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1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- Copyright (C) 1988-2020 Free Software Foundation, Inc. 4 5Permission is granted to copy, distribute and/or modify this document 6under the terms of the GNU Free Documentation License, Version 1.3 or 7any later version published by the Free Software Foundation; with no 8Invariant Sections, the Front-Cover texts being (a) (see below), and 9with the Back-Cover Texts being (b) (see below). A copy of the 10license is included in the section entitled "GNU 11Free Documentation License". 12 13(a) The FSF's Front-Cover Text is: 14 15A GNU Manual 16 17(b) The FSF's Back-Cover Text is: 18 19You have freedom to copy and modify this GNU Manual, like GNU 20 software. Copies published by the Free Software Foundation raise 21 funds for GNU development. --> 22<!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ --> 23<head> 24<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 25<title>Installing GCC: Configuration</title> 26 27<meta name="description" content="Installing GCC: Configuration"> 28<meta name="keywords" content="Installing GCC: Configuration"> 29<meta name="resource-type" content="document"> 30<meta name="distribution" content="global"> 31<meta name="Generator" content="makeinfo"> 32<style type="text/css"> 33<!-- 34a.summary-letter {text-decoration: none} 35blockquote.indentedblock {margin-right: 0em} 36blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} 37blockquote.smallquotation {font-size: smaller} 38div.display {margin-left: 3.2em} 39div.example {margin-left: 3.2em} 40div.lisp {margin-left: 3.2em} 41div.smalldisplay {margin-left: 3.2em} 42div.smallexample {margin-left: 3.2em} 43div.smalllisp {margin-left: 3.2em} 44kbd {font-style: oblique} 45pre.display {font-family: inherit} 46pre.format {font-family: inherit} 47pre.menu-comment {font-family: serif} 48pre.menu-preformatted {font-family: serif} 49pre.smalldisplay {font-family: inherit; font-size: smaller} 50pre.smallexample {font-size: smaller} 51pre.smallformat {font-family: inherit; font-size: smaller} 52pre.smalllisp {font-size: smaller} 53span.nolinebreak {white-space: nowrap} 54span.roman {font-family: initial; font-weight: normal} 55span.sansserif {font-family: sans-serif; font-weight: normal} 56ul.no-bullet {list-style: none} 57--> 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. 88This document describes the recommended configuration procedure 89for both native and cross targets. 90</p> 91<p>We use <var>srcdir</var> to refer to the toplevel source directory for 92GCC; 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> 95must 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> 97subdirectory, otherwise the build will fail. 98</p> 99<p>If either <var>srcdir</var> or <var>objdir</var> is located on an automounted NFS 100file system, the shell’s built-in <code>pwd</code> command will return 101temporary pathnames. Using these can lead to various sorts of build 102problems. To avoid this issue, set the <code>PWDCMD</code> environment 103variable to an automounter-aware <code>pwd</code> command, e.g., 104<code>pawd</code> or ‘<samp>amq -w</samp>’, during the configuration and build 105phases. 106</p> 107<p>First, we <strong>highly</strong> recommend that GCC be built into a 108separate directory from the sources which does <strong>not</strong> reside 109within the source tree. This is how we generally build GCC; building 110where <var>srcdir</var> == <var>objdir</var> should still work, but doesn’t 111get extensive testing; building where <var>objdir</var> is a subdirectory 112of <var>srcdir</var> is unsupported. 113</p> 114<p>If you have previously built GCC in the same directory for a 115different target machine, do ‘<samp>make distclean</samp>’ to delete all files 116that might be invalid. One of the files this deletes is <samp>Makefile</samp>; 117if ‘<samp>make distclean</samp>’ complains that <samp>Makefile</samp> does not exist 118or issues a message like “don’t know how to make distclean” it probably 119means that the directory is already suitably clean. However, with the 120recommended method of building in a separate <var>objdir</var>, you should 121simply 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 125your environment before running configure. Otherwise the configuration 126scripts 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 141to the source code, you should use the options described in this 142section 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 147to include a build number or build date. This version string will be 148included in the output of <code>gcc --version</code>. This suffix does 149not replace the default version string, only the ‘<samp>GCC</samp>’ part. 150</p> 151<p>The default value is ‘<samp>GCC</samp>’. 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. 156You are of course welcome to forward bugs reported to you to the FSF, 157if you determine that they are not bugs in your modifications. 158</p> 159<p>The default value refers to the FSF’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> 164should 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 171releases like <code>gcc-<var>version</var>/changes.html</code>. 172The <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> 183for nearly all native systems. Therefore, we highly recommend you do 184not 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> 187when configuring a cross compiler; examples of valid targets would be 188m68k-elf, sh-elf, etc. 189 190</li><li> Specifying just <var>target</var> instead of <samp>--target=<var>target</var></samp> 191implies 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 199GCC. A list of supported <var>options</var> follows; ‘<samp>configure 200--help</samp>’ may list other options, but those not listed below may not 201work 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 205corresponding <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 210directory. This is the recommended way to install the tools into a directory 211other 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 215subdirectory of <var>objdir</var> or vice versa. If specifying a directory 216beneath a user’s home directory tree, some shells will not expand 217<var>dirname</var> correctly if it contains the ‘<samp>~</samp>’ metacharacter; use 218<code>$HOME</code> instead. 219</p> 220<p>The following standard <code>autoconf</code> options are supported. Normally you 221should 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 225files. 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 236internal 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. 241The 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 246default 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 251data 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. 256The 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 261data 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 266than 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. 271The 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. 276The 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 282from the full GCC manuals, which are provided in Texinfo format. The manpages 283are derived by an automatic conversion process from parts of the full 284manual.) 285</p> 286</dd> 287<dt><code>--with-gxx-include-dir=<var>dirname</var></code></dt> 288<dd><p>Specify 289the installation directory for G++ header files. The default depends 290on other configuration options, and differs between cross and native 291configurations. 292</p> 293</dd> 294<dt><code>--with-specs=<var>specs</var></code></dt> 295<dd><p>Specify additional command line driver SPECS. 296This can be useful if you need to turn on a non-standard feature by 297default without modifying the compiler’s source code, for instance 298<samp>--with-specs=%{!fcommon:%{!fno-common:-fno-common}}</samp>. 299See “Spec Files” 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 307installing them. This option prepends <var>prefix</var> to the names of 308programs to install in <var>bindir</var> (see above). For example, specifying 309<samp>--program-prefix=foo-</samp> would result in ‘<samp>gcc</samp>’ 310being 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> 316would result in ‘<samp>gcc</samp>’ 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 ‘<samp>sed</samp>’ script <var>pattern</var> to be applied to the names 322of programs to install in <var>bindir</var> (see above). <var>pattern</var> has to 323consist of one or more basic ‘<samp>sed</samp>’ editing commands, separated by 324semicolons. For example, if you want the ‘<samp>gcc</samp>’ program name to be 325transformed to the installed program <samp>/usr/local/bin/myowngcc</samp> and 326the ‘<samp>g++</samp>’ program name to be transformed to 327<samp>/usr/local/bin/gspecial++</samp> without changing other program names, 328you could use the pattern 329<samp>--program-transform-name='s/^gcc$/myowngcc/; s/^g++$/gspecial++/'</samp> 330to achieve this effect. 331</p> 332<p>All three options can be combined and used together, resulting in more 333complex conversion patterns. As a basic rule, <var>prefix</var> (and 334<var>suffix</var>) are prepended (appended) before further transformations 335can happen with a special transformation script <var>pattern</var>. 336</p> 337<p>As currently implemented, this option only takes effect for native 338builds; cross compiler binaries’ names are not transformed even when a 339transformation is explicitly asked for by one of these options. 340</p> 341<p>For native builds, some of the installed programs are also installed 342with the target alias in front of their name, as in 343‘<samp>i686-pc-linux-gnu-gcc</samp>’. All of the above transformations happen 344before the target alias is prepended to the name—so, specifying 345<samp>--program-prefix=foo-</samp> and <samp>program-suffix=-3.1</samp>, the 346resulting 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 350transformed 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 355installation directory for local include files. The default is 356<samp>/usr/local</samp>. Specify this option if you want the compiler to 357search directory <samp><var>dirname</var>/include</samp> for locally installed 358header 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 361site has a different convention (not <samp>/usr/local</samp>) for where to put 362site-specific files. 363</p> 364<p>The default value for <samp>--with-local-prefix</samp> is <samp>/usr/local</samp> 365regardless of the value of <samp>--prefix</samp>. Specifying 366<samp>--prefix</samp> has no effect on which directory GCC searches for 367local header files. This may seem counterintuitive, but actually it is 368logical. 369</p> 370<p>The purpose of <samp>--prefix</samp> is to specify where to <em>install 371GCC</em>. The local header files in <samp>/usr/local/include</samp>—if you put 372any in that directory—are not part of GCC. They are part of other 373programs—perhaps many others. (GCC installs its own header files in 374another 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 377directory are part of GCC’s “system include” directories. Although these 378two directories are not fixed, they need to be searched in the proper 379order for the correct processing of the include_next directive. The 380local-prefix include directory is searched before the GCC-prefix 381include directory. Another characteristic of system include directories 382is 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 385compiler command line, to ensure that directories containing installed 386packages’ headers are searched. When <var>directory</var> is one of GCC’s 387system include directories, GCC will ignore the option so that system 388directories continue to be processed in the correct order. This 389may result in a search order different from what was specified but the 390directory 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 394used for both GCC and packages, GCC will automatically search for 395both headers and libraries. This provides a configuration that is 396easy to use. GCC behaves in a manner similar to that when it is 397installed 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 400use 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 403into a single directory, but it may be simpler to use different prefixes 404and the <samp>--with-local-prefix</samp> option to specify the location of the 405site-specific files for each version. It will then be necessary for 406users 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 411to 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>! 