[webkit-changes] [WebKit/WebKit] e4d380: [JSC][GreedyRegAlloc] Tune the spill heuristic

[Dan Hecht]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: e4d3808183f589bce4fde083f051b5ead06ec8b7
      https://github.com/WebKit/WebKit/commit/e4d3808183f589bce4fde083f051b5ead06ec8b7
  Author: Dan Hecht <dan.hecht at apple.com>
  Date:   2025-02-27 (Thu, 27 Feb 2025)

  Changed paths:
    M Source/JavaScriptCore/b3/air/AirAllocateRegistersByGreedy.cpp

  Log Message:
  -----------
  [JSC][GreedyRegAlloc] Tune the spill heuristic
https://bugs.webkit.org/show_bug.cgi?id=288724
rdar://145757691

Reviewed by Yijia Huang.

>From jetstream runs, using max to aggregate the cost of
the conflicts when deciding whether to evict appears universally
worse, so leave the aggregator as add.

Using the divide by size with a bias of 1000 greatly improves
the spilling choice on a few subtests while keeping others
relatively stable, on both ARM64 and x64.

* Source/JavaScriptCore/b3/air/AirAllocateRegistersByGreedy.cpp:

Canonical link: https://commits.webkit.org/291238@main



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