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Unroll segmented_transform

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Ion Gaztañaga
2026-03-29 19:07:08 +02:00
parent 97b9037ee5
commit 704a6dbe33
1 changed files with 45 additions and 9 deletions
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include/boost/container/experimental/segmented_transform.hpp
+45 -9
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@@ -21,6 +21,7 @@
#include <boost/container/detail/config_begin.hpp>
#include <boost/container/detail/workaround.hpp>
#include <boost/container/experimental/segmented_iterator_traits.hpp>
#include <boost/container/detail/iterator.hpp>
namespace boost {
namespace container {
@@ -30,21 +31,56 @@ OutIter segmented_transform(InIter first, Sent last, OutIter result, UnaryOp op)
namespace detail_algo {
#if defined(BOOST_CONTAINER_SEGMENTED_LOOP_UNROLLING)
template <class InIter, class Sent, class OutIter, class UnaryOp, class Tag>
template <class InIter, class OutIter, class UnaryOp>
OutIter segmented_transform_dispatch
(InIter first, InIter last, OutIter result, UnaryOp op, const non_segmented_iterator_tag &, const std::random_access_iterator_tag &)
{
typedef typename iterator_traits<InIter>::difference_type difference_type;
difference_type n = last - first;
while(n >= difference_type(4)) {
*result = op(*first); ++first; ++result;
*result = op(*first); ++first; ++result;
*result = op(*first); ++first; ++result;
*result = op(*first); ++first; ++result;
n -= 4;
}
switch (n % 4) {
case 3:
*result = op(*first); ++first; ++result;
BOOST_FALLTHROUGH;
case 2:
*result = op(*first); ++first; ++result;
BOOST_FALLTHROUGH;
case 1:
*result = op(*first); ++first; ++result;
BOOST_FALLTHROUGH;
default:
break;
}
return result;
}
#endif //BOOST_CONTAINER_SEGMENTED_LOOP_UNROLLING
template <class InIter, class Sent, class OutIter, class UnaryOp, class Tag, class Cat>
typename algo_enable_if_c<
!Tag::value || is_sentinel<Sent, InIter>::value, OutIter>::type
segmented_transform_dispatch
(InIter first, Sent last, OutIter result, UnaryOp op, Tag)
(InIter first, Sent last, OutIter result, UnaryOp op, Tag, Cat)
{
for(; first != last; ++first, ++result)
*result = op(*first);
return result;
}
template <class SegIter, class OutIter, class UnaryOp>
template <class SegIter, class OutIter, class UnaryOp, class Cat>
OutIter segmented_transform_dispatch
(SegIter first, SegIter last, OutIter result, UnaryOp op, segmented_iterator_tag)
(SegIter first, SegIter last, OutIter result, UnaryOp op, segmented_iterator_tag, Cat)
{
typedef segmented_iterator_traits<SegIter> traits;
typedef typename traits::local_iterator local_iterator;
@@ -56,15 +92,15 @@ OutIter segmented_transform_dispatch
segment_iterator const slast = traits::segment(last);
if(sfirst == slast) {
return (segmented_transform_dispatch)(traits::local(first), traits::local(last), result, op, is_local_seg_t());
return (segmented_transform_dispatch)(traits::local(first), traits::local(last), result, op, is_local_seg_t(), Cat());
}
else {
result = (segmented_transform_dispatch)(traits::local(first), traits::end(sfirst), result, op, is_local_seg_t());
result = (segmented_transform_dispatch)(traits::local(first), traits::end(sfirst), result, op, is_local_seg_t(), Cat());
for(++sfirst; sfirst != slast; ++sfirst)
result = (segmented_transform_dispatch)(traits::begin(sfirst), traits::end(sfirst), result, op, is_local_seg_t());
result = (segmented_transform_dispatch)(traits::begin(sfirst), traits::end(sfirst), result, op, is_local_seg_t(), Cat());
return (segmented_transform_dispatch)(traits::begin(sfirst), traits::local(last), result, op, is_local_seg_t());
return (segmented_transform_dispatch)(traits::begin(sfirst), traits::local(last), result, op, is_local_seg_t(), Cat());
}
}
@@ -79,7 +115,7 @@ OutIter segmented_transform (InIter first, Sent last, OutIter result, UnaryOp op
{
typedef segmented_iterator_traits<InIter> traits;
return detail_algo::segmented_transform_dispatch
(first, last, result, op, typename traits::is_segmented_iterator());
(first, last, result, op, typename traits::is_segmented_iterator(), typename iterator_traits<InIter>::iterator_category());
}
} // namespace container