joshblake / libsimdpp

Header-only zero-overhead C++ wrapper for SIMD intrinsics of multiple instruction sets

Overview

libsimdpp is a portable header-only zero-overhead C++ wrapper around single-instruction multiple-data (SIMD) intrinsics found in many compilers. The library presents a single interface over several instruction sets in such a way that the same source code may be compiled for different instruction sets. The resulting object files then may be hooked into internal dynamic dispatch mechanism.

The library resolves differences between instruction sets by implementing the missing functionality as a combination of several intrinsics. Moreover, the library supplies a lot of additional, commonly used functionality, such as various variants of matrix transpositions, interleaving loads/stores, optimized compile-time shuffling instructions, etc. Each of these are implemented in the most efficient manner for the target instruction set. Finally, it's possible to fall back to native intrinsics when necessary, without compromising maintanability.

The library sits somewhere in the middle between programming directly in intrinsics and even higher-level SIMD libraries. As much control as possible is given to the developer, so that it's possible to exactly predict what code the compiler will generate.

No API-breaking changes are planned for the foreseeable future.

Compiler and instruction set support

• This describes the current branch only which may be unstable or otherwise unfit for use. For available releases please see the libsimdpp wiki.

The library supports the following architectures and instruction sets:

• x86, x86-64: SSE2, SSE3, SSSE3, SSE4.1, AVX, AVX2, FMA3, FMA4, AVX-512F, XOP
• ARM, ARM64: NEON
• PowerPC: Altivec

The primary development of the library happens in C++11. A C++98-compatible version of the library is provided on the cxx98 branch.

• C++11 version:

  • GCC: 4.8-5.3
  • Clang: 3.3-3.8
  • MSVC: 2013
  • ICC: 2013, 2015

• C++98 version

  • GCC: 4.4-5.3
  • Clang: 3.3-3.8
  • MSVC: 2013
  • ICC: 2013, 2015

Clang 3.3 is not supported on ARM. MSVC and ICC are only supported on x86 and x86-64. Any compiler bugs are either worked-around or support for broken instruction set on the particular compiler version is disabled -- the bugs are not exposed under any circumstances.

Newer versions of the aforementioned compilers will generally work with either C++11 or C++98 version of the library. Older versions of these compilers will generally work with the C++98 version of the library.

Documentation

Online documentation is provided here.

License

The library is distributed under the Boost Software License, Version 1.0

Boost Software License - Version 1.0 - August 17th, 2003

Permission is hereby granted, free of charge, to any person or organization obtaining a copy of the software and accompanying documentation covered by this license (the "Software") to use, reproduce, display, distribute, execute, and transmit the Software, and to prepare derivative works of the Software, and to permit third-parties to whom the Software is furnished to do so, all subject to the following:

The copyright notices in the Software and this entire statement, including the above license grant, this restriction and the following disclaimer, must be included in all copies of the Software, in whole or in part, and all derivative works of the Software, unless such copies or derivative works are solely in the form of machine-executable object code generated by a source language processor.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.