[RELAY] Inline scalar compute (#2335)

src/relay/backend/compile_engine.cc

@@ -84,6 +84,9 @@ class ScheduleGetter :
     CHECK(master_op_.defined());
     Schedule schedule = fschedule[master_op_](
         master_attrs_, cache_node->outputs, target_);
+    for (const auto& scalar : scalars_) {
+      schedule[scalar].compute_inline();
+    }
     return std::make_pair(schedule, cfunc);
   }
 
@@ -123,6 +126,7 @@ class ScheduleGetter :
           return tvm::Expr();
         }
       });
+    scalars_.push_back(value->op);
     return {value};
   }
 
@@ -216,6 +220,7 @@ class ScheduleGetter :
   int master_op_pattern_{0};
   std::ostringstream readable_name_stream_;
   std::unordered_map<Expr, Array<Tensor>, NodeHash, NodeEqual> memo_;
+  Array<Operation> scalars_;
 };