414The directory you use for <samp>--with-local-prefix</samp> <strong>must not</strong> 415contain any of the system’s standard header files. If it did contain 416them, certain programs would be miscompiled (including GNU Emacs, on 417certain targets), because this would override and nullify the header 418file 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 421ideas of what it is for. People use it as if it specified where to 422install part of GCC. Perhaps they make this assumption because 423installing 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 433header files, rather than <samp>/usr/include</samp>. This option is most useful 434if you are creating a compiler that should be isolated from the system 435as 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>[,…]]</code></dt> 441<dd><p>Build shared versions of libraries, if shared libraries are supported on 442the target platform. Unlike GCC 2.95.x and earlier, shared libraries 443are 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 446only for the listed packages. For other packages, only static libraries 447will be built. Package names currently recognized in the GCC tree are 448‘<samp>libgcc</samp>’ (also known as ‘<samp>gcc</samp>’), ‘<samp>libstdc++</samp>’ (not 449‘<samp>libstdc++-v3</samp>’), ‘<samp>libffi</samp>’, ‘<samp>zlib</samp>’, ‘<samp>boehm-gc</samp>’, 450‘<samp>ada</samp>’, ‘<samp>libada</samp>’, ‘<samp>libgo</samp>’, ‘<samp>libobjc</samp>’, and ‘<samp>libphobos</samp>’. 451Note ‘<samp>libiberty</samp>’ 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 455argument, only <samp>--enable-shared</samp> does. 456</p> 457<p>Contrast with <samp>--enable-host-shared</samp>, which affects <em>host</em> 458code. 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 463machine code (with -fPIC), allowing it to be used within shared libraries, 464but 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> 469libraries. 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 474assembler it finds is the GNU assembler. However, this does not modify 475the rules to find an assembler and will result in confusion if the 476assembler found is not actually the GNU assembler. (Confusion may also 477result if the compiler finds the GNU assembler but has not been 478configured with <samp>--with-gnu-as</samp>.) If you have more than one 479assembler installed on your system, you may want to use this option in 480connection 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 484whether you use the GNU assembler. On any other system, 485<samp>--with-gnu-as</samp> has no effect. 486</p> 487<ul> 488<li> ‘<samp>hppa1.0-<var>any</var>-<var>any</var></samp>’ 489</li><li> ‘<samp>hppa1.1-<var>any</var>-<var>any</var></samp>’ 490</li><li> ‘<samp>sparc-sun-solaris2.<var>any</var></samp>’ 491</li><li> ‘<samp>sparc64-<var>any</var>-solaris2.<var>any</var></samp>’ 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 498an 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 504defaults to <samp>/usr/local</samp> unless overridden by the 505<samp>--prefix=<var>pathname</var></samp> switch described above. <var>target</var> 506is the target system triple, such as ‘<samp>sparc-sun-solaris2.7</samp>’, 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 510operating system specific directories (e.g. <samp>/usr/ccs/bin</samp> on 511Solaris 2). 512 513</li><li> Check in the <code>PATH</code> for a tool whose name is prefixed by the 514target system triple. 515 516</li><li> Check in the <code>PATH</code> for a tool whose name is not prefixed by the 517target system triple, if the host and target system triple are 518the same (in other words, we use a host tool if it can be used for 519the target as well). 520</li></ul> 521 522<p>You may want to use <samp>--with-as</samp> if no assembler 523is installed in the directories listed above, or if you have multiple 524assemblers installed and want to choose one that is not found by the 525above 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> 530but 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> 535but for the linker. 536</p> 537</dd> 538<dt><code>--with-dsymutil=<var>pathname</var></code></dt> 539<dd><p>Same as <a href="#with-as"><samp>--with-as</samp></a> 540but for the debug linker (only used on Darwin platforms so far). 541</p> 542</dd> 543<dt><code>--with-stabs</code></dt> 544<dd><p>Specify that stabs debugging 545information should be used instead of whatever format the host normally 546uses. Normally GCC uses the same debug format as the host system. 547</p> 548</dd> 549<dt><code>--with-tls=<var>dialect</var></code></dt> 550<dd><p>Specify the default TLS dialect, for systems were there is a choice. 551For ARM targets, possible values for <var>dialect</var> are <code>gnu</code> or 552<code>gnu2</code>, which select between the original GNU dialect and the GNU TLS 553descriptor-based dialect. 554</p> 555</dd> 556<dt><code>--enable-multiarch</code></dt> 557<dd><p>Specify whether to enable or disable multiarch support. The default is 558to check for glibc start files in a multiarch location, and enable it 559if the files are found. The auto detection is enabled for native builds, 560and for cross builds configured with <samp>--with-sysroot</samp>, and without 561<samp>--with-native-system-header-dir</samp>. 562More documentation about multiarch can be found at 563<a href="https://wiki.debian.org/Multiarch">https://wiki.debian.org/Multiarch</a>. 564</p> 565</dd> 566<dt><code>--enable-sjlj-exceptions</code></dt> 567<dd><p>Force use of the <code>setjmp</code>/<code>longjmp</code>-based scheme for exceptions. 568‘<samp>configure</samp>’ ordinarily picks the correct value based on the platform. 569Only use this option if you are sure you need a different setting. 570</p> 571</dd> 572<dt><code>--enable-vtable-verify</code></dt> 573<dd><p>Specify whether to enable or disable the vtable verification feature. 574Enabling this feature causes libstdc++ to be built with its virtual calls 575in verifiable mode. This means that, when linked with libvtv, every 576virtual call in libstdc++ will verify the vtable pointer through which the 577call will be made before actually making the call. If not linked with libvtv, 578the verifier will call stub functions (in libstdc++ itself) and do nothing. 579If vtable verification is disabled, then libstdc++ is not built with its 580virtual calls in verifiable mode at all. However the libvtv library will 581still be built (see <samp>--disable-libvtv</samp> to turn off building libvtv). 582<samp>--disable-vtable-verify</samp> is the default. 583</p> 584</dd> 585<dt><code>--disable-gcov</code></dt> 586<dd><p>Specify that the run-time library used for coverage analysis 587and associated host tools should not be built. 588</p> 589</dd> 590<dt><code>--disable-multilib</code></dt> 591<dd><p>Specify that multiple target 592libraries to support different target variants, calling 593conventions, etc. should not be built. The default is to build a 594predefined set of them. 595</p> 596<p>Some targets provide finer-grained control over which multilibs are built 597(e.g., <samp>--disable-softfloat</samp>): 598</p><dl compact="compact"> 599<dt><code>arm-*-*</code></dt> 600<dd><p>fpu, 26bit, underscore, interwork, biendian, nofmult. 601</p> 602</dd> 603<dt><code>m68*-*-*</code></dt> 604<dd><p>softfloat, m68881, m68000, m68020. 605</p> 606</dd> 607<dt><code>mips*-*-*</code></dt> 608<dd><p>single-float, biendian, softfloat. 609</p> 610</dd> 611<dt><code>msp430-*-*</code></dt> 612<dd><p>no-exceptions 613</p> 614</dd> 615<dt><code>powerpc*-*-*, rs6000*-*-*</code></dt> 616<dd><p>aix64, pthread, softfloat, powercpu, powerpccpu, powerpcos, biendian, 617sysv, aix. 618</p> 619</dd> 620</dl> 621 622</dd> 623<dt><code>--with-multilib-list=<var>list</var></code></dt> 624<dt><code>--without-multilib-list</code></dt> 625<dd><p>Specify what multilibs to build. <var>list</var> is a comma separated list of 626values, possibly consisting of a single value. Currently only implemented 627for aarch64*-*-*, arm*-*-*, riscv*-*-*, sh*-*-* and x86-64-*-linux*. The 628accepted values and meaning for each target is given below. 629</p> 630<dl compact="compact"> 631<dt><code>aarch64*-*-*</code></dt> 632<dd><p><var>list</var> is a comma separated list of <code>ilp32</code>, and <code>lp64</code> 633to enable ILP32 and LP64 run-time libraries, respectively. If 634<var>list</var> is empty, then there will be no multilibs and only the 635default run-time library will be built. If <var>list</var> is 636<code>default</code> or –with-multilib-list= is not specified, then the 637default set of libraries is selected based on the value of 638<samp>--target</samp>. 639</p> 640</dd> 641<dt><code>arm*-*-*</code></dt> 642<dd><p><var>list</var> is a comma separated list of <code>aprofile</code> and 643<code>rmprofile</code> to build multilibs for A or R and M architecture 644profiles respectively. Note that, due to some limitation of the current 645multilib framework, using the combined <code>aprofile,rmprofile</code> 646multilibs selects in some cases a less optimal multilib than when using 647the multilib profile for the architecture targetted. The special value 648<code>default</code> is also accepted and is equivalent to omitting the 649option, i.e., only the default run-time library will be enabled. 650</p> 651<p><var>list</var> may instead contain <code>@name</code>, to use the multilib 652configuration Makefile fragment <samp>name</samp> in <samp>gcc/config/arm</samp> in 653the source tree (it is part of the corresponding sources, after all). 654It is recommended, but not required, that files used for this purpose to 655be named starting with <samp>t-ml-</samp>, to make their intended purpose 656self-evident, in line with GCC conventions. Such files enable custom, 657user-chosen multilib lists to be configured. Whether multiple such 658files can be used together depends on the contents of the supplied 659files. See <samp>gcc/config/arm/t-multilib</samp> and its supplementary 660<samp>gcc/config/arm/t-*profile</samp> files for an example of what such 661Makefile fragments might look like for this version of GCC. The macros 662expected to be defined in these fragments are not stable across GCC 663releases, so make sure they define the <code>MULTILIB</code>-related macros 664expected by the version of GCC you are building. 665See “Target Makefile Fragments” in the internals manual. 666</p> 667<p>The table below gives the combination of ISAs, architectures, FPUs and 668floating-point ABIs for which multilibs are built for each predefined 669profile. The union of these options is considered when specifying both 670<code>aprofile</code> and <code>rmprofile</code>. 671</p> 672<table> 673<tr><td width="15%">Option</td><td width="28%">aprofile</td><td width="30%">rmprofile</td></tr> 674<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> 675<tr><td width="15%">Architectures<br><br><br><br><br><br></td><td width="28%">default architecture<br> 676<code>-march=armv7-a</code><br> 677<code>-march=armv7ve</code><br> 678<code>-march=armv8-a</code><br><br><br></td><td width="30%">default architecture<br> 679<code>-march=armv6s-m</code><br> 680<code>-march=armv7-m</code><br> 681<code>-march=armv7e-m</code><br> 682<code>-march=armv8-m.base</code><br> 683<code>-march=armv8-m.main</code><br> 684<code>-march=armv7</code></td></tr> 685<tr><td width="15%">FPUs<br><br><br><br><br></td><td width="28%">none<br> 686<code>-mfpu=vfpv3-d16</code><br> 687<code>-mfpu=neon</code><br> 688<code>-mfpu=vfpv4-d16</code><br> 689<code>-mfpu=neon-vfpv4</code><br> 690<code>-mfpu=neon-fp-armv8</code></td><td width="30%">none<br> 691<code>-mfpu=vfpv3-d16</code><br> 692<code>-mfpu=fpv4-sp-d16</code><br> 693<code>-mfpu=fpv5-sp-d16</code><br> 694<code>-mfpu=fpv5-d16</code><br></td></tr> 695<tr><td width="15%">floating-point ABIs<br><br></td><td width="28%"><code>-mfloat-abi=soft</code><br> 696<code>-mfloat-abi=softfp</code><br> 697<code>-mfloat-abi=hard</code></td><td width="30%"><code>-mfloat-abi=soft</code><br> 698<code>-mfloat-abi=softfp</code><br> 699<code>-mfloat-abi=hard</code></td></tr> 700</table> 701 702</dd> 703<dt><code>riscv*-*-*</code></dt> 704<dd><p><var>list</var> is a single ABI name. The target architecture must be either 705<code>rv32gc</code> or <code>rv64gc</code>. This will build a single multilib for the 706specified architecture and ABI pair. If <code>--with-multilib-list</code> is not 707given, then a default set of multilibs is selected based on the value of 708<samp>--target</samp>. This is usually a large set of multilibs. 