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 #include "llvm/MC/MCParser/MCAsmParser.h"
26 using namespace clang;
29 /// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently
30 /// ignore "noop" casts in places where an lvalue is required by an inline asm.
31 /// We emulate this behavior when -fheinous-gnu-extensions is specified, but
32 /// provide a strong guidance to not use it.
34 /// This method checks to see if the argument is an acceptable l-value and
35 /// returns false if it is a case we can handle.
36 static bool CheckAsmLValue(const Expr *E, Sema &S) {
37 // Type dependent expressions will be checked during instantiation.
38 if (E->isTypeDependent())
42 return false; // Cool, this is an lvalue.
44 // Okay, this is not an lvalue, but perhaps it is the result of a cast that we
45 // are supposed to allow.
46 const Expr *E2 = E->IgnoreParenNoopCasts(S.Context);
47 if (E != E2 && E2->isLValue()) {
48 if (!S.getLangOpts().HeinousExtensions)
49 S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue)
50 << E->getSourceRange();
52 S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
53 << E->getSourceRange();
54 // Accept, even if we emitted an error diagnostic.
58 // None of the above, just randomly invalid non-lvalue.
62 /// isOperandMentioned - Return true if the specified operand # is mentioned
63 /// anywhere in the decomposed asm string.
64 static bool isOperandMentioned(unsigned OpNo,
65 ArrayRef<GCCAsmStmt::AsmStringPiece> AsmStrPieces) {
66 for (unsigned p = 0, e = AsmStrPieces.size(); p != e; ++p) {
67 const GCCAsmStmt::AsmStringPiece &Piece = AsmStrPieces[p];
68 if (!Piece.isOperand()) continue;
70 // If this is a reference to the input and if the input was the smaller
71 // one, then we have to reject this asm.
72 if (Piece.getOperandNo() == OpNo)
78 static bool CheckNakedParmReference(Expr *E, Sema &S) {
79 FunctionDecl *Func = dyn_cast<FunctionDecl>(S.CurContext);
82 if (!Func->hasAttr<NakedAttr>())
85 SmallVector<Expr*, 4> WorkList;
86 WorkList.push_back(E);
87 while (WorkList.size()) {
88 Expr *E = WorkList.pop_back_val();
89 if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
90 if (isa<ParmVarDecl>(DRE->getDecl())) {
91 S.Diag(DRE->getLocStart(), diag::err_asm_naked_parm_ref);
92 S.Diag(Func->getAttr<NakedAttr>()->getLocation(), diag::note_attribute);
96 for (Stmt *Child : E->children()) {
97 if (Expr *E = dyn_cast_or_null<Expr>(Child))
98 WorkList.push_back(E);
104 StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple,
105 bool IsVolatile, unsigned NumOutputs,
106 unsigned NumInputs, IdentifierInfo **Names,
107 MultiExprArg constraints, MultiExprArg Exprs,
108 Expr *asmString, MultiExprArg clobbers,
109 SourceLocation RParenLoc) {
110 unsigned NumClobbers = clobbers.size();
111 StringLiteral **Constraints =
112 reinterpret_cast<StringLiteral**>(constraints.data());
113 StringLiteral *AsmString = cast<StringLiteral>(asmString);
114 StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.data());
116 SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
118 // The parser verifies that there is a string literal here.
119 assert(AsmString->isAscii());
121 for (unsigned i = 0; i != NumOutputs; i++) {
122 StringLiteral *Literal = Constraints[i];
123 assert(Literal->isAscii());
125 StringRef OutputName;
127 OutputName = Names[i]->getName();
129 TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName);
130 if (!Context.getTargetInfo().validateOutputConstraint(Info))
131 return StmtError(Diag(Literal->getLocStart(),
132 diag::err_asm_invalid_output_constraint)
133 << Info.getConstraintStr());
135 ExprResult ER = CheckPlaceholderExpr(Exprs[i]);
140 // Check that the output exprs are valid lvalues.
141 Expr *OutputExpr = Exprs[i];
143 // Referring to parameters is not allowed in naked functions.
144 if (CheckNakedParmReference(OutputExpr, *this))
147 OutputConstraintInfos.push_back(Info);
149 // If this is dependent, just continue.
150 if (OutputExpr->isTypeDependent())
153 Expr::isModifiableLvalueResult IsLV =
154 OutputExpr->isModifiableLvalue(Context, /*Loc=*/nullptr);
156 case Expr::MLV_Valid:
157 // Cool, this is an lvalue.
