaluateInteger(SE, IntResult, Info)) 5287 return false; 5288 Val = APValue(IntResult); 5289 } else if (SETy->isRealFloatingType()) { 5290 APFloat F(0.0); 5291 if (!EvaluateFloat(SE, F, Info)) 5292 return false; 5293 Val = APValue(F); 5294 } else { 5295 return Error(E); 5296 } 5297 5298 // Splat and create vector APValue. 5299 SmallVector<APValue, 4> Elts(NElts, Val); 5300 return Success(Elts, E); 5301 } 5302 case CK_BitCast: { 5303 // Evaluate the operand into an APInt we can extract from. 5304 llvm::APInt SValInt; 5305 if (!EvalAndBitcastToAPInt(Info, SE, SValInt)) 5306 return false; 5307 // Extract the elements 5308 QualType EltTy = VTy->getElementType(); 5309 unsigned EltSize = Info.Ctx.getTypeSize(EltTy); 5310 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); 5311 SmallVector<APValue, 4> Elts; 5312 if (EltTy->isRealFloatingType()) { 5313 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy); 5314 unsigned FloatEltSize = EltSize; 5315 if (&Sem == &APFloat::x87DoubleExtended) 5316 FloatEltSize = 80; 5317 for (unsigned i = 0; i < NElts; i++) { 5318 llvm::APInt Elt; 5319 if (BigEndian) 5320 Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize); 5321 else 5322 Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize); 5323 Elts.push_back(APValue(APFloat(Sem, Elt))); 5324 } 5325 } else if (EltTy->isIntegerType()) { 5326 for (unsigned i = 0; i < NElts; i++) { 5327 llvm::APInt Elt; 5328 if (BigEndian) 5329 Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize); 5330 else 5331 Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize); 5332 Elts.push_back(APValue(APSInt(Elt, EltTy->isSignedIntegerType()))); 5333 } 5334 } else { 5335 return Error(E); 5336 } 5337 return Success(Elts, E); 5338 } 5339 default: 5340 return ExprEvaluatorBaseTy::VisitCastExpr(E); 5341 } 5342} 5343 5344bool 5345VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 5346 const VectorType *VT = E->getType()->castAs<VectorType>(); 5347 unsigned NumInits = E->getNumInits(); 5348 unsigned NumElements = VT->getNumElements(); 5349 5350 QualType EltTy = VT->getElementType(); 5351 SmallVector<APValue, 4> Elements; 5352 5353 // The number of initializers can be less than the number of 5354 // vector elements. For OpenCL, this can be due to nested vector 5355 // initialization. For GCC compatibility, missing trailing elements 5356 // should be initialized with zeroes. 5357 unsigned CountInits = 0, CountElts = 0; 5358 while (CountElts < NumElements) { 5359 // Handle nested vector initialization. 5360 if (CountInits < NumInits 5361 && E->getInit(CountInits)->getType()->isVectorType()) { 5362 APValue v; 5363 if (!EvaluateVector(E->getInit(CountInits), v, Info)) 5364 return Error(E); 5365 unsigned vlen = v.getVectorLength(); 5366 for (unsigned j = 0; j < vlen; j++) 5367 Elements.push_back(v.getVectorElt(j)); 5368 CountElts += vlen; 5369 } else if (EltTy->isIntegerType()) { 5370 llvm::APSInt sInt(32); 5371 if (CountInits < NumInits) { 5372 if (!EvaluateInteger(E->getInit(CountInits), sInt, Info)) 5373 return false; 5374 } else // trailing integer zero. 5375 sInt = Info.Ctx.MakeIntValue(0, EltTy); 5376 Elements.push_back(APValue(sInt)); 5377 CountElts++; 5378 } else { 5379 llvm::APFloat f(0.0); 5380 if (CountInits < NumInits) { 5381 if (!EvaluateFloat(E->getInit(CountInits), f, Info)) 5382 return false; 5383 } else // trailing float zero. 5384 f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)); 5385 Elements.push_back(APValue(f)); 5386 CountElts++; 5387 } 5388 CountInits++; 5389 } 5390 return Success(Elements, E); 5391} 5392 5393bool 5394VectorExprEvaluator::ZeroInitialization(const Expr *E) { 5395 const VectorType *VT = E->getType()->getAs<VectorType>(); 5396 QualType EltTy = VT->getElementType(); 5397 APValue ZeroElement; 5398 if (EltTy->isIntegerType()) 5399 ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy)); 5400 else 5401 ZeroElement = 5402 APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy))); 5403 5404 SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement); 5405 return Success(Elements, E); 5406} 5407 5408bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 5409 VisitIgnoredValue(E->getSubExpr()); 5410 return ZeroInitialization(E); 5411} 5412 5413//===----------------------------------------------------------------------===// 5414// Array Evaluation 5415//===----------------------------------------------------------------------===// 5416 5417namespace { 5418 class ArrayExprEvaluator 5419 : public ExprEvaluatorBase<ArrayExprEvaluator, bool> { 5420 const LValue &This; 5421 APValue &Result; 5422 public: 5423 5424 ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result) 5425 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {} 5426 5427 bool Success(const APValue &V, const Expr *E) { 5428 assert((V.isArray() || V.isLValue()) && 5429 "expected array or string literal"); 5430 Result = V; 5431 return true; 5432 } 5433 5434 bool ZeroInitialization(const Expr *E) { 5435 const ConstantArrayType *CAT = 5436 Info.Ctx.getAsConstantArrayType(E->getType()); 5437 if (!CAT) 5438 return Error(E); 5439 5440 Result = APValue(APValue::UninitArray(), 0, 5441 CAT->getSize().getZExtValue()); 5442 if (!Result.hasArrayFiller()) return true; 5443 5444 // Zero-initialize all elements. 5445 LValue Subobject = This; 5446 Subobject.addArray(Info, E, CAT); 5447 ImplicitValueInitExpr VIE(CAT->getElementType()); 5448 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE); 5449 } 5450 5451 bool VisitInitListExpr(const InitListExpr *E); 5452 bool VisitCXXConstructExpr(const CXXConstructExpr *E); 5453 bool VisitCXXConstructExpr(const CXXConstructExpr *E, 5454 const LValue &Subobject, 5455 APValue *Value, QualType Type); 5456 }; 5457} // end anonymous namespace 5458 5459static bool EvaluateArray(const Expr *E, const LValue &This, 5460 APValue &Result, EvalInfo &Info) { 5461 assert(E->isRValue() && E->getType()->isArrayType() && "not an array rvalue"); 5462 return ArrayExprEvaluator(Info, This, Result).Visit(E); 5463} 5464 5465bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 5466 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(E->getType()); 5467 if (!CAT) 5468 return Error(E); 5469 5470 // C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...] 5471 // an appropriately-typed string literal enclosed in braces. 5472 if (E->isStringLiteralInit()) { 5473 LValue LV; 5474 if (!EvaluateLValue(E->getInit(0), LV, Info)) 5475 return false; 5476 APValue Val; 5477 LV.moveInto(Val); 5478 return Success(Val, E); 5479 } 5480 5481 bool Success = true; 5482 5483 assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) && 5484 "zero-initialized array shouldn't have any initialized elts"); 5485 APValue Filler; 5486 if (Result.isArray() && Result.hasArrayFiller()) 5487 Filler = Result.getArrayFiller(); 5488 5489 unsigned NumEltsToInit = E->getNumInits(); 5490 unsigned NumElts = CAT->getSize().getZExtValue(); 5491 const Expr *FillerExpr = E->hasArrayFiller() ? E->getArrayFiller() : 0; 5492 5493 // If the initializer might depend on the array index, run it for each 5494 // array element. For now, just whitelist non-class value-initialization. 5495 if (NumEltsToInit != NumElts && !isa<ImplicitValueInitExpr>(FillerExpr)) 5496 NumEltsToInit = NumElts; 5497 5498 Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts); 5499 5500 // If the array was previously zero-initialized, preserve the 5501 // zero-initialized values. 5502 if (!Filler.isUninit()) { 5503 for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I) 5504 Result.getArrayInitializedElt(I) = Filler; 5505 if (Result.hasArrayFiller()) 5506 Result.getArrayFiller() = Filler; 5507 } 5508 5509 LValue Subobject = This; 5510 Subobject.addArray(Info, E, CAT); 5511 for (unsigned Index = 0; Index != NumEltsToInit; ++Index) { 5512 const Expr *Init = 5513 Index < E->getNumInits() ? E->getInit(Index) : FillerExpr; 5514 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), 5515 Info, Subobject, Init) || 5516 !HandleLValueArrayAdjustment(Info, Init, Subobject, 5517 CAT->getElementType(), 1)) { 5518 if (!Info.keepEvaluatingAfterFailure()) 5519 return false; 5520 Success = false; 5521 } 5522 } 5523 5524 if (!Result.hasArrayFiller()) 5525 return Success; 5526 5527 // If we get here, we have a trivial filler, which we can just evaluate 5528 // once and splat over the rest of the array elements. 5529 assert(FillerExpr && "no array filler for incomplete init list"); 5530 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, 5531 FillerExpr) && Success; 5532} 5533 5534bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { 5535 return VisitCXXConstructExpr(E, This, &Result, E->getType()); 5536} 5537 5538bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E, 5539 const LValue &Subobject, 5540 APValue *Value, 5541 QualType Type) { 5542 bool HadZeroInit = !Value->isUninit(); 5543 5544 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) { 5545 unsigned N = CAT->getSize().getZExtValue(); 5546 5547 // Preserve the array filler if we had prior zero-initialization. 5548 APValue Filler = 5549 HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller() 5550 : APValue(); 5551 5552 *Value = APValue(APValue::UninitArray(), N, N); 5553 5554 if (HadZeroInit) 5555 for (unsigned I = 0; I != N; ++I) 5556 Value->getArrayInitializedElt(I) = Filler; 5557 5558 // Initialize the elements. 5559 LValue ArrayElt = Subobject; 5560 ArrayElt.addArray(Info, E, CAT); 5561 for (unsigned I = 0; I != N; ++I) 5562 if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I), 5563 CAT->getElementType()) || 5564 !HandleLValueArrayAdjustment(Info, E, ArrayElt, 5565 CAT->getElementType(), 1)) 5566 return false; 5567 5568 return true; 5569 } 5570 5571 if (!Type->isRecordType()) 5572 return Error(E); 5573 5574 const CXXConstructorDecl *FD = E->getConstructor(); 5575 5576 bool ZeroInit = E->requiresZeroInitialization(); 5577 if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { 5578 if (HadZeroInit) 5579 return true; 5580 5581 if (ZeroInit) { 5582 ImplicitValueInitExpr VIE(Type); 5583 return EvaluateInPlace(*Value, Info, Subobject, &VIE); 5584 } 5585 5586 const CXXRecordDecl *RD = FD->getParent(); 5587 if (RD->isUnion()) 5588 *Value = APValue((FieldDecl*)0); 5589 else 5590 *Value = 5591 APValue(APValue::UninitStruct(), RD->getNumBases(), 5592 std::distance(RD->field_begin(), RD->field_end())); 5593 return true; 5594 } 5595 5596 const FunctionDecl *Definition = 0; 5597 FD->getBody(Definition); 5598 5599 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition)) 5600 return false; 5601 5602 if (ZeroInit && !HadZeroInit) { 5603 ImplicitValueInitExpr VIE(Type); 5604 if (!EvaluateInPlace(*Value, Info, Subobject, &VIE)) 5605 return false; 5606 } 5607 5608 ArrayRef<const Expr *> Args(E->getArgs(), E->getNumArgs()); 5609 return HandleConstructorCall(E->getExprLoc(), Subobject, Args, 5610 cast<CXXConstructorDecl>(Definition), 5611 Info, *Value); 5612} 5613 5614//===----------------------------------------------------------------------===// 5615// Integer Evaluation 5616// 5617// As a GNU extension, we support casting pointers to sufficiently-wide integer 5618// types and back in constant folding. Integer values are thus represented 5619// either as an integer-valued APValue, or as an lvalue-valued APValue. 5620//===----------------------------------------------------------------------===// 5621 5622namespace { 5623class IntExprEvaluator 5624 : public ExprEvaluatorBase<IntExprEvaluator, bool> { 5625 APValue &Result; 5626public: 5627 IntExprEvaluator(EvalInfo &info, APValue &result) 5628 : ExprEvaluatorBaseTy(info), Result(result) {} 5629 5630 bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) { 5631 assert(E->getType()->isIntegralOrEnumerationType() && 5632 "Invalid evaluation result."); 5633 assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() && 5634 "Invalid evaluation result."); 5635 assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && 5636 "Invalid evaluation result."); 5637 Result = APValue(SI); 5638 return true; 5639 } 5640 bool Success(const llvm::APSInt &SI, const Expr *E) { 5641 return Success(SI, E, Result); 5642 } 5643 5644 bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) { 5645 assert(E->getType()->isIntegralOrEnumerationType() && 5646 "Invalid evaluation result."); 5647 assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && 5648 "Invalid evaluation result."); 5649 Result = APValue(APSInt(I)); 5650 Result.getInt().setIsUnsigned( 5651 E->getType()->isUnsignedIntegerOrEnumerationType()); 5652 return true; 5653 } 5654 bool Success(const llvm::APInt &I, const Expr *E) { 5655 return Success(I, E, Result); 5656 } 5657 5658 bool Success(uint64_t Value, const Expr *E, APValue &Result) { 5659 assert(E->getType()->isIntegralOrEnumerationType() && 5660 "Invalid evaluation result."); 5661 Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType())); 5662 return true; 5663 } 5664 bool Success(uint64_t Value, const Expr *E) { 5665 return Success(Value, E, Result); 5666 } 5667 5668 bool Success(CharUnits Size, const Expr *E) { 5669 return Success(Size.getQuantity(), E); 5670 } 5671 5672 bool Success(const APValue &V, const Expr *E) { 5673 if (V.isLValue() || V.isAddrLabelDiff()) { 5674 Result = V; 5675 return true; 5676 } 5677 return Success(V.getInt(), E); 5678 } 5679 5680 bool ZeroInitialization(const Expr *E) { return Success(0, E); } 5681 5682 //===--------------------------------------------------------------------===// 5683 // Visitor Methods 5684 //===--------------------------------------------------------------------===// 5685 5686 bool VisitIntegerLiteral(const IntegerLiteral *E) { 5687 return Success(E->getValue(), E); 5688 } 5689 bool VisitCharacterLiteral(const CharacterLiteral *E) { 5690 return Success(E->getValue(), E); 5691 } 5692 5693 bool CheckReferencedDecl(const Expr *E, const Decl *D); 5694 bool VisitDeclRefExpr(const DeclRefExpr *E) { 5695 if (CheckReferencedDecl(E, E->getDecl())) 5696 return true; 5697 5698 return ExprEvaluatorBaseTy::VisitDeclRefExpr(E); 5699 } 5700 bool VisitMemberExpr(const MemberExpr *E) { 5701 if (CheckReferencedDecl(E, E->getMemberDecl())) { 5702 VisitIgnoredValue(E->getBase()); 5703 return true; 5704 } 5705 5706 return ExprEvaluatorBaseTy::VisitMemberExpr(E); 5707 } 5708 5709 bool VisitCallExpr(const CallExpr *E); 5710 bool VisitBinaryOperator(const BinaryOperator *E); 5711 bool VisitOffsetOfExpr(const OffsetOfExpr *E); 5712 bool VisitUnaryOperator(const UnaryOperator *E); 5713 5714 bool VisitCastExpr(const CastExpr* E); 5715 bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E); 5716 5717 bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) { 5718 return Success(E->getValue(), E); 5719 } 5720 5721 bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) { 5722 return Success(E->getValue(), E); 5723 } 5724 5725 // Note, GNU defines __null as an integer, not a pointer. 