[RFC] c++: lambda mangling alias issues [PR107897]
Checks
Commit Message
Tested x86_64-pc-linux-gnu. Does this look good, or do we want to factor the
flag clearing into a symtab_node counterpart to cgraph_node::reset?
-- 8< --
In 107897, by the time we are looking at the mangling clash, the
alias has already been removed from the symbol table by analyze_functions,
so we can't look at n->cpp_implicit_alias. So just assume that it's an
alias if it's internal.
In 108887 the problem is that removing the mangling alias from the symbol
table confuses analyze_functions, because it ended up as first_analyzed
somehow, so it becomes a dangling pointer. Fixed by clearing various flags
to neutralize the alias.
PR c++/107897
PR c++/108887
gcc/cp/ChangeLog:
* decl2.cc (record_mangling): Improve symbol table handling.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-lambda3.C: Use -flto if supported.
* g++.dg/cpp0x/lambda/lambda-mangle7.C: New test.
---
gcc/cp/decl2.cc | 25 +++++--
.../g++.dg/cpp0x/lambda/lambda-mangle7.C | 70 +++++++++++++++++++
gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C | 1 +
3 files changed, 91 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C
base-commit: 4f181f9c7ee3efc509d185fdfda33be9018f1611
Comments
> Tested x86_64-pc-linux-gnu. Does this look good, or do we want to factor the
> flag clearing into a symtab_node counterpart to cgraph_node::reset?
>
> -- 8< --
>
> In 107897, by the time we are looking at the mangling clash, the
> alias has already been removed from the symbol table by analyze_functions,
> so we can't look at n->cpp_implicit_alias. So just assume that it's an
> alias if it's internal.
>
> In 108887 the problem is that removing the mangling alias from the symbol
> table confuses analyze_functions, because it ended up as first_analyzed
> somehow, so it becomes a dangling pointer. Fixed by clearing various flags
> to neutralize the alias.
>
> PR c++/107897
> PR c++/108887
>
> gcc/cp/ChangeLog:
>
> * decl2.cc (record_mangling): Improve symbol table handling.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/cpp2a/concepts-lambda3.C: Use -flto if supported.
> * g++.dg/cpp0x/lambda/lambda-mangle7.C: New test.
> ---
> gcc/cp/decl2.cc | 25 +++++--
> .../g++.dg/cpp0x/lambda/lambda-mangle7.C | 70 +++++++++++++++++++
> gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C | 1 +
> 3 files changed, 91 insertions(+), 5 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C
>
> diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
> index 387e24542cd..e6e58b08de4 100644
> --- a/gcc/cp/decl2.cc
> +++ b/gcc/cp/decl2.cc
> @@ -4742,15 +4742,30 @@ record_mangling (tree decl, bool need_warning)
> = mangled_decls->find_slot_with_hash (id, IDENTIFIER_HASH_VALUE (id),
> INSERT);
>
> - /* If this is already an alias, remove the alias, because the real
> + /* If this is already an alias, cancel the alias, because the real
> decl takes precedence. */
> if (*slot && DECL_ARTIFICIAL (*slot) && DECL_IGNORED_P (*slot))
> - if (symtab_node *n = symtab_node::get (*slot))
> - if (n->cpp_implicit_alias)
> + {
> + if (symtab_node *n = symtab_node::get (*slot))
> {
> - n->remove ();
> - *slot = NULL_TREE;
> + if (n->cpp_implicit_alias)
> + {
> + /* Actually removing the node isn't safe if other code is already
> + holding a pointer to it, so just neutralize it. */
> + n->remove_from_same_comdat_group ();
> + n->analyzed = false;
> + n->definition = false;
> + n->alias = false;
> + n->cpp_implicit_alias = false;
We have n->reset () for that which is used in similar situation when
frontends overwrites extern inline function by its different offline
implementation.
reset doesn't call remove_from_same_comdat_group probably because it was
never used on anything in comdat group. So I think it would make sense
to call n->reset() here and add remove_from_same_comdat_group into that.
OK with that change.
