added transpiler pass for mkldnn depthwise_conv

test=develop

python/paddle/fluid/transpiler/inference_transpiler.py

@@ -61,6 +61,9 @@ class InferenceTranspiler(object):
             raise TypeError("scope should be as Scope type or None")
         use_mkldnn = bool(os.getenv("FLAGS_use_mkldnn", False))
 
+        if use_mkldnn:
+            self._depthwise_conv_mkldnn(program)
+
         self._fuse_batch_norm(program, place, scope)
         if use_mkldnn:
             self._fuse_conv_bias_mkldnn(program)
@@ -70,6 +73,31 @@ class InferenceTranspiler(object):
                 program)  # ResNet residual block merging
             self._fuse_bn_relu_mkldnn(program)
 
+    def _depthwise_conv_mkldnn(self, program):
+        '''
+        Transpile the program by replacing depthwise_conv2d to conv2d for MKLDNN program.
+        The result is:
+            - before:
+                - any_other_op->depthwise_conv->any_other_op
+            - after:
+                - any_other_op->conv->any_other_op
+        :param program: program to transpile
+        :type program: Program
+        '''
+        self.block = program.block(0)
+
+        i = 0
+        while i < len(self.block.ops):
+            current_op = self.block.ops[i]
+            if current_op.type == 'depthwise_conv2d':
+                current_op.desc.set_type("conv2d")
+            i = i + 1
+
+        # TODO(luotao): use clone() method to flush the program.desc in force,
+        # since some large program.desc will not be flushed immediately.
+        # And a better solution will be considered later.
+        program = program.clone()
+
     def _fuse_conv_eltwise_mkldnn(self, program):
         '''
         Transpile the program fusing elementwise_add into conv for MKLDNN