avoid constructing out of range shift amounts.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22230 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 76f11a5..321b032 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -2511,8 +2511,10 @@
if (!CanFold) {
// To test for the bad case of the signed shr, see if any
// of the bits shifted in could be tested after the mask.
- Constant *OShAmt = ConstantUInt::get(Type::UByteTy,
- Ty->getPrimitiveSizeInBits()-ShAmt->getValue());
+ int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
+ if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
+
+ Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
Constant *ShVal =
ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())