Hello Andrew ,
Thanks for the response :
also wanted you to know that the problem is only for a 64 bit value ;
it compiles fine for a 32 bit int.
Thanks .
Preeti
On Wed, Jul 7, 2010 at 8:43 AM, Andrew Haley <aph@xxxxxxxxxx> wrote:
> On 07/07/2010 04:26 PM, Preeti Sharma wrote:
>> I am trying to use __sync_fetch_and_add with type as "long long" .
>>
>> This gives me the link error :
>> undefined reference to `__sync_fetch_and_add_8'
>>
>> This compiles for a "int " type though. I am using the the gcc option
>> -march=i686
>>
>> Is it possible to do a 64 bit integer operation atomically with the
>> __sync .. builtin functions ?
>
> Works for me:
>
> long long a;
>
> t()
> {
> __sync_fetch_and_add(&a, 1);
> }
>
> $ gcc -S t.c -m32 -march=i686 -O2
>
> .file "t.c"
> .text
> .p2align 4,,15
> .globl t
> .type t, @function
> t:
> pushl %ebp
> movl %esp, %ebp
> subl $12, %esp
> movl %ebx, (%esp)
> movl %esi, 4(%esp)
> movl %edi, 8(%esp)
> movl a, %eax
> movl a+4, %edx
> .L2:
> movl %eax, %esi
> movl %edx, %edi
> addl $1, %esi
> adcl $0, %edi
> movl %esi, %ebx
> movl %edi, %ecx
> lock cmpxchg8b a
> jne .L2
> movl (%esp), %ebx
> movl 4(%esp), %esi
> movl 8(%esp), %edi
> movl %ebp, %esp
> popl %ebp
> ret
> .size t, .-t
> .comm a,8,8
> .ident "GCC: (GNU) 4.4.3 20100127 (Red Hat 4.4.3-4)"
> .section .note.GNU-stack,"",@progbits
>
>
