Only transform (sext (truncate x)) -> (sextinreg x) if before legalize or
if the target supports the resultant sextinreg
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24632 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index b7f6853..7adfecb 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1547,7 +1547,9 @@
if (N0.getOpcode() == ISD::SEXTLOAD && VT == N0.getValueType())
return N0;
// fold (sext (truncate x)) -> (sextinreg x) iff x size == sext size.
- if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT)
+ if (N0.getOpcode() == ISD::TRUNCATE && N0.getOperand(0).getValueType() == VT&&
+ (!AfterLegalize ||
+ TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG, N0.getValueType())))
return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, N0.getOperand(0),
DAG.getValueType(N0.getValueType()));
// fold (sext (load x)) -> (sextload x)