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Fix lowering of cttz to work with signed values 

llvm-svn: 21874
This commit is contained in:
Chris Lattner 2005-05-11 20:02:14 +00:00
parent 9ec975a4b5
commit fe5759b022
1 changed files with 4 additions and 5 deletions
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9
llvm/lib/CodeGen/IntrinsicLowering.cpp
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@ -251,13 +251,12 @@ void DefaultIntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
break;
}
case Intrinsic::cttz: {
// cttz(x) -> ctpop(~X & (X-1))
Value *Src = CI->getOperand(1);
Value *NotSrc = BinaryOperator::createNot(Src, Src->getName()+".not", CI);
Src = BinaryOperator::createAnd(NotSrc,
BinaryOperator::createSub(Src,
ConstantUInt::get(CI->getOperand(0)->getType(), 1), "", CI));
Src = LowerCTPOP(Src, CI);
Value *SrcM1 = ConstantInt::get(Src->getType(), 1);
SrcM1 = BinaryOperator::createSub(Src, SrcM1, "", CI);
Src = LowerCTPOP(BinaryOperator::createAnd(NotSrc, SrcM1, "", CI), CI);
CI->replaceAllUsesWith(Src);
break;
}