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Copies published by the Free Software Foundation raise - funds for GNU development. --> -<!-- Created by GNU Texinfo 5.1, 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.smallquotation {font-size: smaller} -div.display {margin-left: 3.2em} -div.example {margin-left: 3.2em} -div.indentedblock {margin-left: 3.2em} -div.lisp {margin-left: 3.2em} -div.smalldisplay {margin-left: 3.2em} -div.smallexample {margin-left: 3.2em} -div.smallindentedblock {margin-left: 3.2em; font-size: smaller} -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.nocodebreak {white-space:nowrap} -span.nolinebreak {white-space:nowrap} -span.roman {font-family:serif; font-weight:normal} -span.sansserif {font-family:sans-serif; font-weight:normal} -ul.no-bullet {list-style: none} ---> -</style> - - -</head> - -<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> -<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> -<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>--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> -<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>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> -<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> -<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. -</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>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>--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. - -</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><li> Perform a comparison test of the stage2 and stage3 compilers. - -</li><li> Build runtime libraries using the stage3 compiler from the previous step. - -</li></ul> - -<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> -<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>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> - -<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>-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>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. -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> -<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 <code>LANGUAGES</code> when calling ‘<samp>make</samp>’ -<strong>does not</strong> work anymore! -</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>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>--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>--with-build-config=<code>NAME</code>...</samp>. Some -examples of supported build configurations are: -</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>’. -</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>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 -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. -</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>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>-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. -</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>-fcompare-debug</samp>, and it can be used along with any of the -<code>bootstrap-debug</code> options above. -</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 -compile stage2 libraries with different options for comparison purposes. -</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>. -</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> - -<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> -<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> -<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>--with-ecj-jar=…</samp>. -</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. - -</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><li> Build the compiler (single stage only). - -</li><li> Build runtime libraries using the compiler from the previous step. -</li></ul> - -<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>/<var>target</var>/bin</samp>. Here is a table of the tools -you should put in this directory: -</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, -and copy or link them to the proper place to for the cross-compiler to -find them when run later. -</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> -<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>--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. -</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>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. -</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 <code>gnatmake</code> and -<code>gnatlink</code>, since the Ada front end is written in Ada and -uses some GNAT-specific extensions. -</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> -<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>--enable-languages</samp> is -used to disable building the Ada front end. -</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>gnatls -v</samp>’ lists only one explicit path in each -section. -</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> -<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. -Finally a <code>stagefeedback</code> compiler is built using the information collected. -</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. Also parallel make is currently -not supported since collisions in profile collecting may occur. -</p> -<hr /> -<p><p><a href="./index.html">Return to the GCC Installation page</a> -</p> - - - - - - - -<hr> - - - -</body> -</html> |