1 //===--- SemaStmtAsm.cpp - Semantic Analysis for Asm Statements -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements semantic analysis for inline asm statements.
12 //===----------------------------------------------------------------------===//
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/Sema/Initialization.h"
19 #include "clang/Sema/Lookup.h"
20 #include "clang/Sema/Scope.h"
21 #include "clang/Sema/ScopeInfo.h"
22 #include "llvm/ADT/ArrayRef.h"
23 #include "llvm/ADT/BitVector.h"
24 #include "llvm/MC/MCParser/MCAsmParser.h"
25 using namespace clang;
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.
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.
35 static bool CheckAsmLValue(const Expr *E, Sema &S) {
36 // Type dependent expressions will be checked during instantiation.
37 if (E->isTypeDependent())
41 return false; // Cool, this is an lvalue.
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();
51 S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
52 << E->getSourceRange();
53 // Accept, even if we emitted an error diagnostic.
57 // None of the above, just randomly invalid non-lvalue.
61 /// isOperandMentioned - Return true if the specified operand # is mentioned
62 /// anywhere in the decomposed asm string.
63 static 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;
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)
77 StmtResult 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 StringLiteral *AsmString = cast<StringLiteral>(asmString);
87 StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.data());
89 SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
91 // The parser verifies that there is a string literal here.
92 if (!AsmString->isAscii())
93 return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
94 << AsmString->getSourceRange());
96 for (unsigned i = 0; i != NumOutputs; i++) {
97 StringLiteral *Literal = Constraints[i];
98 if (!Literal->isAscii())
99 return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
100 << Literal->getSourceRange());
102 StringRef OutputName;
104 OutputName = Names[i]->getName();
106 TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
107 if (!Context.getTargetInfo().validateOutputConstraint(Info))
108 return StmtError(Diag(Literal->getLocStart(),
109 diag::err_asm_invalid_output_constraint)
110 << Info.getConstraintStr());
112 // Check that the output exprs are valid lvalues.
113 Expr *OutputExpr = Exprs[i];
114 if (CheckAsmLValue(OutputExpr, *this))
115 return StmtError(Diag(OutputExpr->getLocStart(),
116 diag::err_asm_invalid_lvalue_in_output)
117 << OutputExpr->getSourceRange());
119 if (RequireCompleteType(OutputExpr->getLocStart(), Exprs[i]->getType(),
120 diag::err_dereference_incomplete_type))
123 OutputConstraintInfos.push_back(Info);
126 SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
128 for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
129 StringLiteral *Literal = Constraints[i];
130 if (!Literal->isAscii())
131 return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
132 << Literal->getSourceRange());
136 InputName = Names[i]->getName();
138 TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
139 if (!Context.getTargetInfo().validateInputConstraint(OutputConstraintInfos.data(),
141 return StmtError(Diag(Literal->getLocStart(),
142 diag::err_asm_invalid_input_constraint)
143 << Info.getConstraintStr());
146 Expr *InputExpr = Exprs[i];
148 // Only allow void types for memory constraints.
