[PATCH] D90445: [SLP] Make SLPVectorizer to use `llvm.masked.gather` intrinsic

[Anton Afanasyev via Phabricator via llvm-commits]

anton-afanasyev added inline comments.


================
Comment at: llvm/test/Transforms/SLPVectorizer/X86/pr47629.ll:17
+; CHECK-NEXT:    store <4 x i32> [[TMP11]], <4 x i32>* [[TMP12]], align 4
 ; CHECK-NEXT:    ret void
 ;
----------------
RKSimon wrote:
> anton-afanasyev wrote:
> > anton-afanasyev wrote:
> > > RKSimon wrote:
> > > > This doesn't look great in the final codegen: https://gcc.godbolt.org/z/vE9Yoe
> > > > 
> > > > Which suggests either the costs aren't correct or we're not correctly including the cost of something - the buildvector of the pointers? are we missing getelementptr vectorization?
> > > Oops, thanks, it looks I've missed the buildvector cost.
> > Hmm, investigated this: no, I was wrong, the calculated cost is correct (`insertelemets`s for gather instr are compesated by `insertelement`s for buildvector). Further investigating this... Looks like codegen issue more.
> Hmm - does the X86 TTI handle buildvectors of pointers costs or does it fallback to the generic implementation (which is almost certainly lower)?
Despite of codegen output for Skylake looking complicated I believe it's still more optimized, since the `gather` is cheaper than four `load`s from memory, isn't it?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D90445/new/

https://reviews.llvm.org/D90445