From: hjl@lucon.org (H.J. Lu)
To: jfc@mit.edu (John Carr)
Cc: egcs@cygnus.com, drepper@cygnus.com (Ulrich Drepper)
Subject: Re: An optimization bug in egcs 1.0.2?
Date: Mon, 23 Mar 1998 19:24:00 -0000 [thread overview]
Message-ID: <m0yHHxm-00058JC@ocean.lucon.org> (raw)
In-Reply-To: <199803240043.TAA18518@jfc.>
>
>
> The code calls memcpy with overlapping objects. That is undefined in
> ANSI C; use memmove instead. (It also subtracts pointers to void so
> the authors presumably didn't care about ANSI C, but the misuse of
> memcpy is a real problem.)
It is from the dynamic linker in glibc 2. memcpy is safe there.
memcpy is used for optimization.
>
> There may also be a bug in egcs in addition to the bug in the code.
> Can you generate a standalone test case with annotated assembly code?
I don't think there is a question on egcs. I don't want to spend
any more time on it since it has been fixed in glibc 2. If you really
want to look into it, I can do it when I find time.
>
>
> > if (imap->l_global)
> > {
> > /* This object is in the global scope list. Remove it. */
> > struct link_map **tail = _dl_global_scope_end;
> > do
> > --tail;
> > while (*tail != imap);
> > --_dl_global_scope_end;
> > memcpy (tail, tail + 1,
> > (void *) _dl_global_scope_end - (void *) tail);
> > _dl_global_scope_end[0] = NULL;
> > _dl_global_scope_end[1] = NULL;
> > }
>
--
H.J. Lu (hjl@gnu.org)
next prev parent reply other threads:[~1998-03-23 19:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-03-23 15:11 H.J. Lu
1998-03-23 19:24 ` John Carr
1998-03-23 19:24 ` H.J. Lu [this message]
1998-03-23 23:47 ` Jeffrey A Law
1998-03-24 11:16 ` Richard Henderson
1998-03-24 8:29 ` H.J. Lu
1998-03-24 9:27 ` H.J. Lu
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