[SYCL] Add Plugin Interface (PI) layer. (#222)

This might look like a lot of changes but the vast majority of it is just renaming and moving (due to file renaming). The key points are:
- PI level (pi* files) replaces CNRI (cnri* files), with true but yet naive plugin mechanism
- New naming conventions are introduced for PI
- Directly calling OpenCL is still the default path until everything switches to PI
- The platform class implementation is refactored - host and device implementations are merged into single file

Signed-off-by: Sergey V Maslov <[email protected]>

Author: smaslov-intel

sycl/CMakeLists.txt

@@ -123,9 +123,11 @@ set(LLVM_TOOLS_DIR "${LLVM_BINARY_DIR}/bin/")
 add_library("${SYCLLibrary}" SHARED
   "${includeRootPath}/CL/sycl.hpp"
   "${sourceRootPath}/detail/builtins.cpp"
-  "${sourceRootPath}/detail/cnri.cpp"
+  "${sourceRootPath}/detail/pi.cpp"
+  "${sourceRootPath}/detail/pi_opencl.cpp"
   "${sourceRootPath}/detail/common.cpp"
   "${sourceRootPath}/detail/context_impl.cpp"
+  "${sourceRootPath}/detail/device_impl.cpp"
   "${sourceRootPath}/detail/device_info.cpp"
   "${sourceRootPath}/detail/event_impl.cpp"
   "${sourceRootPath}/detail/force_device.cpp"
@@ -134,8 +136,7 @@ add_library("${SYCLLibrary}" SHARED
   "${sourceRootPath}/detail/kernel_impl.cpp"
   "${sourceRootPath}/detail/kernel_info.cpp"
   "${sourceRootPath}/detail/memory_manager.cpp"
-  "${sourceRootPath}/detail/platform_host.cpp"
-  "${sourceRootPath}/detail/platform_opencl.cpp"
+  "${sourceRootPath}/detail/platform_impl.cpp"
   "${sourceRootPath}/detail/platform_info.cpp"
   "${sourceRootPath}/detail/program_impl.cpp"
   "${sourceRootPath}/detail/program_manager/program_manager.cpp"

sycl/include/CL/sycl/detail/aligned_allocator.hpp

@@ -9,7 +9,7 @@
 #pragma once
 
 #include <CL/cl.h>
-#include <CL/sycl/detail/cnri.h>
+#include <CL/sycl/detail/common.hpp>
 #include <CL/sycl/detail/os_util.hpp>
 #include <CL/sycl/range.hpp>
 

sycl/include/CL/sycl/detail/cnri.h

@@ -15,9 +15,22 @@
 #include <CL/cl_ext.h>
 #include <CL/cl_ext_intel.h>
 #include <string>
-
 #include <type_traits>
 
+// Select underlying runtime interface in compile-time (OpenCL or PI).
+// Comment the define of the FORCE_SYCL_BE_OPENCL below to switch to PI.
+// As such only one path (OpenCL today) is being regularily tested.
+//
+// TODO: we can just remove this when switch to PI completely.
+//
+#define FORCE_SYCL_BE_OPENCL
+
+#ifdef FORCE_SYCL_BE_OPENCL
+#include <CL/sycl/detail/pi_opencl.hpp>
+#else
+#include <CL/sycl/detail/pi.hpp>
+#endif
+
 const char *stringifyErrorCode(cl_int error);
 
 #define OCL_CODE_TO_STR(code)                                                  \
@@ -78,6 +91,16 @@ const char *stringifyErrorCode(cl_int error);
 namespace cl {
 namespace sycl {
 namespace detail {
+
+// Select underlying runtime interface (RT) in compile-time (OpenCL or PI).
+// As such only one path (OpenCL today) is being regularily tested.
+//
+#ifdef FORCE_SYCL_BE_OPENCL
+using RT = cl::sycl::detail::opencl;
+#else
+using RT = cl::sycl::detail::pi;
+#endif
+
 // Helper function for extracting implementation from SYCL's interface objects.
 // Note! This function relies on the fact that all SYCL interface classes
 // contain "impl" field that points to implementation object. "impl" field