// FIXME: This should just be implemented as a patch to
// X86TargetAsmInfo.cpp, then everyone will benefit.
bool RaiseAsmPass::runOnInstruction(Module &M, Instruction *I) {
// We can just raise inline assembler using calls
CallInst *ci = dyn_cast<CallInst>(I);
if (!ci)
return false;
InlineAsm *ia = dyn_cast<InlineAsm>(ci->getCalledValue());
if (!ia)
return false;
// Try to use existing infrastructure
if (!TLI)
return false;
if (TLI->ExpandInlineAsm(ci))
return true;
if (triple.getArch() == llvm::Triple::x86_64 &&
triple.getOS() == llvm::Triple::Linux) {
if (ia->getAsmString() == "" && ia->hasSideEffects()) {
#if LLVM_VERSION_CODE >= LLVM_VERSION(3, 3)
IRBuilder<> Builder(I);
Builder.CreateFence(llvm::SequentiallyConsistent);
#endif
I->eraseFromParent();
return true;
}
}
return false;
}
bool X86TargetAsmInfo<BaseTAI>::ExpandInlineAsm(CallInst *CI) const {
InlineAsm *IA = cast<InlineAsm>(CI->getCalledValue());
std::vector<InlineAsm::ConstraintInfo> Constraints = IA->ParseConstraints();
std::string AsmStr = IA->getAsmString();
// TODO: should remove alternatives from the asmstring: "foo {a|b}" -> "foo a"
std::vector<std::string> AsmPieces;
SplitString(AsmStr, AsmPieces, "\n"); // ; as separator?
switch (AsmPieces.size()) {
default: return false;
case 1:
AsmStr = AsmPieces[0];
AsmPieces.clear();
SplitString(AsmStr, AsmPieces, " \t"); // Split with whitespace.
// bswap $0
if (AsmPieces.size() == 2 &&
(AsmPieces[0] == "bswap" ||
AsmPieces[0] == "bswapq" ||
AsmPieces[0] == "bswapl") &&
(AsmPieces[1] == "$0" ||
AsmPieces[1] == "${0:q}")) {
// No need to check constraints, nothing other than the equivalent of
// "=r,0" would be valid here.
return LowerToBSwap(CI);
}
// rorw $$8, ${0:w} --> llvm.bswap.i16
if (CI->getType() == Type::Int16Ty &&
AsmPieces.size() == 3 &&
AsmPieces[0] == "rorw" &&
AsmPieces[1] == "$$8," &&
AsmPieces[2] == "${0:w}" &&
IA->getConstraintString() == "=r,0,~{dirflag},~{fpsr},~{flags},~{cc}") {
return LowerToBSwap(CI);
}
break;
case 3:
if (CI->getType() == Type::Int64Ty && Constraints.size() >= 2 &&
Constraints[0].Codes.size() == 1 && Constraints[0].Codes[0] == "A" &&
Constraints[1].Codes.size() == 1 && Constraints[1].Codes[0] == "0") {
// bswap %eax / bswap %edx / xchgl %eax, %edx -> llvm.bswap.i64
std::vector<std::string> Words;
SplitString(AsmPieces[0], Words, " \t");
if (Words.size() == 2 && Words[0] == "bswap" && Words[1] == "%eax") {
Words.clear();
SplitString(AsmPieces[1], Words, " \t");
if (Words.size() == 2 && Words[0] == "bswap" && Words[1] == "%edx") {
Words.clear();
SplitString(AsmPieces[2], Words, " \t,");
if (Words.size() == 3 && Words[0] == "xchgl" && Words[1] == "%eax" &&
Words[2] == "%edx") {
return LowerToBSwap(CI);
}
}
}
}
break;
}
return false;
}
