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嵌入代码

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chunli@blog:~/source/function_tree/gcc$ cat fun_tree.c
#define _GNU_SOURCE
#include <dlfcn.h>
#include <stdio.h>

int offset = 0;
FILE *report = NULL;

void __attribute__((__no_instrument_function__))
print_space(int n)
{
    int i = 0;
    for(i = 0; i < n; i++)
    {
        fprintf(report, " ");
    }
}

void __attribute__((__no_instrument_function__))
__cyg_profile_func_enter(void *this_func, void *call_site)
{
    print_space(offset);

    Dl_info info;
    if (dladdr(this_func, &info))
    {
        const char *sname  = info.dli_sname;
        fprintf(report, "+ %s\n", sname);
    }
    offset+=4;
}

void __attribute__((__no_instrument_function__))
__cyg_profile_func_exit(void *this_func, void *call_site)
{
    offset-=4;
    print_space(offset);
    Dl_info info;
    if (dladdr(this_func, &info))
    {
        const char *sname  = info.dli_sname;
        fprintf(report, "- %s\n", sname);
    }

}

void __attribute__((constructor)) __attribute__((__no_instrument_function__))
before_main()
{
    report = fopen("report.log", "w+");
}

void __attribute__((destructor)) __attribute__((__no_instrument_function__))
after_main()
{
    fclose(report);
}

// gcc -O0 -rdynamic -finstrument-functions  fun_tree.c xxx.c -ldl  && ./a.out
chunli@blog:~/source/function_tree/gcc$

业务代码

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chunli@blog:~/source/function_tree/gcc$ cat main.c

int fib(int n)
{
    if (n <= 0)    //基本情况
        return 0;
    else if (n == 1) // 基本情况
        return 1;
    else
        return fib(n - 1) + fib(n - 2);
}

int main()
{
    fib(5);
    return 0;
}

运行

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chunli@blog:~/source/function_tree/gcc$ gcc -O0 -rdynamic -finstrument-functions  main.c fun_tree.c -ldl  && ./a.out
chunli@blog:~/source/function_tree/gcc$ cat report.log
+ main
    + fib
        + fib
            + fib
                + fib
                    + fib
                    - fib
                    + fib
                    - fib
                - fib
                + fib
                - fib
            - fib
            + fib
                + fib
                - fib
                + fib
                - fib
            - fib
        - fib
        + fib
            + fib
                + fib
                - fib
                + fib
                - fib
            - fib
            + fib
            - fib
        - fib
    - fib
- main
chunli@blog:~/source/function_tree/gcc$