@c Copyright (C) 1988, 1989, 1992, 1993 Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.

@c The text of this file appears in the file INSTALL
@c in the GCC distribution, as well as in the GCC manual.

@ifclear INSTALLONLY
@node Installation
@chapter Installing GNU CC
@end ifclear
@cindex installing GNU CC

Here is the procedure for installing GNU CC on a Unix system.

@menu
* Other Dir::     Compiling in a separate directory (not where the source is).
* Cross-Compiler::   Building and installing a cross-compiler.
* PA Install::    See below for installation on the HP Precision Architecture.
* Sun Install::   See below for installation on the Sun.
* 3b1 Install::   See below for installation on the 3b1.
* Unos Install::  See below for installation on Unos (from CRDS).
* VMS Install::   See below for installation on VMS.
* WE32K Install:: See below for installation on the 3b* aside from the 3b1.
* MIPS Install::  See below for installation on the MIPS Architecture.
* Collect2::	  How @code{collect2} works; how it finds @code{ld}.
@end menu
@iftex
See below for VMS systems, and modified procedures needed on other
systems including HP, Sun, 3b1, SCO Unix and Unos.  The following section
says how to compile in a separate directory on Unix; here we assume you
compile in the same directory that contains the source files.
@end iftex

@enumerate
@item
If you have built GNU CC previously in the same directory for a
different target machine, do @samp{make distclean} to delete all files
that might be invalid.  One of the files this deletes is
@file{Makefile}; if @samp{make distclean} complains that @file{Makefile}
does not exist, it probably means that the directory is already suitably
clean.

@item
On a System V release 4 system, make sure @file{/usr/bin} precedes
@file{/usr/ucb} in @code{PATH}.  The @code{cc} command in
@file{/usr/ucb} uses libraries which have bugs.

@item
Specify the host and target machine configurations.  You do this by
running the file @file{configure} with appropriate arguments.

If you are building a compiler to produce code for the machine it runs
on, specify just one machine type.  Use the @samp{--target} option; the
host type will default to be the same as the target.  (For information
on building a cross-compiler, see @ref{Cross-Compiler}.)  The command
looks like this:

@smallexample
configure --target=sparc-sun-sunos4.1
@end smallexample

A configuration name may be canonical or it may be more or less
abbreviated.

A canonical configuration name has three parts, separated by dashes.
It looks like this: @samp{@var{cpu}-@var{company}-@var{system}}.
(The three parts may themselves contain dashes; @file{configure}
can figure out which dashes serve which purpose.)  For example,
@samp{m68k-sun-sunos4.1} specifies a Sun 3.

You can also replace parts of the configuration by nicknames or aliases.
For example, @samp{sun3} stands for @samp{m68k-sun}, so
@samp{sun3-sunos4.1} is another way to specify a Sun 3.  You can also
use simply @samp{sun3-sunos}, since the version of SunOS is assumed by
default to be version 4.  @samp{sun3-bsd} also works, since
@file{configure} knows that the only BSD variant on a Sun 3 is SunOS.

You can specify a version number after any of the system types, and some
of the CPU types.  In most cases, the version is irrelevant, and will be
ignored.  So you might as well specify the version if you know it.

Here are the possible CPU types:

@quotation
@c gmicro, alliant, spur and tahoe omitted since they don't work.
a29k, alpha, arm, c@var{n}, clipper, elxsi, h8300, hppa1.0, hppa1.1,
i386, i860, i960, m68000, m68k, m88k, mips,
ns32k, pyramid, romp, rs6000, sh, sparc, sparclite, vax, we32k.
@end quotation

Here are the recognized company names.  As you can see, customary
abbreviations are used rather than the longer official names.

@c What should be done about merlin, tek*, dolphin?
@quotation
alliant, altos, apollo, att, bull,
cbm, convergent, convex, crds, dec, dg, dolphin,
elxsi, encore, harris, hitachi, hp, ibm, intergraph, isi,
mips, motorola, ncr, next, ns, omron, plexus,
sequent, sgi, sony, sun, tti, unicom.
@end quotation

The company name is meaningful only to disambiguate when the rest of
the information supplied is insufficient.  You can omit it, writing
just @samp{@var{cpu}-@var{system}}, if it is not needed.  For example,
@samp{vax-ultrix4.2} is equivalent to @samp{vax-dec-ultrix4.2}.

Here is a list of system types:

@quotation
aix, acis, aos, bsd, clix, ctix, dgux, dynix,
genix, hpux, isc, linux, luna, mach,
minix, newsos, osf, osfrose, riscos,
sco, solaris, sunos, sysv, ultrix, unos, vms.
@end quotation

@noindent
You can omit the system type; then @file{configure} guesses the
operating system from the CPU and company.

You can add a version number to the system type; this may or may not
make a difference.  For example, you can write @samp{bsd4.3} or
@samp{bsd4.4} to distinguish versions of BSD.  In practice, the version
number is most needed for @samp{sysv3} and @samp{sysv4}, which are often
treated differently.

If you specify an impossible combination such as @samp{i860-dg-vms},
then you may get an error message from @file{configure}, or it may
ignore part of the information and do the best it can with the rest.
@file{configure} always prints the canonical name for the alternative
that it used.

Often a particular model of machine has a name.  Many machine names are
recognized as aliases for CPU/company combinations.  Thus, the machine
name @samp{sun3}, mentioned above, is an alias for @samp{m68k-sun}.
Sometimes we accept a company name as a machine name, when the name is
popularly used for a particular machine.  Here is a table of the known
machine names:

@quotation
3300, 3b1, 3b@var{n}, 7300, altos3068, altos,
apollo68, att-7300, balance,
convex-c@var{n}, crds, decstation-3100,
decstation, delta, encore,
fx2800, gmicro, hp7@var{nn}, hp8@var{nn},
hp9k2@var{nn}, hp9k3@var{nn}, hp9k7@var{nn},
hp9k8@var{nn}, iris4d, iris, isi68,
m3230, magnum, merlin, miniframe,
mmax, news-3600, news800, news, next,
pbd, pc532, pmax, ps2, risc-news,
rtpc, sun2, sun386i, sun386, sun3,
sun4, symmetry, tower-32, tower.
@end quotation 

@noindent
Remember that a machine name specifies both the cpu type and the company
name.

There are four additional options you can specify independently to 
describe variant hardware and software configurations.  These are
@samp{--with-gnu-as}, @samp{--with-gnu-ld}, @samp{--with-stabs} and
@samp{--nfp}.

@table @samp
@item --with-gnu-as
On certain systems, you must specify whether you want GNU CC to work
with the usual compilation tools or with the GNU compilation tools
(including GAS).  Use the @samp{--with-gnu-as} argument when you run
@file{configure}, if you want to use the GNU tools.  (Specify
@samp{--with-gnu-ld} as well, since on these systems GAS works only with
the GNU linker.)  The systems where this makes a difference are
@samp{i386-@var{anything}-sysv}, @samp{i860-@var{anything}-bsd},
@samp{m68k-hp-hpux}, @samp{m68k-sony-bsd}, @samp{m68k-altos-sysv},
@samp{m68000-hp-hpux}, @samp{m68000-att-sysv}, and
@samp{mips-@var{any}}).  On any other system, @samp{--with-gnu-as} has
no effect.

