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  1. <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

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  9. with the Back-Cover Texts being (b) (see below).  A copy of the

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  13. (a) The FSF's Front-Cover Text is:

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  15. A GNU Manual

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  25. <title>Installing GCC: Configuration</title>

  26. 

  27. <meta name="description" content="Installing GCC: Configuration">

  28. <meta name="keywords" content="Installing GCC: Configuration">

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  58. </style>

  59. 

  60. 

  61. </head>

  62. 

  63. <body lang="en">

  64. <h1 class="settitle" align="center">Installing GCC: Configuration</h1>

  65. 

  66. 

  67. 

  68. 

  69. 

  70. 

  71. 

  72. 

  73. 

  74. 

  75. 

  76. 

  77. 

  78. 

  79. 

  80. 

  81. 

  82. 

  83. 

  84. <a name="index-Configuration"></a>

  85. <a name="index-Installing-GCC_003a-Configuration"></a>

  86. 

  87. <p>Like most GNU software, GCC must be configured before it can be built.

  88. This document describes the recommended configuration procedure

  89. for both native and cross targets.

  90. </p>

  91. <p>We use <var>srcdir</var> to refer to the toplevel source directory for

  92. GCC; we use <var>objdir</var> to refer to the toplevel build/object directory.

  93. </p>

  94. <p>If you obtained the sources by cloning the repository, <var>srcdir</var>

  95. must refer to the top <samp>gcc</samp> directory, the one where the

  96. <samp>MAINTAINERS</samp> file can be found, and not its <samp>gcc</samp>

  97. subdirectory, otherwise the build will fail.

  98. </p>

  99. <p>If either <var>srcdir</var> or <var>objdir</var> is located on an automounted NFS

  100. file system, the shell&rsquo;s built-in <code>pwd</code> command will return

  101. temporary pathnames.  Using these can lead to various sorts of build

  102. problems.  To avoid this issue, set the <code>PWDCMD</code> environment

  103. variable to an automounter-aware <code>pwd</code> command, e.g.,

  104. <code>pawd</code> or &lsquo;<samp>amq -w</samp>&rsquo;, during the configuration and build

  105. phases.

  106. </p>

  107. <p>First, we <strong>highly</strong> recommend that GCC be built into a

  108. separate directory from the sources which does <strong>not</strong> reside

  109. within the source tree.  This is how we generally build GCC; building

  110. where <var>srcdir</var> == <var>objdir</var> should still work, but doesn&rsquo;t

  111. get extensive testing; building where <var>objdir</var> is a subdirectory

  112. of <var>srcdir</var> is unsupported.

  113. </p>

  114. <p>If you have previously built GCC in the same directory for a

  115. different target machine, do &lsquo;<samp>make distclean</samp>&rsquo; to delete all files

  116. that might be invalid.  One of the files this deletes is <samp>Makefile</samp>;

  117. if &lsquo;<samp>make distclean</samp>&rsquo; complains that <samp>Makefile</samp> does not exist

  118. or issues a message like &ldquo;don&rsquo;t know how to make distclean&rdquo; it probably

  119. means that the directory is already suitably clean.  However, with the

  120. recommended method of building in a separate <var>objdir</var>, you should

  121. simply use a different <var>objdir</var> for each target.

  122. </p>

  123. <p>Second, when configuring a native system, either <code>cc</code> or

  124. <code>gcc</code> must be in your path or you must set <code>CC</code> in

  125. your environment before running configure.  Otherwise the configuration

  126. scripts may fail.

  127. </p>

  128. 

  129. <p>To configure GCC:

  130. </p>

  131. <div class="smallexample">

  132. <pre class="smallexample">% mkdir <var>objdir</var>

  133. % cd <var>objdir</var>

  134. % <var>srcdir</var>/configure [<var>options</var>] [<var>target</var>]

  135. </pre></div>

  136. 

  137. <a name="Distributor-options"></a>

  138. <h3 class="heading">Distributor options</h3>

  139. 

  140. <p>If you will be distributing binary versions of GCC, with modifications

  141. to the source code, you should use the options described in this

  142. section to make clear that your version contains modifications.

  143. </p>

  144. <dl compact="compact">

  145. <dt><code>--with-pkgversion=<var>version</var></code></dt>

  146. <dd><p>Specify a string that identifies your package.  You may wish

  147. to include a build number or build date.  This version string will be

  148. included in the output of <code>gcc --version</code>.  This suffix does

  149. not replace the default version string, only the &lsquo;<samp>GCC</samp>&rsquo; part.

  150. </p>

  151. <p>The default value is &lsquo;<samp>GCC</samp>&rsquo;.

  152. </p>

  153. </dd>

  154. <dt><code>--with-bugurl=<var>url</var></code></dt>

  155. <dd><p>Specify the URL that users should visit if they wish to report a bug.

  156. You are of course welcome to forward bugs reported to you to the FSF,

  157. if you determine that they are not bugs in your modifications.

  158. </p>

  159. <p>The default value refers to the FSF&rsquo;s GCC bug tracker.

  160. </p>

  161. </dd>

  162. <dt><code>--with-documentation-root-url=<var>url</var></code></dt>

  163. <dd><p>Specify the URL root that contains GCC option documentation.  The <var>url</var>

  164. should end with a <code>/</code> character.

  165. </p>

  166. <p>The default value is <a href="https://gcc.gnu.org/onlinedocs/">https://gcc.gnu.org/onlinedocs/</a>.

  167. </p>

  168. </dd>

  169. <dt><code>--with-changes-root-url=<var>url</var></code></dt>

  170. <dd><p>Specify the URL root that contains information about changes in GCC

  171. releases like <code>gcc-<var>version</var>/changes.html</code>.

  172. The <var>url</var> should end with a <code>/</code> character.

  173. </p>

  174. <p>The default value is <a href="https://gcc.gnu.org/">https://gcc.gnu.org/</a>.

  175. </p>

  176. </dd>

  177. </dl>

  178. 

  179. <a name="Target-specification"></a>

  180. <h3 class="heading">Target specification</h3>

  181. <ul>

  182. <li> GCC has code to correctly determine the correct value for <var>target</var>

  183. for nearly all native systems.  Therefore, we highly recommend you do

  184. not provide a configure target when configuring a native compiler.

  185. 

  186. </li><li> <var>target</var> must be specified as <samp>--target=<var>target</var></samp>

  187. when configuring a cross compiler; examples of valid targets would be

  188. m68k-elf, sh-elf, etc.

  189. 

  190. </li><li> Specifying just <var>target</var> instead of <samp>--target=<var>target</var></samp>

  191. implies that the host defaults to <var>target</var>.

  192. </li></ul>

  193. 

  194. 

  195. <a name="Options-specification"></a>

  196. <h3 class="heading">Options specification</h3>

  197. 

  198. <p>Use <var>options</var> to override several configure time options for

  199. GCC.  A list of supported <var>options</var> follows; &lsquo;<samp>configure

  200. --help</samp>&rsquo; may list other options, but those not listed below may not

  201. work and should not normally be used.

  202. </p>

  203. <p>Note that each <samp>--enable</samp> option has a corresponding

  204. <samp>--disable</samp> option and that each <samp>--with</samp> option has a

  205. corresponding <samp>--without</samp> option.

  206. </p>

  207. <dl compact="compact">

  208. <dt><code>--prefix=<var>dirname</var></code></dt>

  209. <dd><p>Specify the toplevel installation

  210. directory.  This is the recommended way to install the tools into a directory

  211. other than the default.  The toplevel installation directory defaults to

  212. <samp>/usr/local</samp>.

  213. </p>

  214. <p>We <strong>highly</strong> recommend against <var>dirname</var> being the same or a

  215. subdirectory of <var>objdir</var> or vice versa.  If specifying a directory

  216. beneath a user&rsquo;s home directory tree, some shells will not expand

  217. <var>dirname</var> correctly if it contains the &lsquo;<samp>~</samp>&rsquo; metacharacter; use

  218. <code>$HOME</code> instead.

  219. </p>

  220. <p>The following standard <code>autoconf</code> options are supported.  Normally you

  221. should not need to use these options.

  222. </p><dl compact="compact">

  223. <dt><code>--exec-prefix=<var>dirname</var></code></dt>

  224. <dd><p>Specify the toplevel installation directory for architecture-dependent

  225. files.  The default is <samp><var>prefix</var></samp>.

  226. </p>

  227. </dd>

  228. <dt><code>--bindir=<var>dirname</var></code></dt>

  229. <dd><p>Specify the installation directory for the executables called by users

  230. (such as <code>gcc</code> and <code>g++</code>).  The default is

  231. <samp><var>exec-prefix</var>/bin</samp>.

  232. </p>

  233. </dd>

  234. <dt><code>--libdir=<var>dirname</var></code></dt>

  235. <dd><p>Specify the installation directory for object code libraries and

  236. internal data files of GCC.  The default is <samp><var>exec-prefix</var>/lib</samp>.

  237. </p>

  238. </dd>

  239. <dt><code>--libexecdir=<var>dirname</var></code></dt>

  240. <dd><p>Specify the installation directory for internal executables of GCC.

  241. The default is <samp><var>exec-prefix</var>/libexec</samp>.

  242. </p>

  243. </dd>

  244. <dt><code>--with-slibdir=<var>dirname</var></code></dt>

  245. <dd><p>Specify the installation directory for the shared libgcc library.  The

  246. default is <samp><var>libdir</var></samp>.

  247. </p>

  248. </dd>

  249. <dt><code>--datarootdir=<var>dirname</var></code></dt>

  250. <dd><p>Specify the root of the directory tree for read-only architecture-independent

  251. data files referenced by GCC.  The default is <samp><var>prefix</var>/share</samp>.

  252. </p>

  253. </dd>

  254. <dt><code>--infodir=<var>dirname</var></code></dt>

  255. <dd><p>Specify the installation directory for documentation in info format.

  256. The default is <samp><var>datarootdir</var>/info</samp>.

  257. </p>

  258. </dd>

  259. <dt><code>--datadir=<var>dirname</var></code></dt>

  260. <dd><p>Specify the installation directory for some architecture-independent

  261. data files referenced by GCC.  The default is <samp><var>datarootdir</var></samp>.

  262. </p>

  263. </dd>

  264. <dt><code>--docdir=<var>dirname</var></code></dt>

  265. <dd><p>Specify the installation directory for documentation files (other

  266. than Info) for GCC.  The default is <samp><var>datarootdir</var>/doc</samp>.

  267. </p>

  268. </dd>

  269. <dt><code>--htmldir=<var>dirname</var></code></dt>

  270. <dd><p>Specify the installation directory for HTML documentation files.

  271. The default is <samp><var>docdir</var></samp>.

  272. </p>

  273. </dd>

  274. <dt><code>--pdfdir=<var>dirname</var></code></dt>

  275. <dd><p>Specify the installation directory for PDF documentation files.

  276. The default is <samp><var>docdir</var></samp>.

  277. </p>

  278. </dd>

  279. <dt><code>--mandir=<var>dirname</var></code></dt>

  280. <dd><p>Specify the installation directory for manual pages.  The default is

  281. <samp><var>datarootdir</var>/man</samp>.  (Note that the manual pages are only extracts

  282. from the full GCC manuals, which are provided in Texinfo format.  The manpages

  283. are derived by an automatic conversion process from parts of the full

  284. manual.)

  285. </p>

  286. </dd>

  287. <dt><code>--with-gxx-include-dir=<var>dirname</var></code></dt>

  288. <dd><p>Specify

  289. the installation directory for G++ header files.  The default depends

  290. on other configuration options, and differs between cross and native

  291. configurations.

  292. </p>

  293. </dd>

  294. <dt><code>--with-specs=<var>specs</var></code></dt>

  295. <dd><p>Specify additional command line driver SPECS.

  296. This can be useful if you need to turn on a non-standard feature by

  297. default without modifying the compiler&rsquo;s source code, for instance

  298. <samp>--with-specs=%{!fcommon:%{!fno-common:-fno-common}}</samp>.

  299. See &ldquo;Spec Files&rdquo; in the main manual

  300. </p>

  301. </dd>

  302. </dl>

  303. 

  304. </dd>

  305. <dt><code>--program-prefix=<var>prefix</var></code></dt>

  306. <dd><p>GCC supports some transformations of the names of its programs when

  307. installing them.  This option prepends <var>prefix</var> to the names of

  308. programs to install in <var>bindir</var> (see above).  For example, specifying

  309. <samp>--program-prefix=foo-</samp> would result in &lsquo;<samp>gcc</samp>&rsquo;

  310. being installed as <samp>/usr/local/bin/foo-gcc</samp>.

  311. </p>

  312. </dd>

  313. <dt><code>--program-suffix=<var>suffix</var></code></dt>

  314. <dd><p>Appends <var>suffix</var> to the names of programs to install in <var>bindir</var>

  315. (see above).  For example, specifying <samp>--program-suffix=-3.1</samp>

  316. would result in &lsquo;<samp>gcc</samp>&rsquo; being installed as

  317. <samp>/usr/local/bin/gcc-3.1</samp>.

  318. </p>

  319. </dd>

  320. <dt><code>--program-transform-name=<var>pattern</var></code></dt>

  321. <dd><p>Applies the &lsquo;<samp>sed</samp>&rsquo; script <var>pattern</var> to be applied to the names

  322. of programs to install in <var>bindir</var> (see above).  <var>pattern</var> has to

  323. consist of one or more basic &lsquo;<samp>sed</samp>&rsquo; editing commands, separated by

  324. semicolons.  For example, if you want the &lsquo;<samp>gcc</samp>&rsquo; program name to be

  325. transformed to the installed program <samp>/usr/local/bin/myowngcc</samp> and

  326. the &lsquo;<samp>g++</samp>&rsquo; program name to be transformed to

  327. <samp>/usr/local/bin/gspecial++</samp> without changing other program names,

  328. you could use the pattern

  329. <samp>--program-transform-name='s/^gcc$/myowngcc/; s/^g++$/gspecial++/'</samp>

  330. to achieve this effect.

  331. </p>

  332. <p>All three options can be combined and used together, resulting in more

  333. complex conversion patterns.  As a basic rule, <var>prefix</var> (and

  334. <var>suffix</var>) are prepended (appended) before further transformations

  335. can happen with a special transformation script <var>pattern</var>.

  336. </p>

  337. <p>As currently implemented, this option only takes effect for native

  338. builds; cross compiler binaries&rsquo; names are not transformed even when a

  339. transformation is explicitly asked for by one of these options.

  340. </p>

  341. <p>For native builds, some of the installed programs are also installed

  342. with the target alias in front of their name, as in

  343. &lsquo;<samp>i686-pc-linux-gnu-gcc</samp>&rsquo;.  All of the above transformations happen

  344. before the target alias is prepended to the name&mdash;so, specifying

  345. <samp>--program-prefix=foo-</samp> and <samp>program-suffix=-3.1</samp>, the

  346. resulting binary would be installed as

  347. <samp>/usr/local/bin/i686-pc-linux-gnu-foo-gcc-3.1</samp>.

  348. </p>

  349. <p>As a last shortcoming, none of the installed Ada programs are

  350. transformed yet, which will be fixed in some time.

  351. </p>

  352. </dd>

  353. <dt><code>--with-local-prefix=<var>dirname</var></code></dt>

  354. <dd><p>Specify the

  355. installation directory for local include files.  The default is

  356. <samp>/usr/local</samp>.  Specify this option if you want the compiler to

  357. search directory <samp><var>dirname</var>/include</samp> for locally installed

  358. header files <em>instead</em> of <samp>/usr/local/include</samp>.

