[SYCL] Complete SYCL_INTEL_accessor_simplification extension implementation (#1943)

This second patch finishes the implementation of SYCL_INTEL_accessor_simplification extension.

It adds:

* `get_host_accessor`  to buffer
* adds overloads for `get_access` to enable deduction guide
* refactored test, as requested in this PR: #1838
* updated deduction guides, based on limitations found via refactored tests

Author: iburyl

sycl/include/CL/sycl/accessor.hpp

@@ -1223,42 +1223,69 @@ class accessor :
 
 #if __cplusplus > 201402L
 
-template <typename DataT, int Dimensions, typename AllocatorT, typename... Ts>
-accessor(buffer<DataT, Dimensions, AllocatorT>, Ts...)
+template <typename DataT, int Dimensions, typename AllocatorT>
+accessor(buffer<DataT, Dimensions, AllocatorT>)
     ->accessor<DataT, Dimensions, access::mode::read_write,
                target::global_buffer, access::placeholder::true_t>;
 
-template <typename DataT, int Dimensions, typename AllocatorT, typename... Ts>
-accessor(buffer<DataT, Dimensions, AllocatorT>, handler, Ts...)
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1>
+accessor(buffer<DataT, Dimensions, AllocatorT>, Type1)
+    ->accessor<DataT, Dimensions, detail::deduceAccessMode<Type1, Type1>(),
+               detail::deduceAccessTarget<Type1, Type1>(target::global_buffer),
+               access::placeholder::true_t>;
+
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1,
+          typename Type2>
+accessor(buffer<DataT, Dimensions, AllocatorT>, Type1, Type2)
+    ->accessor<DataT, Dimensions, detail::deduceAccessMode<Type1, Type2>(),
+               detail::deduceAccessTarget<Type1, Type2>(target::global_buffer),
+               access::placeholder::true_t>;
+
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1,
+          typename Type2, typename Type3>
+accessor(buffer<DataT, Dimensions, AllocatorT>, Type1, Type2, Type3)
+    ->accessor<DataT, Dimensions, detail::deduceAccessMode<Type2, Type3>(),
+               detail::deduceAccessTarget<Type2, Type3>(target::global_buffer),
+               access::placeholder::true_t>;
+
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1,
+          typename Type2, typename Type3, typename Type4>
+accessor(buffer<DataT, Dimensions, AllocatorT>, Type1, Type2, Type3, Type4)
+    ->accessor<DataT, Dimensions, detail::deduceAccessMode<Type3, Type4>(),
+               detail::deduceAccessTarget<Type3, Type4>(target::global_buffer),
+               access::placeholder::true_t>;
+
+template <typename DataT, int Dimensions, typename AllocatorT>
+accessor(buffer<DataT, Dimensions, AllocatorT>, handler)
     ->accessor<DataT, Dimensions, access::mode::read_write,
                target::global_buffer, access::placeholder::false_t>;
 
-template <typename DataT, int Dimensions, typename AllocatorT,
-          access_mode AccessMode, typename... Ts>
-accessor(buffer<DataT, Dimensions, AllocatorT>, Ts..., mode_tag_t<AccessMode>,
-         property_list = {})
-    ->accessor<DataT, Dimensions, AccessMode, target::global_buffer,
-               access::placeholder::true_t>;
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1>
+accessor(buffer<DataT, Dimensions, AllocatorT>, handler, Type1)
+    ->accessor<DataT, Dimensions, detail::deduceAccessMode<Type1, Type1>(),
+               detail::deduceAccessTarget<Type1, Type1>(target::global_buffer),
+               access::placeholder::false_t>;
 
-template <typename DataT, int Dimensions, typename AllocatorT,
-          access_mode AccessMode, typename... Ts>
-accessor(buffer<DataT, Dimensions, AllocatorT>, handler, Ts...,
-         mode_tag_t<AccessMode>, property_list = {})
-    ->accessor<DataT, Dimensions, AccessMode, target::global_buffer,
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1,
+          typename Type2>
+accessor(buffer<DataT, Dimensions, AllocatorT>, handler, Type1, Type2)
+    ->accessor<DataT, Dimensions, detail::deduceAccessMode<Type1, Type2>(),
+               detail::deduceAccessTarget<Type1, Type2>(target::global_buffer),
                access::placeholder::false_t>;
 
-template <typename DataT, int Dimensions, typename AllocatorT,
-          access_mode AccessMode, target AccessTarget, typename... Ts>
-accessor(buffer<DataT, Dimensions, AllocatorT>, Ts...,
-         mode_target_tag_t<AccessMode, AccessTarget>, property_list = {})
-    ->accessor<DataT, Dimensions, AccessMode, AccessTarget,
-               access::placeholder::true_t>;
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1,
+          typename Type2, typename Type3>
+accessor(buffer<DataT, Dimensions, AllocatorT>, handler, Type1, Type2, Type3)
+    ->accessor<DataT, Dimensions, detail::deduceAccessMode<Type2, Type3>(),
+               detail::deduceAccessTarget<Type2, Type3>(target::global_buffer),
+               access::placeholder::false_t>;
 
-template <typename DataT, int Dimensions, typename AllocatorT,
-          access_mode AccessMode, target AccessTarget, typename... Ts>
-accessor(buffer<DataT, Dimensions, AllocatorT>, handler, Ts...,
-         mode_target_tag_t<AccessMode, AccessTarget>, property_list = {})
-    ->accessor<DataT, Dimensions, AccessMode, AccessTarget,
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1,
+          typename Type2, typename Type3, typename Type4>
+accessor(buffer<DataT, Dimensions, AllocatorT>, handler, Type1, Type2, Type3,
+         Type4)
+    ->accessor<DataT, Dimensions, detail::deduceAccessMode<Type3, Type4>(),
+               detail::deduceAccessTarget<Type3, Type4>(target::global_buffer),
                access::placeholder::false_t>;
 
