[all-commits] [llvm/llvm-project] 0c62d8: [VPlan] Record estimated branch probabilities on V...

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0c62d834abff9b180def1b32d3cf9c225d504994
      https://github.com/llvm/llvm-project/commit/0c62d834abff9b180def1b32d3cf9c225d504994
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2026-09-09 (Wed, 09 Sep 2026)

  Changed paths:
    M llvm/include/llvm/Transforms/Vectorize/LoopVectorize.h
    M llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/lib/Transforms/Vectorize/VPlan.cpp
    M llvm/lib/Transforms/Vectorize/VPlan.h
    M llvm/lib/Transforms/Vectorize/VPlanConstruction.cpp
    M llvm/lib/Transforms/Vectorize/VPlanHelpers.h
    M llvm/lib/Transforms/Vectorize/VPlanPredicator.cpp
    M llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
    M llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
    M llvm/lib/Transforms/Vectorize/VPlanTransforms.h
    M llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp
    M llvm/lib/Transforms/Vectorize/VPlanUtils.cpp
    M llvm/lib/Transforms/Vectorize/VPlanUtils.h
    M llvm/test/Transforms/LoopVectorize/VPlan/execution-frequencies-match-bfi.ll
    M llvm/test/Transforms/LoopVectorize/replicate-region-cost-probability.ll
    M llvm/unittests/Transforms/Vectorize/VPlanTestBase.h

  Log Message:
  -----------
  [VPlan] Record estimated branch probabilities on VPlan0 for cost modeling (#216172)

Update execution frequency/probability tracking in VPlan to also include
estimates from BFI, and use the information in VPlan for VPlan-based
cost computations, removing another remaining IR-based lookup.

We need to differentiate between estimated and concrete profile
information when annotating branches with information from BFI (using
custom !vplan.prof.estimated metadata instead of !prof) and track if a
computed frequency contains any estimates using an extra bool which is
also encoded in the metadata (so we do not synthesize !prof
for such frequencies during codegen).

The new code should only request BFI if needed, and compile-time impact
should be in the noise:

https://llvm-compile-time-tracker.com/compare.php?from=8436dd4a2bfe57d0b3fb6c9c11c69d75c1d1bccb&to=4d60694fed5e5765d4f5a2a72aac7b8674e512e2&stat=instructions:u

PR: https://github.com/llvm/llvm-project/pull/216172



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