Honza
> + }
> }
> + else
> + /* analyze_functions might have already removed the alias from the
> + symbol table if it's internal. */
> + gcc_checking_assert (!TREE_PUBLIC (*slot));
> +
> + *slot = NULL_TREE;
> + }
>
> if (!*slot)
> *slot = decl;
> diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C
> new file mode 100644
> index 00000000000..c7946a2be08
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C
> @@ -0,0 +1,70 @@
> +// PR c++/108887
> +// { dg-do compile { target c++11 } }
> +
> +template <int __v> struct integral_constant {
> + static constexpr int value = __v;
> +};
> +using false_type = integral_constant<false>;
> +template <bool, bool, typename...> struct __result_of_impl;
> +template <typename _Functor, typename... _ArgTypes>
> +struct __result_of_impl<false, false, _Functor, _ArgTypes...> {
> + typedef decltype(0) type;
> +};
> +template <typename... _ArgTypes>
> +struct __invoke_result
> + : __result_of_impl<false_type::value, false_type::value, _ArgTypes...> {};
> +template <typename, typename _Fn, typename... _Args>
> +void __invoke_impl(_Fn __f, _Args... __args) {
> + __f(__args...);
> +}
> +template <typename, typename _Callable, typename... _Args>
> +void __invoke_r(_Callable __fn, _Args... __args) {
> + using __result = __invoke_result<_Args...>;
> + using __type = typename __result::type;
> + __invoke_impl<__type>(__fn, __args...);
> +}
> +struct QString {
> + QString(const char *);
> +};
> +template <typename> class function;
> +template <typename _Functor> struct _Base_manager {
> + static _Functor _M_get_pointer(int) { __builtin_abort (); }
> +};
> +template <typename, typename> class _Function_handler;
> +template <typename _Res, typename _Functor, typename... _ArgTypes>
> +struct _Function_handler<_Res(_ArgTypes...), _Functor> {
> + using _Base = _Base_manager<_Functor>;
> + static _Res _M_invoke(const int &__functor, _ArgTypes &&...__args) {
> + auto __trans_tmp_1 = _Base::_M_get_pointer(__functor);
> + __invoke_r<_Res>(__trans_tmp_1, __args...);
> + }
> +};
> +template <typename _Res, typename... _ArgTypes>
> +struct function<_Res(_ArgTypes...)> {
> + template <typename _Functor>
> + using _Handler = _Function_handler<_Res(_ArgTypes...), _Functor>;
> + template <typename _Functor> function(_Functor) {
> + using _My_handler = _Handler<_Functor>;
> + _M_invoker = _My_handler::_M_invoke;
> + }
> + using _Invoker_type = _Res (*)(const int &, _ArgTypes &&...);
> + _Invoker_type _M_invoker;
> +};
> +struct QRegularExpression {
> + QRegularExpression(QString);
> +};
> +struct AbstractAccount {
> + void get(function<void(AbstractAccount *)>,
> + function<void(AbstractAccount *)>);
> +};
> +struct AbstractTimelineModel {
> + AbstractAccount m_account;
> +};
> +struct LinkPaginationTimelineModel : AbstractTimelineModel {
> + void fillTimeline();
> +};
> +void LinkPaginationTimelineModel::fillTimeline() {
> + [] {};
> + m_account.get([](AbstractAccount *) { static QRegularExpression re(""); },
> + [](AbstractAccount *) {});
> +}
> diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C b/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C
> index 291e451ca1a..a7cb6c5dece 100644
> --- a/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C
> +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C
> @@ -1,4 +1,5 @@
> // { dg-do run { target c++20 } }
> +// { dg-additional-options "-flto" { target lto } } (PR107897)
>
> template<typename T>
> concept C1 = __is_same_as(T, int)
>
> base-commit: 4f181f9c7ee3efc509d185fdfda33be9018f1611
> --
> 2.31.1
>
On 3/8/23 10:53, Jan Hubicka wrote:
>> Tested x86_64-pc-linux-gnu. Does this look good, or do we want to factor the
>> flag clearing into a symtab_node counterpart to cgraph_node::reset?
>>
>> -- 8< --
>>
>> In 107897, by the time we are looking at the mangling clash, the
>> alias has already been removed from the symbol table by analyze_functions,
>> so we can't look at n->cpp_implicit_alias. So just assume that it's an
>> alias if it's internal.
>>
>> In 108887 the problem is that removing the mangling alias from the symbol
>> table confuses analyze_functions, because it ended up as first_analyzed
>> somehow, so it becomes a dangling pointer. Fixed by clearing various flags
>> to neutralize the alias.
>>
>> PR c++/107897
>> PR c++/108887
>>
>> gcc/cp/ChangeLog:
>>
>> * decl2.cc (record_mangling): Improve symbol table handling.
