[llvm] [AArch64][SVE2p1] Allow more uses of mask in performActiveLaneMaskCombine (PR #159360)

[Paul Walker via llvm-commits]

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@@ -18820,32 +18826,39 @@ performActiveLaneMaskCombine(SDNode *N, TargetLowering::DAGCombinerInfo &DCI,
 
   SDValue Idx = N->getOperand(0);
   SDValue TC = N->getOperand(1);
-  EVT OpVT = Idx.getValueType();
-  if (OpVT != MVT::i64) {
+  if (Idx.getValueType() != MVT::i64) {
     Idx = DAG.getNode(ISD::ZERO_EXTEND, DL, MVT::i64, Idx);
     TC = DAG.getNode(ISD::ZERO_EXTEND, DL, MVT::i64, TC);
   }
 
   // Create the whilelo_x2 intrinsics from each pair of extracts
   EVT ExtVT = Extracts[0]->getValueType(0);
+  EVT DoubleExtVT = ExtVT.getDoubleNumVectorElementsVT(*DAG.getContext());
   auto R =
       DAG.getNode(ISD::INTRINSIC_WO_CHAIN, DL, {ExtVT, ExtVT}, {ID, Idx, TC});
   DCI.CombineTo(Extracts[0], R.getValue(0));
   DCI.CombineTo(Extracts[1], R.getValue(1));
+  SmallVector<SDValue> Concats = {DAG.getNode(
+      ISD::CONCAT_VECTORS, DL, DoubleExtVT, {R.getValue(0), R.getValue(1)})};
 
-  if (NumUses == 2)
-    return SDValue(N, 0);
+  if (NumExts == 2) {
+    assert(N->getValueType(0) == DoubleExtVT);
+    return Concats[0];
+  }
 
-  auto Elts = DAG.getElementCount(DL, OpVT, ExtVT.getVectorElementCount() * 2);
-  for (unsigned I = 2; I < NumUses; I += 2) {
+  auto Elts =
+      DAG.getElementCount(DL, MVT::i64, ExtVT.getVectorElementCount() * 2);
+  for (unsigned I = 2; I < NumExts; I += 2) {
     // After the first whilelo_x2, we need to increment the starting value.
-    Idx = DAG.getNode(ISD::UADDSAT, DL, OpVT, Idx, Elts);
+    Idx = DAG.getNode(ISD::UADDSAT, DL, MVT::i64, Idx, Elts);
     R = DAG.getNode(ISD::INTRINSIC_WO_CHAIN, DL, {ExtVT, ExtVT}, {ID, Idx, TC});
     DCI.CombineTo(Extracts[I], R.getValue(0));
     DCI.CombineTo(Extracts[I + 1], R.getValue(1));
+    Concats.push_back(DAG.getNode(ISD::CONCAT_VECTORS, DL, DoubleExtVT,
+                                  {R.getValue(0), R.getValue(1)}));
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paulwalker-arm wrote:

Is wrapping the operands in {} necessary?

https://github.com/llvm/llvm-project/pull/159360