Lookup copy agent when blit is selected.

Disallow passing agent 0 to avoid any API change.

Change-Id: I704fb2e04cec50500fac41a405c8a7e83a3c9fb5

runtime/hsa-runtime/core/runtime/runtime.cpp

@@ -469,25 +469,24 @@ hsa_status_t Runtime::CopyMemory(void* dst, core::Agent* dst_agent, const void*
                                  core::Agent* src_agent, size_t size,
                                  std::vector<core::Signal*>& dep_signals,
                                  core::Signal& completion_signal) {
-
   auto lookupAgent = [this](core::Agent* agent, const void* ptr) {
-    if (agent == nullptr || flag().discover_copy_agents()) {
-      hsa_amd_pointer_info_t info;
-      PtrInfoBlockData block;
-      info.size = sizeof(info);
-      PtrInfo(ptr, &info, nullptr, nullptr, nullptr, &block);
-      // Limit to IPC and GFX types for now.  These are the only types for which the application may
-      // not posess a proper agent handle.
-      if ((info.type != HSA_EXT_POINTER_TYPE_IPC) && (info.type != HSA_EXT_POINTER_TYPE_GRAPHICS)) {
-        return agent;
-      }
-      return block.agentOwner;
+    hsa_amd_pointer_info_t info;
+    PtrInfoBlockData block;
+    info.size = sizeof(info);
+    PtrInfo(ptr, &info, nullptr, nullptr, nullptr, &block);
+    // Limit to IPC and GFX types for now.  These are the only types for which the application may
+    // not posess a proper agent handle.
+    if ((info.type != HSA_EXT_POINTER_TYPE_IPC) && (info.type != HSA_EXT_POINTER_TYPE_GRAPHICS)) {
+      return agent;
     }
-    return agent;
+    return block.agentOwner;
   };
 
-  dst_agent = lookupAgent(dst_agent, dst);
-  src_agent = lookupAgent(src_agent, src);
+  // Lookup owning agent if blit kernel is selected or if flag override is set.
+  if ((dst_agent == src_agent) || flag().discover_copy_agents()) {
+    dst_agent = lookupAgent(dst_agent, dst);
+    src_agent = lookupAgent(src_agent, src);
+  }
   if (dst_agent == nullptr || src_agent == nullptr) return HSA_STATUS_ERROR_INVALID_AGENT;
 
   // At least one agent must be available for operation in the current process.