  359. </p>

  360. <p>You should specify <samp>--with-local-prefix</samp> <strong>only</strong> if your

  361. site has a different convention (not <samp>/usr/local</samp>) for where to put

  362. site-specific files.

  363. </p>

  364. <p>The default value for <samp>--with-local-prefix</samp> is <samp>/usr/local</samp>

  365. regardless of the value of <samp>--prefix</samp>.  Specifying

  366. <samp>--prefix</samp> has no effect on which directory GCC searches for

  367. local header files.  This may seem counterintuitive, but actually it is

  368. logical.

  369. </p>

  370. <p>The purpose of <samp>--prefix</samp> is to specify where to <em>install

  371. GCC</em>.  The local header files in <samp>/usr/local/include</samp>&mdash;if you put

  372. any in that directory&mdash;are not part of GCC.  They are part of other

  373. programs&mdash;perhaps many others.  (GCC installs its own header files in

  374. another directory which is based on the <samp>--prefix</samp> value.)

  375. </p>

  376. <p>Both the local-prefix include directory and the GCC-prefix include

  377. directory are part of GCC&rsquo;s &ldquo;system include&rdquo; directories.  Although these

  378. two directories are not fixed, they need to be searched in the proper

  379. order for the correct processing of the include_next directive.  The

  380. local-prefix include directory is searched before the GCC-prefix

  381. include directory.  Another characteristic of system include directories

  382. is that pedantic warnings are turned off for headers in these directories.

  383. </p>

  384. <p>Some autoconf macros add <samp>-I <var>directory</var></samp> options to the

  385. compiler command line, to ensure that directories containing installed

  386. packages&rsquo; headers are searched.  When <var>directory</var> is one of GCC&rsquo;s

  387. system include directories, GCC will ignore the option so that system

  388. directories continue to be processed in the correct order.  This

  389. may result in a search order different from what was specified but the

  390. directory will still be searched.

  391. </p>

  392. <p>GCC automatically searches for ordinary libraries using

  393. <code>GCC_EXEC_PREFIX</code>.  Thus, when the same installation prefix is

  394. used for both GCC and packages, GCC will automatically search for

  395. both headers and libraries.  This provides a configuration that is

  396. easy to use.  GCC behaves in a manner similar to that when it is

  397. installed as a system compiler in <samp>/usr</samp>.

  398. </p>

  399. <p>Sites that need to install multiple versions of GCC may not want to

  400. use the above simple configuration.  It is possible to use the

  401. <samp>--program-prefix</samp>, <samp>--program-suffix</samp> and

  402. <samp>--program-transform-name</samp> options to install multiple versions

  403. into a single directory, but it may be simpler to use different prefixes

  404. and the <samp>--with-local-prefix</samp> option to specify the location of the

  405. site-specific files for each version.  It will then be necessary for

  406. users to specify explicitly the location of local site libraries

  407. (e.g., with <code>LIBRARY_PATH</code>).

  408. </p>

  409. <p>The same value can be used for both <samp>--with-local-prefix</samp> and

  410. <samp>--prefix</samp> provided it is not <samp>/usr</samp>.  This can be used

  411. to avoid the default search of <samp>/usr/local/include</samp>.

  412. </p>

  413. <p><strong>Do not</strong> specify <samp>/usr</samp> as the <samp>--with-local-prefix</samp>!

  414. The directory you use for <samp>--with-local-prefix</samp> <strong>must not</strong>

  415. contain any of the system&rsquo;s standard header files.  If it did contain

  416. them, certain programs would be miscompiled (including GNU Emacs, on

  417. certain targets), because this would override and nullify the header

  418. file corrections made by the <code>fixincludes</code> script.

  419. </p>

  420. <p>Indications are that people who use this option use it based on mistaken

  421. ideas of what it is for.  People use it as if it specified where to

  422. install part of GCC.  Perhaps they make this assumption because

  423. installing GCC creates the directory.

  424. </p>

  425. </dd>

  426. <dt><code>--with-gcc-major-version-only</code></dt>

  427. <dd><p>Specifies that GCC should use only the major number rather than

  428. <var>major</var>.<var>minor</var>.<var>patchlevel</var> in filesystem paths.

  429. </p>

  430. </dd>

  431. <dt><code>--with-native-system-header-dir=<var>dirname</var></code></dt>

  432. <dd><p>Specifies that <var>dirname</var> is the directory that contains native system

  433. header files, rather than <samp>/usr/include</samp>.  This option is most useful

  434. if you are creating a compiler that should be isolated from the system

  435. as much as possible.  It is most commonly used with the

  436. <samp>--with-sysroot</samp> option and will cause GCC to search

  437. <var>dirname</var> inside the system root specified by that option.

  438. </p>

  439. </dd>

  440. <dt><code>--enable-shared[=<var>package</var>[,&hellip;]]</code></dt>

  441. <dd><p>Build shared versions of libraries, if shared libraries are supported on

  442. the target platform.  Unlike GCC 2.95.x and earlier, shared libraries

  443. are enabled by default on all platforms that support shared libraries.

  444. </p>

  445. <p>If a list of packages is given as an argument, build shared libraries

  446. only for the listed packages.  For other packages, only static libraries

  447. will be built.  Package names currently recognized in the GCC tree are

  448. &lsquo;<samp>libgcc</samp>&rsquo; (also known as &lsquo;<samp>gcc</samp>&rsquo;), &lsquo;<samp>libstdc++</samp>&rsquo; (not

  449. &lsquo;<samp>libstdc++-v3</samp>&rsquo;), &lsquo;<samp>libffi</samp>&rsquo;, &lsquo;<samp>zlib</samp>&rsquo;, &lsquo;<samp>boehm-gc</samp>&rsquo;,

  450. &lsquo;<samp>ada</samp>&rsquo;, &lsquo;<samp>libada</samp>&rsquo;, &lsquo;<samp>libgo</samp>&rsquo;, &lsquo;<samp>libobjc</samp>&rsquo;, and &lsquo;<samp>libphobos</samp>&rsquo;.

  451. Note &lsquo;<samp>libiberty</samp>&rsquo; does not support shared libraries at all.

  452. </p>

  453. <p>Use <samp>--disable-shared</samp> to build only static libraries.  Note that

  454. <samp>--disable-shared</samp> does not accept a list of package names as

  455. argument, only <samp>--enable-shared</samp> does.

  456. </p>

  457. <p>Contrast with <samp>--enable-host-shared</samp>, which affects <em>host</em>

  458. code.

  459. </p>

  460. </dd>

  461. <dt><code>--enable-host-shared</code></dt>

  462. <dd><p>Specify that the <em>host</em> code should be built into position-independent

  463. machine code (with -fPIC), allowing it to be used within shared libraries,

  464. but yielding a slightly slower compiler.

  465. </p>

  466. <p>This option is required when building the libgccjit.so library.

  467. </p>

  468. <p>Contrast with <samp>--enable-shared</samp>, which affects <em>target</em>

  469. libraries.

  470. </p>

  471. </dd>

  472. <dt><code><a name="with-gnu-as"></a>--with-gnu-as</code></dt>

  473. <dd><p>Specify that the compiler should assume that the

  474. assembler it finds is the GNU assembler.  However, this does not modify

  475. the rules to find an assembler and will result in confusion if the

  476. assembler found is not actually the GNU assembler.  (Confusion may also

  477. result if the compiler finds the GNU assembler but has not been

  478. configured with <samp>--with-gnu-as</samp>.)  If you have more than one

  479. assembler installed on your system, you may want to use this option in

  480. connection with <samp>--with-as=<var>pathname</var></samp> or

  481. <samp>--with-build-time-tools=<var>pathname</var></samp>.

  482. </p>

  483. <p>The following systems are the only ones where it makes a difference

  484. whether you use the GNU assembler.  On any other system,

  485. <samp>--with-gnu-as</samp> has no effect.

  486. </p>

  487. <ul>

  488. <li> &lsquo;<samp>hppa1.0-<var>any</var>-<var>any</var></samp>&rsquo;

  489. </li><li> &lsquo;<samp>hppa1.1-<var>any</var>-<var>any</var></samp>&rsquo;

  490. </li><li> &lsquo;<samp>sparc-sun-solaris2.<var>any</var></samp>&rsquo;

  491. </li><li> &lsquo;<samp>sparc64-<var>any</var>-solaris2.<var>any</var></samp>&rsquo;

  492. </li></ul>

  493. 

  494. </dd>

  495. <dt><code><a name="with-as"></a>--with-as=<var>pathname</var></code></dt>

  496. <dd><p>Specify that the compiler should use the assembler pointed to by

  497. <var>pathname</var>, rather than the one found by the standard rules to find

  498. an assembler, which are:

  499. </p><ul>

  500. <li> Unless GCC is being built with a cross compiler, check the

  501. <samp><var>libexec</var>/gcc/<var>target</var>/<var>version</var></samp> directory.

  502. <var>libexec</var> defaults to <samp><var>exec-prefix</var>/libexec</samp>;

  503. <var>exec-prefix</var> defaults to <var>prefix</var>, which

  504. defaults to <samp>/usr/local</samp> unless overridden by the

  505. <samp>--prefix=<var>pathname</var></samp> switch described above.  <var>target</var>

  506. is the target system triple, such as &lsquo;<samp>sparc-sun-solaris2.7</samp>&rsquo;, and

  507. <var>version</var> denotes the GCC version, such as 3.0.

  508. 

  509. </li><li> If the target system is the same that you are building on, check

  510. operating system specific directories (e.g. <samp>/usr/ccs/bin</samp> on

  511. Solaris 2).

  512. 

  513. </li><li> Check in the <code>PATH</code> for a tool whose name is prefixed by the

  514. target system triple.

  515. 

  516. </li><li> Check in the <code>PATH</code> for a tool whose name is not prefixed by the

  517. target system triple, if the host and target system triple are

  518. the same (in other words, we use a host tool if it can be used for

  519. the target as well).

  520. </li></ul>

  521. 

  522. <p>You may want to use <samp>--with-as</samp> if no assembler

  523. is installed in the directories listed above, or if you have multiple

  524. assemblers installed and want to choose one that is not found by the

  525. above rules.

  526. </p>

  527. </dd>

  528. <dt><code><a name="with-gnu-ld"></a>--with-gnu-ld</code></dt>

  529. <dd><p>Same as <a href="#with-gnu-as"><samp>--with-gnu-as</samp></a>

  530. but for the linker.

  531. </p>

  532. </dd>

  533. <dt><code>--with-ld=<var>pathname</var></code></dt>

  534. <dd><p>Same as <a href="#with-as"><samp>--with-as</samp></a>

  535. but for the linker.

  536. </p>

  537. </dd>

  538. <dt><code>--with-stabs</code></dt>

  539. <dd><p>Specify that stabs debugging

  540. information should be used instead of whatever format the host normally

  541. uses.  Normally GCC uses the same debug format as the host system.

  542. </p>

  543. </dd>

  544. <dt><code>--with-tls=<var>dialect</var></code></dt>

  545. <dd><p>Specify the default TLS dialect, for systems were there is a choice.

  546. For ARM targets, possible values for <var>dialect</var> are <code>gnu</code> or

  547. <code>gnu2</code>, which select between the original GNU dialect and the GNU TLS

  548. descriptor-based dialect.

  549. </p>

  550. </dd>

  551. <dt><code>--enable-multiarch</code></dt>

  552. <dd><p>Specify whether to enable or disable multiarch support.  The default is

  553. to check for glibc start files in a multiarch location, and enable it

  554. if the files are found.  The auto detection is enabled for native builds,

  555. and for cross builds configured with <samp>--with-sysroot</samp>, and without

  556. <samp>--with-native-system-header-dir</samp>.

  557. More documentation about multiarch can be found at

  558. <a href="https://wiki.debian.org/Multiarch">https://wiki.debian.org/Multiarch</a>.

  559. </p>

  560. </dd>

  561. <dt><code>--enable-sjlj-exceptions</code></dt>

  562. <dd><p>Force use of the <code>setjmp</code>/<code>longjmp</code>-based scheme for exceptions.

  563. &lsquo;<samp>configure</samp>&rsquo; ordinarily picks the correct value based on the platform.

  564. Only use this option if you are sure you need a different setting.

  565. </p>

  566. </dd>

  567. <dt><code>--enable-vtable-verify</code></dt>

  568. <dd><p>Specify whether to enable or disable the vtable verification feature.

  569. Enabling this feature causes libstdc++ to be built with its virtual calls

  570. in verifiable mode.  This means that, when linked with libvtv, every

  571. virtual call in libstdc++ will verify the vtable pointer through which the

  572. call will be made before actually making the call.  If not linked with libvtv,

  573. the verifier will call stub functions (in libstdc++ itself) and do nothing.

  574. If vtable verification is disabled, then libstdc++ is not built with its

  575. virtual calls in verifiable mode at all.  However the libvtv library will

  576. still be built (see <samp>--disable-libvtv</samp> to turn off building libvtv).

  577. <samp>--disable-vtable-verify</samp> is the default.

  578. </p>

  579. </dd>

  580. <dt><code>--disable-gcov</code></dt>

  581. <dd><p>Specify that the run-time library used for coverage analysis

  582. and associated host tools should not be built.

  583. </p>

  584. </dd>

  585. <dt><code>--disable-multilib</code></dt>

  586. <dd><p>Specify that multiple target

  587. libraries to support different target variants, calling

  588. conventions, etc. should not be built.  The default is to build a

  589. predefined set of them.

  590. </p>

  591. <p>Some targets provide finer-grained control over which multilibs are built

  592. (e.g., <samp>--disable-softfloat</samp>):

  593. </p><dl compact="compact">

  594. <dt><code>arm-*-*</code></dt>

  595. <dd><p>fpu, 26bit, underscore, interwork, biendian, nofmult.

  596. </p>

  597. </dd>

  598. <dt><code>m68*-*-*</code></dt>

  599. <dd><p>softfloat, m68881, m68000, m68020.

  600. </p>

  601. </dd>

  602. <dt><code>mips*-*-*</code></dt>

  603. <dd><p>single-float, biendian, softfloat.

  604. </p>

  605. </dd>

  606. <dt><code>msp430-*-*</code></dt>

  607. <dd><p>no-exceptions

  608. </p>

  609. </dd>

  610. <dt><code>powerpc*-*-*, rs6000*-*-*</code></dt>

  611. <dd><p>aix64, pthread, softfloat, powercpu, powerpccpu, powerpcos, biendian,

  612. sysv, aix.

  613. </p>

  614. </dd>

  615. </dl>

  616. 

  617. </dd>

  618. <dt><code>--with-multilib-list=<var>list</var></code></dt>

  619. <dt><code>--without-multilib-list</code></dt>

  620. <dd><p>Specify what multilibs to build.  <var>list</var> is a comma separated list of

  621. values, possibly consisting of a single value.  Currently only implemented

  622. for aarch64*-*-*, arm*-*-*, riscv*-*-*, sh*-*-* and x86-64-*-linux*.  The

  623. accepted values and meaning for each target is given below.

  624. </p>

  625. <dl compact="compact">

  626. <dt><code>aarch64*-*-*</code></dt>

  627. <dd><p><var>list</var> is a comma separated list of <code>ilp32</code>, and <code>lp64</code>

  628. to enable ILP32 and LP64 run-time libraries, respectively.  If

  629. <var>list</var> is empty, then there will be no multilibs and only the

  630. default run-time library will be built.  If <var>list</var> is

  631. <code>default</code> or &ndash;with-multilib-list= is not specified, then the

  632. default set of libraries is selected based on the value of

  633. <samp>--target</samp>.

