syscall无头输出

#pragma GCC optimize(1)
#pragma GCC optimize(2)
#pragma GCC optimize(3,"Ofast","inline")

extern "C" long syscall(long number, ...);

int main() {
    const char str[] = "Hello world";
    unsigned long len = sizeof(str) - 1;
    syscall(1, 1, str, len);
    return 0;
}

syscall内存消耗<cstdio内存消耗