diff --git a/.github/ISSUE_TEMPLATE/bug_report.yml b/.github/ISSUE_TEMPLATE/bug_report.yml index f754d16c7..2c1483345 100644 --- a/.github/ISSUE_TEMPLATE/bug_report.yml +++ b/.github/ISSUE_TEMPLATE/bug_report.yml @@ -6,6 +6,8 @@ body: attributes: value: > + Learn more [here](https://yosyshq.readthedocs.io/projects/yosys/en/latest/yosys_internals/extending_yosys/contributing.html#reporting-bugs) about how to report bugs. We fix well-reported bugs the fastest. + If you have a general question, please ask it on the [Discourse forum](https://yosyshq.discourse.group/). diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md index 403292b0b..6eadbec31 100644 --- a/CONTRIBUTING.md +++ b/CONTRIBUTING.md @@ -1,70 +1,63 @@ -# Introduction +# Contributing to Yosys -Thanks for thinking about contributing to the Yosys project. If this is your +Thanks for considering helping out. If this is your first time contributing to an open source project, please take a look at the -following guide: +following guide about the basics: https://opensource.guide/how-to-contribute/#orienting-yourself-to-a-new-project. -Information about the Yosys coding style is available on our Read the Docs: -https://yosys.readthedocs.io/en/latest/yosys_internals/extending_yosys/contributing.html. +## Asking questions -# Using the issue tracker - -The [issue tracker](https://github.com/YosysHQ/yosys/issues) is used for -tracking bugs or other problems with Yosys or its documentation. It is also the -place to go for requesting new features. -When [creating a new issue](https://github.com/YosysHQ/yosys/issues/new/choose), -we have a few templates available. Please make use of these! It will make it -much easier for someone to respond and help. - -### Bug reports - -Before you submit an issue, please check out the [how-to guide for -`bugpoint`](https://yosys.readthedocs.io/en/latest/using_yosys/bugpoint.html). -This guide will take you through the process of using the [`bugpoint` -command](https://yosys.readthedocs.io/en/latest/cmd/bugpoint.html) in Yosys to -produce a [minimal, complete and verifiable -example](https://stackoverflow.com/help/minimal-reproducible-example) (MVCE). -Providing an MVCE with your bug report drastically increases the likelihood that -someone will be able to help resolve your issue. - - -# Using pull requests - -If you are working on something to add to Yosys, or fix something that isn't -working quite right, make a [PR](https://github.com/YosysHQ/yosys/pulls)! An -open PR, even as a draft, tells everyone that you're working on it and they -don't have to. It can also be a useful way to solicit feedback on in-progress -changes. See below to find the best way to [ask us -questions](#asking-questions). - -In general, all changes to the code are done as a PR, with [Continuous -Integration (CI)](https://github.com/YosysHQ/yosys/actions) tools that -automatically run the full suite of tests compiling and running Yosys. Please -make use of this! If you're adding a feature: add a test! Not only does it -verify that your feature is working as expected, but it can also be a handy way -for people to see how the feature is used. If you're fixing a bug: add a test! -If you can, do this first; it's okay if the test starts off failing - you -already know there is a bug. CI also helps to make sure that your changes still -work under a range of compilers, settings, and targets. - - -### Labels - -We use [labels](https://github.com/YosysHQ/yosys/labels) to help categorise -issues and PRs. If a label seems relevant to your work, please do add it; this -also includes the labels beggining with 'status-'. The 'merge-' labels are used -by maintainers for tracking and communicating which PRs are ready and pending -merge; please do not use these labels if you are not a maintainer. - - -# Asking questions - -If you have a question about how to use Yosys, please ask on our [Discourse forum](https://yosyshq.discourse.group/) or in our [discussions -page](https://github.com/YosysHQ/yosys/discussions). +If you have a question about how to use Yosys, please ask on our [Discourse forum](https://yosyshq.discourse.group/). The Discourse is also a great place to ask questions about developing or contributing to Yosys. We have open [dev 'jour fixe' (JF) meetings](https://docs.google.com/document/d/1SapA6QAsJcsgwsdKJDgnGR2mr97pJjV4eeXg_TVJhRU/edit?usp=sharing) where developers from YosysHQ and the community come together to discuss open issues and PRs. This is also a good place to talk to us about how to implement larger PRs. + +## Using the issue tracker + +The [issue tracker](https://github.com/YosysHQ/yosys/issues) is used for +tracking bugs or other problems with Yosys or its documentation. It is also the +place to go for requesting new features. + +### Bug reports + +Learn more [here](https://yosyshq.readthedocs.io/projects/yosys/en/latest/yosys_internals/extending_yosys/contributing.html#reporting-bugs) about how to report bugs. We fix well-reported bugs the fastest. + +## Contributing code + +If