>>
>> gcc/testsuite/ChangeLog:
>>
>> * g++.dg/cpp2a/concepts-lambda3.C: Use -flto if supported.
>> * g++.dg/cpp0x/lambda/lambda-mangle7.C: New test.
>> ---
>> gcc/cp/decl2.cc | 25 +++++--
>> .../g++.dg/cpp0x/lambda/lambda-mangle7.C | 70 +++++++++++++++++++
>> gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C | 1 +
>> 3 files changed, 91 insertions(+), 5 deletions(-)
>> create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C
>>
>> diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
>> index 387e24542cd..e6e58b08de4 100644
>> --- a/gcc/cp/decl2.cc
>> +++ b/gcc/cp/decl2.cc
>> @@ -4742,15 +4742,30 @@ record_mangling (tree decl, bool need_warning)
>> = mangled_decls->find_slot_with_hash (id, IDENTIFIER_HASH_VALUE (id),
>> INSERT);
>>
>> - /* If this is already an alias, remove the alias, because the real
>> + /* If this is already an alias, cancel the alias, because the real
>> decl takes precedence. */
>> if (*slot && DECL_ARTIFICIAL (*slot) && DECL_IGNORED_P (*slot))
>> - if (symtab_node *n = symtab_node::get (*slot))
>> - if (n->cpp_implicit_alias)
>> + {
>> + if (symtab_node *n = symtab_node::get (*slot))
>> {
>> - n->remove ();
>> - *slot = NULL_TREE;
>> + if (n->cpp_implicit_alias)
>> + {
>> + /* Actually removing the node isn't safe if other code is already
>> + holding a pointer to it, so just neutralize it. */
>> + n->remove_from_same_comdat_group ();
>> + n->analyzed = false;
>> + n->definition = false;
>> + n->alias = false;
>> + n->cpp_implicit_alias = false;
> We have n->reset () for that which is used in similar situation when
> frontends overwrites extern inline function by its different offline
> implementation.
The problem there is that reset() is a member of cgraph_node, not
symtab_node, and I need something that works for variables as well.
> reset doesn't call remove_from_same_comdat_group probably because it was
> never used on anything in comdat group. So I think it would make sense
> to call n->reset() here and add remove_from_same_comdat_group into that.
>
> OK with that change.
> Honza
>> + }
>> }
>> + else
>> + /* analyze_functions might have already removed the alias from the
>> + symbol table if it's internal. */
>> + gcc_checking_assert (!TREE_PUBLIC (*slot));
>> +
>> + *slot = NULL_TREE;
>> + }
>>
>> if (!*slot)
>> *slot = decl;
>> diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C
>> new file mode 100644
>> index 00000000000..c7946a2be08
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C
>> @@ -0,0 +1,70 @@
>> +// PR c++/108887
>> +// { dg-do compile { target c++11 } }
>> +
>> +template <int __v> struct integral_constant {
>> + static constexpr int value = __v;
>> +};
>> +using false_type = integral_constant<false>;
>> +template <bool, bool, typename...> struct __result_of_impl;
>> +template <typename _Functor, typename... _ArgTypes>
>> +struct __result_of_impl<false, false, _Functor, _ArgTypes...> {
>> + typedef decltype(0) type;
>> +};
>> +template <typename... _ArgTypes>
>> +struct __invoke_result
>> + : __result_of_impl<false_type::value, false_type::value, _ArgTypes...> {};
>> +template <typename, typename _Fn, typename... _Args>
>> +void __invoke_impl(_Fn __f, _Args... __args) {
>> + __f(__args...);
>> +}
>> +template <typename, typename _Callable, typename... _Args>
>> +void __invoke_r(_Callable __fn, _Args... __args) {
>> + using __result = __invoke_result<_Args...>;
>> + using __type = typename __result::type;
>> + __invoke_impl<__type>(__fn, __args...);
>> +}
>> +struct QString {
>> + QString(const char *);
>> +};
>> +template <typename> class function;
>> +template <typename _Functor> struct _Base_manager {
>> + static _Functor _M_get_pointer(int) { __builtin_abort (); }
>> +};
>> +template <typename, typename> class _Function_handler;
>> +template <typename _Res, typename _Functor, typename... _ArgTypes>
>> +struct _Function_handler<_Res(_ArgTypes...), _Functor> {
>> + using _Base = _Base_manager<_Functor>;
>> + static _Res _M_invoke(const int &__functor, _ArgTypes &&...__args) {
>> + auto __trans_tmp_1 = _Base::_M_get_pointer(__functor);
>> + __invoke_r<_Res>(__trans_tmp_1, __args...);
>> + }
>> +};
>> +template <typename _Res, typename... _ArgTypes>
