Indirect jumps improve instruction sequence performance

TL;DR

This paper demonstrates that replacing indirect jumps with direct jumps in instruction sequences can lead to unbounded increases in internal delays if the sequence length is not limited, highlighting a trade-off in instruction sequence optimization.

Contribution

It provides a formal analysis showing the impact of eliminating indirect jumps on internal delays and sequence length in unbounded instruction sequences.

Findings

Elimination of indirect jumps can cause unbounded internal delays.

The increase in internal delays is not linearly bounded when removing indirect jumps.

Trade-offs exist between instruction sequence length and execution delay.

Abstract

Instruction sequences with direct and indirect jump instructions are as expressive as instruction sequences with direct jump instructions only. We show that, in the case where the number of instructions is not bounded, we are faced with increases of the maximal internal delays of instruction sequences on execution that are not bounded by a linear function if we strive for acceptable increases of the lengths of instruction sequences on elimination of indirect jump instructions.