fix a bug where the bswap matcher could match a case involving
ashr. It should only apply to lshr.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57089 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 4f48971..95ed49d 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -3912,9 +3912,12 @@
if (I->getOpcode() == Instruction::Shl) {
// X << 24 defines the top byte with the lowest of the input bytes.
DestNo = ByteValues.size()-1;
- } else {
+ } else if (I->getOpcode() == Instruction::LShr) {
// X >>u 24 defines the low byte with the highest of the input bytes.
DestNo = 0;
+ } else {
+ // Arithmetic shift right may have the top bits set.
+ return true;
}
// If the destination byte value is already defined, the values are or'd