On 13/11/18 22:59 +0000, Jonathan Wakely wrote:
* src/c++17/memory_resource.cc (bitset::find_first_unset()): Remove
unused function.
(bitset::get_first_unset()): Remove loop, if there's are unset bits
then _M_next_word refers to the first one and there's no need to loop.
(_Pool::_Pool(size_t, size_t), _Pool::block_size()): Remove dead code.
size_type get_first_unset() noexcept
{
- for (size_type i = _M_next_word; i < nwords(); ++i)
+ if (_M_next_word < nwords())
{
- const size_type n = std::__countr_one(_M_words[i]);
+ const size_type n = std::__countr_one(_M_words[_M_next_word]);
if (n < bits_per_word)
{
const word bit = word(1) << n;
- _M_words[i] |= bit;
- if (i == _M_next_word)
+ _M_words[_M_next_word] |= bit;
+ const size_t res = (_M_next_word * bits_per_word) + n;
+ if (n == (bits_per_word - 1))
update_next_word();
- return (i * bits_per_word) + n;
+ return res;
}
}
return size_type(-1);
I'm not sure why, but this version seems to perform measurably worse.
I'll investigate, and maybe revert the change.