5726 bool VisitGNUNullExpr(const GNUNullExpr *E) { 5727 return ZeroInitialization(E); 5728 } 5729 5730 bool VisitUnaryTypeTraitExpr(const UnaryTypeTraitExpr *E) { 5731 return Success(E->getValue(), E); 5732 } 5733 5734 bool VisitBinaryTypeTraitExpr(const BinaryTypeTraitExpr *E) { 5735 return Success(E->getValue(), E); 5736 } 5737 5738 bool VisitTypeTraitExpr(const TypeTraitExpr *E) { 5739 return Success(E->getValue(), E); 5740 } 5741 5742 bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) { 5743 return Success(E->getValue(), E); 5744 } 5745 5746 bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) { 5747 return Success(E->getValue(), E); 5748 } 5749 5750 bool VisitUnaryReal(const UnaryOperator *E); 5751 bool VisitUnaryImag(const UnaryOperator *E); 5752 5753 bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E); 5754 bool VisitSizeOfPackExpr(const SizeOfPackExpr *E); 5755 5756private: 5757 CharUnits GetAlignOfExpr(const Expr *E); 5758 CharUnits GetAlignOfType(QualType T); 5759 static QualType GetObjectType(APValue::LValueBase B); 5760 bool TryEvaluateBuiltinObjectSize(const CallExpr *E); 5761 // FIXME: Missing: array subscript of vector, member of vector 5762}; 5763} // end anonymous namespace 5764 5765/// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and 5766/// produce either the integer value or a pointer. 5767/// 5768/// GCC has a heinous extension which folds casts between pointer types and 5769/// pointer-sized integral types. We support this by allowing the evaluation of 5770/// an integer rvalue to produce a pointer (represented as an lvalue) instead. 5771/// Some simple arithmetic on such values is supported (they are treated much 5772/// like char*). 5773static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, 5774 EvalInfo &Info) { 5775 assert(E->isRValue() && E->getType()->isIntegralOrEnumerationType()); 5776 return IntExprEvaluator(Info, Result).Visit(E); 5777} 5778 5779static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) { 5780 APValue Val; 5781 if (!EvaluateIntegerOrLValue(E, Val, Info)) 5782 return false; 5783 if (!Val.isInt()) { 5784 // FIXME: It would be better to produce the diagnostic for casting 5785 // a pointer to an integer. 5786 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 5787 return false; 5788 } 5789 Result = Val.getInt(); 5790 return true; 5791} 5792 5793/// Check whether the given declaration can be directly converted to an integral 5794/// rvalue. If not, no diagnostic is produced; there are other things we can 5795/// try. 5796bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) { 5797 // Enums are integer constant exprs. 5798 if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) { 5799 // Check for signedness/width mismatches between E type and ECD value. 5800 bool SameSign = (ECD->getInitVal().isSigned() 5801 == E->getType()->isSignedIntegerOrEnumerationType()); 5802 bool SameWidth = (ECD->getInitVal().getBitWidth() 5803 == Info.Ctx.getIntWidth(E->getType())); 5804 if (SameSign && SameWidth) 5805 return Success(ECD->getInitVal(), E); 5806 else { 5807 // Get rid of mismatch (otherwise Success assertions will fail) 5808 // by computing a new value matching the type of E. 5809 llvm::APSInt Val = ECD->getInitVal(); 5810 if (!SameSign) 5811 Val.setIsSigned(!ECD->getInitVal().isSigned()); 5812 if (!SameWidth) 5813 Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType())); 5814 return Success(Val, E); 5815 } 5816 } 5817 return false; 5818} 5819 5820/// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way 5821/// as GCC. 5822static int EvaluateBuiltinClassifyType(const CallExpr *E) { 5823 // The following enum mimics the values returned by GCC. 5824 // FIXME: Does GCC differ between lvalue and rvalue references here? 5825 enum gcc_type_class { 5826 no_type_class = -1, 5827 void_type_class, integer_type_class, char_type_class, 5828 enumeral_type_class, boolean_type_class, 5829 pointer_type_class, reference_type_class, offset_type_class, 5830 real_type_class, complex_type_class, 5831 function_type_class, method_type_class, 5832 record_type_class, union_type_class, 5833 array_type_class, string_type_class, 5834 lang_type_class 5835 }; 5836 5837 // If no argument was supplied, default to "no_type_class". This isn't 5838 // ideal, however it is what gcc does. 5839 if (E->getNumArgs() == 0) 5840 return no_type_class; 5841 5842 QualType ArgTy = E->getArg(0)->getType(); 5843 if (ArgTy->isVoidType()) 5844 return void_type_class; 5845 else if (ArgTy->isEnumeralType()) 5846 return enumeral_type_class; 5847 else if (ArgTy->isBooleanType()) 5848 return boolean_type_class; 5849 else if (ArgTy->isCharType()) 5850 return string_type_class; // gcc doesn't appear to use char_type_class 5851 else if (ArgTy->isIntegerType()) 5852 return integer_type_class; 5853 else if (ArgTy->isPointerType()) 5854 return pointer_type_class; 5855 else if (ArgTy->isReferenceType()) 5856 return reference_type_class; 5857 else if (ArgTy->isRealType()) 5858 return real_type_class; 5859 else if (ArgTy->isComplexType()) 5860 return complex_type_class; 5861 else if (ArgTy->isFunctionType()) 5862 return function_type_class; 5863 else if (ArgTy->isStructureOrClassType()) 5864 return record_type_class; 5865 else if (ArgTy->isUnionType()) 5866 return union_type_class; 5867 else if (ArgTy->isArrayType()) 5868 return array_type_class; 5869 else if (ArgTy->isUnionType()) 5870 return union_type_class; 5871 else // FIXME: offset_type_class, method_type_class, & lang_type_class? 5872 llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type"); 5873} 5874 5875/// EvaluateBuiltinConstantPForLValue - Determine the result of 5876/// __builtin_constant_p when applied to the given lvalue. 5877/// 5878/// An lvalue is only "constant" if it is a pointer or reference to the first 5879/// character of a string literal. 5880template<typename LValue> 5881static bool EvaluateBuiltinConstantPForLValue(const LValue &LV) { 5882 const Expr *E = LV.getLValueBase().template dyn_cast<const Expr*>(); 5883 return E && isa<StringLiteral>(E) && LV.getLValueOffset().isZero(); 5884} 5885 5886/// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to 5887/// GCC as we can manage. 5888static bool EvaluateBuiltinConstantP(ASTContext &Ctx, const Expr *Arg) { 5889 QualType ArgType = Arg->getType(); 5890 5891 // __builtin_constant_p always has one operand. The rules which gcc follows 5892 // are not precisely documented, but are as follows: 5893 // 5894 // - If the operand is of integral, floating, complex or enumeration type, 5895 // and can be folded to a known value of that type, it returns 1. 5896 // - If the operand and can be folded to a pointer to the first character 5897 // of a string literal (or such a pointer cast to an integral type), it 5898 // returns 1. 5899 // 5900 // Otherwise, it returns 0. 5901 // 5902 // FIXME: GCC also intends to return 1 for literals of aggregate types, but 5903 // its support for this does not currently work. 5904 if (ArgType->isIntegralOrEnumerationType()) { 5905 Expr::EvalResult Result; 5906 if (!Arg->EvaluateAsRValue(Result, Ctx) || Result.HasSideEffects) 5907 return false; 5908 5909 APValue &V = Result.Val; 5910 if (V.getKind() == APValue::Int) 5911 return true; 5912 5913 return EvaluateBuiltinConstantPForLValue(V); 5914 } else if (ArgType->isFloatingType() || ArgType->isAnyComplexType()) { 5915 return Arg->isEvaluatable(Ctx); 5916 } else if (ArgType->isPointerType() || Arg->isGLValue()) { 5917 LValue LV; 5918 Expr::EvalStatus Status; 5919 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold); 5920 if ((Arg->isGLValue() ? EvaluateLValue(Arg, LV, Info) 5921 : EvaluatePointer(Arg, LV, Info)) && 5922 !Status.HasSideEffects) 5923 return EvaluateBuiltinConstantPForLValue(LV); 5924 } 5925 5926 // Anything else isn't considered to be sufficiently constant. 5927 return false; 5928} 5929 5930/// Retrieves the "underlying object type" of the given expression, 5931/// as used by __builtin_object_size. 5932QualType IntExprEvaluator::GetObjectType(APValue::LValueBase B) { 5933 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { 5934 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 5935 return VD->getType(); 5936 } else if (const Expr *E = B.get<const Expr*>()) { 5937 if (isa<CompoundLiteralExpr>(E)) 5938 return E->getType(); 5939 } 5940 5941 return QualType(); 5942} 5943 5944bool IntExprEvaluator::TryEvaluateBuiltinObjectSize(const CallExpr *E) { 5945 LValue Base; 5946 5947 { 5948 // The operand of __builtin_object_size is never evaluated for side-effects. 5949 // If there are any, but we can determine the pointed-to object anyway, then 5950 // ignore the side-effects. 5951 SpeculativeEvaluationRAII SpeculativeEval(Info); 5952 if (!EvaluatePointer(E->getArg(0), Base, Info)) 5953 return false; 5954 } 5955 5956 // If we can prove the base is null, lower to zero now. 5957 if (!Base.getLValueBase()) return Success(0, E); 5958 5959 QualType T = GetObjectType(Base.getLValueBase()); 5960 if (T.isNull() || 5961 T->isIncompleteType() || 5962 T->isFunctionType() || 5963 T->isVariablyModifiedType() || 5964 T->isDependentType()) 5965 return Error(E); 5966 5967 CharUnits Size = Info.Ctx.getTypeSizeInChars(T); 5968 CharUnits Offset = Base.getLValueOffset(); 5969 5970 if (!Offset.isNegative() && Offset <= Size) 5971 Size -= Offset; 5972 else 5973 Size = CharUnits::Zero(); 5974 return Success(Size, E); 5975} 5976 5977bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) { 5978 switch (unsigned BuiltinOp = E->isBuiltinCall()) { 5979 default: 5980 return ExprEvaluatorBaseTy::VisitCallExpr(E); 5981 5982 case Builtin::BI__builtin_object_size: { 5983 if (TryEvaluateBuiltinObjectSize(E)) 5984 return true; 5985 5986 // If evaluating the argument has side-effects, we can't determine the size 5987 // of the object, and so we lower it to unknown now. CodeGen relies on us to 5988 // handle all cases where the expression has side-effects. 5989 if (E->getArg(0)->HasSideEffects(Info.Ctx)) { 5990 if (E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue() <= 1) 5991 return Success(-1ULL, E); 5992 return Success(0, E); 5993 } 5994 5995 // Expression had no side effects, but we couldn't statically determine the 5996 // size of the referenced object. 5997 return Error(E); 5998 } 5999 6000 case Builtin::BI__builtin_bswap16: 6001 case Builtin::BI__builtin_bswap32: 6002 case Builtin::BI__builtin_bswap64: { 6003 APSInt Val; 6004 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6005 return false; 6006 6007 return Success(Val.byteSwap(), E); 6008 } 6009 6010 case Builtin::BI__builtin_classify_type: 6011 return Success(EvaluateBuiltinClassifyType(E), E); 6012 6013 // FIXME: BI__builtin_clrsb 6014 // FIXME: BI__builtin_clrsbl 6015 // FIXME: BI__builtin_clrsbll 6016 6017 case Builtin::BI__builtin_clz: 6018 case Builtin::BI__builtin_clzl: 6019 case Builtin::BI__builtin_clzll: { 6020 APSInt Val; 6021 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6022 return false; 6023 if (!Val) 6024 return Error(E); 6025 6026 return Success(Val.countLeadingZeros(), E); 6027 } 6028 6029 case Builtin::BI__builtin_constant_p: 6030 return Success(EvaluateBuiltinConstantP(Info.Ctx, E->getArg(0)), E); 6031 6032 case Builtin::BI__builtin_ctz: 6033 case Builtin::BI__builtin_ctzl: 6034 case Builtin::BI__builtin_ctzll: { 6035 APSInt Val; 6036 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6037 return false; 6038 if (!Val) 6039 return Error(E); 6040 6041 return Success(Val.countTrailingZeros(), E); 6042 } 6043 6044 case Builtin::BI__builtin_eh_return_data_regno: { 6045 int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); 6046 Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand); 6047 return Success(Operand, E); 6048 } 6049 6050 case Builtin::BI__builtin_expect: 6051 return Visit(E->getArg(0)); 6052 6053 case Builtin::BI__builtin_ffs: 6054 case Builtin::BI__builtin_ffsl: 6055 case Builtin::BI__builtin_ffsll: { 6056 APSInt Val; 6057 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6058 return false; 6059 6060 unsigned N = Val.countTrailingZeros(); 6061 return Success(N == Val.getBitWidth() ? 0 : N + 1, E); 6062 } 6063 6064 case Builtin::BI__builtin_fpclassify: { 6065 APFloat Val(0.0); 6066 if (!EvaluateFloat(E->getArg(5), Val, Info)) 6067 return false; 6068 unsigned Arg; 6069 switch (Val.getCategory()) { 6070 case APFloat::fcNaN: Arg = 0; break; 6071 case APFloat::fcInfinity: Arg = 1; break; 6072 case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break; 6073 case APFloat::fcZero: Arg = 4; break; 6074 } 6075 return Visit(E->getArg(Arg)); 6076 } 6077 6078 case Builtin::BI__builtin_isinf_sign: { 6079 APFloat Val(0.0); 6080 return EvaluateFloat(E->getArg(0), Val, Info) && 6081 Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E); 6082 } 6083 6084 case Builtin::BI__builtin_isinf: { 6085 APFloat Val(0.0); 6086 return EvaluateFloat(E->getArg(0), Val, Info) && 6087 Success(Val.isInfinity() ? 1 : 0, E); 6088 } 6089 6090 case Builtin::BI__builtin_isfinite: { 6091 APFloat Val(0.0); 6092 return EvaluateFloat(E->getArg(0), Val, Info) && 6093 Success(Val.isFinite() ? 1 : 0, E); 6094 } 6095 6096 case Builtin::BI__builtin_isnan: { 6097 APFloat Val(0.0); 6098 return EvaluateFloat(E->getArg(0), Val, Info) && 6099 Success(Val.isNaN() ? 1 : 0, E); 6100 } 6101 6102 case Builtin::BI__builtin_isnormal: { 6103 APFloat Val(0.0); 6104 return EvaluateFloat(E->getArg(0), Val, Info) && 6105 Success(Val.isNormal() ? 1 : 0, E); 6106 } 6107 6108 case Builtin::BI__builtin_parity: 6109 case Builtin::BI__builtin_parityl: 6110 case Builtin::BI__builtin_parityll: { 6111 APSInt Val; 6112 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6113 return false; 6114 6115 return Success(Val.countPopulation() % 2, E); 6116 } 6117 6118 case Builtin::BI__builtin_popcount: 6119 case Builtin::BI__builtin_popcountl: 6120 case Builtin::BI__builtin_popcountll: { 6121 APSInt Val; 6122 if (!EvaluateInteger(E->getArg(0), Val, Info)) 6123 return false; 6124 6125 return Success(Val.countPopulation(), E); 6126 } 6127 6128 case Builtin::BIstrlen: 6129 // A call to strlen is not a constant expression. 6130 if (Info.getLangOpts().CPlusPlus11) 6131 Info.CCEDiag(E, diag::note_constexpr_invalid_function) 6132 << /*isConstexpr*/0 << /*isConstructor*/0 << "'strlen'"; 6133 else 6134 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 6135 // Fall through. 6136 case Builtin::BI__builtin_strlen: { 6137 // As an extension, we support __builtin_strlen() as a constant expression, 6138 // and support folding strlen() to a constant. 6139 LValue String; 6140 if (!EvaluatePointer(E->getArg(0), String, Info)) 6141 return false; 6142 6143 // Fast path: if it's a string literal, search the string value. 6144 if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>( 6145 String.getLValueBase().dyn_cast<const Expr *>())) { 6146 // The string literal may have embedded null characters. Find the first 6147 // one and truncate there. 