[libcxx] implement <simd> ABI for Clang/GCC vector extension, constructors, copy_from and copy_to.

Summary:
This patch adds a new macro _LIBCPP_HAS_NO_VECTOR_EXTENSION for detecting
whether a vector extension (\_\_attribute\_\_((vector_size(num_bytes)))) is
available.

On the top of that, this patch implements the following API:
* all constructors
* operator[]
* copy_from
* copy_to

It also defines simd_abi::native to use vector extension, if available.
In GCC and Clang, certain values with vector extension are passed by registers,
instead of memory.

Based on D41148.

Reviewers: mclow.lists, EricWF

Subscribers: cfe-commits, MaskRay, lichray, sanjoy

Differential Revision: https://reviews.llvm.org/D41376

llvm-svn: 338309

1 files changed, 28 insertions, 0 deletions

diff --git a/libcxx/test/std/experimental/simd/simd.cons/default.pass.cpp b/libcxx/test/std/experimental/simd/simd.cons/default.pass.cpp
new file mode 100644
index 00000000000..0f12eced0aa
--- /dev/null
+++ b/libcxx/test/std/experimental/simd/simd.cons/default.pass.cpp
@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <experimental/simd>
+//
+// [simd.class]
+// simd() = default;
+
+#include <cstdint>
+#include <experimental/simd>
+
+namespace ex = std::experimental::parallelism_v2;
+
+int main() {
+  static_assert(ex::native_simd<int32_t>().size() > 0, "");
+  static_assert(ex::fixed_size_simd<int32_t, 4>().size() == 4, "");
+  static_assert(ex::fixed_size_simd<int32_t, 5>().size() == 5, "");
+  static_assert(ex::fixed_size_simd<int32_t, 1>().size() == 1, "");
+  static_assert(ex::fixed_size_simd<char, 32>().size() == 32, "");
+}