3 The Mono runtime will implement the JIT engine (and a byte
4 code interpreter for quickly porting to new systems), the
5 class loader, the garbage collector, threading system and
6 metadata access libraries.
8 Currently the runtime has an image loader and metadata access
9 entry points. The runtime comes with a simple interpreter
10 that can execute very simple programs.
12 ** Executing MSIL/CIL images
14 The code will load an executable and map the references to
15 external assemblies to our own version of the assemblies on
18 Our roadmap looks like this, this has been updated as of
23 * Milestone 1: <b> Done</b> Fully read and parse all CIL byte-codes
24 and metadata tokens (ie, a disassembler).
26 * Milestone 2: Complete an interpreter for CIL byte
27 codes. This interpreter can be used temporarly to
28 run CIL byte code on a system where no JIT is
31 * Milestone 3: Define an <i>lburg</i>-like instruction
32 selector for the JITer for Intel. Although slower
33 at JITing than a streaming JITer, it generates
34 better code. The same grammar can later be used for
37 * Milestone 4: Implement JITer.
39 * Milestone 5: Port of the JITer to non IA32 systems.
42 A setup similar to the Kaffe JIT engine can be used to
43 layout the code to support non-IA32 architectures. Our work
44 will be focused on getting a IA32 version running first.
46 The JIT engine should work on Linux and Win32, although you
47 will need to install the CygWin32 development tools to get a
48 Unix-like compilation environment.
50 ** JIT Engine (<b>updated, Jul 14th, 2001</b>)
52 We will be using a code-generator generator approach for our
53 JITer. Given the properties of CIL byte codes, we can take
54 full advantage of a real instruction selector for our code
57 There are a couple of books that deal with this technique: "A
58 Retargetable C Compiler" and "Advanced Compiler Design and
59 Implementation" are good references. You can also get a
60 technical description of <a
61 href="http://research.microsoft.com/copyright/accept.asp?path=http://www.research.microsoft.com/~drh/pubs/iburg.pdf&pub=ACM">lbrug</a>
63 Previously we had looked at a number of JIT engines and tools,
64 but they would not take full advantage of the CIL properties:
68 href="http://www.intel.com/research/mrl/orp/">ORP</a>
71 href="http://www.gnu.org/software/lightning/">GNU
74 * <a href="http://www.eecs.harvard.edu/~nr/toolkit/">NJ Machine
82 We have decided to implement a generational tracing garbage
83 collector, which is very similar to the one being used by
84 .NET. For an introduction to the garbage collection system
85 used by Microsoft's CLR implementation, you can read this book
87 href="http://www.amazon.com/exec/obidos/ASIN/0471941484/o/qid=992556433/sr=2-1/ref=aps_sr_b_1_1/103-5866388-0492603">Garbage
90 Another consideration is to use the same interface that ORP
91 uses to its Garbage Collection system and reuse that GC system
92 instead of rolling our own, as the ORP system is pretty advanced
93 and is independent of the rest of ORP.
95 Although using a conservative garbage collector like Bohem's
96 would work, all the type information is available at runtime,
97 so we can actually implement a better collector than a
98 conservative collector.
101 * Garbage collection list and FAQ:<br>
102 <a href="http://www.iecc.com/gclist/">http://www.iecc.com/gclist/</a>
104 * "GC points in a Threaded Environment":<br>
105 <a href="http://research.sun.com/techrep/1998/abstract-70.html">
106 http://research.sun.com/techrep/1998/abstract-70.html</a>
108 * "A Generational Mostly-concurrent Garbage Collector":
109 <a href="http://research.sun.com/techrep/2000/abstract-88.html">
110 http://research.sun.com/techrep/2000/abstract-88.html</a>
112 * Details on The Microsoft .NET Garbage Collection Implementation:<br>
113 <a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnmag00/html/GCI.asp">http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnmag00/html/GCI.asp</a>
114 <a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnmag00/html/GCI2.asp">http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnmag00/html/GCI2.asp</a>
119 Paolo Molaro found a few interesting links:
122 * On compilation of stack-based languages:<br>
123 <a href="http://www.complang.tuwien.ac.at/projects/rafts.html">
124 http://www.complang.tuwien.ac.at/projects/rafts.html</a>
126 * A paper on fast JIT compilation of a stack-based language:<br>
127 <a href="http://www.research.microsoft.com/~cwfraser/pldi99codegen.pdf">
128 http://www.research.microsoft.com/~cwfraser/pldi99codegen.pdf</a>
130 * Vmgen generates much of the code for efficient virtual machine (VM)
131 interpreters from simple descriptions of the VM instructions:<br>
132 <a href="http://www.complang.tuwien.ac.at/anton/vmgen/">
133 http://www.complang.tuwien.ac.at/anton/vmgen</a>
138 PInvoke is the mechanism we are using to wrap Unix API calls
139 as well as talking to system libraries.
141 We hvae implemented PInvoke through libffi, but we are likely
142 going to roll our own system as the runtime matures, specially
143 as the interpreter is approaching completion, and we move into