CC(1) CC(1)
NAME
cc - GNU project C Compiler
SYNOPSIS
cc [ options ] files
DESCRIPTION
Cc is a version of the GNU C compiler. It accepts a
dialect of ANSI C with extensions; this dialect is differ-
ent from the dialect used in 4.3 BSD and earlier distribu-
tions. The -traditional flag causes the compiler to
accept a dialect of extended Classic C, much like the C of
these earlier distributions. If you are not already
familiar with ANSI C and its new features, you will want
to build your software with -traditional.
DIFFERENCES
Most older C compiler flags are supported by cc. Three
that are not are: -go, to generate symbol tables for the
unsupported sdb debugger; -f, for single precision float-
ing point in expressions, which is now the default; and
-t, for alternate compiler passes.
The differences between ANSI C and Classic C dialects are
too numerous to describe here in detail. The following
quick summary is meant to make users aware of potential
subtle problems when converting Classic C code to ANSI C.
The most obvious change is the pervasive use of function
prototypes. Under the ANSI C dialect, the number and type
of arguments to C library functions are checked by the
compiler when standard header files are included; calls
that fail to match will yield errors. Argument type
checking using prototype declarations in header files is
meant to replace the old Unix lint(1) type-checking pro-
gram, which is not available on non-Unix systems. A sub-
tle consequence of adding prototype declarations is that
user code that inadvertently redefines a C library func-
tion may break; for example it is no longer possible to
write an abort function that takes different parameters or
returns a different value from the standard abort, when
including standard header files. Another issue with pro-
totypes is that functions that take different parameter
types no longer have the same type; function pointers now
differ by parameter types as well as return types. Vari-
able argument lists are handled differently; the old
varargs(3) package is obsolete, replaced by stdarg(3),
which unfortunately is not completely compatible. A sub-
tle change in type promotion can be confusing: small
unsigned types are now widened into signed types rather
than unsigned types. A similar problem can occur with the
sizeof operator, which now yields an unsigned type rather
than a signed type. One common problem is due to a change
in scoping: external declarations are now scoped to the
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block they occur in, so a declaration for (say) errno
inside one block will no longer declare it in all subse-
quent blocks. The syntax for braces in structure initial-
izations is now a bit stricter, and it is sometimes neces-
sary to add braces to please the compiler. Two very sub-
tle and sometimes very annoying features apply to constant
strings and to the longjmp(3) function. Constant strings
in the ANSI dialect are read-only; attempts to alter them
cause protection violations. This ANSI feature permits
the compiler to coalesce identical strings in the same
source file, and saves space when multiple copies of a
binary are running at the same time, since the read-only
part of a binary is sharable. The most common difficulty
with read-only strings lies with the use of the mktemp
function, which in the past often altered a constant
string argument. It is now necessary to copy a constant
string (for example, with strdup(3)) before it may be
altered. The longjmp function may now destroy any regis-
ter or stack variable in the function that made the corre-
sponding call to the setjmp function; to protect a local
variable, the new ANSI volatile modifier must be used.
This often leads to confusing situations upon `return'
from setjmp. The compiler has extended warning flags for
dealing with read-only strings and setjmp, but these are
not very effective. If your code has problems with any of
these ANSI features, you will probably want to use -tradi-
tional.
Even with -traditional, there are some differences between
this dialect of Classic C and the dialect supported on
older distributions.
There are at least two differences that are a consequence
of the fact that cc uses an ANSI C style grammar for both
traditional and ANSI modes. The old C dialect permitted a
typedef to replace a simple type in the idiom ``unsigned
type''; this cc treats such forms as syntax errors. The
old C dialect also permitted formal parameters to have the
same names as typedef types; the current dialect does not.
Some questionable or illegal practices that were supported
in the old C dialect are not supported by -traditional:
non-comment text at the end of a ``#include'' preprocessor
control line is an error, not ignored; compound assignment
operators must not contain white space, e.g. ``* ='' is
not the same as ``*=''; the last member declaration in a
structure or union must be terminated by a semicolon; it
is not possible to ``switch'' on function pointers; more
than one occurrence of ``#else'' at the same level in a
preprocessor ``#if'' clause is an error, not ignored.
Some truly ancient C practices are no longer supported.
