A Microsoft .NET Front-End for GCC

1
A Microsoft .NET Front-End for GCC

• Bernhard Rabe
• Martin von Löwis
• Jan Möller
• Operating Systems Middleware Group
• Hasso-Plattner-Institute, University of Potsdam

2
Outline

• Motivation
• GCC
• CIL Front-End
• Targets
• Internals
• Example
• Status
• Conclusions

3
Vision

• Extending the reach of Middleware
• Today
• What else?

4
GNU Compiler Collection
C
x86 asm
GCC

• Different programming languages (C, C, Java,
  Ada,)
• Various (micro)processor architectures (H8300,
  ARM, AVR, i386, )
• Easy extensibility to new architectures

C
mips asm
RTL
Java
arm asm
Front-ends
Back-ends
5
CIL Front-End
C
x86 asm
.NET Compiler
GCC
C
IL Assembly
h8/300 asm

• We use the Portable.NET IL libraries to read
  .NET assemblies
• Transforms IL code into GCC internal tree
  representation
• memory layout of objects
• vtables and emits RTL code for each method
• All .NET concepts except dynamic loading can be
  supported

VB
6
Target platforms

• Lego Mindstorm Robots
• Lego.NET
• RCX 2.0 (Renesas H8/300, 16Bit, 16 Mhz)
• 32K RAM
• no floating point support
• Real-Time Control System
• Real-Time .Net
• Windows CE (x86,600 Mhz)
• Thread support (delegates)
• (Hard) real-time constraints (Higher Striker)

7
Implementation Internals

• Runtime system for each supported target
• Mono application binary interface (ABI)
• object layout (MonoObject)
• string and array layout
• vtable layout
• method calling convention
• Floating point support (emulation or hardware if
  available)
• support only beforefieldinit classes
• anytime before first access
• initialization is done at program start

8
excerpt from example.cs

• cab3 tree nodes
• ldloc.0
• ldloc.1
• ldc.i4.3
• mul
• add
• stloc.2

VAR_DECL LOC0
VAR_DECL LOC1
INTEGER_CST 3
MUL_EXPR
9
excerpt from example.cs

• cab3 tree nodes
• ldloc.0
• ldloc.1
• ldc.i4.3
• mul
• add
• stloc.2

VAR_DECL LOC0
VAR_DECL LOC1
INTEGER_CST 3
MUL_EXPR
ADD_EXPR
10
excerpt from example.cs

• cab3 tree nodes
• ldloc.0
• ldloc.1
• ldc.i4.3
• mul
• add
• stloc.2

VAR_DECL LOC0
VAR_DECL LOC1
INTEGER_CST 3
MUL_EXPR
ADD_EXPR
VAR_DECL LOC2
11
excerpt from example.cs

• cab3 tree nodes
• ldloc.0
• ldloc.1
• ldc.i4.3
• mul
• add
• stloc.2

VAR_DECL LOC0
VAR_DECL LOC1
INTEGER_CST 3
MUL_EXPR
ADD_EXPR
VAR_DECL LOC2
MODIFY_EXPR
12
excerpt from example.cs

• cab3 tree nodes
• ldloc.0
• ldloc.1
• ldc.i4.3
• mul
• add
• stloc.2

VAR_DECL LOC0
VAR_DECL LOC1
INTEGER_CST 3
MUL_EXPR
ADD_EXPR
VAR_DECL LOC2
MODIFY_EXPR
expand_expr(MODIFY_EXPR) Backend emits assembly
language
13
gcc O2 S example.dll

• x86 Backend, excerpt from example.s
• movl 12(ebp), eax eax b
• leal (eax,eax,2), eax eax eax2eax
• addl 8(ebp), eax eax a

14
Supported Constructs

• primitive data types, enums
• classes, attributes (static, instance),
  properties, inheritance
• methods (static, instance), parameters, local
  variables and constructors
• arrays and strings
• delegates
• arithmetic operations
• control flow operations (conditional,
  unconditional branch, switch)

15
Conclusions

• CIL front-end for GCC
• Support for target processors not supported
  otherwise (commercial framework, or compact
  framework)
• Programming Lego Mindstorms Robots
• http//www.dcl.hpi.uni-potsdam.de/research/lego.NE
  T/
• Future Work
• Real-time extensions (Real-Time .Net)
• interfaces, reflection, exception handling
• GC

16

• Questions?
• gcc_at_hpi.uni-potsdam.de