===================================================================
@@ -300,23 +300,30 @@
{
// Optimize lookups involving the first elements of __prime_list.
// (useful to speed-up, eg, constructors)
- static const unsigned long __fast_bkt[12]
+ static const unsigned char __fast_bkt[12]
= { 2, 2, 2, 3, 5, 5, 7, 7, 11, 11, 11, 11 };
+ if (__n <= 11)
+ {
+ _M_prev_resize = 0;
+ _M_next_resize
+ = __builtin_ceil(__fast_bkt[__n] * (long double)_M_max_load_factor);
+ return __fast_bkt[__n];
+ }
+
const unsigned long* __p
- = __n <= 11 ? __fast_bkt + __n
- : std::lower_bound(__prime_list + 5,
- __prime_list + _S_n_primes, __n);
+ = std::lower_bound(__prime_list + 5, __prime_list + _S_n_primes, __n);
- _M_prev_resize = __builtin_floor(*__p * (long double)_M_max_load_factor);
- if (__p != __fast_bkt)
- _M_prev_resize = std::min(_M_prev_resize,
- static_cast<std::size_t>(*(__p - 1)));
- // Lets guaranty a minimal grow step of 11:
+ // Shrink will take place only if the number of elements is small enough
+ // so that the prime number 2 steps before __p is large enough to still
+ // conform to the max load factor:
+ _M_prev_resize
+ = __builtin_floor(*(__p - 2) * (long double)_M_max_load_factor);
+
+ // Let's guaranty that a minimal grow step of 11 is used
if (*__p - __n < 11)
- __p = std::lower_bound(__prime_list + 5,
- __prime_list + _S_n_primes, __n + 11);
- _M_next_resize = __builtin_floor(*__p * (long double)_M_max_load_factor);
+ __p = std::lower_bound(__p, __prime_list + _S_n_primes, __n + 11);
+ _M_next_resize = __builtin_ceil(*__p * (long double)_M_max_load_factor);
return *__p;
}