A Novel Chaining Approach for Direct Control Transfer Instructions

Software-based code cache systems are the key element in the dynamic translation system or optimization system to store the translated or optimized code for reuse. Translated code is organized in terms of code blocks in the code cache which transfers execution to the next code block through a control transfer instruction. As the target address of the control transfer instruction is in the form of its source program counter, the code cache system has to check the address mapping table for the translated program counter of the target address before entering the required code block. This will cause the performance degradation. As the target address of the direct control transfer instruction is fixed during the execution of a program, its source target address can be replaced with the translated target address. A direct control transfer chaining approach which occupies specific software assists is proposed in this paper. Evaluation of DCTC is conducted on a code cache simulator. The experiment results show the dramatic performance improvement brought by DCTC.