@c the above needs some serious help.. rearrange the systems names, or
@c something.. :-( --mew

@item --with-gnu-ld
Specify the option @samp{--with-gnu-ld} if you plan to use the GNU
linker.  This inhibits the installation of @code{collect2}, a program
which otherwise serves as a front-end for the system's linker on most
configurations.

@item --with-stabs
On MIPS based systems, you must specify whether you want GNU CC to
create the normal ECOFF debugging format, or to use BSD-style stabs
passed through the ECOFF symbol table.  The normal ECOFF debug format
cannot fully handle languages other than C.  BSD stabs format can handle
other languages, but it only works with the GNU debugger GDB.

Normally, GNU CC uses the ECOFF debugging format by default; if you
prefer BSD stabs, specify @samp{--with-stabs} when you configure GNU
CC.

No matter which default you choose when you configure GNU CC, the user
can use the @samp{-gcoff} and @samp{-gstabs+} options to specify explicitly
the debug format for a particular compilation.

@item --nfp
On certain systems, you must specify whether the machine has a floating
point unit.  These systems are @samp{m68k-sun-sunos@var{n}} and
@samp{m68k-isi-bsd}.  On any other system, @samp{--nfp} currently has no
effect, though perhaps there are other systems where it could usefully
make a difference.
@end table

If you want to install your own homemade configuration files, you can
use @samp{local} as the company name to access them.  If you use 
configuration @samp{@var{cpu}-local}, the configuration name
without the cpu prefix 
is used to form the configuration file names.

Thus, if you specify @samp{m68k-local}, then the files
@file{m68k/local.md}, @file{m68k/local.h}, @file{m68k/local.c},
@file{m68k/xm-local.h}, @file{m68k/t-local}, and @file{m68k/x-local}
will be used.

Here is a list of configurations that have special treatment or special
things you must know:

@table @samp
@item alpha-*-osf1
Systems using processors that implement the DEC Alpha architecture and
are running the OSF/1 operating system, for example the DEC Alpha AXP
systems.  (VMS on the Alpha is not currently supported by GNU CC.)

GNU CC writes a @samp{.verstamp} directive to the assembler output file
unless it is built as a cross-compiler.  It gets the version to use from
the file @file{/usr/include/stamp.h}.  If you install a new version of
OSF/1, you should rebuild GCC to pick up the new version stamp.

Note that since the Alpha is a 64-bit architecture, cross-compilers
from 32-bit machines will not generate as efficient code as that
generated when the compiler is running on a 64-bit machine because many
optimizations that depend on being able to represent a word on the
target in an integral value on the host cannot be performed.
Building cross-compilers for 32-bit machines that run on the Alpha
has not been tested and may not work properly.

@item a29k
AMD Am29K-family processors.  These are normally used in embedded
applications.  There are no standard Unix configurations.
This configuration
corresponds to AMD's standard calling sequence and binary interface
and is compatible with other 29K tools.  

You may need to make a variant of the file @file{a29k.h} for your
particular configuration.

@item a29k-*-bsd
AMD Am29050 used in a system running a variant of BSD Unix.

@item elxsi-elxsi-bsd
The Elxsi's C compiler has known limitations that prevent it from
compiling GNU C.  Please contact @code{mrs@@cygnus.com} for more details.

@ignore
@item fx80
Alliant FX/8 computer.  Note that the standard installed C compiler in
Concentrix 5.0 has a bug which prevent it from compiling GNU CC
correctly.  You can patch the compiler bug as follows:

@smallexample
cp /bin/pcc ./pcc
adb -w ./pcc - << EOF
15f6?w 6610
EOF
@end smallexample

Then you must use the @samp{-ip12} option when compiling GNU CC
with the patched compiler, as shown here:

@smallexample
make CC="./pcc -ip12" CFLAGS=-w
@end smallexample

Note also that Alliant's version of DBX does not manage to work with the
output from GNU CC.
@end ignore

@item i386-*-sco
Compilation with RCC is recommended.

@item i386-ibm-aix
You need to use GAS version 2.1 or later, and and LD from
GNU binutils version 2.2 or later.

@item i386-sequent
Go to the Berkeley universe before compiling.  In addition, you probably
need to create a file named @file{string.h} containing just one line:
@samp{#include <strings.h>}.

@item i386-sun-sunos4
You may find that you need another version of GNU CC to begin
bootstrapping with, since the current version when built with the
system's own compiler seems to get an infinite loop compiling part of
@file{libgcc2.c}.  GNU CC version 2 compiled with GNU CC (any version)
seems not to have this problem.

@item m68000-att
AT&T 3b1, a.k.a. 7300 PC.  Special procedures are needed to compile GNU
CC with this machine's standard C compiler, due to bugs in that
compiler.  @xref{3b1 Install}.  You can bootstrap it more easily with
previous versions of GNU CC if you have them.

@item m68000-hp-bsd
HP 9000 series 200 running BSD.  Note that the C compiler that comes
with this system cannot compile GNU CC; contact @code{law@@cs.utah.edu}
to get binaries of GNU CC for bootstrapping.

@item m68k-altos
Altos 3068.  You must use the GNU assembler, linker and debugger.
Also, you must fix a kernel bug.  Details in the file @file{README.ALTOS}.

@item m68k-hp-hpux
HP 9000 series 300 or 400 running HP-UX.  HP-UX version 8.0 has a bug in
the assembler that prevents compilation of GNU CC.  To fix it, get patch
PHCO_0800 from HP.

In addition, @samp{--gas} does not currently work with this
configuration.  Changes in HP-UX have broken the library conversion tool
and the linker.

@item m68k-sun
Sun 3.  We do not provide a configuration file to use the Sun FPA by
default, because programs that establish signal handlers for floating
point traps inherently cannot work with the FPA.

@item m88k-svr3
Motorola m88k running the AT&T/Unisoft/Motorola V.3 reference port.
These systems tend to use the Green Hills C, revision 1.8.5, as the
standard C compiler.  There are apparently bugs in this compiler that
result in object files differences between stage 2 and stage 3.  If this
happens, make the stage 4 compiler and compare it to the stage 3
compiler.  If the stage 3 and stage 4 object files are identical, this
suggests a problem with the standard C compiler.  It is best, however,
to use an older version of GNU CC for bootstrapping.

@item m88k-dgux
Motorola m88k running DG/UX.  To build native or cross compilers on
DG/UX, you must first change to the 88open BCS software development
environment.  This is done by issuing this command:

@smallexample
eval `sde-target m88kbcs`
@end smallexample

@item m88k-tektronix-sysv3
Tektronix XD88 running UTekV 3.2e.  Do not turn on
optimization while building stage1 if you bootstrap with
the buggy Green Hills compiler.  Also, The bundled LAI
System V NFS is buggy so if you build in an NFS mounted
directory, start from a fresh reboot, or avoid NFS all together.
Otherwise you may have trouble getting clean comparisons
between stages.