6148 StringRef Str = S->getBytes(); 6149 int64_t Off = String.Offset.getQuantity(); 6150 if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() && 6151 S->getCharByteWidth() == 1) { 6152 Str = Str.substr(Off); 6153 6154 StringRef::size_type Pos = Str.find(0); 6155 if (Pos != StringRef::npos) 6156 Str = Str.substr(0, Pos); 6157 6158 return Success(Str.size(), E); 6159 } 6160 6161 // Fall through to slow path to issue appropriate diagnostic. 6162 } 6163 6164 // Slow path: scan the bytes of the string looking for the terminating 0. 6165 QualType CharTy = E->getArg(0)->getType()->getPointeeType(); 6166 for (uint64_t Strlen = 0; /**/; ++Strlen) { 6167 APValue Char; 6168 if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) || 6169 !Char.isInt()) 6170 return false; 6171 if (!Char.getInt()) 6172 return Success(Strlen, E); 6173 if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1)) 6174 return false; 6175 } 6176 } 6177 6178 case Builtin::BI__atomic_always_lock_free: 6179 case Builtin::BI__atomic_is_lock_free: 6180 case Builtin::BI__c11_atomic_is_lock_free: { 6181 APSInt SizeVal; 6182 if (!EvaluateInteger(E->getArg(0), SizeVal, Info)) 6183 return false; 6184 6185 // For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power 6186 // of two less than the maximum inline atomic width, we know it is 6187 // lock-free. If the size isn't a power of two, or greater than the 6188 // maximum alignment where we promote atomics, we know it is not lock-free 6189 // (at least not in the sense of atomic_is_lock_free). Otherwise, 6190 // the answer can only be determined at runtime; for example, 16-byte 6191 // atomics have lock-free implementations on some, but not all, 6192 // x86-64 processors. 6193 6194 // Check power-of-two. 6195 CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue()); 6196 if (Size.isPowerOfTwo()) { 6197 // Check against inlining width. 6198 unsigned InlineWidthBits = 6199 Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth(); 6200 if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) { 6201 if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free || 6202 Size == CharUnits::One() || 6203 E->getArg(1)->isNullPointerConstant(Info.Ctx, 6204 Expr::NPC_NeverValueDependent)) 6205 // OK, we will inline appropriately-aligned operations of this size, 6206 // and _Atomic(T) is appropriately-aligned. 6207 return Success(1, E); 6208 6209 QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()-> 6210 castAs<PointerType>()->getPointeeType(); 6211 if (!PointeeType->isIncompleteType() && 6212 Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) { 6213 // OK, we will inline operations on this object. 6214 return Success(1, E); 6215 } 6216 } 6217 } 6218 6219 return BuiltinOp == Builtin::BI__atomic_always_lock_free ? 6220 Success(0, E) : Error(E); 6221 } 6222 } 6223} 6224 6225static bool HasSameBase(const LValue &A, const LValue &B) { 6226 if (!A.getLValueBase()) 6227 return !B.getLValueBase(); 6228 if (!B.getLValueBase()) 6229 return false; 6230 6231 if (A.getLValueBase().getOpaqueValue() != 6232 B.getLValueBase().getOpaqueValue()) { 6233 const Decl *ADecl = GetLValueBaseDecl(A); 6234 if (!ADecl) 6235 return false; 6236 const Decl *BDecl = GetLValueBaseDecl(B); 6237 if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl()) 6238 return false; 6239 } 6240 6241 return IsGlobalLValue(A.getLValueBase()) || 6242 A.getLValueCallIndex() == B.getLValueCallIndex(); 6243} 6244 6245namespace { 6246 6247/// \brief Data recursive integer evaluator of certain binary operators. 6248/// 6249/// We use a data recursive algorithm for binary operators so that we are able 6250/// to handle extreme cases of chained binary operators without causing stack 6251/// overflow. 6252class DataRecursiveIntBinOpEvaluator { 6253 struct EvalResult { 6254 APValue Val; 6255 bool Failed; 6256 6257 EvalResult() : Failed(false) { } 6258 6259 void swap(EvalResult &RHS) { 6260 Val.swap(RHS.Val); 6261 Failed = RHS.Failed; 6262 RHS.Failed = false; 6263 } 6264 }; 6265 6266 struct Job { 6267 const Expr *E; 6268 EvalResult LHSResult; // meaningful only for binary operator expression. 6269 enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind; 6270 6271 Job() : StoredInfo(0) { } 6272 void startSpeculativeEval(EvalInfo &Info) { 6273 OldEvalStatus = Info.EvalStatus; 6274 Info.EvalStatus.Diag = 0; 6275 StoredInfo = &Info; 6276 } 6277 ~Job() { 6278 if (StoredInfo) { 6279 StoredInfo->EvalStatus = OldEvalStatus; 6280 } 6281 } 6282 private: 6283 EvalInfo *StoredInfo; // non-null if status changed. 6284 Expr::EvalStatus OldEvalStatus; 6285 }; 6286 6287 SmallVector<Job, 16> Queue; 6288 6289 IntExprEvaluator &IntEval; 6290 EvalInfo &Info; 6291 APValue &FinalResult; 6292 6293public: 6294 DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result) 6295 : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { } 6296 6297 /// \brief True if \param E is a binary operator that we are going to handle 6298 /// data recursively. 6299 /// We handle binary operators that are comma, logical, or that have operands 6300 /// with integral or enumeration type. 6301 static bool shouldEnqueue(const BinaryOperator *E) { 6302 return E->getOpcode() == BO_Comma || 6303 E->isLogicalOp() || 6304 (E->getLHS()->getType()->isIntegralOrEnumerationType() && 6305 E->getRHS()->getType()->isIntegralOrEnumerationType()); 6306 } 6307 6308 bool Traverse(const BinaryOperator *E) { 6309 enqueue(E); 6310 EvalResult PrevResult; 6311 while (!Queue.empty()) 6312 process(PrevResult); 6313 6314 if (PrevResult.Failed) return false; 6315 6316 FinalResult.swap(PrevResult.Val); 6317 return true; 6318 } 6319 6320private: 6321 bool Success(uint64_t Value, const Expr *E, APValue &Result) { 6322 return IntEval.Success(Value, E, Result); 6323 } 6324 bool Success(const APSInt &Value, const Expr *E, APValue &Result) { 6325 return IntEval.Success(Value, E, Result); 6326 } 6327 bool Error(const Expr *E) { 6328 return IntEval.Error(E); 6329 } 6330 bool Error(const Expr *E, diag::kind D) { 6331 return IntEval.Error(E, D); 6332 } 6333 6334 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { 6335 return Info.CCEDiag(E, D); 6336 } 6337 6338 // \brief Returns true if visiting the RHS is necessary, false otherwise. 6339 bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, 6340 bool &SuppressRHSDiags); 6341 6342 bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, 6343 const BinaryOperator *E, APValue &Result); 6344 6345 void EvaluateExpr(const Expr *E, EvalResult &Result) { 6346 Result.Failed = !Evaluate(Result.Val, Info, E); 6347 if (Result.Failed) 6348 Result.Val = APValue(); 6349 } 6350 6351 void process(EvalResult &Result); 6352 6353 void enqueue(const Expr *E) { 6354 E = E->IgnoreParens(); 6355 Queue.resize(Queue.size()+1); 6356 Queue.back().E = E; 6357 Queue.back().Kind = Job::AnyExprKind; 6358 } 6359}; 6360 6361} 6362 6363bool DataRecursiveIntBinOpEvaluator:: 6364 VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, 6365 bool &SuppressRHSDiags) { 6366 if (E->getOpcode() == BO_Comma) { 6367 // Ignore LHS but note if we could not evaluate it. 6368 if (LHSResult.Failed) 6369 return Info.noteSideEffect(); 6370 return true; 6371 } 6372 6373 if (E->isLogicalOp()) { 6374 bool LHSAsBool; 6375 if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) { 6376 // We were able to evaluate the LHS, see if we can get away with not 6377 // evaluating the RHS: 0 && X -> 0, 1 || X -> 1 6378 if (LHSAsBool == (E->getOpcode() == BO_LOr)) { 6379 Success(LHSAsBool, E, LHSResult.Val); 6380 return false; // Ignore RHS 6381 } 6382 } else { 6383 LHSResult.Failed = true; 6384 6385 // Since we weren't able to evaluate the left hand side, it 6386 // must have had side effects. 6387 if (!Info.noteSideEffect()) 6388 return false; 6389 6390 // We can't evaluate the LHS; however, sometimes the result 6391 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. 6392 // Don't ignore RHS and suppress diagnostics from this arm. 6393 SuppressRHSDiags = true; 6394 } 6395 6396 return true; 6397 } 6398 6399 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && 6400 E->getRHS()->getType()->isIntegralOrEnumerationType()); 6401 6402 if (LHSResult.Failed && !Info.keepEvaluatingAfterFailure()) 6403 return false; // Ignore RHS; 6404 6405 return true; 6406} 6407 6408bool DataRecursiveIntBinOpEvaluator:: 6409 VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, 6410 const BinaryOperator *E, APValue &Result) { 6411 if (E->getOpcode() == BO_Comma) { 6412 if (RHSResult.Failed) 6413 return false; 6414 Result = RHSResult.Val; 6415 return true; 6416 } 6417 6418 if (E->isLogicalOp()) { 6419 bool lhsResult, rhsResult; 6420 bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult); 6421 bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult); 6422 6423 if (LHSIsOK) { 6424 if (RHSIsOK) { 6425 if (E->getOpcode() == BO_LOr) 6426 return Success(lhsResult || rhsResult, E, Result); 6427 else 6428 return Success(lhsResult && rhsResult, E, Result); 6429 } 6430 } else { 6431 if (RHSIsOK) { 6432 // We can't evaluate the LHS; however, sometimes the result 6433 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. 6434 if (rhsResult == (E->getOpcode() == BO_LOr)) 6435 return Success(rhsResult, E, Result); 6436 } 6437 } 6438 6439 return false; 6440 } 6441 6442 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && 6443 E->getRHS()->getType()->isIntegralOrEnumerationType()); 6444 6445 if (LHSResult.Failed || RHSResult.Failed) 6446 return false; 6447 6448 const APValue &LHSVal = LHSResult.Val; 6449 const APValue &RHSVal = RHSResult.Val; 6450 6451 // Handle cases like (unsigned long)&a + 4. 6452 if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) { 6453 Result = LHSVal; 6454 CharUnits AdditionalOffset = 6455 CharUnits::fromQuantity(RHSVal.getInt().getZExtValue()); 6456 if (E->getOpcode() == BO_Add) 6457 Result.getLValueOffset() += AdditionalOffset; 6458 else 6459 Result.getLValueOffset() -= AdditionalOffset; 6460 return true; 6461 } 6462 6463 // Handle cases like 4 + (unsigned long)&a 6464 if (E->getOpcode() == BO_Add && 6465 RHSVal.isLValue() && LHSVal.isInt()) { 6466 Result = RHSVal; 6467 Result.getLValueOffset() += 6468 CharUnits::fromQuantity(LHSVal.getInt().getZExtValue()); 6469 return true; 6470 } 6471 6472 if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) { 6473 // Handle (intptr_t)&&A - (intptr_t)&&B. 6474 if (!LHSVal.getLValueOffset().isZero() || 6475 !RHSVal.getLValueOffset().isZero()) 6476 return false; 6477 const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>(); 6478 const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>(); 6479 if (!LHSExpr || !RHSExpr) 6480 return false; 6481 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); 6482 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); 6483 if (!LHSAddrExpr || !RHSAddrExpr) 6484 return false; 6485 // Make sure both labels come from the same function. 6486 if (LHSAddrExpr->getLabel()->getDeclContext() != 6487 RHSAddrExpr->getLabel()->getDeclContext()) 6488 return false; 6489 Result = APValue(LHSAddrExpr, RHSAddrExpr); 6490 return true; 6491 } 6492 6493 // All the remaining cases expect both operands to be an integer 6494 if (!LHSVal.isInt() || !RHSVal.isInt()) 6495 return Error(E); 6496 6497 // Set up the width and signedness manually, in case it can't be deduced 6498 // from the operation we're performing. 6499 // FIXME: Don't do this in the cases where we can deduce it. 6500 APSInt Value(Info.Ctx.getIntWidth(E->getType()), 6501 E->getType()->isUnsignedIntegerOrEnumerationType()); 6502 if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(), 6503 RHSVal.getInt(), Value)) 6504 return false; 6505 return Success(Value, E, Result); 6506} 6507 6508void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) { 6509 Job &job = Queue.back(); 6510 6511 switch (job.Kind) { 6512 case Job::AnyExprKind: { 6513 if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) { 6514 if (shouldEnqueue(Bop)) { 6515 job.Kind = Job::BinOpKind; 6516 enqueue(Bop->getLHS()); 6517 return; 6518 } 6519 } 6520 6521 EvaluateExpr(job.E, Result); 6522 Queue.pop_back(); 6523 return; 6524 } 6525 6526 case Job::BinOpKind: { 6527 const BinaryOperator *Bop = cast<BinaryOperator>(job.E); 6528 bool SuppressRHSDiags = false; 6529 if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) { 6530 Queue.pop_back(); 6531 return; 6532 } 6533 if (SuppressRHSDiags) 6534 job.startSpeculativeEval(Info); 6535 job.LHSResult.swap(Result); 6536 job.Kind = Job::BinOpVisitedLHSKind; 6537 enqueue(Bop->getRHS()); 6538 return; 6539 } 6540 6541 case Job::BinOpVisitedLHSKind: { 6542 const BinaryOperator *Bop = cast<BinaryOperator>(job.E); 6543 EvalResult RHS; 6544 RHS.swap(Result); 6545 Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val); 6546 Queue.pop_back(); 6547 return; 6548 } 6549 } 6550 6551 llvm_unreachable("Invalid Job::Kind!"); 6552} 6553 6554bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 6555 if (E->isAssignmentOp()) 6556 return Error(E); 6557 6558 if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E)) 6559 return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E); 6560 6561 QualType LHSTy = E->getLHS()->getType(); 6562 QualType RHSTy = E->getRHS()->getType(); 6563 6564 if (LHSTy->isAnyComplexType()) { 6565 assert(RHSTy->isAnyComplexType() && "Invalid comparison"); 6566 ComplexValue LHS, RHS; 6567 6568 bool LHSOK = EvaluateComplex(E->getLHS(), LHS, Info); 6569 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 6570 return false; 6571 6572 if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) 6573 return false; 6574 6575 if (LHS.isComplexFloat()) { 6576 APFloat::cmpResult CR_r = 6577 LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal()); 6578 APFloat::cmpResult CR_i = 6579 LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag()); 6580 6581 if (E->getOpcode() == BO_EQ) 6582 return Success((CR_r == APFloat::cmpEqual && 6583 CR_i == APFloat::cmpEqual), E); 6584 else { 6585 assert(E->getOpcode() == BO_NE && 6586 "Invalid complex comparison."); 6587 return Success(((CR_r == APFloat::cmpGreaterThan || 6588 CR_r == APFloat::cmpLessThan || 6589 CR_r == APFloat::cmpUnordered) || 6590 (CR_i == APFloat::cmpGreaterThan || 6591 CR_i == APFloat::cmpLessThan || 6592 CR_i == APFloat::cmpUnordered)), E); 6593 } 6594 } else { 6595 if (E->getOpcode() == BO_EQ) 6596 return Success((LHS.getComplexIntReal() == RHS.getComplexIntReal() && 6597 LHS.getComplexIntImag() == RHS.getComplexIntImag()), E); 6598 else { 6599 assert(E->getOpcode() == BO_NE && 6600 "Invalid compex comparison."); 6601 return Success((LHS.getComplexIntReal() != RHS.getComplexIntReal() || 6602 LHS.getComplexIntImag() != RHS.getComplexIntImag()), E); 6603 } 6604 } 6605 } 6606 6607 if (LHSTy->isRealFloatingType() && 6608 RHSTy->isRealFloatingType()) { 6609 APFloat RHS(0.0), LHS(0.0); 6610 6611 bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info); 6612 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 6613 return false; 6614 6615 if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK) 6616 return false; 6617 6618 APFloat::cmpResult CR = LHS.compare(RHS); 6619 6620 switch (E->getOpcode()) { 6621 default: 6622 llvm_unreachable("Invalid binary operator!"); 6623 case BO_LT: 6624 return Success(CR == APFloat::cmpLessThan, E); 6625 case BO_GT: 6626 return Success(CR == APFloat::cmpGreaterThan, E); 6627 case BO_LE: 6628 return Success(CR == APFloat::cmpLessThan || CR == APFloat::cmpEqual, E); 6629 case BO_GE: 6630 return Success(CR == APFloat::cmpGreaterThan || CR == APFloat::cmpEqual, 6631 E); 6632 case BO_EQ: 6633 return Success(CR == APFloat::cmpEqual, E); 6634 case BO_NE: 6635 return Success(CR == APFloat::cmpGreaterThan 6636 || CR == APFloat::cmpLessThan 6637 || CR == APFloat::cmpUnordered, E); 6638 } 6639 } 6640 6641 if (LHSTy->isPointerType() && RHSTy->isPointerType()) { 6642 if (E->getOpcode() == BO_Sub || E->isComparisonOp()) { 6643 LValue LHSValue, RHSValue; 6644 6645 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); 6646 if (!LHSOK && Info.keepEvaluatingAfterFailure()) 6647 return false; 6648 6649 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK) 6650 return false; 6651 6652 // Reject differing bases from the normal codepath; we special-case 6653 // comparisons to null. 6654 if (!HasSameBase(LHSValue, RHSValue)) { 6655 if (E->getOpcode() == BO_Sub) { 6656 // Handle &&A - &&B. 6657 if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero()) 6658 return false; 6659 const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr*>(); 6660 const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr*>(); 6661 if (!LHSExpr || !RHSExpr) 6662 return false; 6663 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); 6664 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); 6665 if (!LHSAddrExpr || !RHSAddrExpr) 6666 return false; 6667 // Make sure both labels come from the same function. 