Completing the tests revealed that this patch was missing a small change
in include/bits/stl_iterator.h. Here is the updated patch.
libstdc++: [_GLIBCXX_ASSERTIONS] Activate basic debug checks
Use _GLIBCXX_ASSERTIONS as a _GLIBCXX_DEBUG light mode. When
defined it activates
all _GLIBCXX_DEBUG checks but skipping those requiring to loop
through the iterator
range unless in case of constexpr.
libstdc++-v3/ChangeLog:
* include/bits/stl_iterator.h [_GLIBCXX_ASSERTIONS]:
Include <debug/stl_iterator.h>.
* include/debug/debug.h [_GLIBCXX_ASSERTIONS]: Define debug
macros non-empty.
* include/debug/helper_functions.h: Cleanup comment about
removed _Iter_base.
* include/debug/functions.h (__skip_debug_runtime_check):
New, returns false if
_GLIBCXX_DEBUG is defined or if constant evaluated.
(__check_sorted, __check_partitioned_lower,
__check_partitioned_upper): Use latter.
Ok to commit ?
François
On 27/05/21 7:37 pm, François Dumont wrote:
We have been talking for a long time of a debug mode with less impact
on performances.
I propose to simply use the existing _GLIBCXX_ASSERTIONS macro.
libstdc++: [_GLIBCXX_ASSERTIONS] Activate basic debug checks
Use _GLIBCXX_ASSERTIONS as a _GLIBCXX_DEBUG light mode. When
defined it activates
all _GLIBCXX_DEBUG checks but skipping those requiring to loop
through the iterator
range unless in case of constexpr.
libstdc++-v3/ChangeLog:
* include/debug/debug.h [_GLIBCXX_ASSERTIONS]: Define
debug macros non-empty.
* include/debug/helper_functions.h: Cleanup comment about
removed _Iter_base.
* include/debug/functions.h (__skip_debug_runtime_check):
New, returns false if
_GLIBCXX_DEBUG is defined or if constant evaluated.
(__check_sorted, __check_partitioned_lower,
__check_partitioned_upper): Use latter.
Tested under Linux x64.
Ok to commit ?
François
diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h
index 8768624b7d1..015b5da1d18 100644
--- a/libstdc++-v3/include/bits/stl_iterator.h
+++ b/libstdc++-v3/include/bits/stl_iterator.h
@@ -2385,7 +2385,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
-#ifdef _GLIBCXX_DEBUG
+#ifdef _GLIBCXX_ASSERTIONS
# include <debug/stl_iterator.h>
#endif
diff --git a/libstdc++-v3/include/debug/debug.h b/libstdc++-v3/include/debug/debug.h
index 116f2f023e2..2e6ce1c8a93 100644
--- a/libstdc++-v3/include/debug/debug.h
+++ b/libstdc++-v3/include/debug/debug.h
@@ -61,7 +61,7 @@ namespace __gnu_debug
struct _Safe_iterator;
}
-#ifndef _GLIBCXX_DEBUG
+#ifndef _GLIBCXX_ASSERTIONS
# define __glibcxx_requires_cond(_Cond,_Msg)
# define __glibcxx_requires_valid_range(_First,_Last)
diff --git a/libstdc++-v3/include/debug/functions.h b/libstdc++-v3/include/debug/functions.h
index 6cac11f2abd..ee0eb877568 100644
--- a/libstdc++-v3/include/debug/functions.h
+++ b/libstdc++-v3/include/debug/functions.h
@@ -48,6 +48,25 @@ namespace __gnu_debug
template<typename _Sequence>
struct _Is_contiguous_sequence : std::__false_type { };
+ _GLIBCXX20_CONSTEXPR
+ inline bool
+ __skip_debug_runtime_check()
+ {
+ // We could be here while only _GLIBCXX_ASSERTIONS has been defined.
+ // In this case we skip expensive runtime checks, constexpr will still
+ // be checked.
+ return
+#ifndef _GLIBCXX_DEBUG
+# if _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
+ !__builtin_is_constant_evaluated();
+# else
+ true;
+# endif
+#else
+ false;
+#endif
+ }
+
/* Checks that [first, last) is a valid range, and then returns
* __first. This routine is useful when we can't use a separate
* assertion statement because, e.g., we are in a constructor.
@@ -260,8 +279,9 @@ namespace __gnu_debug
inline bool
__check_sorted(const _InputIterator& __first, const _InputIterator& __last)
{
- return __check_sorted_aux(__first, __last,
- std::__iterator_category(__first));
+ return __skip_debug_runtime_check()
+ || __check_sorted_aux(__first, __last,
+ std::__iterator_category(__first));
}
template<typename _InputIterator, typename _Predicate>
@@ -270,8 +290,9 @@ namespace __gnu_debug
__check_sorted(const _InputIterator& __first, const _InputIterator& __last,
_Predicate __pred)
{
- return __check_sorted_aux(__first, __last, __pred,
- std::__iterator_category(__first));
+ return __skip_debug_runtime_check()
+ || __check_sorted_aux(__first, __last, __pred,
+ std::__iterator_category(__first));
}
template<typename _InputIterator>
@@ -351,6 +372,9 @@ namespace __gnu_debug
__check_partitioned_lower(_ForwardIterator __first,
_ForwardIterator __last, const _Tp& __value)
{
+ if (__skip_debug_runtime_check())
+ return true;
+
while (__first != __last && *__first < __value)
++__first;
if (__first != __last)
@@ -368,6 +392,9 @@ namespace __gnu_debug
__check_partitioned_upper(_ForwardIterator __first,
_ForwardIterator __last, const _Tp& __value)
{
+ if (__skip_debug_runtime_check())
+ return true;
+
while (__first != __last && !(__value < *__first))
++__first;
if (__first != __last)
@@ -387,6 +414,9 @@ namespace __gnu_debug
_ForwardIterator __last, const _Tp& __value,
_Pred __pred)
{
+ if (__skip_debug_runtime_check())
+ return true;
+
while (__first != __last && bool(__pred(*__first, __value)))
++__first;
if (__first != __last)
@@ -405,6 +435,9 @@ namespace __gnu_debug
_ForwardIterator __last, const _Tp& __value,
_Pred __pred)
{
+ if (__skip_debug_runtime_check())
+ return true;
+
while (__first != __last && !bool(__pred(__value, *__first)))
++__first;
if (__first != __last)
diff --git a/libstdc++-v3/include/debug/helper_functions.h b/libstdc++-v3/include/debug/helper_functions.h
index c0144ced979..587eba2f3e5 100644
--- a/libstdc++-v3/include/debug/helper_functions.h
+++ b/libstdc++-v3/include/debug/helper_functions.h
@@ -30,8 +30,8 @@
#define _GLIBCXX_DEBUG_HELPER_FUNCTIONS_H 1
#include <bits/move.h> // for __addressof
-#include <bits/stl_iterator_base_types.h> // for iterator_traits,
- // categories and _Iter_base
+#include <bits/stl_iterator_base_types.h> // for iterator_traits and
+ // categories
#include <bits/cpp_type_traits.h> // for __is_integer
#include <bits/stl_pair.h> // for pair