>> +struct function<_Res(_ArgTypes...)> {
>> + template <typename _Functor>
>> + using _Handler = _Function_handler<_Res(_ArgTypes...), _Functor>;
>> + template <typename _Functor> function(_Functor) {
>> + using _My_handler = _Handler<_Functor>;
>> + _M_invoker = _My_handler::_M_invoke;
>> + }
>> + using _Invoker_type = _Res (*)(const int &, _ArgTypes &&...);
>> + _Invoker_type _M_invoker;
>> +};
>> +struct QRegularExpression {
>> + QRegularExpression(QString);
>> +};
>> +struct AbstractAccount {
>> + void get(function<void(AbstractAccount *)>,
>> + function<void(AbstractAccount *)>);
>> +};
>> +struct AbstractTimelineModel {
>> + AbstractAccount m_account;
>> +};
>> +struct LinkPaginationTimelineModel : AbstractTimelineModel {
>> + void fillTimeline();
>> +};
>> +void LinkPaginationTimelineModel::fillTimeline() {
>> + [] {};
>> + m_account.get([](AbstractAccount *) { static QRegularExpression re(""); },
>> + [](AbstractAccount *) {});
>> +}
>> diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C b/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C
>> index 291e451ca1a..a7cb6c5dece 100644
>> --- a/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C
>> +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C
>> @@ -1,4 +1,5 @@
>> // { dg-do run { target c++20 } }
>> +// { dg-additional-options "-flto" { target lto } } (PR107897)
>>
>> template<typename T>
>> concept C1 = __is_same_as(T, int)
>>
>> base-commit: 4f181f9c7ee3efc509d185fdfda33be9018f1611
>> --
>> 2.31.1
>>
>
On 3/8/23 11:15, Jason Merrill wrote:
> On 3/8/23 10:53, Jan Hubicka wrote:
>>> Tested x86_64-pc-linux-gnu. Does this look good, or do we want to
>>> factor the
>>> flag clearing into a symtab_node counterpart to cgraph_node::reset?
>>>
>>> -- 8< --
>>>
>>> In 107897, by the time we are looking at the mangling clash, the
>>> alias has already been removed from the symbol table by
>>> analyze_functions,
>>> so we can't look at n->cpp_implicit_alias. So just assume that it's an
>>> alias if it's internal.
>>>
>>> In 108887 the problem is that removing the mangling alias from the
>>> symbol
>>> table confuses analyze_functions, because it ended up as first_analyzed
>>> somehow, so it becomes a dangling pointer. Fixed by clearing various
>>> flags
>>> to neutralize the alias.
>>>
>>> PR c++/107897
>>> PR c++/108887
>>>
>>> gcc/cp/ChangeLog:
>>>
>>> * decl2.cc (record_mangling): Improve symbol table handling.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> * g++.dg/cpp2a/concepts-lambda3.C: Use -flto if supported.
>>> * g++.dg/cpp0x/lambda/lambda-mangle7.C: New test.
>>> ---
>>> gcc/cp/decl2.cc | 25 +++++--
>>> .../g++.dg/cpp0x/lambda/lambda-mangle7.C | 70 +++++++++++++++++++
>>> gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C | 1 +
>>> 3 files changed, 91 insertions(+), 5 deletions(-)
>>> create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C
>>>
>>> diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
>>> index 387e24542cd..e6e58b08de4 100644
>>> --- a/gcc/cp/decl2.cc
>>> +++ b/gcc/cp/decl2.cc
>>> @@ -4742,15 +4742,30 @@ record_mangling (tree decl, bool need_warning)
>>> = mangled_decls->find_slot_with_hash (id, IDENTIFIER_HASH_VALUE
>>> (id),
>>> INSERT);
>>> - /* If this is already an alias, remove the alias, because the real
>>> + /* If this is already an alias, cancel the alias, because the real
>>> decl takes precedence. */
>>> if (*slot && DECL_ARTIFICIAL (*slot) && DECL_IGNORED_P (*slot))
>>> - if (symtab_node *n = symtab_node::get (*slot))
>>> - if (n->cpp_implicit_alias)
>>> + {
>>> + if (symtab_node *n = symtab_node::get (*slot))
>>> {
>>> - n->remove ();
>>> - *slot = NULL_TREE;
>>> + if (n->cpp_implicit_alias)
>>> + {
>>> + /* Actually removing the node isn't safe if other code is
>>> already
>>> + holding a pointer to it, so just neutralize it. */
>>> + n->remove_from_same_comdat_group ();
>>> + n->analyzed = false;
>>> + n->definition = false;
>>> + n->alias = false;
>>> + n->cpp_implicit_alias = false;
>> We have n->reset () for that which is used in similar situation when
>> frontends overwrites extern inline function by its different offline
>> implementation.
