You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
386 lines
22 KiB
HTML
386 lines
22 KiB
HTML
<html lang="en">
|
|
<head>
|
|
<title>Installing GCC: Building</title>
|
|
<meta http-equiv="Content-Type" content="text/html">
|
|
<meta name="description" content="Installing GCC: Building">
|
|
<meta name="generator" content="makeinfo 4.13">
|
|
<link title="Top" rel="top" href="#Top">
|
|
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
|
|
<!--
|
|
Copyright (C) 1988-2015 Free Software Foundation, Inc.
|
|
|
|
Permission is granted to copy, distribute and/or modify this document
|
|
under the terms of the GNU Free Documentation License, Version 1.3 or
|
|
any later version published by the Free Software Foundation; with no
|
|
Invariant Sections, the Front-Cover texts being (a) (see below), and
|
|
with the Back-Cover Texts being (b) (see below). A copy of the
|
|
license is included in the section entitled "GNU Free Documentation License".
|
|
|
|
(a) The FSF's Front-Cover Text is:
|
|
|
|
A GNU Manual
|
|
|
|
(b) The FSF's Back-Cover Text is:
|
|
|
|
You have freedom to copy and modify this GNU Manual, like GNU
|
|
software. Copies published by the Free Software Foundation raise
|
|
funds for GNU development.-->
|
|
<meta http-equiv="Content-Style-Type" content="text/css">
|
|
<style type="text/css"><!--
|
|
pre.display { font-family:inherit }
|
|
pre.format { font-family:inherit }
|
|
pre.smalldisplay { font-family:inherit; font-size:smaller }
|
|
pre.smallformat { font-family:inherit; font-size:smaller }
|
|
pre.smallexample { font-size:smaller }
|
|
pre.smalllisp { font-size:smaller }
|
|
span.sc { font-variant:small-caps }
|
|
span.roman { font-family:serif; font-weight:normal; }
|
|
span.sansserif { font-family:sans-serif; font-weight:normal; }
|
|
--></style>
|
|
</head>
|
|
<body>
|
|
<h1 class="settitle">Installing GCC: Building</h1>
|
|
<a name="index-Installing-GCC_003a-Building-1"></a>
|
|
Now that GCC is configured, you are ready to build the compiler and
|
|
runtime libraries.
|
|
|
|
<p>Some commands executed when making the compiler may fail (return a
|
|
nonzero status) and be ignored by <samp><span class="command">make</span></samp>. These failures, which
|
|
are often due to files that were not found, are expected, and can safely
|
|
be ignored.
|
|
|
|
<p>It is normal to have compiler warnings when compiling certain files.
|
|
Unless you are a GCC developer, you can generally ignore these warnings
|
|
unless they cause compilation to fail. Developers should attempt to fix
|
|
any warnings encountered, however they can temporarily continue past
|
|
warnings-as-errors by specifying the configure flag
|
|
<samp><span class="option">--disable-werror</span></samp>.
|
|
|
|
<p>On certain old systems, defining certain environment variables such as
|
|
<samp><span class="env">CC</span></samp> can interfere with the functioning of <samp><span class="command">make</span></samp>.
|
|
|
|
<p>If you encounter seemingly strange errors when trying to build the
|
|
compiler in a directory other than the source directory, it could be
|
|
because you have previously configured the compiler in the source
|
|
directory. Make sure you have done all the necessary preparations.
|
|
|
|
<p>If you build GCC on a BSD system using a directory stored in an old System
|
|
V file system, problems may occur in running <samp><span class="command">fixincludes</span></samp> if the
|
|
System V file system doesn't support symbolic links. These problems
|
|
result in a failure to fix the declaration of <code>size_t</code> in
|
|
<samp><span class="file">sys/types.h</span></samp>. If you find that <code>size_t</code> is a signed type and
|
|
that type mismatches occur, this could be the cause.
