[all-commits] [llvm/llvm-project] 300870: [VectorCombine] Switch to using a worklist.

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 300870a95c22fde840862cf57d82adba3e5bd633
      https://github.com/llvm/llvm-project/commit/300870a95c22fde840862cf57d82adba3e5bd633
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2021-09-22 (Wed, 22 Sep 2021)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/VectorCombine.cpp
    M llvm/test/Transforms/PhaseOrdering/AArch64/matrix-extract-insert.ll
    M llvm/test/Transforms/VectorCombine/AArch64/load-extract-insert-store-scalarization.ll
    M llvm/test/Transforms/VectorCombine/X86/extract-binop-inseltpoison.ll
    M llvm/test/Transforms/VectorCombine/X86/extract-binop.ll
    M llvm/test/Transforms/VectorCombine/load-insert-store.ll

  Log Message:
  -----------
  [VectorCombine] Switch to using a worklist.

This patch updates VectorCombine to use a worklist to allow iterative
simplifications where a combine enables other combines.

Suggested in D100302.

The main use case at the moment is foldSingleElementStore and
scalarizeLoadExtract working together to improve scalarization.

Note that we now also do not run SimplifyInstructionsInBlock on the
whole function if there have been changes. This means we fail to
remove/simplify instructions not related to any of the vector combines.
IMO this is fine, as simplifying the whole function seems more like a
workaround for not tracking the changed instructions.

Compile-time impact looks neutral:
NewPM-O3: +0.02%
NewPM-ReleaseThinLTO: -0.00%
NewPM-ReleaseLTO-g: -0.02%

http://llvm-compile-time-tracker.com/compare.php?from=52832cd917af00e2b9c6a9d1476ba79754dcabff&to=e66520a4637290550a945d528e3e59573485dd40&stat=instructions

Reviewed By: spatel, lebedev.ri

Differential Revision: https://reviews.llvm.org/D110171