//===--- SemaStmtAsm.cpp - Semantic Analysis for Asm Statements -----------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements semantic analysis for inline asm statements. // //===----------------------------------------------------------------------===// #include "clang/Sema/SemaInternal.h" #include "clang/AST/RecordLayout.h" #include "clang/AST/TypeLoc.h" #include "clang/Basic/TargetInfo.h" #include "clang/Lex/Preprocessor.h" #include "clang/Sema/Initialization.h" #include "clang/Sema/Lookup.h" #include "clang/Sema/Scope.h" #include "clang/Sema/ScopeInfo.h" #include "llvm/ADT/ArrayRef.h" #include "llvm/ADT/BitVector.h" #include "llvm/MC/MCParser/MCAsmParser.h" using namespace clang; using namespace sema; /// CheckAsmLValue - GNU C has an extremely ugly extension whereby they silently /// ignore "noop" casts in places where an lvalue is required by an inline asm. /// We emulate this behavior when -fheinous-gnu-extensions is specified, but /// provide a strong guidance to not use it. /// /// This method checks to see if the argument is an acceptable l-value and /// returns false if it is a case we can handle. static bool CheckAsmLValue(const Expr *E, Sema &S) { // Type dependent expressions will be checked during instantiation. if (E->isTypeDependent()) return false; if (E->isLValue()) return false; // Cool, this is an lvalue. // Okay, this is not an lvalue, but perhaps it is the result of a cast that we // are supposed to allow. const Expr *E2 = E->IgnoreParenNoopCasts(S.Context); if (E != E2 && E2->isLValue()) { if (!S.getLangOpts().HeinousExtensions) S.Diag(E2->getLocStart(), diag::err_invalid_asm_cast_lvalue) << E->getSourceRange(); else S.Diag(E2->getLocStart(), diag::warn_invalid_asm_cast_lvalue) << E->getSourceRange(); // Accept, even if we emitted an error diagnostic. return false; } // None of the above, just randomly invalid non-lvalue. return true; } /// isOperandMentioned - Return true if the specified operand # is mentioned /// anywhere in the decomposed asm string. static bool isOperandMentioned(unsigned OpNo, ArrayRef AsmStrPieces) { for (unsigned p = 0, e = AsmStrPieces.size(); p != e; ++p) { const GCCAsmStmt::AsmStringPiece &Piece = AsmStrPieces[p]; if (!Piece.isOperand()) continue; // If this is a reference to the input and if the input was the smaller // one, then we have to reject this asm. if (Piece.getOperandNo() == OpNo) return true; } return false; } static bool CheckNakedParmReference(Expr *E, Sema &S) { FunctionDecl *Func = dyn_cast(S.CurContext); if (!Func) return false; if (!Func->hasAttr()) return false; SmallVector WorkList; WorkList.push_back(E); while (WorkList.size()) { Expr *E = WorkList.pop_back_val(); if (DeclRefExpr *DRE = dyn_cast(E)) { if (isa(DRE->getDecl())) { S.Diag(DRE->getLocStart(), diag::err_asm_naked_parm_ref); S.Diag(Func->getAttr()->getLocation(), diag::note_attribute); return true; } } for (Stmt *Child : E->children()) { if (Expr *E = dyn_cast_or_null(Child)) WorkList.push_back(E); } } return false; } StmtResult Sema::ActOnGCCAsmStmt(SourceLocation AsmLoc, bool IsSimple, bool IsVolatile, unsigned NumOutputs, unsigned NumInputs, IdentifierInfo **Names, MultiExprArg constraints, MultiExprArg Exprs, Expr *asmString, MultiExprArg clobbers, SourceLocation RParenLoc) { unsigned NumClobbers = clobbers.size(); StringLiteral **Constraints = reinterpret_cast(constraints.data()); StringLiteral *AsmString = cast(asmString); StringLiteral **Clobbers = reinterpret_cast(clobbers.data()); SmallVector OutputConstraintInfos; // The parser verifies that there is a string literal here. assert(AsmString->isAscii()); for (unsigned i = 0; i != NumOutputs; i++) { StringLiteral *Literal = Constraints[i]; assert(Literal->isAscii()); StringRef OutputName; if (Names[i]) OutputName = Names[i]->getName(); TargetInfo::ConstraintInfo Info(Literal->getString(), OutputName); if (!Context.getTargetInfo().validateOutputConstraint(Info)) return