x86 Dispatcher

Macros
#define	XXH_DISPATCH_SCALAR   1
	Enables/dispatching the scalar code path. More...
#define	XXH_DISPATCH_AVX2   0
	Enables/disables dispatching for AVX2. More...
#define	XXH_DISPATCH_AVX512   0
	Enables/disables dispatching for AVX512. More...

Detailed Description

Macro Definition Documentation

XXH_DISPATCH_SCALAR

#define XXH_DISPATCH_SCALAR   1

Enables/dispatching the scalar code path.

If this is defined to 0, SSE2 support is assumed. This reduces code size when the scalar path is not needed.

This is automatically defined to 0 when...

• SSE2 support is enabled in the compiler
• Targeting x86_64
• Targeting Android x86
• Targeting macOS

XXH_DISPATCH_AVX2

#define XXH_DISPATCH_AVX2   0

Enables/disables dispatching for AVX2.

This is automatically detected if it is not defined.

• GCC 4.7 and later are known to support AVX2, but >4.9 is required for to get the AVX2 intrinsics and typedefs without -mavx -mavx2.
• Visual Studio 2013 Update 2 and later are known to support AVX2.
• The GCC/Clang internal header <avx2intrin.h> is detected. While this is not allowed to be included directly, it still appears in the builtin include path and is detectable with __has_include.

See also

XXH_AVX2

XXH_DISPATCH_AVX512

#define XXH_DISPATCH_AVX512   0

Enables/disables dispatching for AVX512.

Automatically detected if one of the following conditions is met:

• GCC 4.9 and later are known to support AVX512.
• Visual Studio 2017 and later are known to support AVX2.
• The GCC/Clang internal header <avx512fintrin.h> is detected. While this is not allowed to be included directly, it still appears in the builtin include path and is detectable with __has_include.

See also

XXH_AVX512