[xdebug-general] Re: slow codecoverage

On Thu, 10 May 2007, Are Pedersen wrote:

> I took a peek into the xdebug source, and when the XDEBUG_CC_UNUSED
> setting is on, it apparently scans the whole op-code tree from within
> zend (I'm not very familiar with php internals...). When it doesn't do
> this it goes pretty fast...though some slowdown is there, but not near
> that much.
>
> So the question is really if there is room to optimize... Since I'm no C
> guru it's somewhat hard to determine for myself.

Unfortunately it has to scan the whole opcode arrays as otherwise it's
impossible to detect which lines can be executed or not. The algorithm
has to follow every branch in the oparrays to do so. It's possible that
I can get a *little* bit more performance out it by slightly optimizing
the algorithm, but the magnitude of the slowdown you're seeing is not
going away. But be happy that it's only 50% slower, the gcov thing that
Sebastian mentioned makes everything 30-40 times slower :)

regards,
Derick

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