407dc6eee4
Backends want to avoid emitting unused instructions which do not have side effects: to that end, they all have `Liveness.isUnused` checks for many instructions. However, checking this in the backends avoids a lot of potential optimizations. For instance, if a nested field is loaded, then the first field access would still be emitted, since its result is used by the next access (which is then unreferenced). To elide more instructions, Liveness can track this data instead. For operands which do not have to be lowered (i.e. are not side effecting and are not something special like `arg), Liveness can ignore their operand usages, and push the unused information further up, potentially marking many more instructions as unreferenced. In doing this, I also uncovered a bug in the LLVM backend relating to discarding the result of `@cVaArg`, which this change fixes. A behaviour test has been added to cover it.
A general-purpose programming language and toolchain for maintaining robust, optimal, and reusable software.
Resources
- Introduction
- Download & Documentation
- Chapter 0 - Getting Started | ZigLearn.org
- Community
- Contributing
- Code of Conduct
- Frequently Asked Questions
- Community Projects
Installation
- download a pre-built binary
- install from a package manager
- build from source
- bootstrap zig for any target
License
The ultimate goal of the Zig project is to serve users. As a first-order effect, this means users of the compiler, helping programmers to write better software. Even more important, however, are the end-users.
Zig is intended to be used to help end-users accomplish their goals. Zig should be used to empower end-users, never to exploit them financially, or to limit their freedom to interact with hardware or software in any way.
However, such problems are best solved with social norms, not with software licenses. Any attempt to complicate the software license of Zig would risk compromising the value Zig provides.
Therefore, Zig is available under the MIT (Expat) License, and comes with a humble request: use it to make software better serve the needs of end-users.
This project redistributes code from other projects, some of which have other licenses besides MIT. Such licenses are generally similar to the MIT license for practical purposes. See the subdirectories and files inside lib/ for more details.