[DAGCombiner] If ISD::ABS is legal/custom, use it directly instead of canonicalizing first.

Remove an extra canonicalization step if ISD::ABS is going to be used anyway.

Updated x86 abs combine to check that we are lowering from both canonicalizations.

llvm-svn: 302337

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index c2be9f3f058..c77046fdfaf 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -6688,6 +6688,9 @@ SDValue DAGCombiner::visitVSELECT(SDNode *N) {
 
     if (isAbs) {
       EVT VT = LHS.getValueType();
+      if (TLI.isOperationLegalOrCustom(ISD::ABS, VT))
+        return DAG.getNode(ISD::ABS, DL, VT, LHS);
+
       SDValue Shift = DAG.getNode(
           ISD::SRA, DL, VT, LHS,
           DAG.getConstant(VT.getScalarSizeInBits() - 1, DL, VT));