SemaStmtAsm.cpp revision 252723
1//===--- SemaStmtAsm.cpp - Semantic Analysis for Asm Statements -----------===// 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 semantic analysis for inline asm statements. 11// 12//===----------------------------------------------------------------------===// 13 14#include "clang/Sema/SemaInternal.h" 15#include "clang/AST/RecordLayout.h" 16#include "clang/AST/TypeLoc.h" 17#include "clang/Basic/TargetInfo.h" 18#include "clang/Lex/Preprocessor.h" 19#include "clang/Sema/Initialization.h" 20#include "clang/Sema/Lookup.h" 21#include "clang/Sema/Scope.h" 22#include "clang/Sema/ScopeInfo.h" 23#include "llvm/ADT/ArrayRef.h" 24#include "llvm/ADT/BitVector.h" 25using namespace clang; 26using namespace sema; 27 28/// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently 29/// ignore "noop" casts in places where an lvalue is required by an inline asm. 30/// We emulate this behavior when -fheinous-gnu-extensions is specified, but 31/// provide a strong guidance to not use it. 32/// 33/// This method checks to see if the argument is an acceptable l-value and 34/// returns false if it is a case we can handle. 35static bool CheckAsmLValue(const Expr *E, Sema &S) { 36 // Type dependent expressions will be checked during instantiation. 37 if (E->isTypeDependent()) 38 return false; 39 40 if (E->isLValue()) 41 return false; // Cool, this is an lvalue. 42 43 // Okay, this is not an lvalue, but perhaps it is the result of a cast that we 44 // are supposed to allow. 45 const Expr *E2 = E->IgnoreParenNoopCasts(S.Context); 46 if (E != E2 && E2->isLValue()) { 47 if (!S.getLangOpts().HeinousExtensions) 48 S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue) 49 << E->getSourceRange(); 50 else 51 S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue) 52 << E->getSourceRange(); 53 // Accept, even if we emitted an error diagnostic. 54 return false; 55 } 56 57 // None of the above, just randomly invalid non-lvalue. 58 return true; 59} 60 61/// isOperandMentioned - Return true if the specified operand # is mentioned 62/// anywhere in the decomposed asm string. 63static bool isOperandMentioned(unsigned OpNo, 64 ArrayRef<GCCAsmStmt::AsmStringPiece> AsmStrPieces) { 65 for (unsigned p = 0, e = AsmStrPieces.size(); p != e; ++p) { 66 const GCCAsmStmt::AsmStringPiece &Piece = AsmStrPieces[p]; 67 if (!Piece.isOperand()) continue; 68 69 // If this is a reference to the input and if the input was the smaller 70 // one, then we have to reject this asm. 71 if (Piece.getOperandNo() == OpNo) 72 return true; 73 } 74 return false; 75} 76 77StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple, 78 bool IsVolatile, unsigned NumOutputs, 79 unsigned NumInputs, IdentifierInfo **Names, 80 MultiExprArg constraints, MultiExprArg exprs, 81 Expr *asmString, MultiExprArg clobbers, 82 SourceLocation RParenLoc) { 83 unsigned NumClobbers = clobbers.size(); 84 StringLiteral **Constraints = 85 reinterpret_cast<StringLiteral**>(constraints.data()); 86 Expr **Exprs = exprs.data(); 87 StringLiteral *AsmString = cast<StringLiteral>(asmString); 88 StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.data()); 89 90 SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos; 91 92 // The parser verifies that there is a string literal here. 93 if (!AsmString->isAscii()) 94 return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character) 95 << AsmString->getSourceRange()); 96 97 for (unsigned i = 0; i != NumOutputs; i++) { 98 StringLiteral *Literal = Constraints[i]; 99 if (!Literal->isAscii()) 100 return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character) 101 << Literal->getSourceRange()); 102 103 StringRef OutputName; 104 if (Names[i]) 105 OutputName = Names[i]->getName(); 106 107 TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName); 108 if (!Context.getTargetInfo().validateOutputConstraint(Info)) 109 return StmtError(Diag(Literal->getLocStart(), 110 diag::err_asm_invalid_output_constraint) 111 << Info.getConstraintStr()); 112 113 // Check that the output exprs are valid lvalues. 