This refactoring to use RAII doesn't seem to make any difference in
benchmarks, although the generated code for some std::vector operations
seems to be slightly larger. Maybe it will be faster (or slower) in some
cases I didn't test?
I think I like the change anyway - any other opinions on whether it's an
improvement?
Tested x86_64-linux.
-- >8 --
This adds an _UninitDestroyGuard class template, similar to
ranges::_DestroyGuard used in <bits/ranges_uninitialized.h>. This allows
us to remove all the try-catch blocks and rethrows, because any required
cleanup gets done in the guard destructor.
libstdc++-v3/ChangeLog:
* include/bits/stl_uninitialized.h (_UninitDestroyGuard): New
class template and partial specialization.
(__do_uninit_copy, __do_uninit_fill, __do_uninit_fill_n)
(__uninitialized_copy_a, __uninitialized_fill_a)
(__uninitialized_fill_n_a, __uninitialized_copy_move)
(__uninitialized_move_copy, __uninitialized_fill_move)
(__uninitialized_move_fill, __uninitialized_default_1)
(__uninitialized_default_n_a, __uninitialized_default_novalue_1)
(__uninitialized_default_novalue_n_1, __uninitialized_copy_n)
(__uninitialized_copy_n_pair): Use it.
---
libstdc++-v3/include/bits/stl_uninitialized.h | 365 ++++++++----------
1 file changed, 156 insertions(+), 209 deletions(-)
diff --git a/libstdc++-v3/include/bits/stl_uninitialized.h
b/libstdc++-v3/include/bits/stl_uninitialized.h
index 3c405d8fbe8..a9965f26269 100644
--- a/libstdc++-v3/include/bits/stl_uninitialized.h
+++ b/libstdc++-v3/include/bits/stl_uninitialized.h
@@ -107,24 +107,70 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__is_trivial(T) && __is_assignable(T&, U)
#endif
+ template<typename _ForwardIterator, typename _Alloc = void>
+ struct _UninitDestroyGuard
+ {
+ _GLIBCXX20_CONSTEXPR
+ explicit
+ _UninitDestroyGuard(_ForwardIterator& __first, _Alloc& __a)
+ : _M_first(__first), _M_cur(__builtin_addressof(__first)), _M_alloc(__a)
+ { }
+
+ _GLIBCXX20_CONSTEXPR
+ ~_UninitDestroyGuard()
+ {
+ if (__builtin_expect(_M_cur != 0, 0))
+ std::_Destroy(_M_first, *_M_cur, _M_alloc);
+ }
+
+ _GLIBCXX20_CONSTEXPR
+ void release() { _M_cur = 0; }
+
+ private:
+ _ForwardIterator const _M_first;
+ _ForwardIterator* _M_cur;
+ _Alloc& _M_alloc;
+
+ _UninitDestroyGuard(const _UninitDestroyGuard&);
+ };
+
+ template<typename _ForwardIterator>
+ struct _UninitDestroyGuard<_ForwardIterator, void>
+ {
+ _GLIBCXX20_CONSTEXPR
+ explicit
+ _UninitDestroyGuard(_ForwardIterator& __first)
+ : _M_first(__first), _M_cur(__builtin_addressof(__first))
+ { }
+
+ _GLIBCXX20_CONSTEXPR
+ ~_UninitDestroyGuard()
+ {
+ if (__builtin_expect(_M_cur != 0, 0))
+ std::_Destroy(_M_first, *_M_cur);
+ }
+
+ _GLIBCXX20_CONSTEXPR
+ void release() { _M_cur = 0; }
+
+ _ForwardIterator const _M_first;
+ _ForwardIterator* _M_cur;
+
+ private:
+ _UninitDestroyGuard(const _UninitDestroyGuard&);
+ };
+
template<typename _InputIterator, typename _ForwardIterator>
_GLIBCXX20_CONSTEXPR
_ForwardIterator
__do_uninit_copy(_InputIterator __first, _InputIterator __last,
_ForwardIterator __result)
{
- _ForwardIterator __cur = __result;
- __try
- {
- for (; __first != __last; ++__first, (void)++__cur)
- std::_Construct(std::__addressof(*__cur), *__first);
- return __cur;
- }
- __catch(...)