709</p> 710</dd> 711<dt><code>sh*-*-*</code></dt> 712<dd><p><var>list</var> is a comma separated list of CPU names. These must be of the 713form <code>sh*</code> or <code>m*</code> (in which case they match the compiler option 714for that processor). The list should not contain any endian options - 715these are handled by <samp>--with-endian</samp>. 716</p> 717<p>If <var>list</var> is empty, then there will be no multilibs for extra 718processors. The multilib for the secondary endian remains enabled. 719</p> 720<p>As a special case, if an entry in the list starts with a <code>!</code> 721(exclamation point), then it is added to the list of excluded multilibs. 722Entries of this sort should be compatible with ‘<samp>MULTILIB_EXCLUDES</samp>’ 723(once the leading <code>!</code> has been stripped). 724</p> 725<p>If <samp>--with-multilib-list</samp> is not given, then a default set of 726multilibs is selected based on the value of <samp>--target</samp>. This is 727usually the complete set of libraries, but some targets imply a more 728specialized subset. 729</p> 730<p>Example 1: to configure a compiler for SH4A only, but supporting both 731endians, with little endian being the default: 732</p><div class="smallexample"> 733<pre class="smallexample">--with-cpu=sh4a --with-endian=little,big --with-multilib-list= 734</pre></div> 735 736<p>Example 2: to configure a compiler for both SH4A and SH4AL-DSP, but with 737only little endian SH4AL: 738</p><div class="smallexample"> 739<pre class="smallexample">--with-cpu=sh4a --with-endian=little,big \ 740--with-multilib-list=sh4al,!mb/m4al 741</pre></div> 742 743</dd> 744<dt><code>x86-64-*-linux*</code></dt> 745<dd><p><var>list</var> is a comma separated list of <code>m32</code>, <code>m64</code> and 746<code>mx32</code> to enable 32-bit, 64-bit and x32 run-time libraries, 747respectively. If <var>list</var> is empty, then there will be no multilibs 748and only the default run-time library will be enabled. 749</p> 750<p>If <samp>--with-multilib-list</samp> is not given, then only 32-bit and 75164-bit run-time libraries will be enabled. 752</p></dd> 753</dl> 754 755</dd> 756<dt><code>--with-endian=<var>endians</var></code></dt> 757<dd><p>Specify what endians to use. 758Currently only implemented for sh*-*-*. 759</p> 760<p><var>endians</var> may be one of the following: 761</p><dl compact="compact"> 762<dt><code>big</code></dt> 763<dd><p>Use big endian exclusively. 764</p></dd> 765<dt><code>little</code></dt> 766<dd><p>Use little endian exclusively. 767</p></dd> 768<dt><code>big,little</code></dt> 769<dd><p>Use big endian by default. Provide a multilib for little endian. 770</p></dd> 771<dt><code>little,big</code></dt> 772<dd><p>Use little endian by default. Provide a multilib for big endian. 773</p></dd> 774</dl> 775 776</dd> 777<dt><code>--enable-threads</code></dt> 778<dd><p>Specify that the target 779supports threads. This affects the Objective-C compiler and runtime 780library, and exception handling for other languages like C++. 781On some systems, this is the default. 782</p> 783<p>In general, the best (and, in many cases, the only known) threading 784model available will be configured for use. Beware that on some 785systems, GCC has not been taught what threading models are generally 786available for the system. In this case, <samp>--enable-threads</samp> is an 787alias for <samp>--enable-threads=single</samp>. 788</p> 789</dd> 790<dt><code>--disable-threads</code></dt> 791<dd><p>Specify that threading support should be disabled for the system. 792This is an alias for <samp>--enable-threads=single</samp>. 793</p> 794</dd> 795<dt><code>--enable-threads=<var>lib</var></code></dt> 796<dd><p>Specify that 797<var>lib</var> is the thread support library. This affects the Objective-C 798compiler and runtime library, and exception handling for other languages 799like C++. The possibilities for <var>lib</var> are: 800</p> 801<dl compact="compact"> 802<dt><code>aix</code></dt> 803<dd><p>AIX thread support. 804</p></dd> 805<dt><code>dce</code></dt> 806<dd><p>DCE thread support. 807</p></dd> 808<dt><code>lynx</code></dt> 809<dd><p>LynxOS thread support. 810</p></dd> 811<dt><code>mipssde</code></dt> 812<dd><p>MIPS SDE thread support. 813</p></dd> 814<dt><code>no</code></dt> 815<dd><p>This is an alias for ‘<samp>single</samp>’. 816</p></dd> 817<dt><code>posix</code></dt> 818<dd><p>Generic POSIX/Unix98 thread support. 819</p></dd> 820<dt><code>rtems</code></dt> 821<dd><p>RTEMS thread support. 822</p></dd> 823<dt><code>single</code></dt> 824<dd><p>Disable thread support, should work for all platforms. 825</p></dd> 826<dt><code>tpf</code></dt> 827<dd><p>TPF thread support. 828</p></dd> 829<dt><code>vxworks</code></dt> 830<dd><p>VxWorks thread support. 831</p></dd> 832<dt><code>win32</code></dt> 833<dd><p>Microsoft Win32 API thread support. 834</p></dd> 835</dl> 836 837</dd> 838<dt><code>--enable-tls</code></dt> 839<dd><p>Specify that the target supports TLS (Thread Local Storage). Usually 840configure can correctly determine if TLS is supported. In cases where 841it guesses incorrectly, TLS can be explicitly enabled or disabled with 842<samp>--enable-tls</samp> or <samp>--disable-tls</samp>. This can happen if 843the assembler supports TLS but the C library does not, or if the 844assumptions made by the configure test are incorrect. 845</p> 846</dd> 847<dt><code>--disable-tls</code></dt> 848<dd><p>Specify that the target does not support TLS. 849This is an alias for <samp>--enable-tls=no</samp>. 850</p> 851</dd> 852<dt><code>--disable-tm-clone-registry</code></dt> 853<dd><p>Disable TM clone registry in libgcc. It is enabled in libgcc by default. 854This option helps to reduce code size for embedded targets which do 855not use transactional memory. 856</p> 857</dd> 858<dt><code>--with-cpu=<var>cpu</var></code></dt> 859<dt><code>--with-cpu-32=<var>cpu</var></code></dt> 860<dt><code>--with-cpu-64=<var>cpu</var></code></dt> 861<dd><p>Specify which cpu variant the compiler should generate code for by default. 862<var>cpu</var> will be used as the default value of the <samp>-mcpu=</samp> switch. 863This option is only supported on some targets, including ARC, ARM, i386, M68k, 864PowerPC, and SPARC. It is mandatory for ARC. The <samp>--with-cpu-32</samp> and 865<samp>--with-cpu-64</samp> options specify separate default CPUs for 86632-bit and 64-bit modes; these options are only supported for aarch64, i386, 867x86-64, PowerPC, and SPARC. 868</p> 869</dd> 870<dt><code>--with-schedule=<var>cpu</var></code></dt> 871<dt><code>--with-arch=<var>cpu</var></code></dt> 872<dt><code>--with-arch-32=<var>cpu</var></code></dt> 873<dt><code>--with-arch-64=<var>cpu</var></code></dt> 874<dt><code>--with-tune=<var>cpu</var></code></dt> 875<dt><code>--with-tune-32=<var>cpu</var></code></dt> 876<dt><code>--with-tune-64=<var>cpu</var></code></dt> 877<dt><code>--with-abi=<var>abi</var></code></dt> 878<dt><code>--with-fpu=<var>type</var></code></dt> 879<dt><code>--with-float=<var>type</var></code></dt> 880<dd><p>These configure options provide default values for the <samp>-mschedule=</samp>, 881<samp>-march=</samp>, <samp>-mtune=</samp>, <samp>-mabi=</samp>, and <samp>-mfpu=</samp> 882options and for <samp>-mhard-float</samp> or <samp>-msoft-float</samp>. As with 883<samp>--with-cpu</samp>, which switches will be accepted and acceptable values 884of the arguments depend on the target. 885</p> 886</dd> 887<dt><code>--with-mode=<var>mode</var></code></dt> 888<dd><p>Specify if the compiler should default to <samp>-marm</samp> or <samp>-mthumb</samp>. 889This option is only supported on ARM targets. 890</p> 891</dd> 892<dt><code>--with-stack-offset=<var>num</var></code></dt> 893<dd><p>This option sets the default for the -mstack-offset=<var>num</var> option, 894and will thus generally also control the setting of this option for 895libraries. This option is only supported on Epiphany targets. 896</p> 897</dd> 898<dt><code>--with-fpmath=<var>isa</var></code></dt> 899<dd><p>This options sets <samp>-mfpmath=sse</samp> by default and specifies the default 900ISA for floating-point arithmetics. You can select either ‘<samp>sse</samp>’ which 901enables <samp>-msse2</samp> or ‘<samp>avx</samp>’ which enables <samp>-mavx</samp> by default. 902This option is only supported on i386 and x86-64 targets. 903</p> 904</dd> 905<dt><code>--with-fp-32=<var>mode</var></code></dt> 906<dd><p>On MIPS targets, set the default value for the <samp>-mfp</samp> option when using 907the o32 ABI. The possibilities for <var>mode</var> are: 908</p><dl compact="compact"> 909<dt><code>32</code></dt> 910<dd><p>Use the o32 FP32 ABI extension, as with the <samp>-mfp32</samp> command-line 911option. 912</p></dd> 913<dt><code>xx</code></dt> 914<dd><p>Use the o32 FPXX ABI extension, as with the <samp>-mfpxx</samp> command-line 915option. 916</p></dd> 917<dt><code>64</code></dt> 918<dd><p>Use the o32 FP64 ABI extension, as with the <samp>-mfp64</samp> command-line 919option. 920</p></dd> 921</dl> 922<p>In the absence of this configuration option the default is to use the o32 923FP32 ABI extension. 924</p> 925</dd> 926<dt><code>--with-odd-spreg-32</code></dt> 927<dd><p>On MIPS targets, set the <samp>-modd-spreg</samp> option by default when using 928the o32 ABI. 929</p> 930</dd> 931<dt><code>--without-odd-spreg-32</code></dt> 932<dd><p>On MIPS targets, set the <samp>-mno-odd-spreg</samp> option by default when using 933the o32 ABI. This is normally used in conjunction with 934<samp>--with-fp-32=64</samp> in order to target the o32 FP64A ABI extension. 935</p> 936</dd> 937<dt><code>--with-nan=<var>encoding</var></code></dt> 938<dd><p>On MIPS targets, set the default encoding convention to use for the 939special not-a-number (NaN) IEEE 754 floating-point data. The 940possibilities for <var>encoding</var> are: 941</p><dl compact="compact"> 942<dt><code>legacy</code></dt> 943<dd><p>Use the legacy encoding, as with the <samp>-mnan=legacy</samp> command-line 944option. 945</p></dd> 946<dt><code>2008</code></dt> 947<dd><p>Use the 754-2008 encoding, as with the <samp>-mnan=2008</samp> command-line 948option. 949</p></dd> 950</dl> 951<p>To use this configuration option you must have an assembler version 952installed that supports the <samp>-mnan=</samp> command-line option too. 953In the absence of this configuration option the default convention is 954the legacy encoding, as when neither of the <samp>-mnan=2008</samp> and 955<samp>-mnan=legacy</samp> command-line options has been used. 956</p> 957</dd> 958<dt><code>--with-divide=<var>type</var></code></dt> 959<dd><p>Specify how the compiler should generate code for checking for 960division by zero. This option is only supported on the MIPS target. 961The possibilities for <var>type</var> are: 962</p><dl compact="compact"> 963<dt><code>traps</code></dt> 964<dd><p>Division by zero checks use conditional traps (this is the default on 965systems that support conditional traps). 966</p></dd> 967<dt><code>breaks</code></dt> 968<dd><p>Division by zero checks use the break instruction. 969</p></dd> 970</dl> 971 972 973</dd> 974<dt><code>--with-llsc</code></dt> 975<dd><p>On MIPS targets, make <samp>-mllsc</samp> the default when no 976<samp>-mno-llsc</samp> option is passed. This is the default for 977Linux-based targets, as the kernel will emulate them if the ISA does 978not provide them. 979</p> 980</dd> 981<dt><code>--without-llsc</code></dt> 982<dd><p>On MIPS targets, make <samp>-mno-llsc</samp> the default when no 983<samp>-mllsc</samp> option is passed. 984</p> 985</dd> 986<dt><code>--with-synci</code></dt> 987<dd><p>On MIPS targets, make <samp>-msynci</samp> the default when no 988<samp>-mno-synci</samp> option is passed. 