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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/Sema/Scope.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Lookup.h"
#include "clang/AST/TypeLoc.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstPrinter.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCTargetAsmParser.h"
#include "llvm/MC/MCParser/MCAsmLexer.h"
#include "llvm/MC/MCParser/MCAsmParser.h"
#include "llvm/MC/MCParser/MCParsedAsmOperand.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/TargetSelect.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;
}
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());
Expr **Exprs = exprs.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.
if (!AsmString->isAscii())
return StmtError(Diag(AsmString->getLocStart(),diag::err_asm_wide_character)
<< AsmString->getSourceRange());
for (unsigned i = 0; i != NumOutputs; i++) {
StringLiteral *Literal = Constraints[i];
if (!Literal->isAscii())
return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
<< Literal->getSourceRange());
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());
// Check that the output exprs are valid lvalues.
Expr *OutputExpr = Exprs[i];
if (CheckAsmLValue(OutputExpr, *this)) {
return StmtError(Diag(OutputExpr->getLocStart(),
diag::err_asm_invalid_lvalue_in_output)
<< OutputExpr->getSourceRange());
}
OutputConstraintInfos.push_back(Info);
}
SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
for (unsigned i = NumOutputs, e = NumOutputs + NumInputs; i != e; i++) {
StringLiteral *Literal = Constraints[i];
if (!Literal->isAscii())
return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
<< Literal->getSourceRange());
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());
}
Expr *InputExpr = Exprs[i];
// 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());
}
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());
}
}
ExprResult Result = DefaultFunctionArrayLvalueConversion(Exprs[i]);
if (Result.isInvalid())
return StmtError();
Exprs[i] = Result.take();
InputConstraintInfos.push_back(Info);
}
// Check that the clobbers are valid.
for (unsigned i = 0; i != NumClobbers; i++) {
StringLiteral *Literal = Clobbers[i];
if (!Literal->isAscii())
return StmtError(Diag(Literal->getLocStart(),diag::err_asm_wide_character)
<< Literal->getSourceRange());
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, 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 tied input operands for type mismatches.
for (unsigned i = 0, e = InputConstraintInfos.size(); i != e; ++i) {
TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
// 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).take();
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 Owned(NS);
}
// getSpelling - Get the spelling of the AsmTok token.
static StringRef getSpelling(Sema &SemaRef, Token AsmTok) {
StringRef Asm;
SmallString<512> TokenBuf;
TokenBuf.resize(512);
bool StringInvalid = false;
Asm = SemaRef.PP.getSpelling(AsmTok, TokenBuf, &StringInvalid);
assert (!StringInvalid && "Expected valid string!");
return Asm;
}
// Build the inline assembly string. Returns true on error.
static bool buildMSAsmString(Sema &SemaRef,
SourceLocation AsmLoc,
ArrayRef<Token> AsmToks,
std::string &AsmString) {
assert (!AsmToks.empty() && "Didn't expect an empty AsmToks!");
SmallString<512> Asm;
for (unsigned i = 0, e = AsmToks.size(); i < e; ++i) {
bool isNewAsm = ((i == 0) ||
AsmToks[i].isAtStartOfLine() ||
AsmToks[i].is(tok::kw_asm));
if (isNewAsm) {
if (i != 0)
Asm += "\n\t";
if (AsmToks[i].is(tok::kw_asm)) {
i++; // Skip __asm
if (i == e) {
SemaRef.Diag(AsmLoc, diag::err_asm_empty);
return true;
}
}
}
if (i && AsmToks[i].hasLeadingSpace() && !isNewAsm)
Asm += ' ';
StringRef Spelling = getSpelling(SemaRef, AsmToks[i]);
Asm += Spelling;
}
AsmString = Asm.str();
return false;
}
namespace {
enum AsmOpRewriteKind {
AOK_Imm,
AOK_Input,
AOK_Output
};
struct AsmOpRewrite {
AsmOpRewriteKind Kind;
llvm::SMLoc Loc;
unsigned Len;
public:
AsmOpRewrite(AsmOpRewriteKind kind, llvm::SMLoc loc, unsigned len)
: Kind(kind), Loc(loc), Len(len) { }
};
}
StmtResult Sema::ActOnMSAsmStmt(SourceLocation AsmLoc, SourceLocation LBraceLoc,
ArrayRef<Token> AsmToks,SourceLocation EndLoc) {
SmallVector<IdentifierInfo*, 4> Inputs;
SmallVector<IdentifierInfo*, 4> Outputs;
SmallVector<Expr*, 4> InputExprs;
SmallVector<Expr*, 4> OutputExprs;
SmallVector<StringRef, 4> Constraints;
SmallVector<std::string, 4> InputConstraints;
SmallVector<std::string, 4> OutputConstraints;
SmallVector<StringRef, 4> Clobbers;
std::set<std::string> ClobberRegs;
SmallVector<struct AsmOpRewrite, 4> AsmStrRewrites;
// Empty asm statements don't need to instantiate the AsmParser, etc.
