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Re: Single asm instruction
On Mon, Feb 03, 2003 at 04:46:28PM +0200, Gilad Benjamini wrote:
> AFAIK, embedded assembly code (__asm) can not be optimized by the
> compiler.
It can't be optimised away, but register and memory usage can be
optimised.
> I heard through the grapevine that you can embed a single assembly
> instruction,
> using a "__" prefix, and in this case the compiler CAN optimize. The
> code.
> Is this correct ?
No.
> What's the exact syntax ?
__asm__ ( "asm code" : "input variables" : "output variables" : "clobber" );
> Where is this documented ?
The gcc info pages (try tkinfo or pinfo, they're better info readers
than info). Also be sure to check the links section on
kernelnewbies.org, we have a couple of links to inline assembly.
BIG FAT WARNING: Try to avoid assembly! It makes your code non-portable
and hard to maintain!
Erik
--
J.A.K. (Erik) Mouw
Email: J.A.K.Mouw@its.tudelft.nl mouw@nl.linux.org
WWW: http://www-ict.its.tudelft.nl/~erik/
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