[llvm] [GlobalIsel] Push cast through build vector (PR #104634)

[Dhruv Chawla via llvm-commits]

Thorsten =?utf-8?q?Schütt?= <schuett at gmail.com>
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In-Reply-To: <llvm.org/llvm/llvm-project/pull/104634 at github.com>


dc03-work wrote:

> I believe what we found was that if there were two truncs it would be OK to leave it scalarized, but for 4+ the vector trunc is generally better so long as the inputs come from a vector.

@tschuett I think it would be a good idea to try this - by bailing out if the buildvector has >= 4 sources. That should help mitigate the more serious regressions that are occuring.


https://github.com/llvm/llvm-project/pull/104634