114 Expr *OutputExpr = Exprs[i]; 115 if (CheckAsmLValue(OutputExpr, *this)) 116 return StmtError(Diag(OutputExpr->getLocStart(), 117 diag::err_asm_invalid_lvalue_in_output) 118 << OutputExpr->getSourceRange()); 119 120 if (RequireCompleteType(OutputExpr->getLocStart(), Exprs[i]->getType(), 121 diag::err_dereference_incomplete_type)) 122 return StmtError(); 123 124 OutputConstraintInfos.push_back(Info); 125 } 126 127 SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos; 128 129 for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) { 130 StringLiteral *Literal = Constraints[i]; 131 if (!Literal->isAscii()) 132 return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character) 133 << Literal->getSourceRange()); 134 135 StringRef InputName; 136 if (Names[i]) 137 InputName = Names[i]->getName(); 138 139 TargetInfo::ConstraintInfo Info(Literal->getString(), InputName); 140 if (!Context.getTargetInfo().validateInputConstraint(OutputConstraintInfos.data(), 141 NumOutputs, Info)) { 142 return StmtError(Diag(Literal->getLocStart(), 143 diag::err_asm_invalid_input_constraint) 144 << Info.getConstraintStr()); 145 } 146 147 Expr *InputExpr = Exprs[i]; 148 149 // Only allow void types for memory constraints. 150 if (Info.allowsMemory() && !Info.allowsRegister()) { 151 if (CheckAsmLValue(InputExpr, *this)) 152 return StmtError(Diag(InputExpr->getLocStart(), 153 diag::err_asm_invalid_lvalue_in_input) 154 << Info.getConstraintStr() 155 << InputExpr->getSourceRange()); 156 } 157 158 if (Info.allowsRegister()) { 159 if (InputExpr->getType()->isVoidType()) { 160 return StmtError(Diag(InputExpr->getLocStart(), 161 diag::err_asm_invalid_type_in_input) 162 << InputExpr->getType() << Info.getConstraintStr() 163 << InputExpr->getSourceRange()); 164 } 165 } 166 167 ExprResult Result = DefaultFunctionArrayLvalueConversion(Exprs[i]); 168 if (Result.isInvalid()) 169 return StmtError(); 170 171 Exprs[i] = Result.take(); 172 InputConstraintInfos.push_back(Info); 173 174 const Type *Ty = Exprs[i]->getType().getTypePtr(); 175 if (Ty->isDependentType()) 176 continue; 177 178 if (!Ty->isVoidType() || !Info.allowsMemory()) 179 if (RequireCompleteType(InputExpr->getLocStart(), Exprs[i]->getType(), 180 diag::err_dereference_incomplete_type)) 181 return StmtError(); 182 183 unsigned Size = Context.getTypeSize(Ty); 184 if (!Context.getTargetInfo().validateInputSize(Literal->getString(), 185 Size)) 186 return StmtError(Diag(InputExpr->getLocStart(), 187 diag::err_asm_invalid_input_size) 188 << Info.getConstraintStr()); 189 } 190 191 // Check that the clobbers are valid. 192 for (unsigned i = 0; i != NumClobbers; i++) { 193 StringLiteral *Literal = Clobbers[i]; 194 if (!Literal->isAscii()) 195 return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character) 196 << Literal->getSourceRange()); 197 198 StringRef Clobber = Literal->getString(); 199 200 if (!Context.getTargetInfo().isValidClobber(Clobber)) 201 return StmtError(Diag(Literal->getLocStart(), 202 diag::err_asm_unknown_register_name) << Clobber); 203 } 204 205 GCCAsmStmt *NS = 206 new (Context) GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs, 207 NumInputs, Names, Constraints, Exprs, AsmString, 208 NumClobbers, Clobbers, RParenLoc); 209 // Validate the asm string, ensuring it makes sense given the operands we 210 // have. 211 SmallVector<GCCAsmStmt::AsmStringPiece, 8> Pieces; 212 unsigned DiagOffs; 213 if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) { 214 Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID) 215 << AsmString->getSourceRange(); 216 return StmtError(); 217 } 218 219 // Validate constraints and modifiers. 220 for (unsigned i = 0, e = Pieces.size(); i != e; ++i) { 221 GCCAsmStmt::AsmStringPiece &Piece = Pieces[i]; 222 if (!Piece.isOperand()) continue; 223 224 // Look for the correct constraint index. 225 unsigned Idx = 0; 226 unsigned ConstraintIdx = 0; 227 for (unsigned i = 0, e = NS->getNumOutputs(); i != e; ++i, ++ConstraintIdx) { 228 TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i]; 229 if (Idx == Piece.getOperandNo()) 230 break; 231 ++Idx; 232 233 if (Info.isReadWrite()) { 234 if (Idx == Piece.getOperandNo()) 235 break; 236 ++Idx; 237 } 238 } 239 240 for (unsigned i = 0, e = NS->getNumInputs(); i != e; ++i, ++ConstraintIdx) { 241 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; 242 if (Idx == Piece.getOperandNo()) 243 break; 244 ++Idx; 245 246 if (Info.isReadWrite()) { 247 if (Idx == Piece.getOperandNo()) 248 break; 249 ++Idx; 250 } 251 } 252 253 // Now that we have the right indexes go ahead and check. 