[PATCH] D90431: [x86] add cost overrides for mul with overflow

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

In D90431#2363926 <https://reviews.llvm.org/D90431#2363926>, @pengfei wrote:

> Do we need to update the vector version cost as well?

Yes, but it will be more complicated because we will need to map operations/sizes to different ISA attributes. I think it is also less likely to see the vector versions of the intrinsics. For example, we can create this intrinsic from instcombine ( InstCombinerImpl::foldUnsignedMultiplicationOverflowCheck() ). But creating a vector version would mean that we had also encountered/created vector integer division.

My underlying motivation for this is that I am cleaning up the basic class cost model implementation of getIntrinsicInstrCost(), and if we don't have this x86 scalar override, there is a potential regression.
So for those reasons, I prefer to defer the vector implementation to follow-up patch(es). I can add a 'TODO' comment here if that is ok.


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