RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2024-10-19 11:02:59 +02:00
Code Issues Projects Releases Wiki Activity

fix a potential overflow issue Eli pointed out.

Browse Source 
llvm-svn: 94336
This commit is contained in:
Chris Lattner 2010-01-23 23:31:46 +00:00
parent f9a681fb61
commit b9e618553f
1 changed files with 3 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
lib/Transforms/InstCombine/InstCombineShifts.cpp
View File

@ -394,16 +394,16 @@ Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1))
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Op0)) {
unsigned BitWidth = Op0->getType()->getScalarSizeInBits();
// ctlz.i32(x)>>5 --> zext(x == 0)
// cttz.i32(x)>>5 --> zext(x == 0)
// ctpop.i32(x)>>5 --> zext(x == -1)
if ((II->getIntrinsicID() == Intrinsic::ctlz ||
II->getIntrinsicID() == Intrinsic::cttz ||
II->getIntrinsicID() == Intrinsic::ctpop) &&
(1ULL << Op1C->getZExtValue()) ==
Op0->getType()->getScalarSizeInBits()) {
isPowerOf2_32(BitWidth) && Log2_32(BitWidth) == Op1C->getZExtValue()){
bool isCtPop = II->getIntrinsicID() == Intrinsic::ctpop;
Constant *RHS = ConstantInt::getSigned(Op0->getType(), isCtPop ? -1 : 0);
Constant *RHS = ConstantInt::getSigned(Op0->getType(), isCtPop ? -1:0);
Value *Cmp = Builder->CreateICmpEQ(II->getOperand(1), RHS);
return new ZExtInst(Cmp, II->getType());
}