ComputeMaskedBits: sub falls through to add, and sub doesn't have the same overflow semantics as add.
Should fix the selfhost failures that started with r127463.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127465 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 33fb1e8..6c33d2d 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -431,7 +431,8 @@
}
// Are we still trying to solve for the sign bit?
- if (Mask.isNegative() && !KnownZero.isNegative() && !KnownOne.isNegative()){
+ if (I->getOpcode() == Instruction::Add &&
+ Mask.isNegative() && !KnownZero.isNegative() && !KnownOne.isNegative()){
OverflowingBinaryOperator *OBO = cast<OverflowingBinaryOperator>(I);
if (OBO->hasNoSignedWrap()) {
// Adding two positive numbers can't wrap into negative ...