@item mips-mips-bsd
MIPS machines running the MIPS operating system in BSD mode.  It's
possible that some old versions of the system lack the functions
@code{memcpy}, @code{memcmp}, and @code{memset}.  If your system lacks
these, you must remove or undo the definition of
@code{TARGET_MEM_FUNCTIONS} in @file{mips-bsd.h}.

@item mips-sgi-*
Silicon Graphics MIPS machines running IRIX.  In order to compile
GCC on an SGI the "c.hdr.lib" option must be installed from the
CD-ROM supplied from Silicon Graphics.  This is found on the 2nd
CD in release 4.0.1.

@item mips-sony-sysv
Sony MIPS NEWS.  This works in NEWSOS 5.0.1, but not in 5.0.2 (which
uses ELF instead of COFF).  Support for 5.0.2 will probably be provided
soon by volunteers.  In particular, the linker does not like the
code generated by GCC when shared libraries are linked in.

@item ns32k-encore
Encore ns32000 system.  Encore systems are supported only under BSD.

@item ns32k-*-genix
National Semiconductor ns32000 system.  Genix has bugs in @code{alloca}
and @code{malloc}; you must get the compiled versions of these from GNU
Emacs.

@item ns32k-sequent
Go to the Berkeley universe before compiling.  In addition, you probably
need to create a file named @file{string.h} containing just one line:
@samp{#include <strings.h>}.

@item ns32k-utek
UTEK ns32000 system (``merlin'').  The C compiler that comes with this
system cannot compile GNU CC; contact @samp{tektronix!reed!mason} to get
binaries of GNU CC for bootstrapping.

@item romp-*-aos
@itemx romp-*-mach
The only operating systems supported for the IBM RT PC are AOS and
MACH.  GNU CC does not support AIX running on the RT.  We recommend you
compile GNU CC with an earlier version of itself; if you compile GNU CC
with @code{hc}, the Metaware compiler, it will work, but you will get
mismatches between the stage 2 and stage 3 compilers in various files.
These errors are minor differences in some floating-point constants and
can be safely ignored; the stage 3 compiler is correct.

@item rs6000-*-aix
@strong{Read the file @file{README.RS6000} for information on how to get
a fix for problems in the IBM assembler that interfere with GNU CC.} You
must either obtain the new assembler or avoid using the @samp{-g}
switch.  Note that @file{Makefile.in} uses @samp{-g} by default when
compiling @file{libgcc2.c}.

@item vax-dec-ultrix
Don't try compiling with Vax C (@code{vcc}).  It produces incorrect code
in some cases (for example, when @code{alloca} is used).

Meanwhile, compiling @file{cp-parse.c} with pcc does not work because of
an internal table size limitation in that compiler.  To avoid this
problem, compile just the GNU C compiler first, and use it to recompile 
building all the languages that you want to run.
@end table

Here we spell out what files will be set up by @code{configure}.  Normally
you need not be concerned with these files.

@itemize @bullet
@item
@ifset INTERNALS
A symbolic link named @file{config.h} is made to the top-level config
file for the machine you will run the compiler on (@pxref{Config}).
This file is responsible for defining information about the host
machine.  It includes @file{tm.h}.
@end ifset
@ifclear INTERNALS
A symbolic link named @file{config.h} is made to the top-level config
file for the machine you plan to run the compiler on (@pxref{Config,,The
Configuration File, gcc.info, Using and Porting GCC}).  This file is
responsible for defining information about the host machine.  It
includes @file{tm.h}.
@end ifclear

The top-level config file is located in the subdirectory @file{config}.
Its name is always @file{xm-@var{something}.h}; usually
@file{xm-@var{machine}.h}, but there are some exceptions.

If your system does not support symbolic links, you might want to
set up @file{config.h} to contain a @samp{#include} command which
refers to the appropriate file.

@item
A symbolic link named @file{tconfig.h} is made to the top-level config
file for your target machine.  This is used for compiling certain
programs to run on that machine.

@item
A symbolic link named @file{tm.h} is made to the machine-description
macro file for your target machine.  It should be in the subdirectory
@file{config} and its name is often @file{@var{machine}.h}.

@item
A symbolic link named @file{md} will be made to the machine description
pattern file.  It should be in the @file{config} subdirectory and its
name should be @file{@var{machine}.md}; but @var{machine} is often not
the same as the name used in the @file{tm.h} file because the
@file{md} files are more general.

@item
A symbolic link named @file{aux-output.c} will be made to the output
subroutine file for your machine.  It should be in the @file{config}
subdirectory and its name should be @file{@var{machine}.c}.

@item
The command file @file{configure} also constructs the file
@file{Makefile} by adding some text to the template file
@file{Makefile.in}.  The additional text comes from files in the
@file{config} directory, named @file{t-@var{target}} and
@file{x-@var{host}}.  If these files do not exist, it means nothing
needs to be added for a given target or host.
@c does the above work now?  --mew
@end itemize

@item
The standard directory for installing the compiler's passes and run-time
support in @file{/usr/local/lib}.  If you want to install it somewhere
else, specify the option @samp{--prefix=@var{dir}} when you run
@file{configure}.  @var{dir} is a directory name to use instead of
@file{/usr/local} for all purposes with one exception: the directory
@file{/usr/local/include} is searched for header files no matter where
you install the compiler.

@item
Specify @samp{--local-prefix=@var{dir}} if you want the compiler to
search directory @file{@var{dir}/include} for header files
@emph{instead} of @file{/usr/local/include}.  (This is for systems that
have different conventions for where to put site-specific things.)

@cindex Bison parser generator
@cindex parser generator, Bison
@item
Make sure the Bison parser generator is installed.  (This is
unnecessary if the Bison output files @file{c-parse.c} and
@file{cexp.c} are more recent than @file{c-parse.y} and @file{cexp.y}
and you do not plan to change the @samp{.y} files.)

Bison versions older than Sept 8, 1988 will produce incorrect output
for @file{c-parse.c}.

@item
Build the compiler.  Just type @samp{make LANGUAGES=c} in the compiler
directory.

@samp{LANGUAGES=c} specifies that only the C compiler should be
compiled.  The makefile normally builds compilers for all the supported
languages; currently, C, C++ and Objective C.  However, C is the only
language that is sure to work when you build with other non-GNU C
compilers.  In addition, building anything but C at this stage is a
waste of time.

In general, you can specify the languages to build by typing the
argument @samp{LANGUAGES="@var{list}"}, where @var{list} is one or more
words from the list @samp{c}, @samp{c++}, and @samp{objective-c}.

Ignore any warnings you may see about ``statement not reached'' in
@file{insn-emit.c}; they are normal.  Also, warnings about ``unknown
escape sequence'' are normal in @file{genopinit.c} and perhaps some
other files.  Any other compilation errors may represent bugs in the
port to your machine or operating system, and
@ifclear INSTALLONLY
should be investigated and reported (@pxref{Bugs}).
@end ifclear
@ifset INSTALLONLY
should be investigated and reported.
@end ifset

Some commercial compilers fail to compile GNU CC because they have bugs
or limitations.  For example, the Microsoft compiler is said to run out
of macro space.  Some Ultrix compilers run out of expression space; then
you need to break up the statement where the problem happens.