you're adding complex functionality, or modifying core parts of Yosys, +we highly recommend discussing your motivation and approach +ahead of time on the [Discourse forum](https://yosyshq.discourse.group/). + +### Using pull requests + +If you are working on something to add to Yosys, or fix something that isn't +working quite right, +make a [pull request (PR)](https://github.com/YosysHQ/yosys/pulls). + +An open PR, even as a draft, tells everyone that you're working on it and they +don't have to. It can also be a useful way to solicit feedback on in-progress +changes. See above to find the best way to [ask us questions](#asking-questions). + +### Continuous integration + +[Continuous Integration (CI)](https://github.com/YosysHQ/yosys/actions) tools +automatically compile Yosys and run it with the full suite of tests. +If you're a first time contributor, a maintainer has to trigger a run for you. +We test on various platforms, compilers. Sanitizer builds are only tested +on the main branch. + +### Labels + +We use [labels](https://github.com/YosysHQ/yosys/labels) to help categorise +issues and PRs. If a label seems relevant to your work, please do add it; this +also includes the labels beginning with 'status-'. The 'merge-' labels are used +by maintainers for tracking and communicating which PRs are ready and pending +merge; please do not use these labels if you are not a maintainer. + + +### Coding style + +Learn more [here](https://yosys.readthedocs.io/en/latest/yosys_internals/extending_yosys/contributing.html). diff --git a/README.md b/README.md index 427d59c9e..3b2f41768 100644 --- a/README.md +++ b/README.md @@ -246,6 +246,8 @@ Building the documentation Note that there is no need to build the manual if you just want to read it. Simply visit https://yosys.readthedocs.io/en/latest/ instead. +If you're offline, you can read the sources, replacing `.../en/latest` +with `docs/source`. In addition to those packages listed above for building Yosys from source, the following are used for building the website: diff --git a/docs/source/yosys_internals/extending_yosys/contributing.rst b/docs/source/yosys_internals/extending_yosys/contributing.rst index 70170fc48..458d7dc36 100644 --- a/docs/source/yosys_internals/extending_yosys/contributing.rst +++ b/docs/source/yosys_internals/extending_yosys/contributing.rst @@ -1,57 +1,16 @@ Contributing to Yosys ===================== -.. note:: - - For information on making a pull request on github, refer to our - |CONTRIBUTING|_ file. - -.. |CONTRIBUTING| replace:: :file:`CONTRIBUTING.md` -.. _CONTRIBUTING: https://github.com/YosysHQ/yosys/blob/main/CONTRIBUTING.md - -Coding Style ------------- - -Formatting of code -~~~~~~~~~~~~~~~~~~ - -- Yosys code is using tabs for indentation. Tabs are 8 characters. - -- A continuation of a statement in the following line is indented by two - additional tabs. - -- Lines are as long as you want them to be. A good rule of thumb is to break - lines at about column 150. - -- Opening braces can be put on the same or next line as the statement opening - the block (if, switch, for, while, do). Put the opening brace on its own line - for larger blocks, especially blocks that contains blank lines. - -- Otherwise stick to the `Linux Kernel Coding Style`_. - -.. _Linux Kernel Coding Style: https://www.kernel.org/doc/Documentation/process/coding-style.rst - - -C++ Language -~~~~~~~~~~~~ - -Yosys is written in C++17. - -In general Yosys uses ``int`` instead of ``size_t``. To avoid compiler warnings -for implicit type casts, always use ``GetSize(foobar)`` instead of -``foobar.size()``. (``GetSize()`` is defined in :file:`kernel/yosys.h`) - -Use range-based for loops whenever applicable. - - Reporting bugs -------------- -- use the `bug report template`_ +A good bug report includes the following information: -.. _bug report template: https://github.com/YosysHQ/yosys/issues/new?template=bug_report.yml -- short title briefly describing the issue, e.g. +Title +~~~~~ + +briefly describe the issue, for example: techmap of wide mux with undefined inputs raises error during synth_xilinx @@ -64,10 +23,18 @@ Reporting bugs Reproduction Steps ~~~~~~~~~~~~~~~~~~ -- ideally a code-block (starting and ending with triple backquotes) containing - the minimized design (Verilog or RTLIL), followed by a code-block containing - the minimized yosys script OR a command line call to yosys with - code-formatting (starting and ending with single backquotes) +The reproduction steps should be a minimal, complete and verifiable +example `MVCE`_. +Providing an MVCE with your bug report drastically increases the likelihood that +someone will be able to help resolve your issue. +One way to minimize a design is to use the `bugpoint_` command. +You can learn more in the `how-to guide for bugpoint_`. + +The reproduction steps are ideally a code-block (starting and ending with +triple backquotes) containing +the minimized design (Verilog or RTLIL), followed by a code-block containing +the minimized yosys script OR a command