[PATCH] D133300: [InstCombine] Matrix multiplication negation optimisation

Thu Sep 8 08:42:32 PDT 2022

zjaffal added a comment.

In D133300#3774699 <https://reviews.llvm.org/D133300#3774699>, @radford wrote:

> In D133300#3771911 <https://reviews.llvm.org/D133300#3771911>, @thegameg wrote:
>
>> Are we looking to also support `-(A * B) -> -A * B` with the negation on the cheapest operand? (might need to check what the required fast math flags are)
>
> We should.  In particular, there three places for the negation to go: `-A * B = A * -B = -(A * B)` and any one of the three might be smaller.

Yes I am not covering this case. I can add a test case for it and then introduce another patch for it

Repository:
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https://reviews.llvm.org/D133300