if (AsmToks.empty()) {
StringRef EmptyAsmStr;
MSAsmStmt *NS =
new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, /*IsSimple*/ true,
/*IsVolatile*/ true, AsmToks, Inputs, Outputs,
InputExprs, OutputExprs, EmptyAsmStr, Constraints,
Clobbers, EndLoc);
return Owned(NS);
}
std::string AsmString;
if (buildMSAsmString(*this, AsmLoc, AsmToks, AsmString))
return StmtError();
// Get the target specific parser.
std::string Error;
const std::string &TT = Context.getTargetInfo().getTriple().getTriple();
const llvm::Target *TheTarget(llvm::TargetRegistry::lookupTarget(TT, Error));
OwningPtr<llvm::MCAsmInfo> MAI(TheTarget->createMCAsmInfo(TT));
OwningPtr<llvm::MCRegisterInfo> MRI(TheTarget->createMCRegInfo(TT));
OwningPtr<llvm::MCObjectFileInfo> MOFI(new llvm::MCObjectFileInfo());
OwningPtr<llvm::MCSubtargetInfo>
STI(TheTarget->createMCSubtargetInfo(TT, "", ""));
llvm::SourceMgr SrcMgr;
llvm::MCContext Ctx(*MAI, *MRI, MOFI.get(), &SrcMgr);
llvm::MemoryBuffer *Buffer =
llvm::MemoryBuffer::getMemBuffer(AsmString, "<inline asm>");
// Tell SrcMgr about this buffer, which is what the parser will pick up.
SrcMgr.AddNewSourceBuffer(Buffer, llvm::SMLoc());
OwningPtr<llvm::MCStreamer> Str(createNullStreamer(Ctx));
OwningPtr<llvm::MCAsmParser>
Parser(createMCAsmParser(SrcMgr, Ctx, *Str.get(), *MAI));
OwningPtr<llvm::MCTargetAsmParser>
TargetParser(TheTarget->createMCAsmParser(*STI, *Parser));
Parser->setParsingInlineAsm(true);
// Get the instruction descriptor.
const llvm::MCInstrInfo *MII = TheTarget->createMCInstrInfo();
llvm::MCInstPrinter *IP =
TheTarget->createMCInstPrinter(1, *MAI, *MII, *MRI, *STI);
// Change to the Intel dialect.
Parser->setAssemblerDialect(1);
Parser->setTargetParser(*TargetParser.get());
Parser->setParsingInlineAsm(true);
// Prime the lexer.
Parser->Lex();
// While we have input, parse each statement.
unsigned InputIdx = 0;
unsigned OutputIdx = 0;
while (Parser->getLexer().isNot(llvm::AsmToken::Eof)) {
if (Parser->ParseStatement()) {
// FIXME: The AsmParser should report errors, but we could potentially be
// more verbose here.
break;
}
if (Parser->isInstruction()) {
const llvm::MCInstrDesc &Desc = MII->get(Parser->getOpcode());
// Build the list of clobbers, outputs and inputs.
for (unsigned i = 1, e = Parser->getNumParsedOperands(); i != e; ++i) {
llvm::MCParsedAsmOperand &Operand = Parser->getParsedOperand(i);
// Immediate.
