1 files changed, 9 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index d52b073..b744537 100755
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -1482,6 +1482,15 @@ Constant *llvm::ConstantFoldFPInstOperands(unsigned Opcode, Constant *LHS,
 Constant *llvm::ConstantFoldCastOperand(unsigned Opcode, Constant *C,
                                         Type *DestTy, const DataLayout &DL) {
   assert(Instruction::isCast(Opcode));
+
+  if (auto *CE = dyn_cast<ConstantExpr>(C))
+    if (CE->isCast())
+      if (unsigned NewOp = CastInst::isEliminableCastPair(
+              Instruction::CastOps(CE->getOpcode()),
+              Instruction::CastOps(Opcode), CE->getOperand(0)->getType(),
+              C->getType(), DestTy, &DL))
+        return ConstantFoldCastOperand(NewOp, CE->getOperand(0), DestTy, DL);
+
   switch (Opcode) {
   default:
     llvm_unreachable("Missing case");