|
|
|
|
<p>The solution is not to use such a directory for building GCC.
|
|
|
|
<p>Similarly, when building from SVN or snapshots, or if you modify
|
|
<samp><span class="file">*.l</span></samp> files, you need the Flex lexical analyzer generator
|
|
installed. If you do not modify <samp><span class="file">*.l</span></samp> files, releases contain
|
|
the Flex-generated files and you do not need Flex installed to build
|
|
them. There is still one Flex-based lexical analyzer (part of the
|
|
build machinery, not of GCC itself) that is used even if you only
|
|
build the C front end.
|
|
|
|
<p>When building from SVN or snapshots, or if you modify Texinfo
|
|
documentation, you need version 4.7 or later of Texinfo installed if you
|
|
want Info documentation to be regenerated. Releases contain Info
|
|
documentation pre-built for the unmodified documentation in the release.
|
|
|
|
<h3 class="section"><a name="TOC0"></a>Building a native compiler</h3>
|
|
|
|
<p>For a native build, the default configuration is to perform
|
|
a 3-stage bootstrap of the compiler when ‘<samp><span class="samp">make</span></samp>’ is invoked.
|
|
This will build the entire GCC system and ensure that it compiles
|
|
itself correctly. It can be disabled with the <samp><span class="option">--disable-bootstrap</span></samp>
|
|
parameter to ‘<samp><span class="samp">configure</span></samp>’, but bootstrapping is suggested because
|
|
the compiler will be tested more completely and could also have
|
|
better performance.
|
|
|
|
<p>The bootstrapping process will complete the following steps:
|
|
|
|
<ul>
|
|
<li>Build tools necessary to build the compiler.
|
|
|
|
<li>Perform a 3-stage bootstrap of the compiler. This includes building
|
|
three times the target tools for use by the compiler such as binutils
|
|
(bfd, binutils, gas, gprof, ld, and opcodes) if they have been
|
|
individually linked or moved into the top level GCC source tree before
|
|
configuring.
|
|
|
|
<li>Perform a comparison test of the stage2 and stage3 compilers.
|
|
|
|
<li>Build runtime libraries using the stage3 compiler from the previous step.
|
|
|
|
</ul>
|
|
|
|
<p>If you are short on disk space you might consider ‘<samp><span class="samp">make
|
|
bootstrap-lean</span></samp>’ instead. The sequence of compilation is the
|
|
same described above, but object files from the stage1 and
|
|
stage2 of the 3-stage bootstrap of the compiler are deleted as
|
|
soon as they are no longer needed.
|
|
|
|
<p>If you wish to use non-default GCC flags when compiling the stage2
|
|
and stage3 compilers, set <code>BOOT_CFLAGS</code> on the command line when
|
|
doing ‘<samp><span class="samp">make</span></samp>’. For example, if you want to save additional space
|
|
during the bootstrap and in the final installation as well, you can
|
|
build the compiler binaries without debugging information as in the
|
|
following example. This will save roughly 40% of disk space both for
|
|
the bootstrap and the final installation. (Libraries will still contain
|
|
debugging information.)
|
|
|
|
<pre class="smallexample"> make BOOT_CFLAGS='-O' bootstrap
|
|
</pre>
|
|
<p>You can place non-default optimization flags into <code>BOOT_CFLAGS</code>; they
|
|
are less well tested here than the default of ‘<samp><span class="samp">-g -O2</span></samp>’, but should
|
|
still work. In a few cases, you may find that you need to specify special
|
|
flags such as <samp><span class="option">-msoft-float</span></samp> here to complete the bootstrap; or,
|
|
if the native compiler miscompiles the stage1 compiler, you may need
|
|
to work around this, by choosing <code>BOOT_CFLAGS</code> to avoid the parts
|
|
of the stage1 compiler that were miscompiled, or by using ‘<samp><span class="samp">make
|
|
bootstrap4</span></samp>’ to increase the number of stages of bootstrap.
