[llvm] [DAGCombiner][VP] Add DAGCombine for VP_MUL (PR #80105)

[Shao-Ce SUN via llvm-commits]

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@@ -4356,11 +4357,13 @@ SDValue DAGCombiner::visitMULFIX(SDNode *N) {
   return SDValue();
 }
 
-SDValue DAGCombiner::visitMUL(SDNode *N) {
+template <class MatchContextClass> SDValue DAGCombiner::visitMUL(SDNode *N) {
   SDValue N0 = N->getOperand(0);
   SDValue N1 = N->getOperand(1);
   EVT VT = N0.getValueType();
   SDLoc DL(N);
+  bool IsVP = ISD::isVPOpcode(N->getOpcode());
+  MatchContextClass matcher(DAG, TLI, N);
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sunshaoce wrote:

While `matcher` is used in functions like `visitFMA`, I still believe using `Matcher` is better to avoid the clang-tidy warning about `Invalid case style for variable 'matcher' (fix available) clang-tidy`

https://github.com/llvm/llvm-project/pull/80105