989</p> 990</dd> 991<dt><code>--without-synci</code></dt> 992<dd><p>On MIPS targets, make <samp>-mno-synci</samp> the default when no 993<samp>-msynci</samp> option is passed. This is the default. 994</p> 995</dd> 996<dt><code>--with-lxc1-sxc1</code></dt> 997<dd><p>On MIPS targets, make <samp>-mlxc1-sxc1</samp> the default when no 998<samp>-mno-lxc1-sxc1</samp> option is passed. This is the default. 999</p> 1000</dd> 1001<dt><code>--without-lxc1-sxc1</code></dt> 1002<dd><p>On MIPS targets, make <samp>-mno-lxc1-sxc1</samp> the default when no 1003<samp>-mlxc1-sxc1</samp> option is passed. The indexed load/store 1004instructions are not directly a problem but can lead to unexpected 1005behaviour when deployed in an application intended for a 32-bit address 1006space but run on a 64-bit processor. The issue is seen because all 1007known MIPS 64-bit Linux kernels execute o32 and n32 applications 1008with 64-bit addressing enabled which affects the overflow behaviour 1009of the indexed addressing mode. GCC will assume that ordinary 101032-bit arithmetic overflow behaviour is the same whether performed 1011as an <code>addu</code> instruction or as part of the address calculation 1012in <code>lwxc1</code> type instructions. This assumption holds true in a 1013pure 32-bit environment and can hold true in a 64-bit environment if 1014the address space is accurately set to be 32-bit for o32 and n32. 1015</p> 1016</dd> 1017<dt><code>--with-madd4</code></dt> 1018<dd><p>On MIPS targets, make <samp>-mmadd4</samp> the default when no 1019<samp>-mno-madd4</samp> option is passed. This is the default. 1020</p> 1021</dd> 1022<dt><code>--without-madd4</code></dt> 1023<dd><p>On MIPS targets, make <samp>-mno-madd4</samp> the default when no 1024<samp>-mmadd4</samp> option is passed. The <code>madd4</code> instruction 1025family can be problematic when targeting a combination of cores that 1026implement these instructions differently. There are two known cores 1027that implement these as fused operations instead of unfused (where 1028unfused is normally expected). Disabling these instructions is the 1029only way to ensure compatible code is generated; this will incur 1030a performance penalty. 1031</p> 1032</dd> 1033<dt><code>--with-mips-plt</code></dt> 1034<dd><p>On MIPS targets, make use of copy relocations and PLTs. 1035These features are extensions to the traditional 1036SVR4-based MIPS ABIs and require support from GNU binutils 1037and the runtime C library. 1038</p> 1039</dd> 1040<dt><code>--with-stack-clash-protection-guard-size=<var>size</var></code></dt> 1041<dd><p>On certain targets this option sets the default stack clash protection guard 1042size as a power of two in bytes. On AArch64 <var>size</var> is required to be either 104312 (4KB) or 16 (64KB). 1044</p> 1045</dd> 1046<dt><code>--enable-__cxa_atexit</code></dt> 1047<dd><p>Define if you want to use __cxa_atexit, rather than atexit, to 1048register C++ destructors for local statics and global objects. 1049This is essential for fully standards-compliant handling of 1050destructors, but requires __cxa_atexit in libc. This option is currently 1051only available on systems with GNU libc. When enabled, this will cause 1052<samp>-fuse-cxa-atexit</samp> to be passed by default. 1053</p> 1054</dd> 1055<dt><code>--enable-gnu-indirect-function</code></dt> 1056<dd><p>Define if you want to enable the <code>ifunc</code> attribute. This option is 1057currently only available on systems with GNU libc on certain targets. 1058</p> 1059</dd> 1060<dt><code>--enable-target-optspace</code></dt> 1061<dd><p>Specify that target 1062libraries should be optimized for code space instead of code speed. 1063This is the default for the m32r platform. 1064</p> 1065</dd> 1066<dt><code>--with-cpp-install-dir=<var>dirname</var></code></dt> 1067<dd><p>Specify that the user visible <code>cpp</code> program should be installed 1068in <samp><var>prefix</var>/<var>dirname</var>/cpp</samp>, in addition to <var>bindir</var>. 1069</p> 1070</dd> 1071<dt><code>--enable-comdat</code></dt> 1072<dd><p>Enable COMDAT group support. This is primarily used to override the 1073automatically detected value. 1074</p> 1075</dd> 1076<dt><code>--enable-initfini-array</code></dt> 1077<dd><p>Force the use of sections <code>.init_array</code> and <code>.fini_array</code> 1078(instead of <code>.init</code> and <code>.fini</code>) for constructors and 1079destructors. Option <samp>--disable-initfini-array</samp> has the 1080opposite effect. If neither option is specified, the configure script 1081will try to guess whether the <code>.init_array</code> and 1082<code>.fini_array</code> sections are supported and, if they are, use them. 1083</p> 1084</dd> 1085<dt><code>--enable-link-mutex</code></dt> 1086<dd><p>When building GCC, use a mutex to avoid linking the compilers for 1087multiple languages at the same time, to avoid thrashing on build 1088systems with limited free memory. The default is not to use such a mutex. 1089</p> 1090</dd> 1091<dt><code>--enable-maintainer-mode</code></dt> 1092<dd><p>The build rules that regenerate the Autoconf and Automake output files as 1093well as the GCC master message catalog <samp>gcc.pot</samp> are normally 1094disabled. This is because it can only be rebuilt if the complete source 1095tree is present. If you have changed the sources and want to rebuild the 1096catalog, configuring with <samp>--enable-maintainer-mode</samp> will enable 1097this. Note that you need a recent version of the <code>gettext</code> tools 1098to do so. 1099</p> 1100</dd> 1101<dt><code>--disable-bootstrap</code></dt> 1102<dd><p>For a native build, the default configuration is to perform 1103a 3-stage bootstrap of the compiler when ‘<samp>make</samp>’ is invoked, 1104testing that GCC can compile itself correctly. If you want to disable 1105this process, you can configure with <samp>--disable-bootstrap</samp>. 1106</p> 1107</dd> 1108<dt><code>--enable-bootstrap</code></dt> 1109<dd><p>In special cases, you may want to perform a 3-stage build 1110even if the target and host triplets are different. 1111This is possible when the host can run code compiled for 1112the target (e.g. host is i686-linux, target is i486-linux). 1113Starting from GCC 4.2, to do this you have to configure explicitly 1114with <samp>--enable-bootstrap</samp>. 1115</p> 1116</dd> 1117<dt><code>--enable-generated-files-in-srcdir</code></dt> 1118<dd><p>Neither the .c and .h files that are generated from Bison and flex nor the 1119info manuals and man pages that are built from the .texi files are present 1120in the repository development tree. When building GCC from that development tree, 1121or from one of our snapshots, those generated files are placed in your 1122build directory, which allows for the source to be in a readonly 1123directory. 1124</p> 1125<p>If you configure with <samp>--enable-generated-files-in-srcdir</samp> then those 1126generated files will go into the source directory. This is mainly intended 1127for generating release or prerelease tarballs of the GCC sources, since it 1128is not a requirement that the users of source releases to have flex, Bison, 1129or makeinfo. 1130</p> 1131</dd> 1132<dt><code>--enable-version-specific-runtime-libs</code></dt> 1133<dd><p>Specify 1134that runtime libraries should be installed in the compiler specific 1135subdirectory (<samp><var>libdir</var>/gcc</samp>) rather than the usual places. In 1136addition, ‘<samp>libstdc++</samp>’’s include files will be installed into 1137<samp><var>libdir</var></samp> unless you overruled it by using 1138<samp>--with-gxx-include-dir=<var>dirname</var></samp>. Using this option is 1139particularly useful if you intend to use several versions of GCC in 1140parallel. The default is ‘<samp>yes</samp>’ for ‘<samp>libada</samp>’, and ‘<samp>no</samp>’ for 1141the remaining libraries. 1142</p> 1143</dd> 1144<dt><code><a name="WithAixSoname"></a>--with-aix-soname=‘<samp>aix</samp>’, ‘<samp>svr4</samp>’ or ‘<samp>both</samp>’</code></dt> 1145<dd><p>Traditional AIX shared library versioning (versioned <code>Shared Object</code> 1146files as members of unversioned <code>Archive Library</code> files named 1147‘<samp>lib.a</samp>’) causes numerous headaches for package managers. However, 1148<code>Import Files</code> as members of <code>Archive Library</code> files allow for 1149<strong>filename-based versioning</strong> of shared libraries as seen on Linux/SVR4, 1150where this is called the "SONAME". But as they prevent static linking, 1151<code>Import Files</code> may be used with <code>Runtime Linking</code> only, where the 1152linker does search for ‘<samp>libNAME.so</samp>’ before ‘<samp>libNAME.a</samp>’ library 1153filenames with the ‘<samp>-lNAME</samp>’ linker flag. 1154</p> 1155<a name="AixLdCommand"></a><p>For detailed information please refer to the AIX 1156<a href="https://www.ibm.com/support/knowledgecenter/search/%22the%20ld%20command%2C%20also%20called%20the%20linkage%20editor%20or%20binder%22">ld 1157Command</a> reference. 1158</p> 1159<p>As long as shared library creation is enabled, upon: 1160</p><dl compact="compact"> 1161<dt><code>--with-aix-soname=aix</code></dt> 1162<dt><code>--with-aix-soname=both</code></dt> 1163<dd><p>A (traditional AIX) <code>Shared Archive Library</code> file is created: 1164 </p><ul> 1165<li> using the ‘<samp>libNAME.a</samp>’ filename scheme 1166 </li><li> with the <code>Shared Object</code> file as archive member named 1167 ‘<samp>libNAME.so.V</samp>’ (except for ‘<samp>libgcc_s</samp>’, where the <code>Shared 1168 Object</code> file is named ‘<samp>shr.o</samp>’ for backwards compatibility), which 1169 <ul class="no-bullet"> 1170<li>- is used for runtime loading from inside the ‘<samp>libNAME.a</samp>’ file 1171 </li><li>- is used for dynamic loading via 1172 <code>dlopen("libNAME.a(libNAME.so.V)", RTLD_MEMBER)</code> 1173 </li><li>- is used for shared linking 1174 </li><li>- is used for static linking, so no separate <code>Static Archive 1175 Library</code> file is needed 1176 </li></ul> 1177</li></ul> 1178</dd> 1179<dt><code>--with-aix-soname=both</code></dt> 1180<dt><code>--with-aix-soname=svr4</code></dt> 1181<dd><p>A (second) <code>Shared Archive Library</code> file is created: 1182 </p><ul> 1183<li> using the ‘<samp>libNAME.so.V</samp>’ filename scheme 1184 </li><li> with the <code>Shared Object</code> file as archive member named 1185 ‘<samp>shr.o</samp>’, which 1186 <ul class="no-bullet"> 1187<li>- is created with the <code>-G linker flag</code> 1188 </li><li>- has the <code>F_LOADONLY</code> flag set 1189 </li><li>- is used for runtime loading from inside the ‘<samp>libNAME.so.V</samp>’ file 1190 </li><li>- is used for dynamic loading via <code>dlopen("libNAME.so.V(shr.o)", 1191 RTLD_MEMBER)</code> 1192 </li></ul> 1193</li><li> with the <code>Import File</code> as archive member named ‘<samp>shr.imp</samp>’, 1194 which 1195 <ul class="no-bullet"> 1196<li>- refers to ‘<samp>libNAME.so.V(shr.o)</samp>’ as the "SONAME", to be recorded 1197 in the <code>Loader Section</code> of subsequent binaries 1198 </li><li>- indicates whether ‘<samp>libNAME.so.V(shr.o)</samp>’ is 32 or 64 bit 1199 </li><li>- lists all the public symbols exported by ‘<samp>lib.so.V(shr.o)</samp>’, 1200 eventually decorated with the <code>‘<samp>weak</samp>’ Keyword</code> 1201 </li><li>- is necessary for shared linking against ‘<samp>lib.so.V(shr.o)</samp>’ 1202 </li></ul> 1203</li></ul> 1204<p>A symbolic link using the ‘<samp>libNAME.so</samp>’ filename scheme is created: 1205 </p><ul> 1206<li> pointing to the ‘<samp>libNAME.so.V</samp>’ <code>Shared Archive Library</code> file 1207 </li><li> to permit the <code>ld Command</code> to find ‘<samp>lib.so.V(shr.imp)</samp>’ via 1208 the ‘<samp>-lNAME</samp>’ argument (requires <code>Runtime Linking</code> to be enabled) 1209 </li><li> to permit dynamic loading of ‘<samp>lib.so.V(shr.o)</samp>’ without the need 1210 to specify the version number via <code>dlopen("libNAME.so(shr.o)", 1211 RTLD_MEMBER)</code> 1212 </li></ul> 1213</dd> 1214</dl> 1215 1216<p>As long as static library creation is enabled, upon: 1217</p><dl compact="compact"> 1218<dt><code>--with-aix-soname=svr4</code></dt> 1219<dd><p>A <code>Static Archive Library</code> is created: 1220 </p><ul> 1221<li> using the ‘<samp>libNAME.a</samp>’ filename scheme 1222 </li><li> with all the <code>Static Object</code> files as archive members, which 1223 <ul class="no-bullet"> 1224<li>- are used for static linking 1225 </li></ul> 1226</li></ul> 1227</dd> 1228</dl> 1229 1230<p>While the aix-soname=‘<samp>svr4</samp>’ option does not create <code>Shared Object</code> 1231files as members of unversioned <code>Archive Library</code> files any more, package 1232managers still are responsible to 1233<a href="./specific.html#TransferAixShobj">transfer</a> <code>Shared Object</code> files 1234found as member of a previously installed unversioned <code>Archive Library</code> 1235file into the newly installed <code>Archive Library</code> file with the same 1236filename. 