Re: Better LWLocks with compare-and-swap (9.4)

On 20.05.2013 23:11, Alvaro Herrera wrote:
>> diff --git a/configure.in b/configure.in
>> index 4ea5699..ff8470e 100644
>> --- a/configure.in
>> +++ b/configure.in
>> @@ -1445,17 +1445,6 @@ fi
>>   AC_CHECK_FUNCS([strtoll strtoq], [break])
>>   AC_CHECK_FUNCS([strtoull strtouq], [break])
>>
>> -AC_CACHE_CHECK([for builtin locking functions], pgac_cv_gcc_int_atomics,
>> -[AC_TRY_LINK([],
>> -  [int lock = 0;
>> -   __sync_lock_test_and_set(&lock, 1);
>> -   __sync_lock_release(&lock);],
>> -  [pgac_cv_gcc_int_atomics="yes"],
>> -  [pgac_cv_gcc_int_atomics="no"])])
>> -if test x"$pgac_cv_gcc_int_atomics" = x"yes"; then
>> -  AC_DEFINE(HAVE_GCC_INT_ATOMICS, 1, [Define to 1 if you have __sync_lock_test_and_set(int *) and friends.])
>> -fi
>> -
>
> Careful here --- s_lock.h has some code conditional on
> HAVE_GCC_INT_ATOMICS which your patch is not touching, yet it is
> removing the definition, unless I'm misreading.

Thanks, good catch. I renamed HAVE_GCC_INT_ATOMICS to 
HAVE_GCC_INT_TEST_AND_SET because "atomics" seems too generic when we 
also test for __sync_val_compare_and_swap(p, oldval, newval).

- Heikki