254 StringLiteral *Literal = Constraints[ConstraintIdx]; 255 const Type *Ty = Exprs[ConstraintIdx]->getType().getTypePtr(); 256 if (Ty->isDependentType() || Ty->isIncompleteType()) 257 continue; 258 259 unsigned Size = Context.getTypeSize(Ty); 260 if (!Context.getTargetInfo() 261 .validateConstraintModifier(Literal->getString(), Piece.getModifier(), 262 Size)) 263 Diag(Exprs[ConstraintIdx]->getLocStart(), 264 diag::warn_asm_mismatched_size_modifier); 265 } 266 267 // Validate tied input operands for type mismatches. 268 for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) { 269 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; 270 271 // If this is a tied constraint, verify that the output and input have 272 // either exactly the same type, or that they are int/ptr operands with the 273 // same size (int/long, int*/long, are ok etc). 274 if (!Info.hasTiedOperand()) continue; 275 276 unsigned TiedTo = Info.getTiedOperand(); 277 unsigned InputOpNo = i+NumOutputs; 278 Expr *OutputExpr = Exprs[TiedTo]; 279 Expr *InputExpr = Exprs[InputOpNo]; 280 281 if (OutputExpr->isTypeDependent() || InputExpr->isTypeDependent()) 282 continue; 283 284 QualType InTy = InputExpr->getType(); 285 QualType OutTy = OutputExpr->getType(); 286 if (Context.hasSameType(InTy, OutTy)) 287 continue; // All types can be tied to themselves. 288 289 // Decide if the input and output are in the same domain (integer/ptr or 290 // floating point. 291 enum AsmDomain { 292 AD_Int, AD_FP, AD_Other 293 } InputDomain, OutputDomain; 294 295 if (InTy->isIntegerType() || InTy->isPointerType()) 296 InputDomain = AD_Int; 297 else if (InTy->isRealFloatingType()) 298 InputDomain = AD_FP; 299 else 300 InputDomain = AD_Other; 301 302 if (OutTy->isIntegerType() || OutTy->isPointerType()) 303 OutputDomain = AD_Int; 304 else if (OutTy->isRealFloatingType()) 305 OutputDomain = AD_FP; 306 else 307 OutputDomain = AD_Other; 308 309 // They are ok if they are the same size and in the same domain. This 310 // allows tying things like: 311 // void* to int* 312 // void* to int if they are the same size. 313 // double to long double if they are the same size. 314 // 315 uint64_t OutSize = Context.getTypeSize(OutTy); 316 uint64_t InSize = Context.getTypeSize(InTy); 317 if (OutSize == InSize && InputDomain == OutputDomain && 318 InputDomain != AD_Other) 319 continue; 320 321 // If the smaller input/output operand is not mentioned in the asm string, 322 // then we can promote the smaller one to a larger input and the asm string 323 // won't notice. 324 bool SmallerValueMentioned = false; 325 326 // If this is a reference to the input and if the input was the smaller 327 // one, then we have to reject this asm. 328 if (isOperandMentioned(InputOpNo, Pieces)) { 329 // This is a use in the asm string of the smaller operand. Since we 330 // codegen this by promoting to a wider value, the asm will get printed 331 // "wrong". 332 SmallerValueMentioned |= InSize < OutSize; 333 } 334 if (isOperandMentioned(TiedTo, Pieces)) { 335 // If this is a reference to the output, and if the output is the larger 336 // value, then it's ok because we'll promote the input to the larger type. 337 SmallerValueMentioned |= OutSize < InSize; 338 } 339 340 // If the smaller value wasn't mentioned in the asm string, and if the 341 // output was a register, just extend the shorter one to the size of the 342 // larger one. 343 if (!SmallerValueMentioned && InputDomain != AD_Other && 344 OutputConstraintInfos[TiedTo].allowsRegister()) 345 continue; 346 347 // Either both of the operands were mentioned or the smaller one was 348 // mentioned. One more special case that we'll allow: if the tied input is 349 // integer, unmentioned, and is a constant, then we'll allow truncating it 350 // down to the size of the destination. 