6668 if (LHSAddrExpr->getLabel()->getDeclContext() != 6669 RHSAddrExpr->getLabel()->getDeclContext()) 6670 return false; 6671 Result = APValue(LHSAddrExpr, RHSAddrExpr); 6672 return true; 6673 } 6674 // Inequalities and subtractions between unrelated pointers have 6675 // unspecified or undefined behavior. 6676 if (!E->isEqualityOp()) 6677 return Error(E); 6678 // A constant address may compare equal to the address of a symbol. 6679 // The one exception is that address of an object cannot compare equal 6680 // to a null pointer constant. 6681 if ((!LHSValue.Base && !LHSValue.Offset.isZero()) || 6682 (!RHSValue.Base && !RHSValue.Offset.isZero())) 6683 return Error(E); 6684 // It's implementation-defined whether distinct literals will have 6685 // distinct addresses. In clang, the result of such a comparison is 6686 // unspecified, so it is not a constant expression. However, we do know 6687 // that the address of a literal will be non-null. 6688 if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) && 6689 LHSValue.Base && RHSValue.Base) 6690 return Error(E); 6691 // We can't tell whether weak symbols will end up pointing to the same 6692 // object. 6693 if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue)) 6694 return Error(E); 6695 // Pointers with different bases cannot represent the same object. 6696 // (Note that clang defaults to -fmerge-all-constants, which can 6697 // lead to inconsistent results for comparisons involving the address 6698 // of a constant; this generally doesn't matter in practice.) 6699 return Success(E->getOpcode() == BO_NE, E); 6700 } 6701 6702 const CharUnits &LHSOffset = LHSValue.getLValueOffset(); 6703 const CharUnits &RHSOffset = RHSValue.getLValueOffset(); 6704 6705 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); 6706 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); 6707 6708 if (E->getOpcode() == BO_Sub) { 6709 // C++11 [expr.add]p6: 6710 // Unless both pointers point to elements of the same array object, or 6711 // one past the last element of the array object, the behavior is 6712 // undefined. 6713 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && 6714 !AreElementsOfSameArray(getType(LHSValue.Base), 6715 LHSDesignator, RHSDesignator)) 6716 CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array); 6717 6718 QualType Type = E->getLHS()->getType(); 6719 QualType ElementType = Type->getAs<PointerType>()->getPointeeType(); 6720 6721 CharUnits ElementSize; 6722 if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize)) 6723 return false; 6724 6725 // As an extension, a type may have zero size (empty struct or union in 6726 // C, array of zero length). Pointer subtraction in such cases has 6727 // undefined behavior, so is not constant. 6728 if (ElementSize.isZero()) { 6729 Info.Diag(E, diag::note_constexpr_pointer_subtraction_zero_size) 6730 << ElementType; 6731 return false; 6732 } 6733 6734 // FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime, 6735 // and produce incorrect results when it overflows. Such behavior 6736 // appears to be non-conforming, but is common, so perhaps we should 6737 // assume the standard intended for such cases to be undefined behavior 6738 // and check for them. 6739 6740 // Compute (LHSOffset - RHSOffset) / Size carefully, checking for 6741 // overflow in the final conversion to ptrdiff_t. 6742 APSInt LHS( 6743 llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false); 6744 APSInt RHS( 6745 llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false); 6746 APSInt ElemSize( 6747 llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true), false); 6748 APSInt TrueResult = (LHS - RHS) / ElemSize; 6749 APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType())); 6750 6751 if (Result.extend(65) != TrueResult) 6752 HandleOverflow(Info, E, TrueResult, E->getType()); 6753 return Success(Result, E); 6754 } 6755 6756 // C++11 [expr.rel]p3: 6757 // Pointers to void (after pointer conversions) can be compared, with a 6758 // result defined as follows: If both pointers represent the same 6759 // address or are both the null pointer value, the result is true if the 6760 // operator is <= or >= and false otherwise; otherwise the result is 6761 // unspecified. 6762 // We interpret this as applying to pointers to *cv* void. 6763 if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && 6764 E->isRelationalOp()) 6765 CCEDiag(E, diag::note_constexpr_void_comparison); 6766 6767 // C++11 [expr.rel]p2: 6768 // - If two pointers point to non-static data members of the same object, 6769 // or to subobjects or array elements fo such members, recursively, the 6770 // pointer to the later declared member compares greater provided the 6771 // two members have the same access control and provided their class is 6772 // not a union. 6773 // [...] 6774 // - Otherwise pointer comparisons are unspecified. 6775 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && 6776 E->isRelationalOp()) { 6777 bool WasArrayIndex; 6778 unsigned Mismatch = 6779 FindDesignatorMismatch(getType(LHSValue.Base), LHSDesignator, 6780 RHSDesignator, WasArrayIndex); 6781 // At the point where the designators diverge, the comparison has a 6782 // specified value if: 6783 // - we are comparing array indices 6784 // - we are comparing fields of a union, or fields with the same access 6785 // Otherwise, the result is unspecified and thus the comparison is not a 6786 // constant expression. 6787 if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() && 6788 Mismatch < RHSDesignator.Entries.size()) { 6789 const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]); 6790 const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]); 6791 if (!LF && !RF) 6792 CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes); 6793 else if (!LF) 6794 CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) 6795 << getAsBaseClass(LHSDesignator.Entries[Mismatch]) 6796 << RF->getParent() << RF; 6797 else if (!RF) 6798 CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) 6799 << getAsBaseClass(RHSDesignator.Entries[Mismatch]) 6800 << LF->getParent() << LF; 6801 else if (!LF->getParent()->isUnion() && 6802 LF->getAccess() != RF->getAccess()) 6803 CCEDiag(E, diag::note_constexpr_pointer_comparison_differing_access) 6804 << LF << LF->getAccess() << RF << RF->getAccess() 6805 << LF->getParent(); 6806 } 6807 } 6808 6809 // The comparison here must be unsigned, and performed with the same 6810 // width as the pointer. 6811 unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy); 6812 uint64_t CompareLHS = LHSOffset.getQuantity(); 6813 uint64_t CompareRHS = RHSOffset.getQuantity(); 6814 assert(PtrSize <= 64 && "Unexpected pointer width"); 6815 uint64_t Mask = ~0ULL >> (64 - PtrSize); 6816 CompareLHS &= Mask; 6817 CompareRHS &= Mask; 6818 6819 // If there is a base and this is a relational operator, we can only 6820 // compare pointers within the object in question; otherwise, the result 6821 // depends on where the object is located in memory. 6822 if (!LHSValue.Base.isNull() && E->isRelationalOp()) { 6823 QualType BaseTy = getType(LHSValue.Base); 6824 if (BaseTy->isIncompleteType()) 6825 return Error(E); 6826 CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy); 6827 uint64_t OffsetLimit = Size.getQuantity(); 6828 if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit) 6829 return Error(E); 6830 } 6831 6832 switch (E->getOpcode()) { 6833 default: llvm_unreachable("missing comparison operator"); 6834 case BO_LT: return Success(CompareLHS < CompareRHS, E); 6835 case BO_GT: return Success(CompareLHS > CompareRHS, E); 6836 case BO_LE: return Success(CompareLHS <= CompareRHS, E); 6837 case BO_GE: return Success(CompareLHS >= CompareRHS, E); 6838 case BO_EQ: return Success(CompareLHS == CompareRHS, E); 6839 case BO_NE: return Success(CompareLHS != CompareRHS, E); 6840 } 6841 } 6842 } 6843 6844 if (LHSTy->isMemberPointerType()) { 6845 assert(E->isEqualityOp() && "unexpected member pointer operation"); 6846 assert(RHSTy->isMemberPointerType() && "invalid comparison"); 6847 6848 MemberPtr LHSValue, RHSValue; 6849 6850 bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info); 6851 if (!LHSOK && Info.keepEvaluatingAfterFailure()) 6852 return false; 6853 6854 if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK) 6855 return false; 6856 6857 // C++11 [expr.eq]p2: 6858 // If both operands are null, they compare equal. Otherwise if only one is 6859 // null, they compare unequal. 6860 if (!LHSValue.getDecl() || !RHSValue.getDecl()) { 6861 bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl(); 6862 return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E); 6863 } 6864 6865 // Otherwise if either is a pointer to a virtual member function, the 6866 // result is unspecified. 6867 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl())) 6868 if (MD->isVirtual()) 6869 CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; 6870 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl())) 6871 if (MD->isVirtual()) 6872 CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; 6873 6874 // Otherwise they compare equal if and only if they would refer to the 6875 // same member of the same most derived object or the same subobject if 6876 // they were dereferenced with a hypothetical object of the associated 6877 // class type. 6878 bool Equal = LHSValue == RHSValue; 6879 return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E); 6880 } 6881 6882 if (LHSTy->isNullPtrType()) { 6883 assert(E->isComparisonOp() && "unexpected nullptr operation"); 6884 assert(RHSTy->isNullPtrType() && "missing pointer conversion"); 6885 // C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t 6886 // are compared, the result is true of the operator is <=, >= or ==, and 6887 // false otherwise. 6888 BinaryOperator::Opcode Opcode = E->getOpcode(); 6889 return Success(Opcode == BO_EQ || Opcode == BO_LE || Opcode == BO_GE, E); 6890 } 6891 6892 assert((!LHSTy->isIntegralOrEnumerationType() || 6893 !RHSTy->isIntegralOrEnumerationType()) && 6894 "DataRecursiveIntBinOpEvaluator should have handled integral types"); 6895 // We can't continue from here for non-integral types. 6896 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 6897} 6898 6899CharUnits IntExprEvaluator::GetAlignOfType(QualType T) { 6900 // C++ [expr.alignof]p3: "When alignof is applied to a reference type, the 6901 // result shall be the alignment of the referenced type." 6902 if (const ReferenceType *Ref = T->getAs<ReferenceType>()) 6903 T = Ref->getPointeeType(); 6904 6905 // __alignof is defined to return the preferred alignment. 6906 return Info.Ctx.toCharUnitsFromBits( 6907 Info.Ctx.getPreferredTypeAlign(T.getTypePtr())); 6908} 6909 6910CharUnits IntExprEvaluator::GetAlignOfExpr(const Expr *E) { 6911 E = E->IgnoreParens(); 6912 6913 // The kinds of expressions that we have special-case logic here for 6914 // should be kept up to date with the special checks for those 6915 // expressions in Sema. 6916 6917 // alignof decl is always accepted, even if it doesn't make sense: we default 6918 // to 1 in those cases. 