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Direct implementation of segmented_fill[_n], calling segmented_generate[_n] can be suboptimal in some compilers.
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Ion Gaztañaga
@@ -21,19 +21,113 @@
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#include <boost/container/detail/config_begin.hpp>
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#include <boost/container/detail/workaround.hpp>
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#include <boost/container/experimental/segmented_iterator_traits.hpp>
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#include <boost/container/experimental/segmented_generate.hpp>
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#include <boost/container/detail/iterator.hpp>
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#include <boost/container/experimental/segmented_fill_n.hpp>
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namespace boost {
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namespace container {
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template <class FwdIt, class Sent, class T>
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void segmented_fill(FwdIt first, Sent last, const T& value);
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namespace detail_algo {
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#if defined(BOOST_CONTAINER_SEGMENTED_LOOP_UNROLLING)
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template <class RAIter, class T>
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void segmented_fill_range
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(RAIter first, RAIter last, const T& value, const non_segmented_iterator_tag &, const std::random_access_iterator_tag &)
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{
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typedef typename iterator_traits<RAIter>::difference_type difference_type;
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difference_type n = last - first;
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while(n >= difference_type(4)) {
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*first = value; ++first;
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*first = value; ++first;
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*first = value; ++first;
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*first = value; ++first;
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n -= 4;
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}
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switch(n) {
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case 3:
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*first = value; ++first;
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BOOST_FALLTHROUGH;
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case 2:
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*first = value; ++first;
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BOOST_FALLTHROUGH;
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case 1:
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*first = value;
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BOOST_FALLTHROUGH;
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default:
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break;
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}
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}
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#endif //BOOST_CONTAINER_SEGMENTED_LOOP_UNROLLING
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template <class FwdIt, class Sent, class T, class Tag, class Cat>
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BOOST_CONTAINER_FORCEINLINE typename algo_enable_if_c<
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!Tag::value || is_sentinel<Sent, FwdIt>::value>::type
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segmented_fill_range(FwdIt first, Sent last, const T& value, Tag, Cat)
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{
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for(; first != last; ++first)
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*first = value;
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}
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template <class SegIter, class T, class Cat>
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void segmented_fill_range
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(SegIter first, SegIter last, const T& value, segmented_iterator_tag, Cat)
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{
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typedef segmented_iterator_traits<SegIter> traits;
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typedef typename traits::local_iterator local_iterator;
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typedef typename traits::segment_iterator segment_iterator;
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typedef typename segmented_iterator_traits<local_iterator>::is_segmented_iterator is_local_seg_t;
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typedef typename iterator_traits<local_iterator>::iterator_category local_cat_t;
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segment_iterator sfirst = traits::segment(first);
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segment_iterator slast = traits::segment(last);
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if(sfirst == slast) {
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(segmented_fill_range)(traits::local(first), traits::local(last), value, is_local_seg_t(), local_cat_t());
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}
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else {
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(segmented_fill_range)(traits::local(first), traits::end(sfirst), value, is_local_seg_t(), local_cat_t());
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for(++sfirst; sfirst != slast; ++sfirst)
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(segmented_fill_range)(traits::begin(sfirst), traits::end(sfirst), value, is_local_seg_t(), local_cat_t());
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(segmented_fill_range)(traits::begin(sfirst), traits::local(last), value, is_local_seg_t(), local_cat_t());
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}
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}
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template <class FwdIt, class T>
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BOOST_CONTAINER_FORCEINLINE
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void segmented_fill_dispatch(FwdIt first, FwdIt last, const T& value, const std::random_access_iterator_tag &)
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{
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(segmented_fill_n)(first, last - first, value);
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}
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template <class FwdIt, class Sent, class T, class Cat>
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BOOST_CONTAINER_FORCEINLINE
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void segmented_fill_dispatch(FwdIt first, Sent last, const T& value, const Cat &)
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{
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typedef segmented_iterator_traits<FwdIt> traits;
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(segmented_fill_range)(first, last, value, typename traits::is_segmented_iterator(), Cat());
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}
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} // namespace detail_algo
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//! Assigns \c value to every element in [first, last).
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//! When \c Iter is a segmented iterator, exploits segmentation
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//! to reduce per-element overhead.
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//! When \c Sent is the same type as \c FwdIt and the iterator
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//! category is random access, derives to \c segmented_fill_n.
