[Relay][Compilation] replace relay.build_module with C++ BuildModule (apache#3174)

Author: zhiics

python/tvm/relay/__init__.py

@@ -25,7 +25,7 @@
 from . import module
 from . import adt
 from . import ir_pass
-from .build_module import build, build_config, create_executor, optimize
+from .build_module import build, build_config, create_executor
 from . import prelude
 from . import parser
 from . import debug

python/tvm/relay/_build_module.py

@@ -0,0 +1,21 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# pylint: disable=no-else-return, unidiomatic-typecheck, undefined-variable
+"""The interface for building Relay functions exposed from C++."""
+from tvm._ffi.function import _init_api
+
+_init_api("relay.build_module", __name__)

python/tvm/relay/backend/graph_runtime_codegen.py

@@ -36,12 +36,9 @@
 from __future__ import absolute_import
 
 from tvm.ndarray import empty
-from tvm._ffi.function import _init_api
-
 from tvm.relay import build_module
 from tvm import target as _target
-
-_init_api("tvm.relay.build_module")
+from tvm import expr as _expr
 
 class GraphRuntimeCodegen(object):
     """The compiler from Relay to the TVM runtime system."""
@@ -57,17 +54,14 @@ def __init__(self, mod, target):
         self._setup(mod, target)
 
     def _setup(self, mod, target):
-        tgts = []
+        tgts = {}
         if isinstance(target, dict):
-            for kv in target.items():
-                tgts.append(kv[0])
-                if isinstance(kv[1], (str, _target.Target)):
-                    tgts.append(str(kv[1]))
-                else:
+            for dev, tgt in target.items():
+                if not isinstance(tgt, (str, _target.Target)):
                     raise Exception("Unknown target type")
+                tgts[dev] = _target.create(tgt)
         elif isinstance(target, (str, _target.Target)):
-            tgts.append("0")
-            tgts.append(str(target))
+            tgts[_expr.IntImm("int32", 0)] = _target.create(target)
         self._init(mod, tgts)
 
     def codegen(self, func):