configure.html revision 1.1.1.17
1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2 <html> 3 <!-- Created by GNU Texinfo 6.8, https://www.gnu.org/software/texinfo/ --> 4 <head> 5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 6 <!-- Copyright (C) 1988-2020 Free Software Foundation, Inc. 7 8 Permission is granted to copy, distribute and/or modify this document 9 under the terms of the GNU Free Documentation License, Version 1.3 or 10 any later version published by the Free Software Foundation; with no 11 Invariant Sections, the Front-Cover texts being (a) (see below), and 12 with the Back-Cover Texts being (b) (see below). A copy of the 13 license is included in the section entitled "GNU 14 Free Documentation License". 15 16 (a) The FSF's Front-Cover Text is: 17 18 A GNU Manual 19 20 (b) The FSF's Back-Cover Text is: 21 22 You have freedom to copy and modify this GNU Manual, like GNU 23 software. Copies published by the Free Software Foundation raise 24 funds for GNU development. --> 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 <meta name="viewport" content="width=device-width,initial-scale=1"> 33 34 <style type="text/css"> 35 <!-- 36 a.copiable-anchor {visibility: hidden; text-decoration: none; line-height: 0em} 37 a.summary-letter {text-decoration: none} 38 blockquote.indentedblock {margin-right: 0em} 39 div.display {margin-left: 3.2em} 40 div.example {margin-left: 3.2em} 41 kbd {font-style: oblique} 42 pre.display {font-family: inherit} 43 pre.format {font-family: inherit} 44 pre.menu-comment {font-family: serif} 45 pre.menu-preformatted {font-family: serif} 46 span.nolinebreak {white-space: nowrap} 47 span.roman {font-family: initial; font-weight: normal} 48 span.sansserif {font-family: sans-serif; font-weight: normal} 49 span:hover a.copiable-anchor {visibility: visible} 50 ul.no-bullet {list-style: none} 51 --> 52 </style> 53 54 55 </head> 56 57 <body lang="en"> 58 <h1 class="settitle" align="center">Installing GCC: Configuration</h1> 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 <span id="index-Configuration"></span> 79 <span id="index-Installing-GCC_003a-Configuration"></span> 80 81 <p>Like most GNU software, GCC must be configured before it can be built. 82 This document describes the recommended configuration procedure 83 for both native and cross targets. 84 </p> 85 <p>We use <var>srcdir</var> to refer to the toplevel source directory for 86 GCC; we use <var>objdir</var> to refer to the toplevel build/object directory. 87 </p> 88 <p>If you obtained the sources by cloning the repository, <var>srcdir</var> 89 must refer to the top <samp>gcc</samp> directory, the one where the 90 <samp>MAINTAINERS</samp> file can be found, and not its <samp>gcc</samp> 91 subdirectory, otherwise the build will fail. 92 </p> 93 <p>If either <var>srcdir</var> or <var>objdir</var> is located on an automounted NFS 94 file system, the shell’s built-in <code>pwd</code> command will return 95 temporary pathnames. Using these can lead to various sorts of build 96 problems. To avoid this issue, set the <code>PWDCMD</code> environment 97 variable to an automounter-aware <code>pwd</code> command, e.g., 98 <code>pawd</code> or ‘<samp>amq -w</samp>’, during the configuration and build 99 phases. 100 </p> 101 <p>First, we <strong>highly</strong> recommend that GCC be built into a 102 separate directory from the sources which does <strong>not</strong> reside 103 within the source tree. This is how we generally build GCC; building 104 where <var>srcdir</var> == <var>objdir</var> should still work, but doesn’t 105 get extensive testing; building where <var>objdir</var> is a subdirectory 106 of <var>srcdir</var> is unsupported. 107 </p> 108 <p>If you have previously built GCC in the same directory for a 109 different target machine, do ‘<samp>make distclean</samp>’ to delete all files 110 that might be invalid. One of the files this deletes is <samp>Makefile</samp>; 111 if ‘<samp>make distclean</samp>’ complains that <samp>Makefile</samp> does not exist 112 or issues a message like “don’t know how to make distclean” it probably 113 means that the directory is already suitably clean. However, with the 114 recommended method of building in a separate <var>objdir</var>, you should 115 simply use a different <var>objdir</var> for each target. 116 </p> 117 <p>Second, when configuring a native system, either <code>cc</code> or 118 <code>gcc</code> must be in your path or you must set <code>CC</code> in 119 your environment before running configure. Otherwise the configuration 120 scripts may fail. 121 </p> 122 123 <p>To configure GCC: 124 </p> 125 <div class="example"> 126 <pre class="example">% mkdir <var>objdir</var> 127 % cd <var>objdir</var> 128 % <var>srcdir</var>/configure [<var>options</var>] [<var>target</var>] 129 </pre></div> 130 131 <span id="Distributor-options"></span><h3 class="heading">Distributor options</h3> 132 133 <p>If you will be distributing binary versions of GCC, with modifications 134 to the source code, you should use the options described in this 135 section to make clear that your version contains modifications. 