If you are building with a previous GNU C compiler, do not
use @samp{CC=gcc} on the make command or by editing the Makefile.
Instead, use a full pathname to specify the compiler, such as
@samp{CC=/usr/local/bin/gcc}.  This is because make might execute
the @file{gcc} in the current directory before all of the
compiler components have been built.

@item
If you are building a cross-compiler, stop here.  @xref{Cross-Compiler}.

@cindex stage1
@item
Move the first-stage object files and executables into a subdirectory
with this command:

@smallexample
make stage1
@end smallexample

The files are moved into a subdirectory named @file{stage1}.
Once installation is complete, you may wish to delete these files
with @code{rm -r stage1}.

@item
If you have chosen a configuration for GNU CC which requires other GNU
tools (such as GAS or the GNU linker) instead of the standard system
tools, install the required tools in the @file{stage1} subdirectory
under the names @file{as}, @file{ld} or whatever is appropriate.  This
will enable the stage 1 compiler to find the proper tools in the
following stage.

Alternatively, you can do subsequent compilation using a value of the
@code{PATH} environment variable such that the necessary GNU tools come
before the standard system tools.

@item
Recompile the compiler with itself, with this command:

@smallexample
make CC="stage1/xgcc -Bstage1/" CFLAGS="-g -O"
@end smallexample

This is called making the stage 2 compiler.

The command shown above builds compilers for all the supported
languages.  If you don't want them all, you can specify the languages to
build by typing the argument @samp{LANGUAGES="@var{list}"}.  @var{list}
should contain one or more words from the list @samp{c}, @samp{c++},
@samp{objective-c}, and @samp{proto}.  Separate the words with spaces.
@samp{proto} stands for the programs @code{protoize} and
@code{unprotoize}; they are not a separate language, but you use
@code{LANGUAGES} to enable or disable their installation.

If you are going to build the stage 3 compiler, then you might want to
build only the C language in stage 2.

Once you have built the stage 2 compiler, if you are short of disk
space, you can delete the subdirectory @file{stage1}.

On a 68000 or 68020 system lacking floating point hardware,
unless you have selected a @file{tm.h} file that expects by default
that there is no such hardware, do this instead:

@smallexample
make CC="stage1/xgcc -Bstage1/" CFLAGS="-g -O -msoft-float"
@end smallexample

@item
If you wish to test the compiler by compiling it with itself one more
time, install any other necessary GNU tools (such as GAS or the GNU
linker) in the @file{stage2} subdirectory as you did in the
@file{stage1} subdirectory, then do this:

@smallexample
make stage2
make CC="stage2/xgcc -Bstage2/" CFLAGS="-g -O" 
@end smallexample

@noindent
This is called making the stage 3 compiler.  Aside from the @samp{-B}
option, the compiler options should be the same as when you made the
stage 2 compiler.  But the @code{LANGUAGES} option need not be the
same.  The command shown above builds compilers for all the supported
languages; if you don't want them all, you can specify the languages to
build by typing the argument @samp{LANGUAGES="@var{list}"}, as described
above.

Then compare the latest object files with the stage 2 object
files---they ought to be identical, unless they contain time stamps.
You can compare the files, disregarding the time stamps if any, like
this:

@smallexample
make compare
@end smallexample

This will mention any object files that differ between stage 2 and stage
3.  Any difference, no matter how innocuous, indicates that the stage 2
compiler has compiled GNU CC incorrectly, and is therefore a potentially
@ifclear INSTALLONLY
serious bug which you should investigate and report (@pxref{Bugs}).
@end ifclear
@ifset INSTALLONLY
serious bug which you should investigate and report.
@end ifset

If your system does not put time stamps in the object files, then this
is a faster way to compare them (using the Bourne shell):

@smallexample
for file in *.o; do
cmp $file stage2/$file
done
@end smallexample

If you have built the compiler with the @samp{-mno-mips-tfile} option on
MIPS machines, you will not be able to compare the files.  The Alpha
uses timestamps that @samp{make compare} does not know how to ignore,
so you will not be able to compare on the Alpha.

@item
Install the compiler driver, the compiler's passes and run-time support
with @samp{make install}.  Use the same value for @code{CC},
@code{CFLAGS} and @code{LANGUAGES} that you used when compiling the
files that are being installed.  One reason this is necessary is that
some versions of Make have bugs and recompile files gratuitously when
you do this step.  If you use the same variable values, those files will
be recompiled properly.

For example, if you have built the stage 2 compiler, you can use the
following command:

@smallexample
make install CC="stage2/xgcc -Bstage2/" CFLAGS="-g -O" LANGUAGES="@var{list}"
@end smallexample

@noindent
This copies the files @file{cc1}, @file{cpp} and @file{libgcc.a} to
files @file{cc1}, @file{cpp} and @file{libgcc.a} in the directory
@file{/usr/local/lib/gcc-lib/@var{target}/@var{version}}, which is where
the compiler driver program looks for them.  Here @var{target} is the
target machine type specified when you ran @file{configure}, and
@var{version} is the version number of GNU CC.  This naming scheme
permits various versions and/or cross-compilers to coexist.

@c if the following doesn't work, i don't know what will; i've tried a
@c few ideas already.  --mew
This program will also copy the driver program @file{gcc} into the
directory @file{/usr/local/bin}, so that it appears in typical execution
search paths.@refill

On some systems, this command will cause recompilation of some files.
This is usually due to bugs in @code{make}.  You should either ignore
this problem, or use GNU Make.

@cindex @code{alloca} and SunOs
@strong{Warning: there is a bug in @code{alloca} in the Sun library.  To
avoid this bug, be sure to install the executables of GNU CC that were
compiled by GNU CC.  (That is, the executables from stage 2 or 3, not
stage 1.)  They use @code{alloca} as a built-in function and never the
one in the library.}

(It is usually better to install GNU CC executables from stage 2 or 3,
since they usually run faster than the ones compiled with some other
compiler.)

@item
Install the Objective C library (if you have built the Objective C
compiler).  Here is the command to do this:

@smallexample
make install-libobjc CC="stage2/xgcc -Bstage2/" CFLAGS="-g -O"
@end smallexample

@item
If you're going to use C++, it's likely that you need to also install
the libg++ distribution.  It should be available from the same
place where you got the GNU C distribution.  Just as GNU C does not
distribute a C runtime library, it also does not include a C++ run-time
library.  All I/O functionality, special class libraries, etc., are
available in the libg++ distribution.
@end enumerate

@node Other Dir
@section Compilation in a Separate Directory
@cindex other directory, compilation in
@cindex compilation in a separate directory
@cindex separate directory, compilation in

If you wish to build the object files and executables in a directory
other than the one containing the source files, here is what you must
do differently:

@enumerate
@item
Make sure you have a version of Make that supports the @code{VPATH}
feature.  (GNU Make supports it, as do Make versions on most BSD
systems.)