- {
- std::_Destroy(__result, __cur);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator> __guard(__result);
+ for (; __first != __last; ++__first, (void)++__result)
+ std::_Construct(std::__addressof(*__result), *__first);
+ __guard.release();
+ return __result;
}
template<bool _TrivialValueTypes>
@@ -192,17 +238,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__do_uninit_fill(_ForwardIterator __first, _ForwardIterator __last,
const _Tp& __x)
{
- _ForwardIterator __cur = __first;
- __try
- {
- for (; __cur != __last; ++__cur)
- std::_Construct(std::__addressof(*__cur), __x);
- }
- __catch(...)
- {
- std::_Destroy(__first, __cur);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator> __guard(__first);
+ for (; __first != __last; ++__first)
+ std::_Construct(std::__addressof(*__first), __x);
+ __guard.release();
}
template<bool _TrivialValueType>
@@ -260,18 +299,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_ForwardIterator
__do_uninit_fill_n(_ForwardIterator __first, _Size __n, const _Tp& __x)
{
- _ForwardIterator __cur = __first;
- __try
- {
- for (; __n > 0; --__n, (void) ++__cur)
- std::_Construct(std::__addressof(*__cur), __x);
- return __cur;
- }
- __catch(...)
- {
- std::_Destroy(__first, __cur);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator> __guard(__first);
+ for (; __n > 0; --__n, (void) ++__first)
+ std::_Construct(std::__addressof(*__first), __x);
+ __guard.release();
+ return __first;
}
template<bool _TrivialValueType>
@@ -344,19 +376,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__uninitialized_copy_a(_InputIterator __first, _InputIterator __last,
_ForwardIterator __result, _Allocator& __alloc)
{
- _ForwardIterator __cur = __result;
- __try
- {
- typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
- for (; __first != __last; ++__first, (void)++__cur)
- __traits::construct(__alloc, std::__addressof(*__cur), *__first);
- return __cur;
- }
- __catch(...)
- {
- std::_Destroy(__result, __cur, __alloc);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator, _Allocator>
+ __guard(__result, __alloc);
+
+ typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
+ for (; __first != __last; ++__first, (void)++__result)
+ __traits::construct(__alloc, std::__addressof(*__result), *__first);
+ __guard.release();
+ return __result;
}
#if _GLIBCXX_HOSTED
@@ -406,18 +433,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__uninitialized_fill_a(_ForwardIterator __first, _ForwardIterator __last,
const _Tp& __x, _Allocator& __alloc)
{
- _ForwardIterator __cur = __first;
- __try
- {
- typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
- for (; __cur != __last; ++__cur)
- __traits::construct(__alloc, std::__addressof(*__cur), __x);
- }
- __catch(...)
- {
- std::_Destroy(__first, __cur, __alloc);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator, _Allocator>
+ __guard(__first, __alloc);
+
+ typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
+ for (; __first != __last; ++__first)
+ __traits::construct(__alloc, std::__addressof(*__first), __x);
+
+ __guard.release();
}
#if _GLIBCXX_HOSTED
@@ -442,19 +465,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__uninitialized_fill_n_a(_ForwardIterator __first, _Size __n,
const _Tp& __x, _Allocator& __alloc)
{
- _ForwardIterator __cur = __first;
- __try
- {
- typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
- for (; __n > 0; --__n, (void) ++__cur)
- __traits::construct(__alloc, std::__addressof(*__cur), __x);
- return __cur;
- }
- __catch(...)
- {
- std::_Destroy(__first, __cur, __alloc);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator, _Allocator>
+ __guard(__first, __alloc);
+ typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
+ for (; __n > 0; --__n, (void) ++__first)
+ __traits::construct(__alloc, std::__addressof(*__first), __x);
+ __guard.release();
+ return __first;
}
#if _GLIBCXX_HOSTED
@@ -493,17 +510,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Allocator& __alloc)
{
_ForwardIterator __mid = std::__uninitialized_copy_a(__first1, __last1,
- __result,
- __alloc);
- __try
- {
- return std::__uninitialized_move_a(__first2, __last2, __mid, __alloc);
- }
- __catch(...)
