[webkit-changes] [WebKit/WebKit] e71ed7: [JSC] Reduce unnecessary backtracking code in YarrJIT

[Yusuke Suzuki]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: e71ed7766520ecd35b761622f07967a5593d83bb
      https://github.com/WebKit/WebKit/commit/e71ed7766520ecd35b761622f07967a5593d83bb
  Author: Yusuke Suzuki <ysuzuki at apple.com>
  Date:   2024-08-26 (Mon, 26 Aug 2024)

  Changed paths:
    M Source/JavaScriptCore/yarr/YarrJIT.cpp

  Log Message:
  -----------
  [JSC] Reduce unnecessary backtracking code in YarrJIT
https://bugs.webkit.org/show_bug.cgi?id=278617
rdar://134636872

Reviewed by Yijia Huang.

When the next op is also one character PatternCharacterClass, backtracking should not load index register
since the next op will override it anyway.

Before:
      57:Term PatternCharacterClass checked-offset:(10) [Unicode:(0x1f0a2,0x1f0b2,0x1f0c2,0x1f0d2)]
                <4472> 0x10f3a2078:    ldur     x1, [sp, #64]
      56:Term PatternCharacterClass checked-offset:(10) [Unicode:(0x1f0a3,0x1f0b3,0x1f0c3,0x1f0d3)]
                <4476> 0x10f3a207c:    ldur     x1, [sp, #48]
      55:Term PatternCharacterClass checked-offset:(10) [Unicode:(0x1f0a4,0x1f0b4,0x1f0c4,0x1f0d4)]
                <4480> 0x10f3a2080:    ldur     x1, [sp, #32]
      54:Term PatternCharacterClass checked-offset:(10) [Unicode:(0x1f0a5,0x1f0b5,0x1f0c5,0x1f0d5)]
                <4484> 0x10f3a2084:    ldur     x1, [sp, #16]
      53:Term PatternCharacterClass checked-offset:(10) [Unicode:(0x1f0a6,0x1f0b6,0x1f0c6,0x1f0d6)]
                <4488> 0x10f3a2088:    ldur     x1, [sp]
      52:BodyAlternativeNext minimum-size:(10),checked-offset:(10)
                <4492> 0x10f3a208c:    b        0x10f3a1e78 -> <3960>

After:
      57:Term PatternCharacterClass checked-offset:(10) [Unicode:(0x1f0a2,0x1f0b2,0x1f0c2,0x1f0d2)]
      56:Term PatternCharacterClass checked-offset:(10) [Unicode:(0x1f0a3,0x1f0b3,0x1f0c3,0x1f0d3)]
      55:Term PatternCharacterClass checked-offset:(10) [Unicode:(0x1f0a4,0x1f0b4,0x1f0c4,0x1f0d4)]
      54:Term PatternCharacterClass checked-offset:(10) [Unicode:(0x1f0a5,0x1f0b5,0x1f0c5,0x1f0d5)]
      53:Term PatternCharacterClass checked-offset:(10) [Unicode:(0x1f0a6,0x1f0b6,0x1f0c6,0x1f0d6)]
                <3656> 0x11e840e48:    ldur     x1, [sp]
      52:BodyAlternativeNext minimum-size:(10),checked-offset:(10)
                <3660> 0x11e840e4c:    b        0x11e840ca8 -> <3240>

* Source/JavaScriptCore/yarr/YarrJIT.cpp:

Canonical link: https://commits.webkit.org/282746@main



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