fix an off-by-one bug that caused a crash analyzing
ashr's with huge shift amounts, PR8896
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122814 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 6f58afe..e2d7e92 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -337,7 +337,7 @@
// (ashr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
// Compute the new bits that are at the top now.
- uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
+ uint64_t ShiftAmt = SA->getLimitedValue(BitWidth-1);
// Signed shift right.
APInt Mask2(Mask.shl(ShiftAmt));