* [PATCH] Avoid vector -Wfree-nonheap-object warnings
@ 2024-05-23 4:55 François Dumont
2024-05-23 13:31 ` Jonathan Wakely
0 siblings, 1 reply; 9+ messages in thread
From: François Dumont @ 2024-05-23 4:55 UTC (permalink / raw)
To: libstdc++; +Cc: gcc-patches
[-- Attachment #1: Type: text/plain, Size: 1079 bytes --]
As explained in this email:
https://gcc.gnu.org/pipermail/libstdc++/2024-April/058552.html
I experimented -Wfree-nonheap-object because of my enhancements on algos.
So here is a patch to extend the usage of the _Guard type to other parts
of vector.
libstdc++: Use RAII to replace try/catch blocks
Move _Guard into std::vector declaration and use it to guard all
calls to
vector _M_allocate.
Doing so the compiler has more visibility on what is done with the
pointers
and do not raise anymore the -Wfree-nonheap-object warning.
libstdc++-v3/ChangeLog:
* include/bits/vector.tcc (_Guard): Move...
* include/bits/stl_vector.h: ...here.
(_M_allocate_and_copy): Use latter.
(_M_initialize_dispatch): Likewise and set _M_finish first
from the result
of __uninitialize_fill_n_a that can throw.
(_M_range_initialize): Likewise.
Tested under Linux x86_64, ok to commit ?
François
[-- Attachment #2: vector_patch.txt --]
[-- Type: text/plain, Size: 5932 bytes --]
diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h
index 31169711a48..4ea74e3339a 100644
--- a/libstdc++-v3/include/bits/stl_vector.h
+++ b/libstdc++-v3/include/bits/stl_vector.h
@@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
clear() _GLIBCXX_NOEXCEPT
{ _M_erase_at_end(this->_M_impl._M_start); }
+ private:
+ // RAII guard for allocated storage.
+ struct _Guard
+ {
+ pointer _M_storage; // Storage to deallocate
+ size_type _M_len;
+ _Base& _M_vect;
+
+ _GLIBCXX20_CONSTEXPR
+ _Guard(pointer __s, size_type __l, _Base& __vect)
+ : _M_storage(__s), _M_len(__l), _M_vect(__vect)
+ { }
+
+ _GLIBCXX20_CONSTEXPR
+ ~_Guard()
+ {
+ if (_M_storage)
+ _M_vect._M_deallocate(_M_storage, _M_len);
+ }
+
+ _GLIBCXX20_CONSTEXPR
+ pointer
+ _M_release()
+ {
+ pointer __res = _M_storage;
+ _M_storage = 0;
+ return __res;
+ }
+
+ private:
+ _Guard(const _Guard&);
+ };
+
protected:
/**
* Memory expansion handler. Uses the member allocation function to
@@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
_M_allocate_and_copy(size_type __n,
_ForwardIterator __first, _ForwardIterator __last)
{
- pointer __result = this->_M_allocate(__n);
- __try
- {
- std::__uninitialized_copy_a(__first, __last, __result,
- _M_get_Tp_allocator());
- return __result;
- }
- __catch(...)
- {
- _M_deallocate(__result, __n);
- __throw_exception_again;
- }
+ _Guard __guard(this->_M_allocate(__n), __n, *this);
+ std::__uninitialized_copy_a
+ (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
+ return __guard._M_release();
}
@@ -1642,13 +1667,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
// 438. Ambiguity in the "do the right thing" clause
template<typename _Integer>
void
- _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
+ _M_initialize_dispatch(_Integer __int_n, _Integer __value, __true_type)
{
- this->_M_impl._M_start = _M_allocate(_S_check_init_len(
- static_cast<size_type>(__n), _M_get_Tp_allocator()));
- this->_M_impl._M_end_of_storage =
- this->_M_impl._M_start + static_cast<size_type>(__n);
- _M_fill_initialize(static_cast<size_type>(__n), __value);
+ const size_type __n = static_cast<size_type>(__int_n);
+ _Guard __guard(_M_allocate(_S_check_init_len(
+ __n, _M_get_Tp_allocator())), __n, *this);
+ this->_M_impl._M_finish = std::__uninitialized_fill_n_a
+ (__guard._M_storage, __n, __value, _M_get_Tp_allocator());
+ pointer __start = this->_M_impl._M_start = __guard._M_release();
+ this->_M_impl._M_end_of_storage = __start + __n;
}
// Called by the range constructor to implement [23.1.1]/9
@@ -1690,17 +1717,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
std::forward_iterator_tag)
{
const size_type __n = std::distance(__first, __last);
- this->_M_impl._M_start
- = this->_M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
- this->_M_impl._M_end_of_storage = this->_M_impl._M_start + __n;
- this->_M_impl._M_finish =
- std::__uninitialized_copy_a(__first, __last,
- this->_M_impl._M_start,
- _M_get_Tp_allocator());
+ _Guard __guard(this->_M_allocate(_S_check_init_len(
+ __n, _M_get_Tp_allocator())), __n, *this);
+ this->_M_impl._M_finish = std::__uninitialized_copy_a
+ (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
+ pointer __start = this->_M_impl._M_start = __guard._M_release();
+ this->_M_impl._M_end_of_storage = __start + __n;
}
- // Called by the first initialize_dispatch above and by the
- // vector(n,value,a) constructor.
+ // Called by the vector(n,value,a) constructor.
_GLIBCXX20_CONSTEXPR
void
_M_fill_initialize(size_type __n, const value_type& __value)
diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
index 25df060beee..e31da4f6c4c 100644
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -467,32 +467,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
pointer __new_start(this->_M_allocate(__len));
pointer __new_finish(__new_start);
- // RAII guard for allocated storage.
- struct _Guard
{
- pointer _M_storage; // Storage to deallocate
- size_type _M_len;
- _Tp_alloc_type& _M_alloc;
-
- _GLIBCXX20_CONSTEXPR
- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
- { }
-
- _GLIBCXX20_CONSTEXPR
- ~_Guard()
- {
- if (_M_storage)
- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
- deallocate(_M_alloc, _M_storage, _M_len);
- }
-
- private:
- _Guard(const _Guard&);
- };
-
- {
- _Guard __guard(__new_start, __len, _M_impl);
+ _Guard __guard(__new_start, __len, *this);
// The order of the three operations is dictated by the C++11
// case, where the moves could alter a new element belonging
@@ -596,32 +572,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
pointer __new_start(this->_M_allocate(__len));
pointer __new_finish(__new_start);
- // RAII guard for allocated storage.
- struct _Guard
- {
- pointer _M_storage; // Storage to deallocate
- size_type _M_len;
- _Tp_alloc_type& _M_alloc;
-
- _GLIBCXX20_CONSTEXPR
- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
- { }
-
- _GLIBCXX20_CONSTEXPR
- ~_Guard()
- {
- if (_M_storage)
- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
- deallocate(_M_alloc, _M_storage, _M_len);
- }
-
- private:
- _Guard(const _Guard&);
- };
-
{
- _Guard __guard(__new_start, __len, _M_impl);
+ _Guard __guard(__new_start, __len, *this);
// The order of the three operations is dictated by the C++11
// case, where the moves could alter a new element belonging
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] Avoid vector -Wfree-nonheap-object warnings
2024-05-23 4:55 [PATCH] Avoid vector -Wfree-nonheap-object warnings François Dumont
@ 2024-05-23 13:31 ` Jonathan Wakely
2024-05-23 17:37 ` François Dumont
0 siblings, 1 reply; 9+ messages in thread
From: Jonathan Wakely @ 2024-05-23 13:31 UTC (permalink / raw)
To: François Dumont; +Cc: libstdc++, gcc-patches
On 23/05/24 06:55 +0200, François Dumont wrote:
>As explained in this email:
>
>https://gcc.gnu.org/pipermail/libstdc++/2024-April/058552.html
>
>I experimented -Wfree-nonheap-object because of my enhancements on algos.
>
>So here is a patch to extend the usage of the _Guard type to other
>parts of vector.
Nice, that fixes the warning you were seeing?
We recently got a bug report about -Wfree-nonheap-object in
std::vector, but that is coming from _M_realloc_append which already
uses the RAII guard :-(
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115016
> libstdc++: Use RAII to replace try/catch blocks
>
> Move _Guard into std::vector declaration and use it to guard all
>calls to
> vector _M_allocate.
>
> Doing so the compiler has more visibility on what is done with the
>pointers
> and do not raise anymore the -Wfree-nonheap-object warning.
>
> libstdc++-v3/ChangeLog:
>
> * include/bits/vector.tcc (_Guard): Move...
> * include/bits/stl_vector.h: ...here.
> (_M_allocate_and_copy): Use latter.
> (_M_initialize_dispatch): Likewise and set _M_finish first
>from the result
> of __uninitialize_fill_n_a that can throw.
> (_M_range_initialize): Likewise.
>
>Tested under Linux x86_64, ok to commit ?
>
>François
>
>diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h
>index 31169711a48..4ea74e3339a 100644
>--- a/libstdc++-v3/include/bits/stl_vector.h
>+++ b/libstdc++-v3/include/bits/stl_vector.h
>@@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> clear() _GLIBCXX_NOEXCEPT
> { _M_erase_at_end(this->_M_impl._M_start); }
>
>+ private:
>+ // RAII guard for allocated storage.
>+ struct _Guard
If it's being defined at class scope instead of locally in a member
function, I think a better name would be good. Maybe _Ptr_guard or
_Dealloc_guard or something.
>+ {
>+ pointer _M_storage; // Storage to deallocate
>+ size_type _M_len;
>+ _Base& _M_vect;
>+
>+ _GLIBCXX20_CONSTEXPR
>+ _Guard(pointer __s, size_type __l, _Base& __vect)
>+ : _M_storage(__s), _M_len(__l), _M_vect(__vect)
>+ { }
>+
>+ _GLIBCXX20_CONSTEXPR
>+ ~_Guard()
>+ {
>+ if (_M_storage)
>+ _M_vect._M_deallocate(_M_storage, _M_len);
>+ }
>+
>+ _GLIBCXX20_CONSTEXPR
>+ pointer
>+ _M_release()
>+ {
>+ pointer __res = _M_storage;
>+ _M_storage = 0;
I don't think the NullablePointer requirements include assigning 0,
only from nullptr, which isn't valid in C++98.
https://en.cppreference.com/w/cpp/named_req/NullablePointer
Please use _M_storage = pointer() instead.
>+ return __res;
>+ }
>+
>+ private:
>+ _Guard(const _Guard&);
>+ };
>+
> protected:
> /**
> * Memory expansion handler. Uses the member allocation function to
>@@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> _M_allocate_and_copy(size_type __n,
> _ForwardIterator __first, _ForwardIterator __last)
> {
>- pointer __result = this->_M_allocate(__n);
>- __try
>- {
>- std::__uninitialized_copy_a(__first, __last, __result,
>- _M_get_Tp_allocator());
>- return __result;
>- }
>- __catch(...)
>- {
>- _M_deallocate(__result, __n);
>- __throw_exception_again;
>- }
>+ _Guard __guard(this->_M_allocate(__n), __n, *this);
>+ std::__uninitialized_copy_a
>+ (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
>+ return __guard._M_release();
> }
>
>
>@@ -1642,13 +1667,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> // 438. Ambiguity in the "do the right thing" clause
> template<typename _Integer>
> void
>- _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
>+ _M_initialize_dispatch(_Integer __int_n, _Integer __value, __true_type)
> {
>- this->_M_impl._M_start = _M_allocate(_S_check_init_len(
>- static_cast<size_type>(__n), _M_get_Tp_allocator()));
>- this->_M_impl._M_end_of_storage =
>- this->_M_impl._M_start + static_cast<size_type>(__n);
>- _M_fill_initialize(static_cast<size_type>(__n), __value);
Please fix the comment on _M_fill_initialize if you're removing the
use of it here.