- {
- std::_Destroy(__result, __mid, __alloc);
- __throw_exception_again;
- }
+ __result, __alloc);
+ _UninitDestroyGuard<_ForwardIterator, _Allocator> __guard(__result,
+ __alloc);
+ __result = __mid; // Everything up to __mid is now guarded.
+ __result = std::__uninitialized_move_a(__first2, __last2, __mid,
__alloc);
+ __guard.release();
+ return __result;
}
// __uninitialized_move_copy
@@ -521,17 +534,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Allocator& __alloc)
{
_ForwardIterator __mid = std::__uninitialized_move_a(__first1, __last1,
- __result,
- __alloc);
- __try
- {
- return std::__uninitialized_copy_a(__first2, __last2, __mid, __alloc);
- }
- __catch(...)
- {
- std::_Destroy(__result, __mid, __alloc);
- __throw_exception_again;
- }
+ __result, __alloc);
+ _UninitDestroyGuard<_ForwardIterator, _Allocator> __guard(__result,
+ __alloc);
+ __result = __mid; // Everything up to __mid is now guarded.
+ __result = std::__uninitialized_copy_a(__first2, __last2, __mid,
__alloc);
+ __guard.release();
}
// __uninitialized_fill_move
@@ -545,15 +553,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_InputIterator __last, _Allocator& __alloc)
{
std::__uninitialized_fill_a(__result, __mid, __x, __alloc);
- __try
- {
- return std::__uninitialized_move_a(__first, __last, __mid, __alloc);
- }
- __catch(...)
- {
- std::_Destroy(__result, __mid, __alloc);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator, _Allocator> __guard(__result,
+ __alloc);
+ __result = __mid; // Everything up to __mid is now guarded.
+ __result = std::__uninitialized_move_a(__first, __last, __mid, __alloc);
+ __guard.release();
+ return __result;
}
// __uninitialized_move_fill
@@ -570,15 +575,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_ForwardIterator __mid2 = std::__uninitialized_move_a(__first1, __last1,
__first2,
__alloc);
- __try
- {
- std::__uninitialized_fill_a(__mid2, __last2, __x, __alloc);
- }
- __catch(...)
- {
- std::_Destroy(__first2, __mid2, __alloc);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator, _Allocator> __guard(__first2,
+ __alloc);
+ __first2 = __mid2; // Everything up to __mid2 is now guarded.
+ std::__uninitialized_fill_a(__mid2, __last2, __x, __alloc);
+ __guard.release();
}
/// @endcond
@@ -596,17 +597,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static void
__uninit_default(_ForwardIterator __first, _ForwardIterator __last)
{
- _ForwardIterator __cur = __first;
- __try
- {
- for (; __cur != __last; ++__cur)
- std::_Construct(std::__addressof(*__cur));
- }
- __catch(...)
- {
- std::_Destroy(__first, __cur);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator> __guard(__first);
+ for (; __first != __last; ++__first)
+ std::_Construct(std::__addressof(*__first));
+ __guard.release();
}
};
@@ -636,18 +630,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _ForwardIterator
__uninit_default_n(_ForwardIterator __first, _Size __n)
{
- _ForwardIterator __cur = __first;
- __try
- {
- for (; __n > 0; --__n, (void) ++__cur)
- std::_Construct(std::__addressof(*__cur));
- return __cur;
- }
- __catch(...)
- {
- std::_Destroy(__first, __cur);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator> __guard(__first);
+ for (; __n > 0; --__n, (void) ++__first)
+ std::_Construct(std::__addressof(*__first));
+ __guard.release();
+ return __first;
}
};
@@ -722,18 +709,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_ForwardIterator __last,
_Allocator& __alloc)
{
- _ForwardIterator __cur = __first;
- __try
- {
- typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
- for (; __cur != __last; ++__cur)
- __traits::construct(__alloc, std::__addressof(*__cur));
- }
- __catch(...)