  634. </p>

  635. </dd>

  636. <dt><code>arm*-*-*</code></dt>

  637. <dd><p><var>list</var> is a comma separated list of <code>aprofile</code> and

  638. <code>rmprofile</code> to build multilibs for A or R and M architecture

  639. profiles respectively.  Note that, due to some limitation of the current

  640. multilib framework, using the combined <code>aprofile,rmprofile</code>

  641. multilibs selects in some cases a less optimal multilib than when using

  642. the multilib profile for the architecture targetted.  The special value

  643. <code>default</code> is also accepted and is equivalent to omitting the

  644. option, i.e., only the default run-time library will be enabled.

  645. </p>

  646. <p><var>list</var> may instead contain <code>@name</code>, to use the multilib

  647. configuration Makefile fragment <samp>name</samp> in <samp>gcc/config/arm</samp> in

  648. the source tree (it is part of the corresponding sources, after all).

  649. It is recommended, but not required, that files used for this purpose to

  650. be named starting with <samp>t-ml-</samp>, to make their intended purpose

  651. self-evident, in line with GCC conventions.  Such files enable custom,

  652. user-chosen multilib lists to be configured.  Whether multiple such

  653. files can be used together depends on the contents of the supplied

  654. files.  See <samp>gcc/config/arm/t-multilib</samp> and its supplementary

  655. <samp>gcc/config/arm/t-*profile</samp> files for an example of what such

  656. Makefile fragments might look like for this version of GCC.  The macros

  657. expected to be defined in these fragments are not stable across GCC

  658. releases, so make sure they define the <code>MULTILIB</code>-related macros

  659. expected by the version of GCC you are building.

  660. See &ldquo;Target Makefile Fragments&rdquo; in the internals manual.

  661. </p>

  662. <p>The table below gives the combination of ISAs, architectures, FPUs and

  663. floating-point ABIs for which multilibs are built for each predefined

  664. profile.  The union of these options is considered when specifying both

  665. <code>aprofile</code> and <code>rmprofile</code>.

  666. </p>

  667. <table>

  668. <tr><td width="15%">Option</td><td width="28%">aprofile</td><td width="30%">rmprofile</td></tr>

  669. <tr><td width="15%">ISAs</td><td width="28%"><code>-marm</code> and <code>-mthumb</code></td><td width="30%"><code>-mthumb</code></td></tr>

  670. <tr><td width="15%">Architectures<br><br><br><br><br><br></td><td width="28%">default architecture<br>

  671. <code>-march=armv7-a</code><br>

  672. <code>-march=armv7ve</code><br>

  673. <code>-march=armv8-a</code><br><br><br></td><td width="30%">default architecture<br>

  674. <code>-march=armv6s-m</code><br>

  675. <code>-march=armv7-m</code><br>

  676. <code>-march=armv7e-m</code><br>

  677. <code>-march=armv8-m.base</code><br>

  678. <code>-march=armv8-m.main</code><br>

  679. <code>-march=armv7</code></td></tr>

  680. <tr><td width="15%">FPUs<br><br><br><br><br></td><td width="28%">none<br>

  681. <code>-mfpu=vfpv3-d16</code><br>

  682. <code>-mfpu=neon</code><br>

  683. <code>-mfpu=vfpv4-d16</code><br>

  684. <code>-mfpu=neon-vfpv4</code><br>

  685. <code>-mfpu=neon-fp-armv8</code></td><td width="30%">none<br>

  686. <code>-mfpu=vfpv3-d16</code><br>

  687. <code>-mfpu=fpv4-sp-d16</code><br>

  688. <code>-mfpu=fpv5-sp-d16</code><br>

  689. <code>-mfpu=fpv5-d16</code><br></td></tr>

  690. <tr><td width="15%">floating-point ABIs<br><br></td><td width="28%"><code>-mfloat-abi=soft</code><br>

  691. <code>-mfloat-abi=softfp</code><br>

  692. <code>-mfloat-abi=hard</code></td><td width="30%"><code>-mfloat-abi=soft</code><br>

  693. <code>-mfloat-abi=softfp</code><br>

  694. <code>-mfloat-abi=hard</code></td></tr>

  695. </table>

  696. 

  697. </dd>

  698. <dt><code>riscv*-*-*</code></dt>

  699. <dd><p><var>list</var> is a single ABI name.  The target architecture must be either

  700. <code>rv32gc</code> or <code>rv64gc</code>.  This will build a single multilib for the

  701. specified architecture and ABI pair.  If <code>--with-multilib-list</code> is not

  702. given, then a default set of multilibs is selected based on the value of

  703. <samp>--target</samp>.  This is usually a large set of multilibs.

  704. </p>

  705. </dd>

  706. <dt><code>sh*-*-*</code></dt>

  707. <dd><p><var>list</var> is a comma separated list of CPU names.  These must be of the

  708. form <code>sh*</code> or <code>m*</code> (in which case they match the compiler option

  709. for that processor).  The list should not contain any endian options -

  710. these are handled by <samp>--with-endian</samp>.

  711. </p>

  712. <p>If <var>list</var> is empty, then there will be no multilibs for extra

  713. processors.  The multilib for the secondary endian remains enabled.

  714. </p>

  715. <p>As a special case, if an entry in the list starts with a <code>!</code>

  716. (exclamation point), then it is added to the list of excluded multilibs.

  717. Entries of this sort should be compatible with &lsquo;<samp>MULTILIB_EXCLUDES</samp>&rsquo;

  718. (once the leading <code>!</code> has been stripped).

  719. </p>

  720. <p>If <samp>--with-multilib-list</samp> is not given, then a default set of

  721. multilibs is selected based on the value of <samp>--target</samp>.  This is

  722. usually the complete set of libraries, but some targets imply a more

  723. specialized subset.

  724. </p>

  725. <p>Example 1: to configure a compiler for SH4A only, but supporting both

  726. endians, with little endian being the default:

  727. </p><div class="smallexample">

  728. <pre class="smallexample">--with-cpu=sh4a --with-endian=little,big --with-multilib-list=

  729. </pre></div>

  730. 

  731. <p>Example 2: to configure a compiler for both SH4A and SH4AL-DSP, but with

  732. only little endian SH4AL:

  733. </p><div class="smallexample">

  734. <pre class="smallexample">--with-cpu=sh4a --with-endian=little,big \

  735. --with-multilib-list=sh4al,!mb/m4al

  736. </pre></div>

  737. 

  738. </dd>

  739. <dt><code>x86-64-*-linux*</code></dt>

  740. <dd><p><var>list</var> is a comma separated list of <code>m32</code>, <code>m64</code> and

  741. <code>mx32</code> to enable 32-bit, 64-bit and x32 run-time libraries,

  742. respectively.  If <var>list</var> is empty, then there will be no multilibs

  743. and only the default run-time library will be enabled.

  744. </p>

  745. <p>If <samp>--with-multilib-list</samp> is not given, then only 32-bit and

  746. 64-bit run-time libraries will be enabled.

  747. </p></dd>

  748. </dl>

  749. 

  750. </dd>

  751. <dt><code>--with-endian=<var>endians</var></code></dt>

  752. <dd><p>Specify what endians to use.

  753. Currently only implemented for sh*-*-*.

  754. </p>

  755. <p><var>endians</var> may be one of the following:

  756. </p><dl compact="compact">

  757. <dt><code>big</code></dt>

  758. <dd><p>Use big endian exclusively.

  759. </p></dd>

  760. <dt><code>little</code></dt>

  761. <dd><p>Use little endian exclusively.

  762. </p></dd>

  763. <dt><code>big,little</code></dt>

  764. <dd><p>Use big endian by default.  Provide a multilib for little endian.

  765. </p></dd>

  766. <dt><code>little,big</code></dt>

  767. <dd><p>Use little endian by default.  Provide a multilib for big endian.

  768. </p></dd>

  769. </dl>

  770. 

  771. </dd>

  772. <dt><code>--enable-threads</code></dt>

  773. <dd><p>Specify that the target

  774. supports threads.  This affects the Objective-C compiler and runtime

  775. library, and exception handling for other languages like C++.

  776. On some systems, this is the default.

  777. </p>

  778. <p>In general, the best (and, in many cases, the only known) threading

  779. model available will be configured for use.  Beware that on some

  780. systems, GCC has not been taught what threading models are generally

  781. available for the system.  In this case, <samp>--enable-threads</samp> is an

  782. alias for <samp>--enable-threads=single</samp>.

  783. </p>

  784. </dd>

  785. <dt><code>--disable-threads</code></dt>

  786. <dd><p>Specify that threading support should be disabled for the system.

  787. This is an alias for <samp>--enable-threads=single</samp>.

  788. </p>

  789. </dd>

  790. <dt><code>--enable-threads=<var>lib</var></code></dt>

  791. <dd><p>Specify that

  792. <var>lib</var> is the thread support library.  This affects the Objective-C

  793. compiler and runtime library, and exception handling for other languages

  794. like C++.  The possibilities for <var>lib</var> are:

  795. </p>

  796. <dl compact="compact">

  797. <dt><code>aix</code></dt>

  798. <dd><p>AIX thread support.

  799. </p></dd>

  800. <dt><code>dce</code></dt>

  801. <dd><p>DCE thread support.

  802. </p></dd>

  803. <dt><code>lynx</code></dt>

  804. <dd><p>LynxOS thread support.

  805. </p></dd>

  806. <dt><code>mipssde</code></dt>

  807. <dd><p>MIPS SDE thread support.

  808. </p></dd>

  809. <dt><code>no</code></dt>

  810. <dd><p>This is an alias for &lsquo;<samp>single</samp>&rsquo;.

  811. </p></dd>

  812. <dt><code>posix</code></dt>

  813. <dd><p>Generic POSIX/Unix98 thread support.

  814. </p></dd>

  815. <dt><code>rtems</code></dt>

  816. <dd><p>RTEMS thread support.

  817. </p></dd>

  818. <dt><code>single</code></dt>

  819. <dd><p>Disable thread support, should work for all platforms.

  820. </p></dd>

  821. <dt><code>tpf</code></dt>

  822. <dd><p>TPF thread support.

  823. </p></dd>

  824. <dt><code>vxworks</code></dt>

  825. <dd><p>VxWorks thread support.

  826. </p></dd>

  827. <dt><code>win32</code></dt>

  828. <dd><p>Microsoft Win32 API thread support.

  829. </p></dd>

  830. </dl>

  831. 

  832. </dd>

  833. <dt><code>--enable-tls</code></dt>

  834. <dd><p>Specify that the target supports TLS (Thread Local Storage).  Usually

  835. configure can correctly determine if TLS is supported.  In cases where

  836. it guesses incorrectly, TLS can be explicitly enabled or disabled with

  837. <samp>--enable-tls</samp> or <samp>--disable-tls</samp>.  This can happen if

  838. the assembler supports TLS but the C library does not, or if the

  839. assumptions made by the configure test are incorrect.

  840. </p>

  841. </dd>

  842. <dt><code>--disable-tls</code></dt>

  843. <dd><p>Specify that the target does not support TLS.

  844. This is an alias for <samp>--enable-tls=no</samp>.

  845. </p>

  846. </dd>

  847. <dt><code>--disable-tm-clone-registry</code></dt>

  848. <dd><p>Disable TM clone registry in libgcc. It is enabled in libgcc by default.

  849. This option helps to reduce code size for embedded targets which do

  850. not use transactional memory.

  851. </p>

  852. </dd>

  853. <dt><code>--with-cpu=<var>cpu</var></code></dt>

  854. <dt><code>--with-cpu-32=<var>cpu</var></code></dt>

  855. <dt><code>--with-cpu-64=<var>cpu</var></code></dt>

  856. <dd><p>Specify which cpu variant the compiler should generate code for by default.

  857. <var>cpu</var> will be used as the default value of the <samp>-mcpu=</samp> switch.

  858. This option is only supported on some targets, including ARC, ARM, i386, M68k,

  859. PowerPC, and SPARC.  It is mandatory for ARC.  The <samp>--with-cpu-32</samp> and

  860. <samp>--with-cpu-64</samp> options specify separate default CPUs for

  861. 32-bit and 64-bit modes; these options are only supported for i386,

  862. x86-64, PowerPC, and SPARC.

  863. </p>

  864. </dd>

  865. <dt><code>--with-schedule=<var>cpu</var></code></dt>

  866. <dt><code>--with-arch=<var>cpu</var></code></dt>

  867. <dt><code>--with-arch-32=<var>cpu</var></code></dt>

  868. <dt><code>--with-arch-64=<var>cpu</var></code></dt>

  869. <dt><code>--with-tune=<var>cpu</var></code></dt>

  870. <dt><code>--with-tune-32=<var>cpu</var></code></dt>

  871. <dt><code>--with-tune-64=<var>cpu</var></code></dt>

  872. <dt><code>--with-abi=<var>abi</var></code></dt>

  873. <dt><code>--with-fpu=<var>type</var></code></dt>

  874. <dt><code>--with-float=<var>type</var></code></dt>

  875. <dd><p>These configure options provide default values for the <samp>-mschedule=</samp>,

  876. <samp>-march=</samp>, <samp>-mtune=</samp>, <samp>-mabi=</samp>, and <samp>-mfpu=</samp>

  877. options and for <samp>-mhard-float</samp> or <samp>-msoft-float</samp>.  As with

  878. <samp>--with-cpu</samp>, which switches will be accepted and acceptable values

  879. of the arguments depend on the target.

  880. </p>

  881. </dd>

  882. <dt><code>--with-mode=<var>mode</var></code></dt>

  883. <dd><p>Specify if the compiler should default to <samp>-marm</samp> or <samp>-mthumb</samp>.

  884. This option is only supported on ARM targets.

  885. </p>

  886. </dd>

  887. <dt><code>--with-stack-offset=<var>num</var></code></dt>

  888. <dd><p>This option sets the default for the -mstack-offset=<var>num</var> option,

  889. and will thus generally also control the setting of this option for

  890. libraries.  This option is only supported on Epiphany targets.

  891. </p>

  892. </dd>

  893. <dt><code>--with-fpmath=<var>isa</var></code></dt>

  894. <dd><p>This options sets <samp>-mfpmath=sse</samp> by default and specifies the default

  895. ISA for floating-point arithmetics.  You can select either &lsquo;<samp>sse</samp>&rsquo; which

  896. enables <samp>-msse2</samp> or &lsquo;<samp>avx</samp>&rsquo; which enables <samp>-mavx</samp> by default.

  897. This option is only supported on i386 and x86-64 targets.

  898. </p>

  899. </dd>

  900. <dt><code>--with-fp-32=<var>mode</var></code></dt>

  901. <dd><p>On MIPS targets, set the default value for the <samp>-mfp</samp> option when using

  902. the o32 ABI.  The possibilities for <var>mode</var> are:

  903. </p><dl compact="compact">

  904. <dt><code>32</code></dt>

  905. <dd><p>Use the o32 FP32 ABI extension, as with the <samp>-mfp32</samp> command-line

  906. option.

  907. </p></dd>

  908. <dt><code>xx</code></dt>

  909. <dd><p>Use the o32 FPXX ABI extension, as with the <samp>-mfpxx</samp> command-line

  910. option.

  911. </p></dd>

  912. <dt><code>64</code></dt>

  913. <dd><p>Use the o32 FP64 ABI extension, as with the <samp>-mfp64</samp> command-line

  914. option.

