[llvm] [SLP] Make getSameOpcode support different instructions if they have same semantics. (PR #112181)

[Alexey Bataev via llvm-commits]

================
@@ -832,8 +832,107 @@ struct InstructionsState {
       : OpValue(OpValue), MainOp(MainOp), AltOp(AltOp) {}
 };
 
+struct InterchangeableInstruction {
+  unsigned Opcode;
+  SmallVector<Value *> Ops;
+  template <class... ArgTypes>
+  InterchangeableInstruction(unsigned Opcode, ArgTypes &&...Args)
+      : Opcode(Opcode), Ops{std::forward<decltype(Args)>(Args)...} {}
+};
+
+bool operator<(const InterchangeableInstruction &LHS,
+               const InterchangeableInstruction &RHS) {
+  return LHS.Opcode < RHS.Opcode;
+}
+
 } // end anonymous namespace
 
+/// \returns a list of interchangeable instructions which \p I can be converted
----------------
alexey-bataev wrote:

```suggestion
/// \returns Sorted by instruction opcode list of interchangeable instructions which \p I can be converted
```

https://github.com/llvm/llvm-project/pull/112181