if (Operand.isImm()) {
AsmStrRewrites.push_back(AsmOpRewrite(AOK_Imm,
Operand.getStartLoc(),
Operand.getNameLen()));
continue;
}
// Register operand.
if (Operand.isReg()) {
unsigned NumDefs = Desc.getNumDefs();
// Clobber.
if (NumDefs && Operand.getMCOperandNum() < NumDefs) {
std::string Reg;
llvm::raw_string_ostream OS(Reg);
IP->printRegName(OS, Operand.getReg());
StringRef Clobber(OS.str());
if (!Context.getTargetInfo().isValidClobber(Clobber))
return StmtError(
Diag(AsmLoc, diag::err_asm_unknown_register_name) << Clobber);
ClobberRegs.insert(Reg);
}
continue;
}
// Expr/Input or Output.
StringRef Name = Operand.getName();
if (IdentifierInfo *II = &Context.Idents.get(Name)) {
CXXScopeSpec SS;
UnqualifiedId Id;
SourceLocation Loc;
Id.setIdentifier(II, AsmLoc);
ExprResult Result = ActOnIdExpression(getCurScope(), SS, Loc, Id,
false, false);
if (!Result.isInvalid()) {
bool isOutput = (i == 1) && Desc.mayStore();
if (isOutput) {
std::string Constraint = "=";
++InputIdx;
Outputs.push_back(II);
OutputExprs.push_back(Result.take());
Constraint += Operand.getConstraint().str();
OutputConstraints.push_back(Constraint);
AsmStrRewrites.push_back(AsmOpRewrite(AOK_Output,
Operand.getStartLoc(),
Operand.getNameLen()));
} else {
Inputs.push_back(II);
InputExprs.push_back(Result.take());
InputConstraints.push_back(Operand.getConstraint().str());
AsmStrRewrites.push_back(AsmOpRewrite(AOK_Input,
Operand.getStartLoc(),
Operand.getNameLen()));
}
}
}
}
Parser->freeParsedOperands();
}
}
for (std::set<std::string>::iterator I = ClobberRegs.begin(),
E = ClobberRegs.end(); I != E; ++I)
Clobbers.push_back(*I);
// Merge the output and input constraints. Output constraints are expected
// first.
for (SmallVectorImpl<std::string>::iterator I = OutputConstraints.begin(),
E = OutputConstraints.end(); I != E; ++I)
Constraints.push_back(*I);
for (SmallVectorImpl<std::string>::iterator I = InputConstraints.begin(),
E = InputConstraints.end(); I != E; ++I)
Constraints.push_back(*I);
// Build the IR assembly string.
std::string AsmStringIR;
llvm::raw_string_ostream OS(AsmStringIR);
const char *Start = AsmString.c_str();
for (SmallVectorImpl<struct AsmOpRewrite>::iterator I = AsmStrRewrites.begin(),
E = AsmStrRewrites.end(); I != E; ++I) {
const char *Loc = (*I).Loc.getPointer();
// Emit everything up to the immediate/expression.
OS << StringRef(Start, Loc - Start);
// Rewrite expressions in $N notation.
switch ((*I).Kind) {
case AOK_Imm:
OS << Twine("$$") + StringRef(Loc, (*I).Len);
break;
case AOK_Input:
OS << '$';
OS << InputIdx++;
break;
case AOK_Output:
OS << '$';
OS << OutputIdx++;
break;
}
// Skip the original expression.
Start = Loc + (*I).Len;
}
// Emit the remainder of the asm string.
const char *AsmEnd = AsmString.c_str() + AsmString.size();
if (Start != AsmEnd)
OS << StringRef(Start, AsmEnd - Start);
AsmString = OS.str();
MSAsmStmt *NS =
new (Context) MSAsmStmt(Context, AsmLoc, LBraceLoc, /*IsSimple*/ false,
/*IsVolatile*/ true, AsmToks, Inputs, Outputs,
InputExprs, OutputExprs, AsmString, Constraints,
Clobbers, EndLoc);
return Owned(NS);
}
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