Add support for constant expr shifts

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9735 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 0 deletions

diff --git a/lib/VMCore/Constants.cpp b/lib/VMCore/Constants.cpp
index bc1e9d2c1c..28cc9d24e0 100644
--- a/lib/VMCore/Constants.cpp
+++ b/lib/VMCore/Constants.cpp
@@ -493,6 +493,13 @@ void ConstantExpr::replaceUsesOfWithOnConstant(Value *From, Value *ToV,
   } else if (getOpcode() == Instruction::Cast) {
     assert(getOperand(0) == From && "Cast only has one use!");
     Replacement = ConstantExpr::getCast(To, getType());
+  } else if (getOpcode() == Instruction::Shl ||
+             getOpcode() == Instruction::Shr) {
+    Constant *C1 = getOperand(0);
+    Constant *C2 = getOperand(1);
+    if (C1 == From) C1 = To;
+    if (C2 == From) C2 = To;
+    Replacement = ConstantExpr::getShift(getOpcode(), C1, C2);
   } else if (getNumOperands() == 2) {
     Constant *C1 = getOperand(0);
     Constant *C2 = getOperand(1);