building a compiler

Universität Dortmund

Building a compiler
(considering characteristics of embedded processors)

Peter Marwedel
University of Dortmund, Germany

 P. Marwedel, Univ. Dortmund/Informatik 12 + ICD/ES, 2006

Fri2 - 1 -

Universität Dortmund

Effort for building a compiler
 So far we assumed that all the optimizations can be added to some existing tool chain.
 Sometimes, a custom compiler is required, but: the effort for building a custom compiler is underestimated.
 It is not sufficient to design a processor and then think about the compiler later.
 Try to avoid the design of a full compiler. Approaches:
- Modify an existing compiler.
- Implement proposed optimizations as pre- or postpass optimization.
- Use existing standard software components
- Use retargetable compiler (see below)
 What if we have to look at the entire compiler ? 
 P. Marwedel, Univ. Dortmund/Informatik 12 + ICD/ES, 2006

Fri2 - 2 -

Universität Dortmund

Anatomy of a compiler
Compiler
C-source

frontend

HL-IR

HL2LL

LL-IR

backend

optimizations

ASM

assembler

OBJ

linker

EXE

Do not start from scratch!
 P. Marwedel, Univ. Dortmund/Informatik 12 + ICD/ES, 2006

Fri2 - 3 -

Universität Dortmund

Existing Compiler Frameworks: gcc
GNU Compiler Collection (GNU public license)
Family of C & C++ compilers
(also supports Java and Fortran)
Available for many different architectures
(e.g. Sparc, Mips, Alpha)
 Code-transformation into an IR (Intermediate
Representation) called RTL (Register Transfer
Language)
 Designed for homogeneous register machines
 No ideal fit for embedded processors based on slide by
(heterogeneous registers etc.)
Désirée Kraus, Inf 12, 2005
 P. Marwedel, Univ. Dortmund/Informatik 12 + ICD/ES, 2006

Fri2 - 4 -

Universität Dortmund

Existing Compiler Frameworks: lcc
Little C Compiler (Princeton University)
„lightweight compiler“ (~ 13.000 lines of code)
„A retargetable C