  915. </p></dd>

  916. </dl>

  917. <p>In the absence of this configuration option the default is to use the o32

  918. FP32 ABI extension.

  919. </p>

  920. </dd>

  921. <dt><code>--with-odd-spreg-32</code></dt>

  922. <dd><p>On MIPS targets, set the <samp>-modd-spreg</samp> option by default when using

  923. the o32 ABI.

  924. </p>

  925. </dd>

  926. <dt><code>--without-odd-spreg-32</code></dt>

  927. <dd><p>On MIPS targets, set the <samp>-mno-odd-spreg</samp> option by default when using

  928. the o32 ABI.  This is normally used in conjunction with

  929. <samp>--with-fp-32=64</samp> in order to target the o32 FP64A ABI extension.

  930. </p>

  931. </dd>

  932. <dt><code>--with-nan=<var>encoding</var></code></dt>

  933. <dd><p>On MIPS targets, set the default encoding convention to use for the

  934. special not-a-number (NaN) IEEE 754 floating-point data.  The

  935. possibilities for <var>encoding</var> are:

  936. </p><dl compact="compact">

  937. <dt><code>legacy</code></dt>

  938. <dd><p>Use the legacy encoding, as with the <samp>-mnan=legacy</samp> command-line

  939. option.

  940. </p></dd>

  941. <dt><code>2008</code></dt>

  942. <dd><p>Use the 754-2008 encoding, as with the <samp>-mnan=2008</samp> command-line

  943. option.

  944. </p></dd>

  945. </dl>

  946. <p>To use this configuration option you must have an assembler version

  947. installed that supports the <samp>-mnan=</samp> command-line option too.

  948. In the absence of this configuration option the default convention is

  949. the legacy encoding, as when neither of the <samp>-mnan=2008</samp> and

  950. <samp>-mnan=legacy</samp> command-line options has been used.

  951. </p>

  952. </dd>

  953. <dt><code>--with-divide=<var>type</var></code></dt>

  954. <dd><p>Specify how the compiler should generate code for checking for

  955. division by zero.  This option is only supported on the MIPS target.

  956. The possibilities for <var>type</var> are:

  957. </p><dl compact="compact">

  958. <dt><code>traps</code></dt>

  959. <dd><p>Division by zero checks use conditional traps (this is the default on

  960. systems that support conditional traps).

  961. </p></dd>

  962. <dt><code>breaks</code></dt>

  963. <dd><p>Division by zero checks use the break instruction.

  964. </p></dd>

  965. </dl>

  966. 

  967. 

  968. </dd>

  969. <dt><code>--with-llsc</code></dt>

  970. <dd><p>On MIPS targets, make <samp>-mllsc</samp> the default when no

  971. <samp>-mno-llsc</samp> option is passed.  This is the default for

  972. Linux-based targets, as the kernel will emulate them if the ISA does

  973. not provide them.

  974. </p>

  975. </dd>

  976. <dt><code>--without-llsc</code></dt>

  977. <dd><p>On MIPS targets, make <samp>-mno-llsc</samp> the default when no

  978. <samp>-mllsc</samp> option is passed.

  979. </p>

  980. </dd>

  981. <dt><code>--with-synci</code></dt>

  982. <dd><p>On MIPS targets, make <samp>-msynci</samp> the default when no

  983. <samp>-mno-synci</samp> option is passed.

  984. </p>

  985. </dd>

  986. <dt><code>--without-synci</code></dt>

  987. <dd><p>On MIPS targets, make <samp>-mno-synci</samp> the default when no

  988. <samp>-msynci</samp> option is passed.  This is the default.

  989. </p>

  990. </dd>

  991. <dt><code>--with-lxc1-sxc1</code></dt>

  992. <dd><p>On MIPS targets, make <samp>-mlxc1-sxc1</samp> the default when no

  993. <samp>-mno-lxc1-sxc1</samp> option is passed.  This is the default.

  994. </p>

  995. </dd>

  996. <dt><code>--without-lxc1-sxc1</code></dt>

  997. <dd><p>On MIPS targets, make <samp>-mno-lxc1-sxc1</samp> the default when no

  998. <samp>-mlxc1-sxc1</samp> option is passed.  The indexed load/store

  999. instructions are not directly a problem but can lead to unexpected

  1000. behaviour when deployed in an application intended for a 32-bit address

  1001. space but run on a 64-bit processor.  The issue is seen because all

  1002. known MIPS 64-bit Linux kernels execute o32 and n32 applications

  1003. with 64-bit addressing enabled which affects the overflow behaviour

  1004. of the indexed addressing mode.  GCC will assume that ordinary

  1005. 32-bit arithmetic overflow behaviour is the same whether performed

  1006. as an <code>addu</code> instruction or as part of the address calculation

  1007. in <code>lwxc1</code> type instructions.  This assumption holds true in a

  1008. pure 32-bit environment and can hold true in a 64-bit environment if

  1009. the address space is accurately set to be 32-bit for o32 and n32.

  1010. </p>

  1011. </dd>

  1012. <dt><code>--with-madd4</code></dt>

  1013. <dd><p>On MIPS targets, make <samp>-mmadd4</samp> the default when no

  1014. <samp>-mno-madd4</samp> option is passed.  This is the default.

  1015. </p>

  1016. </dd>

  1017. <dt><code>--without-madd4</code></dt>

  1018. <dd><p>On MIPS targets, make <samp>-mno-madd4</samp> the default when no

  1019. <samp>-mmadd4</samp> option is passed.  The <code>madd4</code> instruction

  1020. family can be problematic when targeting a combination of cores that

  1021. implement these instructions differently.  There are two known cores

  1022. that implement these as fused operations instead of unfused (where

  1023. unfused is normally expected).  Disabling these instructions is the

  1024. only way to ensure compatible code is generated; this will incur

  1025. a performance penalty.

  1026. </p>

  1027. </dd>

  1028. <dt><code>--with-mips-plt</code></dt>

  1029. <dd><p>On MIPS targets, make use of copy relocations and PLTs.

  1030. These features are extensions to the traditional

  1031. SVR4-based MIPS ABIs and require support from GNU binutils

  1032. and the runtime C library.

  1033. </p>

  1034. </dd>

  1035. <dt><code>--with-stack-clash-protection-guard-size=<var>size</var></code></dt>

  1036. <dd><p>On certain targets this option sets the default stack clash protection guard

  1037. size as a power of two in bytes.  On AArch64 <var>size</var> is required to be either

  1038. 12 (4KB) or 16 (64KB).

  1039. </p>

  1040. </dd>

  1041. <dt><code>--enable-__cxa_atexit</code></dt>

  1042. <dd><p>Define if you want to use __cxa_atexit, rather than atexit, to

  1043. register C++ destructors for local statics and global objects.

  1044. This is essential for fully standards-compliant handling of

  1045. destructors, but requires __cxa_atexit in libc.  This option is currently

  1046. only available on systems with GNU libc.  When enabled, this will cause

  1047. <samp>-fuse-cxa-atexit</samp> to be passed by default.

  1048. </p>

  1049. </dd>

  1050. <dt><code>--enable-gnu-indirect-function</code></dt>

  1051. <dd><p>Define if you want to enable the <code>ifunc</code> attribute.  This option is

  1052. currently only available on systems with GNU libc on certain targets.

  1053. </p>

  1054. </dd>

  1055. <dt><code>--enable-target-optspace</code></dt>

  1056. <dd><p>Specify that target

  1057. libraries should be optimized for code space instead of code speed.

  1058. This is the default for the m32r platform.

  1059. </p>

  1060. </dd>

  1061. <dt><code>--with-cpp-install-dir=<var>dirname</var></code></dt>

  1062. <dd><p>Specify that the user visible <code>cpp</code> program should be installed

  1063. in <samp><var>prefix</var>/<var>dirname</var>/cpp</samp>, in addition to <var>bindir</var>.

  1064. </p>

  1065. </dd>

  1066. <dt><code>--enable-comdat</code></dt>

  1067. <dd><p>Enable COMDAT group support.  This is primarily used to override the

  1068. automatically detected value.

  1069. </p>

  1070. </dd>

  1071. <dt><code>--enable-initfini-array</code></dt>

  1072. <dd><p>Force the use of sections <code>.init_array</code> and <code>.fini_array</code>

  1073. (instead of <code>.init</code> and <code>.fini</code>) for constructors and

  1074. destructors.  Option <samp>--disable-initfini-array</samp> has the

  1075. opposite effect.  If neither option is specified, the configure script

  1076. will try to guess whether the <code>.init_array</code> and

  1077. <code>.fini_array</code> sections are supported and, if they are, use them.

  1078. </p>

  1079. </dd>

  1080. <dt><code>--enable-link-mutex</code></dt>

  1081. <dd><p>When building GCC, use a mutex to avoid linking the compilers for

  1082. multiple languages at the same time, to avoid thrashing on build

  1083. systems with limited free memory.  The default is not to use such a mutex.

  1084. </p>

  1085. </dd>

  1086. <dt><code>--enable-maintainer-mode</code></dt>

  1087. <dd><p>The build rules that regenerate the Autoconf and Automake output files as

  1088. well as the GCC master message catalog <samp>gcc.pot</samp> are normally

  1089. disabled.  This is because it can only be rebuilt if the complete source

  1090. tree is present.  If you have changed the sources and want to rebuild the

  1091. catalog, configuring with <samp>--enable-maintainer-mode</samp> will enable

  1092. this.  Note that you need a recent version of the <code>gettext</code> tools

  1093. to do so.

  1094. </p>

  1095. </dd>

  1096. <dt><code>--disable-bootstrap</code></dt>

  1097. <dd><p>For a native build, the default configuration is to perform

  1098. a 3-stage bootstrap of the compiler when &lsquo;<samp>make</samp>&rsquo; is invoked,

  1099. testing that GCC can compile itself correctly.  If you want to disable

  1100. this process, you can configure with <samp>--disable-bootstrap</samp>.

  1101. </p>

  1102. </dd>

  1103. <dt><code>--enable-bootstrap</code></dt>

  1104. <dd><p>In special cases, you may want to perform a 3-stage build

  1105. even if the target and host triplets are different.

  1106. This is possible when the host can run code compiled for

  1107. the target (e.g. host is i686-linux, target is i486-linux).

  1108. Starting from GCC 4.2, to do this you have to configure explicitly

  1109. with <samp>--enable-bootstrap</samp>.

  1110. </p>

  1111. </dd>

  1112. <dt><code>--enable-generated-files-in-srcdir</code></dt>

  1113. <dd><p>Neither the .c and .h files that are generated from Bison and flex nor the

  1114. info manuals and man pages that are built from the .texi files are present

  1115. in the repository development tree.  When building GCC from that development tree,

  1116. or from one of our snapshots, those generated files are placed in your

  1117. build directory, which allows for the source to be in a readonly

  1118. directory.

  1119. </p>

  1120. <p>If you configure with <samp>--enable-generated-files-in-srcdir</samp> then those

  1121. generated files will go into the source directory.  This is mainly intended

  1122. for generating release or prerelease tarballs of the GCC sources, since it

  1123. is not a requirement that the users of source releases to have flex, Bison,

  1124. or makeinfo.

  1125. </p>

  1126. </dd>

  1127. <dt><code>--enable-version-specific-runtime-libs</code></dt>

  1128. <dd><p>Specify

  1129. that runtime libraries should be installed in the compiler specific

  1130. subdirectory (<samp><var>libdir</var>/gcc</samp>) rather than the usual places.  In

  1131. addition, &lsquo;<samp>libstdc++</samp>&rsquo;&rsquo;s include files will be installed into

  1132. <samp><var>libdir</var></samp> unless you overruled it by using

  1133. <samp>--with-gxx-include-dir=<var>dirname</var></samp>.  Using this option is

  1134. particularly useful if you intend to use several versions of GCC in

  1135. parallel.  The default is &lsquo;<samp>yes</samp>&rsquo; for &lsquo;<samp>libada</samp>&rsquo;, and &lsquo;<samp>no</samp>&rsquo; for

  1136. the remaining libraries.

  1137. </p>

  1138. </dd>

  1139. <dt><code><a name="WithAixSoname"></a>--with-aix-soname=&lsquo;<samp>aix</samp>&rsquo;, &lsquo;<samp>svr4</samp>&rsquo; or &lsquo;<samp>both</samp>&rsquo;</code></dt>

  1140. <dd><p>Traditional AIX shared library versioning (versioned <code>Shared Object</code>

  1141. files as members of unversioned <code>Archive Library</code> files named

  1142. &lsquo;<samp>lib.a</samp>&rsquo;) causes numerous headaches for package managers. However,

  1143. <code>Import Files</code> as members of <code>Archive Library</code> files allow for

  1144. <strong>filename-based versioning</strong> of shared libraries as seen on Linux/SVR4,

  1145. where this is called the &quot;SONAME&quot;. But as they prevent static linking,

  1146. <code>Import Files</code> may be used with <code>Runtime Linking</code> only, where the

  1147. linker does search for &lsquo;<samp>libNAME.so</samp>&rsquo; before &lsquo;<samp>libNAME.a</samp>&rsquo; library

  1148. filenames with the &lsquo;<samp>-lNAME</samp>&rsquo; linker flag.

  1149. </p>

  1150. <a name="AixLdCommand"></a><p>For detailed information please refer to the AIX

  1151. <a href="https://www.ibm.com/support/knowledgecenter/search/%22the%20ld%20command%2C%20also%20called%20the%20linkage%20editor%20or%20binder%22">ld

  1152. Command</a> reference.

  1153. </p>

  1154. <p>As long as shared library creation is enabled, upon:

  1155. </p><dl compact="compact">

  1156. <dt><code>--with-aix-soname=aix</code></dt>

  1157. <dt><code>--with-aix-soname=both</code></dt>

  1158. <dd><p>A (traditional AIX) <code>Shared Archive Library</code> file is created:

  1159.  </p><ul>

  1160. <li> using the &lsquo;<samp>libNAME.a</samp>&rsquo; filename scheme

  1161.   </li><li> with the <code>Shared Object</code> file as archive member named

  1162.   &lsquo;<samp>libNAME.so.V</samp>&rsquo; (except for &lsquo;<samp>libgcc_s</samp>&rsquo;, where the <code>Shared

  1163.   Object</code> file is named &lsquo;<samp>shr.o</samp>&rsquo; for backwards compatibility), which

  1164.   <ul class="no-bullet">

  1165. <li>- is used for runtime loading from inside the &lsquo;<samp>libNAME.a</samp>&rsquo; file

  1166.    </li><li>- is used for dynamic loading via

  1167.    <code>dlopen(&quot;libNAME.a(libNAME.so.V)&quot;, RTLD_MEMBER)</code>

  1168.    </li><li>- is used for shared linking

  1169.    </li><li>- is used for static linking, so no separate <code>Static Archive

  1170.    Library</code> file is needed

  1171.   </li></ul>

  1172. </li></ul>

  1173. </dd>

  1174. <dt><code>--with-aix-soname=both</code></dt>

  1175. <dt><code>--with-aix-soname=svr4</code></dt>

  1176. <dd><p>A (second) <code>Shared Archive Library</code> file is created:

  1177.  </p><ul>

  1178. <li> using the &lsquo;<samp>libNAME.so.V</samp>&rsquo; filename scheme

  1179.  </li><li> with the <code>Shared Object</code> file as archive member named

  1180.  &lsquo;<samp>shr.o</samp>&rsquo;, which

  1181.   <ul class="no-bullet">

  1182. <li>- is created with the <code>-G linker flag</code>

  1183.    </li><li>- has the <code>F_LOADONLY</code> flag set

  1184.    </li><li>- is used for runtime loading from inside the &lsquo;<samp>libNAME.so.V</samp>&rsquo; file

  1185.    </li><li>- is used for dynamic loading via <code>dlopen(&quot;libNAME.so.V(shr.o)&quot;,

  1186.    RTLD_MEMBER)</code>

  1187.   </li></ul>

  1188. </li><li> with the <code>Import File</code> as archive member named &lsquo;<samp>shr.imp</samp>&rsquo;,

  1189.  which

  1190.   <ul class="no-bullet">

  1191. <li>- refers to &lsquo;<samp>libNAME.so.V(shr.o)</samp>&rsquo; as the &quot;SONAME&quot;, to be recorded

  1192.    in the <code>Loader Section</code> of subsequent binaries

  1193.    </li><li>- indicates whether &lsquo;<samp>libNAME.so.V(shr.o)</samp>&rsquo; is 32 or 64 bit

  1194.    </li><li>- lists all the public symbols exported by &lsquo;<samp>lib.so.V(shr.o)</samp>&rsquo;,

  1195.    eventually decorated with the <code>&lsquo;<samp>weak</samp>&rsquo; Keyword</code>

  1196.    </li><li>- is necessary for shared linking against &lsquo;<samp>lib.so.V(shr.o)</samp>&rsquo;

  1197.    </li></ul>

  1198. </li></ul>

  1199. <p>A symbolic link using the &lsquo;<samp>libNAME.so</samp>&rsquo; filename scheme is created:

  1200.   </p><ul>

  1201. <li> pointing to the &lsquo;<samp>libNAME.so.V</samp>&rsquo; <code>Shared Archive Library</code> file

  1202.   </li><li> to permit the <code>ld Command</code> to find &lsquo;<samp>lib.so.V(shr.imp)</samp>&rsquo; via

  1203.   the &lsquo;<samp>-lNAME</samp>&rsquo; argument (requires <code>Runtime Linking</code> to be enabled)

  1204.   </li><li> to permit dynamic loading of &lsquo;<samp>lib.so.V(shr.o)</samp>&rsquo; without the need

  1205.   to specify the version number via <code>dlopen(&quot;libNAME.so(shr.o)&quot;,

  1206.   RTLD_MEMBER)</code>

  1207.   </li></ul>

  1208. </dd>

  1209. </dl>

  1210. 