>+ const size_type __n = static_cast<size_type>(__int_n);
>+ _Guard __guard(_M_allocate(_S_check_init_len(
>+ __n, _M_get_Tp_allocator())), __n, *this);
I think this would be easier to read if the _S_check_init_len call was
done first, and maybe the allocation too, since we are going to need a
local __start later anyway. So maybe like this:
template<typename _Integer>
void
_M_initialize_dispatch(_Integer __ni, _Integer __value, __true_type)
{
const size_type __n = static_cast<size_type>(__ni);
pointer __start = _M_allocate(_S_check_init_len(__n),
_M_get_Tp_allocator());
_Guard __guard(__start, __n, *this);
this->_M_impl._M_start = __start;
_M_fill_initialize(__n, __value);
this->_M_impl._M_end_of_storage = __start + __n;
(void) __guard._M_release();
}
Or inline the __uninitialized_fill_n_a call if you want to (but then
fix the comment on _M_fill_initialize). Inlining it does make this
function more consistent with the next one, which calls
__uninitialized_copy_a directly.
>+ this->_M_impl._M_finish = std::__uninitialized_fill_n_a
>+ (__guard._M_storage, __n, __value, _M_get_Tp_allocator());
>+ pointer __start = this->_M_impl._M_start = __guard._M_release();
>+ this->_M_impl._M_end_of_storage = __start + __n;
> }
>
> // Called by the range constructor to implement [23.1.1]/9
>@@ -1690,17 +1717,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> std::forward_iterator_tag)
> {
> const size_type __n = std::distance(__first, __last);
>- this->_M_impl._M_start
>- = this->_M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
>- this->_M_impl._M_end_of_storage = this->_M_impl._M_start + __n;
>- this->_M_impl._M_finish =
>- std::__uninitialized_copy_a(__first, __last,
>- this->_M_impl._M_start,
>- _M_get_Tp_allocator());
>+ _Guard __guard(this->_M_allocate(_S_check_init_len(
>+ __n, _M_get_Tp_allocator())), __n, *this);
Again, I think this would be easier to read if split up into two
statements, rather than doing the _S_check_init_len call and the
_M_allocate call and the _Guard initialization all at once.
>+ this->_M_impl._M_finish = std::__uninitialized_copy_a
>+ (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
>+ pointer __start = this->_M_impl._M_start = __guard._M_release();
>+ this->_M_impl._M_end_of_storage = __start + __n;
> }
>
>- // Called by the first initialize_dispatch above and by the
>- // vector(n,value,a) constructor.
>+ // Called by the vector(n,value,a) constructor.
> _GLIBCXX20_CONSTEXPR
> void
> _M_fill_initialize(size_type __n, const value_type& __value)
>diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
>index 25df060beee..e31da4f6c4c 100644
>--- a/libstdc++-v3/include/bits/vector.tcc
>+++ b/libstdc++-v3/include/bits/vector.tcc
>@@ -467,32 +467,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> pointer __new_start(this->_M_allocate(__len));
> pointer __new_finish(__new_start);
>
>- // RAII guard for allocated storage.
>- struct _Guard
> {
>- pointer _M_storage; // Storage to deallocate
>- size_type _M_len;
>- _Tp_alloc_type& _M_alloc;
>-
>- _GLIBCXX20_CONSTEXPR
>- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
>- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
>- { }
>-
>- _GLIBCXX20_CONSTEXPR
>- ~_Guard()
>- {
>- if (_M_storage)
>- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
>- deallocate(_M_alloc, _M_storage, _M_len);
>- }
>-
>- private:
>- _Guard(const _Guard&);
>- };
>-
>- {
>- _Guard __guard(__new_start, __len, _M_impl);
>+ _Guard __guard(__new_start, __len, *this);
>
> // The order of the three operations is dictated by the C++11
> // case, where the moves could alter a new element belonging
>@@ -596,32 +572,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> pointer __new_start(this->_M_allocate(__len));
> pointer __new_finish(__new_start);
>
>- // RAII guard for allocated storage.
>- struct _Guard
>- {
>- pointer _M_storage; // Storage to deallocate
>- size_type _M_len;
>- _Tp_alloc_type& _M_alloc;
>-
>- _GLIBCXX20_CONSTEXPR
>- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
>- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
>- { }
>-
>- _GLIBCXX20_CONSTEXPR
>- ~_Guard()
>- {
>- if (_M_storage)
>- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
>- deallocate(_M_alloc, _M_storage, _M_len);
>- }
>-
>- private:
>- _Guard(const _Guard&);
>- };
>-
> {
>- _Guard __guard(__new_start, __len, _M_impl);
>+ _Guard __guard(__new_start, __len, *this);
>
> // The order of the three operations is dictated by the C++11
> // case, where the moves could alter a new element belonging
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] Avoid vector -Wfree-nonheap-object warnings
2024-05-23 13:31 ` Jonathan Wakely
@ 2024-05-23 17:37 ` François Dumont
2024-05-24 14:17 ` Jonathan Wakely
0 siblings, 1 reply; 9+ messages in thread
From: François Dumont @ 2024-05-23 17:37 UTC (permalink / raw)
To: Jonathan Wakely; +Cc: libstdc++, gcc-patches
[-- Attachment #1: Type: text/plain, Size: 7183 bytes --]
On 23/05/2024 15:31, Jonathan Wakely wrote:
> On 23/05/24 06:55 +0200, François Dumont wrote:
>> As explained in this email:
>>
>> https://gcc.gnu.org/pipermail/libstdc++/2024-April/058552.html
>>
>> I experimented -Wfree-nonheap-object because of my enhancements on
>> algos.
>>
>> So here is a patch to extend the usage of the _Guard type to other
>> parts of vector.
>
> Nice, that fixes the warning you were seeing?
Yes ! I indeed forgot to say so :-)
>
> We recently got a bug report about -Wfree-nonheap-object in
> std::vector, but that is coming from _M_realloc_append which already
> uses the RAII guard :-(
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115016
Note that I also had to move call to __uninitialized_copy_a before
assigning this->_M_impl._M_start so get rid of the -Wfree-nonheap-object
warn. But _M_realloc_append is already doing potentially throwing
operations before assigning this->_M_impl so it must be something else.
Though it made me notice another occurence of _Guard in this method. Now
replaced too in this new patch.
libstdc++: Use RAII to replace try/catch blocks
Move _Guard into std::vector declaration and use it to guard all
calls to
vector _M_allocate.
Doing so the compiler has more visibility on what is done with the
pointers
and do not raise anymore the -Wfree-nonheap-object warning.
libstdc++-v3/ChangeLog:
* include/bits/vector.tcc (_Guard): Move all the nested
duplicated class...
* include/bits/stl_vector.h (_Guard_alloc): ...here.
(_M_allocate_and_copy): Use latter.
(_M_initialize_dispatch): Likewise and set _M_finish first
from the result
of __uninitialize_fill_n_a that can throw.
(_M_range_initialize): Likewise.
>> diff --git a/libstdc++-v3/include/bits/stl_vector.h
>> b/libstdc++-v3/include/bits/stl_vector.h
>> index 31169711a48..4ea74e3339a 100644
>> --- a/libstdc++-v3/include/bits/stl_vector.h
>> +++ b/libstdc++-v3/include/bits/stl_vector.h
>> @@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>> clear() _GLIBCXX_NOEXCEPT
>> { _M_erase_at_end(this->_M_impl._M_start); }
>>
>> + private:
>> + // RAII guard for allocated storage.
>> + struct _Guard
>
> If it's being defined at class scope instead of locally in a member
> function, I think a better name would be good. Maybe _Ptr_guard or
> _Dealloc_guard or something.
_Guard_alloc chosen.
>
>> + {
>> + pointer _M_storage; // Storage to deallocate
>> + size_type _M_len;
>> + _Base& _M_vect;
>> +
>> + _GLIBCXX20_CONSTEXPR
>> + _Guard(pointer __s, size_type __l, _Base& __vect)
>> + : _M_storage(__s), _M_len(__l), _M_vect(__vect)
>> + { }
>> +
>> + _GLIBCXX20_CONSTEXPR
>> + ~_Guard()
>> + {
>> + if (_M_storage)
>> + _M_vect._M_deallocate(_M_storage, _M_len);
>> + }
>> +
>> + _GLIBCXX20_CONSTEXPR
>> + pointer
>> + _M_release()
>> + {
>> + pointer __res = _M_storage;
>> + _M_storage = 0;
>
> I don't think the NullablePointer requirements include assigning 0,
> only from nullptr, which isn't valid in C++98.
>
> https://en.cppreference.com/w/cpp/named_req/NullablePointer
>
> Please use _M_storage = pointer() instead.
I forgot about user fancy pointer, fixed.
>
>> + return __res;
>> + }
>> +
>> + private:
>> + _Guard(const _Guard&);
>> + };
>> +
>> protected:
>> /**
>> * Memory expansion handler. Uses the member allocation
>> function to
>> @@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>> _M_allocate_and_copy(size_type __n,
>> _ForwardIterator __first, _ForwardIterator __last)
>> {
>> - pointer __result = this->_M_allocate(__n);
>> - __try
>> - {
>> - std::__uninitialized_copy_a(__first, __last, __result,
>> - _M_get_Tp_allocator());
>> - return __result;
>> - }
>> - __catch(...)
>> - {
>> - _M_deallocate(__result, __n);
>> - __throw_exception_again;
>> - }
>> + _Guard __guard(this->_M_allocate(__n), __n, *this);
>> + std::__uninitialized_copy_a
>> + (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
>> + return __guard._M_release();
>> }
>>
>>
>> @@ -1642,13 +1667,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>> // 438. Ambiguity in the "do the right thing" clause
>> template<typename _Integer>
>> void
>> - _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
>> + _M_initialize_dispatch(_Integer __int_n, _Integer __value,
>> __true_type)
>> {
>> - this->_M_impl._M_start = _M_allocate(_S_check_init_len(
>> - static_cast<size_type>(__n), _M_get_Tp_allocator()));
>> - this->_M_impl._M_end_of_storage =
>> - this->_M_impl._M_start + static_cast<size_type>(__n);
>> - _M_fill_initialize(static_cast<size_type>(__n), __value);
>
> Please fix the comment on _M_fill_initialize if you're removing the
> use of it here.
Already done in this initial patch proposal, see below.
>
>> + const size_type __n = static_cast<size_type>(__int_n);
>> + _Guard __guard(_M_allocate(_S_check_init_len(
>> + __n, _M_get_Tp_allocator())), __n, *this);
>
> I think this would be easier to read if the _S_check_init_len call was
> done first, and maybe the allocation too, since we are going to need a
> local __start later anyway. So maybe like this:
>
> template<typename _Integer>
> void
> _M_initialize_dispatch(_Integer __ni, _Integer __value, __true_type)
> {
> const size_type __n = static_cast<size_type>(__ni);
> pointer __start = _M_allocate(_S_check_init_len(__n),
> _M_get_Tp_allocator());
> _Guard __guard(__start, __n, *this);
> this->_M_impl._M_start = __start;
> _M_fill_initialize(__n, __value);
> this->_M_impl._M_end_of_storage = __start + __n;
> (void) __guard._M_release();
> }
>
> Or inline the __uninitialized_fill_n_a call if you want to (but then
> fix the comment on _M_fill_initialize). Inlining it does make this
> function more consistent with the next one, which calls
> __uninitialized_copy_a directly.
Yes, this is why I called __uninitialized_fill_n_a instead and also to
do so *before* assigning _M_impl._M_start.
>> - // Called by the first initialize_dispatch above and by the
>> - // vector(n,value,a) constructor.
>> + // Called by the vector(n,value,a) constructor.
See, it's here :-)
Ok to commit ?
François
[-- Attachment #2: vector_patch.txt --]
[-- Type: text/plain, Size: 6966 bytes --]
diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h
index 31169711a48..30d7201c613 100644
--- a/libstdc++-v3/include/bits/stl_vector.h
+++ b/libstdc++-v3/include/bits/stl_vector.h
@@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
clear() _GLIBCXX_NOEXCEPT
{ _M_erase_at_end(this->_M_impl._M_start); }
+ private:
+ // RAII guard for allocated storage.
+ struct _Guard_alloc
+ {
+ pointer _M_storage; // Storage to deallocate
+ size_type _M_len;
+ _Base& _M_vect;
+
+ _GLIBCXX20_CONSTEXPR
+ _Guard_alloc(pointer __s, size_type __l, _Base& __vect)
+ : _M_storage(__s), _M_len(__l), _M_vect(__vect)
+ { }
+
+ _GLIBCXX20_CONSTEXPR
+ ~_Guard_alloc()
+ {
+ if (_M_storage)
+ _M_vect._M_deallocate(_M_storage, _M_len);
+ }
+
+ _GLIBCXX20_CONSTEXPR
+ pointer
+ _M_release()
+ {
+ pointer __res = _M_storage;
+ _M_storage = pointer();
+ return __res;
+ }
+
+ private:
+ _Guard_alloc(const _Guard_alloc&);
+ };
+
protected:
/**
* Memory expansion handler. Uses the member allocation function to
@@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
_M_allocate_and_copy(size_type __n,
_ForwardIterator __first, _ForwardIterator __last)
{
- pointer __result = this->_M_allocate(__n);
- __try
- {
- std::__uninitialized_copy_a(__first, __last, __result,
- _M_get_Tp_allocator());
- return __result;
- }
- __catch(...)
