Modify the DataType directly when the Operand of whileOp is FakeFull.

[zhanghonggeng]

PR Category

Performance Optimization

PR Types

Performance

Description

while op会创建一个fake的full op，如下所示：
(%2678) = "pd_op.full" [id:743] () {dtype:(pd_op.DataType)float16,persistable:[false],place:(pd_op.Place)Place(undefined:0),shape:(pd_op.IntArray)[],stop_gradient:[false],sym_shape_str:"shape[], data[0]",value:(Float)0} : () -> builtin.tensor<-1x501x4xf16>
其中属性shape和输出tensor的dims信息对不上。while op不支持低精度计算，AMP会将fakle full op后插入cast将其从fp16转为fp32，而CINN会将full和cast OP组成cinn_op.group。由于CINN不支持fake full op的处理，因此不期望在fake op后插cast，而是直接修改full op的数据类型。
Pcard-67164

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