Merge pull request #2246 from JohanMabille/align

Testing alignment

Author: JohanMabille

.azure-pipelines/azure-pipelines-linux-clang.yml

@@ -14,6 +14,9 @@ jobs:
           llvm_version: '8'
         clang_9:
           llvm_version: '9'
+        clang_10:
+          llvm_version: '10'
+          disable_xsimd: 1
     pool:
       vmImage: ubuntu-16.04
     variables:

docs/source/xsimd.rst

@@ -18,19 +18,19 @@ Alignment of fixed-size members
 
 If you define a structure having members of fixed-size xtensor types,
 you must ensure that the buffers properly aligned.
-For this you can use the macro ``XTENSOR_SELECT_ALIGN`` available in
+For this you can use the macro ``XTENSOR_FIXED_ALIGN`` available in
 ``xtensor/xtensor_config.hpp``.
 Consider the following example:
 
 .. code-block:: cpp
 
     template <typename T>
-    class alignas(XTENSOR_SELECT_ALIGN(T)) Foo
+    class alignas(XTENSOR_FIXED_ALIGN) Foo
     {
     public:
 
-        using allocator_type = std::conditional_t<XTENSOR_SELECT_ALIGN(T) != 0,
-                                                  xt_simd::aligned_allocator<T, XTENSOR_SELECT_ALIGN(T)>,
+        using allocator_type = std::conditional_t<XTENSOR_FIXED_ALIGN != 0,
+                                                  xt_simd::aligned_allocator<T, XTENSOR_FIXED_ALIGN>,
                                                   std::allocator<T>>;
 
         Foo(T fac) : m_fac(fac)

include/xtensor/xtensor_config.hpp

@@ -114,6 +114,10 @@
 #define XTENSOR_SELECT_ALIGN(T) (XTENSOR_DEFAULT_ALIGNMENT != 0 ? XTENSOR_DEFAULT_ALIGNMENT : alignof(T))
 #endif
 
+#ifndef XTENSOR_FIXED_ALIGN
+#define XTENSOR_FIXED_ALIGN XTENSOR_SELECT_ALIGN(void*)
+#endif
+
 #ifdef IN_DOXYGEN
 namespace xtl
 {

test/test_xsimd.cpp

@@ -15,12 +15,12 @@
 #include "xtensor/xtensor_config.hpp"
 
 template <typename T>
-class alignas(XTENSOR_SELECT_ALIGN(T)) Foo
+class alignas(XTENSOR_FIXED_ALIGN) Foo
 {
 public:
 
-    using allocator_type = std::conditional_t<XTENSOR_SELECT_ALIGN(T) != 0,
-                                              xt_simd::aligned_allocator<T, XTENSOR_SELECT_ALIGN(T)>,
+    using allocator_type = std::conditional_t<XTENSOR_FIXED_ALIGN != 0,
+                                              xt_simd::aligned_allocator<T, XTENSOR_FIXED_ALIGN>,
                                               std::allocator<T>>;
 
     Foo(T fac) : m_fac(fac)
@@ -49,3 +49,4 @@ namespace xt
         EXPECT_TRUE(xt::sum(foo.get())() == fac * 10 * 10);
     }
 }
+