Using gcc/g++ instrument functions with MinGW? - c++

Question

i try to use the gcc instrument functions with g++ compiler of MinGW, but i
always got linker issues. Is it possible to use the instrument functions with
MinGW/MSYS?
The linker failure output:
$ g++ instrumentFunctions.cpp -o iftest -finstrument-functions >> iflog.txt
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x4e): undefined reference to `__cyg_prof
ile_func_enter'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x158): undefined reference to `__cyg_pro
file_func_exit'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x179): undefined reference to `__cyg_pro
file_func_enter'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x18c): undefined reference to `__cyg_pro
file_func_exit'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x1a7): undefined reference to `__cyg_pro
file_func_enter'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x1bf): undefined reference to `__cyg_pro
file_func_exit'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x1db): undefined reference to `__cyg_pro
file_func_enter'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x1f3): undefined reference to `__cyg_pro
file_func_exit'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x22f): undefined reference to `__cyg_pro
file_func_enter'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x27a): undefined reference to `__cyg_pro
file_func_exit'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x29b): undefined reference to `__cyg_pro
file_func_enter'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x2e4): undefined reference to `__cyg_pro
file_func_exit'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x2ff): undefined reference to `__cyg_pro
file_func_enter'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x326): undefined reference to `__cyg_pro
file_func_exit'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x341): undefined reference to `__cyg_pro
file_func_enter'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text+0x368): undefined reference to `__cyg_pro
file_func_exit'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text$printf[_printf]+0x16): undefined referenc
e to `__cyg_profile_func_enter'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text$printf[_printf]+0x43): undefined referenc
e to `__cyg_profile_func_exit'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text$_ZSt3minIjERKT_S2_S2_[unsigned int const&
std::min<unsigned int>(unsigned int const&, unsigned int const&)]+0x15): undefined reference to `__cyg_profile_func_ent
er'
C:/Users/HELLHO~1/AppData/Local/Temp/ccUwxrxt.o:instrumentFunctions.cpp:(.text$_ZSt3minIjERKT_S2_S2_[unsigned int const&
std::min<unsigned int>(unsigned int const&, unsigned int const&)]+0x42): undefined reference to `__cyg_profile_func_exi
t'
collect2: ld returned 1 exit status
g++ command i use:
g++ iftest.cpp -o iftest -finstruction-functions
Listing of my testsource:
#include <stdio.h>
void __cyg_profile_func_enter( void *, void * ) __attribute__ ((no_instrument_function));
void __cyg_profile_func_enter(void *func, void *callsite)
{
printf("%p\n", (int)func);
}
void func_c( void )
{
return;
}
void func_b( void )
{
func_c();
return;
}
void func_a( void )
{
func_b();
return;
}
int main()
{
func_a();
func_c();
}

Answer 1

You need to give the __cyg* functions "C" linkage. A function defined in C++ normally gets a mangled name which can't be used from libraries not written in C++. You can ask the compiler to give a function the name C would give it by using an `extern "C"{} block. The following should compile fine.
#include <stdio.h>
extern "C" {
void __cyg_profile_func_enter( void *, void * ) __attribute__ ((no_instrument_function));
void __cyg_profile_func_enter(void *func, void *callsite)
{
printf("enter %p\n", func);
}
void __cyg_profile_func_exit( void *, void * ) __attribute__ ((no_instrument_function));
void __cyg_profile_func_exit(void *func, void *callsite)
{
printf("exit %p\n", func);
}
}
void func_c( void )
{
return;
}
void func_b( void )
{
func_c();
return;
}
void func_a( void )
{
func_b();
return;
}
int main()
{
func_a();
func_c();
}