Teach DAG combine to handle vector add/sub with vectors of all 0s.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169727 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 6a43337..e774c13 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1381,6 +1381,12 @@
if (VT.isVector()) {
SDValue FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.getNode()) return FoldedVOp;
+
+ // fold (add x, 0) -> x, vector edition
+ if (ISD::isBuildVectorAllZeros(N1.getNode()))
+ return N0;
+ if (ISD::isBuildVectorAllZeros(N0.getNode()))
+ return N1;
}
// fold (add x, undef) -> undef
@@ -1624,6 +1630,10 @@
if (VT.isVector()) {
SDValue FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.getNode()) return FoldedVOp;
+
+ // fold (sub x, 0) -> x, vector edition
+ if (ISD::isBuildVectorAllZeros(N1.getNode()))
+ return N0;
}
// fold (sub x, x) -> 0