- {
- _M_deallocate(__result, __n);
- __throw_exception_again;
- }
+ _Guard_alloc __guard(this->_M_allocate(__n), __n, *this);
+ std::__uninitialized_copy_a
+ (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
+ return __guard._M_release();
}
@@ -1642,13 +1667,17 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
// 438. Ambiguity in the "do the right thing" clause
template<typename _Integer>
void
- _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
+ _M_initialize_dispatch(_Integer __int_n, _Integer __value, __true_type)
{
- this->_M_impl._M_start = _M_allocate(_S_check_init_len(
- static_cast<size_type>(__n), _M_get_Tp_allocator()));
- this->_M_impl._M_end_of_storage =
- this->_M_impl._M_start + static_cast<size_type>(__n);
- _M_fill_initialize(static_cast<size_type>(__n), __value);
+ const size_type __n = static_cast<size_type>(__int_n);
+ pointer __start =
+ _M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
+ _Guard_alloc __guard(__start, __n, *this);
+ this->_M_impl._M_finish = std::__uninitialized_fill_n_a
+ (__start, __n, __value, _M_get_Tp_allocator());
+ this->_M_impl._M_start = __start;
+ (void)__guard._M_release();
+ this->_M_impl._M_end_of_storage = __start + __n;
}
// Called by the range constructor to implement [23.1.1]/9
@@ -1690,17 +1719,17 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
std::forward_iterator_tag)
{
const size_type __n = std::distance(__first, __last);
- this->_M_impl._M_start
- = this->_M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
- this->_M_impl._M_end_of_storage = this->_M_impl._M_start + __n;
- this->_M_impl._M_finish =
- std::__uninitialized_copy_a(__first, __last,
- this->_M_impl._M_start,
- _M_get_Tp_allocator());
+ pointer __start =
+ this->_M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
+ _Guard_alloc __guard(__start, __n, *this);
+ this->_M_impl._M_finish = std::__uninitialized_copy_a
+ (__first, __last, __start, _M_get_Tp_allocator());
+ this->_M_impl._M_start = __start;
+ (void) __guard._M_release();
+ this->_M_impl._M_end_of_storage = __start + __n;
}
- // Called by the first initialize_dispatch above and by the
- // vector(n,value,a) constructor.
+ // Called by the vector(n,value,a) constructor.
_GLIBCXX20_CONSTEXPR
void
_M_fill_initialize(size_type __n, const value_type& __value)
diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
index 25df060beee..36b27dce7b9 100644
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -467,32 +467,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
pointer __new_start(this->_M_allocate(__len));
pointer __new_finish(__new_start);
- // RAII guard for allocated storage.
- struct _Guard
{
- pointer _M_storage; // Storage to deallocate
- size_type _M_len;
- _Tp_alloc_type& _M_alloc;
-
- _GLIBCXX20_CONSTEXPR
- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
- { }
-
- _GLIBCXX20_CONSTEXPR
- ~_Guard()
- {
- if (_M_storage)
- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
- deallocate(_M_alloc, _M_storage, _M_len);
- }
-
- private:
- _Guard(const _Guard&);
- };
-
- {
- _Guard __guard(__new_start, __len, _M_impl);
+ _Guard_alloc __guard(__new_start, __len, *this);
// The order of the three operations is dictated by the C++11
// case, where the moves could alter a new element belonging
@@ -596,32 +572,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
pointer __new_start(this->_M_allocate(__len));
pointer __new_finish(__new_start);
- // RAII guard for allocated storage.
- struct _Guard
{
- pointer _M_storage; // Storage to deallocate
- size_type _M_len;
- _Tp_alloc_type& _M_alloc;
-
- _GLIBCXX20_CONSTEXPR
- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
- { }
-
- _GLIBCXX20_CONSTEXPR
- ~_Guard()
- {
- if (_M_storage)
- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
- deallocate(_M_alloc, _M_storage, _M_len);
- }
-
- private:
- _Guard(const _Guard&);
- };
-
- {
- _Guard __guard(__new_start, __len, _M_impl);
+ _Guard_alloc __guard(__new_start, __len, *this);
// The order of the three operations is dictated by the C++11
// case, where the moves could alter a new element belonging
@@ -833,32 +785,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
_M_check_len(__n, "vector::_M_default_append");
pointer __new_start(this->_M_allocate(__len));
- // RAII guard for allocated storage.
- struct _Guard
- {
- pointer _M_storage; // Storage to deallocate
- size_type _M_len;
- _Tp_alloc_type& _M_alloc;
-
- _GLIBCXX20_CONSTEXPR
- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
- { }
-
- _GLIBCXX20_CONSTEXPR
- ~_Guard()
- {
- if (_M_storage)
- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
- deallocate(_M_alloc, _M_storage, _M_len);
- }
-
- private:
- _Guard(const _Guard&);
- };
-
{
- _Guard __guard(__new_start, __len, _M_impl);
+ _Guard_alloc __guard(__new_start, __len, *this);
std::__uninitialized_default_n_a(__new_start + __size, __n,
_M_get_Tp_allocator());
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] Avoid vector -Wfree-nonheap-object warnings
2024-05-23 17:37 ` François Dumont
@ 2024-05-24 14:17 ` Jonathan Wakely
2024-05-25 9:59 ` François Dumont
2024-05-27 4:37 ` François Dumont
0 siblings, 2 replies; 9+ messages in thread
From: Jonathan Wakely @ 2024-05-24 14:17 UTC (permalink / raw)
To: François Dumont; +Cc: libstdc++, gcc-patches
On Thu, 23 May 2024 at 18:38, François Dumont <frs.dumont@gmail.com> wrote:
>
>
> On 23/05/2024 15:31, Jonathan Wakely wrote:
> > On 23/05/24 06:55 +0200, François Dumont wrote:
> >> As explained in this email:
> >>
> >> https://gcc.gnu.org/pipermail/libstdc++/2024-April/058552.html
> >>
> >> I experimented -Wfree-nonheap-object because of my enhancements on
> >> algos.
> >>
> >> So here is a patch to extend the usage of the _Guard type to other
> >> parts of vector.
> >
> > Nice, that fixes the warning you were seeing?
>
> Yes ! I indeed forgot to say so :-)
>
>
> >
> > We recently got a bug report about -Wfree-nonheap-object in
> > std::vector, but that is coming from _M_realloc_append which already
> > uses the RAII guard :-(
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115016
>
> Note that I also had to move call to __uninitialized_copy_a before
> assigning this->_M_impl._M_start so get rid of the -Wfree-nonheap-object
> warn. But _M_realloc_append is already doing potentially throwing
> operations before assigning this->_M_impl so it must be something else.
>
> Though it made me notice another occurence of _Guard in this method. Now
> replaced too in this new patch.
>
> libstdc++: Use RAII to replace try/catch blocks
>
> Move _Guard into std::vector declaration and use it to guard all
> calls to
> vector _M_allocate.
>
> Doing so the compiler has more visibility on what is done with the
> pointers
> and do not raise anymore the -Wfree-nonheap-object warning.
>
> libstdc++-v3/ChangeLog:
>
> * include/bits/vector.tcc (_Guard): Move all the nested
> duplicated class...
> * include/bits/stl_vector.h (_Guard_alloc): ...here.
> (_M_allocate_and_copy): Use latter.
> (_M_initialize_dispatch): Likewise and set _M_finish first
> from the result
> of __uninitialize_fill_n_a that can throw.
> (_M_range_initialize): Likewise.
>
> >> diff --git a/libstdc++-v3/include/bits/stl_vector.h
> >> b/libstdc++-v3/include/bits/stl_vector.h
> >> index 31169711a48..4ea74e3339a 100644
> >> --- a/libstdc++-v3/include/bits/stl_vector.h
> >> +++ b/libstdc++-v3/include/bits/stl_vector.h
> >> @@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> >> clear() _GLIBCXX_NOEXCEPT
> >> { _M_erase_at_end(this->_M_impl._M_start); }
> >>
> >> + private:
> >> + // RAII guard for allocated storage.
> >> + struct _Guard
> >
> > If it's being defined at class scope instead of locally in a member
> > function, I think a better name would be good. Maybe _Ptr_guard or
> > _Dealloc_guard or something.
> _Guard_alloc chosen.
> >
> >> + {
> >> + pointer _M_storage; // Storage to deallocate
> >> + size_type _M_len;
> >> + _Base& _M_vect;
> >> +
> >> + _GLIBCXX20_CONSTEXPR
> >> + _Guard(pointer __s, size_type __l, _Base& __vect)
> >> + : _M_storage(__s), _M_len(__l), _M_vect(__vect)
> >> + { }
> >> +
> >> + _GLIBCXX20_CONSTEXPR
> >> + ~_Guard()
> >> + {
> >> + if (_M_storage)
> >> + _M_vect._M_deallocate(_M_storage, _M_len);
> >> + }
> >> +
> >> + _GLIBCXX20_CONSTEXPR
> >> + pointer
> >> + _M_release()
> >> + {
> >> + pointer __res = _M_storage;
> >> + _M_storage = 0;
> >
> > I don't think the NullablePointer requirements include assigning 0,
> > only from nullptr, which isn't valid in C++98.
> >
> > https://en.cppreference.com/w/cpp/named_req/NullablePointer
> >
> > Please use _M_storage = pointer() instead.
>
> I forgot about user fancy pointer, fixed.
>
>
> >
> >> + return __res;
> >> + }
> >> +
> >> + private:
> >> + _Guard(const _Guard&);
> >> + };
> >> +
> >> protected:
> >> /**
> >> * Memory expansion handler. Uses the member allocation
> >> function to
> >> @@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> >> _M_allocate_and_copy(size_type __n,
> >> _ForwardIterator __first, _ForwardIterator __last)
> >> {
> >> - pointer __result = this->_M_allocate(__n);
> >> - __try
> >> - {
> >> - std::__uninitialized_copy_a(__first, __last, __result,
> >> - _M_get_Tp_allocator());
> >> - return __result;
> >> - }
> >> - __catch(...)
> >> - {
> >> - _M_deallocate(__result, __n);
> >> - __throw_exception_again;
> >> - }
> >> + _Guard __guard(this->_M_allocate(__n), __n, *this);
> >> + std::__uninitialized_copy_a
> >> + (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
> >> + return __guard._M_release();
> >> }
> >>
> >>
> >> @@ -1642,13 +1667,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> >> // 438. Ambiguity in the "do the right thing" clause
> >> template<typename _Integer>
> >> void
> >> - _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
> >> + _M_initialize_dispatch(_Integer __int_n, _Integer __value,
> >> __true_type)
> >> {
> >> - this->_M_impl._M_start = _M_allocate(_S_check_init_len(
> >> - static_cast<size_type>(__n), _M_get_Tp_allocator()));
> >> - this->_M_impl._M_end_of_storage =
> >> - this->_M_impl._M_start + static_cast<size_type>(__n);
> >> - _M_fill_initialize(static_cast<size_type>(__n), __value);
> >
> > Please fix the comment on _M_fill_initialize if you're removing the
> > use of it here.
>
> Already done in this initial patch proposal, see below.
>
> >
> >> + const size_type __n = static_cast<size_type>(__int_n);
> >> + _Guard __guard(_M_allocate(_S_check_init_len(
> >> + __n, _M_get_Tp_allocator())), __n, *this);
> >
> > I think this would be easier to read if the _S_check_init_len call was
> > done first, and maybe the allocation too, since we are going to need a
> > local __start later anyway. So maybe like this:
> >
> > template<typename _Integer>
> > void
> > _M_initialize_dispatch(_Integer __ni, _Integer __value, __true_type)
> > {
> > const size_type __n = static_cast<size_type>(__ni);
> > pointer __start = _M_allocate(_S_check_init_len(__n),
> > _M_get_Tp_allocator());
> > _Guard __guard(__start, __n, *this);
> > this->_M_impl._M_start = __start;
> > _M_fill_initialize(__n, __value);
> > this->_M_impl._M_end_of_storage = __start + __n;
> > (void) __guard._M_release();
> > }
> >
> > Or inline the __uninitialized_fill_n_a call if you want to (but then
> > fix the comment on _M_fill_initialize). Inlining it does make this
> > function more consistent with the next one, which calls
> > __uninitialized_copy_a directly.
>
> Yes, this is why I called __uninitialized_fill_n_a instead and also to
> do so *before* assigning _M_impl._M_start.
>
>
> >> - // Called by the first initialize_dispatch above and by the
> >> - // vector(n,value,a) constructor.
> >> + // Called by the vector(n,value,a) constructor.
>
> See, it's here :-)
Doh! Sorry, I'm not sure how I missed that.
