Re: [dpdk-dev] [PATCH v6] eal/x86: add 128-bit atomic compare exchange

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 4/4/2019 1:18 PM, Thomas Monjalon wrote:
> 04/04/2019 14:14, Eads, Gage:
>> From: Thomas Monjalon [mailto:thomas@monjalon.net]
>>> 04/04/2019 14:08, Thomas Monjalon:
>>>> 04/04/2019 13:47, Ferruh Yigit:
>>>>> .../dpdk/x86_64-native-linuxapp-gcc/include/rte_atomic_64.h:223:3:
>>>>> error: ISO C does not support ‘__int128’ types [-Werror=pedantic]
>>>>
>>>> We can try this kind of workaround (disable pedantic locally):
>>>>
>>> https://github.com/HowardHinnant/date/pull/38/commits/177032852d5b46
>>> 14
>>>> 112ca1ab3ef42d6b41824816
>>>
>>> Or better:
>>> __extension__ typedef __int128 int128;
>>>
>>
>> Taking that one step further -- RTE_STD_C11 evaluates to __extension__ (when the STD C version is sufficiently old).
> 
> I don't think __int128 is part of C11. Is it?
> 
> Ferruh, I cannot reproduce the compiler error. What is your compiler?
> Please, could you test this patch?

It is gcc [1]. Sure will test it.

[1]
gcc (GCC) 8.3.1 20190223 (Red Hat 8.3.1-2)

> 
> --- a/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h
> +++ b/lib/librte_eal/common/include/arch/x86/rte_atomic_64.h
> @@ -220,7 +220,7 @@ typedef struct {
>         RTE_STD_C11
>         union {
>                 uint64_t val[2];
> -               __int128 int128;
> +               __extension__ __int128 int128;
>         };
>  } __rte_aligned(16) rte_int128_t;
> 
> 
>