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1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- Copyright (C) 1988-2013 Free Software Foundation, Inc. 4 5Permission is granted to copy, distribute and/or modify this document 6under the terms of the GNU Free Documentation License, Version 1.3 or 7any later version published by the Free Software Foundation; with no 8Invariant Sections, the Front-Cover texts being (a) (see below), and 9with the Back-Cover Texts being (b) (see below). A copy of the 10license is included in the section entitled "GNU 11Free Documentation License". 12 13(a) The FSF's Front-Cover Text is: 14 15A GNU Manual 16 17(b) The FSF's Back-Cover Text is: 18 19You have freedom to copy and modify this GNU Manual, like GNU 20 software. Copies published by the Free Software Foundation raise 21 funds for GNU development. --> 22<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ --> 23<head> 24<title>Installing GCC</title> 25 26<meta name="description" content="Installing GCC"> 27<meta name="keywords" content="Installing GCC"> 28<meta name="resource-type" content="document"> 29<meta name="distribution" content="global"> 30<meta name="Generator" content="makeinfo"> 31<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 32<style type="text/css"> 33<!-- 34a.summary-letter {text-decoration: none} 35blockquote.smallquotation {font-size: smaller} 36div.display {margin-left: 3.2em} 37div.example {margin-left: 3.2em} 38div.indentedblock {margin-left: 3.2em} 39div.lisp {margin-left: 3.2em} 40div.smalldisplay {margin-left: 3.2em} 41div.smallexample {margin-left: 3.2em} 42div.smallindentedblock {margin-left: 3.2em; font-size: smaller} 43div.smalllisp {margin-left: 3.2em} 44kbd {font-style:oblique} 45pre.display {font-family: inherit} 46pre.format {font-family: inherit} 47pre.menu-comment {font-family: serif} 48pre.menu-preformatted {font-family: serif} 49pre.smalldisplay {font-family: inherit; font-size: smaller} 50pre.smallexample {font-size: smaller} 51pre.smallformat {font-family: inherit; font-size: smaller} 52pre.smalllisp {font-size: smaller} 53span.nocodebreak {white-space:nowrap} 54span.nolinebreak {white-space:nowrap} 55span.roman {font-family:serif; font-weight:normal} 56span.sansserif {font-family:sans-serif; font-weight:normal} 57ul.no-bullet {list-style: none} 58--> 59</style> 60 61 62</head> 63 64<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> 65<h1 class="settitle" align="center">Installing GCC</h1> 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86<a name="index-Installing-GCC_003a-Building"></a> 87 88<p>Now that GCC is configured, you are ready to build the compiler and 89runtime libraries. 90</p> 91<p>Some commands executed when making the compiler may fail (return a 92nonzero status) and be ignored by <code>make</code>. These failures, which 93are often due to files that were not found, are expected, and can safely 94be ignored. 95</p> 96<p>It is normal to have compiler warnings when compiling certain files. 97Unless you are a GCC developer, you can generally ignore these warnings 98unless they cause compilation to fail. Developers should attempt to fix 99any warnings encountered, however they can temporarily continue past 100warnings-as-errors by specifying the configure flag 101<samp>--disable-werror</samp>. 102</p> 103<p>On certain old systems, defining certain environment variables such as 104<code>CC</code> can interfere with the functioning of <code>make</code>. 105</p> 106<p>If you encounter seemingly strange errors when trying to build the 107compiler in a directory other than the source directory, it could be 108because you have previously configured the compiler in the source 109directory. Make sure you have done all the necessary preparations. 110</p> 111<p>If you build GCC on a BSD system using a directory stored in an old System 112V file system, problems may occur in running <code>fixincludes</code> if the 113System V file system doesn’t support symbolic links. These problems 114result in a failure to fix the declaration of <code>size_t</code> in 115<samp>sys/types.h</samp>. If you find that <code>size_t</code> is a signed type and 116that type mismatches occur, this could be the cause. 