[all-commits] [llvm/llvm-project] 351d23: [OpenMPOpt] Most SCC's are uninteresting, don't wa...

[Roman Lebedev via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 351d234d866ea441d8f8ad1e9b483a98fd51da19
      https://github.com/llvm/llvm-project/commit/351d234d866ea441d8f8ad1e9b483a98fd51da19
  Author: Roman Lebedev <lebedev.ri at gmail.com>
  Date:   2020-07-27 (Mon, 27 Jul 2020)

  Changed paths:
    M llvm/include/llvm/Transforms/IPO/OpenMPOpt.h
    M llvm/lib/Transforms/IPO/OpenMPOpt.cpp

  Log Message:
  -----------
  [OpenMPOpt] Most SCC's are uninteresting, don't waste time on them (up to 16x faster)

Summary:
This seems obvious in hindsight, but the result is surprising.
I've measured compile-time of `-openmpopt` pass standalone
on RawSpeed unity build, and while there is some OpenMP stuff,
most is not OpenMP. But nonetheless the pass does a lot of costly
preparations before ever trying to look for OpenMP stuff in SCC.

Numbers (n=25): 0.094624s  ->  0.005976s, an -93.68% improvement, or ~16x

Reviewers: jdoerfert

Reviewed By: jdoerfert

Subscribers: yaxunl, hiraditya, guansong, llvm-commits, sstefan1

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D84689