On 27/04/2015 13:55, Jonathan Wakely wrote:
On 22/04/15 22:10 +0200, François Dumont wrote:
Hello
I don't know if I am missing something but I think __niter_base
could be simplified to remove usage of _Iter_base. Additionally I
overload it to also remove __normal_iterator layer even if behind a
reverse_iterator or move_iterator, might help compiler to optimize
code, no ? If not, might allow other algo optimization in the future...
I prefered to provide a __make_reverse_iterator to allow the
latter in C++11 and not only in C++14. Is it fine to do it this way
or do you prefer to simply get rid of all this part ?
It's fine to add __make_reverse_iterator but see my comment below.
* include/bits/cpp_type_traits.h (__gnu_cxx::__normal_iterator):
Delete.
You're removing __is_normal_iterator not __normal_iterator.
* include/bits/stl_algobase.h (std::__niter_base): Adapt.
* include/bits/stl_iterator.h (__make_reverse_iterator): New in
C++11.
(std::__niter_base): Overloads for std::reverse_iterator,
__gnu_cxx::__normal_iterator and std::move_iterator.
Tested under Linux x86_64. I checked that std::copy still ends up
calling __builtin_memmove when used on vector iterators.
François
diff --git a/libstdc++-v3/include/bits/stl_algobase.h
b/libstdc++-v3/include/bits/stl_algobase.h
index 0bcb133..73eea6b 100644
--- a/libstdc++-v3/include/bits/stl_algobase.h
+++ b/libstdc++-v3/include/bits/stl_algobase.h
@@ -270,17 +270,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return __a;
}
- // If _Iterator is a __normal_iterator return its base (a plain
pointer,
- // normally) otherwise return it untouched. See copy, fill, ...
+ // Fallback implementation of the function used to remove the
+ // __normal_iterator wrapper. See copy, fill, ...
It's a bit strange to have a function with no other overloads visible
described as a fallback. It would be good to say that the other
definition is in bits/stl_iterator.h
template<typename _Iterator>
- struct _Niter_base
- : _Iter_base<_Iterator, __is_normal_iterator<_Iterator>::__value>
- { };
-
- template<typename _Iterator>
- inline typename _Niter_base<_Iterator>::iterator_type
+ inline _Iterator
__niter_base(_Iterator __it)
- { return std::_Niter_base<_Iterator>::_S_base(__it); }
+ { return __it; }
// Likewise, for move_iterator.
This comment no longer makes sense, because you've removed the comment
on _Niter_base that it referred to. Please restore the original text
of the _Niter_base comment for _Miter_base.
(Alternatively, could the same simplification be made for
__miter_base? Do we need _Miter_base<> or just two overloads of
__miter_base()?)
Definitely, I already have a patch for that.
template<typename _Iterator>
diff --git a/libstdc++-v3/include/bits/stl_iterator.h
b/libstdc++-v3/include/bits/stl_iterator.h
index 4a9189e..3aad9f3 100644
--- a/libstdc++-v3/include/bits/stl_iterator.h
+++ b/libstdc++-v3/include/bits/stl_iterator.h
@@ -390,7 +390,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ return __y.base() - __x.base(); }
//@}
-#if __cplusplus > 201103L
+#if __cplusplus == 201103L
+ template<typename _Iterator>
+ inline reverse_iterator<_Iterator>
+ __make_reverse_iterator(_Iterator __i)
+ { return reverse_iterator<_Iterator>(__i); }
+
+# define _GLIBCXX_MAKE_REVERSE_ITERATOR(_Iter) \
+ std::__make_reverse_iterator(_Iter)
+#elif __cplusplus > 201103L
#define __cpp_lib_make_reverse_iterator 201402
// _GLIBCXX_RESOLVE_LIB_DEFECTS
@@ -400,6 +408,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
inline reverse_iterator<_Iterator>
make_reverse_iterator(_Iterator __i)
{ return reverse_iterator<_Iterator>(__i); }
+
+# define _GLIBCXX_MAKE_REVERSE_ITERATOR(_Iter) \
+ std::make_reverse_iterator(_Iter)
+#endif
+
+#if __cplusplus >= 201103L
+ template<typename _Iterator>
+ auto
+ __niter_base(reverse_iterator<_Iterator> __it)
+ ->
decltype(_GLIBCXX_MAKE_REVERSE_ITERATOR(__niter_base(__it.base())))
+ { return
_GLIBCXX_MAKE_REVERSE_ITERATOR(__niter_base(__it.base())); }
#endif
It might be simpler to just add __make_reverse_iterator for >= 201103L
and then always use std::__make_reverse_iterator instead of a macro.
That's similar to what we do for std:__addressof and std:addressof.
Ok, attached is the patch I have plan to commit then that I am testing
at the moment.
François
Index: ChangeLog
===================================================================
--- ChangeLog (revision 222611)
+++ ChangeLog (working copy)
@@ -1,5 +1,14 @@
2015-04-30 François Dumont <fdum...@gcc.gnu.org>
+ * include/bits/cpp_type_traits.h
+ (__gnu_cxx::__is_normal_iterator): Delete.
