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diff --git a/INSTALL/build.html b/INSTALL/build.html index 69d07bb280..c2f44ab1c7 100644 --- a/INSTALL/build.html +++ b/INSTALL/build.html @@ -1,385 +1,471 @@ -<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 4.12"> -<link title="Top" rel="top" href="#Top"> -<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> -<!-- -Copyright (C) 1988-2016 Free Software Foundation, Inc. +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2017 Free Software Foundation, Inc. - Permission is granted to copy, distribute and/or modify this document +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". +license is included in the section entitled "GNU +Free Documentation License". (a) The FSF's Front-Cover Text is: - A GNU Manual +A GNU Manual (b) The FSF's Back-Cover Text is: - You have freedom to copy and modify this GNU Manual, like GNU +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> + funds for GNU development. --> +<!-- Created by GNU Texinfo 6.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>Installing GCC</title> + +<meta name="description" content="Installing GCC"> +<meta name="keywords" content="Installing GCC"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.indentedblock {margin-right: 0em} +blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smalllisp {margin-left: 3.2em} +kbd {font-style: oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nolinebreak {white-space: nowrap} +span.roman {font-family: initial; font-weight: normal} +span.sansserif {font-family: sans-serif; font-weight: normal} +ul.no-bullet {list-style: none} +--> +</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 +<body lang="en"> +<h1 class="settitle" align="center">Installing GCC</h1> + + + + + + + + + + + + + + + + + + + + +<a name="index-Installing-GCC_003a-Building"></a> + +<p>Now that GCC is configured, you are ready to build the compiler and +runtime libraries. +</p> +<p>Some commands executed when making the compiler may fail (return a +nonzero status) and be ignored by <code>make</code>. 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. +</p> +<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 +<samp>--disable-werror</samp>. +</p> +<p>On certain old systems, defining certain environment variables such as +<code>CC</code> can interfere with the functioning of <code>make</code>. +</p> +<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 +</p> +<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 <code>fixincludes</code> 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 +<samp>sys/types.h</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 +</p> +<p>The solution is not to use such a directory for building GCC. +</p> +<p>Similarly, when building from SVN or snapshots, or if you modify +<samp>*.l</samp> files, you need the Flex lexical analyzer generator +installed. If you do not modify <samp>*.l</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 +</p> +<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> +<a name="Building-a-native-compiler"></a> +<h3 class="section">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. +a 3-stage bootstrap of the compiler when ‘<samp>make</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 +itself correctly. It can be disabled with the <samp>--disable-bootstrap</samp> +parameter to ‘<samp>configure</samp>’, but bootstrapping is suggested because the compiler will be tested more completely and could also have better performance. +</p> +<p>The bootstrapping process will complete the following steps: +</p> +<ul> +<li> Build tools necessary to build the compiler. - <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 +</li><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><li> Perform a comparison test of the stage2 and stage3 compilers. - <li>Build runtime libraries using the stage3 compiler from the previous step. +</li><li> Build runtime libraries using the stage3 compiler from the previous step. - </ul> +</li></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 +<p>If you are short on disk space you might consider ‘<samp>make +bootstrap-lean</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 +</p> +<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 +doing ‘<samp>make</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.) +</p> +<div class="smallexample"> +<pre class="smallexample">make BOOT_CFLAGS='-O' bootstrap +</pre></div> -<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 +<p>You can place non-default optimization flags into <code>BOOT_CFLAGS</code>; they +are less well tested here than the default of ‘<samp>-g -O2</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, +flags such as <samp>-msoft-float</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. +of the stage1 compiler that were miscompiled, or by using ‘<samp>make +bootstrap4</samp>’ to increase the number of stages of bootstrap. +</p> +<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. +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 +</p> +<p>If you used the flag <samp>--enable-languages=…</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>’ +that re-defining <code>LANGUAGES</code> when calling ‘<samp>make</samp>’ <strong>does not</strong> work anymore! - - <p>If the comparison of stage2 and stage3 fails, this normally indicates +</p> +<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 +need to disable comparison in the <samp>Makefile</samp>.) +</p> +<p>If you do not want to bootstrap your compiler, you can configure with +<samp>--disable-bootstrap</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 +<samp>--enable-bootstrap</samp> to the configure script. +</p> +<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>config/<code>NAME</code>.mk</samp> will +be included by the top-level <samp>Makefile</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 +configure option <samp>--with-build-config=<code>NAME</code>...