From 1ffccf2daba3dab31c4a2dd12cf920ef37103c81 Mon Sep 17 00:00:00 2001
From: Sam Yates <yates@cscs.ch>
Date: Thu, 6 Sep 2018 10:12:07 +0200
Subject: [PATCH] Clarify vectorization-enabled build errors. (#588)
Fixes #587.
* Eliminate Clang warnings from GCC-tree-optimization bug work-around.
* Error with static-assert if simd type is used with a missing simd abi.
* Clarify install documentation regarding use of ARB_VECTORIZE with ARB_ARCH.
---
doc/install.rst | 9 +++++----
include/arbor/simd/simd.hpp | 2 ++
include/arbor/util/compat.hpp | 2 +-
3 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/doc/install.rst b/doc/install.rst
index c7c7cd01..9bf9915e 100644
--- a/doc/install.rst
+++ b/doc/install.rst
@@ -287,16 +287,17 @@ Vectorization
-------------
Explicit vectorization of computational kernels can be enabled in Arbor by setting the
-``ARB_VECTORIZE`` CMake flag:
+``ARB_VECTORIZE`` CMake flag. This option is typically used in conjunction with the
+``ARB_ARCH`` option to specify the target architecture: without SIMD support in Arbor
+for the architecture, enabling ``ARB_VECTORIZE`` will lead to a compilation error.
.. code-block:: bash
- cmake -DARB_VECTORIZE=ON
+ cmake -DARB_VECTORIZE=ON -DARB_ARCH=native
With this flag set, the library will use architecture-specific vectorization intrinsics
to implement these kernels. Arbor currently has vectorization support for x86 architectures
-with AVX, AVX2 or AVX512 ISA extensions. Enabling the `ARB_VECTORIZE` option for a target
-without support in Arbor will give a compilation error.
+with AVX, AVX2 or AVX512 ISA extensions.
.. _gpu:
diff --git a/include/arbor/simd/simd.hpp b/include/arbor/simd/simd.hpp
index fff3ff08..4a319216 100644
--- a/include/arbor/simd/simd.hpp
+++ b/include/arbor/simd/simd.hpp
@@ -56,6 +56,8 @@ namespace simd_detail {
template <typename Impl>
struct simd_impl {
+ static_assert(!std::is_void<Impl>::value, "no such SIMD ABI supported");
+
// Type aliases:
//
// scalar_type internal value type in one simd lane,
diff --git a/include/arbor/util/compat.hpp b/include/arbor/util/compat.hpp
index 46eacb06..531f7f73 100644
--- a/include/arbor/util/compat.hpp
+++ b/include/arbor/util/compat.hpp
@@ -42,7 +42,7 @@ inline void compiler_barrier_if_icc_leq(unsigned ver) {
// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85597
template <typename T>
-#if defined(__GNUC__) &&\
+#if !defined(__clang__) && defined(__GNUC__) &&\
( __GNUC__<6 ||\
(__GNUC__==6 && __GNUC_MINOR__*100 + __GNUC_PATCHLEVEL__ < 401) ||\
(__GNUC__==7 && __GNUC_MINOR__*100 + __GNUC_PATCHLEVEL__ < 301) ||\
--
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