[PATCH] D132483: [AMDGPU][GlobalISel] Improve BFI Pattern Matching

[Jay Foad via Phabricator via llvm-commits]

foad added a comment.

My gut feeling is that this is the wrong approach, because it will convert SALU to VALU operations regardless of whether they can actually be matched by some larger VALU pattern. This is bad for all sorts of reasons especially on GFX10+: latency, occupancy, power consumption.

Instead I think the pattern matching for instructions like BFI needs to be able to look through cross-regbank copies. There has been some discussion in the past about this. Please read through https://discourse.llvm.org/t/globalisel-cross-bank-constant-propagation/57927 for a start.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D132483/new/

https://reviews.llvm.org/D132483