Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 8cb7e38ecdc81eae11a62e192220f9f5658cd4d9
https://github.com/WebKit/WebKit/commit/8cb7e38ecdc81eae11a62e192220f9f5658cd4d9
Author: Vassili Bykov <[email protected]>
Date: 2026-06-04 (Thu, 04 Jun 2026)
Changed paths:
M Source/JavaScriptCore/assembler/CPU.h
M Source/JavaScriptCore/bytecode/InlineCacheHandler.cpp
M Source/JavaScriptCore/bytecode/InlineCacheHandler.h
M Source/JavaScriptCore/parser/Lexer.h
Log Message:
-----------
[JSC] Optimize the layout of InlineCacheHandler
https://bugs.webkit.org/show_bug.cgi?id=316163
rdar://178579821
Reviewed by Yusuke Suzuki and Dan Hecht.
[This is a re-landing of https://github.com/WebKit/WebKit/pull/66329
with a fix to disable the layout check in Asan release builds.]
This patch optimizes the layout of InlineCacheHandler to place hot fields
within the same
cache line and reduce padding.
Key changes:
- m_next is grouped with other hot fields and the class is made
CACHE_LINE_ALIGNED to
ensure hot fields land on one cache line.
- m_structureID is placed as the first field. The instance begins with a hidden
4-byte
refcount, and placing m_structureID first uses the 4 bytes between the refcount
and the
first pointer-size field instead of wasting them on padding. Also, m_cacheType
and
m_makesJSCalls are placed after the 4-byte m_offset, to use 2 out of 4 bytes of
padding
between m_offset and m_uid.
- CACHE_LINE_ALIGNED is moved from Lexer.h to a reusable header CPU.h.
Testing: covered by existing tests.
Canonical link: https://commits.webkit.org/314595@main
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