GCC and x86intrin.h header

[Ian Lance Taylor]

Erotavlas_turbo@libero.it writes:

> I read in the manual of GCC the following line:
> <x86intrin.h> // new intrinsic header file, it should be included before using any IA-32/x86-64 intrinsics.
> What does it mean? I have to explicitly include this library in my code if I want to use the intrinsic functions like ssex or mcrc32 etc.

This question would be more appropriate for the mailing list
gcc-help@gcc.gnu.org than for gcc@.  The gcc@ mailing list is for
discussions related to the development of gcc itself.  Please take any
followups to gcc-help.  Thanks.

To answer your question: the <x86intrin.h> header file provides
definitions for all intrinsic functions which are relevant to the target
processor.  The intrinsic functions are the ones with names like
_mm_crc32_u8.  You are not required to #include <x86intrin.h>.  But it
is a more reliable mechanism than the older one of remembering that
_mm_crc32_u8 is defined in <smmintrin.h>.

Ian