[SYCL][CUDA] CUDA Device selection changes

* Removes NVIDIA OpenCL from the available list of platforms
* CUDA backend is available only if SYCL_BE=PI_CUDA is set

Signed-off-by: Ruyman Reyes <ruyman@codeplay.com>

Author: Ruyman Reyes

sycl/source/detail/platform_impl.cpp

@@ -202,29 +202,29 @@ static bool isDeviceInvalidForBe(const device &Device) {
   if (Device.is_host())
     return false;
 
-  // Taking the version information from the platform gives us more useful
-  // information than the driver_version of the device.
+  // Retrieve Platform version to identify CUDA OpenCL platform
+  // String:  OpenCL 1.2 CUDA <version>
   const platform platform = Device.get_info<info::device::platform>();
   const std::string platformVersion =
       platform.get_info<info::platform::version>();
+  const bool HasOpenCL = (platformVersion.find("OpenCL") != std::string::npos);
+  const bool HasCUDA = (platformVersion.find("CUDA") != std::string::npos);
 
-  backend *BackendPref = detail::SYCLConfig<detail::SYCL_BE>::get();
-  auto BackendType = detail::getSyclObjImpl(Device)->getPlugin().getBackend();
-  static_assert(std::is_same<backend, decltype(BackendType)>(),
-                "Type is not the same");
+  backend *PrefBackend = detail::SYCLConfig<detail::SYCL_BE>::get();
+  auto DeviceBackend = detail::getSyclObjImpl(Device)->getPlugin().getBackend();
 
-  // If no preference, assume OpenCL and reject CUDA backend
-  if (BackendType == backend::cuda && !BackendPref) {
+  // Reject the NVIDIA OpenCL implementation
+  if (DeviceBackend == backend::opencl && HasCUDA && HasOpenCL)
     return true;
-  } else if (!BackendPref)
-    return false;
 
-  // If using PI_CUDA, don't accept a non-CUDA device
-  if (BackendType == backend::opencl && *BackendPref == backend::cuda)
+  // If no preference, assume OpenCL and reject CUDA
+  if (DeviceBackend == backend::cuda && !PrefBackend) {
     return true;
+  } else if (!PrefBackend)
+    return false;
 
-  // If using PI_OPENCL, don't accept a non-OpenCL device
-  if (BackendType == backend::cuda && *BackendPref == backend::opencl)
+  // If using PI_OPENCL, reject the CUDA backend
+  if (DeviceBackend == backend::cuda && *PrefBackend == backend::opencl)
     return true;
 
   return false;

sycl/source/device_selector.cpp

@@ -34,21 +34,6 @@ device device_selector::select_device() const {
   int score = -1;
   const device *res = nullptr;
   for (const auto &dev : devices) {
-
-    // Reject the NVIDIA OpenCL platform
-    if (!dev.is_host()) {
-      string_class PlatformName = dev.get_info<info::device::platform>()
-                                      .get_info<info::platform::name>();
-      const bool IsCUDAPlatform =
-          PlatformName.find("CUDA") != std::string::npos;
-
-      if (detail::getSyclObjImpl(dev)->getPlugin().getBackend() ==
-              backend::opencl &&
-          IsCUDAPlatform) {
-        continue;
-      }
-    }
-
     int dev_score = (*this)(dev);
     if (detail::pi::trace(detail::pi::TraceLevel::PI_TRACE_ALL)) {
       string_class PlatformVersion = dev.get_info<info::device::platform>()
@@ -95,9 +80,7 @@ device device_selector::select_device() const {
 }
 
 int default_selector::operator()(const device &dev) const {
-
   int Score = -1;
-
   // Give preference to device of SYCL BE.
   if (isDeviceOfPreferredSyclBe(dev))
     Score = 50;
@@ -120,12 +103,11 @@ int default_selector::operator()(const device &dev) const {
 
 int gpu_selector::operator()(const device &dev) const {
   int Score = -1;
-
   if (dev.is_gpu()) {
     Score = 1000;
     // Give preference to device of SYCL BE.
     if (isDeviceOfPreferredSyclBe(dev))
-      Score = 50;
+      Score += 50;
   }
   return Score;
 }