Fix unsafe compiler optimization

GCC 4.8 enables -ftree-loop-distribute-patterns at -O3 by default and
this optimization may transform loops into memset/memmove calls. Without
proper handling this may generate unexpected PLT calls on GLIBC.
This patch fixes by create memset/memmove alias to internal GLIBC
__GI_memset/__GI_memmove symbols.

diff --git a/ChangeLog b/ChangeLog
index d38c96a..d08f0a6 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2013-06-11  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
+
+       [BZ #15605]
+       * sysdeps/generic/symbol-hacks.h: Add workaround for memset/memmove calls
+       generated by the compiler on loop optimizations.
+       * sysdeps/wordsize-32/symbol-hacks.h: Include next symbol-hacks.h for
+       general definitions.
+
 2013-06-12  Joseph Myers  <joseph@codesourcery.com>
 
        * math/bug-nextafter.c: Include <math-tests.h>.

diff --git a/sysdeps/generic/symbol-hacks.h b/sysdeps/generic/symbol-hacks.h
index bc7b4c4..9eaf014 100644 (file)
--- a/sysdeps/generic/symbol-hacks.h
+++ b/sysdeps/generic/symbol-hacks.h
@@ -1 +1,6 @@
-/* Fortunately nothing to do.  */
+/* Some compiler optimizations may transform loops into memset/memmove
+   calls and without proper declaration it may generate PLT calls.  */
+#if !defined __ASSEMBLER__ && !defined NOT_IN_libc && defined SHARED
+asm ("memmove = __GI_memmove");
+asm ("memset = __GI_memset");
+#endif

diff --git a/sysdeps/wordsize-32/symbol-hacks.h b/sysdeps/wordsize-32/symbol-hacks.h
index 52ac5c1..202a807 100644 (file)
--- a/sysdeps/wordsize-32/symbol-hacks.h
+++ b/sysdeps/wordsize-32/symbol-hacks.h
@@ -16,6 +16,8 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#include_next "symbol-hacks.h"
+
 /* A very dirty trick: gcc emits references to __divdi3, __udivdi3,
    __moddi3, and __umoddi3.  These functions are exported and
    therefore we get PLTs.  Unnecessarily so.  Changing gcc is a big