[PATCH] D53744: [SimpleLoopUnswitch] Unswitch by experimental.guard intrinsics

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev created this revision.
mkazantsev added reviewers: asbirlea, chandlerc, fedor.sergeev.

This patch adds support of `llvm.experimental.guard` intrinsics to non-trivial
simple loop unswitching. These intrinsics represent implicit control flow which
has pretty much the same semantics as usual conditional branches. The
algorithm of dealing with them is following:

- Consider guards as unswitching candidates;
- If a guard is considered the best candidate, turn it into a branch;
- Apply normal unswitching algorithm on this branch.

The patch has no compile time effect on code that does not contain any guards.


https://reviews.llvm.org/D53744

Files:
  lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
  test/Transforms/SimpleLoopUnswitch/guards.ll

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