1237</p> 1238<p><em>WARNING:</em> Creating <code>Shared Object</code> files with <code>Runtime Linking</code> 1239enabled may bloat the TOC, eventually leading to <code>TOC overflow</code> errors, 1240requiring the use of either the <samp>-Wl,-bbigtoc</samp> linker flag (seen to 1241break with the <code>GDB</code> debugger) or some of the TOC-related compiler flags, 1242see “RS/6000 and PowerPC Options” in the main manual. 1243</p> 1244<p><samp>--with-aix-soname</samp> is currently supported by ‘<samp>libgcc_s</samp>’ only, so 1245this option is still experimental and not for normal use yet. 1246</p> 1247<p>Default is the traditional behavior <samp>--with-aix-soname=‘<samp>aix</samp>’</samp>. 1248</p> 1249</dd> 1250<dt><code>--enable-languages=<var>lang1</var>,<var>lang2</var>,…</code></dt> 1251<dd><p>Specify that only a particular subset of compilers and 1252their runtime libraries should be built. For a list of valid values for 1253<var>langN</var> you can issue the following command in the 1254<samp>gcc</samp> directory of your GCC source tree:<br> 1255</p><div class="smallexample"> 1256<pre class="smallexample">grep ^language= */config-lang.in 1257</pre></div> 1258<p>Currently, you can use any of the following: 1259<code>all</code>, <code>default</code>, <code>ada</code>, <code>c</code>, <code>c++</code>, <code>d</code>, 1260<code>fortran</code>, <code>go</code>, <code>jit</code>, <code>lto</code>, <code>objc</code>, <code>obj-c++</code>. 1261Building the Ada compiler has special requirements, see below. 1262If you do not pass this flag, or specify the option <code>default</code>, then the 1263default languages available in the <samp>gcc</samp> sub-tree will be configured. 1264Ada, D, Go, Jit, and Objective-C++ are not default languages. LTO is not a 1265default language, but is built by default because <samp>--enable-lto</samp> is 1266enabled by default. The other languages are default languages. If 1267<code>all</code> is specified, then all available languages are built. An 1268exception is <code>jit</code> language, which requires 1269<samp>--enable-host-shared</samp> to be included with <code>all</code>. 1270</p> 1271</dd> 1272<dt><code>--enable-stage1-languages=<var>lang1</var>,<var>lang2</var>,…</code></dt> 1273<dd><p>Specify that a particular subset of compilers and their runtime 1274libraries should be built with the system C compiler during stage 1 of 1275the bootstrap process, rather than only in later stages with the 1276bootstrapped C compiler. The list of valid values is the same as for 1277<samp>--enable-languages</samp>, and the option <code>all</code> will select all 1278of the languages enabled by <samp>--enable-languages</samp>. This option is 1279primarily useful for GCC development; for instance, when a development 1280version of the compiler cannot bootstrap due to compiler bugs, or when 1281one is debugging front ends other than the C front end. When this 1282option is used, one can then build the target libraries for the 1283specified languages with the stage-1 compiler by using <code>make 1284stage1-bubble all-target</code>, or run the testsuite on the stage-1 compiler 1285for the specified languages using <code>make stage1-start check-gcc</code>. 1286</p> 1287</dd> 1288<dt><code>--disable-libada</code></dt> 1289<dd><p>Specify that the run-time libraries and tools used by GNAT should not 1290be built. This can be useful for debugging, or for compatibility with 1291previous Ada build procedures, when it was required to explicitly 1292do a ‘<samp>make -C gcc gnatlib_and_tools</samp>’. 1293</p> 1294</dd> 1295<dt><code>--disable-libsanitizer</code></dt> 1296<dd><p>Specify that the run-time libraries for the various sanitizers should 1297not be built. 1298</p> 1299</dd> 1300<dt><code>--disable-libssp</code></dt> 1301<dd><p>Specify that the run-time libraries for stack smashing protection 1302should not be built or linked against. On many targets library support 1303is provided by the C library instead. 1304</p> 1305</dd> 1306<dt><code>--disable-libquadmath</code></dt> 1307<dd><p>Specify that the GCC quad-precision math library should not be built. 1308On some systems, the library is required to be linkable when building 1309the Fortran front end, unless <samp>--disable-libquadmath-support</samp> 1310is used. 1311</p> 1312</dd> 1313<dt><code>--disable-libquadmath-support</code></dt> 1314<dd><p>Specify that the Fortran front end and <code>libgfortran</code> do not add 1315support for <code>libquadmath</code> on systems supporting it. 1316</p> 1317</dd> 1318<dt><code>--disable-libgomp</code></dt> 1319<dd><p>Specify that the GNU Offloading and Multi Processing Runtime Library 1320should not be built. 1321</p> 1322</dd> 1323<dt><code>--disable-libvtv</code></dt> 1324<dd><p>Specify that the run-time libraries used by vtable verification 1325should not be built. 1326</p> 1327</dd> 1328<dt><code>--with-dwarf2</code></dt> 1329<dd><p>Specify that the compiler should 1330use DWARF 2 debugging information as the default. 1331</p> 1332</dd> 1333<dt><code>--with-advance-toolchain=<var>at</var></code></dt> 1334<dd><p>On 64-bit PowerPC Linux systems, configure the compiler to use the 1335header files, library files, and the dynamic linker from the Advance 1336Toolchain release <var>at</var> instead of the default versions that are 1337provided by the Linux distribution. In general, this option is 1338intended for the developers of GCC, and it is not intended for general 1339use. 1340</p> 1341</dd> 1342<dt><code>--enable-targets=all</code></dt> 1343<dt><code>--enable-targets=<var>target_list</var></code></dt> 1344<dd><p>Some GCC targets, e.g. powerpc64-linux, build bi-arch compilers. 1345These are compilers that are able to generate either 64-bit or 32-bit 1346code. Typically, the corresponding 32-bit target, e.g. 1347powerpc-linux for powerpc64-linux, only generates 32-bit code. This 1348option enables the 32-bit target to be a bi-arch compiler, which is 1349useful when you want a bi-arch compiler that defaults to 32-bit, and 1350you are building a bi-arch or multi-arch binutils in a combined tree. 1351On mips-linux, this will build a tri-arch compiler (ABI o32/n32/64), 1352defaulted to o32. 1353Currently, this option only affects sparc-linux, powerpc-linux, x86-linux, 1354mips-linux and s390-linux. 1355</p> 1356</dd> 1357<dt><code>--enable-default-pie</code></dt> 1358<dd><p>Turn on <samp>-fPIE</samp> and <samp>-pie</samp> by default. 1359</p> 1360</dd> 1361<dt><code>--enable-secureplt</code></dt> 1362<dd><p>This option enables <samp>-msecure-plt</samp> by default for powerpc-linux. 1363See “RS/6000 and PowerPC Options” in the main manual 1364</p> 1365</dd> 1366<dt><code>--enable-default-ssp</code></dt> 1367<dd><p>Turn on <samp>-fstack-protector-strong</samp> by default. 1368</p> 1369</dd> 1370<dt><code>--enable-cld</code></dt> 1371<dd><p>This option enables <samp>-mcld</samp> by default for 32-bit x86 targets. 1372See “i386 and x86-64 Options” in the main manual 1373</p> 1374</dd> 1375<dt><code>--enable-large-address-aware</code></dt> 1376<dd><p>The <samp>--enable-large-address-aware</samp> option arranges for MinGW 1377executables to be linked using the <samp>--large-address-aware</samp> 1378option, that enables the use of more than 2GB of memory. If GCC is 1379configured with this option, its effects can be reversed by passing the 1380<samp>-Wl,--disable-large-address-aware</samp> option to the so-configured 1381compiler driver. 1382</p> 1383</dd> 1384<dt><code>--enable-win32-registry</code></dt> 1385<dt><code>--enable-win32-registry=<var>key</var></code></dt> 1386<dt><code>--disable-win32-registry</code></dt> 1387<dd><p>The <samp>--enable-win32-registry</samp> option enables Microsoft Windows-hosted GCC 1388to look up installations paths in the registry using the following key: 1389</p> 1390<div class="smallexample"> 1391<pre class="smallexample"><code>HKEY_LOCAL_MACHINE\SOFTWARE\Free Software Foundation\<var>key</var></code> 1392</pre></div> 1393 1394<p><var>key</var> defaults to GCC version number, and can be overridden by the 1395<samp>--enable-win32-registry=<var>key</var></samp> option. Vendors and distributors 1396who use custom installers are encouraged to provide a different key, 1397perhaps one comprised of vendor name and GCC version number, to 1398avoid conflict with existing installations. This feature is enabled 1399by default, and can be disabled by <samp>--disable-win32-registry</samp> 1400option. This option has no effect on the other hosts. 1401</p> 1402</dd> 1403<dt><code>--nfp</code></dt> 1404<dd><p>Specify that the machine does not have a floating point unit. This 1405option only applies to ‘<samp>m68k-sun-sunos<var>n</var></samp>’. On any other 1406system, <samp>--nfp</samp> has no effect. 1407</p> 1408</dd> 1409<dt><code>--enable-werror</code></dt> 1410<dt><code>--disable-werror</code></dt> 1411<dt><code>--enable-werror=yes</code></dt> 1412<dt><code>--enable-werror=no</code></dt> 1413<dd><p>When you specify this option, it controls whether certain files in the 1414compiler are built with <samp>-Werror</samp> in bootstrap stage2 and later. 1415If you don’t specify it, <samp>-Werror</samp> is turned on for the main 1416development trunk. However it defaults to off for release branches and 1417final releases. The specific files which get <samp>-Werror</samp> are 1418controlled by the Makefiles. 1419</p> 1420</dd> 1421<dt><code>--enable-checking</code></dt> 1422<dt><code>--disable-checking</code></dt> 1423<dt><code>--enable-checking=<var>list</var></code></dt> 1424<dd><p>This option controls performing internal consistency checks in the compiler. 1425It does not change the generated code, but adds error checking of the 1426requested complexity. This slows down the compiler and may only work 1427properly if you are building the compiler with GCC. 1428</p> 1429<p>When the option is not specified, the active set of checks depends on context. 1430Namely, bootstrap stage 1 defaults to ‘<samp>--enable-checking=yes</samp>’, builds 1431from release branches or release archives default to 1432‘<samp>--enable-checking=release</samp>’, and otherwise 1433‘<samp>--enable-checking=yes,extra</samp>’ is used. When the option is 1434specified without a <var>list</var>, the result is the same as 1435‘<samp>--enable-checking=yes</samp>’. Likewise, ‘<samp>--disable-checking</samp>’ is 1436equivalent to ‘<samp>--enable-checking=no</samp>’. 1437</p> 1438<p>The categories of checks available in <var>list</var> are ‘<samp>yes</samp>’ (most common 1439checks ‘<samp>assert,misc,gc,gimple,rtlflag,runtime,tree,types</samp>’), ‘<samp>no</samp>’ 1440(no checks at all), ‘<samp>all</samp>’ (all but ‘<samp>valgrind</samp>’), ‘<samp>release</samp>’ 1441(cheapest checks ‘<samp>assert,runtime</samp>’) or ‘<samp>none</samp>’ (same as ‘<samp>no</samp>’). 1442‘<samp>release</samp>’ checks are always on and to disable them 1443‘<samp>--disable-checking</samp>’ or ‘<samp>--enable-checking=no[,<other checks>]</samp>’ 1444must be explicitly requested. Disabling assertions makes the compiler and 1445runtime slightly faster but increases the risk of undetected internal errors 1446causing wrong code to be generated. 1447</p> 1448<p>Individual checks can be enabled with these flags: ‘<samp>assert</samp>’, ‘<samp>df</samp>’, 1449‘<samp>extra</samp>’, ‘<samp>fold</samp>’, ‘<samp>gc</samp>’, ‘<samp>gcac</samp>’, ‘<samp>gimple</samp>’, 1450‘<samp>misc</samp>’, ‘<samp>rtl</samp>’, ‘<samp>rtlflag</samp>’, ‘<samp>runtime</samp>’, ‘<samp>tree</samp>’, 1451‘<samp>types</samp>’ and ‘<samp>valgrind</samp>’. ‘<samp>extra</samp>’ extends ‘<samp>misc</samp>’ 1452checking with extra checks that might affect code generation and should 1453therefore not differ between stage1 and later stages in bootstrap. 