[all-commits] [llvm/llvm-project] 20fc29: [LoopVectorizer] Only check register pressure for ...

[Nicholas Guy via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 20fc297ce3c2a2151bf618cf515f2b1981d4821c
      https://github.com/llvm/llvm-project/commit/20fc297ce3c2a2151bf618cf515f2b1981d4821c
  Author: Nicholas Guy <nicholas.guy at arm.com>
  Date:   2025-07-18 (Fri, 18 Jul 2025)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp
    M llvm/lib/Transforms/Vectorize/VPlanAnalysis.h
    A llvm/test/Transforms/LoopVectorize/AArch64/maxbandwidth-regpressure.ll

  Log Message:
  -----------
  [LoopVectorizer] Only check register pressure for VFs that have been enabled via maxBandwidth (#149056)

Currently if MaxBandwidth is enabled, the register pressure is checked
for each VF. This changes that to only perform said check if the VF
would not have otherwise been considered by the LoopVectorizer if
maxBandwidth was not enabled.

Theoretically this allows for higher VFs to be considered than would
otherwise be deemed "safe" (from a regpressure perspective), but more
concretely this reduces the amount of work done at compile-time when
maxBandwidth is enabled.



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