install.texi

gcc库的原代码,对编程有很大帮助.

@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 -O2"
@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 -O2 -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 -O2" 
@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.

If you do not have to install any additional GNU tools, you may use the
command

@smallexample
make bootstrap LANGUAGES=@var{language-list} BOOT_CFLAGS=@var{option-list}
@end smallexample

@noindent
instead of making @file{stage1}, @file{stage2}, and performing
the two compiler builds.

@item
Then compare the latest object files with the stage 2 object
files---they ought to be identical, aside from time stamps (if any).

On some systems, meaningful comparison of object files is impossible;
they always appear ``different.''  This is currently true on Solaris and
some systems that use ELF object file format.  On some versions of Irix
on SGI machines and DEC Unix (OSF/1) on Alpha systems, you will not be
able to compare the files without specifying @file{-save-temps}; see the
description of individual systems above to see if you get comparison
failures.  You may have similar problems on other systems.

Use this command to compare the files:

@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.

@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.

This also copies the driver program @file{xgcc} into
@file{/usr/local/bin/gcc}, so that it appears in typical execution
search paths.

On some systems, this command causes 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
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 Configurations
@section Configurations Supported by GNU CC
@cindex configurations supported by GNU CC

Here are the possible CPU types:

@quotation
@c gmicro, alliant, spur and tahoe omitted since they don't work.
1750a, a29k, alpha, arm, c@var{n}, clipper, dsp16xx, elxsi, h8300,
hppa1.0, hppa1.1, i370, i386, i486, i586, i860, i960, m68000, m68k,
m88k, mips, mipsel, mips64, mips64el, ns32k, powerpc, powerpcle,
pyramid, romp, rs6000, sh, sparc, sparclite, sparc64, 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
acorn, 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, wrs.
@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
386bsd, aix, acis, amigados, aos, aout, bosx, bsd, clix, coff, ctix, cxux,
dgux, dynix, ebmon, ecoff, elf, esix, freebsd, hms, genix, gnu, gnu/linux,
hiux, hpux, iris, irix, isc, luna, lynxos, mach, minix, msdos, mvs,
netbsd, newsos, nindy, ns, osf, osfrose, ptx, riscix, riscos, rtu, sco, sim,
solaris, sunos, sym, sysv, udi, ultrix, unicos, uniplus, unos, vms, vsta,
vxworks, winnt, xenix.
@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.  GNU CC does not support all possible alternatives.

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, powerpc, powerpcle, 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.
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}, configuration uses
files @file{m68k.md}, @file{local.h}, @file{m68k.c},
@file{xm-local.h}, @file{t-local}, and @file{x-local}, all in the
directory @file{config/m68k}.

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

@table @samp
@item 1750a-*-*
MIL-STD-1750A processors.

Starting with GCC 2.6.1, the MIL-STD-1750A cross configuration no longer
supports the Tektronix Assembler, but instead produces output for
@code{as1750}, an assembler/linker available under the GNU Public
License for the 1750A. Contact @emph{kellogg@@space.otn.dasa.de} for more
details on obtaining @samp{as1750}.  A similarly licensed simulator for
the 1750A is available from same address.

You should ignore a fatal error during the building of libgcc (libgcc is
not yet implemented for the 1750A.)

The @code{as1750} assembler requires the file @file{ms1750.inc}, which is
found in the directory @file{config/1750a}.

GNU CC produced the same sections as the Fairchild F9450 C Compiler,
namely:

@table @code
@item Normal
The program code section.

@item Static
The read/write (RAM) data section.

@item Konst
The read-only (ROM) constants section.

@item Init
Initialization section (code to copy KREL to SREL).
@end table

The smallest addressable unit is 16 bits (BITS_PER_UNIT is 16).  This
means that type `char' is represented with a 16-bit word per character.
The 1750A's "Load/Store Upper/Lower Byte" instructions are not used by
GNU CC.

@item alpha-*-osf1
Systems using processors that implement the DEC Alpha architecture and
are running the DEC Unix (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 system header file @file{/usr/include/stamp.h}.  If you install a
new version of DEC Unix, 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 code as efficient 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