On Fr, 2015-04-10 at 16:09 +0200, Stephan Mueller wrote: > Am Freitag, 10. April 2015, 16:00:03 schrieb Hannes Frederic Sowa: > > Hi Hannes, > > >On Fr, 2015-04-10 at 15:25 +0200, Stephan Mueller wrote: > >> I would like to bring up that topic again as I did some more analyses: > >> > >> For testing I used the following code: > >> > >> static inline void memset_secure(void *s, int c, size_t n) > >> { > >> > >> memset(s, c, n); > >> > >> BARRIER > >> > >> } > >> > >> where BARRIER is defined as: > >> > >> (1) __asm__ __volatile__("" : "=r" (s) : "0" (s)); > >> > >> (2) __asm__ __volatile__("": : :"memory"); > >> > >> (3) __asm__ __volatile__("" : "=r" (s) : "0" (s) : "memory"); > > > >Hm, I wonder a little bit... > > > >Could you quickly test if you replace (s) with (n) just for the fun of > >it? I don't know if we should ask clang people about that, at least it > >is their goal to be as highly compatible with gcc inline asm. > > Using > > __asm__ __volatile__("" : "=r" (n) : "0" (n) : "memory"); > > clang O2/3: no mov > > gcc O2/3: mov present > > ==> not good I suspected a problem in how volatile with non-present output args could be different, but this seems not to be the case. I would contact llvm/clang mailing list and ask. Maybe there is a problem? It seems kind of strange to me... Thanks, Hannes -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html