| Research Abstract |
Almost all the programs are developed by help of general purpose computer languages and their compilers, now. The ordinary compilers usually generate program codes with strictly following the computational order written in the source programs. These compilers can generate efficient codes for ordinary computers and microprocessors, but, for the recent processors like digital signal processors (DSPs), codes generated under the same compiler techniques include many overhead generate highly efficient codes by computational codes, because of multiple arithmetic operation units or multi-stages pipeline in these processors. Therefore, the goal of this project is to realize a completely new compiler system for general purpose languages, which can generate highly efficient codes.
C language is employed for a general purpose language in this project, because it is widely accepted. A given source program written in C can be represented by a flow graph with precedence relation between variables. In the flow graph, fork and conjunction nodes are introduced with conditional/non-conditional branches and loops in a program. By these nodes, the flow graph is partitioned into several primitive blocks. For each primitive block, an order with less overhead codes is derived by a scheduling algorithm under the precedence relation. In order to reduce overhead codes due to branch instructions, a method to moe codes between primitive blocks is proposed.
The proposed alogorithms are applied to the C compiler for TMS320C30 (TI) and muPD77230 (NEC). By codes generated by this compiler for several examples with conditional branches and loops, the proposed methods are proved to be effective.
On the otherhand, in order to derive a highly efficient DSP codes, not only optimization in computational ordering but also that in memory access is very important. In this project, optimization methods for DSP memory addressing are also investigated.
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