Introduce the concept of sycl backends into dpctl.

   -- Queues now need to be queried using both backend and device type.
   -- Fix test cases.
   -- Platform interfaces now can return the list of available backends.
   -- Fix skiped tests.
   -- Expand the platform interface to provide backend info.
   -- Move backend enums to platfrom from context.
   -- Add comments.
   -- Store opencl_cpu, opencl_gpu, and level0_gpu queues inside queue manager.
   -- Fixed enum typedefs, added cython dict to store backends and device types.

Author: diptorupd

backends/include/dppl_sycl_context_interface.h

@@ -27,26 +27,14 @@
 
 #include "dppl_data_types.h"
 #include "dppl_sycl_types.h"
+#include "dppl_sycl_platform_interface.h"
 #include "Support/DllExport.h"
 #include "Support/ExternC.h"
 #include "Support/MemOwnershipAttrs.h"
 #include <stdbool.h>
 
 DPPL_C_EXTERN_C_BEGIN
 
-/*!
- * @brief Redefinition of DPC++'s backend types. We have this wrapper so that
- * the sycl header is not exposed to Python extensions.
- *
- */
-typedef enum
-{
-    DPPL_OPENCL     = 1 << 16,
-    DPPL_HOST       = 1 << 15,
-    DPPL_LEVEL_ZERO = 1 << 14,
-    DPPL_CUDA       = 1 << 13
-} DPPLSyclBEType;
-
 /*!
  * @brief Returns true if this SYCL context is a host context.
  *
@@ -63,7 +51,7 @@ bool DPPLContext_IsHost (__dppl_keep const DPPLSyclContextRef CtxRef);
  * @return   {return}       My Param doc
  */
 DPPL_API
-DPPLSyclBackendType
+DPPLSyclBEType
 DPPLContext_GetBackend (__dppl_keep const DPPLSyclContextRef CtxRef);
 
 /*!

backends/include/dppl_sycl_device_interface.h

@@ -40,18 +40,18 @@ DPPL_C_EXTERN_C_BEGIN
  * sycl.hpp here and in the Python bindings.
  *
  */
-typedef enum
+enum DPPLSyclDeviceType
 {
     DPPL_CPU         = 1 << 0,
     DPPL_GPU         = 1 << 1,
     DPPL_ACCELERATOR = 1 << 2,
     DPPL_CUSTOM      = 1 << 3,
     DPPL_AUTOMATIC   = 1 << 4,
-    DPPL_HOST        = 1 << 5,
+    DPPL_HOST_DEVICE = 1 << 5,
     DPPL_ALL         = 1 << 6
     // IMP: before adding new values here look at DPPLSyclBEType enum. The
     // values should not overlap.
-} DPPLSyclDeviceType;
+};
 
 /*!
  * @brief Prints out some of the info::deivice attributes for the device.

backends/include/dppl_sycl_platform_interface.h

@@ -28,17 +28,57 @@
 #include "dppl_data_types.h"
 #include "Support/DllExport.h"
 #include "Support/ExternC.h"
+#include "Support/MemOwnershipAttrs.h"
 
 DPPL_C_EXTERN_C_BEGIN
 
 /*!
- * @brief Get the number of sycl::platform available on the system.
+ * @brief Redefinition of DPC++'s backend types. We have this wrapper so that
+ * the sycl header is not exposed to Python extensions.
+ *
+ */
+enum DPPLSyclBEType
+{
+    DPPL_UNKNOWN_BACKEND = 0x0,
+    DPPL_OPENCL          = 1 << 16,
+    DPPL_HOST            = 1 << 15,
+    DPPL_LEVEL_ZERO      = 1 << 14,
+    DPPL_CUDA            = 1 << 13
+};
+
+/*!
+ * @brief Returns the number of sycl::platform available on the system.
  *
  * @return The number of available sycl::platforms.
  */
 DPPL_API
 size_t DPPLPlatform_GetNumPlatforms ();
 
