PR9346: Prevent SimplifyDemandedBits from incorrectly introducing
INT_MIN % -1.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127306 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index b12d4c3..6e727ce 100644
--- a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -684,6 +684,10 @@
break;
case Instruction::SRem:
if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
+ // X % -1 demands all the bits because we don't want to introduce
+ // INT_MIN % -1 (== undef) by accident.
+ if (Rem->isAllOnesValue())
+ break;
APInt RA = Rem->getValue().abs();
if (RA.isPowerOf2()) {
if (DemandedMask.ult(RA)) // srem won't affect demanded bits