  1211. <p>As long as static library creation is enabled, upon:

  1212. </p><dl compact="compact">

  1213. <dt><code>--with-aix-soname=svr4</code></dt>

  1214. <dd><p>A <code>Static Archive Library</code> is created:

  1215.  </p><ul>

  1216. <li> using the &lsquo;<samp>libNAME.a</samp>&rsquo; filename scheme

  1217.  </li><li> with all the <code>Static Object</code> files as archive members, which

  1218.   <ul class="no-bullet">

  1219. <li>- are used for static linking

  1220.   </li></ul>

  1221. </li></ul>

  1222. </dd>

  1223. </dl>

  1224. 

  1225. <p>While the aix-soname=&lsquo;<samp>svr4</samp>&rsquo; option does not create <code>Shared Object</code>

  1226. files as members of unversioned <code>Archive Library</code> files any more, package

  1227. managers still are responsible to

  1228. <a href="./specific.html#TransferAixShobj">transfer</a> <code>Shared Object</code> files

  1229. found as member of a previously installed unversioned <code>Archive Library</code>

  1230. file into the newly installed <code>Archive Library</code> file with the same

  1231. filename.

  1232. </p>

  1233. <p><em>WARNING:</em> Creating <code>Shared Object</code> files with <code>Runtime Linking</code>

  1234. enabled may bloat the TOC, eventually leading to <code>TOC overflow</code> errors,

  1235. requiring the use of either the <samp>-Wl,-bbigtoc</samp> linker flag (seen to

  1236. break with the <code>GDB</code> debugger) or some of the TOC-related compiler flags,

  1237. see &ldquo;RS/6000 and PowerPC Options&rdquo; in the main manual.

  1238. </p>

  1239. <p><samp>--with-aix-soname</samp> is currently supported by &lsquo;<samp>libgcc_s</samp>&rsquo; only, so

  1240. this option is still experimental and not for normal use yet.

  1241. </p>

  1242. <p>Default is the traditional behavior <samp>--with-aix-soname=&lsquo;<samp>aix</samp>&rsquo;</samp>.

  1243. </p>

  1244. </dd>

  1245. <dt><code>--enable-languages=<var>lang1</var>,<var>lang2</var>,&hellip;</code></dt>

  1246. <dd><p>Specify that only a particular subset of compilers and

  1247. their runtime libraries should be built.  For a list of valid values for

  1248. <var>langN</var> you can issue the following command in the

  1249. <samp>gcc</samp> directory of your GCC source tree:<br>

  1250. </p><div class="smallexample">

  1251. <pre class="smallexample">grep ^language= */config-lang.in

  1252. </pre></div>

  1253. <p>Currently, you can use any of the following:

  1254. <code>all</code>, <code>default</code>, <code>ada</code>, <code>c</code>, <code>c++</code>, <code>d</code>,

  1255. <code>fortran</code>, <code>go</code>, <code>jit</code>, <code>lto</code>, <code>objc</code>, <code>obj-c++</code>.

  1256. Building the Ada compiler has special requirements, see below.

  1257. If you do not pass this flag, or specify the option <code>default</code>, then the

  1258. default languages available in the <samp>gcc</samp> sub-tree will be configured.

  1259. Ada, D, Go, Jit, and Objective-C++ are not default languages.  LTO is not a

  1260. default language, but is built by default because <samp>--enable-lto</samp> is

  1261. enabled by default.  The other languages are default languages.  If

  1262. <code>all</code> is specified, then all available languages are built.  An

  1263. exception is <code>jit</code> language, which requires

  1264. <samp>--enable-host-shared</samp> to be included with <code>all</code>.

  1265. </p>

  1266. </dd>

  1267. <dt><code>--enable-stage1-languages=<var>lang1</var>,<var>lang2</var>,&hellip;</code></dt>

  1268. <dd><p>Specify that a particular subset of compilers and their runtime

  1269. libraries should be built with the system C compiler during stage 1 of

  1270. the bootstrap process, rather than only in later stages with the

  1271. bootstrapped C compiler.  The list of valid values is the same as for

  1272. <samp>--enable-languages</samp>, and the option <code>all</code> will select all

  1273. of the languages enabled by <samp>--enable-languages</samp>.  This option is

  1274. primarily useful for GCC development; for instance, when a development

  1275. version of the compiler cannot bootstrap due to compiler bugs, or when

  1276. one is debugging front ends other than the C front end.  When this

  1277. option is used, one can then build the target libraries for the

  1278. specified languages with the stage-1 compiler by using <code>make

  1279. stage1-bubble all-target</code>, or run the testsuite on the stage-1 compiler

  1280. for the specified languages using <code>make stage1-start check-gcc</code>.

  1281. </p>

  1282. </dd>

  1283. <dt><code>--disable-libada</code></dt>

  1284. <dd><p>Specify that the run-time libraries and tools used by GNAT should not

  1285. be built.  This can be useful for debugging, or for compatibility with

  1286. previous Ada build procedures, when it was required to explicitly

  1287. do a &lsquo;<samp>make -C gcc gnatlib_and_tools</samp>&rsquo;.

  1288. </p>

  1289. </dd>

  1290. <dt><code>--disable-libsanitizer</code></dt>

  1291. <dd><p>Specify that the run-time libraries for the various sanitizers should

  1292. not be built.

  1293. </p>

  1294. </dd>

  1295. <dt><code>--disable-libssp</code></dt>

  1296. <dd><p>Specify that the run-time libraries for stack smashing protection

  1297. should not be built or linked against.  On many targets library support

  1298. is provided by the C library instead.

  1299. </p>

  1300. </dd>

  1301. <dt><code>--disable-libquadmath</code></dt>

  1302. <dd><p>Specify that the GCC quad-precision math library should not be built.

  1303. On some systems, the library is required to be linkable when building

  1304. the Fortran front end, unless <samp>--disable-libquadmath-support</samp>

  1305. is used.

  1306. </p>

  1307. </dd>

  1308. <dt><code>--disable-libquadmath-support</code></dt>

  1309. <dd><p>Specify that the Fortran front end and <code>libgfortran</code> do not add

  1310. support for <code>libquadmath</code> on systems supporting it.

  1311. </p>

  1312. </dd>

  1313. <dt><code>--disable-libgomp</code></dt>

  1314. <dd><p>Specify that the GNU Offloading and Multi Processing Runtime Library

  1315. should not be built.

  1316. </p>

  1317. </dd>

  1318. <dt><code>--disable-libvtv</code></dt>

  1319. <dd><p>Specify that the run-time libraries used by vtable verification

  1320. should not be built.

  1321. </p>

  1322. </dd>

  1323. <dt><code>--with-dwarf2</code></dt>

  1324. <dd><p>Specify that the compiler should

  1325. use DWARF 2 debugging information as the default.

  1326. </p>

  1327. </dd>

  1328. <dt><code>--with-advance-toolchain=<var>at</var></code></dt>

  1329. <dd><p>On 64-bit PowerPC Linux systems, configure the compiler to use the

  1330. header files, library files, and the dynamic linker from the Advance

  1331. Toolchain release <var>at</var> instead of the default versions that are

  1332. provided by the Linux distribution.  In general, this option is

  1333. intended for the developers of GCC, and it is not intended for general

  1334. use.

  1335. </p>

  1336. </dd>

  1337. <dt><code>--enable-targets=all</code></dt>

  1338. <dt><code>--enable-targets=<var>target_list</var></code></dt>

  1339. <dd><p>Some GCC targets, e.g. powerpc64-linux, build bi-arch compilers.

  1340. These are compilers that are able to generate either 64-bit or 32-bit

  1341. code.  Typically, the corresponding 32-bit target, e.g.

  1342. powerpc-linux for powerpc64-linux, only generates 32-bit code.  This

  1343. option enables the 32-bit target to be a bi-arch compiler, which is

  1344. useful when you want a bi-arch compiler that defaults to 32-bit, and

  1345. you are building a bi-arch or multi-arch binutils in a combined tree.

  1346. On mips-linux, this will build a tri-arch compiler (ABI o32/n32/64),

  1347. defaulted to o32.

  1348. Currently, this option only affects sparc-linux, powerpc-linux, x86-linux,

  1349. mips-linux and s390-linux.

  1350. </p>

  1351. </dd>

  1352. <dt><code>--enable-default-pie</code></dt>

  1353. <dd><p>Turn on <samp>-fPIE</samp> and <samp>-pie</samp> by default.

  1354. </p>

  1355. </dd>

  1356. <dt><code>--enable-secureplt</code></dt>

  1357. <dd><p>This option enables <samp>-msecure-plt</samp> by default for powerpc-linux.

  1358. See &ldquo;RS/6000 and PowerPC Options&rdquo; in the main manual

  1359. </p>

  1360. </dd>

  1361. <dt><code>--enable-default-ssp</code></dt>

  1362. <dd><p>Turn on <samp>-fstack-protector-strong</samp> by default.

  1363. </p>

  1364. </dd>

  1365. <dt><code>--enable-cld</code></dt>

  1366. <dd><p>This option enables <samp>-mcld</samp> by default for 32-bit x86 targets.

  1367. See &ldquo;i386 and x86-64 Options&rdquo; in the main manual

  1368. </p>

  1369. </dd>

  1370. <dt><code>--enable-large-address-aware</code></dt>

  1371. <dd><p>The <samp>--enable-large-address-aware</samp> option arranges for MinGW

  1372. executables to be linked using the <samp>--large-address-aware</samp>

  1373. option, that enables the use of more than 2GB of memory.  If GCC is

  1374. configured with this option, its effects can be reversed by passing the

  1375. <samp>-Wl,--disable-large-address-aware</samp> option to the so-configured

  1376. compiler driver.

  1377. </p>

  1378. </dd>

  1379. <dt><code>--enable-win32-registry</code></dt>

  1380. <dt><code>--enable-win32-registry=<var>key</var></code></dt>

  1381. <dt><code>--disable-win32-registry</code></dt>

  1382. <dd><p>The <samp>--enable-win32-registry</samp> option enables Microsoft Windows-hosted GCC

  1383. to look up installations paths in the registry using the following key:

  1384. </p>

  1385. <div class="smallexample">

  1386. <pre class="smallexample"><code>HKEY_LOCAL_MACHINE\SOFTWARE\Free Software Foundation\<var>key</var></code>

  1387. </pre></div>

  1388. 

  1389. <p><var>key</var> defaults to GCC version number, and can be overridden by the

  1390. <samp>--enable-win32-registry=<var>key</var></samp> option.  Vendors and distributors

  1391. who use custom installers are encouraged to provide a different key,

  1392. perhaps one comprised of vendor name and GCC version number, to

  1393. avoid conflict with existing installations.  This feature is enabled

  1394. by default, and can be disabled by <samp>--disable-win32-registry</samp>

  1395. option.  This option has no effect on the other hosts.

  1396. </p>

  1397. </dd>

  1398. <dt><code>--nfp</code></dt>

  1399. <dd><p>Specify that the machine does not have a floating point unit.  This

  1400. option only applies to &lsquo;<samp>m68k-sun-sunos<var>n</var></samp>&rsquo;.  On any other

  1401. system, <samp>--nfp</samp> has no effect.

  1402. </p>

  1403. </dd>

  1404. <dt><code>--enable-werror</code></dt>

  1405. <dt><code>--disable-werror</code></dt>

  1406. <dt><code>--enable-werror=yes</code></dt>

  1407. <dt><code>--enable-werror=no</code></dt>

  1408. <dd><p>When you specify this option, it controls whether certain files in the

  1409. compiler are built with <samp>-Werror</samp> in bootstrap stage2 and later.

  1410. If you don&rsquo;t specify it, <samp>-Werror</samp> is turned on for the main

  1411. development trunk.  However it defaults to off for release branches and

  1412. final releases.  The specific files which get <samp>-Werror</samp> are

  1413. controlled by the Makefiles.

  1414. </p>

  1415. </dd>

  1416. <dt><code>--enable-checking</code></dt>

  1417. <dt><code>--disable-checking</code></dt>

  1418. <dt><code>--enable-checking=<var>list</var></code></dt>

  1419. <dd><p>This option controls performing internal consistency checks in the compiler.

  1420. It does not change the generated code, but adds error checking of the

  1421. requested complexity.  This slows down the compiler and may only work

  1422. properly if you are building the compiler with GCC.

  1423. </p>

  1424. <p>When the option is not specified, the active set of checks depends on context.

  1425. Namely, bootstrap stage 1 defaults to &lsquo;<samp>--enable-checking=yes</samp>&rsquo;, builds

  1426. from release branches or release archives default to

  1427. &lsquo;<samp>--enable-checking=release</samp>&rsquo;, and otherwise

  1428. &lsquo;<samp>--enable-checking=yes,extra</samp>&rsquo; is used.  When the option is

  1429. specified without a <var>list</var>, the result is the same as

  1430. &lsquo;<samp>--enable-checking=yes</samp>&rsquo;.  Likewise, &lsquo;<samp>--disable-checking</samp>&rsquo; is

  1431. equivalent to &lsquo;<samp>--enable-checking=no</samp>&rsquo;.

