> -----Original Message----- > From: Qiu, Michael > Sent: Monday, December 08, 2014 4:24 PM > To: Wodkowski, PawelX; dev at dpdk.org > Subject: Re: error: value computed is not used > > On 2014/12/8 19:00, Wodkowski, PawelX wrote: > >> lib/librte_pmd_enic/enic_main.c: In function 'enic_set_rsskey': > >> lib/librte_pmd_enic/enic_main.c:862:2: error: value computed is not used > >> > >> I dig out that, it was ome issue of the macros rte_memcpy() > >> #define rte_memcpy(dst, src, n) \ > >> ((__builtin_constant_p(n)) ? \ > >> memcpy((dst), (src), (n)) : \ > >> rte_memcpy_func((dst), (src), (n))) > >> > >> When I use only (n) instead of (__builtin_constant_p(n), it will pass( I > >> know that it was incorrect, just a experiment). > >> > >> But I try to use inline function instead of macros: > >> static inline void * rte_memcpy(void *dst, const void *src, size_t n) > >> { > >> return __builtin_constant_p(n) ? memcpy(dst, src, n) : > >> rte_memcpy_func(dst, src, n); > >> } > >> > >> It will pass:), and works, this could be one potential workaround fix. > >> > >> Who knows why? The root cause is what? > >> > >> I've no idea about this. > >> > > I got the same issue while ago. I don't remember exactly everything > > but my conclusion was that there was some bug in compiler. I think, > > when 'n' I constant and/or small compiler is inlining memcpy and throwing > > everything else (including returned value). In that case error is not > > produced (I think this is a bug in compiler). In other case it is computing > > some value calling memcpy or rte_ memcpy and you should at least > > explicitly throw it away by casting to void. I like solution with static > > Actually, I try to pass "n" as a Int value like 4, it still report this > error :)
My workaround was: (void) rte_memcpy(...); But this is only a workaround. > > > inline but someone else should spoke about possible side effects. > > Yes, but as I know inline is better than macros. > > Thanks, > Michael > > > > Pawel > > > >