The idiom of declaring an anonymous structure and using
its members to extract fields from other structures or
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even non-structures is illegal. Integers are not automat-
ically converted to pointers when they are dereferenced.
The -traditional dialect does not retain the so-called
``old-fashioned'' assignment operators (with the ``=''
preceding rather than following the operator) or initial-
izations (with no ``='' between initializer and initial-
izee).
WARNING
This rest of man page is an extract of the documentation
of the GNU C compiler and is limited to the meaning of the
options. It is not kept up to date. If you want to be
certain of the information below, check it in the manual
"Using and Porting GCC". Refer to the Info file gcc.info
or the DVI file gcc.dvi which are made from the Texinfo
source file gcc.texinfo.
The GNU C compiler uses a command syntax much like the
Unix C compiler. The cc program accepts options and file
names as operands. Multiple single-letter options may not
be grouped: -dr is very different from -d -r.
When you invoke GNU CC, it normally does preprocessing,
compilation, assembly and linking. File names which end
in .c are taken as C source to be preprocessed and com-
piled; file names ending in .i are taken as preprocessor
output to be compiled; compiler output files plus any
input files with names ending in .s are assembled; then
the resulting object files, plus any other input files,
are linked together to produce an executable.
Command options allow you to stop this process at an
intermediate stage. For example, the -c option says not
to run the linker. Then the output consists of object
files output by the assembler.
Other command options are passed on to one stage of pro-
cessing. Some options control the preprocessor and others
the compiler itself. Yet other options control the assem-
bler and linker; these are not documented here, but you
rarely need to use any of them.
OPTIONS
Here are the options to control the overall compilation
process, including those that say whether to link, whether
to assemble, and so on.
-o file
Place output in file file. This applies regardless
to whatever sort of output is being produced,
whether it be an executable file, an object file,
an assembler file or preprocessed C code.
If -o is not specified, the default is to put an
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executable file in a.out, the object file source.c
in source.o, an assembler file in source.s, and
preprocessed C on standard output.
-c Compile or assemble the source files, but do not
link. Produce object files with names made by
replacing .c or .s with .o at the end of the input
file names. Do nothing at all for object files
specified as input.
-S Compile into assembler code but do not assemble.
The assembler output file name is made by replacing
.c with .s at the end of the input file name. Do
nothing at all for assembler source files or object
files specified as input.
-E Run only the C preprocessor. Preprocess all the C
source files specified and output the results to
standard output.
-v Compiler driver program prints the commands it exe-
cutes as it runs the preprocessor, compiler proper,
assembler and linker. Some of these are directed
to print their own version numbers.
-pipe Use pipes rather than temporary files for communi-
cation between the various stages of compilation.
This fails to work on some systems where the assem-
bler is unable to read from a pipe; but the GNU
assembler has no trouble.
-Bprefix
Compiler driver program tries prefix as a prefix
for each program it tries to run. These programs
are cpp, cc1, as and ld.
For each subprogram to be run, the compiler driver
first tries the -B prefix, if any. If that name is
not found, or if -B was not specified, the driver
tries a standard prefix, which currently is
/usr/libexec/. If this does not result in a file
name that is found, the unmodified program name is
searched for using the directories specified in
your PATH environment variable.
You can get a similar result from the environment
variable GCCEXECPREFIX; if it is defined, its
value is used as a prefix in the same way. If both
the -B option and the GCCEXECPREFIX variable are
present, the -B option is used first and the envi-
ronment variable value second.
-bprefix
The argument prefix is used as a second prefix for
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the compiler executables and libraries. This pre-
fix is optional: the compiler tries each file first
with it, then without it. This prefix follows the
prefix specified with -B or the default prefixes.
Thus, -bvax- -Bcc/ in the presence of environment
variable GCCEXECPREFIX with definition /u/foo/
causes GNU CC to try the following file names for
the preprocessor executable:
cc/vax-cpp
cc/cpp
/u/foo/vax-cpp
/u/foo/cpp
/usr/libexec/vax-cpp
/usr/libexec/cpp
These options control the details of C compilation itself.
-ansi Support all ANSI standard C programs.
This turns off certain features of GNU C that are
incompatible with ANSI C, such as the asm, inline
and typeof keywords, and predefined macros such as
unix and vax that identify the type of system you
are using. It also enables the undesirable and
rarely used ANSI trigraph feature.