  1432. </p>

  1433. <p>The categories of checks available in <var>list</var> are &lsquo;<samp>yes</samp>&rsquo; (most common

  1434. checks &lsquo;<samp>assert,misc,gc,gimple,rtlflag,runtime,tree,types</samp>&rsquo;), &lsquo;<samp>no</samp>&rsquo;

  1435. (no checks at all), &lsquo;<samp>all</samp>&rsquo; (all but &lsquo;<samp>valgrind</samp>&rsquo;), &lsquo;<samp>release</samp>&rsquo;

  1436. (cheapest checks &lsquo;<samp>assert,runtime</samp>&rsquo;) or &lsquo;<samp>none</samp>&rsquo; (same as &lsquo;<samp>no</samp>&rsquo;).

  1437. &lsquo;<samp>release</samp>&rsquo; checks are always on and to disable them

  1438. &lsquo;<samp>--disable-checking</samp>&rsquo; or &lsquo;<samp>--enable-checking=no[,&lt;other checks&gt;]</samp>&rsquo;

  1439. must be explicitly requested.  Disabling assertions makes the compiler and

  1440. runtime slightly faster but increases the risk of undetected internal errors

  1441. causing wrong code to be generated.

  1442. </p>

  1443. <p>Individual checks can be enabled with these flags: &lsquo;<samp>assert</samp>&rsquo;, &lsquo;<samp>df</samp>&rsquo;,

  1444. &lsquo;<samp>extra</samp>&rsquo;, &lsquo;<samp>fold</samp>&rsquo;, &lsquo;<samp>gc</samp>&rsquo;, &lsquo;<samp>gcac</samp>&rsquo;, &lsquo;<samp>gimple</samp>&rsquo;,

  1445. &lsquo;<samp>misc</samp>&rsquo;, &lsquo;<samp>rtl</samp>&rsquo;, &lsquo;<samp>rtlflag</samp>&rsquo;, &lsquo;<samp>runtime</samp>&rsquo;, &lsquo;<samp>tree</samp>&rsquo;,

  1446. &lsquo;<samp>types</samp>&rsquo; and &lsquo;<samp>valgrind</samp>&rsquo;.  &lsquo;<samp>extra</samp>&rsquo; extends &lsquo;<samp>misc</samp>&rsquo;

  1447. checking with extra checks that might affect code generation and should

  1448. therefore not differ between stage1 and later stages in bootstrap.

  1449. </p>

  1450. <p>The &lsquo;<samp>valgrind</samp>&rsquo; check requires the external <code>valgrind</code> simulator,

  1451. available from <a href="http://valgrind.org/">http://valgrind.org/</a>.  The &lsquo;<samp>rtl</samp>&rsquo; checks are

  1452. expensive and the &lsquo;<samp>df</samp>&rsquo;, &lsquo;<samp>gcac</samp>&rsquo; and &lsquo;<samp>valgrind</samp>&rsquo; checks are very

  1453. expensive.

  1454. </p>

  1455. </dd>

  1456. <dt><code>--disable-stage1-checking</code></dt>

  1457. <dt><code>--enable-stage1-checking</code></dt>

  1458. <dt><code>--enable-stage1-checking=<var>list</var></code></dt>

  1459. <dd><p>This option affects only bootstrap build.  If no <samp>--enable-checking</samp>

  1460. option is specified the stage1 compiler is built with &lsquo;<samp>yes</samp>&rsquo; checking

  1461. enabled, otherwise the stage1 checking flags are the same as specified by

  1462. <samp>--enable-checking</samp>.  To build the stage1 compiler with

  1463. different checking options use <samp>--enable-stage1-checking</samp>.

  1464. The list of checking options is the same as for <samp>--enable-checking</samp>.

  1465. If your system is too slow or too small to bootstrap a released compiler

  1466. with checking for stage1 enabled, you can use &lsquo;<samp>--disable-stage1-checking</samp>&rsquo;

  1467. to disable checking for the stage1 compiler.

  1468. </p>

  1469. </dd>

  1470. <dt><code>--enable-coverage</code></dt>

  1471. <dt><code>--enable-coverage=<var>level</var></code></dt>

  1472. <dd><p>With this option, the compiler is built to collect self coverage

  1473. information, every time it is run.  This is for internal development

  1474. purposes, and only works when the compiler is being built with gcc.  The

  1475. <var>level</var> argument controls whether the compiler is built optimized or

  1476. not, values are &lsquo;<samp>opt</samp>&rsquo; and &lsquo;<samp>noopt</samp>&rsquo;.  For coverage analysis you

  1477. want to disable optimization, for performance analysis you want to

  1478. enable optimization.  When coverage is enabled, the default level is

  1479. without optimization.

  1480. </p>

  1481. </dd>

  1482. <dt><code>--enable-gather-detailed-mem-stats</code></dt>

  1483. <dd><p>When this option is specified more detailed information on memory

  1484. allocation is gathered.  This information is printed when using

  1485. <samp>-fmem-report</samp>.

  1486. </p>

  1487. </dd>

  1488. <dt><code>--enable-valgrind-annotations</code></dt>

  1489. <dd><p>Mark selected memory related operations in the compiler when run under

  1490. valgrind to suppress false positives.

  1491. </p>

  1492. </dd>

  1493. <dt><code>--enable-nls</code></dt>

  1494. <dt><code>--disable-nls</code></dt>

  1495. <dd><p>The <samp>--enable-nls</samp> option enables Native Language Support (NLS),

  1496. which lets GCC output diagnostics in languages other than American

  1497. English.  Native Language Support is enabled by default if not doing a

  1498. canadian cross build.  The <samp>--disable-nls</samp> option disables NLS.

  1499. </p>

  1500. </dd>

  1501. <dt><code>--with-included-gettext</code></dt>

  1502. <dd><p>If NLS is enabled, the <samp>--with-included-gettext</samp> option causes the build

  1503. procedure to prefer its copy of GNU <code>gettext</code>.

  1504. </p>

  1505. </dd>

  1506. <dt><code>--with-catgets</code></dt>

  1507. <dd><p>If NLS is enabled, and if the host lacks <code>gettext</code> but has the

  1508. inferior <code>catgets</code> interface, the GCC build procedure normally

  1509. ignores <code>catgets</code> and instead uses GCC&rsquo;s copy of the GNU

  1510. <code>gettext</code> library.  The <samp>--with-catgets</samp> option causes the

  1511. build procedure to use the host&rsquo;s <code>catgets</code> in this situation.

  1512. </p>

  1513. </dd>

  1514. <dt><code>--with-libiconv-prefix=<var>dir</var></code></dt>

  1515. <dd><p>Search for libiconv header files in <samp><var>dir</var>/include</samp> and

  1516. libiconv library files in <samp><var>dir</var>/lib</samp>.

  1517. </p>

  1518. </dd>

  1519. <dt><code>--enable-obsolete</code></dt>

  1520. <dd><p>Enable configuration for an obsoleted system.  If you attempt to

  1521. configure GCC for a system (build, host, or target) which has been

  1522. obsoleted, and you do not specify this flag, configure will halt with an

  1523. error message.

  1524. </p>

  1525. <p>All support for systems which have been obsoleted in one release of GCC

  1526. is removed entirely in the next major release, unless someone steps

  1527. forward to maintain the port.

  1528. </p>

  1529. </dd>

  1530. <dt><code>--enable-decimal-float</code></dt>

  1531. <dt><code>--enable-decimal-float=yes</code></dt>

  1532. <dt><code>--enable-decimal-float=no</code></dt>

  1533. <dt><code>--enable-decimal-float=bid</code></dt>

  1534. <dt><code>--enable-decimal-float=dpd</code></dt>

  1535. <dt><code>--disable-decimal-float</code></dt>

  1536. <dd><p>Enable (or disable) support for the C decimal floating point extension

  1537. that is in the IEEE 754-2008 standard.  This is enabled by default only

  1538. on PowerPC, i386, and x86_64 GNU/Linux systems.  Other systems may also

  1539. support it, but require the user to specifically enable it.  You can

  1540. optionally control which decimal floating point format is used (either

  1541. &lsquo;<samp>bid</samp>&rsquo; or &lsquo;<samp>dpd</samp>&rsquo;).  The &lsquo;<samp>bid</samp>&rsquo; (binary integer decimal)

  1542. format is default on i386 and x86_64 systems, and the &lsquo;<samp>dpd</samp>&rsquo;

  1543. (densely packed decimal) format is default on PowerPC systems.

  1544. </p>

  1545. </dd>

  1546. <dt><code>--enable-fixed-point</code></dt>

  1547. <dt><code>--disable-fixed-point</code></dt>

  1548. <dd><p>Enable (or disable) support for C fixed-point arithmetic.

  1549. This option is enabled by default for some targets (such as MIPS) which

  1550. have hardware-support for fixed-point operations.  On other targets, you

  1551. may enable this option manually.

  1552. </p>

  1553. </dd>

  1554. <dt><code>--with-long-double-128</code></dt>

  1555. <dd><p>Specify if <code>long double</code> type should be 128-bit by default on selected

  1556. GNU/Linux architectures.  If using <code>--without-long-double-128</code>,

  1557. <code>long double</code> will be by default 64-bit, the same as <code>double</code> type.

  1558. When neither of these configure options are used, the default will be

  1559. 128-bit <code>long double</code> when built against GNU C Library 2.4 and later,

  1560. 64-bit <code>long double</code> otherwise.

  1561. </p>

  1562. </dd>

  1563. <dt><code>--with-long-double-format=ibm</code></dt>

  1564. <dt><code>--with-long-double-format=ieee</code></dt>

  1565. <dd><p>Specify whether <code>long double</code> uses the IBM extended double format

  1566. or the IEEE 128-bit floating point format on PowerPC Linux systems.

  1567. This configuration switch will only work on little endian PowerPC

  1568. Linux systems and on big endian 64-bit systems where the default cpu

  1569. is at least power7 (i.e. <samp>--with-cpu=power7</samp>,

  1570. <samp>--with-cpu=power8</samp>, or <samp>--with-cpu=power9</samp> is used).

  1571. </p>

  1572. <p>If you use the <samp>--with-long-double-64</samp> configuration option,

  1573. the <samp>--with-long-double-format=ibm</samp> and

  1574. <samp>--with-long-double-format=ieee</samp> options are ignored.

  1575. </p>

  1576. <p>The default <code>long double</code> format is to use IBM extended double.

  1577. Until all of the libraries are converted to use IEEE 128-bit floating

  1578. point, it is not recommended to use

  1579. <samp>--with-long-double-format=ieee</samp>.

  1580. </p>

  1581. <p>On little endian PowerPC Linux systems, if you explicitly set the

  1582. <code>long double</code> type, it will build multilibs to allow you to

  1583. select either <code>long double</code> format, unless you disable multilibs

  1584. with the <code>--disable-multilib</code> option.  At present,

  1585. <code>long double</code> multilibs are not built on big endian PowerPC Linux

  1586. systems.  If you are building multilibs, you will need to configure

  1587. the compiler using the <samp>--with-system-zlib</samp> option.

  1588. </p>

  1589. <p>If you do not set the <code>long double</code> type explicitly, no multilibs

  1590. will be generated.

  1591. </p>

  1592. </dd>

  1593. <dt><code>--enable-fdpic</code></dt>

  1594. <dd><p>On SH Linux systems, generate ELF FDPIC code.

  1595. </p>

  1596. </dd>

  1597. <dt><code>--with-gmp=<var>pathname</var></code></dt>

  1598. <dt><code>--with-gmp-include=<var>pathname</var></code></dt>

  1599. <dt><code>--with-gmp-lib=<var>pathname</var></code></dt>

  1600. <dt><code>--with-mpfr=<var>pathname</var></code></dt>

  1601. <dt><code>--with-mpfr-include=<var>pathname</var></code></dt>

  1602. <dt><code>--with-mpfr-lib=<var>pathname</var></code></dt>

  1603. <dt><code>--with-mpc=<var>pathname</var></code></dt>

  1604. <dt><code>--with-mpc-include=<var>pathname</var></code></dt>

  1605. <dt><code>--with-mpc-lib=<var>pathname</var></code></dt>

  1606. <dd><p>If you want to build GCC but do not have the GMP library, the MPFR

  1607. library and/or the MPC library installed in a standard location and

  1608. do not have their sources present in the GCC source tree then you

  1609. can explicitly specify the directory where they are installed

  1610. (&lsquo;<samp>--with-gmp=<var>gmpinstalldir</var></samp>&rsquo;,

  1611. &lsquo;<samp>--with-mpfr=<var>mpfrinstalldir</var></samp>&rsquo;,

  1612. &lsquo;<samp>--with-mpc=<var>mpcinstalldir</var></samp>&rsquo;).  The

  1613. <samp>--with-gmp=<var>gmpinstalldir</var></samp> option is shorthand for

  1614. <samp>--with-gmp-lib=<var>gmpinstalldir</var>/lib</samp> and

  1615. <samp>--with-gmp-include=<var>gmpinstalldir</var>/include</samp>.  Likewise the

  1616. <samp>--with-mpfr=<var>mpfrinstalldir</var></samp> option is shorthand for

  1617. <samp>--with-mpfr-lib=<var>mpfrinstalldir</var>/lib</samp> and

  1618. <samp>--with-mpfr-include=<var>mpfrinstalldir</var>/include</samp>, also the

  1619. <samp>--with-mpc=<var>mpcinstalldir</var></samp> option is shorthand for

  1620. <samp>--with-mpc-lib=<var>mpcinstalldir</var>/lib</samp> and

  1621. <samp>--with-mpc-include=<var>mpcinstalldir</var>/include</samp>.  If these

  1622. shorthand assumptions are not correct, you can use the explicit

  1623. include and lib options directly.  You might also need to ensure the

  1624. shared libraries can be found by the dynamic linker when building and

  1625. using GCC, for example by setting the runtime shared library path

  1626. variable (<code>LD_LIBRARY_PATH</code> on GNU/Linux and Solaris systems).

  1627. </p>

  1628. <p>These flags are applicable to the host platform only.  When building

  1629. a cross compiler, they will not be used to configure target libraries.

  1630. </p>

  1631. </dd>

  1632. <dt><code>--with-isl=<var>pathname</var></code></dt>

  1633. <dt><code>--with-isl-include=<var>pathname</var></code></dt>

  1634. <dt><code>--with-isl-lib=<var>pathname</var></code></dt>

  1635. <dd><p>If you do not have the isl library installed in a standard location and you

  1636. want to build GCC, you can explicitly specify the directory where it is

  1637. installed (&lsquo;<samp>--with-isl=<var>islinstalldir</var></samp>&rsquo;). The

  1638. <samp>--with-isl=<var>islinstalldir</var></samp> option is shorthand for

  1639. <samp>--with-isl-lib=<var>islinstalldir</var>/lib</samp> and

  1640. <samp>--with-isl-include=<var>islinstalldir</var>/include</samp>. If this

  1641. shorthand assumption is not correct, you can use the explicit

  1642. include and lib options directly.

  1643. </p>

  1644. <p>These flags are applicable to the host platform only.  When building

  1645. a cross compiler, they will not be used to configure target libraries.

  1646. </p>

  1647. </dd>

  1648. <dt><code>--with-stage1-ldflags=<var>flags</var></code></dt>

  1649. <dd><p>This option may be used to set linker flags to be used when linking

  1650. stage 1 of GCC.  These are also used when linking GCC if configured with

  1651. <samp>--disable-bootstrap</samp>.  If <samp>--with-stage1-libs</samp> is not set to a

  1652. value, then the default is &lsquo;<samp>-static-libstdc++ -static-libgcc</samp>&rsquo;, if

  1653. supported.

  1654. </p>

  1655. </dd>

  1656. <dt><code>--with-stage1-libs=<var>libs</var></code></dt>

  1657. <dd><p>This option may be used to set libraries to be used when linking stage 1

  1658. of GCC.  These are also used when linking GCC if configured with

  1659. <samp>--disable-bootstrap</samp>.

