[PATCH] D126056: [InstCombine] [NFC] Move transforms for truncated shifts into narrowBinOp

[Sanjay Patel via Phabricator via llvm-commits]

spatel accepted this revision.
spatel added a comment.
This revision is now accepted and ready to land.

LGTM - but please add a test to verify that we do not create a bug with `shl`.

I think this would have miscompiled with the previous revision of the patch:

  define <2 x i8> @trunc_lshr_trunc(<2 x i64> %a) {
    %b = trunc <2 x i64> %a to <2 x i32>
    %c = shl <2 x i32> %b, <i32 9, i32 7>
    %d = trunc <2 x i32> %c to <2 x i8>
    ret <2 x i8> %d
  }


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D126056/new/

https://reviews.llvm.org/D126056