On 12 December 2014 at 16:59, Mike Holmes <mike.hol...@linaro.org> wrote:
>
>
> On 12 December 2014 at 10:51, Maxim Uvarov <maxim.uva...@linaro.org> wrote:
>>
>> On 12/12/2014 06:47 PM, Taras Kondratiuk wrote:
>>>
>>> On 12/12/2014 05:03 PM, Maxim Uvarov wrote:
>>>>
>>>> Odp atomic operations based on compiler build-ins. Make
>>>> sure that compiler supports such operation at configure
>>>> stage.
>>>
>>> This check should be limited to platforms that use gcc atomics.
>>
>> Do we have such platforms?
>
>
> __OCTEON__ directly swappes out gcc, infact that pre processor switch
> affects other files in linux-generic too.
>
> static inline uint32_t odp_atomic_fetch_inc_u32(odp_atomic_u32_t *atom)
> {
> #if defined __OCTEON__
>>-------uint32_t ret;
>>-------__asm__ __volatile__ ("syncws");
>>-------__asm__ __volatile__ ("lai %0,(%2)" : "=r" (ret), "+m" (atom) :
>>------->------->------- "r" (atom));
>>-------return ret;
> #else
>>-------return __atomic_fetch_add(&atom->v, 1, __ATOMIC_RELAXED);
> #endif
> }
This is an OCTEON-special for just one function. I didn't want to
remove it. But I am not sure it is actually needed. Shouldn't the
compiler be able to generate the appropriate OCTEON-specific
instructions (e.g. laa(d), saa(d), lai(d), lad(d) etc), gcc has
supported OCTEON since version 4.4? Also I don't understand the reason
for the syncw *before* the lai (load-atomic-increment) but perhaps the
load-atomic instructions (which shouldn't linger in the write buffer
like stores) need to be treated differently.
I think this OCTEON-fix should either be removed or there should be
specials for most if not all of the functions in odp_atomic.h
>
>
>>
>>
>>
>> Maxim.
>>
>>
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>
>
>
> --
> Mike Holmes
> Linaro Sr Technical Manager
> LNG - ODP
>
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>
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