136 </p> 137 <dl compact="compact"> 138 <dt><span><code>--with-pkgversion=<var>version</var></code></span></dt> 139 <dd><p>Specify a string that identifies your package. You may wish 140 to include a build number or build date. This version string will be 141 included in the output of <code>gcc --version</code>. This suffix does 142 not replace the default version string, only the ‘<samp>GCC</samp>’ part. 143 </p> 144 <p>The default value is ‘<samp>GCC</samp>’. 145 </p> 146 </dd> 147 <dt><span><code>--with-bugurl=<var>url</var></code></span></dt> 148 <dd><p>Specify the URL that users should visit if they wish to report a bug. 149 You are of course welcome to forward bugs reported to you to the FSF, 150 if you determine that they are not bugs in your modifications. 151 </p> 152 <p>The default value refers to the FSF’s GCC bug tracker. 153 </p> 154 </dd> 155 <dt><span><code>--with-documentation-root-url=<var>url</var></code></span></dt> 156 <dd><p>Specify the URL root that contains GCC option documentation. The <var>url</var> 157 should end with a <code>/</code> character. 158 </p> 159 <p>The default value is <a href="https://gcc.gnu.org/onlinedocs/">https://gcc.gnu.org/onlinedocs/</a>. 160 </p> 161 </dd> 162 <dt><span><code>--with-changes-root-url=<var>url</var></code></span></dt> 163 <dd><p>Specify the URL root that contains information about changes in GCC 164 releases like <code>gcc-<var>version</var>/changes.html</code>. 165 The <var>url</var> should end with a <code>/</code> character. 166 </p> 167 <p>The default value is <a href="https://gcc.gnu.org/">https://gcc.gnu.org/</a>. 168 </p> 169 </dd> 170 </dl> 171 172 <span id="Target-specification"></span><h3 class="heading">Target specification</h3> 173 <ul> 174 <li> GCC has code to correctly determine the correct value for <var>target</var> 175 for nearly all native systems. Therefore, we highly recommend you do 176 not provide a configure target when configuring a native compiler. 177 178 </li><li> <var>target</var> must be specified as <samp>--target=<var>target</var></samp> 179 when configuring a cross compiler; examples of valid targets would be 180 m68k-elf, sh-elf, etc. 181 182 </li><li> Specifying just <var>target</var> instead of <samp>--target=<var>target</var></samp> 183 implies that the host defaults to <var>target</var>. 184 </li></ul> 185 186 187 <span id="Options-specification"></span><h3 class="heading">Options specification</h3> 188 189 <p>Use <var>options</var> to override several configure time options for 190 GCC. A list of supported <var>options</var> follows; ‘<samp>configure 191 --help</samp>’ may list other options, but those not listed below may not 192 work and should not normally be used. 193 </p> 194 <p>Note that each <samp>--enable</samp> option has a corresponding 195 <samp>--disable</samp> option and that each <samp>--with</samp> option has a 196 corresponding <samp>--without</samp> option. 197 </p> 198 <dl compact="compact"> 199 <dt><span><code>--prefix=<var>dirname</var></code></span></dt> 200 <dd><p>Specify the toplevel installation 201 directory. This is the recommended way to install the tools into a directory 202 other than the default. The toplevel installation directory defaults to 203 <samp>/usr/local</samp>. 204 </p> 205 <p>We <strong>highly</strong> recommend against <var>dirname</var> being the same or a 206 subdirectory of <var>objdir</var> or vice versa. If specifying a directory 207 beneath a user’s home directory tree, some shells will not expand 208 <var>dirname</var> correctly if it contains the ‘<samp>~</samp>’ metacharacter; use 209 <code>$HOME</code> instead. 210 </p> 211 <p>The following standard <code>autoconf</code> options are supported. Normally you 212 should not need to use these options. 213 </p><dl compact="compact"> 214 <dt><span><code>--exec-prefix=<var>dirname</var></code></span></dt> 215 <dd><p>Specify the toplevel installation directory for architecture-dependent 216 files. The default is <samp><var>prefix</var></samp>. 217 </p> 218 </dd> 219 <dt><span><code>--bindir=<var>dirname</var></code></span></dt> 220 <dd><p>Specify the installation directory for the executables called by users 221 (such as <code>gcc</code> and <code>g++</code>). The default is 222 <samp><var>exec-prefix</var>/bin</samp>. 223 </p> 224 </dd> 225 <dt><span><code>--libdir=<var>dirname</var></code></span></dt> 226 <dd><p>Specify the installation directory for object code libraries and 227 internal data files of GCC. The default is <samp><var>exec-prefix</var>/lib</samp>. 228 </p> 229 </dd> 230 <dt><span><code>--libexecdir=<var>dirname</var></code></span></dt> 231 <dd><p>Specify the installation directory for internal executables of GCC. 232 The default is <samp><var>exec-prefix</var>/libexec</samp>. 233 </p> 234 </dd> 235 <dt><span><code>--with-slibdir=<var>dirname</var></code></span></dt> 236 <dd><p>Specify the installation directory for the shared libgcc library. The 237 default is <samp><var>libdir</var></samp>. 238 </p> 239 </dd> 240 <dt><span><code>--datarootdir=<var>dirname</var></code></span></dt> 241 <dd><p>Specify the root of the directory tree for read-only architecture-independent 242 data files referenced by GCC. The default is <samp><var>prefix</var>/share</samp>. 