[PATCH] D83833: [GISel] Add new GISel combiners for G_SELECT

[Michael Kitzan via Phabricator via llvm-commits]

mkitzan created this revision.
mkitzan added reviewers: aditya_nandakumar, dsanders, arsenm, aemerson, paquette.
mkitzan added a project: LLVM.
Herald added subscribers: llvm-commits, hiraditya, kristof.beyls, wdng.

Patch adds three new `GICombinerRule`s for `G_SELECT`. The rules include: combining selects with `undef` comparisons into their first selectee value, combining selects with one more `undef` selectee values into a non-`undef` selectee value (if one's available, otherwise combine into `undef`), and to combine away selects with constant comparisons. Patch additionally adds a new combiner test for the AArch64 target to test these new `G_SELECT` combiner rules and the existing `select_same_val` combiner rule.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D83833

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/combine-select.mir

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