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This is a prelude to a more elaborate work which will implement `-dead_strip` flag - garbage collection of unreachable atoms. Here, when sorting sections, we also check that the section is actually populated with some atoms, and if not, we exclude it from the final linked image. This can happen when we do not import any symbols from dynamic libraries in which case we will not be populating the stubs sections or the GOT table, implying we can skip allocating those sections. Furthermore, we also make a check that a segment is actually occupied too, with the exception of `__TEXT` segment which is non-optional given that it wraps the header and load commands and thus is required by the `dyld` to perform dynamic linking, and `__PAGEZERO` which is generally non-optional when the linked image is an executable. For any other segment, if its section count is zero, we mark it as dead and skip allocating it and generating a load command for it. This commit also includes some minor improvements to the linker such as refactoring of the segment allocating codepaths, skipping `__PAGEZERO` generation for dylibs, and skipping generation of zero-sized atoms for special symbols such as `__mh_execute_header` and `___dso_handle`. These special symbols are only allocated local and global symbol pair and their VM addresses is set to the start of the `__TEXT` segment, but no `Atom` is created, as it's not necessary given that they never carry any machine code. Finally, we now always force-link against `libSystem` which turns out to be required for `dyld` to properly handle `LC_MAIN` load command on older macOS versions such as 10.15.7.
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.