[SYCL] Add support for get_backend() API (#1879)

This API returns the backend associated with a platform.
A LIT test has also been added.

Signed-off-by: Gail Lyons <[email protected]>

Author: glyons-intel

sycl/include/CL/sycl/backend_types.hpp

@@ -10,12 +10,34 @@
 
 #include <CL/sycl/detail/defines.hpp>
 
+#include <fstream>
+#include <iostream>
+#include <istream>
+#include <string>
+
 __SYCL_INLINE_NAMESPACE(cl) {
 namespace sycl {
 
 enum class backend : char { host, opencl, level0, cuda };
 
 template <backend name, typename SYCLObjectT> struct interop;
 
+inline std::ostream &operator<<(std::ostream &Out, backend be) {
+  switch (be) {
+  case backend::host:
+    Out << std::string("host");
+    break;
+  case backend::opencl:
+    Out << std::string("opencl");
+    break;
+  case backend::level0:
+    Out << std::string("level-zero");
+    break;
+  case backend::cuda:
+    Out << std::string("cuda");
+  }
+  return Out;
+}
+
 } // namespace sycl
 } // __SYCL_INLINE_NAMESPACE(cl)

sycl/include/CL/sycl/platform.hpp

@@ -102,6 +102,11 @@ class __SYCL_EXPORT platform {
   /// \return a vector of all available SYCL platforms.
   static vector_class<platform> get_platforms();
 
+  /// Returns the backend associated with this platform.
+  ///
+  /// \return the backend associated with this platform
+  backend get_backend() const noexcept;
+
   /// Gets the native handle of the SYCL platform.
   ///
   /// \return a native handle, the type of which defined by the backend.

sycl/source/detail/platform_impl.hpp

@@ -106,6 +106,9 @@ class platform_impl {
   /// \return a vector of all available SYCL platforms.
   static vector_class<platform> get_platforms();
 
+  // \return the Backend associated with this platform.
+  backend get_backend() const noexcept { return getPlugin().getBackend(); }
+
   // \return the Plugin associated with this platform.
   const plugin &getPlugin() const {
     assert(!MHostPlatform && "Plugin is not available for Host.");

sycl/source/platform.cpp

@@ -43,6 +43,8 @@ vector_class<platform> platform::get_platforms() {
   return detail::platform_impl::get_platforms();
 }
 
+backend platform::get_backend() const noexcept { return impl->get_backend(); }
+
 template <info::platform param>
 typename info::param_traits<info::platform, param>::return_type
 platform::get_info() const {

sycl/test/abi/sycl_symbols_linux.dump

@@ -3523,6 +3523,7 @@ _ZNK2cl4sycl7sampler19get_addressing_modeEv
 _ZNK2cl4sycl7sampler33get_coordinate_normalization_modeEv
 _ZNK2cl4sycl7samplereqERKS1_
 _ZNK2cl4sycl7samplerneERKS1_
+_ZNK2cl4sycl8platform11get_backendEv
 _ZNK2cl4sycl8platform11get_devicesENS0_4info11device_typeE
 _ZNK2cl4sycl8platform13has_extensionERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE
 _ZNK2cl4sycl8platform3getEv

sycl/test/basic_tests/get_backend.cpp

@@ -0,0 +1,40 @@
+// RUN: %clangxx -fsycl %s -o %t.out
+// RUN: %t.out
+//
+//==----------------- get_backend.cpp ------------------------==//
+// This is a test of get_backend().
+// Also prints handy info about the system.
+// Do not set SYCL_BE.  We do not want the preferred backend.
+//==----------------------------------------------------------==//
+
+#include <CL/sycl.hpp>
+#include <CL/sycl/backend_types.hpp>
+#include <iostream>
+
+using namespace cl::sycl;
+
+bool check(backend be) {
+  switch (be) {
+  case backend::opencl:
+  case backend::level0:
+  case backend::cuda:
+  case backend::host:
+    return true;
+  default:
+    return false;
+  }
+  return false;
+}
+
+int main() {
+  for (const auto &plt : platform::get_platforms()) {
+    if (!plt.is_host()) {
+      if (check(plt.get_backend()) == false) {
+        std::cout << "Failed" << std::endl;
+        return 1;
+      }
+    }
+  }
+  std::cout << "Passed" << std::endl;
+  return 0;
+}