Modern compilers apply aggressive optimisation techniques that can make resulting programs significantly faster than naïvely generated machine code. However, these optimisations remain largely unknown to the average programmer. A lack of proper exposure to the topic (combined with the perceived complexity of many techniques) has led to the widespread belief that compilers perform "Black Magic."
This talk aims to dispel that notion by offering a practical introduction to compiler optimisations, with a scope limited to the C programming language and its associated compilers. Attendees will gain insight into why optimisations matter, how they operate at different stages of compilation, and how code structure can either facilitate or obstruct these transformations.
Agenda
Why optimise
Simple optimisations
Complex optimisations
Loop-related transformations
Practical takeaways
Optimisations are powerful but structure-dependent
Code shape can enable or inhibit performance
Understanding compilers leads to better code