2C(1) 2C(1)
NAME
0c, 1c, 2c, 4c, 5c, 6c, 7c, 8c, 9c, kc, qc, vc, xc - C
compilers
SYNOPSIS
2c [ option ... ] [ file ... ]
etc.
DESCRIPTION
These commands compile the named C files into object files
for the corresponding architecture. Associated with each
compiler is a string objtype:
0c spim little-endian MIPS 4000 family
1c 68000 Motorola MC68000
2c 68020 Motorola MC68020
4c mips2 big-endian MIPS 4000 family
5c arm ARM 7500
6c 960 Intel i960
7c alpha Digital Alpha APX
8c 386 Intel i386, i486, Pentium, etc.
9c 29000 AMD 29000 family
kc sparc Sun SPARC
qc power Power PC,
vc mips big-endian MIPS 3000 family
xc 3210 AT&T DSP 3210.
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= 0, 1, 2, 4,
5, 6, 7, 8, 9, k, q, v, or x. The output object files end
in .O. The letter is also the prefix of related programs:
Oa is the assembler, Ol is the loader. Plan 9 convention-
ally sets the $objtype environment variable to the objtype
string appropriate to the current machine's type. Plan 9
also conventionally has /objtype directories, which contain
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2C(1) 2C(1)
among other things: include, for machine-dependent include
files; lib, for public object code libraries; bin, for pub-
lic programs; and mkfile, for preconditioning mk(1).
The compiler options are:
-o obj Place output in file obj (allowed only if there is
just one input file). Default is to take the last
element of the input file name, strip any trailing
.c, and append .O.
-w Print warning messages about unused variables,
etc.
-B Accept functions without a new-style ANSI C func-
tion prototype. By default, the compilers reject
functions used without a defined prototype,
although ANSI C permits them.
-Dname=def
-Dname Define the name to the preprocessor, as if by
`#define'. If no definition is given, the name is
defined as `1'.
-F Enable type-checking of calls to print(2) and
other formatted print routines. See the discus-
sion of extensions, below.
-Idir An `#include' file whose name does not begin with
slash or is enclosed in double quotes is always
sought first in the directory of the file argu-
ment. If this fails, or the name is enclosed in
<>, it is then sought in directories named in -I
options, then in /sys/include, and finally in
/$objtype/include.
-N Suppress automatic registerization and optimiza-
tion.
-S Print an assembly language version of the object
code on standard output as well as generating the
.O file.
-V By default, the compilers are non-standardly lax
about type equality between void* values and other
pointers; this flag requires ANSI C conformance.
-p Invoke a standard ANSI C preprocessor before com-
piling.
-a Instead of compiling, print on standard output
acid functions (see acid(1)) for examining
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2C(1) 2C(1)
structures declared in the source files.
-aa Like -a except suppress information about struc-
tures declared in included header files.
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. If the unnamed structure or union
is of a type with a tag name specified by a typedef
statement, the unnamed structure or union can be
explicitly referenced by <struct variable>.<tagname>.
- 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.
- Structure initializers can specify the structure ele-
ment by using the name following a period, as
int struct { int x; int y; } s = { .y 1, .x 5 };
which initializes elements y and then x of the struc-
ture s. These forms also accept the new ANSI C nota-
tion, which includes an equal sign:
int a[] = { [3] = 1, [10] = 5 };
int struct { int x; int y; } s = { .y = 1, .x = 5 };
- 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
library header files, obviate the -l option of the
loaders. To help identify files in non-standard direc-
tories, within the file names in the #pragmas the
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2C(1) 2C(1)
string $M represents the name of the architecture
(e.g., mips) and $O represents its identifying charac-
ter (e.g., v).
- A #pragma of the form
#pragma varargck argpos error 2
tells the compiler that the second argument to error is
a print-like format string (see print(2)) that identi-
fies the handling of subsequent arguments. The #pragma
#pragma varargck type "s" char*
says that the format verb s processes an argument of
type char*. These #pragmas are used, if the -F option
is enabled, to type-check calls to print and other such
routines.
- The C++ comment (// to end of line) is accepted as well
as the normal convention of /* */.
- The compilers accept long long variables as a 64-bit
type. The standard header typedefs this to vlong.
Arithmetic on vlong values is usually emulated by a
run-time library.
EXAMPLE
For the 68020, produce a program prog from C files main.c
and sub.c:
2c -w main.c sub.c
2l -o prog main.2 sub.2
FILES
/sys/include system area for machine-independent
#include directives.
/$objtype/include system area for machine-dependent
#include directives.
SOURCE
/sys/src/cmd/cc machine-independent part
/sys/src/cmd/2c, etc. machine-dependent part
SEE ALSO
2a(1), 2l(1), cpp(1), mk(1), nm(1), pcc(1), db(1), acid(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.
The default preprocessor only handles `#define', `#include',
`#undef', `#ifdef', `#line', and `#ifndef'. For a full ANSI
preprocessor, use the p option.
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