stub function will not be called when two nested functions in the same file

[dsocer]

In the following example, test_stub will not be called. But test_stub will be call when fun1 and fun2 are in two diff files.

main.c:
int test_stub(int a){
return 0;
}
stub.set(fun1, test_stub);
fun2(1);

test.c:
fun1(int a){return a;}
fun2(int a){ return fun1(a);}

[coolxv]

What are the compile options？

[dsocer]

cmake
SET(CMAKE_DXX_FLAGS_DEFAULT "-O2")
SET(CMAKE_CXX_FLAGS_RELEASE "-O2")
SET(CMAKE_CXX_FLAGS_DEBUG "-O0 -g")

[coolxv]

It's optimized by the compiler.

main.cpp

#include"stub.h"
#include <iostream>

int fun1(int a);
int fun2(int a);

int test_stub(int a){
    std::cout << "test_stub" << std::endl;
    return 0;
}

int main(){
    Stub stub;
    stub.set(fun1, test_stub);
    fun2(1);
    return 0;
}

test.cpp

int fun1(int a){return a;}
int fun2(int a){ return fun1(a);}

• g++ -O2 test.cpp main.cpp -o main
  objdump -d main | c++filt

00000000000015f0 <fun2(int)>:
    15f0:       f3 0f 1e fa             endbr64
    15f4:       89 f8                   mov    %edi,%eax
    15f6:       c3                      retq
    15f7:       66 0f 1f 84 00 00 00    nopw   0x0(%rax,%rax,1)
    15fe:       00 00

• g++ test.cpp main.cpp -o main
  objdump -d main | c++filt

00000000000013d9 <fun2(int)>:
    13d9:       f3 0f 1e fa             endbr64
    13dd:       55                      push   %rbp
    13de:       48 89 e5                mov    %rsp,%rbp
    13e1:       48 83 ec 08             sub    $0x8,%rsp
    13e5:       89 7d fc                mov    %edi,-0x4(%rbp)
    13e8:       8b 45 fc                mov    -0x4(%rbp),%eax
    13eb:       89 c7                   mov    %eax,%edi
    13ed:       e8 d7 ff ff ff          callq  13c9 <fun1(int)>
    13f2:       c9                      leaveq
    13f3:       c3                      retq

[dsocer]

Thank for your answer. However, I still have the same issue with -O0. My functions are much more complex than the ones in the above example so the compiler cannot remove fun1.

[coolxv]

Give me an example of a problem so I can analyze it.

[dsocer]

I think the above example can show the issue. With the command: "g++ test.cpp main.cpp -o main" and "./main" has a seg fault.

But if I separate the two functions in different files test1.cpp and test2.cpp, then it works well.

test1.cpp
int fun1(int a){return a;}

test2.cpp
int fun1(int a);
int fun2(int a){ return fun1(a);}