149 if (Info.allowsMemory() && !Info.allowsRegister()) {
150 if (CheckAsmLValue(InputExpr, *this))
151 return StmtError(Diag(InputExpr->getLocStart(),
152 diag::err_asm_invalid_lvalue_in_input)
153 << Info.getConstraintStr()
154 << InputExpr->getSourceRange());
156 ExprResult Result = DefaultFunctionArrayLvalueConversion(Exprs[i]);
157 if (Result.isInvalid())
160 Exprs[i] = Result.get();
163 if (Info.allowsRegister()) {
164 if (InputExpr->getType()->isVoidType()) {
165 return StmtError(Diag(InputExpr->getLocStart(),
166 diag::err_asm_invalid_type_in_input)
167 << InputExpr->getType() << Info.getConstraintStr()
168 << InputExpr->getSourceRange());
172 InputConstraintInfos.push_back(Info);
174 const Type *Ty = Exprs[i]->getType().getTypePtr();
175 if (Ty->isDependentType())
178 if (!Ty->isVoidType() || !Info.allowsMemory())
179 if (RequireCompleteType(InputExpr->getLocStart(), Exprs[i]->getType(),
180 diag::err_dereference_incomplete_type))
183 unsigned Size = Context.getTypeSize(Ty);
184 if (!Context.getTargetInfo().validateInputSize(Literal->getString(),
186 return StmtError(Diag(InputExpr->getLocStart(),
187 diag::err_asm_invalid_input_size)
188 << Info.getConstraintStr());
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());
198 StringRef Clobber = Literal->getString();
200 if (!Context.getTargetInfo().isValidClobber(Clobber))
201 return StmtError(Diag(Literal->getLocStart(),
202 diag::err_asm_unknown_register_name) << Clobber);
206 new (Context) GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
207 NumInputs, Names, Constraints, Exprs.data(),
208 AsmString, NumClobbers, Clobbers, RParenLoc);
209 // Validate the asm string, ensuring it makes sense given the operands we
211 SmallVector<GCCAsmStmt::AsmStringPiece, 8> Pieces;
213 if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
214 Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
215 << AsmString->getSourceRange();
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;
224 // Look for the correct constraint index.
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())
233 if (Info.isReadWrite()) {
234 if (Idx == Piece.getOperandNo())
240 for (unsigned i = 0, e = NS->getNumInputs(); i != e; ++i, ++ConstraintIdx) {
241 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
242 if (Idx == Piece.getOperandNo())
246 if (Info.isReadWrite()) {
247 if (Idx == Piece.getOperandNo())
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())
259 unsigned Size = Context.getTypeSize(Ty);
260 if (!Context.getTargetInfo()
261 .validateConstraintModifier(Literal->getString(), Piece.getModifier(),
263 Diag(Exprs[ConstraintIdx]->getLocStart(),
264 diag::warn_asm_mismatched_size_modifier);
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];
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;
276 unsigned TiedTo = Info.getTiedOperand();
277 unsigned InputOpNo = i+NumOutputs;
278 Expr *OutputExpr = Exprs[TiedTo];
279 Expr *InputExpr = Exprs[InputOpNo];
281 if (OutputExpr->isTypeDependent() || InputExpr->isTypeDependent())
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.
289 // Decide if the input and output are in the same domain (integer/ptr or
292 AD_Int, AD_FP, AD_Other
293 } InputDomain, OutputDomain;
295 if (InTy->isIntegerType() || InTy->isPointerType())
296 InputDomain = AD_Int;
297 else if (InTy->isRealFloatingType())
300 InputDomain = AD_Other;
302 if (OutTy->isIntegerType() || OutTy->isPointerType())
303 OutputDomain = AD_Int;
304 else if (OutTy->isRealFloatingType())
305 OutputDomain = AD_FP;
307 OutputDomain = AD_Other;
309 // They are ok if they are the same size and in the same domain. This
310 // allows tying things like:
312 // void* to int if they are the same size.
313 // double to long double if they are the same size.
