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llvm-project/clang/lib/Sema/SemaStmtAsm.cpp

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//===--- 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<GCCAsmStmt::AsmStringPiece> 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<FunctionDecl>(S.CurContext);
if (!Func)
return false;
if (!Func->hasAttr<NakedAttr>())
return false;
SmallVector<Expr*, 4> WorkList;
WorkList.push_back(E);
while (WorkList.size()) {
Expr *E = WorkList.pop_back_val();
if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
if (isa<ParmVarDecl>(DRE->getDecl())) {
S.Diag(DRE->getLocStart(), diag::err_asm_naked_parm_ref);
S.Diag(Func->getAttr<NakedAttr>()->getLocation(), diag::note_attribute);
return true;
}
}
for (Stmt *Child : E->children()) {
if (Expr *E = dyn_cast_or_null<Expr>(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<StringLiteral**>(constraints.data());
StringLiteral *AsmString = cast<StringLiteral>(asmString);
StringLiteral **Clobbers = reinterpret_cast<StringLiteral**>(clobbers.data());
SmallVector<TargetInfo::ConstraintInfo, 4> 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<TargetInfo::ConstraintInfo, 4> 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_invalid_type_in_input)
<< InputExpr->getType() << 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<GCCAsmStmt::AsmStringPiece, 8> 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<VarDecl>(FoundDecl))
RT = VD->getType()->getAs<RecordType>();
else if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(FoundDecl)) {
MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false);
RT = TD->getUnderlyingType()->getAs<RecordType>();
} else if (TypeDecl *TD = dyn_cast<TypeDecl>(FoundDecl))
RT = TD->getTypeForDecl()->getAs<RecordType>();
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<FieldDecl>(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<Token> AsmToks,
StringRef AsmString,
unsigned NumOutputs, unsigned NumInputs,
ArrayRef<StringRef> Constraints,
ArrayRef<StringRef> Clobbers,
ArrayRef<Expr*> 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;
}
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