support cpu/xpu/gpu in static graph (#460)

tools/static/train.py

@@ -63,15 +63,18 @@ def main(args):
 
     config = get_config(args.config, overrides=args.override, show=True)
     # assign the place
-    use_gpu = config.get("use_gpu", True)
+    use_gpu = config.get("use_gpu", False)
     use_xpu = config.get("use_xpu", False)
-    assert (use_gpu or use_xpu
-            ) is True, "gpu or xpu must be true in static mode!"
     assert (
         use_gpu and use_xpu
     ) is not True, "gpu and xpu can not be true in the same time in static mode!"
 
-    place = paddle.set_device('gpu' if use_gpu else 'xpu')
+    if use_gpu:
+        place = paddle.set_device('gpu')
+    elif use_xpu:
+        place = paddle.set_device('xpu')
+    else:
+        place = paddle.set_device('cpu')
 
     # startup_prog is used to do some parameter init work,
     # and train prog is used to hold the network