351 if (InputDomain == AD_Int && OutputDomain == AD_Int && 352 !isOperandMentioned(InputOpNo, Pieces) && 353 InputExpr->isEvaluatable(Context)) { 354 CastKind castKind = 355 (OutTy->isBooleanType() ? CK_IntegralToBoolean : CK_IntegralCast); 356 InputExpr = ImpCastExprToType(InputExpr, OutTy, castKind).take(); 357 Exprs[InputOpNo] = InputExpr; 358 NS->setInputExpr(i, InputExpr); 359 continue; 360 } 361 362 Diag(InputExpr->getLocStart(), 363 diag::err_asm_tying_incompatible_types) 364 << InTy << OutTy << OutputExpr->getSourceRange() 365 << InputExpr->getSourceRange(); 366 return StmtError(); 367 } 368 369 return Owned(NS); 370} 371 372ExprResult Sema::LookupInlineAsmIdentifier(CXXScopeSpec &SS, 373 SourceLocation TemplateKWLoc, 374 UnqualifiedId &Id, 375 InlineAsmIdentifierInfo &Info, 376 bool IsUnevaluatedContext) { 377 Info.clear(); 378 379 if (IsUnevaluatedContext) 380 PushExpressionEvaluationContext(UnevaluatedAbstract, 381 ReuseLambdaContextDecl); 382 383 ExprResult Result = ActOnIdExpression(getCurScope(), SS, TemplateKWLoc, Id, 384 /*trailing lparen*/ false, 385 /*is & operand*/ false); 386 387 if (IsUnevaluatedContext) 388 PopExpressionEvaluationContext(); 389 390 if (!Result.isUsable()) return Result; 391 392 Result = CheckPlaceholderExpr(Result.take()); 393 if (!Result.isUsable()) return Result; 394 395 QualType T = Result.get()->getType(); 396 397 // For now, reject dependent types. 398 if (T->isDependentType()) { 399 Diag(Id.getLocStart(), diag::err_asm_incomplete_type) << T; 400 return ExprError(); 401 } 402 403 // Any sort of function type is fine. 404 if (T->isFunctionType()) { 405 return Result; 406 } 407 408 // Otherwise, it needs to be a complete type. 409 if (RequireCompleteExprType(Result.get(), diag::err_asm_incomplete_type)) { 410 return ExprError(); 411 } 412 413 // Compute the type size (and array length if applicable?). 414 Info.Type = Info.Size = Context.getTypeSizeInChars(T).getQuantity(); 415 if (T->isArrayType()) { 416 const ArrayType *ATy = Context.getAsArrayType(T); 417 Info.Type = Context.getTypeSizeInChars(ATy->getElementType()).getQuantity(); 418 Info.Length = Info.Size / Info.Type; 419 } 420 421 // We can work with the expression as long as it's not an r-value. 422 if (!Result.get()->isRValue()) 423 Info.IsVarDecl = true; 424 425 return Result; 426} 427 428bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member, 429 unsigned &Offset, SourceLocation AsmLoc) { 430 Offset = 0; 431 LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(), 432 LookupOrdinaryName); 433 434 if (!LookupName(BaseResult, getCurScope())) 435 return true; 436 437 if (!BaseResult.isSingleResult()) 438 return true; 439 440 const RecordType *RT = 0; 441 NamedDecl *FoundDecl = BaseResult.getFoundDecl(); 442 if (VarDecl *VD = dyn_cast<VarDecl>(FoundDecl)) 443 RT = VD->getType()->getAs<RecordType>(); 444 else if (TypedefDecl *TD = dyn_cast<TypedefDecl>(FoundDecl)) 445 RT = TD->getUnderlyingType()->getAs<RecordType>(); 446 if (!RT) 447 return true; 448 449 if (RequireCompleteType(AsmLoc, QualType(RT, 0), 0)) 450 return true; 451 452 LookupResult FieldResult(*this, &Context.Idents.get(Member), SourceLocation(), 453 LookupMemberName); 454 455 if (!LookupQualifiedName(FieldResult, RT->getDecl())) 456 return true; 457 458 // FIXME: Handle IndirectFieldDecl? 459 FieldDecl *FD = dyn_cast<FieldDecl>(FieldResult.getFoundDecl()); 460 if (!FD) 461 return true; 462 463 const ASTRecordLayout &RL = Context.getASTRecordLayout(RT->getDecl()); 464 unsigned i = FD->getFieldIndex(); 465 CharUnits Result = Context.toCharUnitsFromBits(RL.getFieldOffset(i)); 466 Offset = (unsigned)Result.getQuantity(); 467 468 return false; 469} 470 471StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc, 472 ArrayRef<Token> AsmToks, 473 StringRef AsmString, 474 unsigned NumOutputs, unsigned NumInputs, 475 ArrayRef<StringRef> Constraints, 476 ArrayRef<StringRef> Clobbers, 477 ArrayRef<Expr*> Exprs, 478 SourceLocation EndLoc) { 479 bool IsSimple = (NumOutputs != 0 || NumInputs != 0); 480 MSAsmStmt *NS = 481 new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, IsSimple, 482 /*IsVolatile*/ true, AsmToks, NumOutputs, NumInputs, 483 Constraints, Exprs, AsmString, 484 Clobbers, EndLoc); 485 return Owned(NS); 486} 487