line call to yosys with +code-formatting (starting and ending with single backquotes). .. code-block:: markdown @@ -86,9 +53,9 @@ Reproduction Steps `yosys -p ': minimum sequence of commands;' min.v` -- alternatively can provide a single code-block which includes the minimized - design as a "here document" followed by the sequence of commands which - reproduce the error +Alternatively, you can provide a single code-block which includes the minimized +design as a "here document" followed by the sequence of commands which +reproduce the error + see :doc:`/using_yosys/more_scripting/load_design` for more on heredocs. @@ -101,7 +68,9 @@ Reproduction Steps # minimum sequence of commands ``` -- any environment variables or command line options should also be mentioned +Don't forget to mention: + +- any important environment variables or command line options - if the problem occurs for a range of values/designs, what is that range - if you're using an external tool, such as ``valgrind``, to detect the issue, what version of that tool are you using and what options are you giving it @@ -115,46 +84,58 @@ Reproduction Steps around Yosys such as OpenLane; you should instead minimize your input and reproduction steps to just the Yosys part. -"Expected Behaviour" -~~~~~~~~~~~~~~~~~~~~ +.. _MVCE: https://stackoverflow.com/help/minimal-reproducible-example +.. _bugpoint: https://yosys.readthedocs.io/en/latest/cmd/bugpoint.html +.. _how-to guide for bugpoint: https://yosys.readthedocs.io/en/latest/using_yosys/bugpoint.html -- if you have a similar design/script that doesn't give the error, include it - here as a reference -- if the bug is that an error *should* be raised but isn't, are there any other - commands with similar error messages - - -"Actual Behaviour" +Expected Behaviour ~~~~~~~~~~~~~~~~~~ -- any error messages go here -- any details relevant to the crash that were found with ``--trace`` or - ``--debug`` flags -- if you identified the point of failure in the source code, you could mention - it here, or as a comment below +Describe what you'd expect to happen when we follow the reproduction steps +if the bug was fixed. - + if possible, use a permalink to the source on GitHub - + you can browse the source repository for a certain commit with the failure +If you have a similar design/script that doesn't give the error, include it +here as a reference. If the bug is that an error *should* be raised but isn't, +note if there are any other commands with similar error messages. + + +Actual Behaviour +~~~~~~~~~~~~~~~~ + +Describe what you actually see when you follow the reproduction steps. + +This can include: + +* any error messages +* any details relevant to the crash that were found with ``--trace`` or + ``--debug`` flags +* the part of the source code that triggers the bug + + * if possible, use a permalink to the source on GitHub + * you can browse the source repository for a certain commit with the failure and open the source file, select the relevant lines (click on the line number for the first relevant line, then while holding shift click on the line number for the last relevant line), click on the ``...`` that appears and select "Copy permalink" - + should look something like + * should look something like ``https://github.com/YosysHQ/yosys/blob//path/to/file#L139-L147`` - + clicking on "Preview" should reveal a code block containing the lines of + * clicking on "Preview" should reveal a code block containing the lines of source specified, with a link to the source file at the given commit -Additional details +Additional Details ~~~~~~~~~~~~~~~~~~ -- once you have created the issue, any additional details can be added as a - comment on that issue -- could include any additional context as to what you were doing when you first - encountered the bug -- was this issue discovered through the use of a fuzzer -- if you've minimized the script, consider including the `bugpoint` script you - used, or the original script, e.g. +Anything else you think might be helpful or relevant when verifying or fixing +the bug. + +Once you have created the issue, any additional details can be added as a +comment on that issue. You can include any additional context as to what you +were doing when you first encountered the bug. + +If this issue discovered through the use of a fuzzer, ALWAYS declare that. +If you've minimized the script, consider including the `bugpoint` script you +used, or the original script, for example: .. code-block:: markdown @@ -171,8 +152,226 @@ Additional details Minimized from `yosys -p ': original sequence of commands to produce error;' design.v` -- if you're able to, it may also help to share the original un-minimized design - - + if the design is too big for a comment, consider turning it into a `Gist`_ +If possible, it may also help to share the original un-minimized design. +If the design is too big for a comment, consider turning it into a `Gist`_ .. _Gist: https://gist.github.com/ + +Contributing code +----------------- + +Code that