c++ - g++ 内联调用 always_inline "int _rdrand16_step()"失败

Question

我使用英特尔函数 _rdrand16_step() 编写了一段代码，在 Windows(Visual Studio 2017)上运行良好，但在 Linux(g++)上我无法使其运行。 我在我的代码中调用了该函数 2 次:

#include <immintrin.h>
...
unsigned short val = 0;
if (_rdrand16_step(&val))
...
_rdrand16_step(&val);
...

g++ 输出如下:

/usr/lib/gcc/x86_64-linux-gnu/8/include/immintrin.h: In member function ‘int otp_s7c::crypt(std::__cxx11::string, std::__cxx11::string, long long unsigned int)’:
/usr/lib/gcc/x86_64-linux-gnu/8/include/immintrin.h:129:1: error: inlining failed in call to always_inline ‘int _rdrand16_step(short unsigned int*)’: target specific option mismatch
 _rdrand16_step (unsigned short *__P)
 ^~~~~~~~~~~~~~
otp_s7c.cpp:139:24: note: called from here
      if (_rdrand16_step(&val))
          ~~~~~~~~~~~~~~^~~~~~
/usr/lib/gcc/x86_64-linux-gnu/8/include/immintrin.h:129:1: error: inlining failed in call to always_inline ‘int _rdrand16_step(short unsigned int*)’: target specific option mismatch
 _rdrand16_step (unsigned short *__P)
 ^~~~~~~~~~~~~~
otp_s7c.cpp:148:23: note: called from here
         _rdrand16_step(&val);
         ~~~~~~~~~~~~~~^~~~~~

Answer 1

这是一个有点误导性的错误消息，因为您实际上并没有告诉编译器您的目标体系结构支持 RDRAND 指令(据我所知，这里的重要部分是“目标特定选项”不匹配”部分在最后)。

将 -mrdrnd 添加到编译器标志似乎可以解决问题。

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^{比较 Compiler Explorer 上的示例 with和 without旗帜}