[PATCH] D39906: [InstCombine] Allowing GEP Instructions with loop Invariant operands to combine

[Sebastian Pop via Phabricator via llvm-commits]

sebpop added a comment.

In https://reviews.llvm.org/D39906#1031961, @efriedma wrote:

> The 175.vpr result looks bad.


That's noise, I just reran that benchmark and the 1% slowdown is within the noise level: in the new run vpr shows a speedup of 1.47%.

> I'm still not convinced this is the right approach; if you look at the testcase as a reassociation problem, you can optimize it without duplicating code.

Could you please explain how you want to optimize this sequence?
I also don't see where "duplicating code" comes from.

Also looking at the AVX512 example that needed to be amended, you see that
this pattern matches at quite some spots in there, and that it transforms two geps
into only one.


https://reviews.llvm.org/D39906