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

[Alexey Bataev via llvm-commits]

================
@@ -938,18 +1033,54 @@ static InstructionsState getSameOpcode(ArrayRef<Value *> VL,
     if (!isTriviallyVectorizable(BaseID) && BaseMappings.empty())
       return InstructionsState(VL[BaseIndex], nullptr, nullptr);
   }
+  // Currently, this is only used for binary ops.
+  // TODO: support all instructions
+  SmallVector<InterchangeableInstruction> InterchangeableOpcode =
+      getInterchangeableInstruction(cast<Instruction>(VL[BaseIndex]));
+  SmallVector<InterchangeableInstruction> AlternateInterchangeableOpcode;
+  auto UpdateInterchangeableOpcode =
+      [](SmallVector<InterchangeableInstruction> &LHS,
+         ArrayRef<InterchangeableInstruction> RHS) {
+        SmallVector<InterchangeableInstruction> NewInterchangeableOpcode;
+        std::set_intersection(LHS.begin(), LHS.end(), RHS.begin(), RHS.end(),
+                              std::back_inserter(NewInterchangeableOpcode));
+        if (NewInterchangeableOpcode.empty())
+          return false;
+        LHS = std::move(NewInterchangeableOpcode);
+        return true;
----------------
alexey-bataev wrote:

```suggestion
        LHS.swap(NewInterchangeableOpcode);
        return !LHS.empty();
```

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