matters +~~~~~~~~~~~~~~~~~ + +If you're adding complex functionality, or modifying core parts of yosys, +we highly recommend discussing your motivation and approach +ahead of time on the `Discourse forum`_. Please, be as explicit and concrete +as possible when explaining the motivation for what you're building. +Additionally, if you do so on the forum first before you starting hacking +away at C++, you might solve your problem without writing a single line +of code! + +PRs are considered for relevance, priority, and quality +based on their descriptions first, code second. + +Before you build or fix something, also search for existing `issues`_. + +.. _`Discourse forum`: https://yosyshq.discourse.group/ +.. _`issues`: https://github.com/YosysHQ/yosys/issues + +Making sense +~~~~~~~~~~~~ + +Given enough effort, the behavior of any code can be figured out to any +desired extent. However, the author of the code is by far in the best +position to make this as easy as possible. + +Yosys is a long-standing project and has accumulated a lot of C-style code +that's not written to be read, just written to run. We improve this bit +by bit when opportunities arise, but it is what it is. +New additions are expected to be a lot cleaner. + +The purpose and behavior of the code changed should be described clearly. +Your change should contain exactly what it needs to match that description. +This means: + +* nothing more than that - no dead code, no undocumented features +* nothing missing - if something is partially built, that's fine, + but you have to make that clear. For example, some passes + only support some types of cells + +Here are some software engineering approaches that help: + +* Use abstraction to model the problem and hide details + + * Maximize the usage of types (structs over loose variables), + not necessarily in an object-oriented way + * Use functions, scopes, type aliases + +* In new passes, make sure the logic behind how and why it works is actually provided + in coherent comments, and that variable and type naming is consistent with the terms + you use in the description. +* The logic of the implementation should be described in mathematical + or algorithm theory terms. Correctness, termination, computational complexity. + Make it clear if you're re-implementing a classic data structure for logic synthesis + or graph traversal etc. + +* There's various ways of traversing the design with use-def indices (for getting + drivers and driven signals) available in Yosys. They have advantages and sometimes + disadvantages. Prefer not re-implementing these +* Prefer references over pointers, and smart pointers over raw pointers +* Aggressively deduplicate code. Within functions, within passes, + across passes, even against existing code +* Prefer declaring things ``const`` +* Prefer range-based for loops over C-style + +Common mistakes +~~~~~~~~~~~~~~~ + +* Deleting design objects invalidates iterators. Defer deletions or hold a copy + of the list of pointers to design objects +* Deleting wires can get sketchy and is intended to be done solely by + the ``opt_clean`` pass so just don't do it +* Iterating over an entire design and checking if things are selected is more + inefficient than using the ``selected_*`` methods +* Remember to call ``fixup_ports`` at the end if you're modifying module interfaces + +Testing your change +~~~~~~~~~~~~~~~~~~~ + +Untested code can't be maintained. Inevitable codebase-wide changes +are likely to break anything untested. Tests also help reviewers understand +the purpose of the code change in practice. + +Your code needs to come with tests. If it's a feature, a test that covers +representative examples of the added behavior. If it's a bug fix, it should +reproduce the original isolated bug. But in some situations, adding a test +isn't viable. If you can't provide a test, explain this decision. + +Prefer writing unit tests (:file:`tests/unit`) for isolated tests to +the internals of more serious code changes, like those to the core of yosys, +or more algorithmic ones. + +The rest of the test suite is mostly based on running Yosys on various Yosys +and Tcl scripts that manually call Yosys commands. +See :doc:`/yosys_internals/extending_yosys/test_suites` for more information +about how our test suite is structured. +The basic test writing approach is checking +for the presence of some kind of object or pattern with ``-assert-count`` in +:doc:`/using_yosys/more_scripting/selections`. + +It's often best to use equivalence checking with ``equiv_opt -assert`` +or similar to prove that the changes done to the design by a modified pass +preserve equivalence. But some code isn't meant to preserve equivalence. +Sometimes proving equivalence takes an impractically long time for larger +inputs. Also beware, the ``equiv_`` passes are a bit quirky and might even +have incorrect results in unusual situations. + +.. Changes to core parts of Yosys or passes that are included in synthesis flows +.. can change runtime and memory usage - for