[llvm] [AArch64] Increase scatter overhead on Neoverse-V2 (PR #101296)

[Madhur Amilkanthwar via llvm-commits]

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@@ -3424,7 +3424,15 @@ InstructionCost AArch64TTIImpl::getGatherScatterOpCost(
   // Add on an overhead cost for using gathers/scatters.
   // TODO: At the moment this is applied unilaterally for all CPUs, but at some
   // point we may want a per-CPU overhead.
-  MemOpCost *= getSVEGatherScatterOverhead(Opcode);
+  unsigned OpCost = 1;
+  if (ST->getProcFamily() == AArch64Subtarget::NeoverseV2) {
+     // Specialize overhead of scatter instructions on Neoverse-V2
+    if (Opcode == Instruction::Store)
+      OpCost = 13;
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madhur13490 wrote:

I restructed the code a bit.

https://github.com/llvm/llvm-project/pull/101296