lkml.org 
[lkml]   [2007]   [Jul]   [23]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
FromAndi Kleen <>
SubjectRe: [PATCH 3/8] i386: bitops: Rectify bogus "+m" constraints
DateMon, 23 Jul 2007 18:37:27 +0200
On Monday 23 July 2007 18:05:43 Satyam Sharma wrote:
> From: Satyam Sharma <ssatyam@cse.iitk.ac.in>
> 
> [3/8] i386: bitops: Rectify bogus "+m" constraints
> 
> From the gcc manual:
> 
>   Extended asm supports input-output or read-write operands. Use the
>   constraint character `+' to indicate such an operand and list it with
>   the output operands. You should only use read-write operands when the
>   constraints for the operand (or the operand in which only some of the
>   bits are to be changed) allow a register.
> 
> So, using the "+" constraint modifier for memory, like "+m" is bogus.
> We must simply specify "=m" which handles the case correctly.

I checked with Honza (cc'ed) and he stated that the + are really needed
at least in newer gcc.

-Andi
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-07-23 16:41    [from the cache]
©2003-2008