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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);