|
|
|
|
<p><code>BOOT_CFLAGS</code> does not apply to bootstrapped target libraries.
|
|
Since these are always compiled with the compiler currently being
|
|
bootstrapped, you can use <code>CFLAGS_FOR_TARGET</code> to modify their
|
|
compilation flags, as for non-bootstrapped target libraries.
|
|
Again, if the native compiler miscompiles the stage1 compiler, you may
|
|
need to work around this by avoiding non-working parts of the stage1
|
|
compiler. Use <code>STAGE1_TFLAGS</code> to this end.
|
|
|
|
<p>If you used the flag <samp><span class="option">--enable-languages=...</span></samp> to restrict
|
|
the compilers to be built, only those you've actually enabled will be
|
|
built. This will of course only build those runtime libraries, for
|
|
which the particular compiler has been built. Please note,
|
|
that re-defining <samp><span class="env">LANGUAGES</span></samp> when calling ‘<samp><span class="samp">make</span></samp>’
|
|
<strong>does not</strong> work anymore!
|
|
|
|
<p>If the comparison of stage2 and stage3 fails, this normally indicates
|
|
that the stage2 compiler has compiled GCC incorrectly, and is therefore
|
|
a potentially serious bug which you should investigate and report. (On
|
|
a few systems, meaningful comparison of object files is impossible; they
|
|
always appear “different”. If you encounter this problem, you will
|
|
need to disable comparison in the <samp><span class="file">Makefile</span></samp>.)
|
|
|
|
<p>If you do not want to bootstrap your compiler, you can configure with
|
|
<samp><span class="option">--disable-bootstrap</span></samp>. In particular cases, you may want to
|
|
bootstrap your compiler even if the target system is not the same as
|
|
the one you are building on: for example, you could build a
|
|
<code>powerpc-unknown-linux-gnu</code> toolchain on a
|
|
<code>powerpc64-unknown-linux-gnu</code> host. In this case, pass
|
|
<samp><span class="option">--enable-bootstrap</span></samp> to the configure script.
|
|
|
|
<p><code>BUILD_CONFIG</code> can be used to bring in additional customization
|
|
to the build. It can be set to a whitespace-separated list of names.
|
|
For each such <code>NAME</code>, top-level <samp><span class="file">config/</span><code>NAME</code><span class="file">.mk</span></samp> will
|
|
be included by the top-level <samp><span class="file">Makefile</span></samp>, bringing in any settings
|
|
it contains. The default <code>BUILD_CONFIG</code> can be set using the
|
|
configure option <samp><span class="option">--with-build-config=</span><code>NAME</code><span class="option">...</span></samp>. Some
|
|
examples of supported build configurations are:
|
|
|
|
<dl>
|
|
<dt>‘<samp><span class="samp">bootstrap-O1</span></samp>’<dd>Removes any <samp><span class="option">-O</span></samp>-started option from <code>BOOT_CFLAGS</code>, and adds
|
|
<samp><span class="option">-O1</span></samp> to it. ‘<samp><span class="samp">BUILD_CONFIG=bootstrap-O1</span></samp>’ is equivalent to
|
|
‘<samp><span class="samp">BOOT_CFLAGS='-g -O1'</span></samp>’.
|
|
|
|
<br><dt>‘<samp><span class="samp">bootstrap-O3</span></samp>’<dd>Analogous to <code>bootstrap-O1</code>.
|
|
|
|
<br><dt>‘<samp><span class="samp">bootstrap-lto</span></samp>’<dd>Enables Link-Time Optimization for host tools during bootstrapping.
|
|
‘<samp><span class="samp">BUILD_CONFIG=bootstrap-lto</span></samp>’ is equivalent to adding
|
|
<samp><span class="option">-flto</span></samp> to ‘<samp><span class="samp">BOOT_CFLAGS</span></samp>’. This option assumes that the host
|
|
supports the linker plugin (e.g. GNU ld version 2.21 or later or GNU gold
|
|
version 2.21 or later).
