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Cretonne Code Generator
=======================

Cretonne is a low-level retargetable code generator. It translates a
target-independent intermediate language into executable machine code.

*This is a work in progress that is not yet functional.*

.. image:: https://readthedocs.org/projects/cretonne/badge/?version=latest
    :target: https://cretonne.readthedocs.io/en/latest/?badge=latest
    :alt: Documentation Status

.. image:: https://travis-ci.org/stoklund/cretonne.svg?branch=master
    :target: https://travis-ci.org/stoklund/cretonne
    :alt: Build Status

Cretonne is designed to be a code generator for WebAssembly with these design
goals:

No undefined behavior
    Cretonne does not have a `nasal demons clause <http://www.catb.org/jargon/html/N/nasal-demons.html>`_, and it won't generate code
    with unexpected behavior if invariants are broken.
Portable semantics
    As far as possible, Cretonne's input language has well-defined semantics
    that are the same on all target architectures. The semantics are usually
    the same as WebAssembly's.
Fast sandbox verification
    Cretonne's input language has a safe subset for sandboxed code. No advanced
    analysis is required to verify memory safety as long as only the safe
    instructions are used. The safe instruction set is expressive enough to
    implement WebAssembly.
Scalable performance
    Cretonne can be configured to generate code as quickly as possible, or it
    can generate very good code at the cost of slower compile times.
Predictable performance
    When optimizing, Cretonne focuses on adapting the target-independent IL to
    the quirks of the target architecture. There are no advanced optimizations
    that sometimes work, sometimes fail.

Building Cretonne
-----------------

Cretonne is using the Cargo package manager format. First, ensure you have
installed `rust 1.12.0` or above. Then, change the working directory to your
clone of cretonne and run::

    cargo build

This will create a *target/debug* directory where you can find the generated
binary.

To build the optimized binary for release::

    cargo build --release

You can then run tests with::

    ./test-all.sh

Building the documentation
--------------------------

To build the Cretonne documentation, you need the `Sphinx documentation
generator <http://www.sphinx-doc.org/>`_::

    $ pip install sphinx==1.3.5 sphinx-autobuild
    $ cd cretonne/docs
    $ make html
    $ open _build/html/index.html

The specific Sphinx version is currently used by Read the Docs. Sphinx 1.4 has
been released, but produces lots of warnings about four-column indices. We'll
upgrade when Read the Docs does.