>
> Ok to commit ?
OK for trunk, thanks!
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] Avoid vector -Wfree-nonheap-object warnings
2024-05-24 14:17 ` Jonathan Wakely
@ 2024-05-25 9:59 ` François Dumont
2024-05-27 4:37 ` François Dumont
1 sibling, 0 replies; 9+ messages in thread
From: François Dumont @ 2024-05-25 9:59 UTC (permalink / raw)
To: Jonathan Wakely; +Cc: libstdc++, gcc-patches
On 24/05/2024 16:17, Jonathan Wakely wrote:
> On Thu, 23 May 2024 at 18:38, François Dumont <frs.dumont@gmail.com> wrote:
>>
>> On 23/05/2024 15:31, Jonathan Wakely wrote:
>>> On 23/05/24 06:55 +0200, François Dumont wrote:
>>>> As explained in this email:
>>>>
>>>> https://gcc.gnu.org/pipermail/libstdc++/2024-April/058552.html
>>>>
>>>> I experimented -Wfree-nonheap-object because of my enhancements on
>>>> algos.
>>>>
>>>> So here is a patch to extend the usage of the _Guard type to other
>>>> parts of vector.
>>> Nice, that fixes the warning you were seeing?
>> Yes ! I indeed forgot to say so :-)
>>
>>
>>> We recently got a bug report about -Wfree-nonheap-object in
>>> std::vector, but that is coming from _M_realloc_append which already
>>> uses the RAII guard :-(
>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115016
>> Note that I also had to move call to __uninitialized_copy_a before
>> assigning this->_M_impl._M_start so get rid of the -Wfree-nonheap-object
>> warn. But _M_realloc_append is already doing potentially throwing
>> operations before assigning this->_M_impl so it must be something else.
>>
>> Though it made me notice another occurence of _Guard in this method. Now
>> replaced too in this new patch.
>>
>> libstdc++: Use RAII to replace try/catch blocks
>>
>> Move _Guard into std::vector declaration and use it to guard all
>> calls to
>> vector _M_allocate.
>>
>> Doing so the compiler has more visibility on what is done with the
>> pointers
>> and do not raise anymore the -Wfree-nonheap-object warning.
>>
>> libstdc++-v3/ChangeLog:
>>
>> * include/bits/vector.tcc (_Guard): Move all the nested
>> duplicated class...
>> * include/bits/stl_vector.h (_Guard_alloc): ...here.
>> (_M_allocate_and_copy): Use latter.
>> (_M_initialize_dispatch): Likewise and set _M_finish first
>> from the result
>> of __uninitialize_fill_n_a that can throw.
>> (_M_range_initialize): Likewise.
>>
>>>> diff --git a/libstdc++-v3/include/bits/stl_vector.h
>>>> b/libstdc++-v3/include/bits/stl_vector.h
>>>> index 31169711a48..4ea74e3339a 100644
>>>> --- a/libstdc++-v3/include/bits/stl_vector.h
>>>> +++ b/libstdc++-v3/include/bits/stl_vector.h
>>>> @@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>>>> clear() _GLIBCXX_NOEXCEPT
>>>> { _M_erase_at_end(this->_M_impl._M_start); }
>>>>
>>>> + private:
>>>> + // RAII guard for allocated storage.
>>>> + struct _Guard
>>> If it's being defined at class scope instead of locally in a member
>>> function, I think a better name would be good. Maybe _Ptr_guard or
>>> _Dealloc_guard or something.
>> _Guard_alloc chosen.
>>>> + {
>>>> + pointer _M_storage; // Storage to deallocate
>>>> + size_type _M_len;
>>>> + _Base& _M_vect;
>>>> +
>>>> + _GLIBCXX20_CONSTEXPR
>>>> + _Guard(pointer __s, size_type __l, _Base& __vect)
>>>> + : _M_storage(__s), _M_len(__l), _M_vect(__vect)
>>>> + { }
>>>> +
>>>> + _GLIBCXX20_CONSTEXPR
>>>> + ~_Guard()
>>>> + {
>>>> + if (_M_storage)
>>>> + _M_vect._M_deallocate(_M_storage, _M_len);
>>>> + }
>>>> +
>>>> + _GLIBCXX20_CONSTEXPR
>>>> + pointer
>>>> + _M_release()
>>>> + {
>>>> + pointer __res = _M_storage;
>>>> + _M_storage = 0;
>>> I don't think the NullablePointer requirements include assigning 0,
>>> only from nullptr, which isn't valid in C++98.
>>>
>>> https://en.cppreference.com/w/cpp/named_req/NullablePointer
>>>
>>> Please use _M_storage = pointer() instead.
>> I forgot about user fancy pointer, fixed.
>>
>>
>>>> + return __res;
>>>> + }
>>>> +
>>>> + private:
>>>> + _Guard(const _Guard&);
>>>> + };
>>>> +
>>>> protected:
>>>> /**
>>>> * Memory expansion handler. Uses the member allocation
>>>> function to
>>>> @@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>>>> _M_allocate_and_copy(size_type __n,
>>>> _ForwardIterator __first, _ForwardIterator __last)
>>>> {
>>>> - pointer __result = this->_M_allocate(__n);
>>>> - __try
>>>> - {
>>>> - std::__uninitialized_copy_a(__first, __last, __result,
>>>> - _M_get_Tp_allocator());
>>>> - return __result;
>>>> - }
>>>> - __catch(...)
>>>> - {
>>>> - _M_deallocate(__result, __n);
>>>> - __throw_exception_again;
>>>> - }
>>>> + _Guard __guard(this->_M_allocate(__n), __n, *this);
>>>> + std::__uninitialized_copy_a
>>>> + (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
>>>> + return __guard._M_release();
>>>> }
>>>>
>>>>
>>>> @@ -1642,13 +1667,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>>>> // 438. Ambiguity in the "do the right thing" clause
>>>> template<typename _Integer>
>>>> void
>>>> - _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
>>>> + _M_initialize_dispatch(_Integer __int_n, _Integer __value,
>>>> __true_type)
>>>> {
>>>> - this->_M_impl._M_start = _M_allocate(_S_check_init_len(
>>>> - static_cast<size_type>(__n), _M_get_Tp_allocator()));
>>>> - this->_M_impl._M_end_of_storage =
>>>> - this->_M_impl._M_start + static_cast<size_type>(__n);
>>>> - _M_fill_initialize(static_cast<size_type>(__n), __value);
>>> Please fix the comment on _M_fill_initialize if you're removing the
>>> use of it here.
>> Already done in this initial patch proposal, see below.
>>
>>>> + const size_type __n = static_cast<size_type>(__int_n);
>>>> + _Guard __guard(_M_allocate(_S_check_init_len(
>>>> + __n, _M_get_Tp_allocator())), __n, *this);
>>> I think this would be easier to read if the _S_check_init_len call was
>>> done first, and maybe the allocation too, since we are going to need a
>>> local __start later anyway. So maybe like this:
>>>
>>> template<typename _Integer>
>>> void
>>> _M_initialize_dispatch(_Integer __ni, _Integer __value, __true_type)
>>> {
>>> const size_type __n = static_cast<size_type>(__ni);
>>> pointer __start = _M_allocate(_S_check_init_len(__n),
>>> _M_get_Tp_allocator());
>>> _Guard __guard(__start, __n, *this);
>>> this->_M_impl._M_start = __start;
>>> _M_fill_initialize(__n, __value);
>>> this->_M_impl._M_end_of_storage = __start + __n;
>>> (void) __guard._M_release();
>>> }
>>>
>>> Or inline the __uninitialized_fill_n_a call if you want to (but then
>>> fix the comment on _M_fill_initialize). Inlining it does make this
>>> function more consistent with the next one, which calls
>>> __uninitialized_copy_a directly.
>> Yes, this is why I called __uninitialized_fill_n_a instead and also to
>> do so *before* assigning _M_impl._M_start.
>> Ok to commit ?
> OK for trunk, thanks!
>
There are test failures in C++98, working on it.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] Avoid vector -Wfree-nonheap-object warnings
2024-05-24 14:17 ` Jonathan Wakely
2024-05-25 9:59 ` François Dumont
@ 2024-05-27 4:37 ` François Dumont
2024-05-28 10:30 ` Jonathan Wakely
1 sibling, 1 reply; 9+ messages in thread
From: François Dumont @ 2024-05-27 4:37 UTC (permalink / raw)
To: Jonathan Wakely; +Cc: libstdc++, gcc-patches
[-- Attachment #1: Type: text/plain, Size: 7505 bytes --]
Here is a new version working also in C++98.
Note that I have this failure:
FAIL: 23_containers/vector/types/1.cc -std=gnu++98 (test for excess errors)
but it's already failing on master, my patch do not change anything.
Tested under Linux x64,
still ok to commit ?
François
On 24/05/2024 16:17, Jonathan Wakely wrote:
> On Thu, 23 May 2024 at 18:38, François Dumont <frs.dumont@gmail.com> wrote:
>>
>> On 23/05/2024 15:31, Jonathan Wakely wrote:
>>> On 23/05/24 06:55 +0200, François Dumont wrote:
>>>> As explained in this email:
>>>>
>>>> https://gcc.gnu.org/pipermail/libstdc++/2024-April/058552.html
>>>>
>>>> I experimented -Wfree-nonheap-object because of my enhancements on
>>>> algos.
>>>>
>>>> So here is a patch to extend the usage of the _Guard type to other
>>>> parts of vector.
>>> Nice, that fixes the warning you were seeing?
>> Yes ! I indeed forgot to say so :-)
>>
>>
>>> We recently got a bug report about -Wfree-nonheap-object in
>>> std::vector, but that is coming from _M_realloc_append which already
>>> uses the RAII guard :-(
>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115016
>> Note that I also had to move call to __uninitialized_copy_a before
>> assigning this->_M_impl._M_start so get rid of the -Wfree-nonheap-object
>> warn. But _M_realloc_append is already doing potentially throwing
>> operations before assigning this->_M_impl so it must be something else.
>>
>> Though it made me notice another occurence of _Guard in this method. Now
>> replaced too in this new patch.
>>
>> libstdc++: Use RAII to replace try/catch blocks
>>
>> Move _Guard into std::vector declaration and use it to guard all
>> calls to
>> vector _M_allocate.
>>
>> Doing so the compiler has more visibility on what is done with the
>> pointers
>> and do not raise anymore the -Wfree-nonheap-object warning.
>>
>> libstdc++-v3/ChangeLog:
>>
>> * include/bits/vector.tcc (_Guard): Move all the nested
>> duplicated class...
>> * include/bits/stl_vector.h (_Guard_alloc): ...here.
>> (_M_allocate_and_copy): Use latter.
>> (_M_initialize_dispatch): Likewise and set _M_finish first
>> from the result
>> of __uninitialize_fill_n_a that can throw.
>> (_M_range_initialize): Likewise.
>>
>>>> diff --git a/libstdc++-v3/include/bits/stl_vector.h
>>>> b/libstdc++-v3/include/bits/stl_vector.h
>>>> index 31169711a48..4ea74e3339a 100644
>>>> --- a/libstdc++-v3/include/bits/stl_vector.h
>>>> +++ b/libstdc++-v3/include/bits/stl_vector.h
>>>> @@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>>>> clear() _GLIBCXX_NOEXCEPT
>>>> { _M_erase_at_end(this->_M_impl._M_start); }
>>>>
>>>> + private:
>>>> + // RAII guard for allocated storage.
>>>> + struct _Guard
>>> If it's being defined at class scope instead of locally in a member
>>> function, I think a better name would be good. Maybe _Ptr_guard or
>>> _Dealloc_guard or something.
>> _Guard_alloc chosen.
>>>> + {
>>>> + pointer _M_storage; // Storage to deallocate
>>>> + size_type _M_len;
>>>> + _Base& _M_vect;
>>>> +
>>>> + _GLIBCXX20_CONSTEXPR
>>>> + _Guard(pointer __s, size_type __l, _Base& __vect)
>>>> + : _M_storage(__s), _M_len(__l), _M_vect(__vect)
>>>> + { }
>>>> +
>>>> + _GLIBCXX20_CONSTEXPR
>>>> + ~_Guard()
>>>> + {
>>>> + if (_M_storage)
>>>> + _M_vect._M_deallocate(_M_storage, _M_len);
>>>> + }
>>>> +
>>>> + _GLIBCXX20_CONSTEXPR
>>>> + pointer
>>>> + _M_release()
>>>> + {
>>>> + pointer __res = _M_storage;
>>>> + _M_storage = 0;
>>> I don't think the NullablePointer requirements include assigning 0,
>>> only from nullptr, which isn't valid in C++98.
