[all-commits] [llvm/llvm-project] 078899: [SimplifyCFG] Allow SimplifyCFG hoisting to skip o...

[Momchil Velikov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 078899cd64cd2fb787c2c5356e16dd818ee3ad23
      https://github.com/llvm/llvm-project/commit/078899cd64cd2fb787c2c5356e16dd818ee3ad23
  Author: Momchil Velikov <momchil.velikov at arm.com>
  Date:   2022-09-05 (Mon, 05 Sep 2022)

  Changed paths:
    M llvm/lib/Transforms/Utils/SimplifyCFG.cpp
    A llvm/test/Transforms/SimplifyCFG/hoist-common-skip-limit.ll
    A llvm/test/Transforms/SimplifyCFG/hoist-common-skip.ll

  Log Message:
  -----------
  [SimplifyCFG] Allow SimplifyCFG hoisting to skip over non-matching instructions

SimplifyCFG does some common code hoisting, which is limited
to hoisting a sequence of identical instruction in identical
order and stops at the first non-identical instruction.

This patch allows hoisting instruction pairs over
same-length sequences of non-matching instructions. The
linear asymptotic complexity of the algorithm stays the
same, there's an extra parameter
`simplifycfg-hoist-common-skip-limit` serving to limit
compilation time and/or the size of the hoisted live ranges.

The patch improves SPECv6/525.x264_r by about 10%.

Reviewed By: nikic, dmgreen

Differential Revision: https://reviews.llvm.org/D129370