install.texi

gcc库的原代码,对编程有很大帮助.

Embedded PowerPC system in big endian mode for use in running under the
PSIM simulator.  This system is currently under development.

@item powerpc-*-eabi
Embedded PowerPC system in big endian mode.

This configuration is currently under development.

@item powerpcle-*-elf
@itemx powerpcle-*-sysv4
PowerPC system in little endian mode, running System V.4.

This configuration is currently under development.

@itemx powerpcle-*-sysv4
Embedded PowerPC system in little endian mode.

This system is currently under development.

@item powerpcle-*-eabisim
Embedded PowerPC system in little endian mode for use in running under
the PSIM simulator.

This system is currently under development.

@itemx powerpcle-*-eabi
Embedded PowerPC system in little endian mode.

This configuration is currently under development.

@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.

@item sparc-sun-*
See @ref{Sun Install}, for information on installing GNU CC on Sun
systems.

@item vax-dec-vms
See @ref{VMS Install}, for details on how to install GNU CC on VMS.

@item we32k-*-*
These computers are also known as the 3b2, 3b5, 3b20 and other similar
names.  (However, the 3b1 is actually a 68000; see
@ref{Configurations}.)

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 $@{1+"$@@"@}' > /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.
@end table

@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 @var{other options}
@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 using the Mips assembler
currently 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.  It does work to cross compile for a Mips
if you use the GNU assembler and linker.

@item
Cross-compilers between machines with different floating point formats
have not all been made to work.  GNU CC now has a floating point
emulator with which these can work, but each target machine description
needs to be updated to take advantage of it.

@item 
Cross-compilation between machines of different word sizes is
somewhat problematic and sometimes does not work.
@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.

@menu
* Steps of Cross::      Using a cross-compiler involves several steps
                          that may be carried out on different machines.
* Configure Cross::     Configuring a cross-compiler.
* Tools and Libraries:: Where to put the linker and assembler, and the C library.
* Cross Headers::       Finding and installing header files
                          for a cross-compiler.
* Cross Runtime::       Supplying arithmetic runtime routines (@file{libgcc1.a}).
* Build Cross::         Actually compiling the cross-compiler.
@end menu

@node Steps of Cross
@subsection Steps of Cross-Compilation

To compile and run a program using a cross-compiler involves several
steps:

@itemize @bullet
@item
Run the cross-compiler on the host machine to produce assembler files
for the target machine.  This requires header files for the target
machine.

@item
Assemble the files produced by the cross-compiler.  You can do this
either with an assembler on the target machine, or with a
cross-assembler on the host machine.

@item
Link those files to make an executable.  You can do this either with a
linker on the target machine, or with a cross-linker on the host
machine.  Whichever machine you use, you need libraries and certain
startup files (typically @file{crt@dots{}.o}) for the target machine.
@end itemize

It is most convenient to do all of these steps on the same host machine,
since then you can do it all with a single invocation of GNU CC.  This
requires a suitable cross-assembler and cross-linker.  For some targets,
the GNU assembler and linker are available.

@node Configure Cross
@subsection Configuring a Cross-Compiler

To build GNU CC as a cross-compiler, you start out by running
@file{configure}.  Use the @samp{--target=@var{target}} to specify the
target type.  If @file{configure} was unable to correctly identify the
system you are running on, also specify the @samp{--build=@var{build}}
option.  For example, here is how to configure for a cross-compiler that
produces code for an HP 68030 system running BSD on a system that
@file{configure} can correctly identify:

@smallexample
./configure --target=m68k-hp-bsd4.3
@end smallexample

@node Tools and Libraries
@subsection Tools and Libraries for a Cross-Compiler

If you have a cross-assembler and cross-linker available, you should
install them now.  Put them in the directory
@file{/usr/local/@var{target}/bin}.  Here is a table of the tools
you should put in this directory:

@table @file
@item as
This should be the cross-assembler.

@item ld
This should be the cross-linker.

@item ar
This should be the cross-archiver: a program which can manipulate
archive files (linker libraries) in the target machine's format.

@item ranlib
This should be a program to construct a symbol table in an archive file.
@end table

The installation of GNU CC will find these programs in that directory,
and copy or link them to the proper place to for the cross-compiler to
find them when run later.

The easiest way to provide these files is to build the Binutils package
and GAS.  Configure them with the same @samp{--host} and @samp{--target}
options that you use for configuring GNU CC, then build and install
them.  They install their executables automatically into the proper
directory.  Alas, they do not support all the targets that GNU CC
supports.

If you want to install libraries to use with the cross-compiler, such as
a standard C library, put them in the directory
@file{/usr/local/@var{target}/lib}; installation of GNU CC copies all
all the files in that subdirectory into the proper place for GNU CC to
find them and link with them.  Here's an example of copying some
libraries from a target machine:

@example
ftp @var{target-machine}
lcd /usr/local/@var{target}/lib
cd /lib
get libc.a
cd /usr/lib
get libg.a
get libm.a
quit
@end example

@noindent
The precise set of libraries you'll need, and their locations on
the target machine, vary depending on its operating system.

@cindex start files
Many targets require ``start files'' such as @file{crt0.o} and
@file{crtn.o} which are linked into each executable; these too should be
placed in @file{/usr/local/@var{target}/lib}.  There may be several
alternatives for @file{crt0.o}, for use with profiling or other
compilation options.  Check your target's definition of
@code{STARTFILE_SPEC} to find out what start files it uses.
Here's an example of copying these files from a target machine:

@example
ftp @var{target-machine}
lcd /usr/local/@var{target}/lib
prompt
cd /lib
mget *crt*.o
cd /usr/lib
mget *crt*.o
quit
@end example

@node Cross Runtime
@subsection @file{libgcc.a} and Cross-Compilers

Code compiled by GNU CC uses certain runtime support functions
implicitly.  Some of these functions can be compiled successfully with
GNU CC itself, but a few cannot be.  These problem functions are in the
source file @file{libgcc1.c}; the library made from them is called
@file{libgcc1.a}.

When you build a native compiler, these functions are compiled with some
other compiler--the one that you use for bootstrapping GNU CC.
Presumably it knows how to open code these operations, or else knows how
to call the run-time emulation facilities that the machine comes with.
But this approach doesn't work for building a cross-compiler.  The
compiler that you use for building knows about the host system, not the
target system.

So, when you build a