Optimizing nqp-js-on-js to make it fast enough to compile Rakudo

By Paweł Murias on April 14, 2016 1:27 PM

Having failed to find a working profiler on npm I ended up webpacking nqp-js-on-js and profiling it directly in Chrome.
It turns out the first big slowdown was the lack of multi caching.
I implemented them.
The second big slowdown was actually the slurp() function.
MoarVM doesn't handle concatenation large amounts of huge strings very well so the cross compiler so instead of concatenating bits of javascript code it's often much faster to write them to disk and then slurp it back in.
On the nqp-js-on-js due to a misset buffer size slurp turned out sluggish.
Due to profiling a webpacked version (which doesn't do IO as it runs in Chrome) this has baffled me for a bit.
Changing the nqp::readallfh buffer size from 10 to 32768 speed up stuff a lot and I'm back to compiling rakudo.
Based on the output of the profiling there seem to be a few low hanging fruit optimalizations for bunch of easy ~5% speedups but I'll work on them later on as having actual Perl 6 running instead of NQP will give me a better vision of how we want to optimize things.