MSVC 2019 _fxrstor64 and _fxsave64 intrinsics availability-CodePudding

What are the minimum preprocessor checks I need to make to be sure the compiler is MSVC2019 and that the _fxrstor64 and _fxsave64 intrinsics are available for use?

CodePudding user response：

To check that you have (at least) the MSVC 2019 compiler, you should use the following:

#if !defined(_MSC_VER) || (_MSC_VER < 1900)
#error "Not MSVC or MSVC is too old"
#endif

For the _fxrstor64 and _fxsave64 intrinsics to be available to MSVC, you need to check that the "immintrin.h" header has been included:

#ifndef _INCLUDED_IMM
#error "Haven't included immintrin.h"
#endif

You also (perhaps obviously) need to be compiling for the x64 architecture:

#ifndef _M_X64
#error "Wrong target architetcture!"
#endif

You could put all those checks into one test, as follows:

#if defined(_MSC_VER) && (_MSC_VER >= 1900) && defined(_INCLUDED_IMM) && defined(_M_X64)
    // OK
#else
    #error "Wrong compiler or target architecture, or missing header file."
#endif

Note that the _INCLUDED_IMM token is specific to the MSVC compiler; for example, clang-cl uses __IMMINTRIN_H. So, if you also want to enable other, MSVC-compatible compilers, you'll need to add optional checks for each of their own tokens (by looking in the "immintrin.h" header each one uses).