- {
- std::_Destroy(__first, __cur, __alloc);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator, _Allocator> __guard(__first,
+ __alloc);
+ typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
+ for (; __first != __last; ++__first)
+ __traits::construct(__alloc, std::__addressof(*__first));
+ __guard.release();
}
#if _GLIBCXX_HOSTED
@@ -753,19 +734,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__uninitialized_default_n_a(_ForwardIterator __first, _Size __n,
_Allocator& __alloc)
{
- _ForwardIterator __cur = __first;
- __try
- {
- typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
- for (; __n > 0; --__n, (void) ++__cur)
- __traits::construct(__alloc, std::__addressof(*__cur));
- return __cur;
- }
- __catch(...)
- {
- std::_Destroy(__first, __cur, __alloc);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator, _Allocator> __guard(__first,
+ __alloc);
+ typedef __gnu_cxx::__alloc_traits<_Allocator> __traits;
+ for (; __n > 0; --__n, (void) ++__first)
+ __traits::construct(__alloc, std::__addressof(*__first));
+ __guard.release();
+ return __first;
}
#if _GLIBCXX_HOSTED
@@ -787,17 +762,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__uninit_default_novalue(_ForwardIterator __first,
_ForwardIterator __last)
{
- _ForwardIterator __cur = __first;
- __try
- {
- for (; __cur != __last; ++__cur)
- std::_Construct_novalue(std::__addressof(*__cur));
- }
- __catch(...)
- {
- std::_Destroy(__first, __cur);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator> __guard(__first);
+ for (; __first != __last; ++__first)
+ std::_Construct_novalue(std::__addressof(*__first));
+ __guard.release();
}
};
@@ -818,18 +786,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static _ForwardIterator
__uninit_default_novalue_n(_ForwardIterator __first, _Size __n)
{
- _ForwardIterator __cur = __first;
- __try
- {
- for (; __n > 0; --__n, (void) ++__cur)
- std::_Construct_novalue(std::__addressof(*__cur));
- return __cur;
- }
- __catch(...)
- {
- std::_Destroy(__first, __cur);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator> __guard(__first);
+ for (; __n > 0; --__n, (void) ++__first)
+ std::_Construct_novalue(std::__addressof(*__first));
+ __guard.release();
+ return __first;
}
};
@@ -877,18 +838,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__uninitialized_copy_n(_InputIterator __first, _Size __n,
_ForwardIterator __result, input_iterator_tag)
{
- _ForwardIterator __cur = __result;
- __try
- {
- for (; __n > 0; --__n, (void) ++__first, ++__cur)
- std::_Construct(std::__addressof(*__cur), *__first);
- return __cur;
- }
- __catch(...)
- {
- std::_Destroy(__result, __cur);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator> __guard(__result);
+ for (; __n > 0; --__n, (void) ++__first, ++__result)
+ std::_Construct(std::__addressof(*__result), *__first);
+ __guard.release();
+ return __result;
}
template<typename _RandomAccessIterator, typename _Size,
@@ -903,20 +857,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
typename _ForwardIterator>
pair<_InputIterator, _ForwardIterator>
__uninitialized_copy_n_pair(_InputIterator __first, _Size __n,
- _ForwardIterator __result, input_iterator_tag)
+ _ForwardIterator __result, input_iterator_tag)
{
- _ForwardIterator __cur = __result;
- __try
- {
- for (; __n > 0; --__n, (void) ++__first, ++__cur)
- std::_Construct(std::__addressof(*__cur), *__first);
- return {__first, __cur};
- }
- __catch(...)
- {
- std::_Destroy(__result, __cur);
- __throw_exception_again;
- }
+ _UninitDestroyGuard<_ForwardIterator> __guard(__result);
+ for (; __n > 0; --__n, (void) ++__first, ++__result)
+ std::_Construct(std::__addressof(*__result), *__first);
+ __guard.release();
+ return {__first, __result};
}
template<typename _RandomAccessIterator, typename _Size,
--
2.45.2
