[PATCH] D97397: [InstCombine] Add a combine for a shuffle of similar bitcasts

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added a comment.

I'd like to see some test improvements:

1. There are no tests with extra uses on bitcasts
2. There are no tests with something like

  %xb = bitcast <2 x half> %x to <2 x i16>
  %yb = bitcast <2 x bfloat> %y to <2 x i16>
  %r = shufflevector <2 x i16> %xb, <2 x i16> %yb, <4 x i16> <i16 3, i16 2, i16 1, i16 0>

I suspect this will miscompile?

3. Some tests have unneeded stuff. They should only contain 2 `bitcast`s and a `shufflevector` (and a `ret`), nothing more.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D97397/new/

https://reviews.llvm.org/D97397