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/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"
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());
157 if (Info.allowsRegister()) {
158 if (InputExpr->getType()->isVoidType()) {
159 return StmtError(Diag(InputExpr->getLocStart(),
160 diag::err_asm_invalid_type_in_input)
161 << InputExpr->getType() << Info.getConstraintStr()
162 << InputExpr->getSourceRange());
166 ExprResult Result = DefaultFunctionArrayLvalueConversion(Exprs[i]);
167 if (Result.isInvalid())
170 Exprs[i] = Result.take();
171 InputConstraintInfos.push_back(Info);
173 const Type *Ty = Exprs[i]->getType().getTypePtr();
174 if (Ty->isDependentType())
177 if (!Ty->isVoidType() || !Info.allowsMemory())
178 if (RequireCompleteType(InputExpr->getLocStart(), Exprs[i]->getType(),
179 diag::err_dereference_incomplete_type))
182 unsigned Size = Context.getTypeSize(Ty);
183 if (!Context.getTargetInfo().validateInputSize(Literal->getString(),
185 return StmtError(Diag(InputExpr->getLocStart(),
186 diag::err_asm_invalid_input_size)
187 << Info.getConstraintStr());
190 // Check that the clobbers are valid.
191 for (unsigned i = 0; i != NumClobbers; i++) {
192 StringLiteral *Literal = Clobbers[i];
193 if (!Literal->isAscii())
194 return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
195 << Literal->getSourceRange());
197 StringRef Clobber = Literal->getString();
199 if (!Context.getTargetInfo().isValidClobber(Clobber))
200 return StmtError(Diag(Literal->getLocStart(),
201 diag::err_asm_unknown_register_name) << Clobber);
205 new (Context) GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
206 NumInputs, Names, Constraints, Exprs.data(),
207 AsmString, NumClobbers, Clobbers, RParenLoc);
208 // Validate the asm string, ensuring it makes sense given the operands we
210 SmallVector<GCCAsmStmt::AsmStringPiece, 8> Pieces;
212 if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
213 Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
214 << AsmString->getSourceRange();
218 // Validate constraints and modifiers.
219 for (unsigned i = 0, e = Pieces.size(); i != e; ++i) {
220 GCCAsmStmt::AsmStringPiece &Piece = Pieces[i];
221 if (!Piece.isOperand()) continue;
223 // Look for the correct constraint index.
225 unsigned ConstraintIdx = 0;
226 for (unsigned i = 0, e = NS->getNumOutputs(); i != e; ++i, ++ConstraintIdx) {
227 TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
228 if (Idx == Piece.getOperandNo())
232 if (Info.isReadWrite()) {
233 if (Idx == Piece.getOperandNo())
239 for (unsigned i = 0, e = NS->getNumInputs(); i != e; ++i, ++ConstraintIdx) {
240 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
241 if (Idx == Piece.getOperandNo())
245 if (Info.isReadWrite()) {
246 if (Idx == Piece.getOperandNo())
252 // Now that we have the right indexes go ahead and check.
253 StringLiteral *Literal = Constraints[ConstraintIdx];
254 const Type *Ty = Exprs[ConstraintIdx]->getType().getTypePtr();
255 if (Ty->isDependentType() || Ty->isIncompleteType())
258 unsigned Size = Context.getTypeSize(Ty);
259 if (!Context.getTargetInfo()
260 .validateConstraintModifier(Literal->getString(), Piece.getModifier(),
262 Diag(Exprs[ConstraintIdx]->getLocStart(),
263 diag::warn_asm_mismatched_size_modifier);
266 // Validate tied input operands for type mismatches.
267 for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
268 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
270 // If this is a tied constraint, verify that the output and input have
271 // either exactly the same type, or that they are int/ptr operands with the
272 // same size (int/long, int*/long, are ok etc).
273 if (!Info.hasTiedOperand()) continue;
275 unsigned TiedTo = Info.getTiedOperand();
276 unsigned InputOpNo = i+NumOutputs;
277 Expr *OutputExpr = Exprs[TiedTo];
278 Expr *InputExpr = Exprs[InputOpNo];
280 if (OutputExpr->isTypeDependent() || InputExpr->isTypeDependent())
283 QualType InTy = InputExpr->getType();
284 QualType OutTy = OutputExpr->getType();
285 if (Context.hasSameType(InTy, OutTy))
286 continue; // All types can be tied to themselves.
288 // Decide if the input and output are in the same domain (integer/ptr or
291 AD_Int, AD_FP, AD_Other
292 } InputDomain, OutputDomain;
294 if (InTy->isIntegerType() || InTy->isPointerType())
295 InputDomain = AD_Int;
296 else if (InTy->isRealFloatingType())
299 InputDomain = AD_Other;
301 if (OutTy->isIntegerType() || OutTy->isPointerType())
302 OutputDomain = AD_Int;
303 else if (OutTy->isRealFloatingType())
304 OutputDomain = AD_FP;
306 OutputDomain = AD_Other;
308 // They are ok if they are the same size and in the same domain. This
309 // allows tying things like:
311 // void* to int if they are the same size.
312 // double to long double if they are the same size.
314 uint64_t OutSize = Context.getTypeSize(OutTy);
315 uint64_t InSize = Context.getTypeSize(InTy);
316 if (OutSize == InSize && InputDomain == OutputDomain &&
317 InputDomain != AD_Other)
320 // If the smaller input/output operand is not mentioned in the asm string,
321 // then we can promote the smaller one to a larger input and the asm string
323 bool SmallerValueMentioned = false;
325 // If this is a reference to the input and if the input was the smaller
326 // one, then we have to reject this asm.
