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authorAdhemerval Zanella <azanella@linux.vnet.ibm.com>2013-06-12 10:21:22 -0500
committerAdhemerval Zanella <azanella@linux.vnet.ibm.com>2013-06-12 10:21:22 -0500
commit6a97b62a5b4f18aea849d6f4d8de58d1469d2521 (patch)
tree0fdb35cb468bdb040fd3a1f01b4ddcc70b0f30dd /sysdeps
parent94f2c076692a5a4beaa9a85eb10dbe4d891acb1e (diff)
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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.
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/generic/symbol-hacks.h7
-rw-r--r--sysdeps/wordsize-32/symbol-hacks.h2
2 files changed, 8 insertions, 1 deletions
diff --git a/sysdeps/generic/symbol-hacks.h b/sysdeps/generic/symbol-hacks.h
index bc7b4c4441..9eaf014ff2 100644
--- 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 52ac5c1e0a..202a8070de 100644
--- 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