help with __sync for "long long" types

[Preeti Sharma]

Thanks Andrew,

Could you tell me which version works for you ?

Thanks

Preeti.

On Wed, Jul 7, 2010 at 9:10 AM, Andrew Haley <aph@redhat.com> wrote:
> On 07/07/2010 05:00 PM, Preeti Sharma wrote:
>
>> 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.
>
> Yes, I get the same problem with 4.1.2.
>
> Maybe you should upgrade.
>
> Andrew.
>
>
>> On Wed, Jul 7, 2010 at 8:43 AM, Andrew Haley <aph@redhat.com> 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
>>>
>>>
>
>