[PATCH] D76983: [InstCombine] Transform extractelement-trunc -> bitcast-extractelement

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

In D76983#1955540 <https://reviews.llvm.org/D76983#1955540>, @lebedev.ri wrote:

> > Ie, is there consensus that forming a size-changing vector cast from a shuffle is canonical?
>
> I would have guessed it is, yes.


Agree - the trunc is better for analysis, and a quick check of various backends says we do worse at codegen of the shuffle than the trunc, so that's more likely to be the expected form.
And not sure if it counts for anything, but the trunc is the more human-readable form (vs. translating shuffle indexes that depend on endian).
I'll draft a patch.


Repository:
  rG LLVM Github Monorepo

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