[Webkit-unassigned] [Bug 53003] Web Inspector: [JSC] implement setting breakpoints by line:column

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=53003





--- Comment #53 from Peter Wang <peter.wang at torchmobile.com.cn>  2012-07-15 00:45:42 PST ---
In theory, my patch brings extra calculation only in "parsing" phase, since it adds a counter to record the column of "token", and this extra calculation is a very small part of the calculation of "parsing". For the generated bytecode, only instruction "debug" has one extra parameter.

With my local compiled Qt Browser, I did some times of SunSpider test. The results are fluctuating, below data are the ones with narrowest fluctuating range:
with my patch 208.8ms ±0.8%
without my patch 209.6ms ±0.6%

The feature of debugging with uglified JS code is very important now, since most JS code in live sites are uglified. I tried to implement this feature avoiding modification of JSC, but failed. It seems let JSC provide the "column" info is appropriate, since in "parsing" phase JSC "knows" the "column" info of every token, it just needs to be recorded. 

I'd like to discuss the potential impact of my patch, since we must be careful when changing JSC. Welcome comments.

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