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author | Ivan Maidanski <ivmai@mail.ru> | 2012-03-07 19:12:49 +0400 |
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committer | Ivan Maidanski <ivmai@mail.ru> | 2012-03-07 19:37:14 +0400 |
commit | aafe40ab62e78405cfafb5549fb4d11e01956190 (patch) | |
tree | e8680ef6806c862e9c62df16bcd4036d254f6e53 | |
parent | 07bc4d0ab7cdaa1ce73a32437bc6bc6e41c57dcb (diff) | |
download | libatomic_ops-aafe40ab62e78405cfafb5549fb4d11e01956190.tar.gz |
Fix AO_compare_double_and_swap_double_full for gcc/x86 (PIC mode)
* src/atomic_ops/sysdeps/gcc/x86.h
(AO_compare_double_and_swap_double_full): Use EDI register for
"new_val1" argument instead of a memory operand and use XCHG assembler
instruction instead of push/pop in case of PIC mode (to workaround
a bug in GCC 4.6.1); update the comment.
-rw-r--r-- | src/atomic_ops/sysdeps/gcc/x86.h | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/src/atomic_ops/sysdeps/gcc/x86.h b/src/atomic_ops/sysdeps/gcc/x86.h index f3560b0..df02a46 100644 --- a/src/atomic_ops/sysdeps/gcc/x86.h +++ b/src/atomic_ops/sysdeps/gcc/x86.h @@ -141,13 +141,16 @@ AO_compare_double_and_swap_double_full(volatile AO_double_t *addr, /* If PIC is turned on, we can't use %ebx as it is reserved for the GOT pointer. We can save and restore %ebx because GCC won't be using it for anything else (such as any of the m operands) */ - __asm__ __volatile__("pushl %%ebx;" /* save ebx used for PIC GOT ptr */ - "movl %6,%%ebx;" /* move new_val1 to %ebx */ + /* We use %edi (for new_val1) instead of a memory operand and swap */ + /* instruction instead of push/pop because some GCC releases have */ + /* a bug in processing memory operands (if address base is %esp) in */ + /* the inline assembly after push. */ + __asm__ __volatile__("xchg %%ebx,%6;" /* swap GOT ptr and new_val1 */ "lock; cmpxchg8b %0; setz %1;" - "pop %%ebx;" /* restore %ebx */ + "xchg %%ebx,%6;" /* restore ebx and edi */ : "=m"(*addr), "=a"(result) : "m"(*addr), "d" (old_val2), "a" (old_val1), - "c" (new_val2), "m" (new_val1) : "memory"); + "c" (new_val2), "D" (new_val1) : "memory"); #else /* We can't just do the same thing in non-PIC mode, because GCC * might be using %ebx as the memory operand. We could have ifdef'd |