StmtError(Diag(Literal->getLocStart(), diag::err_asm_invalid_output_constraint) << Info.getConstraintStr()); ExprResult ER = CheckPlaceholderExpr(Exprs[i]); if (ER.isInvalid()) return StmtError(); Exprs[i] = ER.get(); // Check that the output exprs are valid lvalues. Expr *OutputExpr = Exprs[i]; // Referring to parameters is not allowed in naked functions. if (CheckNakedParmReference(OutputExpr, *this)) return StmtError(); OutputConstraintInfos.push_back(Info); // If this is dependent, just continue. if (OutputExpr->isTypeDependent()) continue; Expr::isModifiableLvalueResult IsLV = OutputExpr->isModifiableLvalue(Context, /*Loc=*/nullptr); switch (IsLV) { case Expr::MLV_Valid: // Cool, this is an lvalue. break; case Expr::MLV_ArrayType: // This is OK too. break; case Expr::MLV_LValueCast: { const Expr *LVal = OutputExpr->IgnoreParenNoopCasts(Context); if (!getLangOpts().HeinousExtensions) { Diag(LVal->getLocStart(), diag::err_invalid_asm_cast_lvalue) << OutputExpr->getSourceRange(); } else { Diag(LVal->getLocStart(), diag::warn_invalid_asm_cast_lvalue) << OutputExpr->getSourceRange(); } // Accept, even if we emitted an error diagnostic. break; } case Expr::MLV_IncompleteType: case Expr::MLV_IncompleteVoidType: if (RequireCompleteType(OutputExpr->getLocStart(), Exprs[i]->getType(), diag::err_dereference_incomplete_type)) return StmtError(); default: return StmtError(Diag(OutputExpr->getLocStart(), diag::err_asm_invalid_lvalue_in_output) << OutputExpr->getSourceRange()); } unsigned Size = Context.getTypeSize(OutputExpr->getType()); if (!Context.getTargetInfo().validateOutputSize(Literal->getString(), Size)) return StmtError(Diag(OutputExpr->getLocStart(), diag::err_asm_invalid_output_size) << Info.getConstraintStr()); } SmallVector InputConstraintInfos; for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) { StringLiteral *Literal = Constraints[i]; assert(Literal->isAscii()); StringRef InputName; if (Names[i]) InputName = Names[i]->getName(); TargetInfo::ConstraintInfo Info(Literal->getString(), InputName); if (!Context.getTargetInfo().validateInputConstraint(OutputConstraintInfos.data(), NumOutputs, Info)) { return StmtError(Diag(Literal->getLocStart(), diag::err_asm_invalid_input_constraint) << Info.getConstraintStr()); } ExprResult ER = CheckPlaceholderExpr(Exprs[i]); if (ER.isInvalid()) return StmtError(); Exprs[i] = ER.get(); Expr *InputExpr = Exprs[i]; // Referring to parameters is not allowed in naked functions. if (CheckNakedParmReference(InputExpr, *this)) return StmtError(); // Only allow void types for memory constraints. if (Info.allowsMemory() && !Info.allowsRegister()) { if (CheckAsmLValue(InputExpr, *this)) return StmtError(Diag(InputExpr->getLocStart(), diag::err_asm_invalid_lvalue_in_input) << Info.getConstraintStr() << InputExpr->getSourceRange()); } else if (Info.requiresImmediateConstant() && !Info.allowsRegister()) { llvm::APSInt Result; if (!InputExpr->EvaluateAsInt(Result, Context)) return StmtError( Diag(InputExpr->getLocStart(), diag::err_asm_immediate_expected) << Info.getConstraintStr() << InputExpr->getSourceRange()); if (Result.slt(Info.getImmConstantMin()) || Result.sgt(Info.getImmConstantMax())) return StmtError(Diag(InputExpr->getLocStart(), diag::err_invalid_asm_value_for_constraint) << Result.toString(10) << Info.getConstraintStr() << InputExpr->getSourceRange()); } else { ExprResult Result = DefaultFunctionArrayLvalueConversion(Exprs[i]); if (Result.isInvalid()) return StmtError(); Exprs[i] = Result.get(); } if (Info.allowsRegister()) { if (InputExpr->getType()->isVoidType()) { return StmtError(Diag(InputExpr->getLocStart(), diag::err_asm_invalid_type_in_input) << InputExpr->getType() << Info.getConstraintStr() << InputExpr->getSourceRange()); } } InputConstraintInfos.push_back(Info); const Type *Ty = Exprs[i]->getType().getTypePtr(); if (Ty->isDependentType()) continue; if (!Ty->isVoidType() || !Info.allowsMemory()) if (RequireCompleteType(InputExpr->getLocStart(), Exprs[i]->getType(), diag::err_dereference_incomplete_type)) return StmtError(); unsigned Size = Context.getTypeSize(Ty); if (!Context.getTargetInfo().validateInputSize(Literal->getString(), Size)) return StmtError(Diag(InputExpr->getLocStart(), diag::err_asm_invalid_input_size) << Info.getConstraintStr()); } // Check that the clobbers are valid. for (unsigned i = 0; i != NumClobbers; i++) { StringLiteral *Literal = Clobbers[i]; assert(Literal->isAscii()); StringRef Clobber = Literal->getString(); if (!Context.getTargetInfo().isValidClobber(Clobber)) return StmtError(Diag(Literal->getLocStart(), diag::err_asm_unknown_register_name) << Clobber); } GCCAsmStmt *NS = new (Context) GCCAsmStmt(Context, AsmLoc, IsSimple, IsVolatile, NumOutputs, NumInputs, Names, Constraints, Exprs.data(), AsmString, NumClobbers, Clobbers, RParenLoc); // Validate the asm string, ensuring it makes sense given the operands we // have. SmallVector Pieces; unsigned DiagOffs; if (unsigned DiagID = NS->AnalyzeAsmString(Pieces, Context, DiagOffs)) { Diag(getLocationOfStringLiteralByte(AsmString, DiagOffs), DiagID) << AsmString->getSourceRange(); return StmtError(); } // Validate constraints and modifiers. for (unsigned i = 0, e = Pieces.size(); i != e; ++i) { GCCAsmStmt::AsmStringPiece &Piece = Pieces[i]; if (!Piece.isOperand()) continue; // Look for the correct constraint index. unsigned Idx = 0; unsigned ConstraintIdx = 0; for (unsigned i = 0, e = NS->getNumOutputs(); i != e; ++i, ++ConstraintIdx) { TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i]; if (Idx == Piece.getOperandNo()) break; ++Idx; if (Info.isReadWrite()) { if (Idx == Piece.getOperandNo()) break; ++Idx; } } for (unsigned i = 0, e = NS->getNumInputs(); i != e; ++i, ++ConstraintIdx) { TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; if (Idx == Piece.getOperandNo()) break; ++Idx; if (Info.isReadWrite()) { if (Idx == Piece.getOperandNo()) break; ++Idx; } } // Now that we have the right indexes go ahead and check. StringLiteral *Literal = Constraints[ConstraintIdx]; const Type *Ty = Exprs[ConstraintIdx]->getType().getTypePtr(); if (Ty->isDependentType() || Ty->isIncompleteType()) continue; unsigned Size = Context.getTypeSize(Ty); std::string SuggestedModifier; if (!Context.getTargetInfo().validateConstraintModifier( Literal->getString(), Piece.getModifier(), Size, SuggestedModifier)) { Diag(Exprs[ConstraintIdx]->getLocStart(), diag::warn_asm_mismatched_size_modifier); if (!SuggestedModifier.empty()) { auto B = Diag(Piece.getRange().getBegin(), diag::note_asm_missing_constraint_modifier) << SuggestedModifier; SuggestedModifier = "%" + SuggestedModifier + Piece.getString(); B.AddFixItHint(FixItHint::CreateReplacement(Piece.getRange(), SuggestedModifier)); } } } // Validate tied input operands for type mismatches. unsigned NumAlternatives = ~0U; for (unsigned i = 0, e = OutputConstraintInfos.size(); i != e; ++i) { TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i]; StringRef ConstraintStr = Info.getConstraintStr(); unsigned AltCount = ConstraintStr.count(',') + 1; if (NumAlternatives == ~0U) NumAlternatives = AltCount; else if (NumAlternatives != AltCount) return StmtError(Diag(NS->getOutputExpr(i)->getLocStart(), diag::err_asm_unexpected_constraint_alternatives) << NumAlternatives << AltCount); } for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) { TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i]; StringRef ConstraintStr = Info.getConstraintStr(); unsigned AltCount = ConstraintStr.count(',') + 1; if (NumAlternatives == ~0U) NumAlternatives = AltCount; else if (NumAlternatives != AltCount) return StmtError(Diag(NS->getInputExpr(i)->getLocStart(), diag::err_asm_unexpected_constraint_alternatives) << NumAlternatives << AltCount); // If this is a tied constraint, verify that the output and input have // either exactly the same type, or that they are int/ptr operands