Bug 60703

Summary:

CSS: Fast path for 'px' lengths should be case-insensitive.

Product:

WebKit

Reporter:

Andreas Kling <kling>

Component:

CSS

Assignee:

Andreas Kling <kling>

Status:

RESOLVED FIXED

Severity:

Normal

CC:

ian

Priority:

Keywords:

Performance

Version:

528+ (Nightly build)

Hardware:

Unspecified

OS:

Unspecified

Attachments:

Description	Flags
Proposed patch	darin: review+

Description Andreas Kling 2011-05-12 09:14:14 PDT

The fast-path for 'px' lengths added on bug 57964 only handles 'px' when in lowercase.
1px, 1PX, 1Px, etc are all valid CSS lengths, and we can easily support them in the fast-path.

Comment 1 Andreas Kling 2011-05-12 09:18:33 PDT

Created attachment 93293 [details]
Proposed patch

Comment 2 Darin Adler 2011-05-12 09:59:26 PDT

Comment on attachment 93293 [details]
Proposed patch

View in context: https://bugs.webkit.org/attachment.cgi?id=93293&action=review

> Source/WebCore/css/CSSParser.cpp:380
> +        && (characters[length - 2] == 'p' || characters[length - 2] == 'P')
> +        && (characters[length - 1] == 'x' || characters[length - 1] == 'X')) {

Another version would be:

    if (length > 2 && (characters[length - 2] | 0x20) == 'p' && (characters[length - 1] | 0x20) == 'x') {

This is more efficient on platforms where branches are expensive. We use this idiom elsewhere in CSSParser.cpp for rgb and we even have a function for it in KURL.cpp (isLetterMatchIgnoringCase) and LinkHash.cpp (matchLetter).

Comment 3 Andreas Kling 2011-05-16 05:42:54 PDT

Committed r86561: <http://trac.webkit.org/changeset/86561>