243 </p> 244 </dd> 245 <dt><span><code>--infodir=<var>dirname</var></code></span></dt> 246 <dd><p>Specify the installation directory for documentation in info format. 247 The default is <samp><var>datarootdir</var>/info</samp>. 248 </p> 249 </dd> 250 <dt><span><code>--datadir=<var>dirname</var></code></span></dt> 251 <dd><p>Specify the installation directory for some architecture-independent 252 data files referenced by GCC. The default is <samp><var>datarootdir</var></samp>. 253 </p> 254 </dd> 255 <dt><span><code>--docdir=<var>dirname</var></code></span></dt> 256 <dd><p>Specify the installation directory for documentation files (other 257 than Info) for GCC. The default is <samp><var>datarootdir</var>/doc</samp>. 258 </p> 259 </dd> 260 <dt><span><code>--htmldir=<var>dirname</var></code></span></dt> 261 <dd><p>Specify the installation directory for HTML documentation files. 262 The default is <samp><var>docdir</var></samp>. 263 </p> 264 </dd> 265 <dt><span><code>--pdfdir=<var>dirname</var></code></span></dt> 266 <dd><p>Specify the installation directory for PDF documentation files. 267 The default is <samp><var>docdir</var></samp>. 268 </p> 269 </dd> 270 <dt><span><code>--mandir=<var>dirname</var></code></span></dt> 271 <dd><p>Specify the installation directory for manual pages. The default is 272 <samp><var>datarootdir</var>/man</samp>. (Note that the manual pages are only extracts 273 from the full GCC manuals, which are provided in Texinfo format. The manpages 274 are derived by an automatic conversion process from parts of the full 275 manual.) 276 </p> 277 </dd> 278 <dt><span><code>--with-gxx-include-dir=<var>dirname</var></code></span></dt> 279 <dd><p>Specify 280 the installation directory for G++ header files. The default depends 281 on other configuration options, and differs between cross and native 282 configurations. 283 </p> 284 </dd> 285 <dt><span><code>--with-specs=<var>specs</var></code></span></dt> 286 <dd><p>Specify additional command line driver SPECS. 287 This can be useful if you need to turn on a non-standard feature by 288 default without modifying the compiler’s source code, for instance 289 <samp>--with-specs=%{!fcommon:%{!fno-common:-fno-common}}</samp>. 290 See “Spec Files” in the main manual 291 </p> 292 </dd> 293 </dl> 294 295 </dd> 296 <dt><span><code>--program-prefix=<var>prefix</var></code></span></dt> 297 <dd><p>GCC supports some transformations of the names of its programs when 298 installing them. This option prepends <var>prefix</var> to the names of 299 programs to install in <var>bindir</var> (see above). For example, specifying 300 <samp>--program-prefix=foo-</samp> would result in ‘<samp>gcc</samp>’ 301 being installed as <samp>/usr/local/bin/foo-gcc</samp>. 302 </p> 303 </dd> 304 <dt><span><code>--program-suffix=<var>suffix</var></code></span></dt> 305 <dd><p>Appends <var>suffix</var> to the names of programs to install in <var>bindir</var> 306 (see above). For example, specifying <samp>--program-suffix=-3.1</samp> 307 would result in ‘<samp>gcc</samp>’ being installed as 308 <samp>/usr/local/bin/gcc-3.1</samp>. 309 </p> 310 </dd> 311 <dt><span><code>--program-transform-name=<var>pattern</var></code></span></dt> 312 <dd><p>Applies the ‘<samp>sed</samp>’ script <var>pattern</var> to be applied to the names 313 of programs to install in <var>bindir</var> (see above). <var>pattern</var> has to 314 consist of one or more basic ‘<samp>sed</samp>’ editing commands, separated by 315 semicolons. For example, if you want the ‘<samp>gcc</samp>’ program name to be 316 transformed to the installed program <samp>/usr/local/bin/myowngcc</samp> and 317 the ‘<samp>g++</samp>’ program name to be transformed to 318 <samp>/usr/local/bin/gspecial++</samp> without changing other program names, 319 you could use the pattern 320 <samp>--program-transform-name='s/^gcc$/myowngcc/; s/^g++$/gspecial++/'</samp> 321 to achieve this effect. 322 </p> 323 <p>All three options can be combined and used together, resulting in more 324 complex conversion patterns. As a basic rule, <var>prefix</var> (and 325 <var>suffix</var>) are prepended (appended) before further transformations 326 can happen with a special transformation script <var>pattern</var>. 327 </p> 328 <p>As currently implemented, this option only takes effect for native 329 builds; cross compiler binaries’ names are not transformed even when a 330 transformation is explicitly asked for by one of these options. 331 </p> 332 <p>For native builds, some of the installed programs are also installed 333 with the target alias in front of their name, as in 334 ‘<samp>i686-pc-linux-gnu-gcc</samp>’. All of the above transformations happen 335 before the target alias is prepended to the name—so, specifying 336 <samp>--program-prefix=foo-</samp> and <samp>program-suffix=-3.1</samp>, the 337 resulting binary would be installed as 338 <samp>/usr/local/bin/i686-pc-linux-gnu-foo-gcc-3.1</samp>. 