Codemist Compilers / Norcroft

The main business of Codemist Ltd is in the creation of high quality compilers for specific processors. This work is usually undertaken on behalf of chip manufacturers rather than for the end user. We specialise in optimising ANSI C compilers, and especially innovative processors, using register allocation by colouring, global common subexpression elimination (CSE), and instruction scheduling. We have created C compilers for a range of computers, from mainframes to embedded special purpose chips.

We are not at liberty to list all the compilers we have created for our customers, but the following partial list will give an idea of the range of our output. It includes 16 bit and 32 bit processors as well as some unusual architectures.

• Acorn Computers ARM C Compiler. This is the original ANSI C compiler known as Norcroft C.
• INMOS Transputer C Compiler written in conjunction with Perihelion Software Ltd.
• Hitachi for their mainframe (IBM compatible)
• ICL KCM the Knowledge Crunching Machine
• Matsushita Adenart experimental graphics processor
• AIH324
• Cambridge Consultants XAP low power processor; also the ECOG-1.
• NEC 860

• AMD 29000
• DEC Alpha
• Gould NP1
• IBM 370
• Intel Pentium for Linux
• Intel i860 with Perihelion Software Ltd
• Intergraph Clipper
• MIPS for various machines
• Motorola 68K with Perihelion Software Ltd
• Motorola 88K
• National Semiconductor 320xx
• SPARC for SUN and ICL machines

Further Information

As many small embedded processors do not have hardware floating point, Codemist provide a C Compiler option and a C-coded IEEE floating point arithmetic library so that machines with only integer operations can adhere to the ANSI standard with no additional work for the client. Thus lack of additional silicon is not a barrier to a full ANSI C implementation.

The general design of the Norcroft C compiler is described in a small number of internal reports, available to potential customers from Codemist.

• The internal structure of the Norcroft C compiler 1986
• Implementation decisions for `C' on non-standard architectures 1992
  The document considers the effects of possible implementation choices for `C' data types and operations on run-time efficiency and (Unix-)user-friendliness, particularly for architectures in which these do not coincide. It is specifically oriented at Codemist's `Norcroft' C compiler but applies to any implementation of C.
• The Norcroft compiler suite; technical overview and details 1993
  The Norcroft compiler suite is a portable (across host and target systems) set of compilers for a variety of languages. It consists of a set of interchangeable (language dependent) front-ends which interface to a common intermediate code generator and optimiser (the `middle'-end) and a set of back-ends for most common RISC and CISC architectures. The interface to the back-end is clean and narrow which means that implementing the compilers for a new architecture is relatively fast. Re-hosting them is also easy - the compilers have been written to be insensitive to byte ordering and floating point representation of the host on which they are run, so cross compiling from one machine to another is possible, either as a step in porting the code to a new target or in support of embedded processors.

Information for Potential Customers