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GNU C Library master sources branch master updated. glibc-2.26-575-g8e57c94
- From: hjl at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 15 Oct 2017 15:17:37 -0000
- Subject: GNU C Library master sources branch master updated. glibc-2.26-575-g8e57c94
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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=8e57c9432a2b68c8a1e7f4df28f0e8c7acc04753
commit 8e57c9432a2b68c8a1e7f4df28f0e8c7acc04753
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Sun Oct 15 08:16:26 2017 -0700
Silence -O3 -Wall warning in malloc/hooks.c with GCC 7 [BZ #22052]
realloc_check has
unsigned char *magic_p;
...
__libc_lock_lock (main_arena.mutex);
const mchunkptr oldp = mem2chunk_check (oldmem, &magic_p);
__libc_lock_unlock (main_arena.mutex);
if (!oldp)
malloc_printerr ("realloc(): invalid pointer");
...
if (newmem == NULL)
*magic_p ^= 0xFF;
with
static void malloc_printerr(const char *str) __attribute__ ((noreturn));
GCC 7 -O3 warns
hooks.c: In function â??realloc_checkâ??:
hooks.c:352:14: error: â??magic_pâ?? may be used uninitialized in this function [-Werror=maybe-uninitialized]
*magic_p ^= 0xFF;
due to the GCC bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82090
This patch silences GCC 7 by using DIAG_IGNORE_NEEDS_COMMENT.
[BZ #22052]
* malloc/hooks.c (realloc_check): Use DIAG_IGNORE_NEEDS_COMMENT
to silence -O3 -Wall warning with GCC 7.
diff --git a/ChangeLog b/ChangeLog
index eed7450..17fbe55 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-10-15 H.J. Lu <hongjiu.lu@intel.com>
+
+ [BZ #22052]
+ * malloc/hooks.c (realloc_check): Use DIAG_IGNORE_NEEDS_COMMENT
+ to silence -O3 -Wall warning with GCC 7.
+
2017-10-14 H.J. Lu <hongjiu.lu@intel.com>
* Makeconfig (+link-static-before-libc): Use the first of
diff --git a/malloc/hooks.c b/malloc/hooks.c
index 01be076..17d8907 100644
--- a/malloc/hooks.c
+++ b/malloc/hooks.c
@@ -345,11 +345,18 @@ realloc_check (void *oldmem, size_t bytes, const void *caller)
newmem = _int_realloc (&main_arena, oldp, oldsize, nb);
}
+ DIAG_PUSH_NEEDS_COMMENT;
+#if __GNUC_PREREQ (7, 0)
+ /* GCC 7 warns about magic_p may be used uninitialized. But we never
+ reach here if magic_p is uninitialized. */
+ DIAG_IGNORE_NEEDS_COMMENT (7, "-Wmaybe-uninitialized");
+#endif
/* mem2chunk_check changed the magic byte in the old chunk.
If newmem is NULL, then the old chunk will still be used though,
so we need to invert that change here. */
if (newmem == NULL)
*magic_p ^= 0xFF;
+ DIAG_POP_NEEDS_COMMENT;
__libc_lock_unlock (main_arena.mutex);
-----------------------------------------------------------------------
Summary of changes:
ChangeLog | 6 ++++++
malloc/hooks.c | 7 +++++++
2 files changed, 13 insertions(+), 0 deletions(-)
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