@item
If you have ever run @file{configure} in the source directory, you must undo
the configuration.  Do this by running:

@example
make distclean
@end example

@item
Go to the directory in which you want to build the compiler before
running @file{configure}:

@example
mkdir gcc-sun3
cd gcc-sun3
@end example

On systems that do not support symbolic links, this directory must be
on the same file system as the source code directory.

@item
Specify where to find @file{configure} when you run it:

@example
../gcc/configure @dots{}
@end example

This also tells @code{configure} where to find the compiler sources;
@code{configure} takes the directory from the file name that was used to
invoke it.  But if you want to be sure, you can specify the source
directory with the @samp{--srcdir} option, like this:

@example
../gcc/configure --srcdir=../gcc sun3
@end example

The directory you specify with @samp{--srcdir} need not be the same
as the one that @code{configure} is found in.
@end enumerate

Now, you can run @code{make} in that directory.  You need not repeat the
configuration steps shown above, when ordinary source files change.  You
must, however, run @code{configure} again when the configuration files
change, if your system does not support symbolic links.

@node Cross-Compiler
@section Building and Installing a Cross-Compiler
@cindex cross-compiler, installation

GNU CC can function as a cross-compiler for many machines, but not all.

@itemize @bullet
@item
Cross-compilers for the Mips as target do not work because the auxiliary
programs @file{mips-tdump.c} and @file{mips-tfile.c} can't be compiled
on anything but a Mips.

@item
Cross-compilers to or from the Vax probably don't work completely
because the Vax uses an incompatible floating point format (not IEEE
format).
@end itemize

Since GNU CC generates assembler code, you probably need a
cross-assembler that GNU CC can run, in order to produce object files.
If you want to link on other than the target machine, you need a
cross-linker as well.  You also need header files and libraries suitable
for the target machine that you can install on the host machine.

To build GNU CC as a cross-compiler, you start out by running
@code{configure}.  You must specify two different configurations, the
host and the target.  Use the @samp{--host=@var{host}} option for the
host and @samp{--target=@var{target}} to specify the target type.  For
example, here is how to configure for a cross-compiler that runs on a
hypothetical Intel 386 system and produces code for an HP 68030 system
running BSD:

@smallexample
configure --target=m68k-hp-bsd4.3 --host=i386-bozotheclone-bsd4.3
@end smallexample

Next you should install the cross-assembler and cross-linker (and
@code{ar} and @code{ranlib}).  Put them in the directory
@file{/usr/local/@var{target}/bin}.  The installation of GNU CC will find
them there and copy or link them to the proper place to find them when
you run the cross-compiler later.

If you want to install any additional libraries to use with the
cross-compiler, put them in the directory
@file{/usr/local/@var{target}/lib}; all files in that subdirectory will
be installed in the proper place when you install the cross-compiler.
Likewise, put the header files for the target machine in
@file{/usr/local/@var{target}/include}.

You must now produce a substitute for @file{libgcc1.a}.  Normally this
file is compiled with the ``native compiler'' for the target machine;
compiling it with GNU CC does not work.  But compiling it with the host
machine's compiler also doesn't work---that produces a file that would
run on the host, and you need it to run on the target.

We can't give you any automatic way to produce this substitute.  For
some targets, the subroutines in @file{libgcc1.c} are not actually used.
You need not provide the ones that won't be used.  The ones that most
commonly are used are the multiplication, division and remainder
routines---many RISC machines rely on the library for this.  One way to
make them work is to define the appropriate @code{perform_@dots{}}
macros for the subroutines that you need.  If these definitions do not
use the C arithmetic operators that they are meant to implement, you
might be able to compile them with the cross-compiler you are building.
To do this, specify @samp{LIBGCC1=libgcc1.a OLDCC=./xgcc} when building
the compiler.

Now you can proceed just as for compiling a single-machine compiler
through the step of building stage 1.  If you have not provided some
sort of @file{libgcc1.a}, then compilation will give up at the point
where it needs that file, printing a suitable error message.  If you
do provide @file{libgcc1.a}, then building the compiler will automatically
compile and link a test program called @file{cross-test}; if you get
errors in the linking, it means that not all of the necessary routines
in @file{libgcc1.a} are available.

When you are using a cross-compiler configuration, building stage 1
does not compile all of GNU CC.  This is because one part of building,
the compilation of @file{libgcc2.c}, requires use of the cross-compiler.

However, when you type @samp{make install} to install the bulk of the
cross-compiler, that will also compile @file{libgcc2.c} and install the
resulting @file{libgcc.a}.

Do not try to build stage 2 for a cross-compiler.  It doesn't work to
rebuild GNU CC as a cross-compiler using the cross-compiler, because
that would produce a program that runs on the target machine, not on the
host.  For example, if you compile a 386-to-68030 cross-compiler with
itself, the result will not be right either for the 386 (because it was
compiled into 68030 code) or for the 68030 (because it was configured
for a 386 as the host).  If you want to compile GNU CC into 68030 code,
whether you compile it on a 68030 or with a cross-compiler on a 386, you
must specify a 68030 as the host when you configure it.

@c this makes an underfull hbox; any ideas?  --mew 27jan93
@c Now fixed --bob 5feb93
@c Old text, page 83, was:
@c Installing GNU CC on the HP Precision Architecture
@node PA Install
@section GNU CC on the HP Precision Architecture

There are two variants of this CPU, called 1.0 and 1.1, which have
different machine descriptions.  You must use the right one for your
machine.  All 7@var{nn} machines and 8@var{n}7 machines use 1.1, while
all other 8@var{nn} machines use 1.0.

The easiest way to handle this problem is to use @samp{configure
hp@var{nnn}} or @samp{configure hp@var{nnn}-hpux}, where @var{nnn} is
the model number of the machine.  Then @file{configure} will figure out
if the machine is a 1.0 or 1.1.  Use @samp{uname -a} to find out the
model number of your machine.

@samp{-g} does not work on HP-UX, since that system uses a peculiar
debugging format which GNU CC does not know about.  There are preliminary
versions of GAS and GDB for the HP-PA which do work with GNU CC for 
debugging.  You can get them by anonymous ftp from @code{jaguar.cs.utah.edu}
@samp{dist} subdirectory.  You would need to install GAS in the file

@example
/usr/local/lib/gcc-lib/@var{configuration}/@var{gccversion}/as
@end example

@noindent
where @var{configuration} is the configuration name (perhaps
@samp{hp@var{nnn}-hpux}) and @var{gccversion} is the GNU CC version
number.  Do this @emph{before} starting the build process, otherwise you will
get errors from the HPUX assembler while building @file{libgcc2.a}.  The
command 

@example
make install-dir
@end example

@noindent
will create the necessary directory hierarchy so you can install GAS before
building GCC.

If you obtained GAS before October 6, 1992 it is highly recommended you
get a new one to avoid several bugs which have been discovered
recently.

