962c945a3c
* API and data structures proposal for the SSA construction module * Polished API and implemented trivial functions * API more explicit, Variable now struct parameter * Sample test written to see how the API could be used * Implemented local value numbering for SSABuilder * Implemented SSA within a single Ebb * Unfinished unoptimized implementation for recursive use and seal * Working global value numbering The SSABuilder now create ebb args and modifies jump instructions accordingly * Updated doc and improved branch argument modifying. Removed instructions::branch_arguments and instructions::branch_argument_mut * SSA building: bugfix, asserts and new test case Missing a key optimization to remove cycles of Phi * SSA Building: small changes after code review Created helper function for seal_block (which now contains sanity checks) * Optimization: removed useless phis (ebb arguments) Using pessimistic assumption that when using a non-def variable in an unsealed block we create an ebb argument which is removed when sealing if we detect it as useless Using aliases to avoid rewriting variables * Changed the semantics of remove_ebb_arg and turned it into a proper API method * Adapted ssa branch to changes in the DFG API * Abandonned SparseMaps for EntityMaps, added named structure for headr block data. * Created skeletton for a Cretonne IL builder frontend * Frontend IL builder: first draft of implementation with example of instruction methods * Working basic implementation of the frontend Missing handling of function arguments and return values * Interaction with function signature, sample test, more checks * Test with function verifier, seal and fill sanity check * Implemented python script to generate ILBuilder methods * Added support for jump tables and stack slot * Major API overhaul * No longer generating rust through Python but implements InstBuilder * No longer parametrized by user's blocks but use regular `Ebb` * Reuse of allocated memory via distinction between ILBuilder and FunctionBuilder * Integrate changes from StackSlot * Improved error message * Added support for jump arguments supplied by the user * Added an ebb_args proxy method needed * Adapted to Entity_ref splitted into a new module * Better error messages and fixed tests * Added method to change jump destination * We whould be able to add unreachable code * Added inst_result proxy to frontend * Import support * Added optimization for SSA construction: If multiple predecessors but agree on value don't create EBB argument * Move unsafe and not write-only funcs apart, improved doc * Added proxy function for append_ebb_arg * Support for unreachable code and better layout of the Ebbs * Fixed a bug yielding an infinite loop in SSA construction * SSA predecessors lookup code refactoring * Fixed bug in unreachable definition * New sanity check and display debug function * Fixed bug in verifier and added is_pristine ;ethod for frontend * Extended set of characters printable in function names To be able to print names of functions in test suite * Fixes and improvements of SSA construction after code review * Bugfixes for frontend code simplification * On-the-fly critical edge splitting in case of br_table with jump arguments * No more dangling undefined values, now attached as EBB args * Bugfix: only split corresponding edges on demand, not all br_table edges * Added signature retrieval method * Bugfix for critical edge splitting not sealing the ebbs it created * Proper handling of SSA side effects by the frontend * Code refactoring: moving frontend and SSA to new crate * Frontend: small changes and bugfixes after code review
=======================
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 a current stable rust (stable, beta, and nightly should all work, but
only stable and beta are tested consistently). 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 sphinx-autobuild sphinx_rtd_theme
$ cd cretonne/docs
$ make html
$ open _build/html/index.html
We don't support Sphinx versions before 1.4 since the format of index tuples
has changed.