[PATCH] D107344: [SLP]Do not emit extra shuffle for insertelements vectorization.

[Steven Johnson via Phabricator via llvm-commits]

srj added a comment.

In D107344#2925918 <https://reviews.llvm.org/D107344#2925918>, @ABataev wrote:

> In D107344#2925891 <https://reviews.llvm.org/D107344#2925891>, @srj wrote:
>
>> This appears to have injected a failure into Halide codegen; I'll be providing a repro case shortly.
>
> Thanks for the report, waiting for the repro.

Still trying to get something self-contained for  you, but the difference in codegen is something like:

before:

  %193 = shufflevector <2 x double> %179, <2 x double> poison, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef>
  ...
  %200 = insertelement <4 x double> %193, double 1.000000e+02, i32 3
  %201 = insertelement <4 x double> %200, double %184, i32 2

after:

  %193 = shufflevector <2 x double> %179, <2 x double> poison, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef>
  ...
  %200 = insertelement <4 x double> %193, double %184, i32 2


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D107344/new/

https://reviews.llvm.org/D107344