339 </p> 340 <p>As a last shortcoming, none of the installed Ada programs are 341 transformed yet, which will be fixed in some time. 342 </p> 343 </dd> 344 <dt><span><code>--with-local-prefix=<var>dirname</var></code></span></dt> 345 <dd><p>Specify the 346 installation directory for local include files. The default is 347 <samp>/usr/local</samp>. Specify this option if you want the compiler to 348 search directory <samp><var>dirname</var>/include</samp> for locally installed 349 header files <em>instead</em> of <samp>/usr/local/include</samp>. 350 </p> 351 <p>You should specify <samp>--with-local-prefix</samp> <strong>only</strong> if your 352 site has a different convention (not <samp>/usr/local</samp>) for where to put 353 site-specific files. 354 </p> 355 <p>The default value for <samp>--with-local-prefix</samp> is <samp>/usr/local</samp> 356 regardless of the value of <samp>--prefix</samp>. Specifying 357 <samp>--prefix</samp> has no effect on which directory GCC searches for 358 local header files. This may seem counterintuitive, but actually it is 359 logical. 360 </p> 361 <p>The purpose of <samp>--prefix</samp> is to specify where to <em>install 362 GCC</em>. The local header files in <samp>/usr/local/include</samp>—if you put 363 any in that directory—are not part of GCC. They are part of other 364 programs—perhaps many others. (GCC installs its own header files in 365 another directory which is based on the <samp>--prefix</samp> value.) 366 </p> 367 <p>Both the local-prefix include directory and the GCC-prefix include 368 directory are part of GCC’s “system include” directories. Although these 369 two directories are not fixed, they need to be searched in the proper 370 order for the correct processing of the include_next directive. The 371 local-prefix include directory is searched before the GCC-prefix 372 include directory. Another characteristic of system include directories 373 is that pedantic warnings are turned off for headers in these directories. 374 </p> 375 <p>Some autoconf macros add <samp>-I <var>directory</var></samp> options to the 376 compiler command line, to ensure that directories containing installed 377 packages’ headers are searched. When <var>directory</var> is one of GCC’s 378 system include directories, GCC will ignore the option so that system 379 directories continue to be processed in the correct order. This 380 may result in a search order different from what was specified but the 381 directory will still be searched. 382 </p> 383 <p>GCC automatically searches for ordinary libraries using 384 <code>GCC_EXEC_PREFIX</code>. Thus, when the same installation prefix is 385 used for both GCC and packages, GCC will automatically search for 386 both headers and libraries. This provides a configuration that is 387 easy to use. GCC behaves in a manner similar to that when it is 388 installed as a system compiler in <samp>/usr</samp>. 389 </p> 390 <p>Sites that need to install multiple versions of GCC may not want to 391 use the above simple configuration. It is possible to use the 392 <samp>--program-prefix</samp>, <samp>--program-suffix</samp> and 393 <samp>--program-transform-name</samp> options to install multiple versions 394 into a single directory, but it may be simpler to use different prefixes 395 and the <samp>--with-local-prefix</samp> option to specify the location of the 396 site-specific files for each version. It will then be necessary for 397 users to specify explicitly the location of local site libraries 398 (e.g., with <code>LIBRARY_PATH</code>). 399 </p> 400 <p>The same value can be used for both <samp>--with-local-prefix</samp> and 401 <samp>--prefix</samp> provided it is not <samp>/usr</samp>. This can be used 402 to avoid the default search of <samp>/usr/local/include</samp>. 403 </p> 404 <p><strong>Do not</strong> specify <samp>/usr</samp> as the <samp>--with-local-prefix</samp>! 405 The directory you use for <samp>--with-local-prefix</samp> <strong>must not</strong> 406 contain any of the system’s standard header files. If it did contain 407 them, certain programs would be miscompiled (including GNU Emacs, on 408 certain targets), because this would override and nullify the header 409 file corrections made by the <code>fixincludes</code> script. 410 </p> 411 <p>Indications are that people who use this option use it based on mistaken 412 ideas of what it is for. People use it as if it specified where to 413 install part of GCC. Perhaps they make this assumption because 414 installing GCC creates the directory. 415 </p> 416 </dd> 417 <dt><span><code>--with-gcc-major-version-only</code></span></dt> 418 <dd><p>Specifies that GCC should use only the major number rather than 419 <var>major</var>.<var>minor</var>.<var>patchlevel</var> in filesystem paths. 420 </p> 421 </dd> 422 <dt><span><code>--with-native-system-header-dir=<var>dirname</var></code></span></dt> 423 <dd><p>Specifies that <var>dirname</var> is the directory that contains native system 424 header files, rather than <samp>/usr/include</samp>. This option is most useful 425 if you are creating a compiler that should be isolated from the system 426 as much as possible. It is most commonly used with the 427 <samp>--with-sysroot</samp> option and will cause GCC to search 428 <var>dirname</var> inside the system root specified by that option. 