[all-commits] [llvm/llvm-project] 856cc6: [InstCombine] canonicalize bitcast after insertele...

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  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 856cc60bc1ad07b5cba1ab81160c1c3ef8ff4c23
      https://github.com/llvm/llvm-project/commit/856cc60bc1ad07b5cba1ab81160c1c3ef8ff4c23
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2020-05-10 (Sun, 10 May 2020)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
    M llvm/test/Transforms/InstCombine/bitcast-vec-canon.ll

  Log Message:
  -----------
  [InstCombine] canonicalize bitcast after insertelement into undef

We have a transform in the opposite direction only for the x86 MMX type,
Other types are not handled either way before this patch.

The motivating case from PR45748:
https://bugs.llvm.org/show_bug.cgi?id=45748
...is the last test diff. In that example, we are triggering an existing
bitcast transform, so we reduce the number of casts, and that should give
us the ideal x86 codegen.

Differential Revision: https://reviews.llvm.org/D79171