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.
llvm-svn: 227811
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index a179acf..9c51284 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -4482,12 +4482,6 @@
}
}
-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 @@
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);
