1.. title:: clang-tidy - portability-simd-intrinsics
2
3portability-simd-intrinsics
4===========================
5
6Finds SIMD intrinsics calls and suggests ``std::experimental::simd`` (`P0214`_)
7alternatives.
8
9If the option :option:`Suggest` is set to `true`, for
10
11.. code-block:: c++
12
13  _mm_add_epi32(a, b); // x86
14  vec_add(a, b);       // Power
15
16the check suggests an alternative: ``operator+`` on ``std::experimental::simd``
17objects.
18
19Otherwise, it just complains the intrinsics are non-portable (and there are
20`P0214`_ alternatives).
21
22Many architectures provide SIMD operations (e.g. x86 SSE/AVX, Power AltiVec/VSX,
23ARM NEON). It is common that SIMD code implementing the same algorithm, is
24written in multiple target-dispatching pieces to optimize for different
25architectures or micro-architectures.
26
27The C++ standard proposal `P0214`_ and its extensions cover many common SIMD
28operations. By migrating from target-dependent intrinsics to `P0214`_
29operations, the SIMD code can be simplified and pieces for different targets can
30be unified.
31
32Refer to `P0214`_ for introduction and motivation for the data-parallel standard
33library.
34
35Options
36-------
37
38.. option:: Suggest
39
40   If this option is set to `true` (default is `false`), the check will suggest
41   `P0214`_ alternatives, otherwise it only points out the intrinsic function is
42   non-portable.
43
44.. option:: Std
45
46   The namespace used to suggest `P0214`_ alternatives. If not specified, `std::`
47   for `-std=c++20` and `std::experimental::` for `-std=c++11`.
48
49.. _P0214: https://wg21.link/p0214
50