[webkit-changes] [WebKit/WebKit] 855b9c: Use StringView in CSSParserToken and simplify its ...

[Chris Dumez]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 855b9cf6ef5a2b8b5ead0d06314779d7fd1884fc
      https://github.com/WebKit/WebKit/commit/855b9cf6ef5a2b8b5ead0d06314779d7fd1884fc
  Author: Chris Dumez <cdumez at apple.com>
  Date:   2023-10-02 (Mon, 02 Oct 2023)

  Changed paths:
    M Source/WTF/wtf/text/StringView.cpp
    M Source/WTF/wtf/text/StringView.h
    M Source/WebCore/css/CSSVariableData.cpp
    M Source/WebCore/css/parser/CSSParserToken.cpp
    M Source/WebCore/css/parser/CSSParserToken.h

  Log Message:
  -----------
  Use StringView in CSSParserToken and simplify its code
https://bugs.webkit.org/show_bug.cgi?id=262498

Reviewed by Darin Adler.

Use StringView in CSSParserToken and simplify its code.

Previously, CSSParserToken wasn't using StringView internally for better bit packing,
as the size of this object matters a lot. Instead, do better bit packing in StringView
so that CSSParserToken can use it without increasing its size (24 bits on my
macBookPro M1).

To better bit-pack StringView, we rely on PackedPtr to fit the is8Bit flag in the same
word as the character pointer.

This is performance neutral on Speedometer.

* Source/WTF/wtf/text/StringView.cpp:
(WTF::StringView::convertToASCIILowercase const):
(WTF::StringView::convertToASCIIUppercase const):
* Source/WTF/wtf/text/StringView.h:
(WTF::StringView::StringView):
(WTF::StringView::characters8 const):
(WTF::StringView::characters16 const):
* Source/WebCore/css/CSSVariableData.cpp:
(WebCore::CSSVariableData::updateBackingStringsInTokens):
* Source/WebCore/css/parser/CSSParserToken.cpp:
(WebCore::CSSParserToken::CSSParserToken):
(WebCore::CSSParserToken::convertToDimensionWithUnit):
(WebCore::CSSParserToken::copyWithUpdatedString const):
* Source/WebCore/css/parser/CSSParserToken.h:
(WebCore::CSSParserToken::value const):
(WebCore::CSSParserToken::updateString):
(WebCore::CSSParserToken::initValueFromStringView): Deleted.
(WebCore::CSSParserToken::updateCharacters): Deleted.

Canonical link: https://commits.webkit.org/268760@main