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Unroll segmented mismatch

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Ion Gaztañaga
2026-03-29 15:28:33 +02:00
parent d7f4f1927a
commit 112ab48698
1 changed files with 60 additions and 9 deletions
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include/boost/container/experimental/segmented_mismatch.hpp
+60 -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/iterators.hpp>
#include <utility>
namespace boost {
@@ -40,12 +41,62 @@ struct mismatch_equal
BOOST_CONTAINER_FORCEINLINE bool operator()(const T& a, const U& b) const { return a == b; }
};
template <class InpIter1, class Sent, class InpIter2, class BinaryPred, class Tag>
#if defined(BOOST_CONTAINER_SEGMENTED_LOOP_UNROLLING)
template <class RAIter1, class RAIter2, class BinaryPred>
std::pair<RAIter1, RAIter2> segmented_mismatch_dispatch
(RAIter1 first1, RAIter1 last1, RAIter2 first2, BinaryPred pred, const non_segmented_iterator_tag &, const std::random_access_iterator_tag &)
{
typedef typename iterator_traits<RAIter1>::difference_type difference_type;
difference_type n = last1 - first1;
while(n >= difference_type(4)) {
if(!pred(*first1, *first2))
goto final_result;
++first1; ++first2;
if(!pred(*first1, *first2))
goto final_result;
++first1; ++first2;
if(!pred(*first1, *first2))
goto final_result;
++first1; ++first2;
if(!pred(*first1, *first2))
goto final_result;
++first1; ++first2;
n -= 4;
}
switch (n % 4) {
case 3:
if(!pred(*first1, *first2))
break;
++first1; ++first2;
BOOST_FALLTHROUGH;
case 2:
if(!pred(*first1, *first2))
break;
++first1; ++first2;
BOOST_FALLTHROUGH;
case 1:
if(!pred(*first1, *first2))
break;
++first1; ++first2;
BOOST_FALLTHROUGH;
default:
break;
}
final_result:
return std::pair<RAIter1, RAIter2>(first1, first2);
}
#endif //BOOST_CONTAINER_SEGMENTED_LOOP_UNROLLING
template <class InpIter1, class Sent, class InpIter2, class BinaryPred, class Tag, class Cat>
typename algo_enable_if_c
< !Tag::value || is_sentinel<Sent, InpIter1>::value
, std::pair<InpIter1, InpIter2>
>::type
segmented_mismatch_dispatch(InpIter1 first1, Sent last1, InpIter2 first2, BinaryPred pred, Tag)
segmented_mismatch_dispatch(InpIter1 first1, Sent last1, InpIter2 first2, BinaryPred pred, Tag, Cat)
{
while (first1 != last1 && pred(*first1, *first2)) {
++first1, ++first2;
@@ -54,9 +105,9 @@ segmented_mismatch_dispatch(InpIter1 first1, Sent last1, InpIter2 first2, Binary
return std::pair<InpIter1, InpIter2>(first1, first2);
}
template <class SegIter, class InpIter2, class BinaryPred>
template <class SegIter, class InpIter2, class BinaryPred, class Cat>
std::pair<SegIter, InpIter2> segmented_mismatch_dispatch
(SegIter first1, SegIter last1, InpIter2 first2, BinaryPred pred, segmented_iterator_tag)
(SegIter first1, SegIter last1, InpIter2 first2, BinaryPred pred, segmented_iterator_tag, Cat)
{
typedef segmented_iterator_traits<SegIter> traits;
typedef typename traits::local_iterator local_iterator;
@@ -70,26 +121,26 @@ std::pair<SegIter, InpIter2> segmented_mismatch_dispatch
segment_iterator const slast = traits::segment(last1);
if(sfirst == slast) {
const local_return_t r = (segmented_mismatch_dispatch)(traits::local(first1), traits::local(last1), first2, pred, is_local_seg_t());
const local_return_t r = (segmented_mismatch_dispatch)(traits::local(first1), traits::local(last1), first2, pred, is_local_seg_t(), Cat());
return return_t(traits::compose(sfirst, r.first), r.second);
}
else {
// First segment
local_iterator le = traits::end(sfirst);
local_return_t r = (segmented_mismatch_dispatch)(traits::local(first1), le, first2, pred, is_local_seg_t());
local_return_t r = (segmented_mismatch_dispatch)(traits::local(first1), le, first2, pred, is_local_seg_t(), Cat());
if (r.first != le)
return return_t(traits::compose(sfirst, r.first), r.second);
// Middle segments
for (++sfirst; sfirst != slast; ++sfirst) {
le = traits::end(sfirst);
r = (segmented_mismatch_dispatch)(traits::begin(sfirst), le, r.second, pred, is_local_seg_t());
r = (segmented_mismatch_dispatch)(traits::begin(sfirst), le, r.second, pred, is_local_seg_t(), Cat());
if (r.first != le)
return return_t(traits::compose(sfirst, r.first), r.second);
}
// Last segment
r = (segmented_mismatch_dispatch)(traits::begin(slast), traits::local(last1), r.second, pred, is_local_seg_t());
r = (segmented_mismatch_dispatch)(traits::begin(slast), traits::local(last1), r.second, pred, is_local_seg_t(), Cat());
return return_t(traits::compose(sfirst, r.first), r.second);
}
}
@@ -105,7 +156,7 @@ segmented_mismatch(InpIter1 first1, Sent last1, InpIter2 first2, BinaryPred pred
{
typedef segmented_iterator_traits<InpIter1> traits;
return detail_algo::segmented_mismatch_dispatch
(first1, last1, first2, pred, typename traits::is_segmented_iterator());
(first1, last1, first2, pred, typename traits::is_segmented_iterator(), typename iterator_traits<InpIter1>::iterator_category());
}
//! Returns a pair of iterators to the first mismatching elements