No, sorry, no idea. I try to avoid the C++ RTTI system ;)

I was thinking about tweaking the outlining-limit (see: 
http://mozakai.blogspot.de/2013/08/outlining-workaround-for-jits-and-big.html), 
if the generated code contains very large functions, JS engines may not 
optimize them. I was bitten by this problem a long time ago with sqlite. If 
this would be a problem you would get warnings about large functions in the 
linker step.

But dynamic_cast, I have no idea what the problem could be... even if it is 
used heavily I couldn't imagine what would be so expensive about it.

Is the performance in Firefox roughly the same as a native optimized 
executable, or is this also a lot slower?

An isolated test case might be helpful, it could actually be a more serious 
code generation issue and/or a pathological case for Google's JS engine (in 
this case it might be useful to file a ticket in the Chromium issue 
tracker).

Cheers,
-Floh.

Am Dienstag, 11. August 2015 16:05:39 UTC+2 schrieb Laurent Pugin:
>
>
>> I would advice to compile your code with optimization on and -g2 
>> (preserves function names), and then use Chrome's JS profiler (part of 
>> Chrome Developer Tools panel). This should give you an idea what functions 
>> are especially slow and perhaps provide a hint which C/C++ code is the 
>> problem.
>>
>
> It seems that dynamic_cast takes quite some of the time (nearly 50%?). Any 
> thoughts?
>
>

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