>
> The problem there is that reset() is a member of cgraph_node, not
> symtab_node, and I need something that works for variables as well.
>
>> reset doesn't call remove_from_same_comdat_group probably because it was
>> never used on anything in comdat group. So I think it would make sense
>> to call n->reset() here and add remove_from_same_comdat_group into that.
How about moving it to symtab_node and using dyn_cast for the cgraph
bits, like this:
On 3/8/23 11:54, Jason Merrill wrote:
> On 3/8/23 11:15, Jason Merrill wrote:
>> On 3/8/23 10:53, Jan Hubicka wrote:
>>>> Tested x86_64-pc-linux-gnu. Does this look good, or do we want to
>>>> factor the
>>>> flag clearing into a symtab_node counterpart to cgraph_node::reset?
>>>>
>>>> -- 8< --
>>>>
>>>> In 107897, by the time we are looking at the mangling clash, the
>>>> alias has already been removed from the symbol table by
>>>> analyze_functions,
>>>> so we can't look at n->cpp_implicit_alias. So just assume that it's an
>>>> alias if it's internal.
>>>>
>>>> In 108887 the problem is that removing the mangling alias from the
>>>> symbol
>>>> table confuses analyze_functions, because it ended up as first_analyzed
>>>> somehow, so it becomes a dangling pointer. Fixed by clearing
>>>> various flags
>>>> to neutralize the alias.
>>>>
>>>> PR c++/107897
>>>> PR c++/108887
>>>>
>>>> gcc/cp/ChangeLog:
>>>>
>>>> * decl2.cc (record_mangling): Improve symbol table handling.
>>>>
>>>> gcc/testsuite/ChangeLog:
>>>>
>>>> * g++.dg/cpp2a/concepts-lambda3.C: Use -flto if supported.
>>>> * g++.dg/cpp0x/lambda/lambda-mangle7.C: New test.
>>>> ---
>>>> gcc/cp/decl2.cc | 25 +++++--
>>>> .../g++.dg/cpp0x/lambda/lambda-mangle7.C | 70
>>>> +++++++++++++++++++
>>>> gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C | 1 +
>>>> 3 files changed, 91 insertions(+), 5 deletions(-)
>>>> create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C
>>>>
>>>> diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
>>>> index 387e24542cd..e6e58b08de4 100644
>>>> --- a/gcc/cp/decl2.cc
>>>> +++ b/gcc/cp/decl2.cc
>>>> @@ -4742,15 +4742,30 @@ record_mangling (tree decl, bool need_warning)
>>>> = mangled_decls->find_slot_with_hash (id,
>>>> IDENTIFIER_HASH_VALUE (id),
>>>> INSERT);
>>>> - /* If this is already an alias, remove the alias, because the real
>>>> + /* If this is already an alias, cancel the alias, because the real
>>>> decl takes precedence. */
>>>> if (*slot && DECL_ARTIFICIAL (*slot) && DECL_IGNORED_P (*slot))
>>>> - if (symtab_node *n = symtab_node::get (*slot))
>>>> - if (n->cpp_implicit_alias)
>>>> + {
>>>> + if (symtab_node *n = symtab_node::get (*slot))
>>>> {
>>>> - n->remove ();
>>>> - *slot = NULL_TREE;
>>>> + if (n->cpp_implicit_alias)
>>>> + {
>>>> + /* Actually removing the node isn't safe if other code is
>>>> already
>>>> + holding a pointer to it, so just neutralize it. */
>>>> + n->remove_from_same_comdat_group ();
>>>> + n->analyzed = false;
>>>> + n->definition = false;
>>>> + n->alias = false;
>>>> + n->cpp_implicit_alias = false;
>>> We have n->reset () for that which is used in similar situation when
>>> frontends overwrites extern inline function by its different offline
>>> implementation.
