fix PR7589: In brief:
gep P, (zext x) != gep P, (sext x)
DecomposeGEPExpression was getting this wrong, confusing
basicaa.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111352 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index b4c9884..cf20e07 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -1018,9 +1018,9 @@
}
}
- // Since clients don't care about the high bits of the value, just scales and
- // offsets, we can look through extensions.
- if (isa<SExtInst>(V) || isa<ZExtInst>(V)) {
+ // Since GEP indices are sign extended anyway, we don't care about the high
+ // bits of a sign extended value - just scales and offsets.
+ if (isa<SExtInst>(V)) {
Value *CastOp = cast<CastInst>(V)->getOperand(0);
unsigned OldWidth = Scale.getBitWidth();
unsigned SmallWidth = CastOp->getType()->getPrimitiveSizeInBits();