[all-commits] [llvm/llvm-project] 13107c: [LoopVectorize] Enable more early exit vectorisati...

[David Sherwood via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 13107cb09441dfeab24fcbcae9f4d3ba4cfc2703
      https://github.com/llvm/llvm-project/commit/13107cb09441dfeab24fcbcae9f4d3ba4cfc2703
  Author: David Sherwood <david.sherwood at arm.com>
  Date:   2024-12-18 (Wed, 18 Dec 2024)

  Changed paths:
    M llvm/include/llvm/Transforms/Vectorize/LoopVectorize.h
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/test/Transforms/LoopVectorize/AArch64/simple_early_exit.ll
    M llvm/test/Transforms/LoopVectorize/early_exit_legality.ll
    M llvm/test/Transforms/LoopVectorize/multi_early_exit.ll
    M llvm/test/Transforms/LoopVectorize/multi_early_exit_live_outs.ll
    M llvm/test/Transforms/LoopVectorize/single_early_exit_live_outs.ll
    A llvm/test/Transforms/LoopVectorize/single_early_exit_with_outer_loop.ll

  Log Message:
  -----------
  [LoopVectorize] Enable more early exit vectorisation tests (#117008)

PR #112138 introduced initial support for dispatching to
multiple exit blocks via split middle blocks. This patch
fixes a few issues so that we can enable more tests to use
the new enable-early-exit-vectorization flag. Fixes are:

1. The code to bail out for any loop live-out values happens
too late. This is because collectUsersInExitBlocks ignores
induction variables, which get dealt with in fixupIVUsers.
I've moved the check much earlier in processLoop by looking
for outside users of loop-defined values.
2. We shouldn't yet be interleaving when vectorising loops
with uncountable early exits, since we've not added support
for this yet.
3. Similarly, we also shouldn't be creating vector epilogues.
4. Similarly, we shouldn't enable tail-folding.
5. The existing implementation doesn't yet support loops
that require scalar epilogues, although I plan to add that
as part of PR #88385.
6. The new split middle blocks weren't being added to the
parent loop.



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