117</p> 118<p>The solution is not to use such a directory for building GCC. 119</p> 120<p>Similarly, when building from SVN or snapshots, or if you modify 121<samp>*.l</samp> files, you need the Flex lexical analyzer generator 122installed. If you do not modify <samp>*.l</samp> files, releases contain 123the Flex-generated files and you do not need Flex installed to build 124them. There is still one Flex-based lexical analyzer (part of the 125build machinery, not of GCC itself) that is used even if you only 126build the C front end. 127</p> 128<p>When building from SVN or snapshots, or if you modify Texinfo 129documentation, you need version 4.7 or later of Texinfo installed if you 130want Info documentation to be regenerated. Releases contain Info 131documentation pre-built for the unmodified documentation in the release. 132</p> 133<a name="Building-a-native-compiler"></a> 134<h3 class="section">Building a native compiler</h3> 135 136<p>For a native build, the default configuration is to perform 137a 3-stage bootstrap of the compiler when ‘<samp>make</samp>’ is invoked. 138This will build the entire GCC system and ensure that it compiles 139itself correctly. It can be disabled with the <samp>--disable-bootstrap</samp> 140parameter to ‘<samp>configure</samp>’, but bootstrapping is suggested because 141the compiler will be tested more completely and could also have 142better performance. 143</p> 144<p>The bootstrapping process will complete the following steps: 145</p> 146<ul> 147<li> Build tools necessary to build the compiler. 148 149</li><li> Perform a 3-stage bootstrap of the compiler. This includes building 150three times the target tools for use by the compiler such as binutils 151(bfd, binutils, gas, gprof, ld, and opcodes) if they have been 152individually linked or moved into the top level GCC source tree before 153configuring. 154 155</li><li> Perform a comparison test of the stage2 and stage3 compilers. 156 157</li><li> Build runtime libraries using the stage3 compiler from the previous step. 158 159</li></ul> 160 161<p>If you are short on disk space you might consider ‘<samp>make 162bootstrap-lean</samp>’ instead. The sequence of compilation is the 163same described above, but object files from the stage1 and 164stage2 of the 3-stage bootstrap of the compiler are deleted as 165soon as they are no longer needed. 166</p> 167<p>If you wish to use non-default GCC flags when compiling the stage2 168and stage3 compilers, set <code>BOOT_CFLAGS</code> on the command line when 169doing ‘<samp>make</samp>’. For example, if you want to save additional space 170during the bootstrap and in the final installation as well, you can 171build the compiler binaries without debugging information as in the 172following example. This will save roughly 40% of disk space both for 173the bootstrap and the final installation. (Libraries will still contain 174debugging information.) 175</p> 176<div class="smallexample"> 177<pre class="smallexample">make BOOT_CFLAGS='-O' bootstrap 178</pre></div> 179 180<p>You can place non-default optimization flags into <code>BOOT_CFLAGS</code>; they 181are less well tested here than the default of ‘<samp>-g -O2</samp>’, but should 182still work. In a few cases, you may find that you need to specify special 183flags such as <samp>-msoft-float</samp> here to complete the bootstrap; or, 184if the native compiler miscompiles the stage1 compiler, you may need 185to work around this, by choosing <code>BOOT_CFLAGS</code> to avoid the parts 186of the stage1 compiler that were miscompiled, or by using ‘<samp>make 187bootstrap4</samp>’ to increase the number of stages of bootstrap. 188</p> 189<p><code>BOOT_CFLAGS</code> does not apply to bootstrapped target libraries. 190Since these are always compiled with the compiler currently being 191bootstrapped, you can use <code>CFLAGS_FOR_TARGET</code> to modify their 192compilation flags, as for non-bootstrapped target libraries. 