Static IO Analysis In DFT/ADG Software

Automatic Differentiation (AD) is a set of techniques based on the mechanical application of the chain rule to obtain derivatives of a function given as a computer program. Compared to finite differencing method, AD can calculate gradients and Hessian matrix in a much faster way without truncation error. For example, the adjoint model can calculate gradients with the time cost only several times of the underlying function and independent of the number of the independent variables. In recent years, Automatic differentiation tools, including the DFT/ADG software, are widely used to obtain differentiation models.Currently, the forward model generators show a lot of maturity in validation an efficiency, while almost all of the reverse model generators (espically the adjoint model generators) still have a long way to go. That's why the code evaluation system, which can evaluate the two models in time cost, memory cost and reliability by statistics method, plays a key role in AD software. As the upper and input layer of the code evaluation system, the static IO analysis is also an undisplacable part. In the past, the instability of the IO analysis in DFT/ADG software resulted in a lot of hand-on work. In this paper, we mean to analyze the need on the basic of the current system, and rebuild a stable IO analysis module of the DFT/ADG software, which can offer a more precise IO result to the generation of the testing code. The work include the following parts:1. Summarize the functionality of the current version of DFT/ADG, find the defect of the code evaluation system, and tell the importance of the IO analysis;2. Find a right position of the new module by analyzing how the system runs;3. Overall data flow design and detailed algorithm design. And I am going to present some boundary conditions which are brought up mainly by the defect of the interface.4. Do optimization for XIAMEN software. Make optimization plan by analyzing the underlying function. Finally, point out the difficulties in the application, and try to give out general methods in solving the problems.5. Finally, a lot of tests have been done to prove the efficiency of DFT/ADG software, the validation of the IO analysis, and the performance by using AD.