* asm memory barrier question
@ 2004-03-16 14:05 jhjk jhj
2004-03-16 19:57 ` Falk Hueffner
0 siblings, 1 reply; 2+ messages in thread
From: jhjk jhj @ 2004-03-16 14:05 UTC (permalink / raw)
To: gcc
I understand that gcc-help might be a more suitable list to send this but I
think this is a little advanced question and I would like to have an answer
from a developer.
I want to do something like this:
(code)
asm_function_that_alters_general_purpose_registers_WITHOUT_restoring_them();
(other code)
I am quite sure that this will break things. (Right?)
But what about this?
(code)
asm_function-that_alters_general_purpose_registers_without_restoring_them();
asm volatile("" : : : "memory");
(other code)
The program will break?
I am not interested in portability, just gcc.
Thank you in advace for any answer and please CC me.
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: asm memory barrier question
2004-03-16 14:05 asm memory barrier question jhjk jhj
@ 2004-03-16 19:57 ` Falk Hueffner
0 siblings, 0 replies; 2+ messages in thread
From: Falk Hueffner @ 2004-03-16 19:57 UTC (permalink / raw)
To: jhjk jhj; +Cc: gcc
"jhjk jhj" <mmore_benq@hotmail.com> writes:
> (code)
> asm_function-that_alters_general_purpose_registers_without_restoring_them();
> asm volatile("" : : : "memory");
> (other code)
>
> The program will break?
Yes. If you want to alter general purpose registers without restoring
them, add them to the asm's clobber list.
--
Falk
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2004-03-16 19:57 ` Falk Hueffner
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