193Again, if the native compiler miscompiles the stage1 compiler, you may 194need to work around this by avoiding non-working parts of the stage1 195compiler. Use <code>STAGE1_TFLAGS</code> to this end. 196</p> 197<p>If you used the flag <samp>--enable-languages=…</samp> to restrict 198the compilers to be built, only those you’ve actually enabled will be 199built. This will of course only build those runtime libraries, for 200which the particular compiler has been built. Please note, 201that re-defining <code>LANGUAGES</code> when calling ‘<samp>make</samp>’ 202<strong>does not</strong> work anymore! 203</p> 204<p>If the comparison of stage2 and stage3 fails, this normally indicates 205that the stage2 compiler has compiled GCC incorrectly, and is therefore 206a potentially serious bug which you should investigate and report. (On 207a few systems, meaningful comparison of object files is impossible; they 208always appear “different”. If you encounter this problem, you will 209need to disable comparison in the <samp>Makefile</samp>.) 210</p> 211<p>If you do not want to bootstrap your compiler, you can configure with 212<samp>--disable-bootstrap</samp>. In particular cases, you may want to 213bootstrap your compiler even if the target system is not the same as 214the one you are building on: for example, you could build a 215<code>powerpc-unknown-linux-gnu</code> toolchain on a 216<code>powerpc64-unknown-linux-gnu</code> host. In this case, pass 217<samp>--enable-bootstrap</samp> to the configure script. 218</p> 219<p><code>BUILD_CONFIG</code> can be used to bring in additional customization 220to the build. It can be set to a whitespace-separated list of names. 221For each such <code>NAME</code>, top-level <samp>config/<code>NAME</code>.mk</samp> will 222be included by the top-level <samp>Makefile</samp>, bringing in any settings 223it contains. The default <code>BUILD_CONFIG</code> can be set using the 224configure option <samp>--with-build-config=<code>NAME</code>...</samp>. Some 225examples of supported build configurations are: 226</p> 227<dl compact="compact"> 228<dt>‘<samp>bootstrap-O1</samp>’</dt> 229<dd><p>Removes any <samp>-O</samp>-started option from <code>BOOT_CFLAGS</code>, and adds 230<samp>-O1</samp> to it. ‘<samp>BUILD_CONFIG=bootstrap-O1</samp>’ is equivalent to 231‘<samp>BOOT_CFLAGS='-g -O1'</samp>’. 232</p> 233</dd> 234<dt>‘<samp>bootstrap-O3</samp>’</dt> 235<dd><p>Analogous to <code>bootstrap-O1</code>. 236</p> 237</dd> 238<dt>‘<samp>bootstrap-lto</samp>’</dt> 239<dd><p>Enables Link-Time Optimization for host tools during bootstrapping. 240‘<samp>BUILD_CONFIG=bootstrap-lto</samp>’ is equivalent to adding 241<samp>-flto</samp> to ‘<samp>BOOT_CFLAGS</samp>’. 242</p> 243</dd> 244<dt>‘<samp>bootstrap-debug</samp>’</dt> 245<dd><p>Verifies that the compiler generates the same executable code, whether 246or not it is asked to emit debug information. To this end, this 247option builds stage2 host programs without debug information, and uses 248<samp>contrib/compare-debug</samp> to compare them with the stripped stage3 249object files. If <code>BOOT_CFLAGS</code> is overridden so as to not enable 250debug information, stage2 will have it, and stage3 won’t. This option 251is enabled by default when GCC bootstrapping is enabled, if 252<code>strip</code> can turn object files compiled with and without debug 253info into identical object files. In addition to better test 254coverage, this option makes default bootstraps faster and leaner. 255</p> 256</dd> 257<dt>‘<samp>bootstrap-debug-big</samp>’</dt> 258<dd><p>Rather than comparing stripped object files, as in 259<code>bootstrap-debug</code>, this option saves internal compiler dumps 260during stage2 and stage3 and compares them as well, which helps catch 261additional potential problems, but at a great cost in terms of disk 262space. It can be specified in addition to ‘<samp>bootstrap-debug</samp>’. 263</p> 264</dd> 265<dt>‘<samp>bootstrap-debug-lean</samp>’</dt> 266<dd><p>This option saves disk space compared with <code>bootstrap-debug-big</code>, 267but at the expense of some recompilation. Instead of saving the dumps 268of stage2 and stage3 until the final compare, it uses 269<samp>-fcompare-debug</samp> to generate, compare and remove the dumps 270during stage3, repeating the compilation that already took place in 271stage2, whose dumps were not saved. 