The alternate keywords asm, inline and
typeof continue to work despite -ansi. You
would not want to use them in an ANSI C program, of
course, but it useful to put them in header files
that might be included in compilations done with
-ansi. Alternate predefined macros such as
unix and vax are also available, with or
without -ansi.
The -ansi option does not cause non-ANSI programs
to be rejected gratuitously. For that, -pedantic
is required in addition to -ansi.
The macro STRICTANSI is predefined when the
-ansi option is used. Some header files may notice
this macro and refrain from declaring certain func-
tions or defining certain macros that the ANSI
standard doesn't call for; this is to avoid inter-
fering with any programs that might use these names
for other things.
-traditional
Attempt to support some aspects of traditional C
compilers. Specifically:
* All extern declarations take effect globally even
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if they are written inside of a function defini-
tion. This includes implicit declarations of func-
tions.
* The keywords typeof, inline, signed, const and
volatile are not recognized.
* Comparisons between pointers and integers are
always allowed.
* Integer types unsigned short and unsigned char pro-
mote to unsigned int.
* Out-of-range floating point literals are not an
error.
* All automatic variables not declared register are
preserved by longjmp(3C). Ordinarily, GNU C fol-
lows ANSI C: automatic variables not declared
volatile may be clobbered.
* In the preprocessor, comments convert to nothing at
all, rather than to a space. This allows tradi-
tional token concatenation.
* In the preprocessor, macro arguments are recognized
within string constants in a macro definition (and
their values are stringified, though without addi-
tional quote marks, when they appear in such a con-
text). The preprocessor always considers a string
constant to end at a newline.
* The predefined macro STDC is not defined when
you use -traditional, but GNUC is (since the
GNU extensions which GNUC indicates are not
affected by -traditional). If you need to write
header files that work differently depending on
whether -traditional is in use, by testing both of
these predefined macros you can distinguish four
situations: GNU C, traditional GNU C, other ANSI C
compilers, and other old C compilers.
-O Optimize. Optimizing compilation takes somewhat
more time, and a lot more memory for a large func-
tion.
Without -O, the compiler's goal is to reduce the
cost of compilation and to make debugging produce
the expected results. Statements are independent:
if you stop the program with a breakpoint between
statements, you can then assign a new value to any
variable or change the program counter to any other
statement in the function and get exactly the
results you would expect from the source code.
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Without -O, only variables declared register are
allocated in registers. The resulting compiled
code is a little worse than produced by PCC without
-O.
With -O, the compiler tries to reduce code size and
execution time.
Some of the -f options described below turn spe-
cific kinds of optimization on or off.
-g Produce debugging information in the operating sys-
tem's native format (for DBX or SDB). GDB also can
work with this debugging information.
Unlike most other C compilers, GNU CC allows you to
use -g with -O. The shortcuts taken by optimized
code may occasionally produce surprising results:
some variables you declared may not exist at all;
flow of control may briefly move where you did not
expect it; some statements may not be executed
because they compute constant results or their val-
ues were already at hand; some statements may exe-
cute in different places because they were moved
out of loops. Nevertheless it proves possible to
debug optimized output. This makes it reasonable
to use the optimizer for programs that might have
bugs.
-w Inhibit all warning messages.
-W Print extra warning messages for these events:
* An automatic variable is used without first being
initialized.
These warnings are possible only in optimizing com-
pilation, because they require data flow informa-
tion that is computed only when optimizing. If you
don't specify -O, you simply won't get these warn-
ings.
These warnings occur only for variables that are
candidates for register allocation. Therefore,
they do not occur for a variable that is declared
volatile, or whose address is taken, or whose size
is other than 1, 2, 4 or 8 bytes. Also, they do
not occur for structures, unions or arrays, even
when they are in registers.
Note that there may be no warning about a variable
that is used only to compute a value that itself is
never used, because such computations may be
deleted by data flow analysis before the warnings
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are printed.
These warnings are made optional because GNU CC is
not smart enough to see all the reasons why the
code might be correct despite appearing to have an
error. Here is one example of how this can happen:
{
int x;
switch (y)
{
case 1: x = 1;
break;
case 2: x = 4;
break;
case 3: x = 5;
}
foo (x);
}
If the value of y is always 1, 2 or 3, then x is
always initialized, but GNU CC doesn't know this.
