[SYCL] Change signature of host_accessor::get_pointer for SYCL 2020 (#8109)

SYCL 2020 specifies that the `get_pointer` member should now return a
raw pointer for based on `value_type` and should be `noexcept`. This
commit changes the signature of `get_pointer` for host accessors.

Note that `AccessorBaseHost::getPtr` cannot be made `noexcept` currently
as it would be an ABI break. This does not limit the functionality of
these changes, but should be changed during next ABI break.

Signed-off-by: Larsen, Steffen <[email protected]>

Author: steffenlarsen

sycl/include/sycl/accessor.hpp

@@ -1098,7 +1098,7 @@ class __SYCL_EBO __SYCL_SPECIAL_CLASS __SYCL_TYPE(accessor) accessor :
   // range and offset are not supported.
   void __init_esimd(ConcreteASPtrType Ptr) { MData = Ptr; }
 
-  ConcreteASPtrType getQualifiedPtr() const { return MData; }
+  ConcreteASPtrType getQualifiedPtr() const noexcept { return MData; }
 
   template <typename DataT_, int Dimensions_, access::mode AccessMode_,
             access::target AccessTarget_, access::placeholder IsPlaceholder_,
@@ -1176,7 +1176,7 @@ class __SYCL_EBO __SYCL_SPECIAL_CLASS __SYCL_TYPE(accessor) accessor :
                sizeof(PtrType) - sizeof(detail::AccessorBaseHost) -
                sizeof(MAccData)];
 
-  PtrType getQualifiedPtr() const {
+  PtrType getQualifiedPtr() const noexcept {
     if constexpr (IsHostBuf)
       return reinterpret_cast<PtrType>(MAccData->MData);
     else
@@ -2026,7 +2026,12 @@ class __SYCL_EBO __SYCL_SPECIAL_CLASS __SYCL_TYPE(accessor) accessor :
   template <access::target AccessTarget_ = AccessTarget,
             typename = detail::enable_if_t<AccessTarget_ ==
                                            access::target::host_buffer>>
-  DataT *get_pointer() const {
+#if SYCL_LANGUAGE_VERSION >= 202001
+  std::add_pointer_t<value_type> get_pointer() const noexcept
+#else
+  DataT *get_pointer() const
+#endif
+  {
     return getPointerAdjusted();
   }
 
@@ -2129,7 +2134,7 @@ class __SYCL_EBO __SYCL_SPECIAL_CLASS __SYCL_TYPE(accessor) accessor :
 
 private:
 #ifdef __SYCL_DEVICE_ONLY__
-  size_t getTotalOffset() const {
+  size_t getTotalOffset() const noexcept {
     size_t TotalOffset = 0;
     detail::dim_loop<Dimensions>([&, this](size_t I) {
       TotalOffset = TotalOffset * impl.MemRange[I];
@@ -2148,7 +2153,7 @@ class __SYCL_EBO __SYCL_SPECIAL_CLASS __SYCL_TYPE(accessor) accessor :
   // but for get_pointer() we must return the original pointer.
   // On device, getQualifiedPtr() returns MData, so we need to backjust it.
   // On host, getQualifiedPtr() does not return MData, no need to adjust.
-  auto getPointerAdjusted() const {
+  auto getPointerAdjusted() const noexcept {
 #ifdef __SYCL_DEVICE_ONLY__
     return getQualifiedPtr() - getTotalOffset();
 #else

sycl/test/basic_tests/accessor/host_accessor_get_pointer_type.cpp

@@ -0,0 +1,35 @@
+// RUN: %clangxx -fsycl -fsyntax-only -sycl-std=2020 %s
+
+// Tests the type of the get_pointer method of host_accessor.
+
+#include <sycl/sycl.hpp>
+
+#include <type_traits>
+
+template <typename DataT, int Dims, sycl::access::mode Mode>
+void CheckHostAccessor() {
+  using HostAccessorT = sycl::host_accessor<DataT, Dims, Mode>;
+  using HostAccessorGetPointerT =
+      decltype(std::declval<HostAccessorT>().get_pointer());
+  static_assert(
+      std::is_same_v<HostAccessorGetPointerT,
+                     std::add_pointer_t<typename HostAccessorT::value_type>>);
+}
+
+template <typename DataT, int Dims> void CheckHostAccessorForModes() {
+  CheckHostAccessor<DataT, Dims, sycl::access::mode::read>();
+  CheckHostAccessor<DataT, Dims, sycl::access::mode::read_write>();
+  CheckHostAccessor<DataT, Dims, sycl::access::mode::write>();
+}
+
+template <typename DataT> void CheckHostAccessorForAllDimsAndModes() {
+  CheckHostAccessorForModes<DataT, 1>();
+  CheckHostAccessorForModes<DataT, 2>();
+  CheckHostAccessorForModes<DataT, 3>();
+}
+
+int main() {
+  CheckHostAccessorForAllDimsAndModes<int>();
+  CheckHostAccessorForAllDimsAndModes<const int>();
+  return 0;
+}