Fold the full generality of (any_extend (truncate x))
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30514 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 4e3b572..bcbac95 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1858,9 +1858,15 @@
N0.getOpcode() == ISD::SIGN_EXTEND)
return DAG.getNode(N0.getOpcode(), VT, N0.getOperand(0));
- // fold (aext (truncate x)) -> x iff x size == zext size.
- if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT)
- return N0.getOperand(0);
+ // fold (aext (truncate x))
+ if (N0.getOpcode() == ISD::TRUNCATE) {
+ SDOperand TruncOp = N0.getOperand(0);
+ if (TruncOp.getValueType() == VT)
+ return TruncOp; // x iff x size == zext size.
+ if (TruncOp.getValueType() > VT)
+ return DAG.getNode(ISD::TRUNCATE, VT, TruncOp);
+ return DAG.getNode(ISD::ANY_EXTEND, VT, TruncOp);
+ }
// fold (aext (load x)) -> (aext (truncate (extload x)))
if (N0.getOpcode() == ISD::LOAD && N0.hasOneUse() &&
(!AfterLegalize||TLI.isOperationLegal(ISD::EXTLOAD, N0.getValueType()))) {