GNU gdb无法进入模板功能(OS X Mavericks)

Question

我gdb 7.7在OS X Mavericks(10.9.2)下安装了(来自GNU源代码).我对它进行了编码,因此每当我调试c++不包含模板的文件时它都能正常工作.但是,它无法进入模板函数(可以进入常规函数,但只是无法进入模板函数).当我step在调试会话中键入命令时,它只是跳过该函数,就好像模板函数没有调试符号一样.我的模板函数甚至不是成员函数,只是里面定义的一个简单函数main.cpp.

我编译我的程序用g++ -g -O0 main.cpp(我用g++4.8.2的macports,而不是clang++),甚至试图-fno-inline,还是同样的行为,无法步入模板函数.这是gdbOS X Mavericks下的已知问题吗？或者,任何人都可以重现这个错误吗？

我的代码:

#include <iostream>

template <typename T> // template
void f(T x)
{
    std::cout << "In f:" << std::endl;
    std::cout << x << std::endl;
}

void g() // non-template
{
    std::cout << "It works here!" << std::endl;
    std::cout << "Exiting g()..." << std::endl;
}

int main() 
{
    f<double>(12.3); // gdb does not step into f()
    g(); // gdb steps into g()
}

在f断点之后无法介入f<double>(12.3).如果f()是常规函数,例如g()在我的代码中,则它会进入.谢谢!

更新:gdb在任何其他操作系统下工作,例如linux/windows/solaris.这似乎是与OS X相关的问题.

Reading symbols from a.out...done.
(gdb) disassemble main
Dump of assembler code for function main():
   0x0000000100000d62 <+0>: push   %rbp
   0x0000000100000d63 <+1>: mov    %rsp,%rbp
   0x0000000100000d66 <+4>: movabs $0x402899999999999a,%rax
   0x0000000100000d70 <+14>:    movq   %rax,%xmm0
   0x0000000100000d75 <+19>:    callq  0x100000e44
   0x0000000100000d7a <+24>:    callq  0x100000d0c <g()>
   0x0000000100000d7f <+29>:    mov    $0x0,%eax
   0x0000000100000d84 <+34>:    pop    %rbp
   0x0000000100000d85 <+35>:    retq
End of assembler dump.
(gdb)

现在我们在入口处设置一个断点 main()

(gdb) b main
Breakpoint 1 at 0x100000d66: file src/templated_bug.cpp, line 22.
(gdb) r
Starting program: /Users/vlad/template_gdb_bug/a.out

Breakpoint 1, main () at src/templated_bug.cpp:22
22      f<double>(12.3);
(gdb) s
In f:
12.3
23      g();
(gdb) s
g () at src/templated_bug.cpp:16
16      cout<<"It works here!"<<endl;
(gdb) s
It works here!
17      cout<<"Exiting g()..."<<endl;
(gdb) s
Exiting g()...
18  }
(gdb) s
main () at src/templated_bug.cpp:24
24  }
(gdb) s
[Inferior 1 (process 50945) exited normally]
(gdb)

正如你所看到的,它并没有进入内部,f()而是进入内部g().此外,

(gdb) disassemble f
No symbol "f" in current context.

但是,对于g()非模板的另一个函数,符号被加载,我可以反汇编它.

(gdb) disassemble g
Dump of assembler code for function g():
   0x0000000100000d0c <+0>: push   %rbp
   0x0000000100000d0d <+1>: mov    %rsp,%rbp
   0x0000000100000d10 <+4>: lea    0x193(%rip),%rsi        # 0x100000eaa
   0x0000000100000d17 <+11>:    mov    0x2ea(%rip),%rax        # 0x100001008
   0x0000000100000d1e <+18>:    mov    %rax,%rdi
   0x0000000100000d21 <+21>:    callq  0x100000e5c
   0x0000000100000d26 <+26>:    mov    0x2e3(%rip),%rdx        # 0x100001010
   0x0000000100000d2d <+33>:    mov    %rdx,%rsi
   0x0000000100000d30 <+36>:    mov    %rax,%rdi
   0x0000000100000d33 <+39>:    callq  0x100000e4a
   0x0000000100000d38 <+44>:    lea    0x17a(%rip),%rsi        # 0x100000eb9
   0x0000000100000d3f <+51>:    mov    0x2c2(%rip),%rax        # 0x100001008
   0x0000000100000d46 <+58>:    mov    %rax,%rdi
   0x0000000100000d49 <+61>:    callq  0x100000e5c
   0x0000000100000d4e <+66>:    mov    0x2bb(%rip),%rdx        # 0x100001010
   0x0000000100000d55 <+73>:    mov    %rdx,%rsi
   0x0000000100000d58 <+76>:    mov    %rax,%rdi
   0x0000000100000d5b <+79>:    callq  0x100000e4a
   0x0000000100000d60 <+84>:    pop    %rbp
   0x0000000100000d61 <+85>:    retq
End of assembler dump.

Answer 1

在 gdb 的 MacOS 端口上执行命令似乎存在问题。作为解决方法，您可以在函数开始处设置断点以单步执行模板函数：

(gdb) b f<double>
Breakpoint 1 at 0x1000015ab: file ./gdb_tmpl.cpp, line 6.
(gdb) run
Starting program: /Users/vershov/tmp/tests/a.out 

Breakpoint 1, f<double> (x=12.300000000000001) at ./gdb_tmpl.cpp:6
6       std::cout << "In f:" << std::endl;

另外，你可以反汇编它，只需使用正确的命令：

(gdb) disass f
No symbol "f" in current context.
(gdb) disass f<double>
Dump of assembler code for function f<double>(double):
   0x0000000100001590 <+0>: push   %rbp
   0x0000000100001591 <+1>: mov    %rsp,%rbp
   0x0000000100001594 <+4>: sub    $0x40,%rsp
   0x0000000100001598 <+8>: mov    0xa71(%rip),%rdi        # 0x100002010
   0x000000010000159f <+15>:    lea    0x9a0(%rip),%rsi        # 0x100001f46
...