2C(1)                                                       2C(1)

     NAME
          2c, 6c, 8c, kc, vc, zc - C compilers

     SYNOPSIS
          2c [ option ... ] [ name ... ]
          6c [ option ... ] [ name ... ]
          8c [ option ... ] [ name ... ]
          kc [ option ... ] [ name ... ]
          vc [ option ... ] [ name ... ]
          zc [ option ... ] [ name ... ]

     DESCRIPTION
          2c, 6c, 8c, kc, vc, and zc compile the named C files into
          MC68020, i960, i386, SPARC, MIPS, and Hobbit object files.
          The compilers handle most preprocessing directives them-
          selves; a complete preprocessor is available in cpp(1),
          which must be run separately.

          Let the first letter of the compiler name be O= 2, 6, 8, k,
          v, or z.  The output object files end in .O.  The letter is
          also the prefix of related programs: Oa is the assembler, Ol
          is the loader.  Associated with each compiler is a string
          objtype= 68020, 960, 386, sparc, mips, or hobbit.  Plan 9
          conventionally sets the $objtype environment variable to the
          objtype string appropriate to the current machine's type.
          Plan 9 also conventionally has /objtype directories, which
          contain among other things: include, for machine-dependent
          include files; lib, for public object code libraries; bin,
          for public programs; and mkfile, for preconditioning mk(1).

          The compiler options are:

          -o obj    Place output in file obj (allowed only if there is
                    just one input file).  Default is to take the last
                    element of the input pathname, strip any trailing
                    .c, and append .O.

          -w        Print warning messages about unused variables,
                    etc.

          -A        Complain about functions used without a new-style
                    ANSI C function prototype.  This option is on by
                    default.

          -B        Turn off the action of the -A flag.

          -Dname=def
          -Dname    Define the name to the preprocessor, as if by
                    `#define'.  If no definition is given, the name is
                    defined as `1'.

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     2C(1)                                                       2C(1)

          -Idir     `#include' files whose names do not begin with `/'
                    are always sought first in the directory of the
                    file argument, then in directories named in -I
                    options, then in /sys/include, and finally in
                    /$objtype/include.

          -O        Perform object code optimization.  This option is
                    on by default.

          -N        Turn off the action of the -O flag.

          -S        Print an assembly language version of the object
                    code on standard output as well as generating the
                    .O file.

          -sname    Print on standard output a listing of the fields
                    in structure or union name together with their
                    offsets and some type information.  This can be
                    used in conjunction with the debugger (see db(1)).

          The compilers support several extensions to ANSI C:

          -    A structure or union may contain unnamed substructures
               and subunions.  The fields of the substructures or sub-
               unions can then be used as if they were members of the
               parent structure or union (the resolution of a name
               conflict is unspecified).  When a pointer to the outer
               structure or union is used in a context that is only
               legal for the unnamed substructure, the compiler pro-
               motes the type and adjusts the pointer value to point
               at the substructure.

          -    A structure value can be formed with an expression such
               as
                   (struct S){v1, v2, v3}
               where the list elements are values for the fields of
               struct S.

          -    Array initializers can specify the indices of the array
               in square brackets, as
                   int a[] = { [3] 1, [10] 5 };
               which initializes the third and tenth elements of the
               eleven-element array a.

          -    A global variable can be dedicated to a register by
               declaring it extern register in all modules and
               libraries.

          -    A #pragma of the form
               #pragma   lib "libbio.a"
               records that the program needs to be loaded with file
               /$objtype/lib/libbio.a; such lines, typically placed in

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     2C(1)                                                       2C(1)

               library header files, obviate the -l option of the
               loaders.

     EXAMPLE
          For the 68020, produce a program prog from C files main.c
          and sub.c:

               2c -w main.c sub.c
               2l -o prog main.2 sub.2

     FILES
          /sys/include       system area for machine-independent
                             #include directives.
          /$objtype/include  system area for machine-dependent
                             #include directives.

     SEE ALSO
          2a(1), 2l(1), rl(1), mk(1), nm(1), db(1)

          Rob Pike, ``How to Use the Plan 9 C Compiler''

     BUGS
          The i960 compiler has been used only to program one I/O con-
          troller and is certainly buggy.

          Bitfields are not supported in zc.

          The preprocessor only handles `#define', `#include',
          `#undef', `#ifdef', `#line', and `#ifndef'.  For a full ANSI
          preprocessor, use cpp(1) on the files first.

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