[llvm] [RISCV] Add DAG combine to convert (iN reduce.add (zext (vXi1 A to vXiN)) into vcpop.m (PR #127497)

[Craig Topper via llvm-commits]

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@@ -18100,25 +18100,38 @@ static SDValue combineTruncToVnclip(SDNode *N, SelectionDAG &DAG,
 //   (iX ctpop (bitcast (vXi1 A)))
 // ->
 //   (zext (vcpop.m (nxvYi1 (insert_subvec (vXi1 A)))))
+// and
+//   (iN reduce.add (zext (vXi1 A to vXiN))
+// ->
+//   (zext (vcpop.m (nxvYi1 (insert_subvec (vXi1 A)))))
 // FIXME: It's complicated to match all the variations of this after type
 // legalization so we only handle the pre-type legalization pattern, but that
 // requires the fixed vector type to be legal.
-static SDValue combineScalarCTPOPToVCPOP(SDNode *N, SelectionDAG &DAG,
-                                         const RISCVSubtarget &Subtarget) {
+static SDValue combineVCPOP(SDNode *N, SelectionDAG &DAG,
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topperc wrote:

combineVCPOP -> combineToVCPOP

https://github.com/llvm/llvm-project/pull/127497