Bulldog

Bulldog demonstrates that a symbiosis of a new Very Long Instruction Word (VLIW) architectures and new compiling technology is practicable. VLIW architectures are reduced-instruction-set machines with a large number of parallel, pipelined functional unites but only a single thread of control. These machines offer the promise of an immediate order-of-magnitude increase in speed for general purpose scientific computing. However, a traditional compiler can't find enough parallelism in scientific programs to utilize a VLIW effectively. The Bulldog compiler described here uses several new compilation techniques: trace scheduling to find more parallelism, memory-reference and memory-bank disambiguation to increase memory bandwidth, and new code-generation algorithms. Although originally developed for VLIWs, many of the ideas in Bulldog could be applied to pipelined reduced-instruction-set architectures such as the MIPS. Ellis's experiments indicate that speed improvements of thirty to eighty percent are possible for scientific code on such machines. John R. Ellis received his doctorate from Yale University and is currently Principal Software Engineer, Digital Equipment Corporation Systems Research Center, Palo Alto. Bulldog: A Compiler for VLIW Architectures is winner of the 1985 ACM Doctoral Dissertation Award.