1454</p> 1455<p>The ‘<samp>valgrind</samp>’ check requires the external <code>valgrind</code> simulator, 1456available from <a href="http://valgrind.org/">http://valgrind.org/</a>. The ‘<samp>rtl</samp>’ checks are 1457expensive and the ‘<samp>df</samp>’, ‘<samp>gcac</samp>’ and ‘<samp>valgrind</samp>’ checks are very 1458expensive. 1459</p> 1460</dd> 1461<dt><code>--disable-stage1-checking</code></dt> 1462<dt><code>--enable-stage1-checking</code></dt> 1463<dt><code>--enable-stage1-checking=<var>list</var></code></dt> 1464<dd><p>This option affects only bootstrap build. If no <samp>--enable-checking</samp> 1465option is specified the stage1 compiler is built with ‘<samp>yes</samp>’ checking 1466enabled, otherwise the stage1 checking flags are the same as specified by 1467<samp>--enable-checking</samp>. To build the stage1 compiler with 1468different checking options use <samp>--enable-stage1-checking</samp>. 1469The list of checking options is the same as for <samp>--enable-checking</samp>. 1470If your system is too slow or too small to bootstrap a released compiler 1471with checking for stage1 enabled, you can use ‘<samp>--disable-stage1-checking</samp>’ 1472to disable checking for the stage1 compiler. 1473</p> 1474</dd> 1475<dt><code>--enable-coverage</code></dt> 1476<dt><code>--enable-coverage=<var>level</var></code></dt> 1477<dd><p>With this option, the compiler is built to collect self coverage 1478information, every time it is run. This is for internal development 1479purposes, and only works when the compiler is being built with gcc. The 1480<var>level</var> argument controls whether the compiler is built optimized or 1481not, values are ‘<samp>opt</samp>’ and ‘<samp>noopt</samp>’. For coverage analysis you 1482want to disable optimization, for performance analysis you want to 1483enable optimization. When coverage is enabled, the default level is 1484without optimization. 1485</p> 1486</dd> 1487<dt><code>--enable-gather-detailed-mem-stats</code></dt> 1488<dd><p>When this option is specified more detailed information on memory 1489allocation is gathered. This information is printed when using 1490<samp>-fmem-report</samp>. 1491</p> 1492</dd> 1493<dt><code>--enable-valgrind-annotations</code></dt> 1494<dd><p>Mark selected memory related operations in the compiler when run under 1495valgrind to suppress false positives. 1496</p> 1497</dd> 1498<dt><code>--enable-nls</code></dt> 1499<dt><code>--disable-nls</code></dt> 1500<dd><p>The <samp>--enable-nls</samp> option enables Native Language Support (NLS), 1501which lets GCC output diagnostics in languages other than American 1502English. Native Language Support is enabled by default if not doing a 1503canadian cross build. The <samp>--disable-nls</samp> option disables NLS. 1504</p> 1505</dd> 1506<dt><code>--with-included-gettext</code></dt> 1507<dd><p>If NLS is enabled, the <samp>--with-included-gettext</samp> option causes the build 1508procedure to prefer its copy of GNU <code>gettext</code>. 1509</p> 1510</dd> 1511<dt><code>--with-catgets</code></dt> 1512<dd><p>If NLS is enabled, and if the host lacks <code>gettext</code> but has the 1513inferior <code>catgets</code> interface, the GCC build procedure normally 1514ignores <code>catgets</code> and instead uses GCC’s copy of the GNU 1515<code>gettext</code> library. The <samp>--with-catgets</samp> option causes the 1516build procedure to use the host’s <code>catgets</code> in this situation. 1517</p> 1518</dd> 1519<dt><code>--with-libiconv-prefix=<var>dir</var></code></dt> 1520<dd><p>Search for libiconv header files in <samp><var>dir</var>/include</samp> and 1521libiconv library files in <samp><var>dir</var>/lib</samp>. 1522</p> 1523</dd> 1524<dt><code>--enable-obsolete</code></dt> 1525<dd><p>Enable configuration for an obsoleted system. If you attempt to 1526configure GCC for a system (build, host, or target) which has been 1527obsoleted, and you do not specify this flag, configure will halt with an 1528error message. 1529</p> 1530<p>All support for systems which have been obsoleted in one release of GCC 1531is removed entirely in the next major release, unless someone steps 1532forward to maintain the port. 1533</p> 1534</dd> 1535<dt><code>--enable-decimal-float</code></dt> 1536<dt><code>--enable-decimal-float=yes</code></dt> 1537<dt><code>--enable-decimal-float=no</code></dt> 1538<dt><code>--enable-decimal-float=bid</code></dt> 1539<dt><code>--enable-decimal-float=dpd</code></dt> 1540<dt><code>--disable-decimal-float</code></dt> 1541<dd><p>Enable (or disable) support for the C decimal floating point extension 1542that is in the IEEE 754-2008 standard. This is enabled by default only 1543on PowerPC, i386, and x86_64 GNU/Linux systems. Other systems may also 1544support it, but require the user to specifically enable it. You can 1545optionally control which decimal floating point format is used (either 1546‘<samp>bid</samp>’ or ‘<samp>dpd</samp>’). The ‘<samp>bid</samp>’ (binary integer decimal) 1547format is default on i386 and x86_64 systems, and the ‘<samp>dpd</samp>’ 1548(densely packed decimal) format is default on PowerPC systems. 1549</p> 1550</dd> 1551<dt><code>--enable-fixed-point</code></dt> 1552<dt><code>--disable-fixed-point</code></dt> 1553<dd><p>Enable (or disable) support for C fixed-point arithmetic. 1554This option is enabled by default for some targets (such as MIPS) which 1555have hardware-support for fixed-point operations. On other targets, you 1556may enable this option manually. 1557</p> 1558</dd> 1559<dt><code>--with-long-double-128</code></dt> 1560<dd><p>Specify if <code>long double</code> type should be 128-bit by default on selected 1561GNU/Linux architectures. If using <code>--without-long-double-128</code>, 1562<code>long double</code> will be by default 64-bit, the same as <code>double</code> type. 1563When neither of these configure options are used, the default will be 1564128-bit <code>long double</code> when built against GNU C Library 2.4 and later, 156564-bit <code>long double</code> otherwise. 1566</p> 1567</dd> 1568<dt><code>--with-long-double-format=ibm</code></dt> 1569<dt><code>--with-long-double-format=ieee</code></dt> 1570<dd><p>Specify whether <code>long double</code> uses the IBM extended double format 1571or the IEEE 128-bit floating point format on PowerPC Linux systems. 1572This configuration switch will only work on little endian PowerPC 1573Linux systems and on big endian 64-bit systems where the default cpu 1574is at least power7 (i.e. <samp>--with-cpu=power7</samp>, 1575<samp>--with-cpu=power8</samp>, or <samp>--with-cpu=power9</samp> is used). 1576</p> 1577<p>If you use the <samp>--with-long-double-64</samp> configuration option, 1578the <samp>--with-long-double-format=ibm</samp> and 1579<samp>--with-long-double-format=ieee</samp> options are ignored. 1580</p> 1581<p>The default <code>long double</code> format is to use IBM extended double. 1582Until all of the libraries are converted to use IEEE 128-bit floating 1583point, it is not recommended to use 1584<samp>--with-long-double-format=ieee</samp>. 1585</p> 1586<p>On little endian PowerPC Linux systems, if you explicitly set the 1587<code>long double</code> type, it will build multilibs to allow you to 1588select either <code>long double</code> format, unless you disable multilibs 1589with the <code>--disable-multilib</code> option. At present, 1590<code>long double</code> multilibs are not built on big endian PowerPC Linux 1591systems. If you are building multilibs, you will need to configure 1592the compiler using the <samp>--with-system-zlib</samp> option. 1593</p> 1594<p>If you do not set the <code>long double</code> type explicitly, no multilibs 1595will be generated. 1596</p> 1597</dd> 1598<dt><code>--enable-fdpic</code></dt> 1599<dd><p>On SH Linux systems, generate ELF FDPIC code. 1600</p> 1601</dd> 1602<dt><code>--with-gmp=<var>pathname</var></code></dt> 1603<dt><code>--with-gmp-include=<var>pathname</var></code></dt> 1604<dt><code>--with-gmp-lib=<var>pathname</var></code></dt> 1605<dt><code>--with-mpfr=<var>pathname</var></code></dt> 1606<dt><code>--with-mpfr-include=<var>pathname</var></code></dt> 1607<dt><code>--with-mpfr-lib=<var>pathname</var></code></dt> 1608<dt><code>--with-mpc=<var>pathname</var></code></dt> 1609<dt><code>--with-mpc-include=<var>pathname</var></code></dt> 1610<dt><code>--with-mpc-lib=<var>pathname</var></code></dt> 1611<dd><p>If you want to build GCC but do not have the GMP library, the MPFR 1612library and/or the MPC library installed in a standard location and 1613do not have their sources present in the GCC source tree then you 1614can explicitly specify the directory where they are installed 1615(‘<samp>--with-gmp=<var>gmpinstalldir</var></samp>’, 1616‘<samp>--with-mpfr=<var>mpfrinstalldir</var></samp>’, 1617‘<samp>--with-mpc=<var>mpcinstalldir</var></samp>’). The 1618<samp>--with-gmp=<var>gmpinstalldir</var></samp> option is shorthand for 1619<samp>--with-gmp-lib=<var>gmpinstalldir</var>/lib</samp> and 1620<samp>--with-gmp-include=<var>gmpinstalldir</var>/include</samp>. Likewise the 1621<samp>--with-mpfr=<var>mpfrinstalldir</var></samp> option is shorthand for 1622<samp>--with-mpfr-lib=<var>mpfrinstalldir</var>/lib</samp> and 1623<samp>--with-mpfr-include=<var>mpfrinstalldir</var>/include</samp>, also the 1624<samp>--with-mpc=<var>mpcinstalldir</var></samp> option is shorthand for 1625<samp>--with-mpc-lib=<var>mpcinstalldir</var>/lib</samp> and 1626<samp>--with-mpc-include=<var>mpcinstalldir</var>/include</samp>. If these 1627shorthand assumptions are not correct, you can use the explicit 1628include and lib options directly. You might also need to ensure the 1629shared libraries can be found by the dynamic linker when building and 1630using GCC, for example by setting the runtime shared library path 1631variable (<code>LD_LIBRARY_PATH</code> on GNU/Linux and Solaris systems). 1632</p> 1633<p>These flags are applicable to the host platform only. When building 1634a cross compiler, they will not be used to configure target libraries. 1635</p> 1636</dd> 1637<dt><code>--with-isl=<var>pathname</var></code></dt> 1638<dt><code>--with-isl-include=<var>pathname</var></code></dt> 1639<dt><code>--with-isl-lib=<var>pathname</var></code></dt> 1640<dd><p>If you do not have the isl library installed in a standard location and you 1641want to build GCC, you can explicitly specify the directory where it is 1642installed (‘<samp>--with-isl=<var>islinstalldir</var></samp>’). The 1643<samp>--with-isl=<var>islinstalldir</var></samp> option is shorthand for 1644<samp>--with-isl-lib=<var>islinstalldir</var>/lib</samp> and 1645<samp>--with-isl-include=<var>islinstalldir</var>/include</samp>. If this 1646shorthand assumption is not correct, you can use the explicit 1647include and lib options directly. 1648</p> 1649<p>These flags are applicable to the host platform only. When building 1650a cross compiler, they will not be used to configure target libraries. 1651</p> 1652</dd> 1653<dt><code>--with-stage1-ldflags=<var>flags</var></code></dt> 1654<dd><p>This option may be used to set linker flags to be used when linking 1655stage 1 of GCC. These are also used when linking GCC if configured with 1656<samp>--disable-bootstrap</samp>. If <samp>--with-stage1-libs</samp> is not set to a 1657value, then the default is ‘<samp>-static-libstdc++ -static-libgcc</samp>’, if 1658supported. 1659</p> 1660</dd> 1661<dt><code>--with-stage1-libs=<var>libs</var></code></dt> 1662<dd><p>This option may be used to set libraries to be used when linking stage 1 1663of GCC. These are also used when linking GCC if configured with 1664<samp>--disable-bootstrap</samp>. 1665</p> 1666</dd> 1667<dt><code>--with-boot-ldflags=<var>flags</var></code></dt> 1668<dd><p>This option may be used to set linker flags to be used when linking 1669stage 2 and later when bootstrapping GCC. If –with-boot-libs 1670is not is set to a value, then the default is 1671‘<samp>-static-libstdc++ -static-libgcc</samp>’. 1672</p> 1673</dd> 1674<dt><code>--with-boot-libs=<var>libs</var></code></dt> 1675<dd><p>This option may be used to set libraries to be used when linking stage 2 1676and later when bootstrapping GCC. 1677</p> 1678</dd> 1679<dt><code>--with-debug-prefix-map=<var>map</var></code></dt> 1680<dd><p>Convert source directory names using <samp>-fdebug-prefix-map</samp> when 1681building runtime libraries. ‘<samp><var>map</var></samp>’ is a space-separated 1682list of maps of the form ‘<samp><var>old</var>=<var>new</var></samp>’. 