Add stronger checking

- Add assertions to enforce that objects are of the correct kind and
  have been allocated.

- Make destructors check if objects have been allocated before
  deleting.

- Operations that require a non-NullDevice return failure if given a
  NullDevice.

- Use static_cast rather than reinterpret_cast when cohersing from a
  base class to a derived class.

Change-Id: I02ee0ea9d7982fd7ca29d49c9b02cfae111b7127

rocclr/device/rocm/rocprogram.hpp

@@ -52,12 +52,18 @@ class Program : public device::Program {
   const NullDevice& rocNullDevice() const { return static_cast<const NullDevice&>(device()); }
 
   //! Return a typecasted GPU device
-  const Device& rocDevice() const { return static_cast<const Device&>(device()); }
+  const Device& rocDevice() const {
+    assert(!isNull());
+    return static_cast<const Device&>(device());
+  }
 
   //! Returns the hsaBinary associated with the program
   hsa_agent_t hsaDevice() const { return rocNullDevice().getBackendDevice(); }
 
-  hsa_executable_t hsaExecutable() const { return hsaExecutable_; }
+  hsa_executable_t hsaExecutable() const {
+    assert(!isNull());
+    return hsaExecutable_;
+  }
 
   virtual bool createGlobalVarObj(amd::Memory** amd_mem_obj, void** dptr,
                                   size_t* bytes, const char* globalName) const;