Re: [PATCH 7/8] i386: bitops: Kill needless usage of __asm__ __volatile__

[Andi Kleen]

On Monday 23 July 2007 18:06:03 Satyam Sharma wrote:
> From: Satyam Sharma <ssatyam@xxxxxxxxxxxxxx>
> 
> [7/8] i386: bitops: Kill needless usage of __asm__ __volatile__
> 
> Another oddity I noticed in this file. The semantics of __volatile__
> when used to qualify inline __asm__ are that the compiler will not
> (1) elid, or, (2) reorder, or, (3) intersperse, our inline asm with
> the rest of the generated code.
> 
> However, we do not want these guarantees in the unlocked variants of the
> bitops functions. 

I thought so too and did a similar transformation while moving
some string functions out of line. After that recent misadventure
I would be very very careful with this.

Overall I'm sorry to say, but the risk:gain ratio of this
patch is imho totally out of whack.

It took a long time to get bitops.h correct and as far as we know
it is compiled correctly currently. You risk all at for very dubious
improvements.

-Andi



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