Introduction

Authors: Domen Verber, Jani Dugonik

Instruction-Level Parallelism (ILP) represents one of the most significant advances in computer architecture, fundamentally changing how we approach processor design and performance optimisation. At its essence, ILP enables processors to execute multiple instructions simultaneously, but this simple description belies the sophisticated mechanisms and careful engineering required to implement it effectively.

To understand the significance of ILP, we must first consider how processors traditionally executed instructions. In early computer designs, instructions were processed strictly one after another, creating a sequential bottleneck that limited performance. ILP broke through this limitation by recognising that many program instructions are independent of each other and could be executed simultaneously if the hardware supported it. This insight led to a revolution in processor design, spawning numerous innovations that continue to influence computing today.

The impact of ILP extends far beyond mere performance improvements. It represents a fundamental shift in how we think about program execution, requiring close cooperation between hardware design and software optimisation. This symbiotic relationship between hardware and software has driven innovations in both fields, from sophisticated compiler optimisations to complex processor architectures.