I found some time and got a few bits of embind working:

https://github.com/imvu/emscripten/commit/afc59d1e331c445a5762f6a5751b86740b1ebbeb
https://github.com/imvu/emscripten/commit/228b4fc349f1cdf592821d988240e7d9543462be

When I get a minimal demo up and running in fastcomp/asm.js, I'll submit a
pull request.



On Mon, Mar 17, 2014 at 3:11 PM, Dean Elhard <[email protected]> wrote:

> I would be interested in helping, although I haven't looked at how it
> works, so I am not sure what exactly is involved...
>
>
> On Wednesday, March 5, 2014 2:33:34 AM UTC-7, Chad Austin wrote:
>
>> True!  We do want to use fastcomp but wasn't sure the advantages
>> outweighed the embind porting work.
>>
>> However, because Dean asked, I sat down and took a look tonight, and got
>> a few functions working.  Most of the work is in getting rid of the
>> function pointer casts, but it seems quite straightforward.
>>
>> I'll poke away and send pull requests when I have them...  If anyone
>> wants to help, let me know.  :)
>>
>>
>> On Tue, Mar 4, 2014 at 8:27 PM, Alon Zakai <[email protected]> wrote:
>>
>>> Note that fastcomp supports a growable heap in asm.js mode. It will not
>>> validate as asm.js, but should still get much of the speedups from it, just
>>> without guarantees and probably not all of them.
>>>
>>> - Alon
>>>
>>>
>>>
>>> On Tue, Mar 4, 2014 at 2:46 PM, Chad Austin <[email protected]> wrote:
>>>
>>>> Hi Dean,
>>>>
>>>> We should port embind to asm.js!  It's certainly a bit of work, but
>>>> probably not too hard.  It's really just that nobody's done the work yet.
>>>> Since IMVU, my employer, can't use asm.js until it supports a growable heap
>>>> (and perhaps closure compiler), we aren't terribly motivated to do the 
>>>> work.
>>>>
>>>> That said, part of me just wants to bite the bullet and do the
>>>> conversion myself if I can find the time.  :)
>>>>
>>>> In case someone else wants to take a crack at it, here is what I know:
>>>>
>>>> There are a couple places where embind uses reinterpret_cast on
>>>> function pointers in order to pass more arguments than their prototypes
>>>> specify.  For example, see https://github.com/kripken/
>>>> emscripten/blob/master/system/include/emscripten/val.h#L67
>>>>
>>>> Those functions need to be converted to varargs.  (At the time, I think
>>>> we were blocked on a varargs issue with the old LLVM, but that may not be
>>>> an issue anymore.)
>>>>
>>>> The other issue is that embind relies on JavaScript being able to look
>>>> up functions by indexing into FUNCTION_TABLE[x].  asm.js doesn't have a
>>>> single function table: it has a whole bunch of function tables, one for
>>>> each possible type signature.
>>>>
>>>> Thus, on the C++ side, we need a way to take a C++ signature (like
>>>> float(const void*, int&)) and turn that into a string ("fii") that we can
>>>> use to select one of the function tables on the embind side.  Embind would
>>>> also need the compiler to output a table from signature to the appropriate
>>>> function table.  The compiler-generated glue would look something like:
>>>>
>>>> var FUNCTION_TABLES = {
>>>>   vi: FUNCTION_TABLE_vv,
>>>>   fii: FUNCTION_TABLE_fii,
>>>>   ...
>>>> };
>>>>
>>>> I *think* that if we had those two things, we could make embind work
>>>> with asm.js.
>>>>
>>>> *waves hands a bit* :)
>>>>
>>>> Hope that's helpful,
>>>> Chad
>>>>
>>>> On Tue, Mar 4, 2014 at 2:28 PM, Dean Elhard <[email protected]> wrote:
>>>>
>>>>> Since 1.13.0 is moving to the fastcomp compiler, which only supports
>>>>> asm.js, and embind doesn't work with asm.js, it seems that anyone relying
>>>>> on embind is being left behind.
>>>>>
>>>>> The issues I see on github regarding embind and asm.js are old and
>>>>> inactive, and indicate no plans to make embind work with asm.js any time
>>>>> soon.
>>>>>
>>>>> Any comment on the future of embind (if any), or what will replace it?
>>>>>
>>>>>
>>>>>  --
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>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Chad Austin
>>>> Technical Director, IMVU
>>>> http://engineering.imvu.com <http://www.imvu.com/members/Chad/>
>>>> http://chadaustin.me
>>>>
>>>>
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>>>
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>>
>>
>>
>> --
>> Chad Austin
>> Technical Director, IMVU
>> http://engineering.imvu.com <http://www.imvu.com/members/Chad/>
>> http://chadaustin.me
>>
>>
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-- 
Chad Austin
Technical Director, IMVU
http://engineering.imvu.com <http://www.imvu.com/members/Chad/>
http://chadaustin.me

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