| Summary: | Refactored string parsing in the lexer | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Product: | WebKit | Reporter: | Zoltan Herczeg <zherczeg> | ||||||
| Component: | JavaScriptCore | Assignee: | Nobody <webkit-unassigned> | ||||||
| Status: | RESOLVED FIXED | ||||||||
| Severity: | Enhancement | CC: | oliver, webkit.review.bot | ||||||
| Priority: | P2 | ||||||||
| Version: | 528+ (Nightly build) | ||||||||
| Hardware: | All | ||||||||
| OS: | All | ||||||||
| Attachments: |
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Created attachment 60514 [details]
patch
Attachment 60514 [details] did not pass style-queue:
Failed to run "['WebKitTools/Scripts/check-webkit-style', '--no-squash']" exit_code: 1
JavaScriptCore/parser/Lexer.cpp:398: An else if statement should be written as an if statement when the prior "if" concludes with a return, break, continue or goto statement. [readability/control_flow] [4]
Total errors found: 1 in 3 files
If any of these errors are false positives, please file a bug against check-webkit-style.
Created attachment 60515 [details]
Lexer.cpp.gcov
The gcov profile is for concat-jquery-mootools-prototype Hm, maybe I have an idea what is causing the slowdown. The original code, there was two makeIdentifier call. I did a few changes before, and realized I removed one of them (one was for a fast path when the m_buffer was not needed). I put it back (thought it was a stupid move), and the slowdown appeared again. Later I refactored the code, that even though I keep the fast case, only one makeIdentifier appeared in the code, and the speed was nearly as fast as the patch added to this bug. Maybe the ALWAYS_INLINE makeIdentifier is more computation expensive than I expected... at least on my machine. Comment on attachment 60514 [details]
patch
r=me
Landed in http://trac.webkit.org/changeset/62628 Closing bug |
The current sunspider parse-only results are the following: ============================================================================= ** TOTAL **: 1.044x as fast 33.1ms +/- 1.9% 31.7ms +/- 1.1% significant ============================================================================= jquery: - 5.1ms +/- 4.4% 5.1ms +/- 4.4% 1.3.2: - 5.1ms +/- 4.4% 5.1ms +/- 4.4% mootools: 1.080x as fast 5.4ms +/- 6.8% 5.0ms +/- 0.0% significant 1.2.2-core-nc: 1.080x as fast 5.4ms +/- 6.8% 5.0ms +/- 0.0% significant prototype: - 6.1ms +/- 3.7% 6.0ms +/- 0.0% 1.6.0.3: - 6.1ms +/- 3.7% 6.0ms +/- 0.0% concat: 1.058x as fast 16.5ms +/- 2.3% 15.6ms +/- 2.4% significant jquery-mootools-prototype: 1.058x as fast 16.5ms +/- 2.3% 15.6ms +/- 2.4% significant But it was not before, actually it was a 5% slowdown. This patch was actually completed a week ago, and I didn't really changed it. I planned to submit a patch with a gcov output and ask for help. (I usually run sunspider 10-15 times before choose the best measurement, to lessen the effect of deviation caused by the OS. So this patch was really slower before, and faster now, albeit I think it is not the effect of the patch, more likely the changed binary structure) Anyway, the gcov output is also attached.