429 </p> 430 </dd> 431 <dt><span><code>--enable-shared[=<var>package</var>[,…]]</code></span></dt> 432 <dd><p>Build shared versions of libraries, if shared libraries are supported on 433 the target platform. Unlike GCC 2.95.x and earlier, shared libraries 434 are enabled by default on all platforms that support shared libraries. 435 </p> 436 <p>If a list of packages is given as an argument, build shared libraries 437 only for the listed packages. For other packages, only static libraries 438 will be built. Package names currently recognized in the GCC tree are 439 ‘<samp>libgcc</samp>’ (also known as ‘<samp>gcc</samp>’), ‘<samp>libstdc++</samp>’ (not 440 ‘<samp>libstdc++-v3</samp>’), ‘<samp>libffi</samp>’, ‘<samp>zlib</samp>’, ‘<samp>boehm-gc</samp>’, 441 ‘<samp>ada</samp>’, ‘<samp>libada</samp>’, ‘<samp>libgo</samp>’, ‘<samp>libobjc</samp>’, and ‘<samp>libphobos</samp>’. 442 Note ‘<samp>libiberty</samp>’ does not support shared libraries at all. 443 </p> 444 <p>Use <samp>--disable-shared</samp> to build only static libraries. Note that 445 <samp>--disable-shared</samp> does not accept a list of package names as 446 argument, only <samp>--enable-shared</samp> does. 447 </p> 448 <p>Contrast with <samp>--enable-host-shared</samp>, which affects <em>host</em> 449 code. 450 </p> 451 </dd> 452 <dt><span><code>--enable-host-shared</code></span></dt> 453 <dd><p>Specify that the <em>host</em> code should be built into position-independent 454 machine code (with -fPIC), allowing it to be used within shared libraries, 455 but yielding a slightly slower compiler. 456 </p> 457 <p>This option is required when building the libgccjit.so library. 458 </p> 459 <p>Contrast with <samp>--enable-shared</samp>, which affects <em>target</em> 460 libraries. 461 </p> 462 </dd> 463 <dt><span><code><span id="with-gnu-as"></span>--with-gnu-as</code></span></dt> 464 <dd><p>Specify that the compiler should assume that the 465 assembler it finds is the GNU assembler. However, this does not modify 466 the rules to find an assembler and will result in confusion if the 467 assembler found is not actually the GNU assembler. (Confusion may also 468 result if the compiler finds the GNU assembler but has not been 469 configured with <samp>--with-gnu-as</samp>.) If you have more than one 470 assembler installed on your system, you may want to use this option in 471 connection with <samp>--with-as=<var>pathname</var></samp> or 472 <samp>--with-build-time-tools=<var>pathname</var></samp>. 473 </p> 474 <p>The following systems are the only ones where it makes a difference 475 whether you use the GNU assembler. On any other system, 476 <samp>--with-gnu-as</samp> has no effect. 477 </p> 478 <ul> 479 <li> ‘<samp>hppa1.0-<var>any</var>-<var>any</var></samp>’ 480 </li><li> ‘<samp>hppa1.1-<var>any</var>-<var>any</var></samp>’ 481 </li><li> ‘<samp>sparc-sun-solaris2.<var>any</var></samp>’ 482 </li><li> ‘<samp>sparc64-<var>any</var>-solaris2.<var>any</var></samp>’ 483 </li></ul> 484 485 </dd> 486 <dt><span><code><span id="with-as"></span>--with-as=<var>pathname</var></code></span></dt> 487 <dd><p>Specify that the compiler should use the assembler pointed to by 488 <var>pathname</var>, rather than the one found by the standard rules to find 489 an assembler, which are: 490 </p><ul> 491 <li> Unless GCC is being built with a cross compiler, check the 492 <samp><var>libexec</var>/gcc/<var>target</var>/<var>version</var></samp> directory. 493 <var>libexec</var> defaults to <samp><var>exec-prefix</var>/libexec</samp>; 494 <var>exec-prefix</var> defaults to <var>prefix</var>, which 495 defaults to <samp>/usr/local</samp> unless overridden by the 496 <samp>--prefix=<var>pathname</var></samp> switch described above. <var>target</var> 497 is the target system triple, such as ‘<samp>sparc-sun-solaris2.7</samp>’, and 498 <var>version</var> denotes the GCC version, such as 3.0. 499 500 </li><li> If the target system is the same that you are building on, check 501 operating system specific directories (e.g. <samp>/usr/ccs/bin</samp> on 502 Solaris 2). 503 504 </li><li> Check in the <code>PATH</code> for a tool whose name is prefixed by the 505 target system triple. 506 507 </li><li> Check in the <code>PATH</code> for a tool whose name is not prefixed by the 508 target system triple, if the host and target system triple are 509 the same (in other words, we use a host tool if it can be used for 510 the target as well). 511 </li></ul> 512 513 <p>You may want to use <samp>--with-as</samp> if no assembler 514 is installed in the directories listed above, or if you have multiple 515 assemblers installed and want to choose one that is not found by the 516 above rules. 517 </p> 518 </dd> 519 <dt><span><code><span id="with-gnu-ld"></span>--with-gnu-ld</code></span></dt> 520 <dd><p>Same as <a href="#with-gnu-as"><samp>--with-gnu-as</samp></a> 521 but for the linker. 522 </p> 523 </dd> 524 <dt><span><code>--with-ld=<var>pathname</var></code></span></dt> 525 <dd><p>Same as <a href="#with-as"><samp>--with-as</samp></a> 526 but for the linker. 527 </p> 528 </dd> 529 <dt><span><code>--with-dsymutil=<var>pathname</var></code></span></dt> 530 <dd><p>Same as <a href="#with-as"><samp>--with-as</samp></a> 531 but for the debug linker (only used on Darwin platforms so far). 