From: René Scharfe <l.s.r@web.de>
Date: Mon, 01 May 2017 11:23:28 GMT
Subject: Re: [PATCH] cache-tree: reject entries with null sha1
Message-ID: <12c3312c-30a1-2cb1-8f05-63bb663bd0a0@web.de>
In-Reply-To: <CACsJy8AAtV5KJHBqWvnYb3Mw9CVzEdG3M-UJA+jd5MR5e-UMsA@mail.gmail.com>

Am 24.04.2017 um 12:39 schrieb Duy Nguyen:
> BTW, I ran t7009 with valgrind and it reported this. Is it something
> we should be worried about? I vaguely recall you're doing something
> with prio-queue...
> 
> ==4246== Source and destination overlap in memcpy(0x5952990, 0x5952990, 16)
> ==4246==    at 0x4C2EACD: memcpy@@GLIBC_2.14 (in
> /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==4246==    by 0x545D05: swap (prio-queue.c:15)
> ==4246==    by 0x545D72: prio_queue_reverse (prio-queue.c:25)
> ==4246==    by 0x4CBC0C: sort_in_topological_order (commit.c:723)
> ==4246==    by 0x574C97: prepare_revision_walk (revision.c:2858)
> ==4246==    by 0x48A2BA: cmd_rev_list (rev-list.c:385)
> ==4246==    by 0x405A6F: run_builtin (git.c:371)
> ==4246==    by 0x405CDC: handle_builtin (git.c:572)
> ==4246==    by 0x405E51: run_argv (git.c:624)
> ==4246==    by 0x405FF3: cmd_main (git.c:701)
> ==4246==    by 0x4A48CE: main (common-main.c:43)

I can only get gcc and clang to call memcpy instead of inlining it by
specifying -fno-builtin.  Do you use that option?  If yes, why?  (Just
curious.)

But I can't get Valgrind to report overlapping (nicely explained in
http://valgrind.org/docs/manual/mc-manual.html#mc-manual.overlap, by
the way), not for t7009 and not for the short test program at the
bottom.  Do you set flags in GIT_VALGRIND_OPTIONS or use a special
version of Valgrind?  I use valgrind-3.12.0.SVN from Debian testing.

Thanks,
René


/* Compile with -fno-builtin. */
#include <string.h>
int main(void) {int i = 1; memcpy(&i, &i, sizeof(i)); return i;}