Here is another common case:
{
int save_y;
if (change_y) save_y = y, y = new_y;
...
if (change_y) y = save_y;
}
This has no bug because savey is used only if it
is set.
Some spurious warnings can be avoided if you
declare as volatile all the functions you use that
never return.
* A nonvolatile automatic variable might be changed
by a call to longjmp(3C). These warnings as well
are possible only in optimizing compilation.
The compiler sees only the calls to setjmp(3C). It
cannot know where longjmp(3C) will be called; in
fact, a signal handler could call it at any point
in the code. As a result, you may get a warning
even when there is in fact no problem because
longjmp(3C) cannot in fact be called at the place
which would cause a problem.
* A function can return either with or without a
value. (Falling off the end of the function body
is considered returning without a value.) For
example, this function would evoke such a warning:
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foo (a)
{
if (a > 0)
return a;
}
Spurious warnings can occur because GNU CC does not
realize that certain functions (including abort(3C)
and longjmp(3C)) will never return.
* An expression-statement contains no side effects.
In the future, other useful warnings may also be
enabled by this option.
-Wimplicit
Warn whenever a function is implicitly declared.
-Wreturn-type
Warn whenever a function is defined with a return-
type that defaults to int. Also warn about any
return statement with no return-value in a function
whose return-type is not void.
-Wunused
Warn whenever a local variable is unused aside from
its declaration, and whenever a function is
declared static but never defined.
-Wswitch
Warn whenever a switch statement has an index of
enumeral type and lacks a case for one or more of
the named codes of that enumeration. (The presence
of a default label prevents this warning.) case
labels outside the enumeration range also provoke
warnings when this option is used.
-Wcomment
Warn whenever a comment-start sequence /* appears
in a comment.
-Wtrigraphs
Warn if any trigraphs are encountered (assuming
they are enabled).
-Wall All of the above -W options combined. These are
all the options which pertain to usage that we do
not recommend and that we believe is always easy to
avoid, even in conjunction with macros.
The other -W... options below are not implied by
-Wall because certain kinds of useful macros are
almost impossible to write without causing those
warnings.
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-Wshadow
Warn whenever a local variable shadows another
local variable.
-Wid-clash-len
Warn whenever two distinct identifiers match in the
first len characters. This may help you prepare a
program that will compile with certain obsolete,
brain-damaged compilers.
-Wpointer-arith
Warn about anything that depends on the size of a
function type or of void. GNU C assigns these
types a size of 1, for convenience in calculations
with void * pointers and pointers to functions.
-Wcast-qual
Warn whenever a pointer is cast so as to remove a
type qualifier from the target type. For example,
warn if a const char * is cast to an ordinary char
*.
-Wwrite-strings
Give string constants the type const char[length]
so that copying the address of one into a non-const
char * pointer will get a warning. These warnings
will help you find at compile time code that can
try to write into a string constant, but only if
you have been very careful about using const in
declarations and prototypes. Otherwise, it will
just be a nuisance; this is why we did not make
-Wall request these warnings.
-p Generate extra code to write profile information
suitable for the analysis program prof(1).
-pg Generate extra code to write profile information
suitable for the analysis program gprof(1).
-a Generate extra code to write profile information
for basic blocks, suitable for the analysis program
tcov(1). Eventually GNU gprof(1) should be
extended to process this data.
-llibrary
Search a standard list of directories for a library
named library, which is actually a file named lib-
library.a. The linker uses this file as if it had
been specified precisely by name.
The directories searched include several standard
system directories plus any that you specify with
-L.
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Normally the files found this way are library
files--archive files whose members are object
files. The linker handles an archive file by scan-
ning through it for members which define symbols
that have so far been referenced but not defined.
But if the file that is found is an ordinary object
file, it is linked in the usual fashion. The only
difference between using an -l option and specify-
ing a file name is that -l searches several direc-
tories.
-Ldir Add directory dir to the list of directories to be
searched for -l.
-nostdlib
Don't use the standard system libraries and startup
files when linking. Only the files you specify
(plus gnulib) will be passed to the linker.
-mmachinespec
Machine-dependent option specifying something about
the type of target machine. These options are
defined by the macro TARGETSWITCHES in the machine
description. The default for the options is also
defined by that macro, which enables you to change
the defaults.
