[llvm] [CostModel][AArch64] Make extractelement, with fmul user, free whenev… (PR #111479)

[Sushant Gokhale via llvm-commits]

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@@ -3145,12 +3153,16 @@ InstructionCost AArch64TTIImpl::getCFInstrCost(unsigned Opcode,
   return 0;
 }
 
-InstructionCost AArch64TTIImpl::getVectorInstrCostHelper(const Instruction *I,
-                                                         Type *Val,
-                                                         unsigned Index,
-                                                         bool HasRealUse) {
+InstructionCost AArch64TTIImpl::getVectorInstrCostHelper(
+    std::variant<const Instruction *, const unsigned> InstOrOpcode, Type *Val,
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sushgokh wrote:

1. Sometimes Instruction itself is passed to this API to get more information. So, `const Instruction *I` has to be one of the arguments
2. The thinking behind using single variable for Instruction and Opcode(using variant) is Instruction and Opcode is somewhat related but we never pass both unless its required in future.

https://github.com/llvm/llvm-project/pull/111479