[PATCH] D82227: SLP: honor requested max vector size merging PHIs

Wed Nov 11 10:16:42 PST 2020

rampitec added a comment.

In D82227#2389212 <https://reviews.llvm.org/D82227#2389212>, @jonpa wrote:

> I am afraid that this patch actually has a bad impact on performance on SystemZ, and unfortunately this was not known until now. It would be very appreciated if we could rework this and get back the old behaviour on SystemZ somehow...
>
> See https://bugs.llvm.org/show_bug.cgi?id=48155

I believe if a target wants to have wider vectors it needs to increase the size returned from its TTIImpl::getRegisterBitWidth(). Can you try increasing a return from SystemZTTIImpl::getRegisterBitWidth()?

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https://reviews.llvm.org/D82227