These are the -m options defined in the 68000
machine description:
-m68020
-mc68020
Generate output for a 68020 (rather than a
68000). This is the default if you use the
unmodified sources.
-m68000
-mc68000
Generate output for a 68000 (rather than a
68020).
-m68881
Generate output containing 68881 instructions
for floating point. This is the default if
you use the unmodified sources.
-mfpa
Generate output containing Sun FPA instruc-
tions for floating point.
-msoft-float
Generate output containing library calls for
floating point.
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-mshort
Consider type int to be 16 bits wide, like
short int.
-mnobitfield
Do not use the bit-field instructions.
-m68000 implies -mnobitfield.
-mbitfield
Do use the bit-field instructions. -m68020
implies -mbitfield. This is the default if
you use the unmodified sources.
-mrtd
Use a different function-calling convention,
in which functions that take a fixed number of
arguments return with the rtd instruction,
which pops their arguments while returning.
This saves one instruction in the caller since
there is no need to pop the arguments there.
This calling convention is incompatible with
the one normally used on Unix, so you cannot
use it if you need to call libraries compiled
with the Unix compiler.
Also, you must provide function prototypes for
all functions that take variable numbers of
arguments (including printf(3S)); otherwise
incorrect code will be generated for calls to
those functions.
In addition, seriously incorrect code will
result if you call a function with too many
arguments. (Normally, extra arguments are
harmlessly ignored.)
The rtd instruction is supported by the 68010
and 68020 processors, but not by the 68000.
These -m options are defined in the Vax machine
description:
-munix
Do not output certain jump instructions
(aobleq and so on) that the Unix assembler for
the Vax cannot handle across long ranges.
-mgnu
Do output those jump instructions, on the
assumption that you will assemble with the GNU
assembler.
-mg
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Output code for g-format floating point num-
bers instead of d-format.
These -m switches are supported on the Sparc:
-mfpu
Generate output containing floating point
instructions. This is the default if you use
the unmodified sources.
-msoft-float
Generate output containing library calls for
floating point.
-mno-epilogue
Generate separate return instructions for
return statements. This has both advantages
and disadvantages; I don't recall what they
are.
These -m options are defined in the Convex machine
description:
-mc1
Generate output for a C1. This is the default
when the compiler is configured for a C1.
-mc2
Generate output for a C2. This is the default
when the compiler is configured for a C2.
-margcount
Generate code which puts an argument count in
the word preceding each argument list. Some
nonportable Convex and Vax programs need this
word. (Debuggers don't; this info is in the
symbol table.)
-mnoargcount
Omit the argument count word. This is the
default if you use the unmodified sources.
-fflag Specify machine-independent flags. Most flags have
both positive and negative forms; the negative form
of -ffoo would be -fno-foo. In the table below,
only one of the forms is listed--the one which is
not the default. You can figure out the other form
by either removing no- or adding it.
-fpcc-struct-return
Use the same convention for returning struct and
union values that is used by the usual C compiler
on your system. This convention is less efficient
for small structures, and on many machines it fails
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to be reentrant; but it has the advantage of allow-
ing intercallability between GCC-compiled code and
PCC-compiled code.
-ffloat-store
Do not store floating-point variables in registers.
This prevents undesirable excess precision on
machines such as the 68000 where the floating reg-
isters (of the 68881) keep more precision than a
double is supposed to have.
For most programs, the excess precision does only
good, but a few programs rely on the precise defi-
nition of IEEE floating point. Use -ffloat-store
for such programs.
-fno-asm
Do not recognize asm, inline or typeof as a key-
word. These words may then be used as identifiers.
You can use asm, inline and typeof
instead.
-fno-defer-pop
Always pop the arguments to each function call as
soon as that function returns. Normally the com-
piler (when optimizing) lets arguments accumulate
on the stack for several function calls and pops
them all at once.
-fstrength-reduce
Perform the optimizations of loop strength reduc-
tion and elimination of iteration variables.
-fcombine-regs
Allow the combine pass to combine an instruction
that copies one register into another. This might
or might not produce better code when used in addi-
tion to -O. I am interested in hearing about the
difference this makes.
-fforce-mem
Force memory operands to be copied into registers
before doing arithmetic on them. This may produce
better code by making all memory references poten-
tial common subexpressions. When they are not com-
mon subexpressions, instruction combination should
eliminate the separate register-load. I am inter-
ested in hearing about the difference this makes.
