Re: [HACKERS] Fix performance of generic atomics

Sokolov Yura <funny.falcon@postgrespro.ru> writes:
@@ -382,12 +358,8 @@ static inline uint64pg_atomic_fetch_and_u64_impl(volatile pg_atomic_uint64 *ptr, uint64 and_){
uint64old;
 
-    while (true)
-    {
-        old = pg_atomic_read_u64_impl(ptr);
-        if (pg_atomic_compare_exchange_u64_impl(ptr, &old, old & and_))
-            break;
-    }
+    old = pg_atomic_read_u64_impl(ptr);
+    while (!pg_atomic_compare_exchange_u64_impl(ptr, &old, old & and_));    return old;}#endif

FWIW, I do not think that writing the loops like that is good style.
It looks like a typo and will confuse readers.  You could perhaps
write the same code with better formatting, eg
while (!pg_atomic_compare_exchange_u64_impl(ptr, &old, old & and_))    /* skip */ ;

but why not leave the formulation with while(true) and a break alone?

(I take no position on whether moving the read of "old" outside the
loop is a valid optimization.)
        regards, tom lane