159 case Expr::MLV_ArrayType:
162 case Expr::MLV_LValueCast: {
163 const Expr *LVal = OutputExpr->IgnoreParenNoopCasts(Context);
164 if (!getLangOpts().HeinousExtensions) {
165 Diag(LVal->getLocStart(), diag::err_invalid_asm_cast_lvalue)
166 << OutputExpr->getSourceRange();
168 Diag(LVal->getLocStart(), diag::warn_invalid_asm_cast_lvalue)
169 << OutputExpr->getSourceRange();
171 // Accept, even if we emitted an error diagnostic.
174 case Expr::MLV_IncompleteType:
175 case Expr::MLV_IncompleteVoidType:
176 if (RequireCompleteType(OutputExpr->getLocStart(), Exprs[i]->getType(),
177 diag::err_dereference_incomplete_type))
180 return StmtError(Diag(OutputExpr->getLocStart(),
181 diag::err_asm_invalid_lvalue_in_output)
182 << OutputExpr->getSourceRange());
185 unsigned Size = Context.getTypeSize(OutputExpr->getType());
186 if (!Context.getTargetInfo().validateOutputSize(Literal->getString(),
188 return StmtError(Diag(OutputExpr->getLocStart(),
189 diag::err_asm_invalid_output_size)
190 << Info.getConstraintStr());
193 SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
195 for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
196 StringLiteral *Literal = Constraints[i];
197 assert(Literal->isAscii());
201 InputName = Names[i]->getName();
203 TargetInfo::ConstraintInfo Info(Literal->getString(), InputName);
204 if (!Context.getTargetInfo().validateInputConstraint(OutputConstraintInfos.data(),
206 return StmtError(Diag(Literal->getLocStart(),
207 diag::err_asm_invalid_input_constraint)
208 << Info.getConstraintStr());
211 ExprResult ER = CheckPlaceholderExpr(Exprs[i]);
216 Expr *InputExpr = Exprs[i];
218 // Referring to parameters is not allowed in naked functions.
219 if (CheckNakedParmReference(InputExpr, *this))
222 // Only allow void types for memory constraints.
223 if (Info.allowsMemory() && !Info.allowsRegister()) {
224 if (CheckAsmLValue(InputExpr, *this))
225 return StmtError(Diag(InputExpr->getLocStart(),
226 diag::err_asm_invalid_lvalue_in_input)
227 << Info.getConstraintStr()
228 << InputExpr->getSourceRange());
229 } else if (Info.requiresImmediateConstant() && !Info.allowsRegister()) {
231 if (!InputExpr->EvaluateAsInt(Result, Context))
233 Diag(InputExpr->getLocStart(), diag::err_asm_invalid_type_in_input)
234 << InputExpr->getType() << Info.getConstraintStr()
235 << InputExpr->getSourceRange());
236 if (Result.slt(Info.getImmConstantMin()) ||
237 Result.sgt(Info.getImmConstantMax()))
238 return StmtError(Diag(InputExpr->getLocStart(),
239 diag::err_invalid_asm_value_for_constraint)
240 << Result.toString(10) << Info.getConstraintStr()
241 << InputExpr->getSourceRange());
244 ExprResult Result = DefaultFunctionArrayLvalueConversion(Exprs[i]);
245 if (Result.isInvalid())
248 Exprs[i] = Result.get();
251 if (Info.allowsRegister()) {
252 if (InputExpr->getType()->isVoidType()) {
253 return StmtError(Diag(InputExpr->getLocStart(),
254 diag::err_asm_invalid_type_in_input)
255 << InputExpr->getType() << Info.getConstraintStr()
256 << InputExpr->getSourceRange());
260 InputConstraintInfos.push_back(Info);
262 const Type *Ty = Exprs[i]->getType().getTypePtr();
263 if (Ty->isDependentType())
266 if (!Ty->isVoidType() || !Info.allowsMemory())
267 if (RequireCompleteType(InputExpr->getLocStart(), Exprs[i]->getType(),
268 diag::err_dereference_incomplete_type))
271 unsigned Size = Context.getTypeSize(Ty);
272 if (!Context.getTargetInfo().validateInputSize(Literal->getString(),
274 return StmtError(Diag(InputExpr->getLocStart(),
275 diag::err_asm_invalid_input_size)
276 << Info.getConstraintStr());
279 // Check that the clobbers are valid.
