Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: f72ea56abf5c63e3eef3ed11dcd052fe94d133bc
https://github.com/WebKit/WebKit/commit/f72ea56abf5c63e3eef3ed11dcd052fe94d133bc
Author: Yusuke Suzuki <[email protected]>
Date: 2026-05-29 (Fri, 29 May 2026)
Changed paths:
A JSTests/stress/iterator-helpers-fast-path-drain-and-reentrancy.js
A JSTests/stress/map-iterator-fully-packed-table.js
M Source/JavaScriptCore/runtime/ArrayConstructor.cpp
M Source/JavaScriptCore/runtime/IteratorOperations.h
M Source/JavaScriptCore/runtime/JSMapIterator.h
M Source/JavaScriptCore/runtime/JSOrderedHashTableHelper.h
M Source/JavaScriptCore/runtime/JSSetIterator.h
Log Message:
-----------
[JSC] JSOrderedHashTable is overly allocating DataTable
https://bugs.webkit.org/show_bug.cgi?id=315829
rdar://178227340
Reviewed by Yijia Huang.
CloseTable (JSOrderedHashTable) has HashTable and DataTable. HashTable
manages indice, and DataTable is a vector of actual key-values so that
we can maintain insertion order in that vector side. This means that
DataTable size does not need to be the same to HashTable: load-factor is
typically 50% or 75%. So actually held key-values are only up to 75% of
size of HashTable.
This patch computes this and reduces the allocation of DataTable. But we
add one slot IterationSentinel at the end and keeping it empty. So
iterator can stop by detecting empty value. Previously overly allocated
DataTable was guaranteeing this empty sentinel. But now we may use full
of DataTable vector, thus we need this sentinel explicitly.
Also, we found several issues.
1. forEachInIteratorProtocol is introduced in 299358@main. While we are
getting entry index from MapIterator / SetIterator, we are obtaining
storage from iterated Map / Set, not MapIterator / SetIterator's current
cursor.
2. forEachInIteratorProtocol is not draining an iterator, which is
incorrect as for-of should drain it.
3. (1) and (2) exist in tryCreateArrayFromMapIterator as well.
Test: JSTests/stress/map-iterator-fully-packed-table.js
* JSTests/stress/iterator-helpers-fast-path-drain-and-reentrancy.js: Added.
(shouldEq):
(throw.new.Error):
(i.shouldEq.it.next):
* JSTests/stress/map-iterator-fully-packed-table.js: Added.
(assert):
(buildMap):
(buildSet):
(drainMap):
(drainSet):
* Source/JavaScriptCore/runtime/ArrayConstructor.cpp:
(JSC::tryCreateArrayFromMapIterator):
* Source/JavaScriptCore/runtime/IteratorOperations.h:
(JSC::forEachInIteratorProtocol):
* Source/JavaScriptCore/runtime/JSMapIterator.h:
* Source/JavaScriptCore/runtime/JSOrderedHashTableHelper.h:
(JSC::JSOrderedHashTableHelper::dataCapacity):
(JSC::JSOrderedHashTableHelper::dataTableSize):
(JSC::JSOrderedHashTableHelper::tableSize):
(JSC::JSOrderedHashTableHelper::tableSizeSlow):
(JSC::JSOrderedHashTableHelper::expandIfNeeded):
(JSC::JSOrderedHashTableHelper::transitAndNext):
* Source/JavaScriptCore/runtime/JSSetIterator.h:
Canonical link: https://commits.webkit.org/314169@main
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