[llvm] [RISCV] Model interleave2 and deinterleave2 costs with Zvzip (PR #225752)

[Pengcheng Wang via llvm-commits]

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@@ -733,6 +733,54 @@ InstructionCost RISCVTTIImpl::getSlideCost(FixedVectorType *Tp,
   return FirstSlideCost + SecondSlideCost + MaskCost;
 }
 
+/// Return the type used to cost vzip.vv, whose LMUL represents the
+/// interleaved destination EMUL. Return std::nullopt if illegal.
+static std::optional<MVT> getZvzipVZIPCostVT(MVT InterleavedVT,
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wangpc-pp wrote:

Make them methods in RISCVTTIImpl? Then we don't need to pass RISCVSubtarget and RISCVTargetLowering.

https://github.com/llvm/llvm-project/pull/225752