Proc. SPIE. 5683, Embedded Processors for Multimedia and Communications II
KEYWORDS: Digital signal processing, Detection and tracking algorithms, Computer programming, Signal processing, Multimedia, Electronics engineering, Algorithm development, Electronic imaging, Cerium, Information science
Register allocation is an important part of optimizing compiler. The algorithm of register allocation via graph coloring is implemented by Chaitin and his colleagues firstly and improved by Briggs and others. By abstracting register allocation to graph coloring, the allocation process is simplified. As the physical register number is limited, coloring of the interference graph can’t succeed for every node. The uncolored nodes must be spilled. There is an assumption that almost all the allocation method obeys: when a register is allocated to a variable v, it can’t be used by others before v quit even if v is not used for a long time. This may causes a waste of register resource. The authors relax this restriction under certain conditions and make some improvement. In this method, one register can be mapped to two or more interfered “living” live ranges at the same time if they satisfy some requirements. An operation named merge is defined which can arrange two interfered nodes occupy the same register with some cost. Thus, the resource of register can be used more effectively and the cost of memory access can be reduced greatly.
RISC and DSP, two main architectures, have their own features. The main idea of RISC is “simple is fast”. Acting as controller, RISC is based on Load/Store structure, register-register Instruction Set Architecture (ISA), general purpose registers and cache. On the other hand, designed for signal processing, DSP emphasizes large data accessing and fast computing. It’s based on register-memory ISA, diverse addressing modes, data address generator, multiplier accumulator and RAM. As Embedded Systems grow fast, no single core architecture, neither RISC nor DSP, could meet the needs anymore. Combination is necessary. There are two kinds of combination: dual-core or single core. Single core means RISC core and DSP core melt into one core with common resource and unified ISA. A 32b media processor named MediaDSP3201 (MD32 for short) is a new member of this family. In this paper, the MD32 design is introduced and concentrated on ISA design and pipeline design. They are important in architecture design. Compatibility runs through the whole design. The ISA should include features from both RISC ISA and DSP ISA. The pipeline should fit the designed ISA as good as possible. MD32 was made by TSMC at the first try on 2004 spring. Application programs running on it show that the design is successfully and the chip is suitable for Embedded System applications.