272</p> 273</dd> 274<dt>‘<samp>bootstrap-debug-lib</samp>’</dt> 275<dd><p>This option tests executable code invariance over debug information 276generation on target libraries, just like <code>bootstrap-debug-lean</code> 277tests it on host programs. It builds stage3 libraries with 278<samp>-fcompare-debug</samp>, and it can be used along with any of the 279<code>bootstrap-debug</code> options above. 280</p> 281<p>There aren’t <code>-lean</code> or <code>-big</code> counterparts to this option 282because most libraries are only build in stage3, so bootstrap compares 283would not get significant coverage. Moreover, the few libraries built 284in stage2 are used in stage3 host programs, so we wouldn’t want to 285compile stage2 libraries with different options for comparison purposes. 286</p> 287</dd> 288<dt>‘<samp>bootstrap-debug-ckovw</samp>’</dt> 289<dd><p>Arranges for error messages to be issued if the compiler built on any 290stage is run without the option <samp>-fcompare-debug</samp>. This is 291useful to verify the full <samp>-fcompare-debug</samp> testing coverage. It 292must be used along with <code>bootstrap-debug-lean</code> and 293<code>bootstrap-debug-lib</code>. 294</p> 295</dd> 296<dt>‘<samp>bootstrap-time</samp>’</dt> 297<dd><p>Arranges for the run time of each program started by the GCC driver, 298built in any stage, to be logged to <samp>time.log</samp>, in the top level of 299the build tree. 300</p> 301</dd> 302</dl> 303 304<a name="Building-a-cross-compiler"></a> 305<h3 class="section">Building a cross compiler</h3> 306 307<p>When building a cross compiler, it is not generally possible to do a 3083-stage bootstrap of the compiler. This makes for an interesting problem 309as parts of GCC can only be built with GCC. 310</p> 311<p>To build a cross compiler, we recommend first building and installing a 312native compiler. You can then use the native GCC compiler to build the 313cross compiler. The installed native compiler needs to be GCC version 3142.95 or later. 315</p> 316<p>If the cross compiler is to be built with support for the Java 317programming language and the ability to compile .java source files is 318desired, the installed native compiler used to build the cross 319compiler needs to be the same GCC version as the cross compiler. In 320addition the cross compiler needs to be configured with 321<samp>--with-ecj-jar=…</samp>. 322</p> 323<p>Assuming you have already installed a native copy of GCC and configured 324your cross compiler, issue the command <code>make</code>, which performs the 325following steps: 326</p> 327<ul> 328<li> Build host tools necessary to build the compiler. 329 330</li><li> Build target tools for use by the compiler such as binutils (bfd, 331binutils, gas, gprof, ld, and opcodes) 332if they have been individually linked or moved into the top level GCC source 333tree before configuring. 334 335</li><li> Build the compiler (single stage only). 336 337</li><li> Build runtime libraries using the compiler from the previous step. 338</li></ul> 339 340<p>Note that if an error occurs in any step the make process will exit. 341</p> 342<p>If you are not building GNU binutils in the same source tree as GCC, 343you will need a cross-assembler and cross-linker installed before 344configuring GCC. Put them in the directory 345<samp><var>prefix</var>/<var>target</var>/bin</samp>. Here is a table of the tools 346you should put in this directory: 347</p> 348<dl compact="compact"> 349<dt><samp>as</samp></dt> 350<dd><p>This should be the cross-assembler. 351</p> 352</dd> 353<dt><samp>ld</samp></dt> 354<dd><p>This should be the cross-linker. 355</p> 356</dd> 357<dt><samp>ar</samp></dt> 358<dd><p>This should be the cross-archiver: a program which can manipulate 359archive files (linker libraries) in the target machine’s format. 360</p> 361</dd> 362<dt><samp>ranlib</samp></dt> 363<dd><p>This should be a program to construct a symbol table in an archive file. 364</p></dd> 365</dl> 366 367<p>The installation of GCC will find these programs in that directory, 368and copy or link them to the proper place to for the cross-compiler to 369find them when run later. 