Study And Implementation On High-level Loop Transformations Technology

High-level loop transformations is a program optimization mechanism that changes the (sequential) execution order of the statement instances without changing the set of statement instances that based on high-level representations of a program. High-level loop transformations can improve the spatial and temporal locality of a program by transforming loops which possesses of poor locality under the condition that assuring the correct semantics of transformed program. So it is a paramount optimization mechanism and is used to exploit the good performance of memory hierarchies entirely.The thesis studies the main factors that affect the high-level loop transformations during implementation. Then, it analyzes the principle and implementation framework of linear loop transformations in GCC, which supports multiple programming languages. Last but not least, the thesis implements a few algorithms in GCC to improve linear loop transformations.Primary innovative work in this paper can be summarized as following:1) The thesis studies the main factors that affect the high-level loop transformations from the point of view of implementations.2) The thesis studies the factors affecting loop transformations which are brought by linearized array reference subscripts in FORTRAN programs, and develops an algorithm to recover multi-dimension array reference subscripts of linearized FORTRAN array reference subscripts.3) By thoroughly studying and analyzing the linear loop transformations infrastructure of GCC, the thesis improves its implementations. Our work improves the performance of benchmark in SPECfp2000 and other scientific and simulative programs.