1683</p> 1684</dd> 1685<dt><code>--enable-linker-build-id</code></dt> 1686<dd><p>Tells GCC to pass <samp>--build-id</samp> option to the linker for all final 1687links (links performed without the <samp>-r</samp> or <samp>--relocatable</samp> 1688option), if the linker supports it. If you specify 1689<samp>--enable-linker-build-id</samp>, but your linker does not 1690support <samp>--build-id</samp> option, a warning is issued and the 1691<samp>--enable-linker-build-id</samp> option is ignored. The default is off. 1692</p> 1693</dd> 1694<dt><code>--with-linker-hash-style=<var>choice</var></code></dt> 1695<dd><p>Tells GCC to pass <samp>--hash-style=<var>choice</var></samp> option to the 1696linker for all final links. <var>choice</var> can be one of 1697‘<samp>sysv</samp>’, ‘<samp>gnu</samp>’, and ‘<samp>both</samp>’ where ‘<samp>sysv</samp>’ is the default. 1698</p> 1699</dd> 1700<dt><code>--enable-gnu-unique-object</code></dt> 1701<dt><code>--disable-gnu-unique-object</code></dt> 1702<dd><p>Tells GCC to use the gnu_unique_object relocation for C++ template 1703static data members and inline function local statics. Enabled by 1704default for a toolchain with an assembler that accepts it and 1705GLIBC 2.11 or above, otherwise disabled. 1706</p> 1707</dd> 1708<dt><code>--with-diagnostics-color=<var>choice</var></code></dt> 1709<dd><p>Tells GCC to use <var>choice</var> as the default for <samp>-fdiagnostics-color=</samp> 1710option (if not used explicitly on the command line). <var>choice</var> 1711can be one of ‘<samp>never</samp>’, ‘<samp>auto</samp>’, ‘<samp>always</samp>’, and ‘<samp>auto-if-env</samp>’ 1712where ‘<samp>auto</samp>’ is the default. ‘<samp>auto-if-env</samp>’ makes 1713<samp>-fdiagnostics-color=auto</samp> the default if <code>GCC_COLORS</code> 1714is present and non-empty in the environment of the compiler, and 1715<samp>-fdiagnostics-color=never</samp> otherwise. 1716</p> 1717</dd> 1718<dt><code>--with-diagnostics-urls=<var>choice</var></code></dt> 1719<dd><p>Tells GCC to use <var>choice</var> as the default for <samp>-fdiagnostics-urls=</samp> 1720option (if not used explicitly on the command line). <var>choice</var> 1721can be one of ‘<samp>never</samp>’, ‘<samp>auto</samp>’, ‘<samp>always</samp>’, and ‘<samp>auto-if-env</samp>’ 1722where ‘<samp>auto</samp>’ is the default. ‘<samp>auto-if-env</samp>’ makes 1723<samp>-fdiagnostics-urls=auto</samp> the default if <code>GCC_URLS</code> 1724or <code>TERM_URLS</code> is present and non-empty in the environment of the 1725compiler, and <samp>-fdiagnostics-urls=never</samp> otherwise. 1726</p> 1727</dd> 1728<dt><code>--enable-lto</code></dt> 1729<dt><code>--disable-lto</code></dt> 1730<dd><p>Enable support for link-time optimization (LTO). This is enabled by 1731default, and may be disabled using <samp>--disable-lto</samp>. 1732</p> 1733</dd> 1734<dt><code>--enable-linker-plugin-configure-flags=FLAGS</code></dt> 1735<dt><code>--enable-linker-plugin-flags=FLAGS</code></dt> 1736<dd><p>By default, linker plugins (such as the LTO plugin) are built for the 1737host system architecture. For the case that the linker has a 1738different (but run-time compatible) architecture, these flags can be 1739specified to build plugins that are compatible to the linker. For 1740example, if you are building GCC for a 64-bit x86_64 1741(‘<samp>x86_64-pc-linux-gnu</samp>’) host system, but have a 32-bit x86 1742GNU/Linux (‘<samp>i686-pc-linux-gnu</samp>’) linker executable (which is 1743executable on the former system), you can configure GCC as follows for 1744getting compatible linker plugins: 1745</p> 1746<div class="smallexample"> 1747<pre class="smallexample">% <var>srcdir</var>/configure \ 1748 --host=x86_64-pc-linux-gnu \ 1749 --enable-linker-plugin-configure-flags=--host=i686-pc-linux-gnu \ 1750 --enable-linker-plugin-flags='CC=gcc\ -m32\ -Wl,-rpath,[...]/i686-pc-linux-gnu/lib' 1751</pre></div> 1752 1753</dd> 1754<dt><code>--with-plugin-ld=<var>pathname</var></code></dt> 1755<dd><p>Enable an alternate linker to be used at link-time optimization (LTO) 1756link time when <samp>-fuse-linker-plugin</samp> is enabled. 1757This linker should have plugin support such as gold starting with 1758version 2.20 or GNU ld starting with version 2.21. 1759See <samp>-fuse-linker-plugin</samp> for details. 1760</p> 1761</dd> 1762<dt><code>--enable-canonical-system-headers</code></dt> 1763<dt><code>--disable-canonical-system-headers</code></dt> 1764<dd><p>Enable system header path canonicalization for <samp>libcpp</samp>. This can 1765produce shorter header file paths in diagnostics and dependency output 1766files, but these changed header paths may conflict with some compilation 1767environments. Enabled by default, and may be disabled using 1768<samp>--disable-canonical-system-headers</samp>. 1769</p> 1770</dd> 1771<dt><code>--with-glibc-version=<var>major</var>.<var>minor</var></code></dt> 1772<dd><p>Tell GCC that when the GNU C Library (glibc) is used on the target it 1773will be version <var>major</var>.<var>minor</var> or later. Normally this can 1774be detected from the C library’s header files, but this option may be 1775needed when bootstrapping a cross toolchain without the header files 1776available for building the initial bootstrap compiler. 1777</p> 1778<p>If GCC is configured with some multilibs that use glibc and some that 1779do not, this option applies only to the multilibs that use glibc. 1780However, such configurations may not work well as not all the relevant 1781configuration in GCC is on a per-multilib basis. 1782</p> 1783</dd> 1784<dt><code>--enable-as-accelerator-for=<var>target</var></code></dt> 1785<dd><p>Build as offload target compiler. Specify offload host triple by <var>target</var>. 1786</p> 1787</dd> 1788<dt><code>--enable-offload-targets=<var>target1</var>[=<var>path1</var>],…,<var>targetN</var>[=<var>pathN</var>]</code></dt> 1789<dd><p>Enable offloading to targets <var>target1</var>, …, <var>targetN</var>. 1790Offload compilers are expected to be already installed. Default search 1791path for them is <samp><var>exec-prefix</var></samp>, but it can be changed by 1792specifying paths <var>path1</var>, …, <var>pathN</var>. 1793</p> 1794<div class="smallexample"> 1795<pre class="smallexample">% <var>srcdir</var>/configure \ 1796 --enable-offload-targets=x86_64-intelmicemul-linux-gnu=/path/to/x86_64/compiler,nvptx-none,hsa 1797</pre></div> 1798 1799<p>If ‘<samp>hsa</samp>’ is specified as one of the targets, the compiler will be 1800built with support for HSA GPU accelerators. Because the same 1801compiler will emit the accelerator code, no path should be specified. 1802</p> 1803</dd> 1804<dt><code>--with-hsa-runtime=<var>pathname</var></code></dt> 1805<dt><code>--with-hsa-runtime-include=<var>pathname</var></code></dt> 1806<dt><code>--with-hsa-runtime-lib=<var>pathname</var></code></dt> 1807<dd> 1808<p>If you configure GCC with HSA offloading but do not have the HSA 1809run-time library installed in a standard location then you can 1810explicitly specify the directory where they are installed. The 1811<samp>--with-hsa-runtime=<var>hsainstalldir</var></samp> option is a 1812shorthand for 1813<samp>--with-hsa-runtime-lib=<var>hsainstalldir</var>/lib</samp> and 1814<samp>--with-hsa-runtime-include=<var>hsainstalldir</var>/include</samp>. 1815</p> 1816</dd> 1817<dt><code>--enable-cet</code></dt> 1818<dt><code>--disable-cet</code></dt> 1819<dd><p>Enable building target run-time libraries with control-flow 1820instrumentation, see <samp>-fcf-protection</samp> option. When 1821<code>--enable-cet</code> is specified target libraries are configured 1822to add <samp>-fcf-protection</samp> and, if needed, other target 1823specific options to a set of building options. 1824</p> 1825<p>The option is disabled by default. When <code>--enable-cet=auto</code> 1826is used, it is enabled on Linux/x86 if target binutils 1827supports <code>Intel CET</code> instructions and disabled otherwise. 1828In this case the target libraries are configured to get additional 1829<samp>-fcf-protection</samp> option. 1830</p> 1831</dd> 1832<dt><code>--with-riscv-attribute=‘<samp>yes</samp>’, ‘<samp>no</samp>’ or ‘<samp>default</samp>’</code></dt> 1833<dd><p>Generate RISC-V attribute by default, in order to record extra build 1834information in object. 1835</p> 1836<p>The option is disabled by default. It is enabled on RISC-V/ELF (bare-metal) 1837target if target binutils supported. 1838</p></dd> 1839</dl> 1840 1841<a name="Cross-Compiler-Specific-Options"></a> 1842<h4 class="subheading">Cross-Compiler-Specific Options</h4> 1843<p>The following options only apply to building cross compilers. 1844</p> 1845<dl compact="compact"> 1846<dt><code>--with-toolexeclibdir=<var>dir</var></code></dt> 1847<dd><p>Specify the installation directory for libraries built with a cross compiler. 1848The default is <samp>${gcc_tooldir}/lib</samp>. 1849</p> 1850</dd> 1851<dt><code>--with-sysroot</code></dt> 1852<dt><code>--with-sysroot=<var>dir</var></code></dt> 1853<dd><p>Tells GCC to consider <var>dir</var> as the root of a tree that contains 1854(a subset of) the root filesystem of the target operating system. 1855Target system headers, libraries and run-time object files will be 1856searched for in there. More specifically, this acts as if 1857<samp>--sysroot=<var>dir</var></samp> was added to the default options of the built 1858compiler. The specified directory is not copied into the 1859install tree, unlike the options <samp>--with-headers</samp> and 1860<samp>--with-libs</samp> that this option obsoletes. The default value, 1861in case <samp>--with-sysroot</samp> is not given an argument, is 1862<samp>${gcc_tooldir}/sys-root</samp>. If the specified directory is a 1863subdirectory of <samp>${exec_prefix}</samp>, then it will be found relative to 1864the GCC binaries if the installation tree is moved. 1865</p> 1866<p>This option affects the system root for the compiler used to build 1867target libraries (which runs on the build system) and the compiler newly 1868installed with <code>make install</code>; it does not affect the compiler which is 1869used to build GCC itself. 1870</p> 1871<p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp> 1872option then the compiler will search that directory within <var>dirname</var> for 1873native system headers rather than the default <samp>/usr/include</samp>. 1874</p> 1875</dd> 1876<dt><code>--with-build-sysroot</code></dt> 1877<dt><code>--with-build-sysroot=<var>dir</var></code></dt> 1878<dd><p>Tells GCC to consider <var>dir</var> as the system root (see 1879<samp>--with-sysroot</samp>) while building target libraries, instead of 1880the directory specified with <samp>--with-sysroot</samp>. This option is 1881only useful when you are already using <samp>--with-sysroot</samp>. You 1882can use <samp>--with-build-sysroot</samp> when you are configuring with 1883<samp>--prefix</samp> set to a directory that is different from the one in 1884which you are installing GCC and your target libraries. 1885</p> 1886<p>This option affects the system root for the compiler used to build 1887target libraries (which runs on the build system); it does not affect 1888the compiler which is used to build GCC itself. 1889</p> 1890<p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp> 1891option then the compiler will search that directory within <var>dirname</var> for 1892native system headers rather than the default <samp>/usr/include</samp>. 1893</p> 1894</dd> 1895<dt><code>--with-headers</code></dt> 1896<dt><code>--with-headers=<var>dir</var></code></dt> 1897<dd><p>Deprecated in favor of <samp>--with-sysroot</samp>. 1898Specifies that target headers are available when building a cross compiler. 1899The <var>dir</var> argument specifies a directory which has the target include 1900files. These include files will be copied into the <samp>gcc</samp> install 1901directory. <em>This option with the <var>dir</var> argument is required</em> when 1902building a cross compiler, if <samp><var>prefix</var>/<var>target</var>/sys-include</samp> 1903doesn’t pre-exist. If <samp><var>prefix</var>/<var>target</var>/sys-include</samp> does 1904pre-exist, the <var>dir</var> argument may be omitted. <code>fixincludes</code> 1905will be run on these files to make them compatible with GCC. 1906</p> 1907</dd> 1908<dt><code>--without-headers</code></dt> 1909<dd><p>Tells GCC not use any target headers from a libc when building a cross 1910compiler. When crossing to GNU/Linux, you need the headers so GCC 1911can build the exception handling for libgcc. 