-fforce-addr
Force memory address constants to be copied into
registers before doing arithmetic on them. This
may produce better code just as -fforce-mem may. I
am interested in hearing about the difference this
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makes.
-fomit-frame-pointer
Don't keep the frame pointer in a register for
functions that don't need one. This avoids the
instructions to save, set up and restore frame
pointers; it also makes an extra register available
in many functions. It also makes debugging impos-
sible.
On some machines, such as the Vax, this flag has no
effect, because the standard calling sequence auto-
matically handles the frame pointer and nothing is
saved by pretending it doesn't exist. The machine-
description macro FRAMEPOINTERREQUIRED controls
whether a target machine supports this flag.
-finline-functions
Integrate all simple functions into their callers.
The compiler heuristically decides which functions
are simple enough to be worth integrating in this
way.
If all calls to a given function are integrated,
and the function is declared static, then the func-
tion is normally not output as assembler code in
its own right.
-fcaller-saves
Enable values to be allocated in registers that
will be clobbered by function calls, by emitting
extra instructions to save and restore the regis-
ters around such calls. Such allocation is done
only when it seems to result in better code than
would otherwise be produced.
This option is enabled by default on certain
machines, usually those which have no call-
preserved registers to use instead.
-fkeep-inline-functions
Even if all calls to a given function are inte-
grated, and the function is declared static, never-
theless output a separate run-time callable version
of the function.
-fwritable-strings
Store string constants in the writable data segment
and don't uniquize them. This is for compatibility
with old programs which assume they can write into
string constants. Writing into string constants is
a very bad idea; constants should be constant.
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-fcond-mismatch
Allow conditional expressions with mismatched types
in the second and third arguments. The value of
such an expression is void.
-fno-function-cse
Do not put function addresses in registers; make
each instruction that calls a constant function
contain the function's address explicitly.
This option results in less efficient code, but
some strange hacks that alter the assembler output
may be confused by the optimizations performed when
this option is not used.
-fvolatile
Consider all memory references through pointers to
be volatile.
-fshared-data
Requests that the data and non-const variables of
this compilation be shared data rather than private
data. The distinction makes sense only on certain
operating systems, where shared data is shared
between processes running the same program, while
private data exists in one copy per process.
-funsigned-char
Let the type char be the unsigned, like unsigned
char.
Each kind of machine has a default for what char
should be. It is either like unsigned char by
default or like signed char by default. (Actually,
at present, the default is always signed.)
The type char is always a distinct type from either
signed char or unsigned char, even though its
behavior is always just like one of those two.
Note that this is equivalent to -fno-signed-char,
which is the negative form of -fsigned-char.
-fsigned-char
Let the type char be signed, like signed char.
Note that this is equivalent to -fno-unsigned-char,
which is the negative form of -funsigned-char.
-fdelayed-branch
If supported for the target machine, attempt to
reorder instructions to exploit instruction slots
available after delayed branch instructions.
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-ffixed-reg
Treat the register named reg as a fixed register;
generated code should never refer to it (except
perhaps as a stack pointer, frame pointer or in
some other fixed role).
reg must be the name of a register. The register
names accepted are machine-specific and are defined
in the REGISTERNAMES macro in the machine descrip-
tion macro file.
This flag does not have a negative form, because it
specifies a three-way choice.
-fcall-used-reg
Treat the register named reg as an allocatable reg-
ister that is clobbered by function calls. It may
be allocated for temporaries or variables that do
not live across a call. Functions compiled this
way will not save and restore the register REG.
Use of this flag for a register that has a fixed
pervasive role in the machine's execution model,
such as the stack pointer or frame pointer, will
produce disastrous results.
This flag does not have a negative form, because it
specifies a three-way choice.
-fcall-saved-reg
Treat the register named reg as an allocatable reg-
ister saved by functions. It may be allocated even
for temporaries or variables that live across a
call. Functions compiled this way will save and
restore the register reg if they use it.
Use of this flag for a register that has a fixed
pervasive role in the machine's execution model,
such as the stack pointer or frame pointer, will
produce disastrous results.
A different sort of disaster will result from the
use of this flag for a register in which function
values may be returned.
This flag does not have a negative form, because it
specifies a three-way choice.