|
|
|
|
<br><dt>‘<samp><span class="samp">bootstrap-lto-noplugin</span></samp>’<dd>This option is similar to <code>bootstrap-lto</code>, but is intended for
|
|
hosts that do not support the linker plugin. Without the linker plugin
|
|
static libraries are not compiled with link-time optimizations. Since
|
|
the GCC middle end and back end are in <samp><span class="file">libbackend.a</span></samp> this means
|
|
that only the front end is actually LTO optimized.
|
|
|
|
<br><dt>‘<samp><span class="samp">bootstrap-debug</span></samp>’<dd>Verifies that the compiler generates the same executable code, whether
|
|
or not it is asked to emit debug information. To this end, this
|
|
option builds stage2 host programs without debug information, and uses
|
|
<samp><span class="file">contrib/compare-debug</span></samp> to compare them with the stripped stage3
|
|
object files. If <code>BOOT_CFLAGS</code> is overridden so as to not enable
|
|
debug information, stage2 will have it, and stage3 won't. This option
|
|
is enabled by default when GCC bootstrapping is enabled, if
|
|
<code>strip</code> can turn object files compiled with and without debug
|
|
info into identical object files. In addition to better test
|
|
coverage, this option makes default bootstraps faster and leaner.
|
|
|
|
<br><dt>‘<samp><span class="samp">bootstrap-debug-big</span></samp>’<dd>Rather than comparing stripped object files, as in
|
|
<code>bootstrap-debug</code>, this option saves internal compiler dumps
|
|
during stage2 and stage3 and compares them as well, which helps catch
|
|
additional potential problems, but at a great cost in terms of disk
|
|
space. It can be specified in addition to ‘<samp><span class="samp">bootstrap-debug</span></samp>’.
|
|
|
|
<br><dt>‘<samp><span class="samp">bootstrap-debug-lean</span></samp>’<dd>This option saves disk space compared with <code>bootstrap-debug-big</code>,
|
|
but at the expense of some recompilation. Instead of saving the dumps
|
|
of stage2 and stage3 until the final compare, it uses
|
|
<samp><span class="option">-fcompare-debug</span></samp> to generate, compare and remove the dumps
|
|
during stage3, repeating the compilation that already took place in
|
|
stage2, whose dumps were not saved.
|
|
|
|
<br><dt>‘<samp><span class="samp">bootstrap-debug-lib</span></samp>’<dd>This option tests executable code invariance over debug information
|
|
generation on target libraries, just like <code>bootstrap-debug-lean</code>
|
|
tests it on host programs. It builds stage3 libraries with
|
|
<samp><span class="option">-fcompare-debug</span></samp>, and it can be used along with any of the
|
|
<code>bootstrap-debug</code> options above.
|
|
|
|
<p>There aren't <code>-lean</code> or <code>-big</code> counterparts to this option
|
|
because most libraries are only build in stage3, so bootstrap compares
|
|
would not get significant coverage. Moreover, the few libraries built
|
|
in stage2 are used in stage3 host programs, so we wouldn't want to
|
|
compile stage2 libraries with different options for comparison purposes.
|
|
|
|
<br><dt>‘<samp><span class="samp">bootstrap-debug-ckovw</span></samp>’<dd>Arranges for error messages to be issued if the compiler built on any
|
|
stage is run without the option <samp><span class="option">-fcompare-debug</span></samp>. This is
|
|
useful to verify the full <samp><span class="option">-fcompare-debug</span></samp> testing coverage. It
|
|
must be used along with <code>bootstrap-debug-lean</code> and
|
|
<code>bootstrap-debug-lib</code>.
|
|
|
|
<br><dt>‘<samp><span class="samp">bootstrap-time</span></samp>’<dd>Arranges for the run time of each program started by the GCC driver,
|
|
built in any stage, to be logged to <samp><span class="file">time.log</span></samp>, in the top level of
|
|
the build tree.
