[PATCH] D123234: [X86] `lowerBuildVectorAsBroadcast()`: with AVX2, allow i64->XMM broadcasts from constant pool

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added a comment.

In D123234#3435927 <https://reviews.llvm.org/D123234#3435927>, @lebedev.ri wrote:

> I see.
> Please confirm my understanding, you are suggesting that we should generalize `*SET0`/`*SETALLONES` pseudo-instructions
> into `MATERIALIZE` pseudo-instruction, with much the same handling of expanding it post-RA (`expandPostRAPseudo()`)?

I'm not sure if we'd want to handle them as pseudos, or have a pass that converts vector constant pool loads into broadcasts/materialization etc. in general. Handling AVX512 broadcast folds just makes it more difficult.

All of this needs to be done in conjunction with the foldMemoryOperand stages, and I haven't investigated it much as to how to deal with it all.


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