Re: [Qemu-devel] [PATCH 1/3] Add support for target helper functions which don't return

[Stefan Weil <sw@weilnetz.de>]

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Am 19.03.2012 11:45, schrieb Andreas Färber:
> Am 18.03.2012 23:16, schrieb Stefan Weil:
>> Most functions which handle exceptions don't return.
>>
>> With a compiler attribute (added by QEMU_NORETURN),
>> gcc can optimize the code.
>
> Do you have any numbers?

Yes, of course: for (;;) { printf("%ld\n", random()); } :-)

To be honest, I don't expect large savings of code (some bytes for the 
function return
which is no longer needed), nor will there be a huge gain in execution 
speed.

It's more for documentation purposes that this attribute is useful here.
|We might also add a compiler warning for missing attributes some day
(-Wsuggest-attribute=||noreturn|) - it is surprising how many functions 
never return!

Regards,
Stefan

>
>>
>> Signed-off-by: Stefan Weil <sw@weilnetz.de>
>
> Seems like a sensible optimization,
>
> Reviewed-by: Andreas Färber <afaerber@suse.de>
>
> Andreas

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