6919 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) 6920 return Info.Ctx.getDeclAlign(DRE->getDecl(), 6921 /*RefAsPointee*/true); 6922 6923 if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) 6924 return Info.Ctx.getDeclAlign(ME->getMemberDecl(), 6925 /*RefAsPointee*/true); 6926 6927 return GetAlignOfType(E->getType()); 6928} 6929 6930 6931/// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with 6932/// a result as the expression's type. 6933bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr( 6934 const UnaryExprOrTypeTraitExpr *E) { 6935 switch(E->getKind()) { 6936 case UETT_AlignOf: { 6937 if (E->isArgumentType()) 6938 return Success(GetAlignOfType(E->getArgumentType()), E); 6939 else 6940 return Success(GetAlignOfExpr(E->getArgumentExpr()), E); 6941 } 6942 6943 case UETT_VecStep: { 6944 QualType Ty = E->getTypeOfArgument(); 6945 6946 if (Ty->isVectorType()) { 6947 unsigned n = Ty->castAs<VectorType>()->getNumElements(); 6948 6949 // The vec_step built-in functions that take a 3-component 6950 // vector return 4. (OpenCL 1.1 spec 6.11.12) 6951 if (n == 3) 6952 n = 4; 6953 6954 return Success(n, E); 6955 } else 6956 return Success(1, E); 6957 } 6958 6959 case UETT_SizeOf: { 6960 QualType SrcTy = E->getTypeOfArgument(); 6961 // C++ [expr.sizeof]p2: "When applied to a reference or a reference type, 6962 // the result is the size of the referenced type." 6963 if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>()) 6964 SrcTy = Ref->getPointeeType(); 6965 6966 CharUnits Sizeof; 6967 if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof)) 6968 return false; 6969 return Success(Sizeof, E); 6970 } 6971 } 6972 6973 llvm_unreachable("unknown expr/type trait"); 6974} 6975 6976bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) { 6977 CharUnits Result; 6978 unsigned n = OOE->getNumComponents(); 6979 if (n == 0) 6980 return Error(OOE); 6981 QualType CurrentType = OOE->getTypeSourceInfo()->getType(); 6982 for (unsigned i = 0; i != n; ++i) { 6983 OffsetOfExpr::OffsetOfNode ON = OOE->getComponent(i); 6984 switch (ON.getKind()) { 6985 case OffsetOfExpr::OffsetOfNode::Array: { 6986 const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex()); 6987 APSInt IdxResult; 6988 if (!EvaluateInteger(Idx, IdxResult, Info)) 6989 return false; 6990 const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType); 6991 if (!AT) 6992 return Error(OOE); 6993 CurrentType = AT->getElementType(); 6994 CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType); 6995 Result += IdxResult.getSExtValue() * ElementSize; 6996 break; 6997 } 6998 6999 case OffsetOfExpr::OffsetOfNode::Field: { 7000 FieldDecl *MemberDecl = ON.getField(); 7001 const RecordType *RT = CurrentType->getAs<RecordType>(); 7002 if (!RT) 7003 return Error(OOE); 7004 RecordDecl *RD = RT->getDecl(); 7005 if (RD->isInvalidDecl()) return false; 7006 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); 7007 unsigned i = MemberDecl->getFieldIndex(); 7008 assert(i < RL.getFieldCount() && "offsetof field in wrong type"); 7009 Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i)); 7010 CurrentType = MemberDecl->getType().getNonReferenceType(); 7011 break; 7012 } 7013 7014 case OffsetOfExpr::OffsetOfNode::Identifier: 7015 llvm_unreachable("dependent __builtin_offsetof"); 7016 7017 case OffsetOfExpr::OffsetOfNode::Base: { 7018 CXXBaseSpecifier *BaseSpec = ON.getBase(); 7019 if (BaseSpec->isVirtual()) 7020 return Error(OOE); 7021 7022 // Find the layout of the class whose base we are looking into. 7023 const RecordType *RT = CurrentType->getAs<RecordType>(); 7024 if (!RT) 7025 return Error(OOE); 7026 RecordDecl *RD = RT->getDecl(); 7027 if (RD->isInvalidDecl()) return false; 7028 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); 7029 7030 // Find the base class itself. 7031 CurrentType = BaseSpec->getType(); 7032 const RecordType *BaseRT = CurrentType->getAs<RecordType>(); 7033 if (!BaseRT) 7034 return Error(OOE); 7035 7036 // Add the offset to the base. 7037 Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl())); 7038 break; 7039 } 7040 } 7041 } 7042 return Success(Result, OOE); 7043} 7044 7045bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 7046 switch (E->getOpcode()) { 7047 default: 7048 // Address, indirect, pre/post inc/dec, etc are not valid constant exprs. 7049 // See C99 6.6p3. 7050 return Error(E); 7051 case UO_Extension: 7052 // FIXME: Should extension allow i-c-e extension expressions in its scope? 7053 // If so, we could clear the diagnostic ID. 7054 return Visit(E->getSubExpr()); 7055 case UO_Plus: 7056 // The result is just the value. 7057 return Visit(E->getSubExpr()); 7058 case UO_Minus: { 7059 if (!Visit(E->getSubExpr())) 7060 return false; 7061 if (!Result.isInt()) return Error(E); 7062 const APSInt &Value = Result.getInt(); 7063 if (Value.isSigned() && Value.isMinSignedValue()) 7064 HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1), 7065 E->getType()); 7066 return Success(-Value, E); 7067 } 7068 case UO_Not: { 7069 if (!Visit(E->getSubExpr())) 7070 return false; 7071 if (!Result.isInt()) return Error(E); 7072 return Success(~Result.getInt(), E); 7073 } 7074 case UO_LNot: { 7075 bool bres; 7076 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info)) 7077 return false; 7078 return Success(!bres, E); 7079 } 7080 } 7081} 7082 7083/// HandleCast - This is used to evaluate implicit or explicit casts where the 7084/// result type is integer. 7085bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) { 7086 const Expr *SubExpr = E->getSubExpr(); 7087 QualType DestType = E->getType(); 7088 QualType SrcType = SubExpr->getType(); 7089 7090 switch (E->getCastKind()) { 7091 case CK_BaseToDerived: 7092 case CK_DerivedToBase: 7093 case CK_UncheckedDerivedToBase: 7094 case CK_Dynamic: 7095 case CK_ToUnion: 7096 case CK_ArrayToPointerDecay: 7097 case CK_FunctionToPointerDecay: 7098 case CK_NullToPointer: 7099 case CK_NullToMemberPointer: 7100 case CK_BaseToDerivedMemberPointer: 7101 case CK_DerivedToBaseMemberPointer: 7102 case CK_ReinterpretMemberPointer: 7103 case CK_ConstructorConversion: 7104 case CK_IntegralToPointer: 7105 case CK_ToVoid: 7106 case CK_VectorSplat: 7107 case CK_IntegralToFloating: 7108 case CK_FloatingCast: 7109 case CK_CPointerToObjCPointerCast: 7110 case CK_BlockPointerToObjCPointerCast: 7111 case CK_AnyPointerToBlockPointerCast: 7112 case CK_ObjCObjectLValueCast: 7113 case CK_FloatingRealToComplex: 7114 case CK_FloatingComplexToReal: 7115 case CK_FloatingComplexCast: 7116 case CK_FloatingComplexToIntegralComplex: 7117 case CK_IntegralRealToComplex: 7118 case CK_IntegralComplexCast: 7119 case CK_IntegralComplexToFloatingComplex: 7120 case CK_BuiltinFnToFnPtr: 7121 case CK_ZeroToOCLEvent: 7122 case CK_NonAtomicToAtomic: 7123 llvm_unreachable("invalid cast kind for integral value"); 7124 7125 case CK_BitCast: 7126 case CK_Dependent: 7127 case CK_LValueBitCast: 7128 case CK_ARCProduceObject: 7129 case CK_ARCConsumeObject: 7130 case CK_ARCReclaimReturnedObject: 7131 case CK_ARCExtendBlockObject: 7132 case CK_CopyAndAutoreleaseBlockObject: 7133 return Error(E); 7134 7135 case CK_UserDefinedConversion: 7136 case CK_LValueToRValue: 7137 case CK_AtomicToNonAtomic: 7138 case CK_NoOp: 7139 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7140 7141 case CK_MemberPointerToBoolean: 7142 case CK_PointerToBoolean: 7143 case CK_IntegralToBoolean: 7144 case CK_FloatingToBoolean: 7145 case CK_FloatingComplexToBoolean: 7146 case CK_IntegralComplexToBoolean: { 7147 bool BoolResult; 7148 if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info)) 7149 return false; 7150 return Success(BoolResult, E); 7151 } 7152 7153 case CK_IntegralCast: { 7154 if (!Visit(SubExpr)) 7155 return false; 7156 7157 if (!Result.isInt()) { 7158 // Allow casts of address-of-label differences if they are no-ops 7159 // or narrowing. (The narrowing case isn't actually guaranteed to 7160 // be constant-evaluatable except in some narrow cases which are hard 7161 // to detect here. We let it through on the assumption the user knows 7162 // what they are doing.) 7163 if (Result.isAddrLabelDiff()) 7164 return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType); 7165 // Only allow casts of lvalues if they are lossless. 7166 return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType); 7167 } 7168 7169 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, 7170 Result.getInt()), E); 7171 } 7172 7173 case CK_PointerToIntegral: { 7174 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 7175 7176 LValue LV; 7177 if (!EvaluatePointer(SubExpr, LV, Info)) 7178 return false; 7179 7180 if (LV.getLValueBase()) { 7181 // Only allow based lvalue casts if they are lossless. 7182 // FIXME: Allow a larger integer size than the pointer size, and allow 7183 // narrowing back down to pointer width in subsequent integral casts. 7184 // FIXME: Check integer type's active bits, not its type size. 7185 if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType)) 7186 return Error(E); 7187 7188 LV.Designator.setInvalid(); 7189 LV.moveInto(Result); 7190 return true; 7191 } 7192 7193 APSInt AsInt = Info.Ctx.MakeIntValue(LV.getLValueOffset().getQuantity(), 7194 SrcType); 7195 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E); 7196 } 7197 7198 case CK_IntegralComplexToReal: { 7199 ComplexValue C; 7200 if (!EvaluateComplex(SubExpr, C, Info)) 7201 return false; 7202 return Success(C.getComplexIntReal(), E); 7203 } 7204 7205 case CK_FloatingToIntegral: { 7206 APFloat F(0.0); 7207 if (!EvaluateFloat(SubExpr, F, Info)) 7208 return false; 7209 7210 APSInt Value; 7211 if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value)) 7212 return false; 7213 return Success(Value, E); 7214 } 7215 } 7216 7217 llvm_unreachable("unknown cast resulting in integral value"); 7218} 7219 7220bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 7221 if (E->getSubExpr()->getType()->isAnyComplexType()) { 7222 ComplexValue LV; 7223 if (!EvaluateComplex(E->getSubExpr(), LV, Info)) 7224 return false; 7225 if (!LV.isComplexInt()) 7226 return Error(E); 7227 return Success(LV.getComplexIntReal(), E); 7228 } 7229 7230 return Visit(E->getSubExpr()); 7231} 7232 7233bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 7234 if (E->getSubExpr()->getType()->isComplexIntegerType()) { 7235 ComplexValue LV; 7236 if (!EvaluateComplex(E->getSubExpr(), LV, Info)) 7237 return false; 7238 if (!LV.isComplexInt()) 7239 return Error(E); 7240 return Success(LV.getComplexIntImag(), E); 7241 } 7242 7243 VisitIgnoredValue(E->getSubExpr()); 7244 return Success(0, E); 7245} 7246 7247bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) { 7248 return Success(E->getPackLength(), E); 7249} 7250 7251bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) { 7252 return Success(E->getValue(), E); 7253} 7254 7255//===----------------------------------------------------------------------===// 7256// Float Evaluation 7257//===----------------------------------------------------------------------===// 7258 7259namespace { 7260class FloatExprEvaluator 7261 : public ExprEvaluatorBase<FloatExprEvaluator, bool> { 7262 APFloat &Result; 7263public: 7264 FloatExprEvaluator(EvalInfo &info, APFloat &result) 7265 : ExprEvaluatorBaseTy(info), Result(result) {} 7266 7267 bool Success(const APValue &V, const Expr *e) { 7268 Result = V.getFloat(); 7269 return true; 7270 } 7271 7272 bool ZeroInitialization(const Expr *E) { 7273 Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType())); 7274 return true; 7275 } 7276 7277 bool VisitCallExpr(const CallExpr *E); 7278 7279 bool VisitUnaryOperator(const UnaryOperator *E); 7280 bool VisitBinaryOperator(const BinaryOperator *E); 7281 bool VisitFloatingLiteral(const FloatingLiteral *E); 7282 bool VisitCastExpr(const CastExpr *E); 7283 7284 bool VisitUnaryReal(const UnaryOperator *E); 7285 bool VisitUnaryImag(const UnaryOperator *E); 7286 7287 // FIXME: Missing: array subscript of vector, member of vector 7288}; 7289} // end anonymous namespace 7290 7291static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) { 7292 assert(E->isRValue() && E->getType()->isRealFloatingType()); 7293 return FloatExprEvaluator(Info, Result).Visit(E); 7294} 7295 7296static bool TryEvaluateBuiltinNaN(const ASTContext &Context, 7297 QualType ResultTy, 7298 const Expr *Arg, 7299 bool SNaN, 7300 llvm::APFloat &Result) { 7301 const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts()); 7302 if (!S) return false; 7303 7304 const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy); 7305 7306 llvm::APInt fill; 7307 7308 // Treat empty strings as if they were zero. 7309 if (S->getString().empty()) 7310 fill = llvm::APInt(32, 0); 7311 else if (S->getString().getAsInteger(0, fill)) 7312 return false; 7313 7314 if (SNaN) 7315 Result = llvm::APFloat::getSNaN(Sem, false, &fill); 7316 else 7317 Result = llvm::APFloat::getQNaN(Sem, false, &fill); 7318 return true; 7319} 7320 7321bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) { 7322 switch (E->isBuiltinCall()) { 7323 default: 7324 return ExprEvaluatorBaseTy::VisitCallExpr(E); 7325 7326 case Builtin::BI__builtin_huge_val: 7327 case Builtin::BI__builtin_huge_valf: 7328 case Builtin::BI__builtin_huge_vall: 7329 case Builtin::BI__builtin_inf: 7330 case Builtin::BI__builtin_inff: 7331 case Builtin::BI__builtin_infl: { 7332 const llvm::fltSemantics &Sem = 7333 Info.Ctx.getFloatTypeSemantics(E->getType()); 7334 Result = llvm::APFloat::getInf(Sem); 7335 return true; 7336 } 7337 7338 case Builtin::BI__builtin_nans: 7339 case Builtin::BI__builtin_nansf: 7340 case Builtin::BI__builtin_nansl: 7341 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), 7342 true, Result)) 7343 return Error(E); 7344 return true; 7345 7346 case Builtin::BI__builtin_nan: 7347 case Builtin::BI__builtin_nanf: 7348 case Builtin::BI__builtin_nanl: 7349 // If this is __builtin_nan() turn this into a nan, otherwise we 7350 // can't constant fold it. 7351 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), 7352 false, Result)) 7353 return Error(E); 7354 return true; 7355 7356 case Builtin::BI__builtin_fabs: 7357 case Builtin::BI__builtin_fabsf: 7358 case Builtin::BI__builtin_fabsl: 7359 if (!EvaluateFloat(E->getArg(0), Result, Info)) 7360 return false; 7361 7362 if (Result.isNegative()) 7363 Result.changeSign(); 7364 return true; 7365 7366 // FIXME: Builtin::BI__builtin_powi 7367 // FIXME: Builtin::BI__builtin_powif 7368 // FIXME: Builtin::BI__builtin_powil 7369 7370 case Builtin::BI__builtin_copysign: 7371 case Builtin::BI__builtin_copysignf: 7372 case Builtin::BI__builtin_copysignl: { 7373 APFloat RHS(0.); 7374 if (!EvaluateFloat(E->getArg(0), Result, Info) || 7375 !EvaluateFloat(E->getArg(1), RHS, Info)) 7376 return false; 7377 Result.copySign(RHS); 7378 return true; 7379 } 7380 } 7381} 7382 7383bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 7384 if (E->getSubExpr()->getType()->isAnyComplexType()) { 7385 ComplexValue CV; 7386 if (!EvaluateComplex(E->getSubExpr(), CV, Info)) 7387 return false; 7388 Result = CV.FloatReal; 7389 return true; 7390 } 7391 7392 return Visit(E->getSubExpr()); 7393} 7394 7395bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 7396 if (E->getSubExpr()->getType()->isAnyComplexType()) { 7397 ComplexValue CV; 7398 if (!EvaluateComplex(E->getSubExpr(), CV, Info)) 7399 return false; 7400 Result = CV.FloatImag; 7401 return true; 7402 } 7403 7404 VisitIgnoredValue(E->getSubExpr()); 7405 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType()); 7406 Result = llvm::APFloat::getZero(Sem); 7407 return true; 7408} 7409 7410bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 7411 switch (E->getOpcode()) { 7412 default: return Error(E); 7413 case UO_Plus: 7414 return EvaluateFloat(E->getSubExpr(), Result, Info); 7415 case UO_Minus: 7416 if (!EvaluateFloat(E->getSubExpr(), Result, Info)) 7417 return false; 7418 Result.changeSign(); 7419 return true; 7420 } 7421} 7422 7423bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 7424 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) 7425 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 7426 7427 APFloat RHS(0.0); 7428 bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info); 7429 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 7430 return false; 7431 return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK && 7432 handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS); 7433} 7434 7435bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) { 7436 Result = E->getValue(); 7437 return true; 7438} 7439 