Optimizer use init program (#5275)

* optimizer use init_program

* create persistable variable

* add create_persistable_var to block

* optimizer use create_persistable_var

* fix prefix

* move create_global_persistable_var from Block to LayerHelper

* Polish Optimizer initialization code.

* Using the LayerHelper to create initialize operator and variables

* add_accumulator should use an independent data type

* default use param data type for accumulator

Author: jacquesqiao

python/paddle/v2/framework/framework.py

@@ -7,6 +7,11 @@
 __all__ = ['Block', 'Variable', 'Program', 'Operator']
 
 
+def unique_name(prefix):
+    uid = core.unique_integer(prefix)  # unique during whole process.
+    return "_".join([prefix, str(uid)])
+
+
 class Variable(object):
     def __init__(self,
                  block,

python/paddle/v2/framework/layer_helper.py

@@ -1,19 +1,12 @@
 import copy
 import itertools
 
-import paddle.v2.framework.core as core
-
 from paddle.v2.framework.framework import Variable, g_program, \
-    g_init_program
+    g_init_program, unique_name, Program
 from paddle.v2.framework.initializer import ConstantInitializer, \
     UniformInitializer
 
 
-def unique_name(prefix):
-    uid = core.unique_integer(prefix)  # unique during whole process.
-    return "_".join([prefix, str(uid)])
-
-
 class LayerHelper(object):
     def __init__(self, layer_type, **kwargs):
         self.kwargs = kwargs
@@ -138,9 +131,19 @@ def create_tmp_variable(self, dtype):
     def create_variable(self, *args, **kwargs):
         return self.program.current_block().create_var(*args, **kwargs)
 
-    def create_global_variable(self, *args, **kwargs):
+    def create_global_variable(self, persistable=False, *args, **kwargs):
         return self.program.global_block().create_var(
-            *args, persistable=False, **kwargs)
+            *args, persistable=persistable, **kwargs)
+
+    def set_variable_initializer(self, var, initializer):
+        assert isinstance(var, Variable)
+        self.init_program.global_block().create_var(
+            name=var.name,
+            type=var.type,
+            dtype=var.data_type,
+            shape=var.shape,
+            persistable=True,
+            initializer=initializer)
 
     def append_bias_op(self, input_var, num_flatten_dims=None):
         """