Visual Studio 断点被移动

Question

我最初使用 Visual Studio C++ Express，我已切换到 Ultimate，目前我对调试器为何移动我的断点感到困惑，例如：

if(x > y) {
    int z = x/y;         < --- breakpoint set here
}
int h = x+y;             < --- breakpoint is moved here during run time

或者

random line of code      < --- breakpoint set here
random line of code

return someValue;        < --- breakpoint is moved here during run time

它似乎在代码中的随机位置执行此操作。有时我在这里做错了吗？我在使用 Express 版本时从未遇到过这样的问题。

Answer 1

您正在发布模式下进行调试。

if(x > y) {
    //this statement does nothing
    //z is a local variable that's never used
    //no executable code is generated for this line
    int z = x/y;         < --- breakpoint set here
}
//the breakpoint is set on the next executable line
//which happens to be this one
int h = x+y;             < --- breakpoint is moved here during run time

通常调试器在二进制代码中设置挂钩。如果没有对 int z = x/y 执行二进制代码，则无法在那里设置断点。

以下是通过在发布模式下编译生成的：

if(x > y) 
{
    int z = x/y;//         < --- breakpoint set here
}
int h = x+y;
cout << h;
003B1000  mov         ecx,dword ptr [__imp_std::cout (3B203Ch)] 
003B1006  push        7    
003B1008  call        dword ptr [__imp_std::basic_ostream<char,std::char_traits<char> >::operator<< (3B2038h)]

要测试它，您可以执行以下简单的更改：

if(x > y) {
    int z = x/y;
    std::cout << z << endl; // <-- set breakpoint here, this should work
}
int h = x+y;