[all-commits] [llvm/llvm-project] 7b0f63: [SimplifyCFG] Allow SimplifyCFG hoisting to skip o...

Momchil Velikov via All-commits all-commits at lists.llvm.org
Sun Jul 31 23:57:00 PDT 2022

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7b0f6378e211e881c574748090a86beeab264ab3
  Author: Momchil Velikov <momchil.velikov at arm.com>
  Date:   2022-08-01 (Mon, 01 Aug 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: dmgreen

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

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