[webkit-changes] [WebKit/WebKit] 6ec908: [JSC] Support ZeroReg for the result in Select

[Yusuke Suzuki]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 6ec908a21a6f4e805f4e888712e369b088bb582b
      
https://github.com/WebKit/WebKit/commit/6ec908a21a6f4e805f4e888712e369b088bb582b
  Author: Yusuke Suzuki <ysuz...@apple.com>
  Date:   2026-04-06 (Mon, 06 Apr 2026)

  Changed paths:
    M Source/JavaScriptCore/b3/B3LowerToAir.cpp
    M Source/JavaScriptCore/b3/air/AirOpcode.opcodes
    M Source/JavaScriptCore/b3/testb3.h
    M Source/JavaScriptCore/b3/testb3_1.cpp
    M Source/JavaScriptCore/b3/testb3_6.cpp

  Log Message:
  -----------
  [JSC] Support ZeroReg for the result in Select
https://bugs.webkit.org/show_bug.cgi?id=311548
rdar://174136942

Reviewed by Yijia Huang.

This patch adds support for Select with ZeroReg for result position.
So, we can emit

    csel      x6, x4, xzr, cs

instead of consuming another register for xzr position.

Tests: Source/JavaScriptCore/b3/testb3_1.cpp
       Source/JavaScriptCore/b3/testb3_6.cpp

* Source/JavaScriptCore/b3/B3LowerToAir.cpp:
* Source/JavaScriptCore/b3/air/AirOpcode.opcodes:
* Source/JavaScriptCore/b3/testb3.h:
* Source/JavaScriptCore/b3/testb3_1.cpp:
(run):
* Source/JavaScriptCore/b3/testb3_6.cpp:
(testSelectInt32WithZeroElse):
(testSelectInt64WithZeroElse):
(testSelectInt32ImmWithZeroElse):
(testSelectTestWithZeroElse):

Canonical link: https://commits.webkit.org/310656@main



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