[webkit-changes] [WebKit/WebKit] 8683d7: [JSC] better compilation defaults for arm 32-bit

[Guillaume Emont]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 8683d7558197d47d60fc1df3f823eebd16dd1ab0
      https://github.com/WebKit/WebKit/commit/8683d7558197d47d60fc1df3f823eebd16dd1ab0
  Author: Guillaume Emont <guijemont at igalia.com>
  Date:   2022-10-12 (Wed, 12 Oct 2022)

  Changed paths:
    M Source/JavaScriptCore/runtime/Options.cpp

  Log Message:
  -----------
  [JSC] better compilation defaults for arm 32-bit
https://bugs.webkit.org/show_bug.cgi?id=244253

Reviewed by Justin Michaud.

The defaults for various compilation parameters are not optimal for arm
32-bit, especially considering that compilation happens in the main
thread on that platform, thus making big compilations more costly.

This change introduces new default for arm, found using
scikit-optimize's gp_minimize()[1] and running watch-cli.js from
JetStream2 with jsc compiled in 32-bit.

On an average of 5 runs, these parameters provide a score improvement of
1.60% on a raspberry pi 3, and 1.56% on a raspberry pi 4 with similar
conditions.

[1] https://scikit-optimize.github.io/stable/modules/generated/skopt.gp_minimize.html

* Source/JavaScriptCore/runtime/Options.cpp:
(JSC::overrideDefaults): new defaults of various parameters for CPU(ARM)

Canonical link: https://commits.webkit.org/255425@main