[all-commits] [llvm/llvm-project] 90d824: [SCEV] Use loop guards when checking that RHS >= S...

[Nikita Popov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 90d82412ea2103fe086a968c29e8ba4ea899381e
      https://github.com/llvm/llvm-project/commit/90d82412ea2103fe086a968c29e8ba4ea899381e
  Author: Nikita Popov <npopov at redhat.com>
  Date:   2023-12-12 (Tue, 12 Dec 2023)

  Changed paths:
    M llvm/lib/Analysis/ScalarEvolution.cpp
    M llvm/test/Analysis/ScalarEvolution/trip-count.ll

  Log Message:
  -----------
  [SCEV] Use loop guards when checking that RHS >= Start (#75039)

Loop guards tend to provide better results when it comes to reasoning
about ranges than isLoopEntryGuardedByCond(). See the test change for
the motivating case.

I have retained both the loop guard check and the implied cond based
check for now, though the latter only seems to impact a single test and
only via side effects (nowrap flag calculation) at that.