7440bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) { 7441 const Expr* SubExpr = E->getSubExpr(); 7442 7443 switch (E->getCastKind()) { 7444 default: 7445 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7446 7447 case CK_IntegralToFloating: { 7448 APSInt IntResult; 7449 return EvaluateInteger(SubExpr, IntResult, Info) && 7450 HandleIntToFloatCast(Info, E, SubExpr->getType(), IntResult, 7451 E->getType(), Result); 7452 } 7453 7454 case CK_FloatingCast: { 7455 if (!Visit(SubExpr)) 7456 return false; 7457 return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(), 7458 Result); 7459 } 7460 7461 case CK_FloatingComplexToReal: { 7462 ComplexValue V; 7463 if (!EvaluateComplex(SubExpr, V, Info)) 7464 return false; 7465 Result = V.getComplexFloatReal(); 7466 return true; 7467 } 7468 } 7469} 7470 7471//===----------------------------------------------------------------------===// 7472// Complex Evaluation (for float and integer) 7473//===----------------------------------------------------------------------===// 7474 7475namespace { 7476class ComplexExprEvaluator 7477 : public ExprEvaluatorBase<ComplexExprEvaluator, bool> { 7478 ComplexValue &Result; 7479 7480public: 7481 ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result) 7482 : ExprEvaluatorBaseTy(info), Result(Result) {} 7483 7484 bool Success(const APValue &V, const Expr *e) { 7485 Result.setFrom(V); 7486 return true; 7487 } 7488 7489 bool ZeroInitialization(const Expr *E); 7490 7491 //===--------------------------------------------------------------------===// 7492 // Visitor Methods 7493 //===--------------------------------------------------------------------===// 7494 7495 bool VisitImaginaryLiteral(const ImaginaryLiteral *E); 7496 bool VisitCastExpr(const CastExpr *E); 7497 bool VisitBinaryOperator(const BinaryOperator *E); 7498 bool VisitUnaryOperator(const UnaryOperator *E); 7499 bool VisitInitListExpr(const InitListExpr *E); 7500}; 7501} // end anonymous namespace 7502 7503static bool EvaluateComplex(const Expr *E, ComplexValue &Result, 7504 EvalInfo &Info) { 7505 assert(E->isRValue() && E->getType()->isAnyComplexType()); 7506 return ComplexExprEvaluator(Info, Result).Visit(E); 7507} 7508 7509bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) { 7510 QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType(); 7511 if (ElemTy->isRealFloatingType()) { 7512 Result.makeComplexFloat(); 7513 APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy)); 7514 Result.FloatReal = Zero; 7515 Result.FloatImag = Zero; 7516 } else { 7517 Result.makeComplexInt(); 7518 APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy); 7519 Result.IntReal = Zero; 7520 Result.IntImag = Zero; 7521 } 7522 return true; 7523} 7524 7525bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) { 7526 const Expr* SubExpr = E->getSubExpr(); 7527 7528 if (SubExpr->getType()->isRealFloatingType()) { 7529 Result.makeComplexFloat(); 7530 APFloat &Imag = Result.FloatImag; 7531 if (!EvaluateFloat(SubExpr, Imag, Info)) 7532 return false; 7533 7534 Result.FloatReal = APFloat(Imag.getSemantics()); 7535 return true; 7536 } else { 7537 assert(SubExpr->getType()->isIntegerType() && 7538 "Unexpected imaginary literal."); 7539 7540 Result.makeComplexInt(); 7541 APSInt &Imag = Result.IntImag; 7542 if (!EvaluateInteger(SubExpr, Imag, Info)) 7543 return false; 7544 7545 Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned()); 7546 return true; 7547 } 7548} 7549 7550bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) { 7551 7552 switch (E->getCastKind()) { 7553 case CK_BitCast: 7554 case CK_BaseToDerived: 7555 case CK_DerivedToBase: 7556 case CK_UncheckedDerivedToBase: 7557 case CK_Dynamic: 7558 case CK_ToUnion: 7559 case CK_ArrayToPointerDecay: 7560 case CK_FunctionToPointerDecay: 7561 case CK_NullToPointer: 7562 case CK_NullToMemberPointer: 7563 case CK_BaseToDerivedMemberPointer: 7564 case CK_DerivedToBaseMemberPointer: 7565 case CK_MemberPointerToBoolean: 7566 case CK_ReinterpretMemberPointer: 7567 case CK_ConstructorConversion: 7568 case CK_IntegralToPointer: 7569 case CK_PointerToIntegral: 7570 case CK_PointerToBoolean: 7571 case CK_ToVoid: 7572 case CK_VectorSplat: 7573 case CK_IntegralCast: 7574 case CK_IntegralToBoolean: 7575 case CK_IntegralToFloating: 7576 case CK_FloatingToIntegral: 7577 case CK_FloatingToBoolean: 7578 case CK_FloatingCast: 7579 case CK_CPointerToObjCPointerCast: 7580 case CK_BlockPointerToObjCPointerCast: 7581 case CK_AnyPointerToBlockPointerCast: 7582 case CK_ObjCObjectLValueCast: 7583 case CK_FloatingComplexToReal: 7584 case CK_FloatingComplexToBoolean: 7585 case CK_IntegralComplexToReal: 7586 case CK_IntegralComplexToBoolean: 7587 case CK_ARCProduceObject: 7588 case CK_ARCConsumeObject: 7589 case CK_ARCReclaimReturnedObject: 7590 case CK_ARCExtendBlockObject: 7591 case CK_CopyAndAutoreleaseBlockObject: 7592 case CK_BuiltinFnToFnPtr: 7593 case CK_ZeroToOCLEvent: 7594 case CK_NonAtomicToAtomic: 7595 llvm_unreachable("invalid cast kind for complex value"); 7596 7597 case CK_LValueToRValue: 7598 case CK_AtomicToNonAtomic: 7599 case CK_NoOp: 7600 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7601 7602 case CK_Dependent: 7603 case CK_LValueBitCast: 7604 case CK_UserDefinedConversion: 7605 return Error(E); 7606 7607 case CK_FloatingRealToComplex: { 7608 APFloat &Real = Result.FloatReal; 7609 if (!EvaluateFloat(E->getSubExpr(), Real, Info)) 7610 return false; 7611 7612 Result.makeComplexFloat(); 7613 Result.FloatImag = APFloat(Real.getSemantics()); 7614 return true; 7615 } 7616 7617 case CK_FloatingComplexCast: { 7618 if (!Visit(E->getSubExpr())) 7619 return false; 7620 7621 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 7622 QualType From 7623 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 7624 7625 return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) && 7626 HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag); 7627 } 7628 7629 case CK_FloatingComplexToIntegralComplex: { 7630 if (!Visit(E->getSubExpr())) 7631 return false; 7632 7633 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 7634 QualType From 7635 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 7636 Result.makeComplexInt(); 7637 return HandleFloatToIntCast(Info, E, From, Result.FloatReal, 7638 To, Result.IntReal) && 7639 HandleFloatToIntCast(Info, E, From, Result.FloatImag, 7640 To, Result.IntImag); 7641 } 7642 7643 case CK_IntegralRealToComplex: { 7644 APSInt &Real = Result.IntReal; 7645 if (!EvaluateInteger(E->getSubExpr(), Real, Info)) 7646 return false; 7647 7648 Result.makeComplexInt(); 7649 Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned()); 7650 return true; 7651 } 7652 7653 case CK_IntegralComplexCast: { 7654 if (!Visit(E->getSubExpr())) 7655 return false; 7656 7657 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 7658 QualType From 7659 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 7660 7661 Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal); 7662 Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag); 7663 return true; 7664 } 7665 7666 case CK_IntegralComplexToFloatingComplex: { 7667 if (!Visit(E->getSubExpr())) 7668 return false; 7669 7670 QualType To = E->getType()->castAs<ComplexType>()->getElementType(); 7671 QualType From 7672 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType(); 7673 Result.makeComplexFloat(); 7674 return HandleIntToFloatCast(Info, E, From, Result.IntReal, 7675 To, Result.FloatReal) && 7676 HandleIntToFloatCast(Info, E, From, Result.IntImag, 7677 To, Result.FloatImag); 7678 } 7679 } 7680 7681 llvm_unreachable("unknown cast resulting in complex value"); 7682} 7683 7684bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 7685 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) 7686 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 7687 7688 bool LHSOK = Visit(E->getLHS()); 7689 if (!LHSOK && !Info.keepEvaluatingAfterFailure()) 7690 return false; 7691 7692 ComplexValue RHS; 7693 if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) 7694 return false; 7695 7696 assert(Result.isComplexFloat() == RHS.isComplexFloat() && 7697 "Invalid operands to binary operator."); 7698 switch (E->getOpcode()) { 7699 default: return Error(E); 7700 case BO_Add: 7701 if (Result.isComplexFloat()) { 7702 Result.getComplexFloatReal().add(RHS.getComplexFloatReal(), 7703 APFloat::rmNearestTiesToEven); 7704 Result.getComplexFloatImag().add(RHS.getComplexFloatImag(), 7705 APFloat::rmNearestTiesToEven); 7706 } else { 7707 Result.getComplexIntReal() += RHS.getComplexIntReal(); 7708 Result.getComplexIntImag() += RHS.getComplexIntImag(); 7709 } 7710 break; 7711 case BO_Sub: 7712 if (Result.isComplexFloat()) { 7713 Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(), 7714 APFloat::rmNearestTiesToEven); 7715 Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(), 7716 APFloat::rmNearestTiesToEven); 7717 } else { 7718 Result.getComplexIntReal() -= RHS.getComplexIntReal(); 7719 Result.getComplexIntImag() -= RHS.getComplexIntImag(); 7720 } 7721 break; 7722 case BO_Mul: 7723 if (Result.isComplexFloat()) { 7724 ComplexValue LHS = Result; 7725 APFloat &LHS_r = LHS.getComplexFloatReal(); 7726 APFloat &LHS_i = LHS.getComplexFloatImag(); 7727 APFloat &RHS_r = RHS.getComplexFloatReal(); 7728 APFloat &RHS_i = RHS.getComplexFloatImag(); 7729 7730 APFloat Tmp = LHS_r; 7731 Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven); 7732 Result.getComplexFloatReal() = Tmp; 7733 Tmp = LHS_i; 7734 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 7735 Result.getComplexFloatReal().subtract(Tmp, APFloat::rmNearestTiesToEven); 7736 7737 Tmp = LHS_r; 7738 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 7739 Result.getComplexFloatImag() = Tmp; 7740 Tmp = LHS_i; 7741 Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven); 7742 Result.getComplexFloatImag().add(Tmp, APFloat::rmNearestTiesToEven); 7743 } else { 7744 ComplexValue LHS = Result; 7745 Result.getComplexIntReal() = 7746 (LHS.getComplexIntReal() * RHS.getComplexIntReal() - 7747 LHS.getComplexIntImag() * RHS.getComplexIntImag()); 7748 Result.getComplexIntImag() = 7749 (LHS.getComplexIntReal() * RHS.getComplexIntImag() + 7750 LHS.getComplexIntImag() * RHS.getComplexIntReal()); 7751 } 7752 break; 7753 case BO_Div: 7754 if (Result.isComplexFloat()) { 7755 ComplexValue LHS = Result; 7756 APFloat &LHS_r = LHS.getComplexFloatReal(); 7757 APFloat &LHS_i = LHS.getComplexFloatImag(); 7758 APFloat &RHS_r = RHS.getComplexFloatReal(); 7759 APFloat &RHS_i = RHS.getComplexFloatImag(); 7760 APFloat &Res_r = Result.getComplexFloatReal(); 7761 APFloat &Res_i = Result.getComplexFloatImag(); 7762 7763 APFloat Den = RHS_r; 7764 Den.multiply(RHS_r, APFloat::rmNearestTiesToEven); 7765 APFloat Tmp = RHS_i; 7766 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 7767 Den.add(Tmp, APFloat::rmNearestTiesToEven); 7768 7769 Res_r = LHS_r; 7770 Res_r.multiply(RHS_r, APFloat::rmNearestTiesToEven); 7771 Tmp = LHS_i; 7772 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 7773 Res_r.add(Tmp, APFloat::rmNearestTiesToEven); 7774 Res_r.divide(Den, APFloat::rmNearestTiesToEven); 7775 7776 Res_i = LHS_i; 7777 Res_i.multiply(RHS_r, APFloat::rmNearestTiesToEven); 7778 Tmp = LHS_r; 7779 Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven); 7780 Res_i.subtract(Tmp, APFloat::rmNearestTiesToEven); 7781 Res_i.divide(Den, APFloat::rmNearestTiesToEven); 7782 } else { 7783 if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0) 7784 return Error(E, diag::note_expr_divide_by_zero); 7785 7786 ComplexValue LHS = Result; 7787 APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() + 7788 RHS.getComplexIntImag() * RHS.getComplexIntImag(); 7789 Result.getComplexIntReal() = 7790 (LHS.getComplexIntReal() * RHS.getComplexIntReal() + 7791 LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den; 7792 Result.getComplexIntImag() = 7793 (LHS.getComplexIntImag() * RHS.getComplexIntReal() - 7794 LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den; 7795 } 7796 break; 7797 } 7798 7799 return true; 7800} 7801 7802bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 7803 // Get the operand value into 'Result'. 7804 if (!Visit(E->getSubExpr())) 7805 return false; 7806 7807 switch (E->getOpcode()) { 7808 default: 7809 return Error(E); 7810 case UO_Extension: 7811 return true; 7812 case UO_Plus: 7813 // The result is always just the subexpr. 7814 return true; 7815 case UO_Minus: 7816 if (Result.isComplexFloat()) { 7817 Result.getComplexFloatReal().changeSign(); 7818 Result.getComplexFloatImag().changeSign(); 7819 } 7820 else { 7821 Result.getComplexIntReal() = -Result.getComplexIntReal(); 7822 Result.getComplexIntImag() = -Result.getComplexIntImag(); 7823 } 7824 return true; 7825 case UO_Not: 7826 if (Result.isComplexFloat()) 7827 Result.getComplexFloatImag().changeSign(); 7828 else 7829 Result.getComplexIntImag() = -Result.getComplexIntImag(); 7830 return true; 7831 } 7832} 7833 7834bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 7835 if (E->getNumInits() == 2) { 7836 if (E->getType()->isComplexType()) { 7837 Result.makeComplexFloat(); 7838 if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info)) 7839 return false; 7840 if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info)) 7841 return false; 7842 } else { 7843 Result.makeComplexInt(); 7844 if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info)) 7845 return false; 7846 if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info)) 7847 return false; 7848 } 7849 return true; 7850 } 7851 return ExprEvaluatorBaseTy::VisitInitListExpr(E); 7852} 7853 7854//===----------------------------------------------------------------------===// 7855// Atomic expression evaluation, essentially just handling the NonAtomicToAtomic 7856// implicit conversion. 