with the // same size (int/long, int*/long, are ok etc). if (!Info.hasTiedOperand()) continue; unsigned TiedTo = Info.getTiedOperand(); unsigned InputOpNo = i+NumOutputs; Expr *OutputExpr = Exprs[TiedTo]; Expr *InputExpr = Exprs[InputOpNo]; if (OutputExpr->isTypeDependent() || InputExpr->isTypeDependent()) continue; QualType InTy = InputExpr->getType(); QualType OutTy = OutputExpr->getType(); if (Context.hasSameType(InTy, OutTy)) continue; // All types can be tied to themselves. // Decide if the input and output are in the same domain (integer/ptr or // floating point. enum AsmDomain { AD_Int, AD_FP, AD_Other } InputDomain, OutputDomain; if (InTy->isIntegerType() || InTy->isPointerType()) InputDomain = AD_Int; else if (InTy->isRealFloatingType()) InputDomain = AD_FP; else InputDomain = AD_Other; if (OutTy->isIntegerType() || OutTy->isPointerType()) OutputDomain = AD_Int; else if (OutTy->isRealFloatingType()) OutputDomain = AD_FP; else OutputDomain = AD_Other; // They are ok if they are the same size and in the same domain. This // allows tying things like: // void* to int* // void* to int if they are the same size. // double to long double if they are the same size. // uint64_t OutSize = Context.getTypeSize(OutTy); uint64_t InSize = Context.getTypeSize(InTy); if (OutSize == InSize && InputDomain == OutputDomain && InputDomain != AD_Other) continue; // If the smaller input/output operand is not mentioned in the asm string, // then we can promote the smaller one to a larger input and the asm string // won't notice. bool SmallerValueMentioned = false; // If this is a reference to the input and if the input was the smaller // one, then we have to reject this asm. if (isOperandMentioned(InputOpNo, Pieces)) { // This is a use in the asm string of the smaller operand. Since we // codegen this by promoting to a wider value, the asm will get printed // "wrong". SmallerValueMentioned |= InSize < OutSize; } if (isOperandMentioned(TiedTo, Pieces)) { // If this is a reference to the output, and if the output is the larger // value, then it's ok because we'll promote the input to the larger type. SmallerValueMentioned |= OutSize < InSize; } // If the smaller value wasn't mentioned in the asm string, and if the // output was a register, just extend the shorter one to the size of the // larger one. if (!SmallerValueMentioned && InputDomain != AD_Other && OutputConstraintInfos[TiedTo].allowsRegister()) continue; // Either both of the operands were mentioned or the smaller one was // mentioned. One more special case that we'll allow: if the tied input is // integer, unmentioned, and is a constant, then we'll allow truncating it // down to the size of the destination. if (InputDomain == AD_Int && OutputDomain == AD_Int && !isOperandMentioned(InputOpNo, Pieces) && InputExpr->isEvaluatable(Context)) { CastKind castKind = (OutTy->isBooleanType() ? CK_IntegralToBoolean : CK_IntegralCast); InputExpr = ImpCastExprToType(InputExpr, OutTy, castKind).get(); Exprs[InputOpNo] = InputExpr; NS->setInputExpr(i, InputExpr); continue; } Diag(InputExpr->getLocStart(), diag::err_asm_tying_incompatible_types) << InTy << OutTy << OutputExpr->getSourceRange() << InputExpr->getSourceRange(); return StmtError(); } return NS; } ExprResult Sema::LookupInlineAsmIdentifier(CXXScopeSpec &SS, SourceLocation TemplateKWLoc, UnqualifiedId &Id, llvm::InlineAsmIdentifierInfo &Info, bool IsUnevaluatedContext) { Info.clear(); if (IsUnevaluatedContext) PushExpressionEvaluationContext(UnevaluatedAbstract, ReuseLambdaContextDecl); ExprResult Result = ActOnIdExpression(getCurScope(), SS, TemplateKWLoc, Id, /*trailing lparen*/ false, /*is & operand*/ false, /*CorrectionCandidateCallback=*/nullptr, /*IsInlineAsmIdentifier=*/ true); if (IsUnevaluatedContext) PopExpressionEvaluationContext(); if (!Result.isUsable()) return Result; Result = CheckPlaceholderExpr(Result.get()); if (!Result.isUsable()) return Result; // Referring