[SYCL] Small fixes and adjusments around sycl exceptions. (intel#539)

* Make cl::sycl::exception inherit from std::exception

If exception is not caught by user's try block in the main function
it is usually caught by default c++ handler which for exceptions
inherited from std::exception prints content returned by "what" method.

* Release program object if build fails
* Throw friendly exception command groups without operation

* Fix lit tests

Added dummy parallel_for's as command groups cannot be empty.
Removed usage of command group in GetWaitList test.

Signed-off-by: Vlad Romanov <vlad.romanov@intel.com>

Author: romanovvlad

sycl/include/CL/sycl/detail/cg.hpp

@@ -319,6 +319,7 @@ class CG {
 public:
   // Type of the command group.
   enum CGTYPE {
+    NONE,
     KERNEL,
     COPY_ACC_TO_PTR,
     COPY_PTR_TO_ACC,

sycl/include/CL/sycl/detail/program_manager/program_manager.hpp

@@ -65,7 +65,7 @@ class ProgramManager {
 private:
   RT::PiProgram loadProgram(OSModuleHandle M, const context &Context,
                             DeviceImage **I = nullptr);
-  void build(RT::PiProgram &Program, const string_class &Options = "",
+  void build(RT::PiProgram Program, const string_class &Options = "",
              std::vector<RT::PiDevice> Devices = std::vector<RT::PiDevice>());
 
   ProgramManager() = default;

sycl/include/CL/sycl/exception.hpp

@@ -13,16 +13,21 @@
 #include <CL/sycl/detail/common.hpp>
 #include <CL/sycl/stl.hpp>
 
+#include <exception>
+
 namespace cl {
 namespace sycl {
 
 // Forward declaration
 class context;
 
-struct exception {
+// Derive from std::exception so uncaught exceptions are printed in c++ default
+// exception handler.
+class exception: public std::exception {
+public:
   exception() = default;
 
-  const char *what() const noexcept;
+  const char *what() const noexcept final;
 
   bool has_context() const;
 

sycl/include/CL/sycl/handler.hpp

@@ -159,7 +159,7 @@ class handler {
   // Storage for a sycl::kernel object.
   std::shared_ptr<detail::kernel_impl> MSyclKernel;
   // Type of the command group, e.g. kernel, fill.
-  detail::CG::CGTYPE MCGType;
+  detail::CG::CGTYPE MCGType = detail::CG::NONE;
   // Pointer to the source host memory or accessor(depending on command type).
   void *MSrcPtr = nullptr;
   // Pointer to the dest host memory or accessor(depends on command type).
@@ -382,6 +382,9 @@ class handler {
           std::move(MSharedPtrStorage), std::move(MRequirements),
           std::move(MEvents)));
       break;
+    case detail::CG::NONE:
+      throw runtime_error("Command group submitted without a kernel or a "
+                          "explicit memory operation.");
     default:
       throw runtime_error("Unhandled type of command group");
     }

sycl/source/detail/program_manager/program_manager.cpp

@@ -10,12 +10,13 @@
 #include <CL/sycl/detail/common.hpp>
 #include <CL/sycl/detail/os_util.hpp>
 #include <CL/sycl/detail/program_manager/program_manager.hpp>
+#include <CL/sycl/detail/type_traits.hpp>
 #include <CL/sycl/detail/util.hpp>
 #include <CL/sycl/device.hpp>
 #include <CL/sycl/exception.hpp>
 #include <CL/sycl/stl.hpp>
 
-#include <assert.h>
+#include <cassert>
 #include <cstdlib>
 #include <fstream>
 #include <memory>
@@ -87,12 +88,19 @@ RT::PiProgram ProgramManager::getBuiltOpenCLProgram(OSModuleHandle M,
   std::shared_ptr<context_impl> Ctx = getSyclObjImpl(Context);
   std::map<OSModuleHandle, RT::PiProgram> &CachedPrograms =
       Ctx->getCachedPrograms();
-  RT::PiProgram &Program = CachedPrograms[M];
-  if (!Program) {
-    DeviceImage *Img = nullptr;
-    Program = loadProgram(M, Context, &Img);
-    build(Program, Img->BuildOptions);
-  }
+  auto It = CachedPrograms.find(M);
+  if (It != CachedPrograms.end())
+    return It->second;
+
+  DeviceImage *Img = nullptr;
+  using PiProgramT = remove_pointer_t<RT::PiProgram>;
+  unique_ptr_class<PiProgramT, decltype(RT::piProgramRelease)> ProgramManaged(
+      loadProgram(M, Context, &Img), RT::piProgramRelease);
+
+  build(ProgramManaged.get(), Img->BuildOptions);
+  RT::PiProgram Program = ProgramManaged.release();
+  CachedPrograms[M] = Program;
+
   return Program;
 }
 
@@ -150,7 +158,7 @@ string_class ProgramManager::getProgramBuildLog(const RT::PiProgram &Program) {
   return Log;
 }
 
-void ProgramManager::build(RT::PiProgram &Program, const string_class &Options,
+void ProgramManager::build(RT::PiProgram Program, const string_class &Options,
                            std::vector<RT::PiDevice> Devices) {
 
   if (DbgProgMgr > 0) {

sycl/source/detail/scheduler/commands.cpp

@@ -480,6 +480,9 @@ void ExecCGCommand::printDot(std::ostream &Stream) const {
   case detail::CG::COPY_PTR_TO_ACC:
     Stream << "CG type: copy ptr to acc\\n";
     break;
+  default:
+    Stream << "CG type: unknown\\n";
+    break;
   }
 
   Stream << "\"];" << std::endl;
@@ -692,10 +695,10 @@ cl_int ExecCGCommand::enqueueImp() {
 
     return PI_SUCCESS;
   }
+  case CG::CGTYPE::NONE:
+  default:
+    throw runtime_error("CG type not implemented.");
   }
-
-  assert(!"CG type not implemented");
-  throw runtime_error("CG type not implemented.");
 }
 
 } // namespace detail

sycl/test/basic_tests/stream.cpp

@@ -31,6 +31,8 @@ int main() {
       stream Out(1024, 80, CGH);
       assert(Out.get_size() == 1024);
       assert(Out.get_max_statement_size() == 80);
+
+      CGH.single_task<class DummyTask1>([=]() {});
     });
 
     // Check common reference semantics
@@ -47,6 +49,8 @@ int main() {
 
       assert(Out2 == Out3);
       assert(Hasher(Out2) == Hasher(Out3));
+
+      CGH.single_task<class DummyTask2>([=]() {});
     });
 
     // TODO: support cl::sycl::endl. According to specitification endl should be

sycl/test/scheduler/GetWaitList.cpp

@@ -10,16 +10,7 @@
 
 #include <CL/sycl.hpp>
 
-void foo() {
+int main() {
   cl::sycl::event start;
   start.wait_and_throw();
-  return;
-}
-
-int main() {
-  cl::sycl::queue Q;
-  Q.submit([&](cl::sycl::handler &CGH) {
-    foo();
-  });
-  return 0;
 }