| 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
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| 5 | purpose of private experimentation and scholarly research. The authors
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| 6 | disclaim all responsibility for the consequences of any malfunction of
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| 7 | the software, including the malfunction of any programs compiled using
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| 8 | the software.
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| 9 |
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| 10 | What is Cforall?
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| 11 | ----------------
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| 12 | Cforall is a language design extending ISO C. The purpose of the
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| 13 | project is to engineer modern language features into C in an
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| 14 | evolutionary rather than revolutionary way. Java is an example of the
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| 15 | revolutionary approach of modernizing C/C++, resulting in a new
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| 16 | language rather than an extension of its descendents. C++, Fortran 95
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| 17 | and Cobol 9X are examples of the evolutionary approach where modern
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| 18 | language features are added and problems fixed within the framework of
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| 19 | an existing language.
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| 20 |
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| 21 | The goal of this project is to produce a largely backwards compatible
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| 22 | version of C containing many modern language features and fixing some
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| 23 | of the well known C problems. Without continued development of the
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| 24 | language, C will be unable to cope with the needs of modern programming
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| 25 | problems and programmers; as a result, it will fade into disuse.
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| 26 | Considering the large body of existing C code and programmers, there is
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| 27 | a significant impetus to ensure C is transformed into a modern
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| 28 | programming language.
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| 29 |
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| 30 | What is cfa-cc?
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| 31 | ---------------
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| 32 | cfa-cc is a collection of programs centred around a translator that
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| 33 | takes Cforall code as input and outputs corresponding C code. This
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| 34 | is complemented by a compiler driver in the style of "gcc", which
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| 35 | handles preprocessing, compiling, assembling, and linking and invokes
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| 36 | the translator at appropriate moments.
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| 37 |
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| 38 | What is required in order to use cfa-cc?
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| 39 | ----------------------------------------
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| 40 | Building cfa-cc requires GNU Make and gcc/g++ 3. cfa-cc is written in
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| 41 | C++.
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| 42 |
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| 43 | The compiler driver uses an installed version of gcc to handle all
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| 44 | aspects of the compilation process except for the Cforall->C translation.
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| 45 | Currently, only gcc 3.2 is supported.
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| 46 |
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| 47 | How is cfa-cc used?
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| 48 | -------------------
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| 49 | The compiler driver "cfa" accepts all of the arguments of gcc, and is
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| 50 | used in the same way. For example:
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| 51 |
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| 52 | cfa -c test.c
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| 53 | cfa test.o
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| 54 |
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| 55 | Cforall source files must end with '.c' in order to be compiled by the
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| 56 | compiler driver. In addition, the flag "-CFA" causes cfa to invoke the
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| 57 | preprocessor and translator and send the translator output to standard
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| 58 | output.
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| 59 |
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| 60 | In cases where the compiler driver is not useful (i.e., where gcc 3.2
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| 61 | is not available), it is still possible to invoke the translator
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| 62 | directly. The translator is installed by default as
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| 63 | /usr/local/lib/cfa-cpp. A typical invocation is:
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| 64 |
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| 65 | /usr/local/lib/cfa-cpp -cp infile outfile
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| 66 |
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| 67 | If outfile is omitted, output goes to standard output; if infile is
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| 68 | also omitted, input comes from standard input. Options to the
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| 69 | translator other than "-cp" will not produce valid C code and are only
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| 70 | useful for debugging the translator.
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| 71 |
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| 72 | How can C code be used with cfa-cc?
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| 73 | -----------------------------------
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| 74 | cfa-cc should be able to compile most ANSI C programs. It is also
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| 75 | possible to link against C libraries in most cases. Since Cforall
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| 76 | supports overloading, however, names used in Cforall code are
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| 77 | mangled in the output C code. This will cause linker failures when
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| 78 | the names refer to functions and objects in code compiled with
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| 79 | a standard C compiler. For this reason, it is necessary to enclose
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| 80 | the declarations of these functions and objects in extern "C" {}
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| 81 | blocks. For example:
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| 82 |
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| 83 | extern "C" {
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| 84 | #include <stdio.h>
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| 85 | #include <stdlib.h>
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| 86 | }
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| 87 |
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| 88 | The extern "C" turns off name mangling for functions and objects declared
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| 89 | within the block. As a result, it is not possible to overload their
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| 90 | names.
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| 91 |
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| 92 | It is our intention to have a transparent solution to this problem
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| 93 | in place for our first official release.
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| 94 |
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| 95 | What's wrong with cfa-cc?
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| 96 | -------------------------
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| 97 | The authors consider this software to be in an unstable state. It is
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| 98 | quite likely that there are many reasonable programs that will fail
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| 99 | to compile. We encourage users to report their experiences to
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| 100 | cforall@plg.uwaterloo.ca, but we make no promises regarding support.
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| 101 |
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| 102 | We have fixed most of the problems that we are aware of. There are
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| 103 | some exceptions:
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| 104 |
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| 105 | - initializers are poorly implemented; in particular,
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| 106 | file-scope initializers may result in the generation of invalid
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| 107 | C code
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| 108 |
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| 109 | - the ISO C99 designated initialization syntax '[n] = m' or
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| 110 | '.n = m' is not supported; use a colon in place of the equal sign
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| 111 |
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| 112 | - some legitimate programs will produce warnings from the C
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| 113 | compiler; these are harmless (in particular, the creation of
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| 114 | libcfa.a in the build process should cause four warnings from
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| 115 | gcc)
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| 116 |
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| 117 | - abstract types introduced using the keyword 'type' are not
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| 118 | implemented (although 'type' can be used to introduce type
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| 119 | parameters)
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| 120 |
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| 121 | - the implicit coercion of structure types to the type of their
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| 122 | first member is not implemented
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| 123 |
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| 124 | Who is responsible for cfa-cc?
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| 125 | ------------------------------
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| 126 | cfa-cc was written by Peter Buhr, Richard Bilson, and Rodolfo Esteves.
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| 127 | Questions and comments can be sent to cforall@plg.uwaterloo.ca.
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| 128 |
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| 129 | The Cforall project maintains a web page:
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| 130 |
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| 131 | http://plg.uwaterloo.ca/~cforall
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