[llvm] [LV] Factor costInterleaveGatherScatter (NFC) (PR #215857)

[Florian Hahn via llvm-commits]

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@@ -2400,6 +2456,13 @@ bool LoopVectorizationCostModel::isLegalMaskedLoadOrStore(
                                          getLoadStoreAddressSpace(I));
 }
 
+bool LoopVectorizationCostModel::isLegalGatherOrScatter(Instruction *I,
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fhahn wrote:

Hmm, AFAICT the follow-up patch decision logic is completely driven by the legacy cost model decision?

https://github.com/llvm/llvm-project/pull/215857