Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 50f118c27cfa82d3409c1ea3addf2aa07d2904d7
https://github.com/WebKit/WebKit/commit/50f118c27cfa82d3409c1ea3addf2aa07d2904d7
Author: Yusuke Suzuki <ysuz...@apple.com>
Date: 2024-03-13 (Wed, 13 Mar 2024)
Changed paths:
M Source/WTF/wtf/HashTraits.h
M Source/WebCore/platform/graphics/WidthCache.h
Log Message:
-----------
[WebCore] Optimize WidthCache further
https://bugs.webkit.org/show_bug.cgi?id=270901
rdar://124512596
Reviewed by Ryosuke Niwa.
This patch further optimizes WidthCache.
1. Ensure that SmallStringKey constructor is always inlined.
2. Add copySmallCharacters. We know that this string is <= 16, very small. Just
doing for-loop is faster for this level of size.
3. Add FloatWithZeroEmptyKeyHashTraits. float / double uses infinity for empty
value. But this means that we cannot use zeroed empty value
for HashMap<T, float> even though T's empty value is zero. We add
FloatWithZeroEmptyKeyHashTraits which uses 0 for empty value, so that
we can ensure that KeyValuePair<T, float>'s empty value is zero. Also, using
character + 1 for key in SingleCharMap so that it can make
empty value zero too.
* Source/WTF/wtf/HashTraits.h:
(WTF::FloatWithZeroEmptyKeyHashTraits::emptyValue):
(WTF::FloatWithZeroEmptyKeyHashTraits::constructDeletedValue):
(WTF::FloatWithZeroEmptyKeyHashTraits::isDeletedValue):
* Source/WebCore/platform/graphics/WidthCache.h:
(WebCore::WidthCache::SmallStringKey::SmallStringKey):
(WebCore::WidthCache::SmallStringKey::copySmallCharacters):
(WebCore::WidthCache::addSlowCase):
Canonical link: https://commits.webkit.org/276034@main
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