280 for (unsigned i = 0; i != NumClobbers; i++) {
281 StringLiteral *Literal = Clobbers[i];
282 assert(Literal->isAscii());
284 StringRef Clobber = Literal->getString();
286 if (!Context.getTargetInfo().isValidClobber(Clobber))
287 return StmtError(Diag(Literal->getLocStart(),
288 diag::err_asm_unknown_register_name) << Clobber);
292 new (Context) GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs,
293 NumInputs, Names, Constraints, Exprs.data(),
294 AsmString, NumClobbers, Clobbers, RParenLoc);
295 // Validate the asm string, ensuring it makes sense given the operands we
297 SmallVector<GCCAsmStmt::AsmStringPiece, 8> Pieces;
299 if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) {
300 Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID)
301 << AsmString->getSourceRange();
305 // Validate constraints and modifiers.
306 for (unsigned i = 0, e = Pieces.size(); i != e; ++i) {
307 GCCAsmStmt::AsmStringPiece &Piece = Pieces[i];
308 if (!Piece.isOperand()) continue;
310 // Look for the correct constraint index.
312 unsigned ConstraintIdx = 0;
313 for (unsigned i = 0, e = NS->getNumOutputs(); i != e; ++i, ++ConstraintIdx) {
314 TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
315 if (Idx == Piece.getOperandNo())
319 if (Info.isReadWrite()) {
320 if (Idx == Piece.getOperandNo())
326 for (unsigned i = 0, e = NS->getNumInputs(); i != e; ++i, ++ConstraintIdx) {
327 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
328 if (Idx == Piece.getOperandNo())
332 if (Info.isReadWrite()) {
333 if (Idx == Piece.getOperandNo())
339 // Now that we have the right indexes go ahead and check.
340 StringLiteral *Literal = Constraints[ConstraintIdx];
341 const Type *Ty = Exprs[ConstraintIdx]->getType().getTypePtr();
342 if (Ty->isDependentType() || Ty->isIncompleteType())
345 unsigned Size = Context.getTypeSize(Ty);
346 std::string SuggestedModifier;
347 if (!Context.getTargetInfo().validateConstraintModifier(
348 Literal->getString(), Piece.getModifier(), Size,
349 SuggestedModifier)) {
350 Diag(Exprs[ConstraintIdx]->getLocStart(),
351 diag::warn_asm_mismatched_size_modifier);
353 if (!SuggestedModifier.empty()) {
354 auto B = Diag(Piece.getRange().getBegin(),
355 diag::note_asm_missing_constraint_modifier)
356 << SuggestedModifier;
357 SuggestedModifier = "%" + SuggestedModifier + Piece.getString();
358 B.AddFixItHint(FixItHint::CreateReplacement(Piece.getRange(),
364 // Validate tied input operands for type mismatches.
365 unsigned NumAlternatives = ~0U;
366 for (unsigned i = 0, e = OutputConstraintInfos.size(); i != e; ++i) {
367 TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
368 StringRef ConstraintStr = Info.getConstraintStr();
369 unsigned AltCount = ConstraintStr.count(',') + 1;
370 if (NumAlternatives == ~0U)
371 NumAlternatives = AltCount;
372 else if (NumAlternatives != AltCount)
373 return StmtError(Diag(NS->getOutputExpr(i)->getLocStart(),
374 diag::err_asm_unexpected_constraint_alternatives)
375 << NumAlternatives << AltCount);
377 for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
378 TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
379 StringRef ConstraintStr = Info.getConstraintStr();
380 unsigned AltCount = ConstraintStr.count(',') + 1;
381 if (NumAlternatives == ~0U)
382 NumAlternatives = AltCount;
383 else if (NumAlternatives != AltCount)
384 return StmtError(Diag(NS->getInputExpr(i)->getLocStart(),
385 diag::err_asm_unexpected_constraint_alternatives)
386 << NumAlternatives << AltCount);
388 // If this is a tied constraint, verify that the output and input have
389 // either exactly the same type, or that they are int/ptr operands with the
390 // same size (int/long, int*/long, are ok etc).