532 </p> 533 </dd> 534 <dt><span><code>--with-stabs</code></span></dt> 535 <dd><p>Specify that stabs debugging 536 information should be used instead of whatever format the host normally 537 uses. Normally GCC uses the same debug format as the host system. 538 </p> 539 </dd> 540 <dt><span><code>--with-tls=<var>dialect</var></code></span></dt> 541 <dd><p>Specify the default TLS dialect, for systems were there is a choice. 542 For ARM targets, possible values for <var>dialect</var> are <code>gnu</code> or 543 <code>gnu2</code>, which select between the original GNU dialect and the GNU TLS 544 descriptor-based dialect. 545 </p> 546 </dd> 547 <dt><span><code>--enable-multiarch</code></span></dt> 548 <dd><p>Specify whether to enable or disable multiarch support. The default is 549 to check for glibc start files in a multiarch location, and enable it 550 if the files are found. The auto detection is enabled for native builds, 551 and for cross builds configured with <samp>--with-sysroot</samp>, and without 552 <samp>--with-native-system-header-dir</samp>. 553 More documentation about multiarch can be found at 554 <a href="https://wiki.debian.org/Multiarch">https://wiki.debian.org/Multiarch</a>. 555 </p> 556 </dd> 557 <dt><span><code>--enable-sjlj-exceptions</code></span></dt> 558 <dd><p>Force use of the <code>setjmp</code>/<code>longjmp</code>-based scheme for exceptions. 559 ‘<samp>configure</samp>’ ordinarily picks the correct value based on the platform. 560 Only use this option if you are sure you need a different setting. 561 </p> 562 </dd> 563 <dt><span><code>--enable-vtable-verify</code></span></dt> 564 <dd><p>Specify whether to enable or disable the vtable verification feature. 565 Enabling this feature causes libstdc++ to be built with its virtual calls 566 in verifiable mode. This means that, when linked with libvtv, every 567 virtual call in libstdc++ will verify the vtable pointer through which the 568 call will be made before actually making the call. If not linked with libvtv, 569 the verifier will call stub functions (in libstdc++ itself) and do nothing. 570 If vtable verification is disabled, then libstdc++ is not built with its 571 virtual calls in verifiable mode at all. However the libvtv library will 572 still be built (see <samp>--disable-libvtv</samp> to turn off building libvtv). 573 <samp>--disable-vtable-verify</samp> is the default. 574 </p> 575 </dd> 576 <dt><span><code>--disable-gcov</code></span></dt> 577 <dd><p>Specify that the run-time library used for coverage analysis 578 and associated host tools should not be built. 579 </p> 580 </dd> 581 <dt><span><code>--disable-multilib</code></span></dt> 582 <dd><p>Specify that multiple target 583 libraries to support different target variants, calling 584 conventions, etc. should not be built. The default is to build a 585 predefined set of them. 586 </p> 587 <p>Some targets provide finer-grained control over which multilibs are built 588 (e.g., <samp>--disable-softfloat</samp>): 589 </p><dl compact="compact"> 590 <dt><span><code>arm-*-*</code></span></dt> 591 <dd><p>fpu, 26bit, underscore, interwork, biendian, nofmult. 592 </p> 593 </dd> 594 <dt><span><code>m68*-*-*</code></span></dt> 595 <dd><p>softfloat, m68881, m68000, m68020. 596 </p> 597 </dd> 598 <dt><span><code>mips*-*-*</code></span></dt> 599 <dd><p>single-float, biendian, softfloat. 600 </p> 601 </dd> 602 <dt><span><code>msp430-*-*</code></span></dt> 603 <dd><p>no-exceptions 604 </p> 605 </dd> 606 <dt><span><code>powerpc*-*-*, rs6000*-*-*</code></span></dt> 607 <dd><p>aix64, pthread, softfloat, powercpu, powerpccpu, powerpcos, biendian, 608 sysv, aix. 609 </p> 610 </dd> 611 </dl> 612 613 </dd> 614 <dt><span><code>--with-multilib-list=<var>list</var></code></span></dt> 615 <dt><span><code>--without-multilib-list</code></span></dt> 616 <dd><p>Specify what multilibs to build. <var>list</var> is a comma separated list of 617 values, possibly consisting of a single value. Currently only implemented 618 for aarch64*-*-*, arm*-*-*, riscv*-*-*, sh*-*-* and x86-64-*-linux*. The 619 accepted values and meaning for each target is given below. 620 </p> 621 <dl compact="compact"> 622 <dt><span><code>aarch64*-*-*</code></span></dt> 623 <dd><p><var>list</var> is a comma separated list of <code>ilp32</code>, and <code>lp64</code> 624 to enable ILP32 and LP64 run-time libraries, respectively. If 625 <var>list</var> is empty, then there will be no multilibs and only the 626 default run-time library will be built. If <var>list</var> is 627 <code>default</code> or –with-multilib-list= is not specified, then the 628 default set of libraries is selected based on the value of 629 <samp>--target</samp>. 630 </p> 631 </dd> 632 <dt><span><code>arm*-*-*</code></span></dt> 633 <dd><p><var>list</var> is a comma separated list of <code>aprofile</code> and 634 <code>rmprofile</code> to build multilibs for A or R and M architecture 635 profiles respectively. Note that, due to some limitation of the current 636 multilib framework, using the combined <code>aprofile,rmprofile</code> 637 multilibs selects in some cases a less optimal multilib than when using 638 the multilib profile for the architecture targetted. The special value 639 <code>default</code> is also accepted and is equivalent to omitting the 640 option, i.e., only the default run-time library will be enabled. 