4afb28ef59
* Use wabt for wasm testing. * Use wabt in cton-util. * Make the wasm subcommand optional.
149 lines
5.1 KiB
ReStructuredText
149 lines
5.1 KiB
ReStructuredText
=======================
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Cretonne Code Generator
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=======================
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Cretonne is a low-level retargetable code generator. It translates a `target-independent
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intermediate representation <https://cretonne.readthedocs.io/en/latest/langref.html>`_ into executable
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machine code.
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.. image:: https://readthedocs.org/projects/cretonne/badge/?version=latest
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:target: https://cretonne.readthedocs.io/en/latest/?badge=latest
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:alt: Documentation Status
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.. image:: https://travis-ci.org/cretonne/cretonne.svg?branch=master
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:target: https://travis-ci.org/cretonne/cretonne
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:alt: Build Status
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.. image:: https://badges.gitter.im/cretonne/cretonne.svg
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:target: https://gitter.im/cretonne/Lobby/~chat
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:alt: Gitter chat
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For more information, see `the documentation
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<https://cretonne.readthedocs.io/en/latest/?badge=latest>`_.
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Status
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------
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Cretonne currently supports enough functionality to run a wide variety of
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programs, including all the functionality needed to execute WebAssembly MVP
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functions, although it needs to be used within an external WebAssembly
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embedding to be part of a complete WebAssembly implementation.
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The x86-64 backend is currently the most complete and stable; other
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architectures are in various stages of development. Cretonne currently supports
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the System V AMD64 ABI calling convention used on many platforms, but does not
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yet support the Windows x64 calling convention. The performance of code
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produced by Cretonne is not yet impressive, though we have plans to fix that.
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The core codegen crates have minimal dependencies, support
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`no_std <#building-with-no-std>`_ mode, and do not require any host
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floating-point support.
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Cretonne does not yet perform mitigations for Spectre or related security
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issues, though it may do so in the future. It does not currently make any
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security-relevant instruction timing guarantees. It has seen a fair amount
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of testing and fuzzing, although more work is needed before it would be
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ready for a production use case.
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Cretonne's APIs are not yet stable.
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Cretonne currently supports Rust 1.22.1 and later. We intend to always support
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the latest *stable* Rust. And, we currently support the version of Rust in the
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latest Ubuntu LTS, although whether we will always do so is not yet determined.
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Cretonne requires Python 2.7 or Python 3 to build.
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Planned uses
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------------
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Cretonne is designed to be a code generator for WebAssembly, but it is general enough to be useful
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elsewhere too. The initial planned uses that affected its design are:
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1. `WebAssembly compiler for the SpiderMonkey engine in Firefox
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<spidermonkey.rst#phase-1-webassembly>`_.
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2. `Backend for the IonMonkey JavaScript JIT compiler in Firefox
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<spidermonkey.rst#phase-2-ionmonkey>`_.
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3. `Debug build backend for the Rust compiler <rustc.rst>`_.
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Building Cretonne
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-----------------
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Cretonne is using the Cargo package manager format. First, ensure you have
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installed a current stable rust (stable, beta, and nightly should all work, but
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only stable and beta are tested consistently). Then, change the working
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directory to your clone of cretonne and run::
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cargo build
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This will create a *target/debug* directory where you can find the generated
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binary.
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To build the optimized binary for release::
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cargo build --release
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You can then run tests with::
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./test-all.sh
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Building with `no_std`
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----------------------
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The following crates support `no_std`:
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- `cretonne-entity`
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- `cretonne-codegen`
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- `cretonne-frontend`
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- `cretonne-native`
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- `cretonne-wasm`
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- `cretonne-module`
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- `cretonne-simplejit`
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- `cretonne`
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To use `no_std` mode, disable the `std` feature and enable the `core` feature.
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This currently requires nightly rust.
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For example, to build `cretonne-codegen`:
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.. code-block:: sh
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cd lib/codegen
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cargo build --no-default-features --features core
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Or, when using `cretonne-codegen` as a dependency (in Cargo.toml):
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.. code-block::
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[dependency.cretonne-codegen]
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...
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default-features = false
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features = ["core"]
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`no_std` support is currently "best effort". We won't try to break it, and
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we'll accept patches fixing problems, however we don't expect all developers to
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build and test `no_std` when submitting patches. Accordingly, the
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`./test-all.sh` script does not test `no_std`.
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There is a separate `./test-no_std.sh` script that tests the `no_std`
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support in packages which support it.
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It's important to note that cretonne still needs liballoc to compile.
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Thus, whatever environment is used must implement an allocator.
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Also, to allow the use of HashMaps with `no_std`, an external crate called
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`hashmap_core` is pulled in (via the `core` feature). This is mostly the same
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as `std::collections::HashMap`, except that it doesn't have DOS protection.
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Just something to think about.
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Building the documentation
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--------------------------
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To build the Cretonne documentation, you need the `Sphinx documentation
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generator <https://www.sphinx-doc.org/>`_::
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$ pip install sphinx sphinx-autobuild sphinx_rtd_theme
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$ cd cretonne/docs
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$ make html
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$ open _build/html/index.html
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We don't support Sphinx versions before 1.4 since the format of index tuples
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has changed.
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