llvm dev - Sep 2009 - [LLVMdev] [Fwd: Re: An alternate implementation of exceptions]

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From: "Mikael Lyngvig" <mikael at lyngvig.org>
Subject: Re: [LLVMdev] An alternate implementation of exceptions
Date: Sun, 6 Sep 2009 09:53:29 +0200 (CEST)
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On 2009-09-06 12:37, Cédric Venet wrote:
>
>
> ------------------------------------------------------------------------
>
> Subject:
> Re: [LLVMdev] An alternate implementation of exceptions
> From:
> "Mikael Lyngvig" <mikael at lyngvig.org>
> Date:
> Sun, 6 Sep 2009 09:53:29 +0200 (CEST)
> To:
> Cédric Venet <cedric.venet at laposte.net>
>
> To:
> Cédric Venet <cedric.venet at laposte.net>
>
>
> Hi Cédric,
>
> Do you mind forwarding this email to the list?  I can't seem to find
the
> list address anywhere.
>
> Thanks in advance (even if you don't forward it :-).
>
> Cheers,
> Mikael
>
>
>   
>> The last few mail didn't go to the mailing list it seems, it is not
the
>> reply to by default...
>>
>> Mikael Lyngvig a écrit :
>>     
>>> Hi,
>>>
>>> I've been playing around myself for the past few hours.  I got
something
>>> like this:
>>>
>>>    1. OpenWatcom C++ v1.8: three times speedup.
>>>    2. Microsoft Visual C++ v9.0: 10 PERCENT speedup.
>>>
>>> I am having trouble linking with GCC - it complains about
unresolved
>>> symbols (__cxa_allocate_exception, etc.).
>>>
>>> But it seems that my initial findings, of four to five times
speedup,
>>> were
>>> only caused by the fact that I only tried out the OpenWatcom
compiler.
>>> Apparently this compiler's exception handling is very slow,
which could
>>> probably be guessed from the fact that it explicitly calls setjmp()
in
>>> try
>>> blocks and longjmp() in throw statements.
>>>
>>> But, still, this is testing the standard C method of explicitly
checking
>>> the return code.  As no compiler generates the stc/ret and jc
>>> instruction
>>>       
Could LLVM codegen use the carry flag for a return of i1?
Actually for a multiple return instruction where one of the returned
values is an i1?

Best regards,
--Edwin