641 </p> 642 <p><var>list</var> may instead contain <code>@name</code>, to use the multilib 643 configuration Makefile fragment <samp>name</samp> in <samp>gcc/config/arm</samp> in 644 the source tree (it is part of the corresponding sources, after all). 645 It is recommended, but not required, that files used for this purpose to 646 be named starting with <samp>t-ml-</samp>, to make their intended purpose 647 self-evident, in line with GCC conventions. Such files enable custom, 648 user-chosen multilib lists to be configured. Whether multiple such 649 files can be used together depends on the contents of the supplied 650 files. See <samp>gcc/config/arm/t-multilib</samp> and its supplementary 651 <samp>gcc/config/arm/t-*profile</samp> files for an example of what such 652 Makefile fragments might look like for this version of GCC. The macros 653 expected to be defined in these fragments are not stable across GCC 654 releases, so make sure they define the <code>MULTILIB</code>-related macros 655 expected by the version of GCC you are building. 656 See “Target Makefile Fragments” in the internals manual. 657 </p> 658 <p>The table below gives the combination of ISAs, architectures, FPUs and 659 floating-point ABIs for which multilibs are built for each predefined 660 profile. The union of these options is considered when specifying both 661 <code>aprofile</code> and <code>rmprofile</code>. 662 </p> 663 <table> 664 <tr><td width="15%">Option</td><td width="28%">aprofile</td><td width="30%">rmprofile</td></tr> 665 <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> 666 <tr><td width="15%">Architectures<br><br><br><br><br><br></td><td width="28%">default architecture<br> 667 <code>-march=armv7-a</code><br> 668 <code>-march=armv7ve</code><br> 669 <code>-march=armv8-a</code><br><br><br></td><td width="30%">default architecture<br> 670 <code>-march=armv6s-m</code><br> 671 <code>-march=armv7-m</code><br> 672 <code>-march=armv7e-m</code><br> 673 <code>-march=armv8-m.base</code><br> 674 <code>-march=armv8-m.main</code><br> 675 <code>-march=armv7</code></td></tr> 676 <tr><td width="15%">FPUs<br><br><br><br><br></td><td width="28%">none<br> 677 <code>-mfpu=vfpv3-d16</code><br> 678 <code>-mfpu=neon</code><br> 679 <code>-mfpu=vfpv4-d16</code><br> 680 <code>-mfpu=neon-vfpv4</code><br> 681 <code>-mfpu=neon-fp-armv8</code></td><td width="30%">none<br> 682 <code>-mfpu=vfpv3-d16</code><br> 683 <code>-mfpu=fpv4-sp-d16</code><br> 684 <code>-mfpu=fpv5-sp-d16</code><br> 685 <code>-mfpu=fpv5-d16</code><br></td></tr> 686 <tr><td width="15%">floating-point ABIs<br><br></td><td width="28%"><code>-mfloat-abi=soft</code><br> 687 <code>-mfloat-abi=softfp</code><br> 688 <code>-mfloat-abi=hard</code></td><td width="30%"><code>-mfloat-abi=soft</code><br> 689 <code>-mfloat-abi=softfp</code><br> 690 <code>-mfloat-abi=hard</code></td></tr> 691 </table> 692 693 </dd> 694 <dt><span><code>riscv*-*-*</code></span></dt> 695 <dd><p><var>list</var> is a single ABI name. The target architecture must be either 696 <code>rv32gc</code> or <code>rv64gc</code>. This will build a single multilib for the 697 specified architecture and ABI pair. If <code>--with-multilib-list</code> is not 698 given, then a default set of multilibs is selected based on the value of 699 <samp>--target</samp>. This is usually a large set of multilibs. 700 </p> 701 </dd> 702 <dt><span><code>sh*-*-*</code></span></dt> 703 <dd><p><var>list</var> is a comma separated list of CPU names. These must be of the 704 form <code>sh*</code> or <code>m*</code> (in which case they match the compiler option 705 for that processor). The list should not contain any endian options - 706 these are handled by <samp>--with-endian</samp>. 707 </p> 708 <p>If <var>list</var> is empty, then there will be no multilibs for extra 709 processors. The multilib for the secondary endian remains enabled. 710 </p> 711 <p>As a special case, if an entry in the list starts with a <code>!</code> 712 (exclamation point), then it is added to the list of excluded multilibs. 713 Entries of this sort should be compatible with ‘<samp>MULTILIB_EXCLUDES</samp>’ 714 (once the leading <code>!</code> has been stripped). 715 </p> 716 <p>If <samp>--with-multilib-list</samp> is not given, then a default set of 717 multilibs is selected based on the value of <samp>--target</samp>. This is 718 usually the complete set of libraries, but some targets imply a more 719 specialized subset. 