LoopRotate: Don't walk the uses of a Constant
LoopRotate wanted to avoid live range interference by looking at the
uses of a Value in the loop latch and seeing if any lied outside of the
loop. We would wrongly perform this operation on Constants.
This fixes PR22337.
llvm-svn: 227171
diff --git a/llvm/lib/Transforms/Scalar/LoopRotation.cpp b/llvm/lib/Transforms/Scalar/LoopRotation.cpp
index c37cd91..02fb80c 100644
--- a/llvm/lib/Transforms/Scalar/LoopRotation.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopRotation.cpp
@@ -229,20 +229,17 @@
case Instruction::Shl:
case Instruction::LShr:
case Instruction::AShr: {
- Value *IVOpnd = nullptr;
- if (isa<ConstantInt>(I->getOperand(0)))
- IVOpnd = I->getOperand(1);
-
- if (isa<ConstantInt>(I->getOperand(1))) {
- if (IVOpnd)
- return false;
-
- IVOpnd = I->getOperand(0);
- }
+ Value *IVOpnd = !isa<Constant>(I->getOperand(0))
+ ? I->getOperand(0)
+ : !isa<Constant>(I->getOperand(1))
+ ? I->getOperand(1)
+ : nullptr;
+ if (!IVOpnd)
+ return false;
// If increment operand is used outside of the loop, this speculation
// could cause extra live range interference.
- if (MultiExitLoop && IVOpnd) {
+ if (MultiExitLoop) {
for (User *UseI : IVOpnd->users()) {
auto *UserInst = cast<Instruction>(UseI);
if (!L->contains(UserInst))