 #endif
@@ -1658,15 +1685,32 @@ class host_accessor
 
 #if __cplusplus > 201402L
 
-template <typename DataT, int Dimensions, typename AllocatorT, typename... Ts>
-host_accessor(buffer<DataT, Dimensions, AllocatorT>, Ts...)
+template <typename DataT, int Dimensions, typename AllocatorT>
+host_accessor(buffer<DataT, Dimensions, AllocatorT>)
     ->host_accessor<DataT, Dimensions, access::mode::read_write>;
 
-template <typename DataT, int Dimensions, typename AllocatorT,
-          access_mode AccessMode, typename... Ts>
-host_accessor(buffer<DataT, Dimensions, AllocatorT>, Ts...,
-              mode_tag_t<AccessMode>, property_list = {})
-    ->host_accessor<DataT, Dimensions, AccessMode>;
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1>
+host_accessor(buffer<DataT, Dimensions, AllocatorT>, Type1)
+    ->host_accessor<DataT, Dimensions,
+                    detail::deduceAccessMode<Type1, Type1>()>;
+
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1,
+          typename Type2>
+host_accessor(buffer<DataT, Dimensions, AllocatorT>, Type1, Type2)
+    ->host_accessor<DataT, Dimensions,
+                    detail::deduceAccessMode<Type1, Type2>()>;
+
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1,
+          typename Type2, typename Type3>
+host_accessor(buffer<DataT, Dimensions, AllocatorT>, Type1, Type2, Type3)
+    ->host_accessor<DataT, Dimensions,
+                    detail::deduceAccessMode<Type2, Type3>()>;
+
+template <typename DataT, int Dimensions, typename AllocatorT, typename Type1,
+          typename Type2, typename Type3, typename Type4>
+host_accessor(buffer<DataT, Dimensions, AllocatorT>, Type1, Type2, Type3, Type4)
+    ->host_accessor<DataT, Dimensions,
+                    detail::deduceAccessMode<Type3, Type4>()>;
 
 #endif
 

sycl/include/CL/sycl/buffer.hpp

@@ -277,6 +277,23 @@ class buffer {
                                                   accessOffset);
   }
 
+#if __cplusplus > 201402L
+
+  template <typename... Ts> auto get_access(Ts... args) {
+    return accessor{*this, args...};
+  }
+
+  template <typename... Ts>
+  auto get_access(handler &commandGroupHandler, Ts... args) {
+    return accessor{*this, commandGroupHandler, args...};
+  }
+
+  template <typename... Ts> auto get_host_access(Ts... args) {
+    return host_accessor{*this, args...};
+  }
+
+#endif
+
   template <typename Destination = std::nullptr_t>
   void set_final_data(Destination finalData = nullptr) {
     impl->set_final_data(finalData);

sycl/include/CL/sycl/detail/accessor_impl.hpp

@@ -183,6 +183,57 @@ using Requirement = AccessorImplHost;
 
 void __SYCL_EXPORT addHostAccessorAndWait(Requirement *Req);
 
+#if __cplusplus > 201402L
+
+template <typename MayBeTag1, typename MayBeTag2>
+constexpr access::mode deduceAccessMode() {
+  // property_list = {} is not properly detected by deduction guide,
+  // when parameter is passed without curly braces: access(buffer, noinit)
+  // thus simplest approach is to check 2 last arguments for being a tag
+  if constexpr (std::is_same<MayBeTag1,
+                             mode_tag_t<access::mode::read>>::value ||
+                std::is_same<MayBeTag2,
+                             mode_tag_t<access::mode::read>>::value) {
+    return access::mode::read;
+  }
+
+  if constexpr (std::is_same<MayBeTag1,
+                             mode_tag_t<access::mode::write>>::value ||
+                std::is_same<MayBeTag2,
+                             mode_tag_t<access::mode::write>>::value) {
+    return access::mode::write;
+  }
+
+  if constexpr (
+      std::is_same<MayBeTag1,
+                   mode_target_tag_t<access::mode::read,
+                                     access::target::constant_buffer>>::value ||
+      std::is_same<MayBeTag2,
+                   mode_target_tag_t<access::mode::read,
+                                     access::target::constant_buffer>>::value) {
+    return access::mode::read;
+  }
+
+  return access::mode::read_write;
+}
+
+template <typename MayBeTag1, typename MayBeTag2>
+constexpr access::target deduceAccessTarget(access::target defaultTarget) {
+  if constexpr (
+      std::is_same<MayBeTag1,
+                   mode_target_tag_t<access::mode::read,
+                                     access::target::constant_buffer>>::value ||
+      std::is_same<MayBeTag2,
+                   mode_target_tag_t<access::mode::read,
+                                     access::target::constant_buffer>>::value) {
+    return access::target::constant_buffer;
+  }
+
+  return defaultTarget;
+}
+
+#endif
+
 } // namespace detail
 } // namespace sycl
 } // __SYCL_INLINE_NAMESPACE(cl)

sycl/include/CL/sycl/detail/buffer_impl.hpp

@@ -31,6 +31,8 @@ template <typename DataT, int Dimensions, access::mode AccessMode,
 class accessor;
 template <typename T, int Dimensions, typename AllocatorT, typename Enable>
 class buffer;
+template <typename DataT, int Dimensions, access::mode AccessMode>
+class host_accessor;
 
 using buffer_allocator = detail::sycl_memory_object_allocator;