+ * include/bits/stl_algobase.h (std::__niter_base): Adapt.
+ * include/bits/stl_iterator.h (__make_reverse_iterator): New in C++11.
+ (std::__niter_base): Overloads for std::reverse_iterator,
+ __gnu_cxx::__normal_iterator and std::move_iterator.
+
+2015-04-30 François Dumont <fdum...@gcc.gnu.org>
+
* include/bits/hashtable_policy.h (_Prime_rehash_policy::_S_n_primes):
Delete.
* src/c++11/hashtable_c++0x.cc (_Prime_rehash_policy::_M_next_bkt):
Index: include/bits/cpp_type_traits.h
===================================================================
--- include/bits/cpp_type_traits.h (revision 222610)
+++ include/bits/cpp_type_traits.h (working copy)
@@ -64,17 +64,6 @@
// removed.
//
-// Forward declaration hack, should really include this from somewhere.
-namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
-{
-_GLIBCXX_BEGIN_NAMESPACE_VERSION
-
- template<typename _Iterator, typename _Container>
- class __normal_iterator;
-
-_GLIBCXX_END_NAMESPACE_VERSION
-} // namespace
-
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -331,24 +320,6 @@
};
//
- // Normal iterator type
- //
- template<typename _Tp>
- struct __is_normal_iterator
- {
- enum { __value = 0 };
- typedef __false_type __type;
- };
-
- template<typename _Iterator, typename _Container>
- struct __is_normal_iterator< __gnu_cxx::__normal_iterator<_Iterator,
- _Container> >
- {
- enum { __value = 1 };
- typedef __true_type __type;
- };
-
- //
// An arithmetic type is an integer type or a floating point type
//
template<typename _Tp>
Index: include/bits/stl_algobase.h
===================================================================
--- include/bits/stl_algobase.h (revision 222610)
+++ include/bits/stl_algobase.h (working copy)
@@ -270,19 +270,15 @@
return __a;
}
- // If _Iterator is a __normal_iterator return its base (a plain pointer,
- // normally) otherwise return it untouched. See copy, fill, ...
+ // Fallback implementation of the function in bits/stl_iterator.h used to
+ // remove the __normal_iterator wrapper. See copy, fill, ...
template<typename _Iterator>
- struct _Niter_base
- : _Iter_base<_Iterator, __is_normal_iterator<_Iterator>::__value>
- { };
-
- template<typename _Iterator>
- inline typename _Niter_base<_Iterator>::iterator_type
+ inline _Iterator
__niter_base(_Iterator __it)
- { return std::_Niter_base<_Iterator>::_S_base(__it); }
+ { return __it; }
- // Likewise, for move_iterator.
+ // If _Iterator is a move_iterator return its base otherwise return it
+ // untouched. See copy, fill, ...
template<typename _Iterator>
struct _Miter_base
: _Iter_base<_Iterator, __is_move_iterator<_Iterator>::__value>
Index: include/bits/stl_iterator.h
===================================================================
--- include/bits/stl_iterator.h (revision 222610)
+++ include/bits/stl_iterator.h (working copy)
@@ -388,9 +388,16 @@
{ return __y.base() - __x.base(); }
//@}
-#if __cplusplus > 201103L
-#define __cpp_lib_make_reverse_iterator 201402
+#if __cplusplus >= 201103L
+ // Same as C++14 make_reverse_iterator but used in C++03 mode too.
+ template<typename _Iterator>
+ inline reverse_iterator<_Iterator>
+ __make_reverse_iterator(_Iterator __i)
+ { return reverse_iterator<_Iterator>(__i); }
+# if __cplusplus > 201103L
+# define __cpp_lib_make_reverse_iterator 201402
+
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// DR 2285. make_reverse_iterator
/// Generator function for reverse_iterator.
@@ -398,8 +405,17 @@
inline reverse_iterator<_Iterator>
make_reverse_iterator(_Iterator __i)
{ return reverse_iterator<_Iterator>(__i); }
+# endif
#endif
+#if __cplusplus >= 201103L
+ template<typename _Iterator>
+ auto
+ __niter_base(reverse_iterator<_Iterator> __it)
+ -> decltype(__make_reverse_iterator(__niter_base(__it.base())))
+ { return __make_reverse_iterator(__niter_base(__it.base())); }
+#endif
+
// 24.4.2.2.1 back_insert_iterator
/**
* @brief Turns assignment into insertion.
@@ -935,6 +951,18 @@
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+ template<typename _Iterator, typename _Container>
+ _Iterator
+ __niter_base(__gnu_cxx::__normal_iterator<_Iterator, _Container> __it)
+ { return __it.base(); }
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
+
#if __cplusplus >= 201103L
namespace std _GLIBCXX_VISIBILITY(default)
@@ -1168,6 +1196,12 @@
// @} group iterators
+ template<typename _Iterator>
+ auto
+ __niter_base(move_iterator<_Iterator> __it)
+ -> decltype(make_move_iterator(__niter_base(__it.base())))
+ { return make_move_iterator(__niter_base(__it.base())); }
+
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
