[all-commits] [llvm/llvm-project] 677048: [SCEV] Track backedge taken count users (NFCI)

Nikita Popov via All-commits all-commits at lists.llvm.org
Wed Dec 1 01:17:04 PST 2021

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 67704801c679a59c552dfade92a3d7c53979e2c8
  Author: Nikita Popov <nikita.ppv at gmail.com>
  Date:   2021-12-01 (Wed, 01 Dec 2021)

  Changed paths:
    M llvm/include/llvm/Analysis/ScalarEvolution.h
    M llvm/lib/Analysis/ScalarEvolution.cpp

  Log Message:
  [SCEV] Track backedge taken count users (NFCI)

Track which SCEVs are used as ExactNotTaken counts in
BackedgeTakenInfo structures, so we can directly determine which
loops need to be invalidated, rather than iterating over all BECounts.

This gives a small compile-time improvement on average, but the
motivation here is more to ensure there are no degenerate cases,
if the number of backedge taken counts is large.

Differential Revision: https://reviews.llvm.org/D114784

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