</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 +</p> +<dl compact="compact"> +<dt>‘<samp>bootstrap-O1</samp>’</dt> +<dd><p>Removes any <samp>-O</samp>-started option from <code>BOOT_CFLAGS</code>, and adds +<samp>-O1</samp> to it. ‘<samp>BUILD_CONFIG=bootstrap-O1</samp>’ is equivalent to +‘<samp>BOOT_CFLAGS='-g -O1'</samp>’. +</p> +</dd> +<dt>‘<samp>bootstrap-O3</samp>’</dt> +<dd><p>Analogous to <code>bootstrap-O1</code>. +</p> +</dd> +<dt>‘<samp>bootstrap-lto</samp>’</dt> +<dd><p>Enables Link-Time Optimization for host tools during bootstrapping. +‘<samp>BUILD_CONFIG=bootstrap-lto</samp>’ is equivalent to adding +<samp>-flto</samp> to ‘<samp>BOOT_CFLAGS</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 +</p> +</dd> +<dt>‘<samp>bootstrap-lto-noplugin</samp>’</dt> +<dd><p>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>libbackend.a</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 +</p> +</dd> +<dt>‘<samp>bootstrap-debug</samp>’</dt> +<dd><p>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 +<samp>contrib/compare-debug</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 +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 +</p> +</dd> +<dt>‘<samp>bootstrap-debug-big</samp>’</dt> +<dd><p>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>, +space. It can be specified in addition to ‘<samp>bootstrap-debug</samp>’. +</p> +</dd> +<dt>‘<samp>bootstrap-debug-lean</samp>’</dt> +<dd><p>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 +<samp>-fcompare-debug</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 +</p> +</dd> +<dt>‘<samp>bootstrap-debug-lib</samp>’</dt> +<dd><p>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 +<samp>-fcompare-debug</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 +</p> +<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 +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 +</p> +</dd> +<dt>‘<samp>bootstrap-debug-ckovw</samp>’</dt> +<dd><p>Arranges for error messages to be issued if the compiler built on any +stage is run without the option <samp>-fcompare-debug</samp>. This is +useful to verify the full <samp>-fcompare-debug</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 +</p> +</dd> +<dt>‘<samp>bootstrap-time</samp>’</dt> +<dd><p>Arranges for the run time of each program started by the GCC driver, +built in any stage, to be logged to <samp>time.log</samp>, in the top level of the build tree. +</p> +</dd> +</dl> - </dl> - -<h3 class="section"><a name="TOC1"></a>Building a cross compiler</h3> +<a name="Building-a-cross-compiler"></a> +<h3 class="section">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 +</p> +<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 +</p> +<p>Assuming you have already installed a native copy of GCC and configured +your cross compiler, issue the command <code>make</code>, which performs the following steps: +</p> +<ul> +<li> Build host tools necessary to build the compiler. - <ul> -<li>Build host tools necessary to build the compiler. - - <li>Build target tools for use by the compiler such as binutils (bfd, +</li><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> +</li><li> Build the compiler (single stage only). - <p>Note that if an error occurs in any step the make process will exit. +</li><li> Build runtime libraries using the compiler from the previous step. +</li></ul> - <p>If you are not building GNU binutils in the same source tree as GCC, +<p>Note that if an error occurs in any step the make process will exit. +</p> +<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 +<samp><var>prefix</var>/<var>target</var>/bin</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. +</p> +<dl compact="compact"> +<dt><samp>as</samp></dt> +<dd><p>This should be the cross-assembler. +</p> +</dd> +<dt><samp>ld</samp></dt> +<dd><p>This should be the cross-linker. +</p> +</dd> +<dt><samp>ar</samp></dt> +<dd><p>This should be the cross-archiver: a program which can manipulate +archive files (linker libraries) in the target machine’s format. +</p> +</dd> +<dt><samp>ranlib</samp></dt> +<dd><p>This should be a program to construct a symbol table in an archive file. +</p></dd> </dl> - <p>The installation of GCC will find these programs in that directory, +<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> +</p> +<p>The easiest way to provide these files is to build the Binutils package. +Configure it with the same <samp>--host</samp> and <samp>--target</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, +</p> +<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 +<samp>--with-sysroot</samp> or <samp>--with-headers</samp> and +<samp>--with-libs</samp>. Many targets also require “start files” such +as <samp>crt0.o</samp> and +<samp>crtn.o</samp> which are linked into each executable. There may be several +alternatives for <samp>crt0.o</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> +<a name="Building-in-parallel"></a> +<h3 class="section">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 +building in parallel. To activate this, you can use ‘<samp>make -j 2</samp>’ +instead of ‘<samp>make</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> +<a name="Building-the-Ada-compiler"></a> +<h3 class="section">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 +compiler (GCC version 4.0 or later). +This includes GNAT tools such as <code>gnatmake</code> and +<code>gnatlink</code>, 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 +</p> +<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 +</p> +<p><code>configure</code> 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 +installed, the build will fail unless <samp>--enable-languages</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 +</p> +<p><code>ADA_INCLUDE_PATH</code> and <code>ADA_OBJECT_PATH</code> 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 +by verifying that ‘<samp>gnatls -v</samp>’ lists only one explicit path in each section. - -<h3 class="section"><a name="TOC4"></a>Building with profile feedback</h3> +</p> +<a name="Building-with-profile-feedback"></a> +<h3 class="section">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> +</p> +<p>When ‘<samp>make profiledbootstrap</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. +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. +</p> +<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> +<p>On Linux/x86_64 hosts with some restrictions (no virtualization) it is +also possible to do autofdo build with ‘<samp>make +autoprofiledback</samp>’. This uses Linux perf to sample branches in the +binary and then rebuild it with feedback derived from the profile. +Linux perf and the <code>autofdo</code> toolkit needs to be installed for +this. +</p> +<p>Only the profile from the current build is used, so when an error +occurs it is recommended to clean before restarting. Otherwise +the code quality may be much worse. +</p> +<hr /> +<p> <p><a href="./index.html">Return to the GCC Installation page</a> +</p> + + + + + + + +<hr> + -<!-- ***Testing***************************************************************** --> -<!-- ***Final install*********************************************************** --> -<!-- ***Binaries**************************************************************** --> -<!-- ***Specific**************************************************************** --> -<!-- ***Old documentation****************************************************** --> -<!-- ***GFDL******************************************************************** --> -<!-- *************************************************************************** --> -<!-- Part 6 The End of the Document --> -</body></html> +</body> +</html> |