带有 g++ -O2 ( 或 -Os, -O, -O1, ... ) 的模板警告

Question

我收到一些模板和 g++ -Os 的警告。为什么 ？如何使用 -Os -Winline 删除这些警告？

编辑1：G ++ v4.6.1如果我更换uint32_t的由无符号整型我的主要错误被纠正：（此bug已报道：http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52888）

Event.h:109:12: attention : inlining failed in call to ‘uint32_t Event<ParamT>::attach(ListenerT*, bool (ListenerT::*)(ParamT)) [with ListenerT = Listener, ParamT = unsigned int, uint32_t = unsigned int]’: mismatched arguments [-Winline]

编辑 2：以下警告似乎是 g++ 错误（http://gcc.gnu.org/ml/gcc-help/2012-07/msg00029.html）（我没有任何 ~Player() ）inlining failed in call to ‘Player::~Player()’: call is unlikely and code size would grow [-Winline]

编辑 3：要删除以前的警告，请添加Player::~Player() __attribute__ ((noinline)) {}

.

测试代码：Event.h

#ifndef EVENT_H
#define EVENT_H

#include <map>
#include <stdint.h>

/***************************************************************************//*!
* @brief Collect Listener
* @tparam ParamT        Param type of the function
*/
template<typename ParamT>
class EventHandlerBase
{
    public:
        virtual bool notify( ParamT param ) = 0;
};


/***************************************************************************//*!
* @brief Conteneur d'un receveur d'event.
* @tparam ListenerT     Object type
* @tparam ParamT        Param type of the function
*/
template<typename ListenerT, typename ParamT>
class EventHandler : public EventHandlerBase<ParamT>
{
    private:
        typedef bool (ListenerT::*PtrMember)(ParamT);

    private:
        ListenerT*      m_object;//!< Object listener
        PtrMember       m_member;//!< Function listener

    public:
        /********************************************************************//*!
        * @brief Constructor
        * @param[in] object     Instance listener
        * @param[in] member     Function listener ( Function need to be a public member of {object} )
        * @return[NONE]
        */
        EventHandler( ListenerT* object, PtrMember member )
        {
            m_object = object;
            m_member = member;
        }


        /*******************************************************************//*!
        * @brief Emit a signal to listeners
        * @param[in] param      Data
        * @return FALSE for breaking event loop
        */
        bool notify( ParamT param )
        {
            return (m_object->*m_member)(param);
        }
};


/***************************************************************************//*!
* @brief Event system
* @tparam ParamT        Param type of the function
*/
template<typename ParamT>
class Event
{
    private:
        typedef typename std::map< uint32_t, EventHandlerBase<ParamT>* > HandlersMap;

    private:
        HandlersMap     m_handlers;//!< Contient la liste des instances::fonctions en écoute sur cet event
        uint32_t        m_counter;//!< Permet de gérer les id

    public:
        /********************************************************************//*!
        * @brief Constructor
        * @return[NONE]
        */
        Event()
        {
            m_counter = 0;
        }


        /********************************************************************//*!
        * @brief Destructor
        * @return[NONE]
        */
        ~Event()
        {
            typename HandlersMap::iterator it = m_handlers.begin();
            for(; it != m_handlers.end(); it++)
            {
                if( it->second )
                    delete it->second;
            }
        }


        /*******************************************************************//*!
        * @brief Link a function and instance to this event
        * @param[in] object     Instance listener
        * @param[in] PtrMember  Function listener ( Function need to be a public member of {object} )
        * @return Connection ID
        *
        * @warning DO NOT FORGET TO CALL Event::detach(uint32_t) if you delete {object}
        */
        template<typename ListenerT>
        uint32_t attach( ListenerT* object, bool (ListenerT::*PtrMember)(ParamT) )
        {
            m_handlers[m_counter] = new EventHandler<ListenerT,ParamT>(object, PtrMember);
            m_counter++;
            return m_counter-1;
        }


        /*******************************************************************//*!
        * @brief Emit a signal to listeners
        * @param[in] param      Data
        * @return[NONE]
        */
        void notify( ParamT param )
        {
            typename HandlersMap::iterator it = m_handlers.begin();
            for(; it != m_handlers.end(); it++)
            {
                if( !it->second->notify(param) )
                    return ;
            }
        }


        /*******************************************************************//*!
        * @brief Unlink a listener.
        * @param[in] id     Connection ID from Event::attach
        * @return TRUE if removed
        */
        bool detach( uint32_t id )
        {
            typename HandlersMap::iterator it = m_handlers.find(id);

            if( it == m_handlers.end() )
                return false;

            delete it->second;
            m_handlers.erase(it);
            return true;
        }
};

#endif // EVENT_H

主程序

#include <stdio.h>
#include "Event.h"

class Player
{
    public:
        Event<uint32_t> e_speed;

    private:
        uint32_t        m_speed;

    public:
        Player()
        {
            m_speed = 15;
        }
        void setSpeed( uint32_t speed )
        {
            m_speed = speed;
            e_speed.notify(speed);
        }
};

class Listener
{
    private:
        Player      m_player;

    public:
        Listener()
        {
            m_player.e_speed.attach(this, &Listener::SLOT_speed);
        }
        bool SLOT_speed( uint32_t speed )
        {
            printf("Speed changed to %u\n", speed);
            return true;
        }
        Player* player()
        {
            return &m_player;
        }
};

int main()
{
    Listener l;
    l.player()->setSpeed(42);

    return 0;
}

使用以下命令编译此代码：g++ -Os -W -Wall -Winline *.cpp 您将收到以下警告：

Event.h:109:12: attention : inlining failed in call to ‘uint32_t Event<ParamT>::attach(ListenerT*, bool (ListenerT::*)(ParamT)) [with ListenerT = Listener, ParamT = unsigned int, uint32_t = unsigned int]’: mismatched arguments [-Winline]
main.cpp:32:56: attention : appelé d'ici [-Winline]
main.cpp:4:7: attention : inlining failed in call to ‘Player::~Player()’: call is unlikely and code size would grow [-Winline]
main.cpp:31:3: attention : appelé d'ici [-Winline]
main.cpp:4:7: attention : inlining failed in call to ‘Player::~Player()’: call is unlikely and code size would grow [-Winline]
main.cpp:24:7: attention : appelé d'ici [-Winline]
main.cpp:4:7: attention : inlining failed in call to ‘Player::~Player()’: call is unlikely and code size would grow [-Winline]
main.cpp:24:7: attention : appelé d'ici [-Winline]

Answer 1

你的动机有点不清楚......

您希望警告消失吗？删除-Winline选项。这就是它的作用：它警告非内联内联函数。

即使代码可能变大/变慢，您是否希望内联这些函数？您将不得不使用启发式进行内联。您可以尝试多种选择：

• 添加__attribute__(always_inline)相关功能。
• 与编译-finline-limit=N一个大N。
• 使用编译器选项--param NAME=VALUE。有几十参数控制内联（max-inline-insns-single，max-inline-insns-auto，large-function-insns，inline-unit-growth，等），你可以阅读info gcc，以获得详细信息。