Header files for x86 SIMD intrinsics

Question

Which header files provide the intrinsics for the different x86 SIMD instruction set extensions (MMX, SSE, AVX, ...)? It seems impossible to find such a list online. Correct

Answer 1

The header name depends on your compiler and target architecture.

• For Microsoft C++ (targeting x86, x86-64 or ARM) and Intel C/C++ Compiler for Windows use intrin.h
• For gcc/clang/icc targeting x86/x86-64 use x86intrin.h
• For gcc/clang/armcc targeting ARM with NEON use arm_neon.h
• For gcc/clang/armcc targeting ARM with WMMX use mmintrin.h
• For gcc/clang/xlcc targeting PowerPC with VMX (aka Altivec) and/or VSX use altivec.h
• For gcc/clang targeting PowerPC with SPE use spe.h

You can handle all these cases with conditional preprocessing directives:

#if defined(_MSC_VER)
     /* Microsoft C/C++-compatible compiler */
     #include 
#elif defined(__GNUC__) && (defined(__x86_64__) || defined(__i386__))
     /* GCC-compatible compiler, targeting x86/x86-64 */
     #include 
#elif defined(__GNUC__) && defined(__ARM_NEON__)
     /* GCC-compatible compiler, targeting ARM with NEON */
     #include 
#elif defined(__GNUC__) && defined(__IWMMXT__)
     /* GCC-compatible compiler, targeting ARM with WMMX */
     #include 
#elif (defined(__GNUC__) || defined(__xlC__)) && (defined(__VEC__) || defined(__ALTIVEC__))
     /* XLC or GCC-compatible compiler, targeting PowerPC with VMX/VSX */
     #include 
#elif defined(__GNUC__) && defined(__SPE__)
     /* GCC-compatible compiler, targeting PowerPC with SPE */
     #include 
#endif