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While the SysV ABI is not that complicated, LLVM does not allow us
direct access to enforce it. By mimicking the IR generated by clang,
we can trick LLVM into doing the right thing. This involves two main
additions:
1. `AGG` ABI class
This is not part of the spec, but since we have to track class per
eightbyte and not per struct, the current enum is not enough. I
considered adding multiple classes like: `INTEGER_INTEGER`,
`INTEGER_SSE`, `SSE_INTEGER`. However, all of those cases would trigger
the same code path so it's simpler to collapse into one. This class is
only used on SysV.
2. LLVM C ABI type
Clang uses different types in C ABI function signatures than the
original structs passed in, and does conversion. For example, this
struct: `{ i8, i8, float }` would use `{ i16, float }` at ABI boundaries.
When passed as an argument, it is instead split into two arguments `i16`
and `float`. Therefore, for every struct that passes ABI boundaries we
need to keep track of its corresponding ABI type. Here are some more
examples:
```
| Struct | ABI equivalent |
| { i8, i8, i8, i8 } | i32 |
| { float, float } | double |
| { float, i32, i8 } | { float, i64 } |
```
Then, we must update function calls, returns, parameter lists and inits
to properly convert back and forth as needed.
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.