391 if (!Info.hasTiedOperand()) continue;
393 unsigned TiedTo = Info.getTiedOperand();
394 unsigned InputOpNo = i+NumOutputs;
395 Expr *OutputExpr = Exprs[TiedTo];
396 Expr *InputExpr = Exprs[InputOpNo];
398 if (OutputExpr->isTypeDependent() || InputExpr->isTypeDependent())
401 QualType InTy = InputExpr->getType();
402 QualType OutTy = OutputExpr->getType();
403 if (Context.hasSameType(InTy, OutTy))
404 continue; // All types can be tied to themselves.
406 // Decide if the input and output are in the same domain (integer/ptr or
409 AD_Int, AD_FP, AD_Other
410 } InputDomain, OutputDomain;
412 if (InTy->isIntegerType() || InTy->isPointerType())
413 InputDomain = AD_Int;
414 else if (InTy->isRealFloatingType())
417 InputDomain = AD_Other;
419 if (OutTy->isIntegerType() || OutTy->isPointerType())
420 OutputDomain = AD_Int;
421 else if (OutTy->isRealFloatingType())
422 OutputDomain = AD_FP;
424 OutputDomain = AD_Other;
426 // They are ok if they are the same size and in the same domain. This
427 // allows tying things like:
429 // void* to int if they are the same size.
430 // double to long double if they are the same size.
432 uint64_t OutSize = Context.getTypeSize(OutTy);
433 uint64_t InSize = Context.getTypeSize(InTy);
434 if (OutSize == InSize && InputDomain == OutputDomain &&
435 InputDomain != AD_Other)
438 // If the smaller input/output operand is not mentioned in the asm string,
439 // then we can promote the smaller one to a larger input and the asm string
441 bool SmallerValueMentioned = false;
443 // If this is a reference to the input and if the input was the smaller
444 // one, then we have to reject this asm.
445 if (isOperandMentioned(InputOpNo, Pieces)) {
446 // This is a use in the asm string of the smaller operand. Since we
447 // codegen this by promoting to a wider value, the asm will get printed
449 SmallerValueMentioned |= InSize < OutSize;
451 if (isOperandMentioned(TiedTo, Pieces)) {
452 // If this is a reference to the output, and if the output is the larger
453 // value, then it's ok because we'll promote the input to the larger type.
454 SmallerValueMentioned |= OutSize < InSize;
457 // If the smaller value wasn't mentioned in the asm string, and if the
458 // output was a register, just extend the shorter one to the size of the
460 if (!SmallerValueMentioned && InputDomain != AD_Other &&
461 OutputConstraintInfos[TiedTo].allowsRegister())
464 // Either both of the operands were mentioned or the smaller one was
465 // mentioned. One more special case that we'll allow: if the tied input is
466 // integer, unmentioned, and is a constant, then we'll allow truncating it
467 // down to the size of the destination.
468 if (InputDomain == AD_Int && OutputDomain == AD_Int &&
469 !isOperandMentioned(InputOpNo, Pieces) &&
470 InputExpr->isEvaluatable(Context)) {
472 (OutTy->isBooleanType() ? CK_IntegralToBoolean : CK_IntegralCast);
473 InputExpr = ImpCastExprToType(InputExpr, OutTy, castKind).get();
474 Exprs[InputOpNo] = InputExpr;
475 NS->setInputExpr(i, InputExpr);
479 Diag(InputExpr->getLocStart(),
480 diag::err_asm_tying_incompatible_types)
481 << InTy << OutTy << OutputExpr->getSourceRange()
482 << InputExpr->getSourceRange();
489 ExprResult Sema::LookupInlineAsmIdentifier(CXXScopeSpec &SS,
490 SourceLocation TemplateKWLoc,
492 llvm::InlineAsmIdentifierInfo &Info,
493 bool IsUnevaluatedContext) {
496 if (IsUnevaluatedContext)
497 PushExpressionEvaluationContext(UnevaluatedAbstract,
498 ReuseLambdaContextDecl);
500 ExprResult Result = ActOnIdExpression(getCurScope(), SS, TemplateKWLoc, Id,
501 /*trailing lparen*/ false,
502 /*is & operand*/ false,
503 /*CorrectionCandidateCallback=*/nullptr,
504 /*IsInlineAsmIdentifier=*/ true);
506 if (IsUnevaluatedContext)
507 PopExpressionEvaluationContext();
509 if (!Result.isUsable()) return Result;
511 Result = CheckPlaceholderExpr(Result.get());
512 if (!Result.isUsable()) return Result;
514 // Referring to parameters is not allowed in naked functions.
