Using higher-order control flow analysis when compiling functional languages

Abstract

Runtime type tests elimination and closures optimizations speed up executable programs produced by the compiler. The more higher-order programs are, the more impressive the gains will be obtained. For instance, we measured a 20 % speed-up for programs implementing denotational semantics or, more generally, for programs intensively using curried functions. On the other hand, the Ocfa analysis has a very high complexity: in the worst case, it is O(n ³). One could expect that the addition of this analysis may slow down the compiler in a drastic way. This is not true: the Ocfa analysis is almost linear for usual programs. As an experimental proof, a complete bootstrap of the Bigloo compiler (40.000 lines of Scheme code) is only 25 % slower when the Ocfa analysis is enabled.