[PATCH] D77105: [GlobalISel] Implement identity transforms for x op x -> x

[Jessica Paquette via Phabricator via llvm-commits]

paquette created this revision.
paquette added reviewers: aemerson, arsenm.
Herald added subscribers: danielkiss, volkan, hiraditya, kristof.beyls, rovka, wdng.

When we have

  a = G_OR x, x

or

  b = G_AND y, y

We can drop the `G_OR`/`G_AND` and just use `x`/`y` respectively.

Also update arm64-fallback.ll because there was an `or` in there which hits this transformation.


https://reviews.llvm.org/D77105

Files:
  llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
  llvm/include/llvm/Target/GlobalISel/Combine.td
  llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
  llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
  llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-binop-same-val.mir

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