to parameters is not allowed in naked functions. if (CheckNakedParmReference(Result.get(), *this)) return ExprError(); QualType T = Result.get()->getType(); // For now, reject dependent types. if (T->isDependentType()) { Diag(Id.getLocStart(), diag::err_asm_incomplete_type) << T; return ExprError(); } // Any sort of function type is fine. if (T->isFunctionType()) { return Result; } // Otherwise, it needs to be a complete type. if (RequireCompleteExprType(Result.get(), diag::err_asm_incomplete_type)) { return ExprError(); } // Compute the type size (and array length if applicable?). Info.Type = Info.Size = Context.getTypeSizeInChars(T).getQuantity(); if (T->isArrayType()) { const ArrayType *ATy = Context.getAsArrayType(T); Info.Type = Context.getTypeSizeInChars(ATy->getElementType()).getQuantity(); Info.Length = Info.Size / Info.Type; } // We can work with the expression as long as it's not an r-value. if (!Result.get()->isRValue()) Info.IsVarDecl = true; return Result; } bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member, unsigned &Offset, SourceLocation AsmLoc) { Offset = 0; LookupResult BaseResult(*this, &Context.Idents.get(Base), SourceLocation(), LookupOrdinaryName); if (!LookupName(BaseResult, getCurScope())) return true; if (!BaseResult.isSingleResult()) return true; const RecordType *RT = nullptr; NamedDecl *FoundDecl = BaseResult.getFoundDecl(); if (VarDecl *VD = dyn_cast(FoundDecl)) RT = VD->getType()->getAs(); else if (TypedefNameDecl *TD = dyn_cast(FoundDecl)) { MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false); RT = TD->getUnderlyingType()->getAs(); } else if (TypeDecl *TD = dyn_cast(FoundDecl)) RT = TD->getTypeForDecl()->getAs(); if (!RT) return true; if (RequireCompleteType(AsmLoc, QualType(RT, 0), 0)) return true; LookupResult FieldResult(*this, &Context.Idents.get(Member), SourceLocation(), LookupMemberName); if (!LookupQualifiedName(FieldResult, RT->getDecl())) return true; // FIXME: Handle IndirectFieldDecl? FieldDecl *FD = dyn_cast(FieldResult.getFoundDecl()); if (!FD) return true; const ASTRecordLayout &RL = Context.getASTRecordLayout(RT->getDecl()); unsigned i = FD->getFieldIndex(); CharUnits Result = Context.toCharUnitsFromBits(RL.getFieldOffset(i)); Offset = (unsigned)Result.getQuantity(); return false; } StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc, ArrayRef AsmToks, StringRef AsmString, unsigned NumOutputs, unsigned NumInputs, ArrayRef Constraints, ArrayRef Clobbers, ArrayRef Exprs, SourceLocation EndLoc) { bool IsSimple = (NumOutputs != 0 || NumInputs != 0); getCurFunction()->setHasBranchProtectedScope(); MSAsmStmt *NS = new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, IsSimple, /*IsVolatile*/ true, AsmToks, NumOutputs, NumInputs, Constraints, Exprs, AsmString, Clobbers, EndLoc); return NS; } LabelDecl *Sema::GetOrCreateMSAsmLabel(StringRef ExternalLabelName, SourceLocation Location, bool AlwaysCreate) { LabelDecl* Label = LookupOrCreateLabel(PP.getIdentifierInfo(ExternalLabelName), Location); if (Label->isMSAsmLabel()) { // If we have previously created this label implicitly, mark it as used. Label->markUsed(Context); } else { // Otherwise, insert it, but only resolve it if we have seen the label itself. std::string InternalName; llvm::raw_string_ostream OS(InternalName); // Create an internal name for the label. The name should not be a valid mangled // name, and should be unique. We use a dot to make the name an invalid mangled // name. OS << "__MSASMLABEL_." << MSAsmLabelNameCounter++ << "__" << ExternalLabelName; Label->setMSAsmLabel(OS.str()); } if (AlwaysCreate) { // The label might have been created implicitly from a previously encountered // goto statement. So, for both newly created and looked up labels, we mark // them as resolved. Label->setMSAsmLabelResolved(); } // Adjust their location for being able to generate accurate diagnostics. Label->setLocation(Location); return Label; }