  1660. </p>

  1661. </dd>

  1662. <dt><code>--with-boot-ldflags=<var>flags</var></code></dt>

  1663. <dd><p>This option may be used to set linker flags to be used when linking

  1664. stage 2 and later when bootstrapping GCC.  If &ndash;with-boot-libs

  1665. is not is set to a value, then the default is

  1666. &lsquo;<samp>-static-libstdc++ -static-libgcc</samp>&rsquo;.

  1667. </p>

  1668. </dd>

  1669. <dt><code>--with-boot-libs=<var>libs</var></code></dt>

  1670. <dd><p>This option may be used to set libraries to be used when linking stage 2

  1671. and later when bootstrapping GCC.

  1672. </p>

  1673. </dd>

  1674. <dt><code>--with-debug-prefix-map=<var>map</var></code></dt>

  1675. <dd><p>Convert source directory names using <samp>-fdebug-prefix-map</samp> when

  1676. building runtime libraries.  &lsquo;<samp><var>map</var></samp>&rsquo; is a space-separated

  1677. list of maps of the form &lsquo;<samp><var>old</var>=<var>new</var></samp>&rsquo;.

  1678. </p>

  1679. </dd>

  1680. <dt><code>--enable-linker-build-id</code></dt>

  1681. <dd><p>Tells GCC to pass <samp>--build-id</samp> option to the linker for all final

  1682. links (links performed without the <samp>-r</samp> or <samp>--relocatable</samp>

  1683. option), if the linker supports it.  If you specify

  1684. <samp>--enable-linker-build-id</samp>, but your linker does not

  1685. support <samp>--build-id</samp> option, a warning is issued and the

  1686. <samp>--enable-linker-build-id</samp> option is ignored.  The default is off.

  1687. </p>

  1688. </dd>

  1689. <dt><code>--with-linker-hash-style=<var>choice</var></code></dt>

  1690. <dd><p>Tells GCC to pass <samp>--hash-style=<var>choice</var></samp> option to the

  1691. linker for all final links. <var>choice</var> can be one of

  1692. &lsquo;<samp>sysv</samp>&rsquo;, &lsquo;<samp>gnu</samp>&rsquo;, and &lsquo;<samp>both</samp>&rsquo; where &lsquo;<samp>sysv</samp>&rsquo; is the default.

  1693. </p>

  1694. </dd>

  1695. <dt><code>--enable-gnu-unique-object</code></dt>

  1696. <dt><code>--disable-gnu-unique-object</code></dt>

  1697. <dd><p>Tells GCC to use the gnu_unique_object relocation for C++ template

  1698. static data members and inline function local statics.  Enabled by

  1699. default for a toolchain with an assembler that accepts it and

  1700. GLIBC 2.11 or above, otherwise disabled.

  1701. </p>

  1702. </dd>

  1703. <dt><code>--with-diagnostics-color=<var>choice</var></code></dt>

  1704. <dd><p>Tells GCC to use <var>choice</var> as the default for <samp>-fdiagnostics-color=</samp>

  1705. option (if not used explicitly on the command line).  <var>choice</var>

  1706. can be one of &lsquo;<samp>never</samp>&rsquo;, &lsquo;<samp>auto</samp>&rsquo;, &lsquo;<samp>always</samp>&rsquo;, and &lsquo;<samp>auto-if-env</samp>&rsquo;

  1707. where &lsquo;<samp>auto</samp>&rsquo; is the default.  &lsquo;<samp>auto-if-env</samp>&rsquo; makes

  1708. <samp>-fdiagnostics-color=auto</samp> the default if <code>GCC_COLORS</code>

  1709. is present and non-empty in the environment of the compiler, and

  1710. <samp>-fdiagnostics-color=never</samp> otherwise.

  1711. </p>

  1712. </dd>

  1713. <dt><code>--with-diagnostics-urls=<var>choice</var></code></dt>

  1714. <dd><p>Tells GCC to use <var>choice</var> as the default for <samp>-fdiagnostics-urls=</samp>

  1715. option (if not used explicitly on the command line).  <var>choice</var>

  1716. can be one of &lsquo;<samp>never</samp>&rsquo;, &lsquo;<samp>auto</samp>&rsquo;, &lsquo;<samp>always</samp>&rsquo;, and &lsquo;<samp>auto-if-env</samp>&rsquo;

  1717. where &lsquo;<samp>auto</samp>&rsquo; is the default.  &lsquo;<samp>auto-if-env</samp>&rsquo; makes

  1718. <samp>-fdiagnostics-urls=auto</samp> the default if <code>GCC_URLS</code>

  1719. or <code>TERM_URLS</code> is present and non-empty in the environment of the

  1720. compiler, and <samp>-fdiagnostics-urls=never</samp> otherwise.

  1721. </p>

  1722. </dd>

  1723. <dt><code>--enable-lto</code></dt>

  1724. <dt><code>--disable-lto</code></dt>

  1725. <dd><p>Enable support for link-time optimization (LTO).  This is enabled by

  1726. default, and may be disabled using <samp>--disable-lto</samp>.

  1727. </p>

  1728. </dd>

  1729. <dt><code>--enable-linker-plugin-configure-flags=FLAGS</code></dt>

  1730. <dt><code>--enable-linker-plugin-flags=FLAGS</code></dt>

  1731. <dd><p>By default, linker plugins (such as the LTO plugin) are built for the

  1732. host system architecture.  For the case that the linker has a

  1733. different (but run-time compatible) architecture, these flags can be

  1734. specified to build plugins that are compatible to the linker.  For

  1735. example, if you are building GCC for a 64-bit x86_64

  1736. (&lsquo;<samp>x86_64-pc-linux-gnu</samp>&rsquo;) host system, but have a 32-bit x86

  1737. GNU/Linux (&lsquo;<samp>i686-pc-linux-gnu</samp>&rsquo;) linker executable (which is

  1738. executable on the former system), you can configure GCC as follows for

  1739. getting compatible linker plugins:

  1740. </p>

  1741. <div class="smallexample">

  1742. <pre class="smallexample">% <var>srcdir</var>/configure \

  1743.     --host=x86_64-pc-linux-gnu \

  1744.     --enable-linker-plugin-configure-flags=--host=i686-pc-linux-gnu \

  1745.     --enable-linker-plugin-flags='CC=gcc\ -m32\ -Wl,-rpath,[...]/i686-pc-linux-gnu/lib'

  1746. </pre></div>

  1747. 

  1748. </dd>

  1749. <dt><code>--with-plugin-ld=<var>pathname</var></code></dt>

  1750. <dd><p>Enable an alternate linker to be used at link-time optimization (LTO)

  1751. link time when <samp>-fuse-linker-plugin</samp> is enabled.

  1752. This linker should have plugin support such as gold starting with

  1753. version 2.20 or GNU ld starting with version 2.21.

  1754. See <samp>-fuse-linker-plugin</samp> for details.

  1755. </p>

  1756. </dd>

  1757. <dt><code>--enable-canonical-system-headers</code></dt>

  1758. <dt><code>--disable-canonical-system-headers</code></dt>

  1759. <dd><p>Enable system header path canonicalization for <samp>libcpp</samp>.  This can

  1760. produce shorter header file paths in diagnostics and dependency output

  1761. files, but these changed header paths may conflict with some compilation

  1762. environments.  Enabled by default, and may be disabled using

  1763. <samp>--disable-canonical-system-headers</samp>.

  1764. </p>

  1765. </dd>

  1766. <dt><code>--with-glibc-version=<var>major</var>.<var>minor</var></code></dt>

  1767. <dd><p>Tell GCC that when the GNU C Library (glibc) is used on the target it

  1768. will be version <var>major</var>.<var>minor</var> or later.  Normally this can

  1769. be detected from the C library&rsquo;s header files, but this option may be

  1770. needed when bootstrapping a cross toolchain without the header files

  1771. available for building the initial bootstrap compiler.

  1772. </p>

  1773. <p>If GCC is configured with some multilibs that use glibc and some that

  1774. do not, this option applies only to the multilibs that use glibc.

  1775. However, such configurations may not work well as not all the relevant

  1776. configuration in GCC is on a per-multilib basis.

  1777. </p>

  1778. </dd>

  1779. <dt><code>--enable-as-accelerator-for=<var>target</var></code></dt>

  1780. <dd><p>Build as offload target compiler. Specify offload host triple by <var>target</var>.

  1781. </p>

  1782. </dd>

  1783. <dt><code>--enable-offload-targets=<var>target1</var>[=<var>path1</var>],&hellip;,<var>targetN</var>[=<var>pathN</var>]</code></dt>

  1784. <dd><p>Enable offloading to targets <var>target1</var>, &hellip;, <var>targetN</var>.

  1785. Offload compilers are expected to be already installed.  Default search

  1786. path for them is <samp><var>exec-prefix</var></samp>, but it can be changed by

  1787. specifying paths <var>path1</var>, &hellip;, <var>pathN</var>.

  1788. </p>

  1789. <div class="smallexample">

  1790. <pre class="smallexample">% <var>srcdir</var>/configure \

  1791.     --enable-offload-targets=x86_64-intelmicemul-linux-gnu=/path/to/x86_64/compiler,nvptx-none,hsa

  1792. </pre></div>

  1793. 

  1794. <p>If &lsquo;<samp>hsa</samp>&rsquo; is specified as one of the targets, the compiler will be

  1795. built with support for HSA GPU accelerators.  Because the same

  1796. compiler will emit the accelerator code, no path should be specified.

  1797. </p>

  1798. </dd>

  1799. <dt><code>--with-hsa-runtime=<var>pathname</var></code></dt>

  1800. <dt><code>--with-hsa-runtime-include=<var>pathname</var></code></dt>

  1801. <dt><code>--with-hsa-runtime-lib=<var>pathname</var></code></dt>

  1802. <dd>

  1803. <p>If you configure GCC with HSA offloading but do not have the HSA

  1804. run-time library installed in a standard location then you can

  1805. explicitly specify the directory where they are installed.  The

  1806. <samp>--with-hsa-runtime=<var>hsainstalldir</var></samp> option is a

  1807. shorthand for

  1808. <samp>--with-hsa-runtime-lib=<var>hsainstalldir</var>/lib</samp> and

  1809. <samp>--with-hsa-runtime-include=<var>hsainstalldir</var>/include</samp>.

  1810. </p>

  1811. </dd>

  1812. <dt><code>--enable-cet</code></dt>

  1813. <dt><code>--disable-cet</code></dt>

  1814. <dd><p>Enable building target run-time libraries with control-flow

  1815. instrumentation, see <samp>-fcf-protection</samp> option.  When

  1816. <code>--enable-cet</code> is specified target libraries are configured

  1817. to add <samp>-fcf-protection</samp> and, if needed, other target

  1818. specific options to a set of building options.

  1819. </p>

  1820. <p>The option is disabled by default.  When <code>--enable-cet=auto</code>

  1821. is used, it is enabled on Linux/x86 if target binutils

  1822. supports <code>Intel CET</code> instructions and disabled otherwise.

  1823. In this case the target libraries are configured to get additional

  1824. <samp>-fcf-protection</samp> option.

  1825. </p>

  1826. </dd>

  1827. <dt><code>--with-riscv-attribute=&lsquo;<samp>yes</samp>&rsquo;, &lsquo;<samp>no</samp>&rsquo; or &lsquo;<samp>default</samp>&rsquo;</code></dt>

  1828. <dd><p>Generate RISC-V attribute by default, in order to record extra build

  1829. information in object.

  1830. </p>

  1831. <p>The option is disabled by default. It is enabled on RISC-V/ELF (bare-metal)

  1832. target if target binutils supported.

  1833. </p></dd>

  1834. </dl>

  1835. 

  1836. <a name="Cross-Compiler-Specific-Options"></a>

  1837. <h4 class="subheading">Cross-Compiler-Specific Options</h4>

  1838. <p>The following options only apply to building cross compilers.

  1839. </p>

  1840. <dl compact="compact">

  1841. <dt><code>--with-toolexeclibdir=<var>dir</var></code></dt>

  1842. <dd><p>Specify the installation directory for libraries built with a cross compiler.

  1843. The default is <samp>${gcc_tooldir}/lib</samp>.

  1844. </p>

  1845. </dd>

  1846. <dt><code>--with-sysroot</code></dt>

  1847. <dt><code>--with-sysroot=<var>dir</var></code></dt>

  1848. <dd><p>Tells GCC to consider <var>dir</var> as the root of a tree that contains

  1849. (a subset of) the root filesystem of the target operating system.

  1850. Target system headers, libraries and run-time object files will be

  1851. searched for in there.  More specifically, this acts as if

  1852. <samp>--sysroot=<var>dir</var></samp> was added to the default options of the built

  1853. compiler.  The specified directory is not copied into the

  1854. install tree, unlike the options <samp>--with-headers</samp> and

  1855. <samp>--with-libs</samp> that this option obsoletes.  The default value,

  1856. in case <samp>--with-sysroot</samp> is not given an argument, is

  1857. <samp>${gcc_tooldir}/sys-root</samp>.  If the specified directory is a

  1858. subdirectory of <samp>${exec_prefix}</samp>, then it will be found relative to

  1859. the GCC binaries if the installation tree is moved.

  1860. </p>

  1861. <p>This option affects the system root for the compiler used to build

  1862. target libraries (which runs on the build system) and the compiler newly

  1863. installed with <code>make install</code>; it does not affect the compiler which is

  1864. used to build GCC itself.

  1865. </p>

  1866. <p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp>

  1867. option then the compiler will search that directory within <var>dirname</var> for

  1868. native system headers rather than the default <samp>/usr/include</samp>.

  1869. </p>

  1870. </dd>

  1871. <dt><code>--with-build-sysroot</code></dt>

  1872. <dt><code>--with-build-sysroot=<var>dir</var></code></dt>

  1873. <dd><p>Tells GCC to consider <var>dir</var> as the system root (see

  1874. <samp>--with-sysroot</samp>) while building target libraries, instead of

  1875. the directory specified with <samp>--with-sysroot</samp>.  This option is

  1876. only useful when you are already using <samp>--with-sysroot</samp>.  You

  1877. can use <samp>--with-build-sysroot</samp> when you are configuring with

  1878. <samp>--prefix</samp> set to a directory that is different from the one in

  1879. which you are installing GCC and your target libraries.

  1880. </p>

  1881. <p>This option affects the system root for the compiler used to build

  1882. target libraries (which runs on the build system); it does not affect

  1883. the compiler which is used to build GCC itself.

  1884. </p>

  1885. <p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp>

  1886. option then the compiler will search that directory within <var>dirname</var> for

  1887. native system headers rather than the default <samp>/usr/include</samp>.

  1888. </p>

  1889. </dd>

  1890. <dt><code>--with-headers</code></dt>

  1891. <dt><code>--with-headers=<var>dir</var></code></dt>

  1892. <dd><p>Deprecated in favor of <samp>--with-sysroot</samp>.

  1893. Specifies that target headers are available when building a cross compiler.

  1894. The <var>dir</var> argument specifies a directory which has the target include

  1895. files.  These include files will be copied into the <samp>gcc</samp> install

  1896. directory.  <em>This option with the <var>dir</var> argument is required</em> when

  1897. building a cross compiler, if <samp><var>prefix</var>/<var>target</var>/sys-include</samp>

  1898. doesn&rsquo;t pre-exist.  If <samp><var>prefix</var>/<var>target</var>/sys-include</samp> does

  1899. pre-exist, the <var>dir</var> argument may be omitted.  <code>fixincludes</code>

  1900. will be run on these files to make them compatible with GCC.

