Hi Rémi, On Tue, Feb 13, 2018 at 11:31 AM, Rémi Denis-Courmont <[email protected]> wrote: > Le tiistaina 13. helmikuuta 2018, 18.16.55 EET Sean McGovern a écrit : >> I discovered this while doing a full valgrind FATE run on a POWER7 >> machine -- among others, fate-noproxy failed. >> >> The result for the noproxy test in this case makes me believe it is >> using the aforementioned behaviour of memcmp(): >> >> ==47650== Memcheck, a memory error detector >> ==47650== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al. >> ==47650== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info >> ==47650== Command: /home/seanmcg/build/libav-gcc7/libavformat/tests/noproxy >> ==47650== >> ==47650== Invalid read of size 8 >> ==47650== at 0x1000646C: match_host_pattern (network.c:255) >> ==47650== by 0x1000646C: ff_http_match_no_proxy (network.c:284) >> ==47650== by 0x100059CF: test (noproxy.c:25) >> ==47650== by 0x100057BB: main (noproxy.c:34) >> ==47650== Address 0x4480054 is 20 bytes inside a block of size 23 alloc'd >> ==47650== at 0x40861E4: malloc (vg_replace_malloc.c:298) >> ==47650== by 0x4088AD3: realloc (vg_replace_malloc.c:785) >> ==47650== by 0x100A9A2F: av_realloc (mem.c:116) >> ==47650== by 0x100A9A2F: av_strdup (mem.c:215) >> ==47650== by 0x10006267: ff_http_match_no_proxy (network.c:272) >> ==47650== by 0x100059CF: test (noproxy.c:25) >> ==47650== by 0x100057BB: main (noproxy.c:34) >> ==47650== >> >> <..snipped for brevity, pattern repeats for each test..> >> >> I found the following bug reports which seemed relevant in the GCC Bugzilla: >> >> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52171 and >> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78257 >> >> I don't think this is a compiler bug or cargo-culting, although Clang >> does not appear to exhibit this behaviour. > > This is not so much a GCC bug as an incompatibility between GCC and valgrind, > likely because not many people care about POWER: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80479 > https://bugs.kde.org/show_bug.cgi?id=386945 > > I don't think this patch is valid anyway, and even if it were, I don't think > it is a sane thing to do. Why replace just that one call site? And what about > all other <string.h> that GCC has built-ins for? By this line of thinking, you > should reinvent much of <string.h> - just because valgrind breaks on POWER. >
OK. Fair enough. I will drop this patch. Sorry for wasting people's time. -- Sean McG. _______________________________________________ libav-devel mailing list [email protected] https://lists.libav.org/mailman/listinfo/libav-devel