|
|
|
|
</dl>
|
|
|
|
<h3 class="section"><a name="TOC1"></a>Building a cross compiler</h3>
|
|
|
|
<p>When building a cross compiler, it is not generally possible to do a
|
|
3-stage bootstrap of the compiler. This makes for an interesting problem
|
|
as parts of GCC can only be built with GCC.
|
|
|
|
<p>To build a cross compiler, we recommend first building and installing a
|
|
native compiler. You can then use the native GCC compiler to build the
|
|
cross compiler. The installed native compiler needs to be GCC version
|
|
2.95 or later.
|
|
|
|
<p>If the cross compiler is to be built with support for the Java
|
|
programming language and the ability to compile .java source files is
|
|
desired, the installed native compiler used to build the cross
|
|
compiler needs to be the same GCC version as the cross compiler. In
|
|
addition the cross compiler needs to be configured with
|
|
<samp><span class="option">--with-ecj-jar=...</span></samp>.
|
|
|
|
<p>Assuming you have already installed a native copy of GCC and configured
|
|
your cross compiler, issue the command <samp><span class="command">make</span></samp>, which performs the
|
|
following steps:
|
|
|
|
<ul>
|
|
<li>Build host tools necessary to build the compiler.
|
|
|
|
<li>Build target tools for use by the compiler such as binutils (bfd,
|
|
binutils, gas, gprof, ld, and opcodes)
|
|
if they have been individually linked or moved into the top level GCC source
|
|
tree before configuring.
|
|
|
|
<li>Build the compiler (single stage only).
|
|
|
|
<li>Build runtime libraries using the compiler from the previous step.
|
|
</ul>
|
|
|
|
<p>Note that if an error occurs in any step the make process will exit.
|
|
|
|
<p>If you are not building GNU binutils in the same source tree as GCC,
|
|
you will need a cross-assembler and cross-linker installed before
|
|
configuring GCC. Put them in the directory
|
|
<samp><var>prefix</var><span class="file">/</span><var>target</var><span class="file">/bin</span></samp>. Here is a table of the tools
|
|
you should put in this directory:
|
|
|
|
<dl>
|
|
<dt><samp><span class="file">as</span></samp><dd>This should be the cross-assembler.
|
|
|
|
<br><dt><samp><span class="file">ld</span></samp><dd>This should be the cross-linker.
|
|
|
|
<br><dt><samp><span class="file">ar</span></samp><dd>This should be the cross-archiver: a program which can manipulate
|
|
archive files (linker libraries) in the target machine's format.
|
|
|
|
<br><dt><samp><span class="file">ranlib</span></samp><dd>This should be a program to construct a symbol table in an archive file.
|
|
</dl>
|
|
|
|
<p>The installation of GCC 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.
|
|
|
|
<p>The easiest way to provide these files is to build the Binutils package.
|
|
Configure it with the same <samp><span class="option">--host</span></samp> and <samp><span class="option">--target</span></samp>
|
|
options that you use for configuring GCC, then build and install
|
|
them. They install their executables automatically into the proper
|
|
directory. Alas, they do not support all the targets that GCC
|
|
supports.
|
|
|
|
<p>If you are not building a C library in the same source tree as GCC,
|
|
you should also provide the target libraries and headers before
|
|
configuring GCC, specifying the directories with
|
|
<samp><span class="option">--with-sysroot</span></samp> or <samp><span class="option">--with-headers</span></samp> and
|
|
<samp><span class="option">--with-libs</span></samp>. Many targets also require “start files” such
|
|
as <samp><span class="file">crt0.o</span></samp> and
|
|
<samp><span class="file">crtn.o</span></samp> which are linked into each executable. There may be several
|
|
alternatives for <samp><span class="file">crt0.o</span></samp>, for use with profiling or other
|
|
compilation options. Check your target's definition of
|
|
<code>STARTFILE_SPEC</code> to find out what start files it uses.
