/* ------------------------------------------------------------- *//* function to get a stack backtrace on demand with a message */ #include <stdarg.h>#include <stdio.h>#include <string.h> int (*__rt_error)(void*, void*, const char *, va_list); #ifdef _WIN32# define DLL_EXPORT __declspec(dllexport)#else# define DLL_EXPORT#endif DLL_EXPORT int tcc_backtrace(const char *fmt, ...){    va_list ap;    int ret;     if (__rt_error) {        void *fp = __builtin_frame_address(1);        void *ip = __builtin_return_address(0);        va_start(ap, fmt);        ret = __rt_error(fp, ip, fmt, ap);        va_end(ap);    } else {        const char *p;        if (fmt[0] == '^' && (p = strchr(fmt + 1, fmt[0])))            fmt = p + 1;        va_start(ap, fmt);        ret = vfprintf(stderr, fmt, ap);        va_end(ap);        fprintf(stderr, "\n"), fflush(stderr);    }    return ret;}