>>>
>>> https://en.cppreference.com/w/cpp/named_req/NullablePointer
>>>
>>> Please use _M_storage = pointer() instead.
>> I forgot about user fancy pointer, fixed.
>>
>>
>>>> + return __res;
>>>> + }
>>>> +
>>>> + private:
>>>> + _Guard(const _Guard&);
>>>> + };
>>>> +
>>>> protected:
>>>> /**
>>>> * Memory expansion handler. Uses the member allocation
>>>> function to
>>>> @@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>>>> _M_allocate_and_copy(size_type __n,
>>>> _ForwardIterator __first, _ForwardIterator __last)
>>>> {
>>>> - pointer __result = this->_M_allocate(__n);
>>>> - __try
>>>> - {
>>>> - std::__uninitialized_copy_a(__first, __last, __result,
>>>> - _M_get_Tp_allocator());
>>>> - return __result;
>>>> - }
>>>> - __catch(...)
>>>> - {
>>>> - _M_deallocate(__result, __n);
>>>> - __throw_exception_again;
>>>> - }
>>>> + _Guard __guard(this->_M_allocate(__n), __n, *this);
>>>> + std::__uninitialized_copy_a
>>>> + (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
>>>> + return __guard._M_release();
>>>> }
>>>>
>>>>
>>>> @@ -1642,13 +1667,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>>>> // 438. Ambiguity in the "do the right thing" clause
>>>> template<typename _Integer>
>>>> void
>>>> - _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
>>>> + _M_initialize_dispatch(_Integer __int_n, _Integer __value,
>>>> __true_type)
>>>> {
>>>> - this->_M_impl._M_start = _M_allocate(_S_check_init_len(
>>>> - static_cast<size_type>(__n), _M_get_Tp_allocator()));
>>>> - this->_M_impl._M_end_of_storage =
>>>> - this->_M_impl._M_start + static_cast<size_type>(__n);
>>>> - _M_fill_initialize(static_cast<size_type>(__n), __value);
>>> Please fix the comment on _M_fill_initialize if you're removing the
>>> use of it here.
>> Already done in this initial patch proposal, see below.
>>
>>>> + const size_type __n = static_cast<size_type>(__int_n);
>>>> + _Guard __guard(_M_allocate(_S_check_init_len(
>>>> + __n, _M_get_Tp_allocator())), __n, *this);
>>> I think this would be easier to read if the _S_check_init_len call was
>>> done first, and maybe the allocation too, since we are going to need a
>>> local __start later anyway. So maybe like this:
>>>
>>> template<typename _Integer>
>>> void
>>> _M_initialize_dispatch(_Integer __ni, _Integer __value, __true_type)
>>> {
>>> const size_type __n = static_cast<size_type>(__ni);
>>> pointer __start = _M_allocate(_S_check_init_len(__n),
>>> _M_get_Tp_allocator());
>>> _Guard __guard(__start, __n, *this);
>>> this->_M_impl._M_start = __start;
>>> _M_fill_initialize(__n, __value);
>>> this->_M_impl._M_end_of_storage = __start + __n;
>>> (void) __guard._M_release();
>>> }
>>>
>>> Or inline the __uninitialized_fill_n_a call if you want to (but then
>>> fix the comment on _M_fill_initialize). Inlining it does make this
>>> function more consistent with the next one, which calls
>>> __uninitialized_copy_a directly.
>> Yes, this is why I called __uninitialized_fill_n_a instead and also to
>> do so *before* assigning _M_impl._M_start.
>>
>>
>>>> - // Called by the first initialize_dispatch above and by the
>>>> - // vector(n,value,a) constructor.
>>>> + // Called by the vector(n,value,a) constructor.
>> See, it's here :-)
> Doh! Sorry, I'm not sure how I missed that.
>
>> Ok to commit ?
> OK for trunk, thanks!
>
[-- Attachment #2: vector_patch.txt --]
[-- Type: text/plain, Size: 8321 bytes --]
diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h
index 31169711a48..81fe3825064 100644
--- a/libstdc++-v3/include/bits/stl_vector.h
+++ b/libstdc++-v3/include/bits/stl_vector.h
@@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
clear() _GLIBCXX_NOEXCEPT
{ _M_erase_at_end(this->_M_impl._M_start); }
+ private:
+ // RAII guard for allocated storage.
+ struct _Guard_alloc
+ {
+ pointer _M_storage; // Storage to deallocate
+ size_type _M_len;
+ _Base& _M_vect;
+
+ _GLIBCXX20_CONSTEXPR
+ _Guard_alloc(pointer __s, size_type __l, _Base& __vect)
+ : _M_storage(__s), _M_len(__l), _M_vect(__vect)
+ { }
+
+ _GLIBCXX20_CONSTEXPR
+ ~_Guard_alloc()
+ {
+ if (_M_storage)
+ _M_vect._M_deallocate(_M_storage, _M_len);
+ }
+
+ _GLIBCXX20_CONSTEXPR
+ pointer
+ _M_release()
+ {
+ pointer __res = _M_storage;
+ _M_storage = pointer();
+ return __res;
+ }
+
+ private:
+ _Guard_alloc(const _Guard_alloc&);
+ };
+
protected:
/**
* Memory expansion handler. Uses the member allocation function to
@@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
_M_allocate_and_copy(size_type __n,
_ForwardIterator __first, _ForwardIterator __last)
{
- pointer __result = this->_M_allocate(__n);
- __try
- {
- std::__uninitialized_copy_a(__first, __last, __result,
- _M_get_Tp_allocator());
- return __result;
- }
- __catch(...)
- {
- _M_deallocate(__result, __n);
- __throw_exception_again;
- }
+ _Guard_alloc __guard(this->_M_allocate(__n), __n, *this);
+ std::__uninitialized_copy_a
+ (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
+ return __guard._M_release();
}
@@ -1642,13 +1667,18 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
// 438. Ambiguity in the "do the right thing" clause
template<typename _Integer>
void
- _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
+ _M_initialize_dispatch(_Integer __int_n, _Integer __value, __true_type)
{
- this->_M_impl._M_start = _M_allocate(_S_check_init_len(
- static_cast<size_type>(__n), _M_get_Tp_allocator()));
- this->_M_impl._M_end_of_storage =
- this->_M_impl._M_start + static_cast<size_type>(__n);
- _M_fill_initialize(static_cast<size_type>(__n), __value);
+ const size_type __n = static_cast<size_type>(__int_n);
+ pointer __start =
+ _M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
+ _Guard_alloc __guard(__start, __n, *this);
+ this->_M_impl._M_finish =
+ std::__uninitialized_fill_n_a<pointer, size_type, value_type>
+ (__start, __n, __value, _M_get_Tp_allocator());
+ this->_M_impl._M_start = __start;
+ (void) __guard._M_release();
+ this->_M_impl._M_end_of_storage = __start + __n;
}
// Called by the range constructor to implement [23.1.1]/9
@@ -1690,17 +1720,17 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
std::forward_iterator_tag)
{
const size_type __n = std::distance(__first, __last);
- this->_M_impl._M_start
- = this->_M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
- this->_M_impl._M_end_of_storage = this->_M_impl._M_start + __n;
- this->_M_impl._M_finish =
- std::__uninitialized_copy_a(__first, __last,
- this->_M_impl._M_start,
- _M_get_Tp_allocator());
+ pointer __start =
+ this->_M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
+ _Guard_alloc __guard(__start, __n, *this);
+ this->_M_impl._M_finish = std::__uninitialized_copy_a
+ (__first, __last, __start, _M_get_Tp_allocator());
+ this->_M_impl._M_start = __start;
+ (void) __guard._M_release();
+ this->_M_impl._M_end_of_storage = __start + __n;
}
- // Called by the first initialize_dispatch above and by the
- // vector(n,value,a) constructor.
+ // Called by the vector(n,value,a) constructor.
_GLIBCXX20_CONSTEXPR
void
_M_fill_initialize(size_type __n, const value_type& __value)
diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
index 25df060beee..36b27dce7b9 100644
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -467,32 +467,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
pointer __new_start(this->_M_allocate(__len));
pointer __new_finish(__new_start);
- // RAII guard for allocated storage.
- struct _Guard
{
- pointer _M_storage; // Storage to deallocate
- size_type _M_len;
- _Tp_alloc_type& _M_alloc;
-
- _GLIBCXX20_CONSTEXPR
- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
- { }
-
- _GLIBCXX20_CONSTEXPR
- ~_Guard()
- {
- if (_M_storage)
- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
- deallocate(_M_alloc, _M_storage, _M_len);
- }
-
- private:
- _Guard(const _Guard&);
- };
-
- {
- _Guard __guard(__new_start, __len, _M_impl);
+ _Guard_alloc __guard(__new_start, __len, *this);
// The order of the three operations is dictated by the C++11
// case, where the moves could alter a new element belonging
@@ -596,32 +572,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
pointer __new_start(this->_M_allocate(__len));
pointer __new_finish(__new_start);
- // RAII guard for allocated storage.
- struct _Guard
{
- pointer _M_storage; // Storage to deallocate
- size_type _M_len;
- _Tp_alloc_type& _M_alloc;
-
- _GLIBCXX20_CONSTEXPR
- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
- { }
-
- _GLIBCXX20_CONSTEXPR
- ~_Guard()
- {
- if (_M_storage)
- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
- deallocate(_M_alloc, _M_storage, _M_len);
- }
-
- private:
- _Guard(const _Guard&);
- };
-
- {
- _Guard __guard(__new_start, __len, _M_impl);
+ _Guard_alloc __guard(__new_start, __len, *this);
// The order of the three operations is dictated by the C++11
// case, where the moves could alter a new element belonging
@@ -833,32 +785,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
_M_check_len(__n, "vector::_M_default_append");
pointer __new_start(this->_M_allocate(__len));
- // RAII guard for allocated storage.
- struct _Guard
- {
- pointer _M_storage; // Storage to deallocate
- size_type _M_len;
- _Tp_alloc_type& _M_alloc;
-
- _GLIBCXX20_CONSTEXPR
- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
- { }
-
- _GLIBCXX20_CONSTEXPR
- ~_Guard()
- {
- if (_M_storage)
- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
- deallocate(_M_alloc, _M_storage, _M_len);
- }
-
- private:
- _Guard(const _Guard&);
- };
-
{
- _Guard __guard(__new_start, __len, _M_impl);
+ _Guard_alloc __guard(__new_start, __len, *this);
std::__uninitialized_default_n_a(__new_start + __size, __n,
_M_get_Tp_allocator());
diff --git a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc
index 6b3d48f0c92..d732ca8bed8 100644
--- a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc
+++ b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc
@@ -19,7 +19,7 @@
// { dg-do compile }
// { dg-prune-output "cannot convert" }
-// { dg-prune-output "no matching function .*_M_fill_initialize" }
+// { dg-prune-output "no matching function .*__uninitialized_fill_n_a" }
#include <vector>
diff --git a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc
index 65ce2fd30e5..58c4c8f9a73 100644
--- a/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc
+++ b/libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc
@@ -19,7 +19,7 @@
// { dg-do compile }
// { dg-prune-output "cannot convert" }
-// { dg-prune-output "no matching function .*_M_fill_initialize" }
+// { dg-prune-output "no matching function .*__uninitialized_fill_n_a" }
#include <vector>
#include <utility>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] Avoid vector -Wfree-nonheap-object warnings
2024-05-27 4:37 ` François Dumont
@ 2024-05-28 10:30 ` Jonathan Wakely
2024-05-28 20:53 ` François Dumont
0 siblings, 1 reply; 9+ messages in thread
From: Jonathan Wakely @ 2024-05-28 10:30 UTC (permalink / raw)
To: François Dumont; +Cc: libstdc++, gcc-patches
On Mon, 27 May 2024 at 05:37, François Dumont <frs.dumont@gmail.com> wrote:
>
> Here is a new version working also in C++98.
Can we use a different solution that doesn't involve an explicit
template argument list for that __uninitialized_fill_n_a call?
-+ this->_M_impl._M_finish = std::__uninitialized_fill_n_a
++ this->_M_impl._M_finish =
++ std::__uninitialized_fill_n_a<pointer, size_type, value_type>
+ (__start, __n, __value, _M_get_Tp_allocator());
Using _M_fill_initialize solves the problem :-)
>
> Note that I have this failure:
>
> FAIL: 23_containers/vector/types/1.cc -std=gnu++98 (test for excess errors)
>
> but it's already failing on master, my patch do not change anything.
Yes, that's been failing for ages.
>
> Tested under Linux x64,
>
> still ok to commit ?