To enable debugging, configure GNU CC with the @samp{--gas} option before
building.

It has been reported that GNU CC produces invalid assembly code for
1.1 machines running HP-UX 8.02 when using the HP assembler.  Typically
the errors look like this:
@example
as: bug.s @@line#15 [err#1060]
  Argument 0 or 2 in FARG upper
         - lookahead = ARGW1=FR,RTNVAL=GR
as: foo.s @@line#28 [err#1060]
  Argument 0 or 2 in FARG upper
         - lookahead = ARGW1=FR
@end example

You can check the version of HP-UX you are running by executing the command
@samp{uname -r}.   If you are indeed running HP-UX 8.02 on a 1.1 machine and 
using the HP assembler then configure GCC with "hp700-hpux8.02".

@node Sun Install
@section Installing GNU CC on the Sun
@cindex Sun installation
@cindex installing GNU CC on the Sun

Make sure the environment variable @code{FLOAT_OPTION} is not set when
you compile @file{libgcc.a}.  If this option were set to @code{f68881}
when @file{libgcc.a} is compiled, the resulting code would demand to be
linked with a special startup file and would not link properly without
special pains.

@cindex @code{alloca}, for SunOs
There is a bug in @code{alloca} in certain versions of the Sun library.
To avoid this bug, install the binaries of GNU CC that were compiled by
GNU CC.  They use @code{alloca} as a built-in function and never the one
in the library.

Some versions of the Sun compiler crash when compiling GNU CC.  The
problem is a segmentation fault in cpp.  This problem seems to be due to
the bulk of data in the environment variables.  You may be able to avoid
it by using the following command to compile GNU CC with Sun CC:

@example
make CC="TERMCAP=x OBJS=x LIBFUNCS=x STAGESTUFF=x cc"
@end example

@node 3b1 Install
@section Installing GNU CC on the 3b1
@cindex 3b1 installation
@cindex installing GNU CC on the 3b1

Installing GNU CC on the 3b1 is difficult if you do not already have
GNU CC running, due to bugs in the installed C compiler.  However,
the following procedure might work.  We are unable to test it.

@enumerate
@item
Comment out the @samp{#include "config.h"} line on line 37 of
@file{cccp.c} and do @samp{make cpp}.  This makes a preliminary version
of GNU cpp.

@item
Save the old @file{/lib/cpp} and copy the preliminary GNU cpp to that
file name.

@item
Undo your change in @file{cccp.c}, or reinstall the original version,
and do @samp{make cpp} again.

@item
Copy this final version of GNU cpp into @file{/lib/cpp}.

@findex obstack_free
@item
Replace every occurrence of @code{obstack_free} in the file
@file{tree.c} with @code{_obstack_free}.

@item
Run @code{make} to get the first-stage GNU CC.

@item
Reinstall the original version of @file{/lib/cpp}.

@item
Now you can compile GNU CC with itself and install it in the normal
fashion.
@end enumerate

@node Unos Install
@section Installing GNU CC on Unos
@cindex Unos installation
@cindex installing GNU CC on Unos

Use @samp{configure unos} for building on Unos.

The Unos assembler is named @code{casm} instead of @code{as}.  For some
strange reason linking @file{/bin/as} to @file{/bin/casm} changes the
behavior, and does not work.  So, when installing GNU CC, you should
install the following script as @file{as} in the subdirectory where
the passes of GCC are installed:

@example
#!/bin/sh
casm $*
@end example

The default Unos library is named @file{libunos.a} instead of
@file{libc.a}.  To allow GNU CC to function, either change all
references to @samp{-lc} in @file{gcc.c} to @samp{-lunos} or link
@file{/lib/libc.a} to @file{/lib/libunos.a}.

@cindex @code{alloca}, for Unos
When compiling GNU CC with the standard compiler, to overcome bugs in
the support of @code{alloca}, do not use @samp{-O} when making stage 2.
Then use the stage 2 compiler with @samp{-O} to make the stage 3
compiler.  This compiler will have the same characteristics as the usual
stage 2 compiler on other systems.  Use it to make a stage 4 compiler
and compare that with stage 3 to verify proper compilation.

(Perhaps simply defining @code{ALLOCA} in @file{x-crds} as described in
the comments there will make the above paragraph superfluous.  Please
inform us of whether this works.)

Unos uses memory segmentation instead of demand paging, so you will need
a lot of memory.  5 Mb is barely enough if no other tasks are running.
If linking @file{cc1} fails, try putting the object files into a library
and linking from that library.

@node VMS Install
@section Installing GNU CC on VMS
@cindex VMS installation
@cindex installing GNU CC on VMS

The VMS version of GNU CC is distributed in a backup saveset containing
both source code and precompiled binaries.

To install the @file{gcc} command so you can use the compiler easily, in
the same manner as you use the VMS C compiler, you must install the VMS CLD
file for GNU CC as follows:

@enumerate
@item
Define the VMS logical names @samp{GNU_CC} and @samp{GNU_CC_INCLUDE}
to point to the directories where the GNU CC executables
(@file{gcc-cpp.exe}, @file{gcc-cc1.exe}, etc.) and the C include files are
kept respectively.  This should be done with the commands:@refill

@smallexample
$ assign /system /translation=concealed -
  disk:[gcc.] gnu_cc
$ assign /system /translation=concealed -
  disk:[gcc.include.] gnu_cc_include
@end smallexample

@noindent
with the appropriate disk and directory names.  These commands can be
placed in your system startup file so they will be executed whenever
the machine is rebooted.  You may, if you choose, do this via the
@file{GCC_INSTALL.COM} script in the @file{[GCC]} directory.

@item
Install the @file{GCC} command with the command line:

@smallexample
$ set command /table=sys$common:[syslib]dcltables -
  /output=sys$common:[syslib]dcltables gnu_cc:[000000]gcc
$ install replace sys$common:[syslib]dcltables
@end smallexample

@item
To install the help file, do the following:

@smallexample
$ library/help sys$library:helplib.hlb gcc.hlp
@end smallexample

@noindent
Now you can invoke the compiler with a command like @samp{gcc /verbose
file.c}, which is equivalent to the command @samp{gcc -v -c file.c} in
Unix.
@end enumerate

If you wish to use GNU C++ you must first install GNU CC, and then
perform the following steps:

@enumerate
@item
Define the VMS logical name @samp{GNU_GXX_INCLUDE} to point to the
directory where the preprocessor will search for the C++ header files.
This can be done with the command:@refill

@smallexample
$ assign /system /translation=concealed -
  disk:[gcc.gxx_include.] gnu_gxx_include
@end smallexample

@noindent
with the appropriate disk and directory name.  If you are going to be
using libg++, this is where the libg++ install procedure will install
the libg++ header files.

@item
Obtain the file @file{gcc-cc1plus.exe}, and place this in the same
directory that @file{gcc-cc1.exe} is kept.