1912</p> 1913</dd> 1914<dt><code>--with-libs</code></dt> 1915<dt><code>--with-libs="<var>dir1</var> <var>dir2</var> … <var>dirN</var>"</code></dt> 1916<dd><p>Deprecated in favor of <samp>--with-sysroot</samp>. 1917Specifies a list of directories which contain the target runtime 1918libraries. These libraries will be copied into the <samp>gcc</samp> install 1919directory. If the directory list is omitted, this option has no 1920effect. 1921</p> 1922</dd> 1923<dt><code>--with-newlib</code></dt> 1924<dd><p>Specifies that ‘<samp>newlib</samp>’ is 1925being used as the target C library. This causes <code>__eprintf</code> to be 1926omitted from <samp>libgcc.a</samp> on the assumption that it will be provided by 1927‘<samp>newlib</samp>’. 1928</p> 1929<a name="avr"></a> 1930</dd> 1931<dt><code>--with-avrlibc</code></dt> 1932<dd><p>Only supported for the AVR target. Specifies that ‘<samp>AVR-Libc</samp>’ is 1933being used as the target C library. This causes float support 1934functions like <code>__addsf3</code> to be omitted from <samp>libgcc.a</samp> on 1935the assumption that it will be provided by <samp>libm.a</samp>. For more 1936technical details, cf. <a href="http://gcc.gnu.org/PR54461">PR54461</a>. 1937It is not supported for 1938RTEMS configurations, which currently use newlib. The option is 1939supported since version 4.7.2 and is the default in 4.8.0 and newer. 1940</p> 1941</dd> 1942<dt><code>--with-double={32|64|32,64|64,32}</code></dt> 1943<dt><code>--with-long-double={32|64|32,64|64,32|double}</code></dt> 1944<dd><p>Only supported for the AVR target since version 10. 1945Specify the default layout available for the C/C++ ‘<samp>double</samp>’ 1946and ‘<samp>long double</samp>’ type, respectively. The following rules apply: 1947</p><ul> 1948<li> The first value after the ‘<samp>=</samp>’ specifies the default layout (in bits) 1949of the type and also the default for the <samp>-mdouble=</samp> resp. 1950<samp>-mlong-double=</samp> compiler option. 1951</li><li> If more than one value is specified, respective multilib variants are 1952available, and <samp>-mdouble=</samp> resp. <samp>-mlong-double=</samp> acts 1953as a multilib option. 1954</li><li> If <samp>--with-long-double=double</samp> is specified, ‘<samp>double</samp>’ and 1955‘<samp>long double</samp>’ will have the same layout. 1956</li><li> The defaults are <samp>--with-long-double=64,32</samp> and 1957<samp>--with-double=32,64</samp>. The default ‘<samp>double</samp>’ layout imposed by 1958the latter is compatible with older versions of the compiler that implement 1959‘<samp>double</samp>’ as a 32-bit type, which does not comply to the language standard. 1960</li></ul> 1961<p>Not all combinations of <samp>--with-double=</samp> and 1962<samp>--with-long-double=</samp> are valid. For example, the combination 1963<samp>--with-double=32,64</samp> <samp>--with-long-double=32</samp> will be 1964rejected because the first option specifies the availability of 1965multilibs for ‘<samp>double</samp>’, whereas the second option implies 1966that ‘<samp>long double</samp>’ — and hence also ‘<samp>double</samp>’ — is always 196732 bits wide. 1968</p> 1969</dd> 1970<dt><code>--with-double-comparison={tristate|bool|libf7}</code></dt> 1971<dd><p>Only supported for the AVR target since version 10. 1972Specify what result format is returned by library functions that 1973compare 64-bit floating point values (<code>DFmode</code>). 1974The GCC default is ‘<samp>tristate</samp>’. If the floating point 1975implementation returns a boolean instead, set it to ‘<samp>bool</samp>’. 1976</p> 1977</dd> 1978<dt><code>--with-libf7={libgcc|math|math-symbols|no}</code></dt> 1979<dd><p>Only supported for the AVR target since version 10. 1980Specify to which degree code from LibF7 is included in libgcc. 1981LibF7 is an ad-hoc, AVR-specific, 64-bit floating point emulation 1982written in C and (inline) assembly. ‘<samp>libgcc</samp>’ adds support 1983for functions that one would usually expect in libgcc like double addition, 1984double comparisons and double conversions. ‘<samp>math</samp>’ also adds routines 1985that one would expect in <samp>libm.a</samp>, but with <code>__</code> (two underscores) 1986prepended to the symbol names as specified by <samp>math.h</samp>. 1987‘<samp>math-symbols</samp>’ also defines weak aliases for the functions 1988declared in <samp>math.h</samp>. However, <code>--with-libf7</code> won’t 1989install no <samp>math.h</samp> header file whatsoever, this file must come 1990from elsewhere. This option sets <samp>--with-double-comparison</samp> 1991to ‘<samp>bool</samp>’. 1992</p> 1993</dd> 1994<dt><code>--with-nds32-lib=<var>library</var></code></dt> 1995<dd><p>Specifies that <var>library</var> setting is used for building <samp>libgcc.a</samp>. 1996Currently, the valid <var>library</var> is ‘<samp>newlib</samp>’ or ‘<samp>mculib</samp>’. 1997This option is only supported for the NDS32 target. 1998</p> 1999</dd> 2000<dt><code>--with-build-time-tools=<var>dir</var></code></dt> 2001<dd><p>Specifies where to find the set of target tools (assembler, linker, etc.) 2002that will be used while building GCC itself. This option can be useful 2003if the directory layouts are different between the system you are building 2004GCC on, and the system where you will deploy it. 2005</p> 2006<p>For example, on an ‘<samp>ia64-hp-hpux</samp>’ system, you may have the GNU 2007assembler and linker in <samp>/usr/bin</samp>, and the native tools in a 2008different path, and build a toolchain that expects to find the 2009native tools in <samp>/usr/bin</samp>. 2010</p> 2011<p>When you use this option, you should ensure that <var>dir</var> includes 2012<code>ar</code>, <code>as</code>, <code>ld</code>, <code>nm</code>, 2013<code>ranlib</code> and <code>strip</code> if necessary, and possibly 2014<code>objdump</code>. Otherwise, GCC may use an inconsistent set of 2015tools. 2016</p></dd> 2017</dl> 2018 2019<a name="Overriding-configure-test-results"></a> 2020<h4 class="subsubheading">Overriding <code>configure</code> test results</h4> 2021 2022<p>Sometimes, it might be necessary to override the result of some 2023<code>configure</code> test, for example in order to ease porting to a new 2024system or work around a bug in a test. The toplevel <code>configure</code> 2025script provides three variables for this: 2026</p> 2027<dl compact="compact"> 2028<dt><code>build_configargs</code></dt> 2029<dd><a name="index-build_005fconfigargs"></a> 2030<p>The contents of this variable is passed to all build <code>configure</code> 2031scripts. 2032</p> 2033</dd> 2034<dt><code>host_configargs</code></dt> 2035<dd><a name="index-host_005fconfigargs"></a> 2036<p>The contents of this variable is passed to all host <code>configure</code> 2037scripts. 2038</p> 2039</dd> 2040<dt><code>target_configargs</code></dt> 2041<dd><a name="index-target_005fconfigargs"></a> 2042<p>The contents of this variable is passed to all target <code>configure</code> 2043scripts. 2044</p> 2045</dd> 2046</dl> 2047 2048<p>In order to avoid shell and <code>make</code> quoting issues for complex 2049overrides, you can pass a setting for <code>CONFIG_SITE</code> and set 2050variables in the site file. 2051</p> 2052<a name="Objective-C-Specific-Options"></a> 2053<h4 class="subheading">Objective-C-Specific Options</h4> 2054 2055<p>The following options apply to the build of the Objective-C runtime library. 2056</p> 2057<dl compact="compact"> 2058<dt><code>--enable-objc-gc</code></dt> 2059<dd><p>Specify that an additional variant of the GNU Objective-C runtime library 2060is built, using an external build of the Boehm-Demers-Weiser garbage 2061collector (<a href="https://www.hboehm.info/gc/">https://www.hboehm.info/gc/</a>). This library needs to be 2062available for each multilib variant, unless configured with 2063<samp>--enable-objc-gc=‘<samp>auto</samp>’</samp> in which case the build of the 2064additional runtime library is skipped when not available and the build 2065continues. 2066</p> 2067</dd> 2068<dt><code>--with-target-bdw-gc=<var>list</var></code></dt> 2069<dt><code>--with-target-bdw-gc-include=<var>list</var></code></dt> 2070<dt><code>--with-target-bdw-gc-lib=<var>list</var></code></dt> 2071<dd><p>Specify search directories for the garbage collector header files and 2072libraries. <var>list</var> is a comma separated list of key value pairs of the 2073form ‘<samp><var>multilibdir</var>=<var>path</var></samp>’, where the default multilib key 2074is named as ‘<samp>.</samp>’ (dot), or is omitted (e.g. 2075‘<samp>--with-target-bdw-gc=/opt/bdw-gc,32=/opt-bdw-gc32</samp>’). 2076</p> 2077<p>The options <samp>--with-target-bdw-gc-include</samp> and 2078<samp>--with-target-bdw-gc-lib</samp> must always be specified together 2079for each multilib variant and they take precedence over 2080<samp>--with-target-bdw-gc</samp>. If <samp>--with-target-bdw-gc-include</samp> 2081is missing values for a multilib, then the value for the default 2082multilib is used (e.g. ‘<samp>--with-target-bdw-gc-include=/opt/bdw-gc/include</samp>’ 2083‘<samp>--with-target-bdw-gc-lib=/opt/bdw-gc/lib64,32=/opt-bdw-gc/lib32</samp>’). 2084If none of these options are specified, the library is assumed in 2085default locations. 2086</p></dd> 2087</dl> 2088 2089<a name="D-Specific-Options"></a> 2090<h4 class="subheading">D-Specific Options</h4> 2091 2092<p>The following options apply to the build of the D runtime library. 2093</p> 2094<dl compact="compact"> 2095<dt><code>--enable-libphobos-checking</code></dt> 2096<dt><code>--disable-libphobos-checking</code></dt> 2097<dt><code>--enable-libphobos-checking=<var>list</var></code></dt> 2098<dd><p>This option controls whether run-time checks and contracts are compiled into 2099the D runtime library. When the option is not specified, the library is built 2100with ‘<samp>release</samp>’ checking. When the option is specified without a 2101<var>list</var>, the result is the same as ‘<samp>--enable-libphobos-checking=yes</samp>’. 2102Likewise, ‘<samp>--disable-libphobos-checking</samp>’ is equivalent to 2103‘<samp>--enable-libphobos-checking=no</samp>’. 2104</p> 2105<p>The categories of checks available in <var>list</var> are ‘<samp>yes</samp>’ (compiles 2106libphobos with <samp>-fno-release</samp>), ‘<samp>no</samp>’ (compiles libphobos with 2107<samp>-frelease</samp>), ‘<samp>all</samp>’ (same as ‘<samp>yes</samp>’), ‘<samp>none</samp>’ or 2108‘<samp>release</samp>’ (same as ‘<samp>no</samp>’). 2109</p> 2110<p>Individual checks available in <var>list</var> are ‘<samp>assert</samp>’ (compiles libphobos 2111with an extra option <samp>-fassert</samp>). 2112</p> 2113</dd> 2114<dt><code>--with-libphobos-druntime-only</code></dt> 2115<dt><code>--with-libphobos-druntime-only=<var>choice</var></code></dt> 2116<dd><p>Specify whether to build only the core D runtime library (druntime), or both 2117the core and standard library (phobos) into libphobos. This is useful for 2118targets that have full support in druntime, but no or incomplete support 2119in phobos. <var>choice</var> can be one of ‘<samp>auto</samp>’, ‘<samp>yes</samp>’, and ‘<samp>no</samp>’ 2120where ‘<samp>auto</samp>’ is the default. 2121</p> 2122<p>When the option is not specified, the default choice ‘<samp>auto</samp>’ means that it 2123is inferred whether the target has support for the phobos standard library. 2124When the option is specified without a <var>choice</var>, the result is the same as 2125‘<samp>--with-libphobos-druntime-only=yes</samp>’. 2126</p> 2127</dd> 2128<dt><code>--with-target-system-zlib</code></dt> 2129<dd><p>Use installed ‘<samp>zlib</samp>’ rather than that included with GCC. This needs 2130to be available for each multilib variant, unless configured with 2131<samp>--with-target-system-zlib=‘<samp>auto</samp>’</samp> in which case the GCC included 2132‘<samp>zlib</samp>’ is only used when the system installed library is not available. 2133</p></dd> 2134</dl> 2135 2136<hr /> 2137<p> 2138<p><a href="./index.html">Return to the GCC Installation page</a> 2139</p> 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151</body> 2152</html> 2153