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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