7857//===----------------------------------------------------------------------===// 7858 7859namespace { 7860class AtomicExprEvaluator : 7861 public ExprEvaluatorBase<AtomicExprEvaluator, bool> { 7862 APValue &Result; 7863public: 7864 AtomicExprEvaluator(EvalInfo &Info, APValue &Result) 7865 : ExprEvaluatorBaseTy(Info), Result(Result) {} 7866 7867 bool Success(const APValue &V, const Expr *E) { 7868 Result = V; 7869 return true; 7870 } 7871 7872 bool ZeroInitialization(const Expr *E) { 7873 ImplicitValueInitExpr VIE( 7874 E->getType()->castAs<AtomicType>()->getValueType()); 7875 return Evaluate(Result, Info, &VIE); 7876 } 7877 7878 bool VisitCastExpr(const CastExpr *E) { 7879 switch (E->getCastKind()) { 7880 default: 7881 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7882 case CK_NonAtomicToAtomic: 7883 return Evaluate(Result, Info, E->getSubExpr()); 7884 } 7885 } 7886}; 7887} // end anonymous namespace 7888 7889static bool EvaluateAtomic(const Expr *E, APValue &Result, EvalInfo &Info) { 7890 assert(E->isRValue() && E->getType()->isAtomicType()); 7891 return AtomicExprEvaluator(Info, Result).Visit(E); 7892} 7893 7894//===----------------------------------------------------------------------===// 7895// Void expression evaluation, primarily for a cast to void on the LHS of a 7896// comma operator 7897//===----------------------------------------------------------------------===// 7898 7899namespace { 7900class VoidExprEvaluator 7901 : public ExprEvaluatorBase<VoidExprEvaluator, bool> { 7902public: 7903 VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {} 7904 7905 bool Success(const APValue &V, const Expr *e) { return true; } 7906 7907 bool VisitCastExpr(const CastExpr *E) { 7908 switch (E->getCastKind()) { 7909 default: 7910 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7911 case CK_ToVoid: 7912 VisitIgnoredValue(E->getSubExpr()); 7913 return true; 7914 } 7915 } 7916}; 7917} // end anonymous namespace 7918 7919static bool EvaluateVoid(const Expr *E, EvalInfo &Info) { 7920 assert(E->isRValue() && E->getType()->isVoidType()); 7921 return VoidExprEvaluator(Info).Visit(E); 7922} 7923 7924//===----------------------------------------------------------------------===// 7925// Top level Expr::EvaluateAsRValue method. 7926//===----------------------------------------------------------------------===// 7927 7928static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) { 7929 // In C, function designators are not lvalues, but we evaluate them as if they 7930 // are. 7931 QualType T = E->getType(); 7932 if (E->isGLValue() || T->isFunctionType()) { 7933 LValue LV; 7934 if (!EvaluateLValue(E, LV, Info)) 7935 return false; 7936 LV.moveInto(Result); 7937 } else if (T->isVectorType()) { 7938 if (!EvaluateVector(E, Result, Info)) 7939 return false; 7940 } else if (T->isIntegralOrEnumerationType()) { 7941 if (!IntExprEvaluator(Info, Result).Visit(E)) 7942 return false; 7943 } else if (T->hasPointerRepresentation()) { 7944 LValue LV; 7945 if (!EvaluatePointer(E, LV, Info)) 7946 return false; 7947 LV.moveInto(Result); 7948 } else if (T->isRealFloatingType()) { 7949 llvm::APFloat F(0.0); 7950 if (!EvaluateFloat(E, F, Info)) 7951 return false; 7952 Result = APValue(F); 7953 } else if (T->isAnyComplexType()) { 7954 ComplexValue C; 7955 if (!EvaluateComplex(E, C, Info)) 7956 return false; 7957 C.moveInto(Result); 7958 } else if (T->isMemberPointerType()) { 7959 MemberPtr P; 7960 if (!EvaluateMemberPointer(E, P, Info)) 7961 return false; 7962 P.moveInto(Result); 7963 return true; 7964 } else if (T->isArrayType()) { 7965 LValue LV; 7966 LV.set(E, Info.CurrentCall->Index); 7967 APValue &Value = Info.CurrentCall->createTemporary(E, false); 7968 if (!EvaluateArray(E, LV, Value, Info)) 7969 return false; 7970 Result = Value; 7971 } else if (T->isRecordType()) { 7972 LValue LV; 7973 LV.set(E, Info.CurrentCall->Index); 7974 APValue &Value = Info.CurrentCall->createTemporary(E, false); 7975 if (!EvaluateRecord(E, LV, Value, Info)) 7976 return false; 7977 Result = Value; 7978 } else if (T->isVoidType()) { 7979 if (!Info.getLangOpts().CPlusPlus11) 7980 Info.CCEDiag(E, diag::note_constexpr_nonliteral) 7981 << E->getType(); 7982 if (!EvaluateVoid(E, Info)) 7983 return false; 7984 } else if (T->isAtomicType()) { 7985 if (!EvaluateAtomic(E, Result, Info)) 7986 return false; 7987 } else if (Info.getLangOpts().CPlusPlus11) { 7988 Info.Diag(E, diag::note_constexpr_nonliteral) << E->getType(); 7989 return false; 7990 } else { 7991 Info.Diag(E, diag::note_invalid_subexpr_in_const_expr); 7992 return false; 7993 } 7994 7995 return true; 7996} 7997 7998/// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some 7999/// cases, the in-place evaluation is essential, since later initializers for 8000/// an object can indirectly refer to subobjects which were initialized earlier. 8001static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This, 8002 const Expr *E, bool AllowNonLiteralTypes) { 8003 if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This)) 8004 return false; 8005 8006 if (E->isRValue()) { 8007 // Evaluate arrays and record types in-place, so that later initializers can 8008 // refer to earlier-initialized members of the object. 8009 if (E->getType()->isArrayType()) 8010 return EvaluateArray(E, This, Result, Info); 8011 else if (E->getType()->isRecordType()) 8012 return EvaluateRecord(E, This, Result, Info); 8013 } 8014 8015 // For any other type, in-place evaluation is unimportant. 8016 return Evaluate(Result, Info, E); 8017} 8018 8019/// EvaluateAsRValue - Try to evaluate this expression, performing an implicit 8020/// lvalue-to-rvalue cast if it is an lvalue. 8021static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) { 8022 if (!CheckLiteralType(Info, E)) 8023 return false; 8024 8025 if (!::Evaluate(Result, Info, E)) 8026 return false; 8027 8028 if (E->isGLValue()) { 8029 LValue LV; 8030 LV.setFrom(Info.Ctx, Result); 8031 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result)) 8032 return false; 8033 } 8034 8035 // Check this core constant expression is a constant expression. 8036 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result); 8037} 8038 8039static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result, 8040 const ASTContext &Ctx, bool &IsConst) { 8041 // Fast-path evaluations of integer literals, since we sometimes see files 8042 // containing vast quantities of these. 8043 if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) { 8044 Result.Val = APValue(APSInt(L->getValue(), 8045 L->getType()->isUnsignedIntegerType())); 8046 IsConst = true; 8047 return true; 8048 } 8049 8050 // FIXME: Evaluating values of large array and record types can cause 8051 // performance problems. Only do so in C++11 for now. 8052 if (Exp->isRValue() && (Exp->getType()->isArrayType() || 8053 Exp->getType()->isRecordType()) && 8054 !Ctx.getLangOpts().CPlusPlus11) { 8055 IsConst = false; 8056 return true; 8057 } 8058 return false; 8059} 8060 8061 8062/// EvaluateAsRValue - Return true if this is a constant which we can fold using 8063/// any crazy technique (that has nothing to do with language standards) that 8064/// we want to. If this function returns true, it returns the folded constant 8065/// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion 8066/// will be applied to the result. 8067bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx) const { 8068 bool IsConst; 8069 if (FastEvaluateAsRValue(this, Result, Ctx, IsConst)) 8070 return IsConst; 8071 8072 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); 8073 return ::EvaluateAsRValue(Info, this, Result.Val); 8074} 8075 8076bool Expr::EvaluateAsBooleanCondition(bool &Result, 8077 const ASTContext &Ctx) const { 8078 EvalResult Scratch; 8079 return EvaluateAsRValue(Scratch, Ctx) && 8080 HandleConversionToBool(Scratch.Val, Result); 8081} 8082 8083bool Expr::EvaluateAsInt(APSInt &Result, const ASTContext &Ctx, 8084 SideEffectsKind AllowSideEffects) const { 8085 if (!getType()->isIntegralOrEnumerationType()) 8086 return false; 8087 8088 EvalResult ExprResult; 8089 if (!EvaluateAsRValue(ExprResult, Ctx) || !ExprResult.Val.isInt() || 8090 (!AllowSideEffects && ExprResult.HasSideEffects)) 8091 return false; 8092 8093 Result = ExprResult.Val.getInt(); 8094 return true; 8095} 8096 8097bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx) const { 8098 EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold); 8099 8100 LValue LV; 8101 if (!EvaluateLValue(this, LV, Info) || Result.HasSideEffects || 8102 !CheckLValueConstantExpression(Info, getExprLoc(), 8103 Ctx.getLValueReferenceType(getType()), LV)) 8104 return false; 8105 8106 LV.moveInto(Result.Val); 8107 return true; 8108} 8109 8110bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx, 8111 const VarDecl *VD, 8112 SmallVectorImpl<PartialDiagnosticAt> &Notes) const { 8113 // FIXME: Evaluating initializers for large array and record types can cause 8114 // performance problems. Only do so in C++11 for now. 8115 if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) && 8116 !Ctx.getLangOpts().CPlusPlus11) 8117 return false; 8118 8119 Expr::EvalStatus EStatus; 8120 EStatus.Diag = &Notes; 8121 8122 EvalInfo InitInfo(Ctx, EStatus, EvalInfo::EM_ConstantFold); 8123 InitInfo.setEvaluatingDecl(VD, Value); 8124 8125 LValue LVal; 8126 LVal.set(VD); 8127 8128 // C++11 [basic.start.init]p2: 8129 // Variables with static storage duration or thread storage duration shall be 8130 // zero-initialized before any other initialization takes place. 8131 // This behavior is not present in C. 8132 if (Ctx.getLangOpts().CPlusPlus && !VD->hasLocalStorage() && 8133 !VD->getType()->isReferenceType()) { 8134 ImplicitValueInitExpr VIE(VD->getType()); 8135 if (!EvaluateInPlace(Value, InitInfo, LVal, &VIE, 8136 /*AllowNonLiteralTypes=*/true)) 8137 return false; 8138 } 8139 8140 if (!EvaluateInPlace(Value, InitInfo, LVal, this, 8141 /*AllowNonLiteralTypes=*/true) || 8142 EStatus.HasSideEffects) 8143 return false; 8144 8145 return CheckConstantExpression(InitInfo, VD->getLocation(), VD->getType(), 8146 Value); 8147} 8148 8149/// isEvaluatable - Call EvaluateAsRValue to see if this expression can be 8150/// constant folded, but discard the result. 8151bool Expr::isEvaluatable(const ASTContext &Ctx) const { 8152 EvalResult Result; 8153 return EvaluateAsRValue(Result, Ctx) && !Result.HasSideEffects; 8154} 8155 8156APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx, 8157 SmallVectorImpl<PartialDiagnosticAt> *Diag) const { 8158 EvalResult EvalResult; 8159 EvalResult.Diag = Diag; 8160 bool Result = EvaluateAsRValue(EvalResult, Ctx); 8161 (void)Result; 8162 assert(Result && "Could not evaluate expression"); 8163 assert(EvalResult.Val.isInt() && "Expression did not evaluate to integer"); 8164 8165 return EvalResult.Val.getInt(); 8166} 8167 8168void Expr::EvaluateForOverflow(const ASTContext &Ctx) const { 8169 bool IsConst; 8170 EvalResult EvalResult; 8171 if (!FastEvaluateAsRValue(this, EvalResult, Ctx, IsConst)) { 8172 EvalInfo Info(Ctx, EvalResult, EvalInfo::EM_EvaluateForOverflow); 8173 (void)::EvaluateAsRValue(Info, this, EvalResult.Val); 8174 } 8175} 8176 8177bool Expr::EvalResult::isGlobalLValue() const { 8178 assert(Val.isLValue()); 8179 return IsGlobalLValue(Val.getLValueBase()); 8180} 8181 8182 8183/// isIntegerConstantExpr - this recursive routine will test if an expression is 8184/// an integer constant expression. 8185 8186/// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero, 8187/// comma, etc 8188 8189// CheckICE - This function does the fundamental ICE checking: the returned 8190// ICEDiag contains an ICEKind indicating whether the expression is an ICE, 8191// and a (possibly null) SourceLocation indicating the location of the problem. 8192// 8193// Note that to reduce code duplication, this helper does no evaluation 8194// itself; the caller checks whether the expression is evaluatable, and 8195// in the rare cases where CheckICE actually cares about the evaluated 8196// value, it calls into Evalute. 8197 8198namespace { 8199 8200enum ICEKind { 8201 /// This expression is an ICE. 8202 IK_ICE, 8203 /// This expression is not an ICE, but if it isn't evaluated, it's 8204 /// a legal subexpression for an ICE. This return value is used to handle 8205 /// the comma operator in C99 mode, and non-constant subexpressions. 8206 IK_ICEIfUnevaluated, 8207 /// This expression is not an ICE, and is not a legal subexpression for one. 8208 IK_NotICE 8209}; 8210 8211struct ICEDiag { 8212 ICEKind Kind; 8213 SourceLocation Loc; 8214 8215 ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {} 8216}; 8217 8218} 8219 8220static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); } 8221 8222static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; } 8223 8224static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) { 8225 Expr::EvalResult EVResult; 8226 if (!E->EvaluateAsRValue(EVResult, Ctx) || EVResult.HasSideEffects || 8227 !EVResult.Val.isInt()) 8228 return ICEDiag(IK_NotICE, E->getLocStart()); 8229 8230 return NoDiag(); 8231} 8232 8233static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) { 8234 assert(!E->isValueDependent() && "Should not see value dependent exprs!"); 8235 if (!E->getType()->isIntegralOrEnumerationType()) 8236 return ICEDiag(IK_NotICE, E->getLocStart()); 8237 8238 switch (E->getStmtClass()) { 8239#define ABSTRACT_STMT(Node) 8240#define STMT(Node, Base) case Expr::Node##Class: 8241#define EXPR(Node, Base) 8242#include "clang/AST/StmtNodes.inc" 8243 case Expr::PredefinedExprClass: 8244 case Expr::FloatingLiteralClass: 8245 case Expr::ImaginaryLiteralClass: 8246 case Expr::StringLiteralClass: 8247 case Expr::ArraySubscriptExprClass: 8248 case Expr::MemberExprClass: 8249 case Expr::CompoundAssignOperatorClass: 8250 case Expr::CompoundLiteralExprClass: 8251 case Expr::ExtVectorElementExprClass: 8252 case Expr::DesignatedInitExprClass: 8253 case Expr::ImplicitValueInitExprClass: 8254 case Expr::ParenListExprClass: 8255 case Expr::VAArgExprClass: 8256 case Expr::AddrLabelExprClass: 8257 case Expr::StmtExprClass: 8258 case Expr::CXXMemberCallExprClass: 8259 case Expr::CUDAKernelCallExprClass: 8260 case Expr::CXXDynamicCastExprClass: 8261 case Expr::CXXTypeidExprClass: 8262 case Expr::CXXUuidofExprClass: 8263 case Expr::MSPropertyRefExprClass: 8264 case Expr::CXXNullPtrLiteralExprClass: 8265 case Expr::UserDefinedLiteralClass: 8266 case Expr::CXXThisExprClass: 8267 case Expr::CXXThrowExprClass: 8268 case Expr::CXXNewExprClass: 8269 case Expr::CXXDeleteExprClass: 8270 case Expr::CXXPseudoDestructorExprClass: 8271 case Expr::UnresolvedLookupExprClass: 8272 case Expr::DependentScopeDeclRefExprClass: 8273 case Expr::CXXConstructExprClass: 8274 case Expr::CXXStdInitializerListExprClass: 8275 case Expr::CXXBindTemporaryExprClass: 8276 case Expr::ExprWithCleanupsClass: 8277 case Expr::CXXTemporaryObjectExprClass: 8278 case Expr::CXXUnresolvedConstructExprClass: 8279 case Expr::CXXDependentScopeMemberExprClass: 8280 case Expr::UnresolvedMemberExprClass: 8281 case Expr::ObjCStringLiteralClass: 8282 case Expr::ObjCBoxedExprClass: 8283 case Expr::ObjCArrayLiteralClass: 8284 case Expr::ObjCDictionaryLiteralClass: 8285 case Expr::ObjCEncodeExprClass: 8286 case Expr::ObjCMessageExprClass: 8287 case Expr::ObjCSelectorExprClass: 8288 case Expr::ObjCProtocolExprClass: 8289 case Expr::ObjCIvarRefExprClass: 8290 case Expr::ObjCPropertyRefExprClass: 8291 case Expr::ObjCSubscriptRefExprClass: 8292 case Expr::ObjCIsaExprClass: 8293 case Expr::ShuffleVectorExprClass: 8294 case Expr::ConvertVectorExprClass: 8295 case Expr::BlockExprClass: 8296 case Expr::NoStmtClass: 8297 case Expr::OpaqueValueExprClass: 8298 case Expr::PackExpansionExprClass: 8299 case Expr::SubstNonTypeTemplateParmPackExprClass: 8300 case Expr::FunctionParmPackExprClass: 8301 case Expr::AsTypeExprClass: 8302 case Expr::ObjCIndirectCopyRestoreExprClass: 8303 case Expr::MaterializeTemporaryExprClass: 8304 case Expr::PseudoObjectExprClass: 8305 case Expr::AtomicExprClass: 8306 case Expr::InitListExprClass: 8307 case Expr::LambdaExprClass: 8308 return ICEDiag(IK_NotICE, E->getLocStart()); 8309 8310 case Expr::SizeOfPackExprClass: 8311 case Expr::GNUNullExprClass: 8312 // GCC considers the GNU __null value to be an integral constant expression. 