|
|
|
|
<h3 class="section"><a name="TOC2"></a>Building in parallel</h3>
|
|
|
|
<p>GNU Make 3.80 and above, which is necessary to build GCC, support
|
|
building in parallel. To activate this, you can use ‘<samp><span class="samp">make -j 2</span></samp>’
|
|
instead of ‘<samp><span class="samp">make</span></samp>’. You can also specify a bigger number, and
|
|
in most cases using a value greater than the number of processors in
|
|
your machine will result in fewer and shorter I/O latency hits, thus
|
|
improving overall throughput; this is especially true for slow drives
|
|
and network filesystems.
|
|
|
|
<h3 class="section"><a name="TOC3"></a>Building the Ada compiler</h3>
|
|
|
|
<p>In order to build GNAT, the Ada compiler, you need a working GNAT
|
|
compiler (GCC version 4.0 or later).
|
|
This includes GNAT tools such as <samp><span class="command">gnatmake</span></samp> and
|
|
<samp><span class="command">gnatlink</span></samp>, since the Ada front end is written in Ada and
|
|
uses some GNAT-specific extensions.
|
|
|
|
<p>In order to build a cross compiler, it is suggested to install
|
|
the new compiler as native first, and then use it to build the cross
|
|
compiler.
|
|
|
|
<p><samp><span class="command">configure</span></samp> does not test whether the GNAT installation works
|
|
and has a sufficiently recent version; if too old a GNAT version is
|
|
installed, the build will fail unless <samp><span class="option">--enable-languages</span></samp> is
|
|
used to disable building the Ada front end.
|
|
|
|
<p><samp><span class="env">ADA_INCLUDE_PATH</span></samp> and <samp><span class="env">ADA_OBJECT_PATH</span></samp> environment variables
|
|
must not be set when building the Ada compiler, the Ada tools, or the
|
|
Ada runtime libraries. You can check that your build environment is clean
|
|
by verifying that ‘<samp><span class="samp">gnatls -v</span></samp>’ lists only one explicit path in each
|
|
section.
|
|
|
|
<h3 class="section"><a name="TOC4"></a>Building with profile feedback</h3>
|
|
|
|
<p>It is possible to use profile feedback to optimize the compiler itself. This
|
|
should result in a faster compiler binary. Experiments done on x86 using gcc
|
|
3.3 showed approximately 7 percent speedup on compiling C programs. To
|
|
bootstrap the compiler with profile feedback, use <code>make profiledbootstrap</code>.
|
|
|
|
<p>When ‘<samp><span class="samp">make profiledbootstrap</span></samp>’ is run, it will first build a <code>stage1</code>
|
|
compiler. This compiler is used to build a <code>stageprofile</code> compiler
|
|
instrumented to collect execution counts of instruction and branch
|
|
probabilities. Then runtime libraries are compiled with profile collected.
|
|
Finally a <code>stagefeedback</code> compiler is built using the information collected.
|
|
|
|
<p>Unlike standard bootstrap, several additional restrictions apply. The
|
|
compiler used to build <code>stage1</code> needs to support a 64-bit integral type.
|
|
It is recommended to only use GCC for this.
|
|
|
|
<p><hr />
|
|
<p><a href="./index.html">Return to the GCC Installation page</a>
|
|
|
|
<!-- ***Testing***************************************************************** -->
|
|
<!-- ***Final install*********************************************************** -->
|
|
<!-- ***Binaries**************************************************************** -->
|
|
<!-- ***Specific**************************************************************** -->
|
|
<!-- ***Old documentation****************************************************** -->
|
|
<!-- ***GFDL******************************************************************** -->
|
|
<!-- *************************************************************************** -->
|
|
<!-- Part 6 The End of the Document -->
|
|
</body></html>
|
|
|