参考
官方参数说明
索引
因为项目太大，线程太多，gprof不可靠，于是找到了finstrument-functions
-finstrument-functions 會在每次進入與退出函式前呼叫 "__cyg_profile_func_enter" 與 "__cyg_profile_func_exit" 這兩個 hook function。等等，「進入」與「退出」是又何解？C Programming Language 最經典之處在於，雖然沒有定義語言實做的方式，但實際上 function call 皆以 stack frame 的形式存在，去年在「深入淺出 Hello World」Part II 有提過。所以上述那一大段英文就是說，如果我們不透過 GCC 內建函式 "__builtin_return_address" 取得 caller 與 callee 相關的動態位址，那麼仍可透過 -finstrument-functions，讓 GCC 合成相關的處理指令，讓我們得以追蹤。而看到 __cyg 開頭的函式，就知道是來自 Cygnus 的貢獻，在 gcc 2.x 內部設計可瞥見不少。
c
hello.c
#include#define DUMP(func, call) printf("%s: func = %p, called by = %p/n", __FUNCTION__, func, call)void __attribute__((__no_instrument_function__))__cyg_profile_func_enter(void *this_func, void *call_site){ DUMP(this_func, call_site);}void __attribute__((__no_instrument_function__))__cyg_profile_func_exit(void *this_func, void *call_site){ DUMP(this_func, call_site);}main(){ puts("Hello World!"); return 0;}
makefile
all:hello.o gcc -finstrument-functions -finstrument-functions hello.o -o hellohello.o: gcc -finstrument-functions -c hello.cclean: rm *.o hello -rf
运行：
./hello__cyg_profile_func_enter: func = 0x8048438, called by = 0x658dec/nHello World!__cyg_profile_func_exit: func = 0x8048438, called by = 0x658dec/n
完
c++
hello.cc
#include#include #include #include #include using namespace std;#define DUMP(func, call) printf("%s: func = %p, called by = %p\n", __FUNCTION__, func, call)#ifdef __cplusplusextern "C" {#endif/* Static functions. */static FILE *openlogfile (const char *filename) __attribute__ ((no_instrument_function));static void closelogfile (void) __attribute__ ((no_instrument_function));/* Note that these are linked internally by the compiler. * Don't call them directly! */void __cyg_profile_func_enter (void *this_fn, void *call_site) __attribute__ ((no_instrument_function));void __cyg_profile_func_exit (void *this_fn, void *call_site) __attribute__ ((no_instrument_function));#ifdef __cplusplus};#endifvoid__cyg_profile_func_enter (void *this_fn, void *call_site){ DUMP(this_fn, call_site);}void__cyg_profile_func_exit (void *this_fn, void *call_site){ DUMP(this_fn, call_site);} intmain ( int argc, char *argv[] ){ cout << "\nProgram " << argv[0] << endl << endl; return EXIT_SUCCESS;} // ---------- end of function main ----------
makefile:
all: g++ -finstrument-functions hello.cc
运行：
./a.out__cyg_profile_func_enter: func = 0x80487ae, called by = 0x8048a3b__cyg_profile_func_enter: func = 0x8048714, called by = 0x80487d7__cyg_profile_func_exit: func = 0x8048714, called by = 0x80487d7__cyg_profile_func_exit: func = 0x80487ae, called by = 0x8048a3b__cyg_profile_func_enter: func = 0x8048882, called by = 0x658decProgram ./a.out__cyg_profile_func_exit: func = 0x8048882, called by = 0x658dec__cyg_profile_func_enter: func = 0x804881a, called by = 0x66e7f9__cyg_profile_func_exit: func = 0x804881a, called by = 0x66e7f9
hello.c
#include#include "test.h"#define DUMP(func, call) printf("%s: func = %p, called by = %p\n", __FUNCTION__, func, call)void __attribute__((__no_instrument_function__))__cyg_profile_func_enter(void *this_func, void *call_site){ DUMP(this_func, call_site);}void __attribute__((__no_instrument_function__))__cyg_profile_func_exit(void *this_func, void *call_site){ DUMP(this_func, call_site);}void test(){ printf("nihao\n");}main(){ test(); puts("Hello World!"); return 0;}
makefile
CC=gcc44all:hello.o $(CC) -g -finstrument-functions hello.o -o hellohello.o: $(CC) -g -finstrument-functions -finstrument-functions-exclude-function-list=test -c hello.cclean: rm *.o hello -rf
运行：
./hello__cyg_profile_func_enter: func = 0x804847e, called by = 0xb7e6adecnihaoHello World!__cyg_profile_func_exit: func = 0x804847e, called by = 0xb7e6adec
完