>>
>> The problem there is that reset() is a member of cgraph_node, not
>> symtab_node, and I need something that works for variables as well.
>>
>>> reset doesn't call remove_from_same_comdat_group probably because it was
>>> never used on anything in comdat group. So I think it would make sense
>>> to call n->reset() here and add remove_from_same_comdat_group into that.
>
> How about moving it to symtab_node and using dyn_cast for the cgraph
> bits, like this:
Ping? (Patch in attachment in earlier message)
On 3/14/23 11:16, Jason Merrill wrote:
> On 3/8/23 11:54, Jason Merrill wrote:
>> On 3/8/23 11:15, Jason Merrill wrote:
>>> On 3/8/23 10:53, Jan Hubicka wrote:
>>>>> Tested x86_64-pc-linux-gnu. Does this look good, or do we want to
>>>>> factor the
>>>>> flag clearing into a symtab_node counterpart to cgraph_node::reset?
>>>>>
>>>>> -- 8< --
>>>>>
>>>>> In 107897, by the time we are looking at the mangling clash, the
>>>>> alias has already been removed from the symbol table by
>>>>> analyze_functions,
>>>>> so we can't look at n->cpp_implicit_alias. So just assume that
>>>>> it's an
>>>>> alias if it's internal.
>>>>>
>>>>> In 108887 the problem is that removing the mangling alias from the
>>>>> symbol
>>>>> table confuses analyze_functions, because it ended up as
>>>>> first_analyzed
>>>>> somehow, so it becomes a dangling pointer. Fixed by clearing
>>>>> various flags
>>>>> to neutralize the alias.
>>>>>
>>>>> PR c++/107897
>>>>> PR c++/108887
>>>>>
>>>>> gcc/cp/ChangeLog:
>>>>>
>>>>> * decl2.cc (record_mangling): Improve symbol table handling.
>>>>>
>>>>> gcc/testsuite/ChangeLog:
>>>>>
>>>>> * g++.dg/cpp2a/concepts-lambda3.C: Use -flto if supported.
>>>>> * g++.dg/cpp0x/lambda/lambda-mangle7.C: New test.
>>>>> ---
>>>>> gcc/cp/decl2.cc | 25 +++++--
>>>>> .../g++.dg/cpp0x/lambda/lambda-mangle7.C | 70
>>>>> +++++++++++++++++++
>>>>> gcc/testsuite/g++.dg/cpp2a/concepts-lambda3.C | 1 +
>>>>> 3 files changed, 91 insertions(+), 5 deletions(-)
>>>>> create mode 100644
>>>>> gcc/testsuite/g++.dg/cpp0x/lambda/lambda-mangle7.C
>>>>>
>>>>> diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
>>>>> index 387e24542cd..e6e58b08de4 100644
>>>>> --- a/gcc/cp/decl2.cc
>>>>> +++ b/gcc/cp/decl2.cc
>>>>> @@ -4742,15 +4742,30 @@ record_mangling (tree decl, bool need_warning)
>>>>> = mangled_decls->find_slot_with_hash (id,
>>>>> IDENTIFIER_HASH_VALUE (id),
>>>>> INSERT);
>>>>> - /* If this is already an alias, remove the alias, because the real
>>>>> + /* If this is already an alias, cancel the alias, because the real
>>>>> decl takes precedence. */
>>>>> if (*slot && DECL_ARTIFICIAL (*slot) && DECL_IGNORED_P (*slot))
>>>>> - if (symtab_node *n = symtab_node::get (*slot))
>>>>> - if (n->cpp_implicit_alias)
>>>>> + {
>>>>> + if (symtab_node *n = symtab_node::get (*slot))
>>>>> {
>>>>> - n->remove ();
>>>>> - *slot = NULL_TREE;
>>>>> + if (n->cpp_implicit_alias)
>>>>> + {
>>>>> + /* Actually removing the node isn't safe if other code
>>>>> is already
>>>>> + holding a pointer to it, so just neutralize it. */
>>>>> + n->remove_from_same_comdat_group ();
>>>>> + n->analyzed = false;
>>>>> + n->definition = false;
>>>>> + n->alias = false;
>>>>> + n->cpp_implicit_alias = false;
>>>> We have n->reset () for that which is used in similar situation when
>>>> frontends overwrites extern inline function by its different offline
>>>> implementation.