-dletters
Says to make debugging dumps at times specified by
letters. Here are the possible letters:
r
Dump after RTL generation.
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j
Dump after first jump optimization.
J
Dump after last jump optimization.
s
Dump after CSE (including the jump optimiza-
tion that sometimes follows CSE).
L
Dump after loop optimization.
f
Dump after flow analysis.
c
Dump after instruction combination.
l
Dump after local register allocation.
g
Dump after global register allocation.
d
Dump after delayed branch scheduling.
m
Print statistics on memory usage, at the end
of the run.
-pedantic
Issue all the warnings demanded by strict ANSI
standard C; reject all programs that use forbidden
extensions.
Valid ANSI standard C programs should compile prop-
erly with or without this option (though a rare few
will require -ansi). However, without this option,
certain GNU extensions and traditional C features
are supported as well. With this option, they are
rejected. There is no reason to use this option;
it exists only to satisfy pedants.
-pedantic does not cause warning messages for use
of the alternate keywords whose names begin and end
with .
-static
On Suns running version 4, this prevents linking
with the shared libraries. (-g has the same
effect.)
These options control the C preprocessor, which is run on
each C source file before actual compilation. If you use
the `-E' option, nothing is done except C preprocessing.
Some of these options make sense only together with `-E'
because they request preprocessor output that is not suit-
able for actual compilation.
-C Tell the preprocessor not to discard comments.
Used with the -E option.
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-Idir Search directory dir for include files.
-I- Any directories specified with -I options before
the -I- option are searched only for the case of
#include "file"; they are not searched for #include
<file>.
If additional directories are specified with -I
options after the -I-, these directories are
searched for all #include directives. (Ordinarily
all -I directories are used this way.)
In addition, the -I- option inhibits the use of the
current directory as the first search directory for
#include "file". Therefore, the current directory
is searched only if it is requested explicitly with
-I.. Specifying both -I- and -I. allows you to
control precisely which directories are searched
before the current one and which are searched
after.
-nostdinc
Do not search the standard system directories for
header files. Only the directories you have speci-
fied with -I options (and the current directory, if
appropriate) are searched.
Between -nostdinc and -I-, you can eliminate all
directories from the search path except those you
specify.
-M Tell the preprocessor to output a rule suitable for
make(1) describing the dependencies of each source
file. For each source file, the preprocessor out-
puts one make-rule whose target is the object file
name for that source file and whose dependencies
are all the files #included in it. This rule may
be a single line or may be continued with \-newline
if it is long.
-M implies -E.
-MM Like -M but the output mentions only the user-
header files included with #include "file". System
header files included with #include <file> are
omitted.
-MM implies -E.
-Dmacro
Define macro macro with the empty string as its
definition.
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-Dmacro=defn
Define macro macro as defn.
-Umacro
Undefine macro macro.
-trigraphs
Support ANSI C trigraphs. You don't want to know
about this brain-damage. The -ansi option also has
this effect.
FILES
file.c C source file
file.s assembly language file
file.o object file
a.out link edited output
/tmp/cc* temporary files
/usr/libexec/cpp preprocessor
/usr/libexec/cc1 compiler
/usr/lib/libgnulib.a library needed by GCC on some
machines
/usr/lib/crt0.o start-up routine
/usr/lib/libc.a standard C library, see intro(3)
/usr/include standard directory for #include files
SEE ALSO
as(1), ld(1), gdb(1)
BUGS
This version of GCC is obsolete.
Function prototypes don't entirely make up for the loss of
lint(1). Lint did type-checking automatically, while pro-
totypes must be assembled and declared by hand. Lint
could find type problems in files which failed to include
the proper headers. Alas, lint will never be replaced, so
we must learn to write prototypes.
COPYING
Copyright (c) 1988 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim
copies of this manual provided the copyright notice and
this permission notice are preserved on all copies.
Permission is granted to copy and distribute modified ver-
sions of this manual under the conditions for verbatim
copying, provided that the entire resulting derived work
is distributed under the terms of a permission notice
identical to this one.
Permission is granted to copy and distribute translations
of this manual into another language, under the above con-
ditions for modified versions, except that this permission
Version 1.40 May 9, 1991 20
CC(1) CC(1)
notice may be included in translations approved by the
Free Software Foundation instead of in the original
English.
AUTHORS
See the GNU CC Manual for the contributors to GNU CC.
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