[dy2static] Parameter Recorder Part 2: new parameter collection mechanism

[2742195759]

PR types

Function optimization

PR changes

Others

Describe

Dy2static new parameter collection mechanism !!

1. support global tensor used by function decorated by to_static.
2. support self.xxx: tensor used by function decorated by to_static.
3. support deepxde model.
   

Limitation:

目前还不支持 set attribute ，所以不要有如下行为：

@to_static
g = paddle.to_tensor(1.0)
def func(x):
    global g
    g = 2 * g # 不支持，因为 2 * g 是一个 variable，所以这里导致全局的g被替换为了 varaible，影响下一次执行。

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[0x45f]

LGTM