Optimize concat_vectors(X, undef) -> scalar_to_vector(X).
This optimization is not SSE specific so I am moving it to DAGco.
The new scalar_to_vector dag node exposed a missing pattern in the AArch64 target that I needed to add.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193393 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 0179cf1..3cbd6d0 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -9836,8 +9836,35 @@
return N->getOperand(0);
// Check if all of the operands are undefs.
+ EVT VT = N->getValueType(0);
if (ISD::allOperandsUndef(N))
- return DAG.getUNDEF(N->getValueType(0));
+ return DAG.getUNDEF(VT);
+
+ // Optimize concat_vectors where one of the vectors is undef.
+ if (N->getNumOperands() == 2 &&
+ N->getOperand(1)->getOpcode() == ISD::UNDEF) {
+ SDValue In = N->getOperand(0);
+ assert(In->getValueType(0).isVector() && "Must concat vectors");
+
+ // Transform: concat_vectors(scalar, undef) -> scalar_to_vector(sclr).
+ if (In->getOpcode() == ISD::BITCAST &&
+ !In->getOperand(0)->getValueType(0).isVector()) {
+ SDValue Scalar = In->getOperand(0);
+ EVT SclTy = Scalar->getValueType(0);
+
+ if (!SclTy.isFloatingPoint() && !SclTy.isInteger())
+ return SDValue();
+
+ EVT NVT = EVT::getVectorVT(*DAG.getContext(), SclTy,
+ VT.getSizeInBits() / SclTy.getSizeInBits());
+ if (!TLI.isTypeLegal(NVT) || !TLI.isTypeLegal(Scalar.getValueType()))
+ return SDValue();
+
+ SDLoc dl = SDLoc(N);
+ SDValue Res = DAG.getNode(ISD::SCALAR_TO_VECTOR, dl, NVT, Scalar);
+ return DAG.getNode(ISD::BITCAST, dl, VT, Res);
+ }
+ }
// Type legalization of vectors and DAG canonicalization of SHUFFLE_VECTOR
// nodes often generate nop CONCAT_VECTOR nodes.