On 02/14/17 19:50, Joe Savage wrote:
>> I can not compile your code with clang-3.8, gcc works well. But looks
>> like clang does not support libatomic so -latomic -mcx16 does not work
>> for functions ending on _16"
>> ./test.c:(.text+0x61): undefined reference to `__atomic_load_16'
>> ./test.c:(.text+0x92): undefined reference to `__atomic_store_16'
>> ./test.c:(.text+0xcb): undefined reference to `__atomic_compare_exchange_16'
>>
>> but clang compiles well for n functions.
>> __atomic_com__atomic_compare_exchange_n(pare_exchange_n(
>>
>>
>> You saw that I send m4 checks for test compilations which worked well
>> with gcc. Now we need to fix clang before merging it.
>>
>> I reproduce it with that code:
>>
>> int main() {
>> unsigned __int128 x = 0, y = 0;
>> y = __atomic_load_16(&x, 0);
>> __atomic_store_16(&x, y, 0);
>> __atomic_compare_exchange_16(&x, &y, x, 0, 0, 0);
>> return 0;
>> }
>>
>> Do you have any ideas?
>
> With regards to the code snippet that reproduces the issue, you shouldn't be
> using the "*_16" versions of the atomic built-ins. On changing the code to
> take this into consideration, clang compiles and links just fine for me:
>
> int main(void)
> {
> unsigned __int128 x = 0, y = 0;
> y = __atomic_load_n(&x, 0);
> __atomic_store_n(&x, y, 0);
> __atomic_compare_exchange_n(&x, &y, x, 0, 0, 0);
>
> return 0;
> }
>
> The code in the example directory already does this, though, so this
> shouldn't be the problem. My guess is that something needs to be adjusted
> within the project's build infrastructure, as "__atomic_compare_exchange_n"
> works perfectly fine within e.g. platform/linux-generic/pktio/ring.c.
>
ok, it looks like in case of clang we need to pass -mcx16 and no need to
pass libatomic. I will check if I do that in my patch.
I compiled it also:
root:22:37 /tmp $cat > test2.c
int main(void)
{
unsigned __int128 x = 0, y = 0;
y = __atomic_load_n(&x, 0);
__atomic_store_n(&x, y, 0);
__atomic_compare_exchange_n(&x, &y, x, 0, 0, 0);
return 0;
}
root:22:37 /tmp $clang-3.8 test2.c
/tmp/test2-d3255f.o: In function `main':
test2.c:(.text+0x51): undefined reference to
`__sync_val_compare_and_swap_16'
test2.c:(.text+0x75): undefined reference to `__sync_lock_test_and_set_16'
test2.c:(.text+0xcd): undefined reference to
`__sync_val_compare_and_swap_16'
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
root:22:37 /tmp $clang-3.8 test2.c -latomic
/usr/bin/ld: cannot find -latomic
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
root:22:38 /tmp $clang-3.8 test2.c -mcx16
root:22:38 /tmp $
