| 1 | cfa-cc: The Cforall->C Compiler System
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| 2 | ======================================
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| 3 |
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| 4 | This is a PRE-RELEASE version of cfa-cc. It exists solely for the purpose of
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| 5 | private experimentation and scholarly research. The authors disclaim all
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| 6 | responsibility for the consequences of any malfunction of the software,
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| 7 | including the malfunction of any programs compiled using the software.
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| 8 |
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| 9 | What is Cforall?
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| 10 | ----------------
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| 11 | Cforall is a language design extending ISO C. The purpose of the project is to
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| 12 | engineer modern language features into C in an evolutionary rather than
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| 13 | revolutionary way. Java is an example of the revolutionary approach of
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| 14 | modernizing C/C++, resulting in a new language rather than an extension of its
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| 15 | descendents. C++, Fortran 95 and Cobol 9X are examples of the evolutionary
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| 16 | approach where modern language features are added and problems fixed within the
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| 17 | framework of an existing language.
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| 18 |
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| 19 | The goal of this project is to produce a largely backwards compatible version
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| 20 | of C containing many modern language features and fixing some of the well known
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| 21 | C problems. Without continued development of the language, C will be unable to
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| 22 | cope with the needs of modern programming problems and programmers; as a
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| 23 | result, it will fade into disuse. Considering the large body of existing C
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| 24 | code and programmers, there is a significant impetus to ensure C is transformed
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| 25 | into a modern programming language.
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| 26 |
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| 27 | What is cfa-cc?
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| 28 | ---------------
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| 29 | cfa-cc is a collection of programs centred around a translator that takes
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| 30 | Cforall code as input and outputs corresponding C code. This is complemented
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| 31 | by a compiler driver in the style of "gcc", which handles preprocessing,
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| 32 | compiling, assembling, and linking and invokes the translator at appropriate
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| 33 | moments.
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| 34 |
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| 35 | What is required in order to use cfa-cc?
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| 36 | ----------------------------------------
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| 37 | Building cfa-cc requires GNU Make and gcc/g++ 4. cfa-cc is written in C++.
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| 38 |
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| 39 | The compiler driver uses an installed version of gcc to handle all aspects of
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| 40 | the compilation process except for the Cforall->C translation. Currently, only
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| 41 | gcc 4.x is supported.
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| 42 |
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| 43 | How is cfa-cc used?
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| 44 | -------------------
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| 45 | The compiler driver "cfa" accepts all of the arguments of gcc, and is used in
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| 46 | the same way. For example:
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| 47 |
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| 48 | cfa -c test.c
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| 49 | cfa test.o
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| 50 |
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| 51 | Cforall source files must end with '.c' in order to be compiled by the compiler
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| 52 | driver. In addition, the flag "-CFA" causes cfa to invoke the preprocessor and
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| 53 | translator and send the translator output to standard output.
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| 54 |
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| 55 | It is possible to invoke the translator directly. The translator is installed
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| 56 | by default as /usr/local/lib/cfa-cpp. A typical invocation is:
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| 57 |
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| 58 | /usr/local/lib/cfa-cpp -cp infile outfile
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| 59 |
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| 60 | If outfile is omitted, output goes to standard output; if infile is also
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| 61 | omitted, input comes from standard input. Options to the translator other than
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| 62 | "-cp" will not produce valid C code and are only useful for debugging the
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| 63 | translator.
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| 64 |
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| 65 | How can C code be used with cfa-cc?
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| 66 | -----------------------------------
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| 67 | cfa-cc should be able to compile most ANSI C programs. It is also possible to
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| 68 | link against C libraries in most cases. Since Cforall supports overloading,
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| 69 | however, names used in Cforall code are mangled in the output C code. This
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| 70 | caused linker failures when the names refer to functions and objects in code
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| 71 | compiled with a standard C compiler. For this reason, it is necessary to
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| 72 | enclose the declarations of these functions and objects in extern "C" {}
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| 73 | blocks. For example:
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| 74 |
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| 75 | extern "C" {
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| 76 | #include <stdio.h>
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| 77 | #include <stdlib.h>
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| 78 | }
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| 79 |
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| 80 | The extern "C" turns off name mangling for functions and objects declared
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| 81 | within the block. As a result, it is not possible to overload their names.
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| 82 |
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| 83 | What's wrong with cfa-cc?
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| 84 | -------------------------
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| 85 |
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| 86 | The authors consider this software to be in an unstable state. It is quite
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| 87 | likely that there are many reasonable programs that will fail to compile. We
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| 88 | encourage users to report their experiences to cforall@plg.uwaterloo.ca, but we
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| 89 | make no promises regarding support.
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| 90 |
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| 91 | We have fixed most of the problems that we are aware of. There are some
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| 92 | exceptions:
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| 93 |
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| 94 | - initializers are poorly implemented; in particular, file-scope initializers
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| 95 | may result in the generation of invalid C code
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| 96 |
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| 97 | - the ISO C99 designated initialization syntax '[n] = m' or '.n = m' is not
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| 98 | supported; use a colon in place of the equal sign
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| 99 |
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| 100 | - some legitimate programs will produce warnings from the C compiler; these are
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| 101 | harmless (in particular, the creation of libcfa.a in the build process should
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| 102 | cause four warnings from gcc)
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| 103 |
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| 104 | - abstract types introduced using the keyword 'type' are not implemented
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| 105 | (although 'type' can be used to introduce type parameters)
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| 106 |
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| 107 | - the implicit coercion of structure types to the type of their first member is
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| 108 | not implemented
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| 109 |
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| 110 | Who is responsible for cfa-cc?
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| 111 | ------------------------------
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| 112 | cfa-cc was written by Peter Buhr, Richard Bilson, and Rodolfo Esteves.
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| 113 | Questions and comments can be sent to cforall@plg.uwaterloo.ca.
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| 114 |
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| 115 | The Cforall project maintains a web page:
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| 116 |
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| 117 | https://cforall.uwaterloo.ca
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