[webkit-dev] jit for arm

Gavin Barraclough barraclough at apple.com
Wed Nov 18 00:40:29 PST 2009

 From http://lists.webkit.org/:
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Hmmm, yes, there would seem to be some scope to make that a little  
more descriptive!  ;-)


On Nov 17, 2009, at 11:46 PM, Zoltan Herczeg wrote:

> Hi,
> seems the original mail was sent to both webkit-dev and webkit-help.  
> My
> reply was on webkit-help, and the discussion continued there.
> https://lists.webkit.org/pipermail/webkit-help/2009-November/000380.html
> Perhaps we should clarify better the purpose of these mailing lists,  
> since
> if people can't decide which list is better for them, they do double
> posts.
> Zoltan
>> On Nov 4, 2009, at 8:37 AM, ll Jefferry wrote:
>>> Hi,
>>> when i reading the jit for arm source code, i am not very clear the
>>> functionality of the flowing functions:
>>>        ctiTrampoline
>> This code is used when entering from the C runtime into JIT generated
>> code.  JIT generated code does not necessarily respect C calling
>> conventions, so this routine sets up the stack frame, preserves
>> registers, etc, as necessary to allow the JIT code to be run.
>>>        ctiVMThrowTrampoline
>> To perform certain operations the JIT will call back into C code.
>> Usually the C callback can just return in a perfectly normal fashion
>> and continue execution once it has completed, however in the case  
>> that
>> an exception is thrown special handling is required to change the
>> control flow.  The return address of the C callback is instead  
>> changed
>> to point to this, and this piece of code handles looking up the
>> exception handler at which execution will be resumed.
>>>        ctiOpThrowNotCaught
>> This is used to from within cti_op_throw, which implements the  
>> 'throw'
>> keyword in JavaScript.  The cti_op_throw method will attempt to look
>> up a handler routine that catches the exception.  However if the
>> exception is not caught it is necessary to force an early termination
>> of JIT execution.  The cti_op_throw C callback always modifies its
>> return address, either to point to the code for the appropriate
>> exception handler to catch the exception, or to ctiOpThrowNotCaught  
>> if
>> no handler is found.
>>> could you explain to me?
>>> and another question is that:  in cacheFlush function, why the
>>> system call number is 0xf0002? if it is defined by the toolchain?
>> Zoltan, Gabor?
>>> thanks!
>>> BR,
>>> Jeff
>>> _______________________________________________
>>> webkit-dev mailing list
>>> webkit-dev at lists.webkit.org
>>> http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
>> _______________________________________________
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