>
> François
>
> On 24/05/2024 16:17, Jonathan Wakely wrote:
> > On Thu, 23 May 2024 at 18:38, François Dumont <frs.dumont@gmail.com> wrote:
> >>
> >> On 23/05/2024 15:31, Jonathan Wakely wrote:
> >>> On 23/05/24 06:55 +0200, François Dumont wrote:
> >>>> As explained in this email:
> >>>>
> >>>> https://gcc.gnu.org/pipermail/libstdc++/2024-April/058552.html
> >>>>
> >>>> I experimented -Wfree-nonheap-object because of my enhancements on
> >>>> algos.
> >>>>
> >>>> So here is a patch to extend the usage of the _Guard type to other
> >>>> parts of vector.
> >>> Nice, that fixes the warning you were seeing?
> >> Yes ! I indeed forgot to say so :-)
> >>
> >>
> >>> We recently got a bug report about -Wfree-nonheap-object in
> >>> std::vector, but that is coming from _M_realloc_append which already
> >>> uses the RAII guard :-(
> >>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115016
> >> Note that I also had to move call to __uninitialized_copy_a before
> >> assigning this->_M_impl._M_start so get rid of the -Wfree-nonheap-object
> >> warn. But _M_realloc_append is already doing potentially throwing
> >> operations before assigning this->_M_impl so it must be something else.
> >>
> >> Though it made me notice another occurence of _Guard in this method. Now
> >> replaced too in this new patch.
> >>
> >> libstdc++: Use RAII to replace try/catch blocks
> >>
> >> Move _Guard into std::vector declaration and use it to guard all
> >> calls to
> >> vector _M_allocate.
> >>
> >> Doing so the compiler has more visibility on what is done with the
> >> pointers
> >> and do not raise anymore the -Wfree-nonheap-object warning.
> >>
> >> libstdc++-v3/ChangeLog:
> >>
> >> * include/bits/vector.tcc (_Guard): Move all the nested
> >> duplicated class...
> >> * include/bits/stl_vector.h (_Guard_alloc): ...here.
> >> (_M_allocate_and_copy): Use latter.
> >> (_M_initialize_dispatch): Likewise and set _M_finish first
> >> from the result
> >> of __uninitialize_fill_n_a that can throw.
> >> (_M_range_initialize): Likewise.
> >>
> >>>> diff --git a/libstdc++-v3/include/bits/stl_vector.h
> >>>> b/libstdc++-v3/include/bits/stl_vector.h
> >>>> index 31169711a48..4ea74e3339a 100644
> >>>> --- a/libstdc++-v3/include/bits/stl_vector.h
> >>>> +++ b/libstdc++-v3/include/bits/stl_vector.h
> >>>> @@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> >>>> clear() _GLIBCXX_NOEXCEPT
> >>>> { _M_erase_at_end(this->_M_impl._M_start); }
> >>>>
> >>>> + private:
> >>>> + // RAII guard for allocated storage.
> >>>> + struct _Guard
> >>> If it's being defined at class scope instead of locally in a member
> >>> function, I think a better name would be good. Maybe _Ptr_guard or
> >>> _Dealloc_guard or something.
> >> _Guard_alloc chosen.
> >>>> + {
> >>>> + pointer _M_storage; // Storage to deallocate
> >>>> + size_type _M_len;
> >>>> + _Base& _M_vect;
> >>>> +
> >>>> + _GLIBCXX20_CONSTEXPR
> >>>> + _Guard(pointer __s, size_type __l, _Base& __vect)
> >>>> + : _M_storage(__s), _M_len(__l), _M_vect(__vect)
> >>>> + { }
> >>>> +
> >>>> + _GLIBCXX20_CONSTEXPR
> >>>> + ~_Guard()
> >>>> + {
> >>>> + if (_M_storage)
> >>>> + _M_vect._M_deallocate(_M_storage, _M_len);
> >>>> + }
> >>>> +
> >>>> + _GLIBCXX20_CONSTEXPR
> >>>> + pointer
> >>>> + _M_release()
> >>>> + {
> >>>> + pointer __res = _M_storage;
> >>>> + _M_storage = 0;
> >>> I don't think the NullablePointer requirements include assigning 0,
> >>> only from nullptr, which isn't valid in C++98.
> >>>
> >>> https://en.cppreference.com/w/cpp/named_req/NullablePointer
> >>>
> >>> Please use _M_storage = pointer() instead.
> >> I forgot about user fancy pointer, fixed.
> >>
> >>
> >>>> + return __res;
> >>>> + }
> >>>> +
> >>>> + private:
> >>>> + _Guard(const _Guard&);
> >>>> + };
> >>>> +
> >>>> protected:
> >>>> /**
> >>>> * Memory expansion handler. Uses the member allocation
> >>>> function to
> >>>> @@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> >>>> _M_allocate_and_copy(size_type __n,
> >>>> _ForwardIterator __first, _ForwardIterator __last)
> >>>> {
> >>>> - pointer __result = this->_M_allocate(__n);
> >>>> - __try
> >>>> - {
> >>>> - std::__uninitialized_copy_a(__first, __last, __result,
> >>>> - _M_get_Tp_allocator());
> >>>> - return __result;
> >>>> - }
> >>>> - __catch(...)
> >>>> - {
> >>>> - _M_deallocate(__result, __n);
> >>>> - __throw_exception_again;
> >>>> - }
> >>>> + _Guard __guard(this->_M_allocate(__n), __n, *this);
> >>>> + std::__uninitialized_copy_a
> >>>> + (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
> >>>> + return __guard._M_release();
> >>>> }
> >>>>
> >>>>
> >>>> @@ -1642,13 +1667,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> >>>> // 438. Ambiguity in the "do the right thing" clause
> >>>> template<typename _Integer>
> >>>> void
> >>>> - _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
> >>>> + _M_initialize_dispatch(_Integer __int_n, _Integer __value,
> >>>> __true_type)
> >>>> {
> >>>> - this->_M_impl._M_start = _M_allocate(_S_check_init_len(
> >>>> - static_cast<size_type>(__n), _M_get_Tp_allocator()));
> >>>> - this->_M_impl._M_end_of_storage =
> >>>> - this->_M_impl._M_start + static_cast<size_type>(__n);
> >>>> - _M_fill_initialize(static_cast<size_type>(__n), __value);
> >>> Please fix the comment on _M_fill_initialize if you're removing the
> >>> use of it here.
> >> Already done in this initial patch proposal, see below.
> >>
> >>>> + const size_type __n = static_cast<size_type>(__int_n);
> >>>> + _Guard __guard(_M_allocate(_S_check_init_len(
> >>>> + __n, _M_get_Tp_allocator())), __n, *this);
> >>> I think this would be easier to read if the _S_check_init_len call was
> >>> done first, and maybe the allocation too, since we are going to need a
> >>> local __start later anyway. So maybe like this:
> >>>
> >>> template<typename _Integer>
> >>> void
> >>> _M_initialize_dispatch(_Integer __ni, _Integer __value, __true_type)
> >>> {
> >>> const size_type __n = static_cast<size_type>(__ni);
> >>> pointer __start = _M_allocate(_S_check_init_len(__n),
> >>> _M_get_Tp_allocator());
> >>> _Guard __guard(__start, __n, *this);
> >>> this->_M_impl._M_start = __start;
> >>> _M_fill_initialize(__n, __value);
> >>> this->_M_impl._M_end_of_storage = __start + __n;
> >>> (void) __guard._M_release();
> >>> }
> >>>
> >>> Or inline the __uninitialized_fill_n_a call if you want to (but then
> >>> fix the comment on _M_fill_initialize). Inlining it does make this
> >>> function more consistent with the next one, which calls
> >>> __uninitialized_copy_a directly.
> >> Yes, this is why I called __uninitialized_fill_n_a instead and also to
> >> do so *before* assigning _M_impl._M_start.
> >>
> >>
> >>>> - // Called by the first initialize_dispatch above and by the
> >>>> - // vector(n,value,a) constructor.
> >>>> + // Called by the vector(n,value,a) constructor.
> >> See, it's here :-)
> > Doh! Sorry, I'm not sure how I missed that.
> >
> >> Ok to commit ?
> > OK for trunk, thanks!
> >
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] Avoid vector -Wfree-nonheap-object warnings
2024-05-28 10:30 ` Jonathan Wakely
@ 2024-05-28 20:53 ` François Dumont
2024-05-29 9:35 ` Jonathan Wakely
0 siblings, 1 reply; 9+ messages in thread
From: François Dumont @ 2024-05-28 20:53 UTC (permalink / raw)
To: Jonathan Wakely; +Cc: libstdc++, gcc-patches
[-- Attachment #1: Type: text/plain, Size: 9583 bytes --]
I can indeed restore _M_initialize_dispatch as it was before. It was not
fixing my initial problem. I simply kept the code simplification.
libstdc++: Use RAII to replace try/catch blocks
Move _Guard into std::vector declaration and use it to guard all
calls to
vector _M_allocate.
Doing so the compiler has more visibility on what is done with the
pointers
and do not raise anymore the -Wfree-nonheap-object warning.
libstdc++-v3/ChangeLog:
* include/bits/vector.tcc (_Guard): Move all the nested
duplicated class...
* include/bits/stl_vector.h (_Guard_alloc): ...here and rename.
(_M_allocate_and_copy): Use latter.
(_M_initialize_dispatch): Small code simplification.
(_M_range_initialize): Likewise and set _M_finish first
from the result
of __uninitialize_fill_n_a that can throw.
Tested under Linux x86_64.
Ok to commit ?
François
On 28/05/2024 12:30, Jonathan Wakely wrote:
> On Mon, 27 May 2024 at 05:37, François Dumont <frs.dumont@gmail.com> wrote:
>> Here is a new version working also in C++98.
> Can we use a different solution that doesn't involve an explicit
> template argument list for that __uninitialized_fill_n_a call?
>
> -+ this->_M_impl._M_finish = std::__uninitialized_fill_n_a
> ++ this->_M_impl._M_finish =
> ++ std::__uninitialized_fill_n_a<pointer, size_type, value_type>
> + (__start, __n, __value, _M_get_Tp_allocator());
>
> Using _M_fill_initialize solves the problem :-)
>
>
>
>> Note that I have this failure:
>>
>> FAIL: 23_containers/vector/types/1.cc -std=gnu++98 (test for excess errors)
>>
>> but it's already failing on master, my patch do not change anything.
> Yes, that's been failing for ages.
>
>> Tested under Linux x64,
>>
>> still ok to commit ?
>>
>> François
>>
>> On 24/05/2024 16:17, Jonathan Wakely wrote:
>>> On Thu, 23 May 2024 at 18:38, François Dumont <frs.dumont@gmail.com> wrote:
>>>> On 23/05/2024 15:31, Jonathan Wakely wrote:
>>>>> On 23/05/24 06:55 +0200, François Dumont wrote:
>>>>>> As explained in this email:
>>>>>>
>>>>>> https://gcc.gnu.org/pipermail/libstdc++/2024-April/058552.html
>>>>>>
>>>>>> I experimented -Wfree-nonheap-object because of my enhancements on
>>>>>> algos.
>>>>>>
>>>>>> So here is a patch to extend the usage of the _Guard type to other
>>>>>> parts of vector.
>>>>> Nice, that fixes the warning you were seeing?
>>>> Yes ! I indeed forgot to say so :-)
>>>>
>>>>
>>>>> We recently got a bug report about -Wfree-nonheap-object in
>>>>> std::vector, but that is coming from _M_realloc_append which already
>>>>> uses the RAII guard :-(
>>>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115016
>>>> Note that I also had to move call to __uninitialized_copy_a before
>>>> assigning this->_M_impl._M_start so get rid of the -Wfree-nonheap-object
>>>> warn. But _M_realloc_append is already doing potentially throwing
>>>> operations before assigning this->_M_impl so it must be something else.
>>>>
>>>> Though it made me notice another occurence of _Guard in this method. Now
>>>> replaced too in this new patch.
>>>>
>>>> libstdc++: Use RAII to replace try/catch blocks
>>>>
>>>> Move _Guard into std::vector declaration and use it to guard all
>>>> calls to
>>>> vector _M_allocate.
>>>>
>>>> Doing so the compiler has more visibility on what is done with the
>>>> pointers
>>>> and do not raise anymore the -Wfree-nonheap-object warning.
>>>>
>>>> libstdc++-v3/ChangeLog:
>>>>
>>>> * include/bits/vector.tcc (_Guard): Move all the nested
>>>> duplicated class...
>>>> * include/bits/stl_vector.h (_Guard_alloc): ...here.
>>>> (_M_allocate_and_copy): Use latter.
>>>> (_M_initialize_dispatch): Likewise and set _M_finish first
>>>> from the result
>>>> of __uninitialize_fill_n_a that can throw.
