From 6a97b62a5b4f18aea849d6f4d8de58d1469d2521 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Wed, 12 Jun 2013 10:21:22 -0500 Subject: [PATCH] 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. --- ChangeLog | 8 ++++++++ sysdeps/generic/symbol-hacks.h | 7 ++++++- sysdeps/wordsize-32/symbol-hacks.h | 2 ++ 3 files changed, 16 insertions(+), 1 deletion(-) diff --git a/ChangeLog b/ChangeLog index d38c96a9e8..d08f0a6b2e 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,11 @@ +2013-06-11 Adhemerval Zanella + + [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 * math/bug-nextafter.c: Include . 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 . */ +#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