+/*!
+ * @brief Returns the number of unique sycl backends on the system not counting
+ * the host backend.
+ *
+ * @return   The number of unique sycl backends.
+ */
+DPPL_API
+size_t DPPLPlatform_GetNumBackends ();
+
+/*!
+ * @brief Returns an array of the unique DPPLSyclBEType values on the system.
+ *
+ * @return   An array of DPPLSyclBEType enum values.
+ */
+DPPL_API
+__dppl_give enum DPPLSyclBEType* DPPLPlatform_GetListOfBackends ();
+
+/*!
+ * @brief Frees an array of DPPLSyclBEType enum values.
+ *
+ * @param    BEArr          An array of DPPLSyclBEType enum values to be freed.
+ */
+DPPL_API
+void DPPLPlatform_DeleteListOfBackends (__dppl_take enum DPPLSyclBEType* BEArr);
+
 /*!
  * @brief Prints out some selected info about all sycl::platform on the system.
  *

backends/include/dppl_sycl_queue_manager.h

@@ -64,9 +64,10 @@ __dppl_give DPPLSyclQueueRef DPPLQueueMgr_GetCurrentQueue ();
  * raised if no such device exists.
  */
 DPPL_API
-__dppl_give DPPLSyclQueueRef DPPLQueueMgr_GetQueue (DPPLSyclBEType BETy,
-                                                    DPPLSyclDeviceType DeviceTy,
-                                                    size_t DNum);
+__dppl_give DPPLSyclQueueRef
+DPPLQueueMgr_GetQueue (enum DPPLSyclBEType BETy,
+                       enum DPPLSyclDeviceType DeviceTy,
+                       size_t DNum);
 
 /*!
  * @brief Get the number of activated queues not including the global or
@@ -87,8 +88,8 @@ size_t DPPLQueueMgr_GetNumActivatedQueues ();
  * @return   The number of available queues.
  */
 DPPL_API
-size_t DPPLQueueMgr_GetNumQueues (DPPLSyclBEType BETy,
-                                  DPPLSyclDeviceType DeviceTy);
+size_t DPPLQueueMgr_GetNumQueues (enum DPPLSyclBEType BETy,
+                                  enum DPPLSyclDeviceType DeviceTy);
 
 /*!
 * @brief Set the default DPPL queue to the sycl::queue for the given backend
@@ -101,8 +102,8 @@ size_t DPPLQueueMgr_GetNumQueues (DPPLSyclBEType BETy,
 * @param    DNum           Device id for the device (defaults to 0)
 */
 DPPL_API
-void DPPLQueueMgr_SetAsDefaultQueue (DPPLSyclBEType BETy,
-                                     DPPLSyclDeviceType DeviceTy,
+void DPPLQueueMgr_SetAsDefaultQueue (enum DPPLSyclBEType BETy,
+                                     enum DPPLSyclDeviceType DeviceTy,
                                      size_t DNum);
 
 /*!
@@ -127,8 +128,8 @@ void DPPLQueueMgr_SetAsDefaultQueue (DPPLSyclBEType BETy,
  */
 DPPL_API
 __dppl_give DPPLSyclQueueRef
-DPPLQueueMgr_PushQueue (DPPLSyclBEType BETy,
-                        DPPLSyclDeviceType DeviceTy,
+DPPLQueueMgr_PushQueue (enum DPPLSyclBEType BETy,
+                        enum DPPLSyclDeviceType DeviceTy,
                         size_t DNum);
 
 /*!

backends/source/dppl_sycl_context_interface.cpp

@@ -47,7 +47,7 @@ void DPPLContext_Delete (__dppl_take DPPLSyclContextRef CtxRef)
     delete unwrap(CtxRef);
 }
 
-DPPLSyclBackendType
+DPPLSyclBEType
 DPPLContext_GetBackend (__dppl_keep const DPPLSyclContextRef CtxRef)
 {
     auto BE = unwrap(CtxRef)->get_platform().get_backend();