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On Mar 9, 2009, at 8:36 AM, "rguenth at gcc dot gnu dot org" <gcc-bugzi...@gcc.gnu.org > wrote:



------- Comment #1 from rguenth at gcc dot gnu dot org 2009-03-09 15:36 ------- You need to specify that the registers are clobbered by the asm. The only way to do that is to use output constraints ("+D", "+c", etc.) on proper
temporaries.

 int lent = len;
 char *dstt = dst;
 char *srct = src;
 __asm__ __volatile__(
                      "cld\n\t"
                      "rep movsb"
                      : "+c" (lent), "+D"(dstt), "+S"(src)
                     );
Otherwise GCC thinks the registers still hold the original value.

Oh and mark this inline-ask as clobbering memory.




--

rguenth at gcc dot gnu dot org changed:

          What    |Removed                     |Added
--- --- ----------------------------------------------------------------------
            Status|UNCONFIRMED                 |RESOLVED
        Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39403

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