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template <class FwdIt, class Sent, class T>
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BOOST_CONTAINER_FORCEINLINE
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void segmented_fill(FwdIt first, Sent last, const T& value)
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{
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(segmented_generate)(first, last, detail_algo::constref_generator<T>(value));
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detail_algo::segmented_fill_dispatch(first, last, value, typename iterator_traits<FwdIt>::iterator_category());
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}
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} // namespace container
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@@ -21,11 +21,141 @@
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#include <boost/container/detail/config_begin.hpp>
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#include <boost/container/detail/workaround.hpp>
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#include <boost/container/experimental/segmented_iterator_traits.hpp>
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#include <boost/container/experimental/segmented_generate_n.hpp>
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#include <boost/container/detail/iterators.hpp>
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#include <boost/container/detail/std_fwd.hpp>
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namespace boost {
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namespace container {
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template <class FwdIt, class Size, class T>
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FwdIt segmented_fill_n(FwdIt first, Size count, const T& value);
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namespace detail_algo {
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template <class OutIter, class Size, class T>
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OutIter fill_n_scan_non_segmented(OutIter first, OutIter last, Size& count, const T& value, const std::random_access_iterator_tag &)
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{
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std::size_t range_sz = static_cast<std::size_t>(last - first);
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const Size local_count = (std::size_t)count < range_sz ? count : (Size)range_sz;
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#if defined(BOOST_CONTAINER_SEGMENTED_LOOP_UNROLLING)
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Size cnt = local_count;
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while(cnt >= Size(4)) {
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*first = value; ++first;
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*first = value; ++first;
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*first = value; ++first;
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*first = value; ++first;
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cnt -= Size(4);
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}
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switch(cnt) {
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case 3:
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*first = value; ++first;
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BOOST_FALLTHROUGH;
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case 2:
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*first = value; ++first;
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BOOST_FALLTHROUGH;
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case 1:
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*first = value; ++first;
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BOOST_FALLTHROUGH;
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default:
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break;
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}
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#else
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for(Size cnt = local_count; cnt; ++first, --cnt)
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*first = value;
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#endif
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count -= local_count;
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return first;
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}
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template <class OutIter, class Size, class T, class Tag>
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OutIter fill_n_scan_non_segmented(OutIter first, OutIter last, Size& count, const T& value, Tag)
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{
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Size local_count = count;
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for (; local_count > 0 && first != last; ++first, --local_count)
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*first = value;
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count = local_count;
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return first;
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}
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template <class OutIter, class Size, class T>
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BOOST_CONTAINER_FORCEINLINE
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OutIter fill_n_scan(OutIter first, OutIter last, Size& count, const T& value, non_segmented_iterator_tag)
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{
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return (fill_n_scan_non_segmented)(first, last, count, value, typename iterator_traits<OutIter>::iterator_category());
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}
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template <class SegIt, class Size, class T>
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SegIt fill_n_scan(SegIt first, SegIt last, Size& count, const T& value, segmented_iterator_tag)
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{
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typedef segmented_iterator_traits<SegIt> traits;
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typedef typename traits::local_iterator local_iterator;
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typedef typename traits::segment_iterator segment_iterator;
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typedef typename segmented_iterator_traits<local_iterator>::is_segmented_iterator is_local_seg_t;
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segment_iterator scur = traits::segment(first);
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segment_iterator const slast = traits::segment(last);
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if(scur == slast) {
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const local_iterator ll = traits::local(last);
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const local_iterator r = (fill_n_scan)(traits::local(first), ll, count, value, is_local_seg_t());
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return (r != ll) ? traits::compose(scur, r) : last;
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}
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else {
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local_iterator r = fill_n_scan(traits::local(first), traits::end(scur), count, value, is_local_seg_t());
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if (!count)
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return traits::compose(scur, r);
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for (++scur; scur != slast; ++scur) {
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r = fill_n_scan(traits::begin(scur), traits::end(scur), count, value, is_local_seg_t());
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if (!count)
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return traits::compose(scur, r);
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}
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const local_iterator ll = traits::local(last);
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r = fill_n_scan(traits::begin(slast), ll, count, value, is_local_seg_t());
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return (r != ll) ? traits::compose(scur, r) : last;
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}
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}
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template <class SegIter, class Size, class T>
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SegIter segmented_fill_n_ref
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(SegIter first, Size count, const T& value, segmented_iterator_tag)
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{
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typedef segmented_iterator_traits<SegIter> traits;
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typedef typename traits::local_iterator local_iterator;
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typedef typename traits::segment_iterator segment_iterator;
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typedef typename segmented_iterator_traits<local_iterator>::is_segmented_iterator is_local_seg_t;
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segment_iterator scur = traits::segment(first);
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local_iterator lcur = traits::local(first);
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while(1) {
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lcur = fill_n_scan(lcur, traits::end(scur), count, value, is_local_seg_t());
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if(count == 0)
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break;
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++scur;
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lcur = traits::begin(scur);
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}
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return traits::compose(scur, lcur);
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}
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template <class OutIt, class Size, class T>
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OutIt segmented_fill_n_ref
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(OutIt first, Size count, const T& value, non_segmented_iterator_tag)
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{
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for(; count > 0; ++first, --count)
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*first = value;
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return first;
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}
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} // namespace detail_algo
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//! Assigns \c value to the first \c count elements starting at \c first.
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//! Returns an iterator past the last filled element.
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//! Exploits segmentation when available.
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@@ -33,7 +163,9 @@ template <class FwdIt, class Size, class T>
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BOOST_CONTAINER_FORCEINLINE
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FwdIt segmented_fill_n(FwdIt first, Size count, const T& value)
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{
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return (segmented_generate_n)(first, count, detail_algo::constref_generator<T>(value));
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typedef segmented_iterator_traits<FwdIt> traits;
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return detail_algo::segmented_fill_n_ref(first, count, value,
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typename traits::is_segmented_iterator());
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}
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} // namespace container
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