c++ - 反汇编程序 GLOBAL 关键字

Question

在 C++ 程序的反汇编 View 中，引用 GLOBAL 的内容？我有一个 lign 说:

je 0xb74d334a <_GLOBAL__sub_I_myFile.cpp+106>

我猜这是对 myFile.cpp 的调用，但我想知道调用前 GLOBAL 字的含义 ...

myFile.cpp 的内容:

[include guards]
#include <mutex.hpp> // Functions I use to handle mutex
namespce myNameSpace {
    class myClass {
        public:
            static void stdOutFormat(const char* format, ...);
        private:
            static Mutex(Synchro) // Custom functions from mutex.hpp and others ...
    };
}
[end include guards]

反汇编(我尽量简洁):

[some calls]
call 0xb74d1b80 <os_mutexInit@plt>
test %esi, %esi
je   0xb74d33a <_GLOBAL__sub_I_myFile.cpp+106>
mov  (%esi), %eax
[some calls]

Answer 1

此类符号用于编译器生成的静态初始值设定项。来自GCJ mailing list :

Symbols of the _GLOBAL__I__XXX are used for static initializers - i.e. code that executed on startup, normally before main is called. Don't get hung up on the actual XXX - it is just a magic mangling to create a unique symbol. Gcj creates static initializer functions that call _Jv_RegisterClass to register each class in a global table, so future Class.forName can find them.

这里讨论的是 GCJ，但 C++ 编译器的行为方式类似。指向所有此类初始化器的指针都放入 .ctors 部分，并在调用 main() 之前由 CRT 启动代码调用。