The GNU C++ compiler can be invoked with a command like @samp{gcc /plus
/verbose file.cc}, which is equivalent to the command @samp{g++ -v -c
file.cc} in Unix.
@end enumerate

We try to put corresponding binaries and sources on the VMS distribution
tape.  But sometimes the binaries will be from an older version than the
sources, because we don't always have time to update them.  (Use the
@samp{/version} option to determine the version number of the binaries and
compare it with the source file @file{version.c} to tell whether this is
so.)  In this case, you should use the binaries you get to recompile the
sources.  If you must recompile, here is how:

@enumerate
@item
Execute the command procedure @file{vmsconfig.com} to copy files
@file{vax-vms.h}, @file{xm-vax-vms.h}, @file{vax.c} and @file{vax.md} to
files @file{tm.h}, @file{config.h}, @file{aux-output.c}, and @file{md.}
respectively, and to create files @file{tconfig.h} and @file{hconfig.h}.
This procedure also creates several linker option files used by
@file{make-cc1.com} and a data file used by @file{make-l2.com}.@refill

@smallexample
$ @@vmsconfig.com
@end smallexample

@item
Setup the logical names and command tables as defined above.  In
addition, define the VMS logical name @samp{GNU_BISON} to point at the
to the directories where the Bison executable is kept.  This should be
done with the command:@refill

@smallexample
$ assign /system /translation=concealed -
  disk:[bison.] gnu_bison
@end smallexample

You may, if you choose, use the @file{INSTALL_BISON.COM} script in the
@file{[BISON]} directory.

@item
Install the @samp{BISON} command with the command line:@refill

@smallexample
$ set command /table=sys$common:[syslib]dcltables -
  /output=sys$common:[syslib]dcltables -
  gnu_bison:[000000]bison
$ install replace sys$common:[syslib]dcltables
@end smallexample

@item
Type @samp{@@make-gcc} to recompile everything (alternatively, you may
submit the file @file{make-gcc.com} to a batch queue).  If you wish to
build the GNU C++ compiler as well as the GNU CC compiler, you must
first edit @file{make-gcc.com} and follow the instructions that appear
in the comments.@refill

@item
In order to use GCC, you need a library of functions which GCC compiled code
will call to perform certain tasks, and these functions are defined in the
file @file{libgcc2.c}.  To compile this you should use the command procedure
@file{make-l2.com}, which will generate the library @file{libgcc2.olb}.
@file{libgcc2.olb} should be built using the compiler built from
the same distribution that @file{libgcc2.c} came from, and
@file{make-gcc.com} will automatically do all of this for you.

To install the library, use the following commands:@refill

@smallexample
$ library gnu_cc:[000000]gcclib/delete=(new,eprintf)
$ library gnu_cc:[000000]gcclib/delete=L_*
$ library libgcc2/extract=*/output=libgcc2.obj
$ library gnu_cc:[000000]gcclib libgcc2.obj
@end smallexample

The first command simply removes old modules that will be replaced with
modules from @file{libgcc2} under different module names.  The modules
@code{new} and @code{eprintf} may not actually be present in your
@file{gcclib.olb}---if the VMS librarian complains about those modules
not being present, simply ignore the message and continue on with the
next command.  The second command removes the modules that came from the
previous version of the library @file{libgcc2.c}.

Whenever you update the compiler on your system, you should also update the
library with the above procedure.

@item
You may wish to build GCC in such a way that no files are written to the
directory where the source files reside.  An example would be the when
the source files are on a read-only disk.  In these cases, execute the
following DCL commands (substituting your actual path names):

@smallexample
$ assign dua0:[gcc.build_dir.]/translation=concealed, -
         dua1:[gcc.source_dir.]/translation=concealed  gcc_build
$ set default gcc_build:[000000]
@end smallexample

where @file{dua1:[gcc.source_dir]}
contains the source code, and
@file{dua0:[gcc.build_dir]} is meant to contain all of the generated object
files and executables.  Once you have done this, you can proceed building GCC
as described above.  (Keep in mind that @file{gcc_build} is a rooted logical
name, and thus the device names in each element of the search list must be an
actual physical device name rather than another rooted logical name).

@item
@strong{If you are building GNU CC with a previous version of GNU CC,
you also should check to see that you have the newest version of the
assembler}.  In particular, GNU CC version 2 treats global constant
variables slightly differently from GNU CC version 1, and GAS version
1.38.1 does not have the patches required to work with GCC version 2.
If you use GAS 1.38.1, then @code{extern const} variables will not have
the read-only bit set, and the linker will generate warning messages
about mismatched psect attributes for these variables.  These warning
messages are merely a nuisance, and can safely be ignored.

If you are compiling with a version of GNU CC older than 1.33, specify
@samp{/DEFINE=("inline=")} as an option in all the compilations.  This
requires editing all the @code{gcc} commands in @file{make-cc1.com}.
(The older versions had problems supporting @code{inline}.)  Once you
have a working 1.33 or newer GNU CC, you can change this file back.

@item
If you want to build GNU CC with the VAX C compiler, you will need to
make minor changes in @file{make-cccp.com} and @file{make-cc1.com}
to choose alternate definitions of @code{CC}, @code{CFLAGS}, and
@code{LIBS}.  See comments in those files.  However, you must
also have a working version of the GNU assembler (GNU as, aka GAS) as
it is used as the back-end for GNU CC to produce binary object modules
and is not included in the GNU CC sources.  GAS is also needed to
compile @file{libgcc2} in order to build @file{gcclib} (see above);
@file{make-l2.com} expects to be able to find it operational in
@file{gnu_cc:[000000]gnu-as.exe}.

To use GNU CC on VMS, you need the VMS driver programs
@file{gcc.exe}, @file{gcc.com}, and @file{gcc.cld}.  They are
distributed with the VMS binaries (@file{gcc-vms}) rather than the
GNU CC sources.  GAS is also included in @file{gcc-vms}, as is Bison.

Once you have successfully built GNU CC with VAX C, you should use the
resulting compiler to rebuild itself.  Before doing this, be sure to
restore the @code{CC}, @code{CFLAGS}, and @code{LIBS} definitions in
@file{make-cccp.com} and @file{make-cc1.com}.  The second generation
compiler will be able to take advantage of many optimizations that must
be suppressed when building with other compilers.
@end enumerate

Under previous versions of GNU CC, the generated code would occasionally
give strange results when linked with the sharable @file{VAXCRTL} library.
Now this should work.

Even with this version, however, GNU CC itself should not be linked with
the sharable @file{VAXCRTL}.  The version of @code{qsort} in
@file{VAXCRTL} has a bug (known to be present in VMS versions V4.6
through V5.5) which causes the compiler to fail.

The executables are generated by @file{make-cc1.com} and
@file{make-cccp.com} use the object library version of @file{VAXCRTL} in
order to make use of the @code{qsort} routine in @file{gcclib.olb}.  If
you wish to link the compiler executables with the shareable image
version of @file{VAXCRTL}, you should edit the file @file{tm.h} (created
by @file{vmsconfig.com}) to define the macro @code{QSORT_WORKAROUND}.

@code{QSORT_WORKAROUND} is always defined when GNU CC is compiled with
VAX C, to avoid a problem in case @file{gcclib.olb} is not yet
available.