>>>> (_M_range_initialize): Likewise.
>>>>
>>>>>> diff --git a/libstdc++-v3/include/bits/stl_vector.h
>>>>>> b/libstdc++-v3/include/bits/stl_vector.h
>>>>>> index 31169711a48..4ea74e3339a 100644
>>>>>> --- a/libstdc++-v3/include/bits/stl_vector.h
>>>>>> +++ b/libstdc++-v3/include/bits/stl_vector.h
>>>>>> @@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>>>>>> clear() _GLIBCXX_NOEXCEPT
>>>>>> { _M_erase_at_end(this->_M_impl._M_start); }
>>>>>>
>>>>>> + private:
>>>>>> + // RAII guard for allocated storage.
>>>>>> + struct _Guard
>>>>> If it's being defined at class scope instead of locally in a member
>>>>> function, I think a better name would be good. Maybe _Ptr_guard or
>>>>> _Dealloc_guard or something.
>>>> _Guard_alloc chosen.
>>>>>> + {
>>>>>> + pointer _M_storage; // Storage to deallocate
>>>>>> + size_type _M_len;
>>>>>> + _Base& _M_vect;
>>>>>> +
>>>>>> + _GLIBCXX20_CONSTEXPR
>>>>>> + _Guard(pointer __s, size_type __l, _Base& __vect)
>>>>>> + : _M_storage(__s), _M_len(__l), _M_vect(__vect)
>>>>>> + { }
>>>>>> +
>>>>>> + _GLIBCXX20_CONSTEXPR
>>>>>> + ~_Guard()
>>>>>> + {
>>>>>> + if (_M_storage)
>>>>>> + _M_vect._M_deallocate(_M_storage, _M_len);
>>>>>> + }
>>>>>> +
>>>>>> + _GLIBCXX20_CONSTEXPR
>>>>>> + pointer
>>>>>> + _M_release()
>>>>>> + {
>>>>>> + pointer __res = _M_storage;
>>>>>> + _M_storage = 0;
>>>>> I don't think the NullablePointer requirements include assigning 0,
>>>>> only from nullptr, which isn't valid in C++98.
>>>>>
>>>>> https://en.cppreference.com/w/cpp/named_req/NullablePointer
>>>>>
>>>>> Please use _M_storage = pointer() instead.
>>>> I forgot about user fancy pointer, fixed.
>>>>
>>>>
>>>>>> + return __res;
>>>>>> + }
>>>>>> +
>>>>>> + private:
>>>>>> + _Guard(const _Guard&);
>>>>>> + };
>>>>>> +
>>>>>> protected:
>>>>>> /**
>>>>>> * Memory expansion handler. Uses the member allocation
>>>>>> function to
>>>>>> @@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>>>>>> _M_allocate_and_copy(size_type __n,
>>>>>> _ForwardIterator __first, _ForwardIterator __last)
>>>>>> {
>>>>>> - pointer __result = this->_M_allocate(__n);
>>>>>> - __try
>>>>>> - {
>>>>>> - std::__uninitialized_copy_a(__first, __last, __result,
>>>>>> - _M_get_Tp_allocator());
>>>>>> - return __result;
>>>>>> - }
>>>>>> - __catch(...)
>>>>>> - {
>>>>>> - _M_deallocate(__result, __n);
>>>>>> - __throw_exception_again;
>>>>>> - }
>>>>>> + _Guard __guard(this->_M_allocate(__n), __n, *this);
>>>>>> + std::__uninitialized_copy_a
>>>>>> + (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
>>>>>> + return __guard._M_release();
>>>>>> }
>>>>>>
>>>>>>
>>>>>> @@ -1642,13 +1667,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
>>>>>> // 438. Ambiguity in the "do the right thing" clause
>>>>>> template<typename _Integer>
>>>>>> void
>>>>>> - _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
>>>>>> + _M_initialize_dispatch(_Integer __int_n, _Integer __value,
>>>>>> __true_type)
>>>>>> {
>>>>>> - this->_M_impl._M_start = _M_allocate(_S_check_init_len(
>>>>>> - static_cast<size_type>(__n), _M_get_Tp_allocator()));
>>>>>> - this->_M_impl._M_end_of_storage =
>>>>>> - this->_M_impl._M_start + static_cast<size_type>(__n);
>>>>>> - _M_fill_initialize(static_cast<size_type>(__n), __value);
>>>>> Please fix the comment on _M_fill_initialize if you're removing the
>>>>> use of it here.
>>>> Already done in this initial patch proposal, see below.
>>>>
>>>>>> + const size_type __n = static_cast<size_type>(__int_n);
>>>>>> + _Guard __guard(_M_allocate(_S_check_init_len(
>>>>>> + __n, _M_get_Tp_allocator())), __n, *this);
>>>>> I think this would be easier to read if the _S_check_init_len call was
>>>>> done first, and maybe the allocation too, since we are going to need a
>>>>> local __start later anyway. So maybe like this:
>>>>>
>>>>> template<typename _Integer>
>>>>> void
>>>>> _M_initialize_dispatch(_Integer __ni, _Integer __value, __true_type)
>>>>> {
>>>>> const size_type __n = static_cast<size_type>(__ni);
>>>>> pointer __start = _M_allocate(_S_check_init_len(__n),
>>>>> _M_get_Tp_allocator());
>>>>> _Guard __guard(__start, __n, *this);
>>>>> this->_M_impl._M_start = __start;
>>>>> _M_fill_initialize(__n, __value);
>>>>> this->_M_impl._M_end_of_storage = __start + __n;
>>>>> (void) __guard._M_release();
>>>>> }
>>>>>
>>>>> Or inline the __uninitialized_fill_n_a call if you want to (but then
>>>>> fix the comment on _M_fill_initialize). Inlining it does make this
>>>>> function more consistent with the next one, which calls
>>>>> __uninitialized_copy_a directly.
>>>> Yes, this is why I called __uninitialized_fill_n_a instead and also to
>>>> do so *before* assigning _M_impl._M_start.
>>>>
>>>>
>>>>>> - // Called by the first initialize_dispatch above and by the
>>>>>> - // vector(n,value,a) constructor.
>>>>>> + // Called by the vector(n,value,a) constructor.
>>>> See, it's here :-)
>>> Doh! Sorry, I'm not sure how I missed that.
>>>
>>>> Ok to commit ?
>>> OK for trunk, thanks!
>>>
[-- Attachment #2: vector_patch.txt --]
[-- Type: text/plain, Size: 6607 bytes --]
diff --git a/libstdc++-v3/include/bits/stl_vector.h b/libstdc++-v3/include/bits/stl_vector.h
index 31169711a48..182ad41ed94 100644
--- a/libstdc++-v3/include/bits/stl_vector.h
+++ b/libstdc++-v3/include/bits/stl_vector.h
@@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
clear() _GLIBCXX_NOEXCEPT
{ _M_erase_at_end(this->_M_impl._M_start); }
+ private:
+ // RAII guard for allocated storage.
+ struct _Guard_alloc
+ {
+ pointer _M_storage; // Storage to deallocate
+ size_type _M_len;
+ _Base& _M_vect;
+
+ _GLIBCXX20_CONSTEXPR
+ _Guard_alloc(pointer __s, size_type __l, _Base& __vect)
+ : _M_storage(__s), _M_len(__l), _M_vect(__vect)
+ { }
+
+ _GLIBCXX20_CONSTEXPR
+ ~_Guard_alloc()
+ {
+ if (_M_storage)
+ _M_vect._M_deallocate(_M_storage, _M_len);
+ }
+
+ _GLIBCXX20_CONSTEXPR
+ pointer
+ _M_release()
+ {
+ pointer __res = _M_storage;
+ _M_storage = pointer();
+ return __res;
+ }
+
+ private:
+ _Guard_alloc(const _Guard_alloc&);
+ };
+
protected:
/**
* Memory expansion handler. Uses the member allocation function to
@@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
_M_allocate_and_copy(size_type __n,
_ForwardIterator __first, _ForwardIterator __last)
{
- pointer __result = this->_M_allocate(__n);
- __try
- {
- std::__uninitialized_copy_a(__first, __last, __result,
- _M_get_Tp_allocator());
- return __result;
- }
- __catch(...)
- {
- _M_deallocate(__result, __n);
- __throw_exception_again;
- }
+ _Guard_alloc __guard(this->_M_allocate(__n), __n, *this);
+ std::__uninitialized_copy_a
+ (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
+ return __guard._M_release();
}
@@ -1642,13 +1667,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
// 438. Ambiguity in the "do the right thing" clause
template<typename _Integer>
void
- _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
+ _M_initialize_dispatch(_Integer __int_n, _Integer __value, __true_type)
{
- this->_M_impl._M_start = _M_allocate(_S_check_init_len(
- static_cast<size_type>(__n), _M_get_Tp_allocator()));
- this->_M_impl._M_end_of_storage =
- this->_M_impl._M_start + static_cast<size_type>(__n);
- _M_fill_initialize(static_cast<size_type>(__n), __value);
+ const size_type __n = static_cast<size_type>(__int_n);
+ pointer __start =
+ _M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
+ this->_M_impl._M_start = __start;
+ this->_M_impl._M_end_of_storage = __start + __n;
+ _M_fill_initialize(__n, __value);
}
// Called by the range constructor to implement [23.1.1]/9
@@ -1690,13 +1716,14 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
std::forward_iterator_tag)
{
const size_type __n = std::distance(__first, __last);
- this->_M_impl._M_start
- = this->_M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
- this->_M_impl._M_end_of_storage = this->_M_impl._M_start + __n;
- this->_M_impl._M_finish =
- std::__uninitialized_copy_a(__first, __last,
- this->_M_impl._M_start,
- _M_get_Tp_allocator());
+ pointer __start =
+ this->_M_allocate(_S_check_init_len(__n, _M_get_Tp_allocator()));
+ _Guard_alloc __guard(__start, __n, *this);
+ this->_M_impl._M_finish = std::__uninitialized_copy_a
+ (__first, __last, __start, _M_get_Tp_allocator());
+ this->_M_impl._M_start = __start;
+ (void) __guard._M_release();
+ this->_M_impl._M_end_of_storage = __start + __n;
}
// Called by the first initialize_dispatch above and by the
diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
index 25df060beee..36b27dce7b9 100644
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -467,32 +467,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
pointer __new_start(this->_M_allocate(__len));
pointer __new_finish(__new_start);
- // RAII guard for allocated storage.
- struct _Guard
{
- pointer _M_storage; // Storage to deallocate
- size_type _M_len;
- _Tp_alloc_type& _M_alloc;
-
- _GLIBCXX20_CONSTEXPR
- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
- { }
-
- _GLIBCXX20_CONSTEXPR
- ~_Guard()
- {
- if (_M_storage)
- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
- deallocate(_M_alloc, _M_storage, _M_len);
- }
-
- private:
- _Guard(const _Guard&);
- };
-
- {
- _Guard __guard(__new_start, __len, _M_impl);
+ _Guard_alloc __guard(__new_start, __len, *this);
// The order of the three operations is dictated by the C++11
// case, where the moves could alter a new element belonging
@@ -596,32 +572,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
pointer __new_start(this->_M_allocate(__len));
pointer __new_finish(__new_start);
- // RAII guard for allocated storage.
- struct _Guard
{
- pointer _M_storage; // Storage to deallocate
- size_type _M_len;
- _Tp_alloc_type& _M_alloc;
-
- _GLIBCXX20_CONSTEXPR
- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
- { }
-
- _GLIBCXX20_CONSTEXPR
- ~_Guard()
- {
- if (_M_storage)
- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
- deallocate(_M_alloc, _M_storage, _M_len);
- }
-
- private:
- _Guard(const _Guard&);
- };
-
- {
- _Guard __guard(__new_start, __len, _M_impl);
+ _Guard_alloc __guard(__new_start, __len, *this);
// The order of the three operations is dictated by the C++11
// case, where the moves could alter a new element belonging
@@ -833,32 +785,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
_M_check_len(__n, "vector::_M_default_append");
pointer __new_start(this->_M_allocate(__len));
- // RAII guard for allocated storage.
