[PATCH] D92317: [LV] ExtractValue instruction costs

Mon Nov 30 11:33:14 PST 2020

fhahn added a comment.

In D92317#2423288 <https://reviews.llvm.org/D92317#2423288>, @SjoerdMeijer wrote:

> Decided to use `TTI.getInstructionCost` because getVectorInstrCost doesn't work here; it's an aggregate type, not really a vector.
> That means the cost for a ExtractValue will be Free now, which I think is actually more accurate (than 1, and also the original 4).
> I haven't added InsertValue yet, because that is e.g. not supported by getInstructionCost as it seems a little bit of a different beast.

SGTM, I was thinking about *insertelement*... Sorry about that.

================
Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:6858
+    // Assume we need 1 instruction to extract a value from a vector.
+    return 1;
   default:
----------------
SjoerdMeijer wrote:
> fhahn wrote:
> > Better to use `TTI.getVectorInstrCost`? And perhaps also handle `InsertValue`?
> Yeah, cheers, will look/do that.
Should this also handle `InsertValue` for completeness?

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https://reviews.llvm.org/D92317