[PATCH] D134982: [X86] Add support for "light" AVX

Mon Oct 10 17:46:21 PDT 2022

craig.topper added a comment.

In D134982#3848311 <https://reviews.llvm.org/D134982#3848311>, @TokarIP wrote:

> In D134982#3828850 <https://reviews.llvm.org/D134982#3828850>, @craig.topper wrote:
>
>> I don’t think -mprefer-vector-width=128 has effect on most instructions. The 256 version was heavily integrated into the type legalization to split operations. I don’t think that was ever done for 128.
>
> -mprefer-vector-width affects vectorizer decision to choose VL. Here is motivating example: https://godbolt.org/z/j8hrP5jhb

Thansk. I had forgotten it was used in X86TTIImpl::getRegisterBitWidth().

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https://reviews.llvm.org/D134982