8313 return NoDiag(); 8314 8315 case Expr::SubstNonTypeTemplateParmExprClass: 8316 return 8317 CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx); 8318 8319 case Expr::ParenExprClass: 8320 return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx); 8321 case Expr::GenericSelectionExprClass: 8322 return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx); 8323 case Expr::IntegerLiteralClass: 8324 case Expr::CharacterLiteralClass: 8325 case Expr::ObjCBoolLiteralExprClass: 8326 case Expr::CXXBoolLiteralExprClass: 8327 case Expr::CXXScalarValueInitExprClass: 8328 case Expr::UnaryTypeTraitExprClass: 8329 case Expr::BinaryTypeTraitExprClass: 8330 case Expr::TypeTraitExprClass: 8331 case Expr::ArrayTypeTraitExprClass: 8332 case Expr::ExpressionTraitExprClass: 8333 case Expr::CXXNoexceptExprClass: 8334 return NoDiag(); 8335 case Expr::CallExprClass: 8336 case Expr::CXXOperatorCallExprClass: { 8337 // C99 6.6/3 allows function calls within unevaluated subexpressions of 8338 // constant expressions, but they can never be ICEs because an ICE cannot 8339 // contain an operand of (pointer to) function type. 8340 const CallExpr *CE = cast<CallExpr>(E); 8341 if (CE->isBuiltinCall()) 8342 return CheckEvalInICE(E, Ctx); 8343 return ICEDiag(IK_NotICE, E->getLocStart()); 8344 } 8345 case Expr::DeclRefExprClass: { 8346 if (isa<EnumConstantDecl>(cast<DeclRefExpr>(E)->getDecl())) 8347 return NoDiag(); 8348 const ValueDecl *D = dyn_cast<ValueDecl>(cast<DeclRefExpr>(E)->getDecl()); 8349 if (Ctx.getLangOpts().CPlusPlus && 8350 D && IsConstNonVolatile(D->getType())) { 8351 // Parameter variables are never constants. Without this check, 8352 // getAnyInitializer() can find a default argument, which leads 8353 // to chaos. 8354 if (isa<ParmVarDecl>(D)) 8355 return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); 8356 8357 // C++ 7.1.5.1p2 8358 // A variable of non-volatile const-qualified integral or enumeration 8359 // type initialized by an ICE can be used in ICEs. 8360 if (const VarDecl *Dcl = dyn_cast<VarDecl>(D)) { 8361 if (!Dcl->getType()->isIntegralOrEnumerationType()) 8362 return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); 8363 8364 const VarDecl *VD; 8365 // Look for a declaration of this variable that has an initializer, and 8366 // check whether it is an ICE. 8367 if (Dcl->getAnyInitializer(VD) && VD->checkInitIsICE()) 8368 return NoDiag(); 8369 else 8370 return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); 8371 } 8372 } 8373 return ICEDiag(IK_NotICE, E->getLocStart()); 8374 } 8375 case Expr::UnaryOperatorClass: { 8376 const UnaryOperator *Exp = cast<UnaryOperator>(E); 8377 switch (Exp->getOpcode()) { 8378 case UO_PostInc: 8379 case UO_PostDec: 8380 case UO_PreInc: 8381 case UO_PreDec: 8382 case UO_AddrOf: 8383 case UO_Deref: 8384 // C99 6.6/3 allows increment and decrement within unevaluated 8385 // subexpressions of constant expressions, but they can never be ICEs 8386 // because an ICE cannot contain an lvalue operand. 8387 return ICEDiag(IK_NotICE, E->getLocStart()); 8388 case UO_Extension: 8389 case UO_LNot: 8390 case UO_Plus: 8391 case UO_Minus: 8392 case UO_Not: 8393 case UO_Real: 8394 case UO_Imag: 8395 return CheckICE(Exp->getSubExpr(), Ctx); 8396 } 8397 8398 // OffsetOf falls through here. 8399 } 8400 case Expr::OffsetOfExprClass: { 8401 // Note that per C99, offsetof must be an ICE. And AFAIK, using 8402 // EvaluateAsRValue matches the proposed gcc behavior for cases like 8403 // "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect 8404 // compliance: we should warn earlier for offsetof expressions with 8405 // array subscripts that aren't ICEs, and if the array subscripts 8406 // are ICEs, the value of the offsetof must be an integer constant. 8407 return CheckEvalInICE(E, Ctx); 8408 } 8409 case Expr::UnaryExprOrTypeTraitExprClass: { 8410 const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E); 8411 if ((Exp->getKind() == UETT_SizeOf) && 8412 Exp->getTypeOfArgument()->isVariableArrayType()) 8413 return ICEDiag(IK_NotICE, E->getLocStart()); 8414 return NoDiag(); 8415 } 8416 case Expr::BinaryOperatorClass: { 8417 const BinaryOperator *Exp = cast<BinaryOperator>(E); 8418 switch (Exp->getOpcode()) { 8419 case BO_PtrMemD: 8420 case BO_PtrMemI: 8421 case BO_Assign: 8422 case BO_MulAssign: 8423 case BO_DivAssign: 8424 case BO_RemAssign: 8425 case BO_AddAssign: 8426 case BO_SubAssign: 8427 case BO_ShlAssign: 8428 case BO_ShrAssign: 8429 case BO_AndAssign: 8430 case BO_XorAssign: 8431 case BO_OrAssign: 8432 // C99 6.6/3 allows assignments within unevaluated subexpressions of 8433 // constant expressions, but they can never be ICEs because an ICE cannot 8434 // contain an lvalue operand. 8435 return ICEDiag(IK_NotICE, E->getLocStart()); 8436 8437 case BO_Mul: 8438 case BO_Div: 8439 case BO_Rem: 8440 case BO_Add: 8441 case BO_Sub: 8442 case BO_Shl: 8443 case BO_Shr: 8444 case BO_LT: 8445 case BO_GT: 8446 case BO_LE: 8447 case BO_GE: 8448 case BO_EQ: 8449 case BO_NE: 8450 case BO_And: 8451 case BO_Xor: 8452 case BO_Or: 8453 case BO_Comma: { 8454 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); 8455 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); 8456 if (Exp->getOpcode() == BO_Div || 8457 Exp->getOpcode() == BO_Rem) { 8458 // EvaluateAsRValue gives an error for undefined Div/Rem, so make sure 8459 // we don't evaluate one. 8460 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) { 8461 llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx); 8462 if (REval == 0) 8463 return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); 8464 if (REval.isSigned() && REval.isAllOnesValue()) { 8465 llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx); 8466 if (LEval.isMinSignedValue()) 8467 return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); 8468 } 8469 } 8470 } 8471 if (Exp->getOpcode() == BO_Comma) { 8472 if (Ctx.getLangOpts().C99) { 8473 // C99 6.6p3 introduces a strange edge case: comma can be in an ICE 8474 // if it isn't evaluated. 8475 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) 8476 return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart()); 8477 } else { 8478 // In both C89 and C++, commas in ICEs are illegal. 8479 return ICEDiag(IK_NotICE, E->getLocStart()); 8480 } 8481 } 8482 return Worst(LHSResult, RHSResult); 8483 } 8484 case BO_LAnd: 8485 case BO_LOr: { 8486 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); 8487 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); 8488 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) { 8489 // Rare case where the RHS has a comma "side-effect"; we need 8490 // to actually check the condition to see whether the side 8491 // with the comma is evaluated. 8492 if ((Exp->getOpcode() == BO_LAnd) != 8493 (Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0)) 8494 return RHSResult; 8495 return NoDiag(); 8496 } 8497 8498 return Worst(LHSResult, RHSResult); 8499 } 8500 } 8501 } 8502 case Expr::ImplicitCastExprClass: 8503 case Expr::CStyleCastExprClass: 8504 case Expr::CXXFunctionalCastExprClass: 8505 case Expr::CXXStaticCastExprClass: 8506 case Expr::CXXReinterpretCastExprClass: 8507 case Expr::CXXConstCastExprClass: 8508 case Expr::ObjCBridgedCastExprClass: { 8509 const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr(); 8510 if (isa<ExplicitCastExpr>(E)) { 8511 if (const FloatingLiteral *FL 8512 = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) { 8513 unsigned DestWidth = Ctx.getIntWidth(E->getType()); 8514 bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType(); 8515 APSInt IgnoredVal(DestWidth, !DestSigned); 8516 bool Ignored; 8517 // If the value does not fit in the destination type, the behavior is 8518 // undefined, so we are not required to treat it as a constant 8519 // expression. 8520 if (FL->getValue().convertToInteger(IgnoredVal, 8521 llvm::APFloat::rmTowardZero, 8522 &Ignored) & APFloat::opInvalidOp) 8523 return ICEDiag(IK_NotICE, E->getLocStart()); 8524 return NoDiag(); 8525 } 8526 } 8527 switch (cast<CastExpr>(E)->getCastKind()) { 8528 case CK_LValueToRValue: 8529 case CK_AtomicToNonAtomic: 8530 case CK_NonAtomicToAtomic: 8531 case CK_NoOp: 8532 case CK_IntegralToBoolean: 8533 case CK_IntegralCast: 8534 return CheckICE(SubExpr, Ctx); 8535 default: 8536 return ICEDiag(IK_NotICE, E->getLocStart()); 8537 } 8538 } 8539 case Expr::BinaryConditionalOperatorClass: { 8540 const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E); 8541 ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx); 8542 if (CommonResult.Kind == IK_NotICE) return CommonResult; 8543 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); 8544 if (FalseResult.Kind == IK_NotICE) return FalseResult; 8545 if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult; 8546 if (FalseResult.Kind == IK_ICEIfUnevaluated && 8547 Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag(); 8548 return FalseResult; 8549 } 8550 case Expr::ConditionalOperatorClass: { 8551 const ConditionalOperator *Exp = cast<ConditionalOperator>(E); 8552 // If the condition (ignoring parens) is a __builtin_constant_p call, 8553 // then only the true side is actually considered in an integer constant 8554 // expression, and it is fully evaluated. This is an important GNU 8555 // extension. See GCC PR38377 for discussion. 8556 if (const CallExpr *CallCE 8557 = dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts())) 8558 if (CallCE->isBuiltinCall() == Builtin::BI__builtin_constant_p) 8559 return CheckEvalInICE(E, Ctx); 8560 ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx); 8561 if (CondResult.Kind == IK_NotICE) 8562 return CondResult; 8563 8564 ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx); 8565 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); 8566 8567 if (TrueResult.Kind == IK_NotICE) 8568 return TrueResult; 8569 if (FalseResult.Kind == IK_NotICE) 8570 return FalseResult; 8571 if (CondResult.Kind == IK_ICEIfUnevaluated) 8572 return CondResult; 8573 if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE) 8574 return NoDiag(); 8575 // Rare case where the diagnostics depend on which side is evaluated 8576 // Note that if we get here, CondResult is 0, and at least one of 8577 // TrueResult and FalseResult is non-zero. 8578 if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0) 8579 return FalseResult; 8580 return TrueResult; 8581 } 8582 case Expr::CXXDefaultArgExprClass: 8583 return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx); 8584 case Expr::CXXDefaultInitExprClass: 8585 return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx); 8586 case Expr::ChooseExprClass: { 8587 return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx); 8588 } 8589 } 8590 8591 llvm_unreachable("Invalid StmtClass!"); 8592} 8593 8594/// Evaluate an expression as a C++11 integral constant expression. 8595static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx, 8596 const Expr *E, 8597 llvm::APSInt *Value, 8598 SourceLocation *Loc) { 8599 if (!E->getType()->isIntegralOrEnumerationType()) { 8600 if (Loc) *Loc = E->getExprLoc(); 8601 return false; 8602 } 8603 8604 APValue Result; 8605 if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc)) 8606 return false; 8607 8608 assert(Result.isInt() && "pointer cast to int is not an ICE"); 8609 if (Value) *Value = Result.getInt(); 8610 return true; 8611} 8612 8613bool Expr::isIntegerConstantExpr(const ASTContext &Ctx, 8614 SourceLocation *Loc) const { 8615 if (Ctx.getLangOpts().CPlusPlus11) 8616 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, 0, Loc); 8617 8618 ICEDiag D = CheckICE(this, Ctx); 8619 if (D.Kind != IK_ICE) { 8620 if (Loc) *Loc = D.Loc; 8621 return false; 8622 } 8623 return true; 8624} 8625 8626bool Expr::isIntegerConstantExpr(llvm::APSInt &Value, const ASTContext &Ctx, 8627 SourceLocation *Loc, bool isEvaluated) const { 8628 if (Ctx.getLangOpts().CPlusPlus11) 8629 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc); 8630 8631 if (!isIntegerConstantExpr(Ctx, Loc)) 8632 return false; 8633 if (!EvaluateAsInt(Value, Ctx)) 8634 llvm_unreachable("ICE cannot be evaluated!"); 8635 return true; 8636} 8637 8638bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const { 8639 return CheckICE(this, Ctx).Kind == IK_ICE; 8640} 8641 8642bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result, 8643 SourceLocation *Loc) const { 8644 // We support this checking in C++98 mode in order to diagnose compatibility 8645 // issues. 8646 assert(Ctx.getLangOpts().CPlusPlus); 8647 8648 // Build evaluation settings. 8649 Expr::EvalStatus Status; 8650 SmallVector<PartialDiagnosticAt, 8> Diags; 8651 Status.Diag = &Diags; 8652 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression); 8653 8654 APValue Scratch; 8655 bool IsConstExpr = ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch); 8656 8657 if (!Diags.empty()) { 8658 IsConstExpr = false; 8659 if (Loc) *Loc = Diags[0].first; 8660 } else if (!IsConstExpr) { 8661 // FIXME: This shouldn't happen. 8662 if (Loc) *Loc = getExprLoc(); 8663 } 8664 8665 return IsConstExpr; 8666} 8667 8668bool Expr::isPotentialConstantExpr(const FunctionDecl *FD, 8669 SmallVectorImpl< 8670 PartialDiagnosticAt> &Diags) { 8671 // FIXME: It would be useful to check constexpr function templates, but at the 8672 // moment the constant expression evaluator cannot cope with the non-rigorous 8673 // ASTs which we build for dependent expressions. 8674 if (FD->isDependentContext()) 8675 return true; 8676 8677 Expr::EvalStatus Status; 8678 Status.Diag = &Diags; 8679 8680 EvalInfo Info(FD->getASTContext(), Status, 8681 EvalInfo::EM_PotentialConstantExpression); 8682 8683 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); 8684 const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : 0; 8685 8686 // Fabricate an arbitrary expression on the stack and pretend that it 8687 // is a temporary being used as the 'this' pointer. 8688 LValue This; 8689 ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy); 8690 This.set(&VIE, Info.CurrentCall->Index); 8691 8692 ArrayRef<const Expr*> Args; 8693 8694 SourceLocation Loc = FD->getLocation(); 8695 8696 APValue Scratch; 8697 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) { 8698 // Evaluate the call as a constant initializer, to allow the construction 8699 // of objects of non-literal types. 8700 Info.setEvaluatingDecl(This.getLValueBase(), Scratch); 8701 HandleConstructorCall(Loc, This, Args, CD, Info, Scratch); 8702 } else 8703 HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : 0, 8704 Args, FD->getBody(), Info, Scratch); 8705 8706 return Diags.empty(); 8707} 8708