>>>
>>> The problem there is that reset() is a member of cgraph_node, not
>>> symtab_node, and I need something that works for variables as well.
>>>
>>>> reset doesn't call remove_from_same_comdat_group probably because it
>>>> was
>>>> never used on anything in comdat group. So I think it would make sense
>>>> to call n->reset() here and add remove_from_same_comdat_group into
>>>> that.
>>
>> How about moving it to symtab_node and using dyn_cast for the cgraph
>> bits, like this:
>
> Ping? (Patch in attachment in earlier message)
>
Hello,
On Wed, Mar 08 2023, Jason Merrill via Gcc-patches wrote:
> On 3/8/23 11:15, Jason Merrill wrote:
>> On 3/8/23 10:53, Jan Hubicka wrote:
[...]
>>> We have n->reset () for that which is used in similar situation when
>>> frontends overwrites extern inline function by its different offline
>>> implementation.
>>
>> The problem there is that reset() is a member of cgraph_node, not
>> symtab_node, and I need something that works for variables as well.
>>
>>> reset doesn't call remove_from_same_comdat_group probably because it was
>>> never used on anything in comdat group. So I think it would make sense
>>> to call n->reset() here and add remove_from_same_comdat_group into that.
>
> How about moving it to symtab_node and using dyn_cast for the cgraph
> bits, like this:
> From 1d869ceb04573727e59be6518903133c8654069a Mon Sep 17 00:00:00 2001
> From: Jason Merrill <jason@redhat.com>
> Date: Mon, 6 Mar 2023 15:33:45 -0500
> Subject: [PATCH] c++: lambda mangling alias issues [PR107897]
> To: gcc-patches@gcc.gnu.org
>
> In 107897, by the time we are looking at the mangling clash, the
> alias has already been removed from the symbol table by analyze_functions,
> so we can't look at n->cpp_implicit_alias. So just assume that it's an
> alias if it's internal.
>
> In 108887 the problem is that removing the mangling alias from the symbol
> table confuses analyze_functions, because it ended up as first_analyzed
> somehow, so it becomes a dangling pointer. Fixed by clearing various flags
> to neutralize the alias.
>
> PR c++/107897
> PR c++/108887
>
> gcc/ChangeLog:
>
> * cgraph.h: Move reset() from cgraph_node to symtab_node.
> * cgraphunit.cc (symtab_node::reset): Adjust.
>
> gcc/cp/ChangeLog:
>
> * decl2.cc (record_mangling): Use symtab_node::reset.
The patch is OK.
Thanks,
Martin
>
> How about moving it to symtab_node and using dyn_cast for the cgraph bits,
> like this:
> From 1d869ceb04573727e59be6518903133c8654069a Mon Sep 17 00:00:00 2001
> From: Jason Merrill <jason@redhat.com>
> Date: Mon, 6 Mar 2023 15:33:45 -0500
> Subject: [PATCH] c++: lambda mangling alias issues [PR107897]
> To: gcc-patches@gcc.gnu.org
>
> In 107897, by the time we are looking at the mangling clash, the
> alias has already been removed from the symbol table by analyze_functions,
> so we can't look at n->cpp_implicit_alias. So just assume that it's an
> alias if it's internal.
>
> In 108887 the problem is that removing the mangling alias from the symbol
> table confuses analyze_functions, because it ended up as first_analyzed
> somehow, so it becomes a dangling pointer. Fixed by clearing various flags
> to neutralize the alias.
>
> PR c++/107897
> PR c++/108887
>
> gcc/ChangeLog:
>
> * cgraph.h: Move reset() from cgraph_node to symtab_node.
> * cgraphunit.cc (symtab_node::reset): Adjust.
>
> gcc/cp/ChangeLog:
>
> * decl2.cc (record_mangling): Use symtab_node::reset.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/cpp2a/concepts-lambda3.C: Use -flto if supported.
> * g++.dg/cpp0x/lambda/lambda-mangle7.C: New test.
