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Fix PR#22427. The implementation of inplace_merge had a \'small data set\' optimization; if either half of the merge was small (i.e, less than 9 items), it did an inplace merge rather than allocating a buffer and doing a faster/smarter merge. However, this failed to satisfy the complexity requirements in the standard. Remove that code. Add tests to check the complexity, and add the same tests for std::merge, since we are in that section of the test suite anyway.

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git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@227811 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Marshall Clow 2015-02-02 17:35:53 +00:00
parent e809f4ce45
commit 4c2684ccf9
3 changed files with 15 additions and 16 deletions
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16
include/algorithm
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@ -4482,12 +4482,6 @@ __inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle,
}
}
template <class _Tp>
struct __inplace_merge_switch
{
static const unsigned value = is_trivially_copy_assignable<_Tp>::value;
};
template <class _BidirectionalIterator, class _Compare>
inline _LIBCPP_INLINE_VISIBILITY
void
@ -4499,13 +4493,9 @@ inplace_merge(_BidirectionalIterator __first, _BidirectionalIterator __middle, _
difference_type __len1 = _VSTD::distance(__first, __middle);
difference_type __len2 = _VSTD::distance(__middle, __last);
difference_type __buf_size = _VSTD::min(__len1, __len2);
pair<value_type*, ptrdiff_t> __buf(0, 0);
unique_ptr<value_type, __return_temporary_buffer> __h;
if (__inplace_merge_switch<value_type>::value && __buf_size > 8)
{
__buf = _VSTD::get_temporary_buffer<value_type>(__buf_size);
__h.reset(__buf.first);
}
pair<value_type*, ptrdiff_t> __buf = _VSTD::get_temporary_buffer<value_type>(__buf_size);
unique_ptr<value_type, __return_temporary_buffer> __h(__buf.first);
#ifdef _LIBCPP_DEBUG
typedef typename add_lvalue_reference<__debug_less<_Compare> >::type _Comp_ref;
__debug_less<_Compare> __c(__comp);

6
test/std/algorithms/alg.sorting/alg.merge/inplace_merge_comp.pass.cpp
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@ -31,6 +31,7 @@ struct indirect_less
#endif // _LIBCPP_HAS_NO_RVALUE_REFERENCES
#include "test_iterators.h"
#include "counting_predicates.hpp"
template <class Iter>
void
@ -43,12 +44,14 @@ test_one(unsigned N, unsigned M)
std::random_shuffle(ia, ia+N);
std::sort(ia, ia+M, std::greater<int>());
std::sort(ia+M, ia+N, std::greater<int>());
std::inplace_merge(Iter(ia), Iter(ia+M), Iter(ia+N), std::greater<int>());
binary_counting_predicate<std::greater<int>, int, int> pred((std::greater<int>()));
std::inplace_merge(Iter(ia), Iter(ia+M), Iter(ia+N), std::ref(pred));
if(N > 0)
{
assert(ia[0] == N-1);
assert(ia[N-1] == 0);
assert(std::is_sorted(ia, ia+N, std::greater<int>()));
assert(pred.count() <= (N-1));
}
delete [] ia;
}
@ -79,6 +82,7 @@ test()
test_one<Iter>(3, 2);
test_one<Iter>(3, 3);
test<Iter>(4);
test<Iter>(20);
test<Iter>(100);
test<Iter>(1000);
}

9
test/std/algorithms/alg.sorting/alg.merge/merge_comp.pass.cpp
View File

@ -25,6 +25,7 @@
#include <cassert>
#include "test_iterators.h"
#include "counting_predicates.hpp"
template <class InIter1, class InIter2, class OutIter>
void
@ -41,12 +42,14 @@ test()
ib[i] = 2*i+1;
std::reverse(ia, ia+N);
std::reverse(ib, ib+N);
binary_counting_predicate<std::greater<int>, int, int> pred((std::greater<int>()));
OutIter r = std::merge(InIter1(ia), InIter1(ia+N),
InIter2(ib), InIter2(ib+N), OutIter(ic), std::greater<int>());
InIter2(ib), InIter2(ib+N), OutIter(ic), pred);
assert(base(r) == ic+2*N);
assert(ic[0] == 2*N-1);
assert(ic[2*N-1] == 0);
assert(std::is_sorted(ic, ic+2*N, std::greater<int>()));
assert(pred.count() <= (N + N - 1));
delete [] ic;
delete [] ib;
delete [] ia;
@ -63,12 +66,14 @@ test()
std::copy(ic+N, ic+2*N, ib);
std::sort(ia, ia+N, std::greater<int>());
std::sort(ib, ib+N, std::greater<int>());
binary_counting_predicate<std::greater<int>, int, int> pred((std::greater<int>()));
OutIter r = std::merge(InIter1(ia), InIter1(ia+N),
InIter2(ib), InIter2(ib+N), OutIter(ic), std::greater<int>());
InIter2(ib), InIter2(ib+N), OutIter(ic), pred);
assert(base(r) == ic+2*N);
assert(ic[0] == 2*N-1);
assert(ic[2*N-1] == 0);
assert(std::is_sorted(ic, ic+2*N, std::greater<int>()));
assert(pred.count() <= (N + N - 1));
delete [] ic;
delete [] ib;
delete [] ia;