370</p> 371<p>The easiest way to provide these files is to build the Binutils package. 372Configure it with the same <samp>--host</samp> and <samp>--target</samp> 373options that you use for configuring GCC, then build and install 374them. They install their executables automatically into the proper 375directory. Alas, they do not support all the targets that GCC 376supports. 377</p> 378<p>If you are not building a C library in the same source tree as GCC, 379you should also provide the target libraries and headers before 380configuring GCC, specifying the directories with 381<samp>--with-sysroot</samp> or <samp>--with-headers</samp> and 382<samp>--with-libs</samp>. Many targets also require “start files” such 383as <samp>crt0.o</samp> and 384<samp>crtn.o</samp> which are linked into each executable. There may be several 385alternatives for <samp>crt0.o</samp>, for use with profiling or other 386compilation options. Check your target’s definition of 387<code>STARTFILE_SPEC</code> to find out what start files it uses. 388</p> 389<a name="Building-in-parallel"></a> 390<h3 class="section">Building in parallel</h3> 391 392<p>GNU Make 3.80 and above, which is necessary to build GCC, support 393building in parallel. To activate this, you can use ‘<samp>make -j 2</samp>’ 394instead of ‘<samp>make</samp>’. You can also specify a bigger number, and 395in most cases using a value greater than the number of processors in 396your machine will result in fewer and shorter I/O latency hits, thus 397improving overall throughput; this is especially true for slow drives 398and network filesystems. 399</p> 400<a name="Building-the-Ada-compiler"></a> 401<h3 class="section">Building the Ada compiler</h3> 402 403<p>In order to build GNAT, the Ada compiler, you need a working GNAT 404compiler (GCC version 4.0 or later). 405This includes GNAT tools such as <code>gnatmake</code> and 406<code>gnatlink</code>, since the Ada front end is written in Ada and 407uses some GNAT-specific extensions. 408</p> 409<p>In order to build a cross compiler, it is suggested to install 410the new compiler as native first, and then use it to build the cross 411compiler. 412</p> 413<p><code>configure</code> does not test whether the GNAT installation works 414and has a sufficiently recent version; if too old a GNAT version is 415installed, the build will fail unless <samp>--enable-languages</samp> is 416used to disable building the Ada front end. 417</p> 418<p><code>ADA_INCLUDE_PATH</code> and <code>ADA_OBJECT_PATH</code> environment variables 419must not be set when building the Ada compiler, the Ada tools, or the 420Ada runtime libraries. You can check that your build environment is clean 421by verifying that ‘<samp>gnatls -v</samp>’ lists only one explicit path in each 422section. 423</p> 424<a name="Building-with-profile-feedback"></a> 425<h3 class="section">Building with profile feedback</h3> 426 427<p>It is possible to use profile feedback to optimize the compiler itself. This 428should result in a faster compiler binary. Experiments done on x86 using gcc 4293.3 showed approximately 7 percent speedup on compiling C programs. To 430bootstrap the compiler with profile feedback, use <code>make profiledbootstrap</code>. 431</p> 432<p>When ‘<samp>make profiledbootstrap</samp>’ is run, it will first build a <code>stage1</code> 433compiler. This compiler is used to build a <code>stageprofile</code> compiler 434instrumented to collect execution counts of instruction and branch 435probabilities. Then runtime libraries are compiled with profile collected. 436Finally a <code>stagefeedback</code> compiler is built using the information collected. 437</p> 438<p>Unlike standard bootstrap, several additional restrictions apply. The 439compiler used to build <code>stage1</code> needs to support a 64-bit integral type. 440It is recommended to only use GCC for this. Also parallel make is currently 441not supported since collisions in profile collecting may occur. 442</p> 443<hr /> 444<p><p><a href="./index.html">Return to the GCC Installation page</a> 445</p> 446 447 448 449 450 451 452 453<hr> 454 455 456 457</body> 458</html> 459