- struct _Guard
- {
- pointer _M_storage; // Storage to deallocate
- size_type _M_len;
- _Tp_alloc_type& _M_alloc;
-
- _GLIBCXX20_CONSTEXPR
- _Guard(pointer __s, size_type __l, _Tp_alloc_type& __a)
- : _M_storage(__s), _M_len(__l), _M_alloc(__a)
- { }
-
- _GLIBCXX20_CONSTEXPR
- ~_Guard()
- {
- if (_M_storage)
- __gnu_cxx::__alloc_traits<_Tp_alloc_type>::
- deallocate(_M_alloc, _M_storage, _M_len);
- }
-
- private:
- _Guard(const _Guard&);
- };
-
{
- _Guard __guard(__new_start, __len, _M_impl);
+ _Guard_alloc __guard(__new_start, __len, *this);
std::__uninitialized_default_n_a(__new_start + __size, __n,
_M_get_Tp_allocator());
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] Avoid vector -Wfree-nonheap-object warnings
2024-05-28 20:53 ` François Dumont
@ 2024-05-29 9:35 ` Jonathan Wakely
0 siblings, 0 replies; 9+ messages in thread
From: Jonathan Wakely @ 2024-05-29 9:35 UTC (permalink / raw)
To: François Dumont; +Cc: Jonathan Wakely, libstdc++, gcc-patches
On Tue, 28 May 2024 at 21:55, François Dumont <frs.dumont@gmail.com> wrote:
>
> I can indeed restore _M_initialize_dispatch as it was before. It was not
> fixing my initial problem. I simply kept the code simplification.
>
> libstdc++: Use RAII to replace try/catch blocks
>
> Move _Guard into std::vector declaration and use it to guard all
> calls to
> vector _M_allocate.
>
> Doing so the compiler has more visibility on what is done with the
> pointers
> and do not raise anymore the -Wfree-nonheap-object warning.
>
> libstdc++-v3/ChangeLog:
>
> * include/bits/vector.tcc (_Guard): Move all the nested
> duplicated class...
> * include/bits/stl_vector.h (_Guard_alloc): ...here and rename.
> (_M_allocate_and_copy): Use latter.
> (_M_initialize_dispatch): Small code simplification.
> (_M_range_initialize): Likewise and set _M_finish first
> from the result
> of __uninitialize_fill_n_a that can throw.
>
> Tested under Linux x86_64.
>
> Ok to commit ?
OK, thanks
>
> François
>
> On 28/05/2024 12:30, Jonathan Wakely wrote:
> > On Mon, 27 May 2024 at 05:37, François Dumont <frs.dumont@gmail.com> wrote:
> >> Here is a new version working also in C++98.
> > Can we use a different solution that doesn't involve an explicit
> > template argument list for that __uninitialized_fill_n_a call?
> >
> > -+ this->_M_impl._M_finish = std::__uninitialized_fill_n_a
> > ++ this->_M_impl._M_finish =
> > ++ std::__uninitialized_fill_n_a<pointer, size_type, value_type>
> > + (__start, __n, __value, _M_get_Tp_allocator());
> >
> > Using _M_fill_initialize solves the problem :-)
> >
> >
> >
> >> Note that I have this failure:
> >>
> >> FAIL: 23_containers/vector/types/1.cc -std=gnu++98 (test for excess errors)
> >>
> >> but it's already failing on master, my patch do not change anything.
> > Yes, that's been failing for ages.
> >
> >> Tested under Linux x64,
> >>
> >> still ok to commit ?
> >>
> >> François
> >>
> >> On 24/05/2024 16:17, Jonathan Wakely wrote:
> >>> On Thu, 23 May 2024 at 18:38, François Dumont <frs.dumont@gmail.com> wrote:
> >>>> On 23/05/2024 15:31, Jonathan Wakely wrote:
> >>>>> On 23/05/24 06:55 +0200, François Dumont wrote:
> >>>>>> As explained in this email:
> >>>>>>
> >>>>>> https://gcc.gnu.org/pipermail/libstdc++/2024-April/058552.html
> >>>>>>
> >>>>>> I experimented -Wfree-nonheap-object because of my enhancements on
> >>>>>> algos.
> >>>>>>
> >>>>>> So here is a patch to extend the usage of the _Guard type to other
> >>>>>> parts of vector.
> >>>>> Nice, that fixes the warning you were seeing?
> >>>> Yes ! I indeed forgot to say so :-)
> >>>>
> >>>>
> >>>>> We recently got a bug report about -Wfree-nonheap-object in
> >>>>> std::vector, but that is coming from _M_realloc_append which already
> >>>>> uses the RAII guard :-(
> >>>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115016
> >>>> Note that I also had to move call to __uninitialized_copy_a before
> >>>> assigning this->_M_impl._M_start so get rid of the -Wfree-nonheap-object
> >>>> warn. But _M_realloc_append is already doing potentially throwing
> >>>> operations before assigning this->_M_impl so it must be something else.
> >>>>
> >>>> Though it made me notice another occurence of _Guard in this method. Now
> >>>> replaced too in this new patch.
> >>>>
> >>>> libstdc++: Use RAII to replace try/catch blocks
> >>>>
> >>>> Move _Guard into std::vector declaration and use it to guard all
> >>>> calls to
> >>>> vector _M_allocate.
> >>>>
> >>>> Doing so the compiler has more visibility on what is done with the
> >>>> pointers
> >>>> and do not raise anymore the -Wfree-nonheap-object warning.
> >>>>
> >>>> libstdc++-v3/ChangeLog:
> >>>>
> >>>> * include/bits/vector.tcc (_Guard): Move all the nested
> >>>> duplicated class...
> >>>> * include/bits/stl_vector.h (_Guard_alloc): ...here.
> >>>> (_M_allocate_and_copy): Use latter.
> >>>> (_M_initialize_dispatch): Likewise and set _M_finish first
> >>>> from the result
> >>>> of __uninitialize_fill_n_a that can throw.
> >>>> (_M_range_initialize): Likewise.
> >>>>
> >>>>>> diff --git a/libstdc++-v3/include/bits/stl_vector.h
> >>>>>> b/libstdc++-v3/include/bits/stl_vector.h
> >>>>>> index 31169711a48..4ea74e3339a 100644
> >>>>>> --- a/libstdc++-v3/include/bits/stl_vector.h
> >>>>>> +++ b/libstdc++-v3/include/bits/stl_vector.h
> >>>>>> @@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> >>>>>> clear() _GLIBCXX_NOEXCEPT
> >>>>>> { _M_erase_at_end(this->_M_impl._M_start); }
> >>>>>>
> >>>>>> + private:
> >>>>>> + // RAII guard for allocated storage.
> >>>>>> + struct _Guard
> >>>>> If it's being defined at class scope instead of locally in a member
> >>>>> function, I think a better name would be good. Maybe _Ptr_guard or
> >>>>> _Dealloc_guard or something.
> >>>> _Guard_alloc chosen.
> >>>>>> + {
> >>>>>> + pointer _M_storage; // Storage to deallocate
> >>>>>> + size_type _M_len;
> >>>>>> + _Base& _M_vect;
> >>>>>> +
> >>>>>> + _GLIBCXX20_CONSTEXPR
> >>>>>> + _Guard(pointer __s, size_type __l, _Base& __vect)
> >>>>>> + : _M_storage(__s), _M_len(__l), _M_vect(__vect)
> >>>>>> + { }
> >>>>>> +
> >>>>>> + _GLIBCXX20_CONSTEXPR
> >>>>>> + ~_Guard()
> >>>>>> + {
> >>>>>> + if (_M_storage)
> >>>>>> + _M_vect._M_deallocate(_M_storage, _M_len);
> >>>>>> + }
> >>>>>> +
> >>>>>> + _GLIBCXX20_CONSTEXPR
> >>>>>> + pointer
> >>>>>> + _M_release()
> >>>>>> + {
> >>>>>> + pointer __res = _M_storage;
> >>>>>> + _M_storage = 0;
> >>>>> I don't think the NullablePointer requirements include assigning 0,
> >>>>> only from nullptr, which isn't valid in C++98.
> >>>>>
> >>>>> https://en.cppreference.com/w/cpp/named_req/NullablePointer
> >>>>>
> >>>>> Please use _M_storage = pointer() instead.
> >>>> I forgot about user fancy pointer, fixed.
> >>>>
> >>>>
> >>>>>> + return __res;
> >>>>>> + }
> >>>>>> +
> >>>>>> + private:
> >>>>>> + _Guard(const _Guard&);
> >>>>>> + };
> >>>>>> +
> >>>>>> protected:
> >>>>>> /**
> >>>>>> * Memory expansion handler. Uses the member allocation
> >>>>>> function to
> >>>>>> @@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> >>>>>> _M_allocate_and_copy(size_type __n,
> >>>>>> _ForwardIterator __first, _ForwardIterator __last)
> >>>>>> {
> >>>>>> - pointer __result = this->_M_allocate(__n);
> >>>>>> - __try
> >>>>>> - {
> >>>>>> - std::__uninitialized_copy_a(__first, __last, __result,
> >>>>>> - _M_get_Tp_allocator());
> >>>>>> - return __result;
> >>>>>> - }
> >>>>>> - __catch(...)
> >>>>>> - {
> >>>>>> - _M_deallocate(__result, __n);
> >>>>>> - __throw_exception_again;
> >>>>>> - }
> >>>>>> + _Guard __guard(this->_M_allocate(__n), __n, *this);
> >>>>>> + std::__uninitialized_copy_a
> >>>>>> + (__first, __last, __guard._M_storage, _M_get_Tp_allocator());
> >>>>>> + return __guard._M_release();
> >>>>>> }
> >>>>>>
> >>>>>>
> >>>>>> @@ -1642,13 +1667,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
> >>>>>> // 438. Ambiguity in the "do the right thing" clause
> >>>>>> template<typename _Integer>
> >>>>>> void
> >>>>>> - _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type)
> >>>>>> + _M_initialize_dispatch(_Integer __int_n, _Integer __value,
> >>>>>> __true_type)
> >>>>>> {
> >>>>>> - this->_M_impl._M_start = _M_allocate(_S_check_init_len(
> >>>>>> - static_cast<size_type>(__n), _M_get_Tp_allocator()));
> >>>>>> - this->_M_impl._M_end_of_storage =
> >>>>>> - this->_M_impl._M_start + static_cast<size_type>(__n);
> >>>>>> - _M_fill_initialize(static_cast<size_type>(__n), __value);
> >>>>> Please fix the comment on _M_fill_initialize if you're removing the
> >>>>> use of it here.
> >>>> Already done in this initial patch proposal, see below.
> >>>>
> >>>>>> + const size_type __n = static_cast<size_type>(__int_n);
> >>>>>> + _Guard __guard(_M_allocate(_S_check_init_len(
> >>>>>> + __n, _M_get_Tp_allocator())), __n, *this);
> >>>>> I think this would be easier to read if the _S_check_init_len call was
> >>>>> done first, and maybe the allocation too, since we are going to need a
> >>>>> local __start later anyway. So maybe like this:
> >>>>>
> >>>>> template<typename _Integer>
> >>>>> void
> >>>>> _M_initialize_dispatch(_Integer __ni, _Integer __value, __true_type)
> >>>>> {
> >>>>> const size_type __n = static_cast<size_type>(__ni);
> >>>>> pointer __start = _M_allocate(_S_check_init_len(__n),
> >>>>> _M_get_Tp_allocator());
> >>>>> _Guard __guard(__start, __n, *this);
> >>>>> this->_M_impl._M_start = __start;
> >>>>> _M_fill_initialize(__n, __value);
> >>>>> this->_M_impl._M_end_of_storage = __start + __n;
> >>>>> (void) __guard._M_release();
> >>>>> }
> >>>>>
> >>>>> Or inline the __uninitialized_fill_n_a call if you want to (but then
> >>>>> fix the comment on _M_fill_initialize). Inlining it does make this
> >>>>> function more consistent with the next one, which calls
> >>>>> __uninitialized_copy_a directly.
> >>>> Yes, this is why I called __uninitialized_fill_n_a instead and also to
> >>>> do so *before* assigning _M_impl._M_start.
> >>>>
> >>>>
> >>>>>> - // Called by the first initialize_dispatch above and by the
> >>>>>> - // vector(n,value,a) constructor.
> >>>>>> + // Called by the vector(n,value,a) constructor.
> >>>> See, it's here :-)
> >>> Doh! Sorry, I'm not sure how I missed that.
> >>>
> >>>> Ok to commit ?
> >>> OK for trunk, thanks!
> >>>
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2024-05-29 9:35 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-05-23 4:55 [PATCH] Avoid vector -Wfree-nonheap-object warnings François Dumont
2024-05-23 13:31 ` Jonathan Wakely
2024-05-23 17:37 ` François Dumont
2024-05-24 14:17 ` Jonathan Wakely
2024-05-25 9:59 ` François Dumont
2024-05-27 4:37 ` François Dumont
2024-05-28 10:30 ` Jonathan Wakely
2024-05-28 20:53 ` François Dumont
2024-05-29 9:35 ` Jonathan Wakely
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