[all-commits] [llvm/llvm-project] 0baf13: [lld/mac] Parallelize code signature computation

[Nico Weber via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0baf13e282abe226069d9e18ca60dc63dfcbdb28
      https://github.com/llvm/llvm-project/commit/0baf13e282abe226069d9e18ca60dc63dfcbdb28
  Author: Nico Weber <thakis at chromium.org>
  Date:   2022-06-21 (Tue, 21 Jun 2022)

  Changed paths:
    M lld/MachO/SyntheticSections.cpp

  Log Message:
  -----------
  [lld/mac] Parallelize code signature computation

According to ministat, this is a small but measurable speedup
(using the repro in PR56121):

    N           Min           Max        Median           Avg        Stddev
x  10     3.7439518     3.7783802     3.7730219     3.7655502   0.012375226
+  10     3.6149218      3.692198     3.6519327     3.6502951   0.025905601
Difference at 95.0% confidence
	-0.115255 +/- 0.0190746
	-3.06078% +/- 0.506554%
	(Student's t, pooled s = 0.0203008)

(Without 858e8b17f7365, this change here to use parallelFor is an 18% speedup,
and doing 858e8b17f7365 on top of this change is just a 2.55% +/- 0.58% win.
Doing both results in a total speedup of 20.85% +/- 0.44%.)

Differential Revision: https://reviews.llvm.org/D128298