Chaining Span-Dependent Jump Instructions

Abstract

The assembled length of a span-dependent jump instruction depends on the distance between the instruction and its target. Such instructions are found on many computers and typically have two forms, long and short. We consider the problem of minimizing object program length for such machines by chaining together jumps with the same target. Although the problem is NP-complete in its most general form, several mildly restricted forms of the problem exist that are of practical importance and have efficient solutions.

Design of an optimizing, dynamically retargetable compiler for common Lisp

“…Thus, in general, some sort of relaxation technique is needed to arrive st optimal code. Leverett [Leverett 1980] and others have presented algorithms that optimize programs for code density by converting long jumps into short jumps to long jumps. Since we optimize for time rather than space in such cases, these algorithms were not found appropriate.…”