327 if (isOperandMentioned(InputOpNo, Pieces)) {
328 // This is a use in the asm string of the smaller operand. Since we
329 // codegen this by promoting to a wider value, the asm will get printed
331 SmallerValueMentioned |= InSize < OutSize;
333 if (isOperandMentioned(TiedTo, Pieces)) {
334 // If this is a reference to the output, and if the output is the larger
335 // value, then it's ok because we'll promote the input to the larger type.
336 SmallerValueMentioned |= OutSize < InSize;
339 // If the smaller value wasn't mentioned in the asm string, and if the
340 // output was a register, just extend the shorter one to the size of the
342 if (!SmallerValueMentioned && InputDomain != AD_Other &&
343 OutputConstraintInfos[TiedTo].allowsRegister())
346 // Either both of the operands were mentioned or the smaller one was
347 // mentioned. One more special case that we'll allow: if the tied input is
348 // integer, unmentioned, and is a constant, then we'll allow truncating it
349 // down to the size of the destination.
350 if (InputDomain == AD_Int && OutputDomain == AD_Int &&
351 !isOperandMentioned(InputOpNo, Pieces) &&
352 InputExpr->isEvaluatable(Context)) {
354 (OutTy->isBooleanType() ? CK_IntegralToBoolean : CK_IntegralCast);
355 InputExpr = ImpCastExprToType(InputExpr, OutTy, castKind).take();
356 Exprs[InputOpNo] = InputExpr;
357 NS->setInputExpr(i, InputExpr);
361 Diag(InputExpr->getLocStart(),
362 diag::err_asm_tying_incompatible_types)
363 << InTy << OutTy << OutputExpr->getSourceRange()
364 << InputExpr->getSourceRange();
371 ExprResult Sema::LookupInlineAsmIdentifier(CXXScopeSpec &SS,
372 SourceLocation TemplateKWLoc,
374 InlineAsmIdentifierInfo &Info,
375 bool IsUnevaluatedContext) {
378 if (IsUnevaluatedContext)
379 PushExpressionEvaluationContext(UnevaluatedAbstract,
380 ReuseLambdaContextDecl);
382 ExprResult Result = ActOnIdExpression(getCurScope(), SS, TemplateKWLoc, Id,
383 /*trailing lparen*/ false,
384 /*is & operand*/ false,
385 /*CorrectionCandidateCallback=*/0,
386 /*IsInlineAsmIdentifier=*/ true);
388 if (IsUnevaluatedContext)
389 PopExpressionEvaluationContext();
391 if (!Result.isUsable()) return Result;
393 Result = CheckPlaceholderExpr(Result.take());
394 if (!Result.isUsable()) return Result;
396 QualType T = Result.get()->getType();
398 // For now, reject dependent types.
399 if (T->isDependentType()) {
400 Diag(Id.getLocStart(), diag::err_asm_incomplete_type) << T;
404 // Any sort of function type is fine.
405 if (T->isFunctionType()) {
409 // Otherwise, it needs to be a complete type.
410 if (RequireCompleteExprType(Result.get(), diag::err_asm_incomplete_type)) {
414 // Compute the type size (and array length if applicable?).
415 Info.Type = Info.Size = Context.getTypeSizeInChars(T).getQuantity();
416 if (T->isArrayType()) {
417 const ArrayType *ATy = Context.getAsArrayType(T);
418 Info.Type = Context.getTypeSizeInChars(ATy->getElementType()).getQuantity();
419 Info.Length = Info.Size / Info.Type;
422 // We can work with the expression as long as it's not an r-value.
423 if (!Result.get()->isRValue())
424 Info.IsVarDecl = true;
429 bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member,
430 unsigned &Offset, SourceLocation AsmLoc) {
432 LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(),
435 if (!LookupName(BaseResult, getCurScope()))
438 if (!BaseResult.isSingleResult())
441 const RecordType *RT = 0;
442 NamedDecl *FoundDecl = BaseResult.getFoundDecl();
443 if (VarDecl *VD = dyn_cast<VarDecl>(FoundDecl))
444 RT = VD->getType()->getAs<RecordType>();
445 else if (TypedefDecl *TD = dyn_cast<TypedefDecl>(FoundDecl))
446 RT = TD->getUnderlyingType()->getAs<RecordType>();
450 if (RequireCompleteType(AsmLoc, QualType(RT, 0), 0))
453 LookupResult FieldResult(*this, &Context.Idents.get(Member), SourceLocation(),
456 if (!LookupQualifiedName(FieldResult, RT->getDecl()))
459 // FIXME: Handle IndirectFieldDecl?
460 FieldDecl *FD = dyn_cast<FieldDecl>(FieldResult.getFoundDecl());
464 const ASTRecordLayout &RL = Context.getASTRecordLayout(RT->getDecl());
465 unsigned i = FD->getFieldIndex();
466 CharUnits Result = Context.toCharUnitsFromBits(RL.getFieldOffset(i));
467 Offset = (unsigned)Result.getQuantity();
472 StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
473 ArrayRef<Token> AsmToks,
475 unsigned NumOutputs, unsigned NumInputs,
476 ArrayRef<StringRef> Constraints,
477 ArrayRef<StringRef> Clobbers,
478 ArrayRef<Expr*> Exprs,
479 SourceLocation EndLoc) {
480 bool IsSimple = (NumOutputs != 0 || NumInputs != 0);
482 new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, IsSimple,
483 /*IsVolatile*/ true, AsmToks, NumOutputs, NumInputs,
484 Constraints, Exprs, AsmString,