[llvm] [DAGCombine] Count leading ones: refine post DAG/Type Legalisation if promotion (PR #102877)

[Min-Yih Hsu via llvm-commits]

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@@ -47,6 +47,8 @@ class BasicMatchContext {
   bool match(SDValue N, unsigned Opcode) const {
     return N->getOpcode() == Opcode;
   }
+
+  static constexpr bool IsVP = false;
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mshockwave wrote:

have you explored the ideas of abstracting the number of operands instead? Specifically, having a match context to implement its own version of `unsigned getNumOperands(SDValue N)` (or something similar)?

https://github.com/llvm/llvm-project/pull/102877