* MCS: The Ximian C# compiler
- MCS is currently able to compile small C# programs (there is
- a test suite included that you can use).
+ The Mono C# compiler is considered feature complete at this
+ point and relatively mature. MCS is able to compile itself
+ and many more C# programs (there is a test suite included that
+ you can use). It is routinely used to compile Mono, roughly
+ half a million lines of C# code.
- We are in feature completion mode right now. There are still
- a couple of areas that are not covered by the Mono compiler, but
- they are very very few at this point.
+** Obtaining MCS
- Although MCS has been able to parse itself since April,
- it can not yet compile itself. We are working hard towards
- mkaing the compiler self hosting in Linux.
+ The Mono C# compiler is part of the `mcs' module in the Mono CVS
+ you can get it from our <a href="anoncvs.html">Anonymous CVS</a> server,
+ or you can get nightly <a href="download.html">download page</a>.
- A test suite is being built currently to track the progress of
- the compiler and various programs are routinely compiled and
- ran.
+** Running MCS
+
+ MCS is written in C# and uses heavily the .NET APIs. MCS runs
+ on Linux with the Mono runtime and on Windows with both the
+ .NET runtime and the Mono runtime.
+
+** Reporting Bugs in MCS
+
+ When you report a bug, try to provide a small test case that would
+ show the error so we can include this as part of the Mono C# regression
+ test suite.
+
+ If the bug is an error or a warning that we do not flag, write
+ a sample program called `csXXXX.cs' where XXXX is the code number
+ that is used by the Microsoft C# compiler that illustrates the
+ problem. That way we can also do regression tests on the invalid
+ input.
** Phases of the compiler
* Code generation: The code generation is done through
the System.Reflection.Emit API.
-
</ul>
-<a name="tasks">
-** Current pending tasks
+** CIL Optimizations.
- Simple tasks:
+ The compiler performs a number of simple optimizations on its input:
+ constant folding (this is required by the C# language spec) and
+ can perform dead code elimination.
- <ul>
- * Extern declarations are missing.
- </ul>
+ Other more interesting optimizations like hoisting are not possible
+ at this point since the compiler output at this point does not
+ generate an intermediate representation that is suitable to
+ perform basic block computation.
- Larger tasks:
+ Adding an intermediate layer to enable the basic block
+ computation to the compiler should be a simple task, but we
+ are considering having a generic CIL optimizer. Since all the
+ information that is required to perform basic block-based
+ optimizations is available at the CIL level, we might just skip
+ this step altogether and have just a generic IL optimizer that
+ would perform hoisting on arbitrary CIL programs, not only
+ those produced by MCS.
- <ul>
- * Finish constant folding.
- </ul>
+ If this tool is further expanded to perform constant folding
+ (not needed for our C# compiler, as it is already in there)
+ and dead code elimination, other compiler authors might be
+ able to use this generic CIL optimizer in their projects
+ reducing their time to develop a production compiler.
- Interesting and Fun hacks to the compiler:
+* Open bugs
- <ul>
+ See the <a href="bugs.html">bugs page</a> for more information.
- * Jay does not work correctly with `error'
- productions, making parser errors hard to point. It
- would be best to port the Bison-To-Java compiler to
- become Bison-to-C# compiler.
-
- Nick Drochak has started a project on SourceForge for this.
- You can find the project at: <a href="http://sourceforge.net/projects/jb2csharp/">
- http://sourceforge.net/projects/jb2csharp/</a>
+ A test suite is maintained to track the progress of
+ the compiler and various programs are routinely compiled and
+ ran.
- * Semantic Analysis: Return path coverage and
- initialization before use coverage are two great
- features of C# that help reduce the number of bugs
- in applications. It is one interesting hack.
+* Slides
- </ul>
+ Slides for the Mono C# Compiler presentation at .NET ONE are
+ available <a
+ href="http://primates.ximian.com/~miguel/slides-europe-nov-2002/Mono_C_Sharp_Overview_1007.sxi">here</a>
+ in StarOffice format.
+
+** History
+
+ MCS was able to parse itself on April 2001, MCS compiled itself
+ for the first time on December 28 2001. MCS became self hosting
+ on January 3rd, 2002.
+
+ The Mono Runtime and the Mono execution engine were able to make
+ our compiler self hosting on March 12, 2002.
** Questions and Answers
+Q: Does the Mono C# compiler support C# 2.0?
+
+A: At this point the Mono C# compiler supports some of the features of
+ C# 2.0, but the support has not been completed. To enable 2.0 features
+ you must use the -2 flag to the compiler.
+
+Q: What features are available as of Feb 2004?
+
+A: Iterators have been implemented as well as method group implicit
+ conversion to delegates on the main compiler branch.
+
+ We have a branch of the compiler in the module `mcs/gmcs' which is
+ where we are developing the Generics support for the compiler. Plenty
+ of tests work (see mcs/tests/gen-*.cs for a list of tests), but work
+ remains to be done.
+
+Q: Will the C# 2.0 features be part of the Mono 1.0 release?
+
+A: Only a few, the generic compiler will not be part of the 1.0
+ stable release, but a beta preview will be distributed.
+
Q: Why not write a C# front-end for GCC?
A: I wanted to learn about C#, and this was an exercise in this
We will do this through an implementation of the CLI Virtual
Execution System for Unix (our JIT engine).
+ Our JIT engine is working for the purposes of using the compiler.
+ The supporting class libraries are being worked on to fully support
+ the compiler.
+
Q: Do you use Bison?
A: No, currently I am using Jay which is a port of Berkeley Yacc to
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