Compile-time type information should be valuable in efficient compilation of statically typed functional languages such as Standard ML. But how should type-directed compilation work in real compilers, and how much performance gain will type-based optimizations yield? In order to support more efficient data representations and gain more experience about type-directed compilation, we have implemented a new type-based middle end and back end for the Standard ML of New Jersey compiler. We describe the basic design of the new compiler, identify a number of practical issues, and then compare the performance of our new compiler with the old non-type-based compiler. Our measurement shows that a combination of several simple type-based optimizations reduces heap allocation by 36%; and improves the already-efficient code generated by the old non-type-based compiler by about 19% on a DECstation 5000.

This technical report has been published as

A Type-Based Compiler for Standard ML. Zhong Shao and Andrew W. Appel, Proc. 1995 ACM Conf. on Programming Language Design and Implementation, (ACM SIGPLAN Notices vol. 30, number 6), pp. 116-129, June 1995.