@node WE32K Install
@section Installing GNU CC on the WE32K

These computers are also known as the 3b2, 3b5, 3b20 and other similar
names.  (However, the 3b1 is actually a 68000; see @ref{3b1 Install}.)

Don't use @samp{-g} when compiling with the system's compiler.  The
system's linker seems to be unable to handle such a large program with
debugging information.

The system's compiler runs out of capacity when compiling @file{stmt.c}
in GNU CC.  You can work around this by building @file{cpp} in GNU CC
first, then use that instead of the system's preprocessor with the
system's C compiler to compile @file{stmt.c}.  Here is how:

@example
mv /lib/cpp /lib/cpp.att
cp cpp /lib/cpp.gnu
echo "/lib/cpp.gnu -traditional $*" > /lib/cpp
chmod +x /lib/cpp
@end example

The system's compiler produces bad code for some of the GNU CC
optimization files.  So you must build the stage 2 compiler without
optimization.  Then build a stage 3 compiler with optimization.
That executable should work.  Here are the necessary commands:

@example
make LANGUAGES=c CC=stage1/xgcc CFLAGS="-Bstage1/ -g"
make stage2
make CC=stage2/xgcc CFLAGS="-Bstage2/ -g -O"
@end example

You may need to raise the ULIMIT setting to build a C++ compiler,
as the file @file{cc1plus} is larger than one megabyte.


@node MIPS Install
@section Installing GNU CC on the MIPS

See @ref{Installation} about whether to use either of the options
@samp{--with-stabs} or @samp{--with-gnu-as}.

The MIPS C compiler needs to be told to increase its table size
for switch statements with the @samp{-Wf,-XNg1500} option in
order to compile @file{cp-parse.c}.  If you use the @samp{-O2}
optimization option, you also need to use @samp{-Olimit 3000}.
Both of these options are automatically generated in the
@file{Makefile} that the shell script @file{configure} builds.
If you override the @code{CC} make variable and use the MIPS
compilers, you may need to add @samp{-Wf,-XNg1500 -Olimit 3000}.

MIPS computers running RISC-OS can support four different
personalities: default, BSD 4.3, System V.3, and System V.4
(older versions of RISC-OS don't support V.4).  To configure GCC
for these platforms use the following configurations:

@table @samp
@item mips-mips-riscos@code{rev}
Default configuration for RISC-OS, revision @code{rev}.

@item mips-mips-riscos@code{rev}bsd
BSD 4.3 configuration for RISC-OS, revision @code{rev}.

@item mips-mips-riscos@code{rev}sysv4
System V.4 configuration for RISC-OS, revision @code{rev}.

@item mips-mips-riscos@code{rev}sysv
System V.3 configuration for RISC-OS, revision @code{rev}.
@end table

The revision @code{rev} mentioned above is the revision of
RISC-OS to use.  You must reconfigure GCC when going from a
RISC-OS revision 4 to RISC-OS revision 5.  This has the effect of
avoiding a linker
@ifclear INSTALLONLY
bug (see @ref{Installation Problems} for more details).
@end ifclear
@ifset INSTALLONLY
bug.
@end ifset

DECstations can support three different personalities: Ultrix,
DEC OSF/1, and OSF/rose.  To configure GCC for these platforms
use the following configurations:

@table @samp
@item decstation-ultrix
Ultrix configuration.

@item decstation-osf1
Dec's version of OSF/1.

@item decstation-osfrose
Open Software Foundation reference port of OSF/1 which uses the
OSF/rose object file format instead of ECOFF.  Normally, you
would not select this configuration.
@end table

On Irix version 4.0.5F, and perhaps on some other versions as well,
there is an assembler bug that reorders instructions incorrectly.  To
work around it, specify the target configuration
@samp{mips-sgi-irix4loser}.  This configuration inhibits assembler
optimization.

You can turn off assembler optimization in a compiler configured with
target @samp{mips-sgi-irix4} using the @samp{-noasmopt} option.  This
compiler option passes the option @samp{-O0} to the assembler, to
inhibit reordering.

The @samp{-noasmopt} option can be useful for testing whether a problem
is due to erroneous assembler reordering.  Even if a problem does not go
away with @samp{-noasmopt}, it may still be due to assembler
reordering---perhaps GNU CC itself was miscompiled as a result.

We know this is inconvenient, but it's the best that can be done at
the last minute.

@node Collect2
@section @code{collect2}

Many target systems do not have support in the assembler and linker for
``constructors''---initialization functions to be called before the
official ``start'' of @code{main}.  On such systems, GNU CC uses a
utility called @code{collect2} to arrange to call these functions at
start time.

The program @code{collect2} works by linking the program once and
looking through the linker output file for symbols with particular names
indicating they are constructor functions.  If it finds any, it
creates a new temporary @samp{.c} file containing a table of them,
compiles it, and links the program a second time including that file.

The actual calls to the constructors are carried out by a subroutine
called @code{__main}, which is called (automatically) at the beginning
of the body of @code{main} (provided @code{main} was compiled with GNU
CC).

The program @code{collect2} is installed as @code{ld} in the directory
where the passes of the compiler are installed.  When @code{collect2}
needs to find the @emph{real} @code{ld}, it tries the following file
names:

@itemize @bullet
@item
@file{gld} in the directories listed in the compiler's search
directories.

@item
@file{gld} in the directories listed in the environment variable
@code{PATH}.

@item
@file{real-ld} in the compiler's search directories.

@item
@file{real-ld} in @code{PATH}.

@item
@file{ld} in @code{PATH}.
@end itemize

``The compiler's search directories'' means all the directories where
@code{gcc} searches for passes of the compiler.  This includes
directories that you specify with @samp{-B}.

Cross compilers search a little differently:

@itemize @bullet
@item
@file{gld} in the compiler's search directories.

@item
@file{@var{target}-gld} in @code{PATH}.

@item
@file{real-ld} in the compiler's search directories.

@item
@file{@var{target}-real-ld} in @code{PATH}.

@item
@file{@var{target}-ld} in @code{PATH}.
@end itemize

@code{collect2} does not search for @file{ld} using the compiler's
search directories, because if it did, it would find itself---not the
real @code{ld}---and this could lead to infinite recursion.  However,
the directory where @code{collect2} is installed might happen to be in
@code{PATH}.  That could lead @code{collect2} to invoke itself anyway.
when looking for @code{ld}.

To prevent this, @code{collect2} explicitly avoids running @code{ld}
using the file name under which @code{collect2} itself was invoked.  In
fact, it remembers up to two such names---in case one copy of
@code{collect2} finds another copy (or version) of @code{collect2}
installed as @code{ld} in a second place in the search path.

If two file names to avoid are not sufficient, you may still encounter
an infinite recursion of @code{collect2} processes.  When this happens.
check all the files installed as @file{ld} in any of the directories
searched, and straighten out the situation.

(In a future version, we will probably change @code{collect2} to avoid
any reinvocation of a file from which any parent @code{collect2} was
run.)
