Add support for constant expr shifts


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9735 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Bytecode/Reader/ConstantReader.cpp b/lib/Bytecode/Reader/ConstantReader.cpp
index 097bdbe..00f44b3 100644
--- a/lib/Bytecode/Reader/ConstantReader.cpp
+++ b/lib/Bytecode/Reader/ConstantReader.cpp
@@ -182,6 +182,8 @@
     } else if (Opcode == Instruction::GetElementPtr) { // GetElementPtr
       std::vector<Constant*> IdxList(ArgVec.begin()+1, ArgVec.end());
       return ConstantExpr::getGetElementPtr(ArgVec[0], IdxList);
+    } else if (Opcode == Instruction::Shl || Opcode == Instruction::Shr) {
+      return ConstantExpr::getShift(Opcode, ArgVec[0], ArgVec[1]);
     } else {                            // All other 2-operand expressions
       return ConstantExpr::get(Opcode, ArgVec[0], ArgVec[1]);
     }
diff --git a/lib/VMCore/Constants.cpp b/lib/VMCore/Constants.cpp
index bc1e9d2..28cc9d2 100644
--- a/lib/VMCore/Constants.cpp
+++ b/lib/VMCore/Constants.cpp
@@ -493,6 +493,13 @@
   } 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);