315 uint64_t OutSize = Context.getTypeSize(OutTy);
316 uint64_t InSize = Context.getTypeSize(InTy);
317 if (OutSize == InSize && InputDomain == OutputDomain &&
318 InputDomain != AD_Other)
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
324 bool SmallerValueMentioned = false;
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
332 SmallerValueMentioned |= InSize < OutSize;
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;
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
343 if (!SmallerValueMentioned && InputDomain != AD_Other &&
344 OutputConstraintInfos[TiedTo].allowsRegister())
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)) {
355 (OutTy->isBooleanType() ? CK_IntegralToBoolean : CK_IntegralCast);
356 InputExpr = ImpCastExprToType(InputExpr, OutTy, castKind).get();
357 Exprs[InputOpNo] = InputExpr;
358 NS->setInputExpr(i, InputExpr);
362 Diag(InputExpr->getLocStart(),
363 diag::err_asm_tying_incompatible_types)
364 << InTy << OutTy << OutputExpr->getSourceRange()
365 << InputExpr->getSourceRange();
372 ExprResult Sema::LookupInlineAsmIdentifier(CXXScopeSpec &SS,
373 SourceLocation TemplateKWLoc,
375 llvm::InlineAsmIdentifierInfo &Info,
376 bool IsUnevaluatedContext) {
379 if (IsUnevaluatedContext)
380 PushExpressionEvaluationContext(UnevaluatedAbstract,
381 ReuseLambdaContextDecl);
383 ExprResult Result = ActOnIdExpression(getCurScope(), SS, TemplateKWLoc, Id,
384 /*trailing lparen*/ false,
385 /*is & operand*/ false,
386 /*CorrectionCandidateCallback=*/nullptr,
387 /*IsInlineAsmIdentifier=*/ true);
389 if (IsUnevaluatedContext)
390 PopExpressionEvaluationContext();
392 if (!Result.isUsable()) return Result;
394 Result = CheckPlaceholderExpr(Result.get());
395 if (!Result.isUsable()) return Result;
397 QualType T = Result.get()->getType();
399 // For now, reject dependent types.
400 if (T->isDependentType()) {
401 Diag(Id.getLocStart(), diag::err_asm_incomplete_type) << T;
405 // Any sort of function type is fine.
406 if (T->isFunctionType()) {
410 // Otherwise, it needs to be a complete type.
411 if (RequireCompleteExprType(Result.get(), diag::err_asm_incomplete_type)) {
415 // Compute the type size (and array length if applicable?).
416 Info.Type = Info.Size = Context.getTypeSizeInChars(T).getQuantity();
417 if (T->isArrayType()) {
418 const ArrayType *ATy = Context.getAsArrayType(T);
419 Info.Type = Context.getTypeSizeInChars(ATy->getElementType()).getQuantity();
420 Info.Length = Info.Size / Info.Type;
423 // We can work with the expression as long as it's not an r-value.
424 if (!Result.get()->isRValue())
425 Info.IsVarDecl = true;
430 bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member,
431 unsigned &Offset, SourceLocation AsmLoc) {
433 LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(),
436 if (!LookupName(BaseResult, getCurScope()))
439 if (!BaseResult.isSingleResult())
442 const RecordType *RT = nullptr;
443 NamedDecl *FoundDecl = BaseResult.getFoundDecl();
444 if (VarDecl *VD = dyn_cast<VarDecl>(FoundDecl))
445 RT = VD->getType()->getAs<RecordType>();
446 else if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(FoundDecl))
447 RT = TD->getUnderlyingType()->getAs<RecordType>();
448 else if (TypeDecl *TD = dyn_cast<TypeDecl>(FoundDecl))
449 RT = TD->getTypeForDecl()->getAs<RecordType>();
453 if (RequireCompleteType(AsmLoc, QualType(RT, 0), 0))
456 LookupResult FieldResult(*this, &Context.Idents.get(Member), SourceLocation(),
459 if (!LookupQualifiedName(FieldResult, RT->getDecl()))
462 // FIXME: Handle IndirectFieldDecl?
463 FieldDecl *FD = dyn_cast<FieldDecl>(FieldResult.getFoundDecl());
467 const ASTRecordLayout &RL = Context.getASTRecordLayout(RT->getDecl());
468 unsigned i = FD->getFieldIndex();
469 CharUnits Result = Context.toCharUnitsFromBits(RL.getFieldOffset(i));
470 Offset = (unsigned)Result.getQuantity();
475 StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
476 ArrayRef<Token> AsmToks,
478 unsigned NumOutputs, unsigned NumInputs,
479 ArrayRef<StringRef> Constraints,
480 ArrayRef<StringRef> Clobbers,
481 ArrayRef<Expr*> Exprs,
482 SourceLocation EndLoc) {
483 bool IsSimple = (NumOutputs != 0 || NumInputs != 0);
485 new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, IsSimple,
486 /*IsVolatile*/ true, AsmToks, NumOutputs, NumInputs,
487 Constraints, Exprs, AsmString,