515 if (CheckNakedParmReference(Result.get(), *this))
518 QualType T = Result.get()->getType();
520 // For now, reject dependent types.
521 if (T->isDependentType()) {
522 Diag(Id.getLocStart(), diag::err_asm_incomplete_type) << T;
526 // Any sort of function type is fine.
527 if (T->isFunctionType()) {
531 // Otherwise, it needs to be a complete type.
532 if (RequireCompleteExprType(Result.get(), diag::err_asm_incomplete_type)) {
536 // Compute the type size (and array length if applicable?).
537 Info.Type = Info.Size = Context.getTypeSizeInChars(T).getQuantity();
538 if (T->isArrayType()) {
539 const ArrayType *ATy = Context.getAsArrayType(T);
540 Info.Type = Context.getTypeSizeInChars(ATy->getElementType()).getQuantity();
541 Info.Length = Info.Size / Info.Type;
544 // We can work with the expression as long as it's not an r-value.
545 if (!Result.get()->isRValue())
546 Info.IsVarDecl = true;
551 bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member,
552 unsigned &Offset, SourceLocation AsmLoc) {
554 LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(),
557 if (!LookupName(BaseResult, getCurScope()))
560 if (!BaseResult.isSingleResult())
563 const RecordType *RT = nullptr;
564 NamedDecl *FoundDecl = BaseResult.getFoundDecl();
565 if (VarDecl *VD = dyn_cast<VarDecl>(FoundDecl))
566 RT = VD->getType()->getAs<RecordType>();
567 else if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(FoundDecl)) {
568 MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false);
569 RT = TD->getUnderlyingType()->getAs<RecordType>();
570 } else if (TypeDecl *TD = dyn_cast<TypeDecl>(FoundDecl))
571 RT = TD->getTypeForDecl()->getAs<RecordType>();
575 if (RequireCompleteType(AsmLoc, QualType(RT, 0), 0))
578 LookupResult FieldResult(*this, &Context.Idents.get(Member), SourceLocation(),
581 if (!LookupQualifiedName(FieldResult, RT->getDecl()))
584 // FIXME: Handle IndirectFieldDecl?
585 FieldDecl *FD = dyn_cast<FieldDecl>(FieldResult.getFoundDecl());
589 const ASTRecordLayout &RL = Context.getASTRecordLayout(RT->getDecl());
590 unsigned i = FD->getFieldIndex();
591 CharUnits Result = Context.toCharUnitsFromBits(RL.getFieldOffset(i));
592 Offset = (unsigned)Result.getQuantity();
597 StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
598 ArrayRef<Token> AsmToks,
600 unsigned NumOutputs, unsigned NumInputs,
601 ArrayRef<StringRef> Constraints,
602 ArrayRef<StringRef> Clobbers,
603 ArrayRef<Expr*> Exprs,
604 SourceLocation EndLoc) {
605 bool IsSimple = (NumOutputs != 0 || NumInputs != 0);
606 getCurFunction()->setHasBranchProtectedScope();
608 new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, IsSimple,
609 /*IsVolatile*/ true, AsmToks, NumOutputs, NumInputs,
610 Constraints, Exprs, AsmString,
615 LabelDecl *Sema::GetOrCreateMSAsmLabel(StringRef ExternalLabelName,
616 SourceLocation Location,
618 LabelDecl* Label = LookupOrCreateLabel(PP.getIdentifierInfo(ExternalLabelName),
621 if (Label->isMSAsmLabel()) {
622 // If we have previously created this label implicitly, mark it as used.
623 Label->markUsed(Context);
625 // Otherwise, insert it, but only resolve it if we have seen the label itself.
626 std::string InternalName;
627 llvm::raw_string_ostream OS(InternalName);
628 // Create an internal name for the label. The name should not be a valid mangled
629 // name, and should be unique. We use a dot to make the name an invalid mangled
631 OS << "__MSASMLABEL_." << MSAsmLabelNameCounter++ << "__" << ExternalLabelName;
632 Label->setMSAsmLabel(OS.str());
635 // The label might have been created implicitly from a previously encountered
636 // goto statement. So, for both newly created and looked up labels, we mark
638 Label->setMSAsmLabelResolved();
640 // Adjust their location for being able to generate accurate diagnostics.
641 Label->setLocation(Location);