the better or for worse. This strongly +.. depends on the design involved. Such risky changes should then be benchmarked +.. with various designs. + +.. TODO Emil benchmarking + +Coding style +~~~~~~~~~~~~ + +Yosys is written in C++17. + +In general Yosys uses ``int`` instead of ``size_t``. To avoid compiler warnings +for implicit type casts, always use ``GetSize(foobar)`` instead of +``foobar.size()``. (``GetSize()`` is defined in :file:`kernel/yosys.h`) + +For auto formatting code, a :file:`.clang-format` file is present top-level. +Yosys code is using tabs for indentation. A tab is 8 characters wide, +but prefer not relying on it. A continuation of a statement +in the following line is indented by two additional tabs. Lines are +as long as you want them to be. A good rule of thumb is to break lines +at about column 150. Opening braces can be put on the same or next line +as the statement opening the block (if, switch, for, while, do). +Put the opening brace on its own line for larger blocks, especially +blocks that contains blank lines. Remove trailing whitespace on sight. + +Otherwise stick to the `Linux Kernel Coding Style`_. + +.. _Linux Kernel Coding Style: https://www.kernel.org/doc/Documentation/process/coding-style.rst + +Git style +~~~~~~~~~ + +We don't have a strict commit message style. + +Some style hints: + +* Refactor and document existing code if you touch it, + but in separate commits from your functional changes +* Prefer smaller commits organized by good chunks. Git has a lot of features + like fixup commits, interactive rebase with autosquash + +Reviewing PRs +------------- + +Reviewing PRs is a totally valid form of external contributing to the project! + +Who's the reviewer? +~~~~~~~~~~~~~~~~~~~ + +Yosys HQ is a company with the inherited mandate to make decisions on behalf +of the open source project. As such, we at HQ are collectively the maintainers. +Within HQ, we allocate reviews based on expertise with the topic at hand +as well as member time constraints. + +If you're intimately acquainted with a part of the codebase, we will be happy +to defer to your experience and have you review PRs. The official way we like +is our CODEOWNERS file in the git repository. What we're looking for in code +owners is activity and trust. For activity, if you're only interested in +a yosys pass for example for the time you spend writing a thesis, it might be +better to focus on writing good tests and docs in the PRs you submit rather than +to commit to code ownership and therefore to be responsible for fixing things +and reviewing other people's PRs at various unexpected points later. If you're +prolific in some part of the codebase and not a code owner, we still value your +experience and may tag you in PRs. + +As a matter of fact, the purpose of code ownership is to avoid maintainer +burnout by removing orphaned parts of the codebase. If you become a code owner +and stop being responsive, in the future, we might decide to remove such code +if convenient and costly to maintain. It's simply more respectful of the users' +time to explicitly cut something out than let it "bitrot". Larger projects like +LLVM or linux could not survive without such things, but Yosys is far smaller, +and there are expectations + +.. TODO this deserves its own section elsewhere I think? But it would be distracting elsewhere + +Sometimes, multiple maintainers may add review comments. This is considered +healthy collaborative even if it might create disagreement at times. If +somebody is already reviewing a PR, others, even non-maintainers are free to +leave comments with extra observations and alternate perspectives in a +collaborative spirit. + +How to review +~~~~~~~~~~~~~ + +First, read everything above about contributing. Those are the values you +should gently enforce as a reviewer. They're ordered by importance, but +explicitly, descriptions are more important than code, long-form comments +describing the design are more important than piecemeal comments, etc. + +If a PR is poorly described, incomplete, tests are broken, or if the +author is not responding, please don't feel pressured to take over their +role by reverse engineering the code or fixing things for them, unless +there are good reasons to do so. + +If a PR author submits LLM outputs they haven't understood themselves, +they will not be able to implement feedback. Take this into consideration +as well. We do not ban LLM code from the codebase, we ban bad code. + +Reviewers may have diverse styles of communication while reviewing - one +may do one thorough review, another may prefer a back and forth with the +basics out the way before digging into the code. Generally, PRs may have +several requests for modifications and long discussions, but often +they just are good enough to merge as-is. + +The CI is required to go green for merging. New contributors need a CI +run to be triggered by a maintainer before their PRs take up computing +resources. It's a single click from the github web interface.