From: ludo@gnu.org (Ludovic Courtès)
To: 30820@debbugs.gnu.org
Cc: 30395@debbugs.gnu.org
Subject: bug#30395: bug#30820: Chunked store references in compiled code break grafting (again)
Date: Fri, 16 Mar 2018 09:54:31 +0100 [thread overview]
Message-ID: <87in9wxuwo.fsf@gnu.org> (raw)
In-Reply-To: <87efkm7eov.fsf@gnu.org> ("Ludovic \=\?utf-8\?Q\?Court\=C3\=A8s\=22'\?\= \=\?utf-8\?Q\?s\?\= message of "Wed, 14 Mar 2018 18:24:48 +0100")
ludo@gnu.org (Ludovic Courtès) skribis:
> void foo (char *x, char *y)
> {
> /* MEMCPY (x, str, sizeof str); */
> MEMCPY (y, "this is a literal /gnu/store string", 35);
> }
This was not a correct example because “/gnu/store” must be followed by
at least 34 chars for the patch to work. And indeed, it does work in
this case:
--8<---------------cut here---------------start------------->8---
$ cat strmov.c
#define _GNU_SOURCE
#include <string.h>
static const char str[] = "MEMpCPY /gnu/store/THIS IS A LONG STRING, A VERY, VERY, VERY LOOOOONG STRING";
extern char *p, *q;
#ifndef MEMCPY
# define MEMCPY memcpy
#endif
void foo (char *x, char *y)
{
/* MEMCPY (x, str, sizeof str); */
MEMCPY (y, "this is a literal /gnu/store/eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee string", 35);
}
$ guix environment --ad-hoc gcc-toolchain@5 -C -- gcc -O2 -c strmov.c
$ objdump -S strmov.o |grep movabs
--8<---------------cut here---------------end--------------->8---
So the real issue is this:
> The second issue is that the patch only ever worked with literal
> strings. It does not “see” strings in constant arrays like the ‘str’
> array in the example above.
Ludo’.
next prev parent reply other threads:[~2018-03-16 8:55 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-14 15:47 bug#30820: Chunked store references in compiled code break grafting (again) Ludovic Courtès
2018-03-14 17:24 ` Ludovic Courtès
2018-03-16 8:54 ` Ludovic Courtès [this message]
2018-03-20 23:07 ` bug#30395: " Ludovic Courtès
2018-03-21 6:39 ` Ricardo Wurmus
2018-03-21 20:59 ` Ludovic Courtès
2018-03-19 21:22 ` Danny Milosavljevic
2018-03-19 22:29 ` Ludovic Courtès
2018-03-19 19:05 ` Mark H Weaver
2018-03-19 19:16 ` Mark H Weaver
2018-03-19 21:34 ` Danny Milosavljevic
2018-03-19 22:27 ` Ludovic Courtès
2018-03-20 1:04 ` Mark H Weaver
2018-03-20 8:50 ` Ludovic Courtès
2018-03-19 22:34 ` Ludovic Courtès
2018-03-20 0:52 ` Mark H Weaver
2018-03-20 8:56 ` Ludovic Courtès
2018-03-21 4:17 ` Mark H Weaver
2018-03-21 5:43 ` Mark H Weaver
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