[Webkit-unassigned] [Bug 42264] Prepare YARR JIT for matching regexps with iterative parentheses

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=42264


Peter Varga <pvarga at inf.u-szeged.hu> changed:

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--- Comment #7 from Peter Varga <pvarga at inf.u-szeged.hu>  2010-07-28 03:06:37 PST ---
Created an attachment (id=62807)
 --> (https://bugs.webkit.org/attachment.cgi?id=62807)
proposed patch v3

Here is another patch to prepare the YARR JIT logic to be capable for iterative
parentheses matching. This solution is different from the previous ones.

The goal was to free a register in order to use a new heap memory space
for JIT. The logic stores the results of subpattern matching on the
preallocated stack frame instead of an array allocated on heap (output). 
The pointer of the result array (output) is stored on the stack, therefore this 
array can be filled with information from the stack after the whole pattern matching
process completed.

This solution causes more stack usage but it uses preallocated stack.
Here are the performance results:

                    ref                 mod
regexp-dna:    22.1ms +/- 1.0%    22.1ms +/- 1.0%
regexp-v8:    431.6ms +/- 2.2%    430.9ms +/- 2.3%

At the moment I don't see any better way to solve this problem by
modificating the current YARR logic. Of course any other ideas are welcome.

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