  1901. </p>

  1902. </dd>

  1903. <dt><code>--without-headers</code></dt>

  1904. <dd><p>Tells GCC not use any target headers from a libc when building a cross

  1905. compiler.  When crossing to GNU/Linux, you need the headers so GCC

  1906. can build the exception handling for libgcc.

  1907. </p>

  1908. </dd>

  1909. <dt><code>--with-libs</code></dt>

  1910. <dt><code>--with-libs=&quot;<var>dir1</var> <var>dir2</var> &hellip; <var>dirN</var>&quot;</code></dt>

  1911. <dd><p>Deprecated in favor of <samp>--with-sysroot</samp>.

  1912. Specifies a list of directories which contain the target runtime

  1913. libraries.  These libraries will be copied into the <samp>gcc</samp> install

  1914. directory.  If the directory list is omitted, this option has no

  1915. effect.

  1916. </p>

  1917. </dd>

  1918. <dt><code>--with-newlib</code></dt>

  1919. <dd><p>Specifies that &lsquo;<samp>newlib</samp>&rsquo; is

  1920. being used as the target C library.  This causes <code>__eprintf</code> to be

  1921. omitted from <samp>libgcc.a</samp> on the assumption that it will be provided by

  1922. &lsquo;<samp>newlib</samp>&rsquo;.

  1923. </p>

  1924. <a name="avr"></a>

  1925. </dd>

  1926. <dt><code>--with-avrlibc</code></dt>

  1927. <dd><p>Only supported for the AVR target. Specifies that &lsquo;<samp>AVR-Libc</samp>&rsquo; is

  1928. being used as the target C&nbsp; library.  This causes float support

  1929. functions like <code>__addsf3</code> to be omitted from <samp>libgcc.a</samp> on

  1930. the assumption that it will be provided by <samp>libm.a</samp>.  For more

  1931. technical details, cf. <a href="http://gcc.gnu.org/PR54461">PR54461</a>.

  1932. It is not supported for

  1933. RTEMS configurations, which currently use newlib.  The option is

  1934. supported since version 4.7.2 and is the default in 4.8.0 and newer.

  1935. </p>

  1936. </dd>

  1937. <dt><code>--with-double={32|64|32,64|64,32}</code></dt>

  1938. <dt><code>--with-long-double={32|64|32,64|64,32|double}</code></dt>

  1939. <dd><p>Only supported for the AVR target since version&nbsp;10.

  1940. Specify the default layout available for the C/C++ &lsquo;<samp>double</samp>&rsquo;

  1941. and &lsquo;<samp>long double</samp>&rsquo; type, respectively. The following rules apply:

  1942. </p><ul>

  1943. <li> The first value after the &lsquo;<samp>=</samp>&rsquo; specifies the default layout (in bits)

  1944. of the type and also the default for the <samp>-mdouble=</samp> resp.

  1945. <samp>-mlong-double=</samp> compiler option.

  1946. </li><li> If more than one value is specified, respective multilib variants are

  1947. available, and  <samp>-mdouble=</samp> resp. <samp>-mlong-double=</samp> acts

  1948. as a multilib option.

  1949. </li><li> If <samp>--with-long-double=double</samp> is specified, &lsquo;<samp>double</samp>&rsquo; and

  1950. &lsquo;<samp>long double</samp>&rsquo; will have the same layout.

  1951. </li><li> The defaults are <samp>--with-long-double=64,32</samp> and

  1952. <samp>--with-double=32,64</samp>.  The default &lsquo;<samp>double</samp>&rsquo; layout imposed by

  1953. the latter is compatible with older versions of the compiler that implement

  1954. &lsquo;<samp>double</samp>&rsquo; as a 32-bit type, which does not comply to the language standard.

  1955. </li></ul>

  1956. <p>Not all combinations of <samp>--with-double=</samp> and

  1957. <samp>--with-long-double=</samp> are valid.  For example, the combination

  1958. <samp>--with-double=32,64</samp> <samp>--with-long-double=32</samp> will be

  1959. rejected because the first option specifies the availability of

  1960. multilibs for &lsquo;<samp>double</samp>&rsquo;, whereas the second option implies

  1961. that &lsquo;<samp>long double</samp>&rsquo; &mdash; and hence also &lsquo;<samp>double</samp>&rsquo; &mdash; is always

  1962. 32&nbsp;bits wide.

  1963. </p>

  1964. </dd>

  1965. <dt><code>--with-double-comparison={tristate|bool|libf7}</code></dt>

  1966. <dd><p>Only supported for the AVR target since version&nbsp;10.

  1967. Specify what result format is returned by library functions that

  1968. compare 64-bit floating point values (<code>DFmode</code>).

  1969. The GCC default is &lsquo;<samp>tristate</samp>&rsquo;.  If the floating point

  1970. implementation returns a boolean instead, set it to &lsquo;<samp>bool</samp>&rsquo;.

  1971. </p>

  1972. </dd>

  1973. <dt><code>--with-libf7={libgcc|math|math-symbols|no}</code></dt>

  1974. <dd><p>Only supported for the AVR target since version&nbsp;10.

  1975. Specify to which degree code from LibF7 is included in libgcc.

  1976. LibF7 is an ad-hoc, AVR-specific, 64-bit floating point emulation

  1977. written in C and (inline) assembly. &lsquo;<samp>libgcc</samp>&rsquo; adds support

  1978. for functions that one would usually expect in libgcc like double addition,

  1979. double comparisons and double conversions. &lsquo;<samp>math</samp>&rsquo; also adds routines

  1980. that one would expect in <samp>libm.a</samp>, but with <code>__</code> (two underscores)

  1981. prepended to the symbol names as specified by <samp>math.h</samp>.

  1982. &lsquo;<samp>math-symbols</samp>&rsquo; also defines weak aliases for the functions

  1983. declared in <samp>math.h</samp>.  However, <code>--with-libf7</code> won&rsquo;t

  1984. install no <samp>math.h</samp> header file whatsoever, this file must come

  1985. from elsewhere.  This option sets <samp>--with-double-comparison</samp>

  1986. to &lsquo;<samp>bool</samp>&rsquo;.

  1987. </p>

  1988. </dd>

  1989. <dt><code>--with-nds32-lib=<var>library</var></code></dt>

  1990. <dd><p>Specifies that <var>library</var> setting is used for building <samp>libgcc.a</samp>.

  1991. Currently, the valid <var>library</var> is &lsquo;<samp>newlib</samp>&rsquo; or &lsquo;<samp>mculib</samp>&rsquo;.

  1992. This option is only supported for the NDS32 target.

  1993. </p>

  1994. </dd>

  1995. <dt><code>--with-build-time-tools=<var>dir</var></code></dt>

  1996. <dd><p>Specifies where to find the set of target tools (assembler, linker, etc.)

  1997. that will be used while building GCC itself.  This option can be useful

  1998. if the directory layouts are different between the system you are building

  1999. GCC on, and the system where you will deploy it.

  2000. </p>

  2001. <p>For example, on an &lsquo;<samp>ia64-hp-hpux</samp>&rsquo; system, you may have the GNU

  2002. assembler and linker in <samp>/usr/bin</samp>, and the native tools in a

  2003. different path, and build a toolchain that expects to find the

  2004. native tools in <samp>/usr/bin</samp>.

  2005. </p>

  2006. <p>When you use this option, you should ensure that <var>dir</var> includes

  2007. <code>ar</code>, <code>as</code>, <code>ld</code>, <code>nm</code>,

  2008. <code>ranlib</code> and <code>strip</code> if necessary, and possibly

  2009. <code>objdump</code>.  Otherwise, GCC may use an inconsistent set of

  2010. tools.

  2011. </p></dd>

  2012. </dl>

  2013. 

  2014. <a name="Overriding-configure-test-results"></a>

  2015. <h4 class="subsubheading">Overriding <code>configure</code> test results</h4>

  2016. 

  2017. <p>Sometimes, it might be necessary to override the result of some

  2018. <code>configure</code> test, for example in order to ease porting to a new

  2019. system or work around a bug in a test.  The toplevel <code>configure</code>

  2020. script provides three variables for this:

  2021. </p>

  2022. <dl compact="compact">

  2023. <dt><code>build_configargs</code></dt>

  2024. <dd><a name="index-build_005fconfigargs"></a>

  2025. <p>The contents of this variable is passed to all build <code>configure</code>

  2026. scripts.

  2027. </p>

  2028. </dd>

  2029. <dt><code>host_configargs</code></dt>

  2030. <dd><a name="index-host_005fconfigargs"></a>

  2031. <p>The contents of this variable is passed to all host <code>configure</code>

  2032. scripts.

  2033. </p>

  2034. </dd>

  2035. <dt><code>target_configargs</code></dt>

  2036. <dd><a name="index-target_005fconfigargs"></a>

  2037. <p>The contents of this variable is passed to all target <code>configure</code>

  2038. scripts.

  2039. </p>

  2040. </dd>

  2041. </dl>

  2042. 

  2043. <p>In order to avoid shell and <code>make</code> quoting issues for complex

  2044. overrides, you can pass a setting for <code>CONFIG_SITE</code> and set

  2045. variables in the site file.

  2046. </p>

  2047. <a name="Objective-C-Specific-Options"></a>

  2048. <h4 class="subheading">Objective-C-Specific Options</h4>

  2049. 

  2050. <p>The following options apply to the build of the Objective-C runtime library.

  2051. </p>

  2052. <dl compact="compact">

  2053. <dt><code>--enable-objc-gc</code></dt>

  2054. <dd><p>Specify that an additional variant of the GNU Objective-C runtime library

  2055. is built, using an external build of the Boehm-Demers-Weiser garbage

  2056. collector (<a href="https://www.hboehm.info/gc/">https://www.hboehm.info/gc/</a>).  This library needs to be

  2057. available for each multilib variant, unless configured with

  2058. <samp>--enable-objc-gc=&lsquo;<samp>auto</samp>&rsquo;</samp> in which case the build of the

  2059. additional runtime library is skipped when not available and the build

  2060. continues.

  2061. </p>

  2062. </dd>

  2063. <dt><code>--with-target-bdw-gc=<var>list</var></code></dt>

  2064. <dt><code>--with-target-bdw-gc-include=<var>list</var></code></dt>

  2065. <dt><code>--with-target-bdw-gc-lib=<var>list</var></code></dt>

  2066. <dd><p>Specify search directories for the garbage collector header files and

  2067. libraries. <var>list</var> is a comma separated list of key value pairs of the

  2068. form &lsquo;<samp><var>multilibdir</var>=<var>path</var></samp>&rsquo;, where the default multilib key

  2069. is named as &lsquo;<samp>.</samp>&rsquo; (dot), or is omitted (e.g.

  2070. &lsquo;<samp>--with-target-bdw-gc=/opt/bdw-gc,32=/opt-bdw-gc32</samp>&rsquo;).

  2071. </p>

  2072. <p>The options <samp>--with-target-bdw-gc-include</samp> and

  2073. <samp>--with-target-bdw-gc-lib</samp> must always be specified together

  2074. for each multilib variant and they take precedence over

  2075. <samp>--with-target-bdw-gc</samp>.  If <samp>--with-target-bdw-gc-include</samp>

  2076. is missing values for a multilib, then the value for the default

  2077. multilib is used (e.g. &lsquo;<samp>--with-target-bdw-gc-include=/opt/bdw-gc/include</samp>&rsquo;

  2078. &lsquo;<samp>--with-target-bdw-gc-lib=/opt/bdw-gc/lib64,32=/opt-bdw-gc/lib32</samp>&rsquo;).

  2079. If none of these options are specified, the library is assumed in

  2080. default locations.

  2081. </p></dd>

  2082. </dl>

  2083. 

  2084. <a name="D-Specific-Options"></a>

  2085. <h4 class="subheading">D-Specific Options</h4>

  2086. 

  2087. <p>The following options apply to the build of the D runtime library.

  2088. </p>

  2089. <dl compact="compact">

  2090. <dt><code>--enable-libphobos-checking</code></dt>

  2091. <dt><code>--disable-libphobos-checking</code></dt>

  2092. <dt><code>--enable-libphobos-checking=<var>list</var></code></dt>

  2093. <dd><p>This option controls whether run-time checks and contracts are compiled into

  2094. the D runtime library.  When the option is not specified, the library is built

  2095. with &lsquo;<samp>release</samp>&rsquo; checking.  When the option is specified without a

  2096. <var>list</var>, the result is the same as &lsquo;<samp>--enable-libphobos-checking=yes</samp>&rsquo;.

  2097. Likewise, &lsquo;<samp>--disable-libphobos-checking</samp>&rsquo; is equivalent to

  2098. &lsquo;<samp>--enable-libphobos-checking=no</samp>&rsquo;.

  2099. </p>

  2100. <p>The categories of checks available in <var>list</var> are &lsquo;<samp>yes</samp>&rsquo; (compiles

  2101. libphobos with <samp>-fno-release</samp>), &lsquo;<samp>no</samp>&rsquo; (compiles libphobos with

  2102. <samp>-frelease</samp>), &lsquo;<samp>all</samp>&rsquo; (same as &lsquo;<samp>yes</samp>&rsquo;), &lsquo;<samp>none</samp>&rsquo; or

  2103. &lsquo;<samp>release</samp>&rsquo; (same as &lsquo;<samp>no</samp>&rsquo;).

  2104. </p>

  2105. <p>Individual checks available in <var>list</var> are &lsquo;<samp>assert</samp>&rsquo; (compiles libphobos

  2106. with an extra option <samp>-fassert</samp>).

  2107. </p>

  2108. </dd>

  2109. <dt><code>--with-libphobos-druntime-only</code></dt>

  2110. <dt><code>--with-libphobos-druntime-only=<var>choice</var></code></dt>

  2111. <dd><p>Specify whether to build only the core D runtime library (druntime), or both

  2112. the core and standard library (phobos) into libphobos.  This is useful for

  2113. targets that have full support in druntime, but no or incomplete support

  2114. in phobos.  <var>choice</var> can be one of &lsquo;<samp>auto</samp>&rsquo;, &lsquo;<samp>yes</samp>&rsquo;, and &lsquo;<samp>no</samp>&rsquo;

  2115. where &lsquo;<samp>auto</samp>&rsquo; is the default.

  2116. </p>

  2117. <p>When the option is not specified, the default choice &lsquo;<samp>auto</samp>&rsquo; means that it

  2118. is inferred whether the target has support for the phobos standard library.

  2119. When the option is specified without a <var>choice</var>,  the result is the same as

  2120. &lsquo;<samp>--with-libphobos-druntime-only=yes</samp>&rsquo;.

  2121. </p>

  2122. </dd>

  2123. <dt><code>--with-target-system-zlib</code></dt>

  2124. <dd><p>Use installed &lsquo;<samp>zlib</samp>&rsquo; rather than that included with GCC.  This needs

  2125. to be available for each multilib variant, unless configured with

  2126. <samp>--with-target-system-zlib=&lsquo;<samp>auto</samp>&rsquo;</samp> in which case the GCC&nbsp;included

  2127. &lsquo;<samp>zlib</samp>&rsquo; is only used when the system installed library is not available.

  2128. </p></dd>

  2129. </dl>

  2130. 

  2131. <hr />

  2132. <p>

  2133. <p><a href="./index.html">Return to the GCC Installation page</a>

  2134. </p>

  2135. 

  2136. 

  2137. 

  2138. 

  2139. 

  2140. 

  2141. 

  2142. 

  2143. 

  2144. 

  2145. 

  2146. </body>

  2147. </html>