OK and I apologize for the delay (my travels were more busy than I
hoped)
Honza
@@ -4742,15 +4742,30 @@ record_mangling (tree decl, bool need_warning)
= mangled_decls->find_slot_with_hash (id, IDENTIFIER_HASH_VALUE (id),
INSERT);
- /* If this is already an alias, remove the alias, because the real
+ /* If this is already an alias, cancel the alias, because the real
decl takes precedence. */
if (*slot && DECL_ARTIFICIAL (*slot) && DECL_IGNORED_P (*slot))
- if (symtab_node *n = symtab_node::get (*slot))
- if (n->cpp_implicit_alias)
+ {
+ if (symtab_node *n = symtab_node::get (*slot))
{
- n->remove ();
- *slot = NULL_TREE;
+ if (n->cpp_implicit_alias)
+ {
+ /* Actually removing the node isn't safe if other code is already
+ holding a pointer to it, so just neutralize it. */
+ n->remove_from_same_comdat_group ();
+ n->analyzed = false;
+ n->definition = false;
+ n->alias = false;
+ n->cpp_implicit_alias = false;
+ }
}
+ else
+ /* analyze_functions might have already removed the alias from the
+ symbol table if it's internal. */
+ gcc_checking_assert (!TREE_PUBLIC (*slot));
+
+ *slot = NULL_TREE;
+ }
if (!*slot)
*slot = decl;
new file mode 100644
@@ -0,0 +1,70 @@
+// PR c++/108887
+// { dg-do compile { target c++11 } }
+
+template <int __v> struct integral_constant {
+ static constexpr int value = __v;
+};
+using false_type = integral_constant<false>;
+template <bool, bool, typename...> struct __result_of_impl;
+template <typename _Functor, typename... _ArgTypes>
+struct __result_of_impl<false, false, _Functor, _ArgTypes...> {
+ typedef decltype(0) type;
+};
+template <typename... _ArgTypes>
+struct __invoke_result
+ : __result_of_impl<false_type::value, false_type::value, _ArgTypes...> {};
+template <typename, typename _Fn, typename... _Args>
+void __invoke_impl(_Fn __f, _Args... __args) {
+ __f(__args...);
+}
+template <typename, typename _Callable, typename... _Args>
+void __invoke_r(_Callable __fn, _Args... __args) {
+ using __result = __invoke_result<_Args...>;
+ using __type = typename __result::type;
+ __invoke_impl<__type>(__fn, __args...);
+}
+struct QString {
+ QString(const char *);
+};
+template <typename> class function;
+template <typename _Functor> struct _Base_manager {
+ static _Functor _M_get_pointer(int) { __builtin_abort (); }
+};
+template <typename, typename> class _Function_handler;
+template <typename _Res, typename _Functor, typename... _ArgTypes>
+struct _Function_handler<_Res(_ArgTypes...), _Functor> {
+ using _Base = _Base_manager<_Functor>;
+ static _Res _M_invoke(const int &__functor, _ArgTypes &&...__args) {
+ auto __trans_tmp_1 = _Base::_M_get_pointer(__functor);
+ __invoke_r<_Res>(__trans_tmp_1, __args...);
+ }
+};
+template <typename _Res, typename... _ArgTypes>
+struct function<_Res(_ArgTypes...)> {
+ template <typename _Functor>
+ using _Handler = _Function_handler<_Res(_ArgTypes...), _Functor>;
+ template <typename _Functor> function(_Functor) {
+ using _My_handler = _Handler<_Functor>;
+ _M_invoker = _My_handler::_M_invoke;
+ }
+ using _Invoker_type = _Res (*)(const int &, _ArgTypes &&...);
+ _Invoker_type _M_invoker;
+};
+struct QRegularExpression {
+ QRegularExpression(QString);
+};
+struct AbstractAccount {
+ void get(function<void(AbstractAccount *)>,
+ function<void(AbstractAccount *)>);
+};
+struct AbstractTimelineModel {
+ AbstractAccount m_account;
+};
+struct LinkPaginationTimelineModel : AbstractTimelineModel {
+ void fillTimeline();
+};
+void LinkPaginationTimelineModel::fillTimeline() {
+ [] {};
+ m_account.get([](AbstractAccount *) { static QRegularExpression re(""); },
+ [](AbstractAccount *) {});
+}
@@ -1,4 +1,5 @@
// { dg-do run { target c++20 } }
+// { dg-additional-options "-flto" { target lto } } (PR107897)
template<typename T>
concept C1 = __is_same_as(T, int)