720 </p> 721 <p>Example 1: to configure a compiler for SH4A only, but supporting both 722 endians, with little endian being the default: 723 </p><div class="example"> 724 <pre class="example">--with-cpu=sh4a --with-endian=little,big --with-multilib-list= 725 </pre></div> 726 727 <p>Example 2: to configure a compiler for both SH4A and SH4AL-DSP, but with 728 only little endian SH4AL: 729 </p><div class="example"> 730 <pre class="example">--with-cpu=sh4a --with-endian=little,big \ 731 --with-multilib-list=sh4al,!mb/m4al 732 </pre></div> 733 734 </dd> 735 <dt><span><code>x86-64-*-linux*</code></span></dt> 736 <dd><p><var>list</var> is a comma separated list of <code>m32</code>, <code>m64</code> and 737 <code>mx32</code> to enable 32-bit, 64-bit and x32 run-time libraries, 738 respectively. If <var>list</var> is empty, then there will be no multilibs 739 and only the default run-time library will be enabled. 740 </p> 741 <p>If <samp>--with-multilib-list</samp> is not given, then only 32-bit and 742 64-bit run-time libraries will be enabled. 743 </p></dd> 744 </dl> 745 746 </dd> 747 <dt><span><code>--with-endian=<var>endians</var></code></span></dt> 748 <dd><p>Specify what endians to use. 749 Currently only implemented for sh*-*-*. 750 </p> 751 <p><var>endians</var> may be one of the following: 752 </p><dl compact="compact"> 753 <dt><span><code>big</code></span></dt> 754 <dd><p>Use big endian exclusively. 755 </p></dd> 756 <dt><span><code>little</code></span></dt> 757 <dd><p>Use little endian exclusively. 758 </p></dd> 759 <dt><span><code>big,little</code></span></dt> 760 <dd><p>Use big endian by default. Provide a multilib for little endian. 761 </p></dd> 762 <dt><span><code>little,big</code></span></dt> 763 <dd><p>Use little endian by default. Provide a multilib for big endian. 764 </p></dd> 765 </dl> 766 767 </dd> 768 <dt><span><code>--enable-threads</code></span></dt> 769 <dd><p>Specify that the target 770 supports threads. This affects the Objective-C compiler and runtime 771 library, and exception handling for other languages like C++. 772 On some systems, this is the default. 773 </p> 774 <p>In general, the best (and, in many cases, the only known) threading 775 model available will be configured for use. Beware that on some 776 systems, GCC has not been taught what threading models are generally 777 available for the system. In this case, <samp>--enable-threads</samp> is an 778 alias for <samp>--enable-threads=single</samp>. 779 </p> 780 </dd> 781 <dt><span><code>--disable-threads</code></span></dt> 782 <dd><p>Specify that threading support should be disabled for the system. 783 This is an alias for <samp>--enable-threads=single</samp>. 784 </p> 785 </dd> 786 <dt><span><code>--enable-threads=<var>lib</var></code></span></dt> 787 <dd><p>Specify that 788 <var>lib</var> is the thread support library. This affects the Objective-C 789 compiler and runtime library, and exception handling for other languages 790 like C++. The possibilities for <var>lib</var> are: 791 </p> 792 <dl compact="compact"> 793 <dt><span><code>aix</code></span></dt> 794 <dd><p>AIX thread support. 795 </p></dd> 796 <dt><span><code>dce</code></span></dt> 797 <dd><p>DCE thread support. 798 </p></dd> 799 <dt><span><code>lynx</code></span></dt> 800 <dd><p>LynxOS thread support. 801 </p></dd> 802 <dt><span><code>mipssde</code></span></dt> 803 <dd><p>MIPS SDE thread support. 804 </p></dd> 805 <dt><span><code>no</code></span></dt> 806 <dd><p>This is an alias for ‘<samp>single</samp>’. 807 </p></dd> 808 <dt><span><code>posix</code></span></dt> 809 <dd><p>Generic POSIX/Unix98 thread support. 810 </p></dd> 811 <dt><span><code>rtems</code></span></dt> 812 <dd><p>RTEMS thread support. 813 </p></dd> 814 <dt><span><code>single</code></span></dt> 815 <dd><p>Disable thread support, should work for all platforms. 816 </p></dd> 817 <dt><span><code>tpf</code></span></dt> 818 <dd><p>TPF thread support. 819 </p></dd> 820 <dt><span><code>vxworks</code></span></dt> 821 <dd><p>VxWorks thread support. 822 </p></dd> 823 <dt><span><code>win32</code></span></dt> 824 <dd><p>Microsoft Win32 API thread support. 825 </p></dd> 826 </dl> 827 828 </dd> 829 <dt><span><code>--enable-tls</code></span></dt> 830 <dd><p>Specify that the target supports TLS (Thread Local Storage). Usually 831 configure can correctly determine if TLS is supported. In cases where 832 it guesses incorrectly, TLS can be explicitly enabled or disabled with 833 <samp>--enable-tls</samp> or <samp>--disable-tls</samp>. This can happen if 834 the assembler supports TLS but the C library does not, or if the 835 assumptions made by the configure test are incorrect. 836 </p> 837 </dd> 838 <dt><span><code>--disable-tls</code></span></dt> 839 <dd><p>Specify that the target does not support TLS. 840 This is an alias for <samp>--enable-tls=no</samp>. 841 </p> 842 </dd> 843 <dt><span><code>--disable-tm-clone-registry</code></span></dt> 844 <dd><p>Disable TM clone registry in libgcc. It is enabled in libgcc by default. 845 This option helps to reduce code size for embedded targets which do 846 not use transactional memory. 847 </p> 848 </dd> 849 <dt><span><code>--with-cpu=<var>cpu</var></code></span></dt> 850 <dt><span><code>--with-cpu-32=<var>cpu</var></code></span></dt> 851 <dt><span><code>--with-cpu-64=<var>cpu</var></code></span></dt> 852 <dd><p>Specify which cpu variant the compiler should generate code for by default. 853 <var>cpu</var> will be used as the default value of the <samp>-mcpu=</samp> switch. 854 This option is only supported on some targets, including ARC, ARM, i386, M68k, 855 PowerPC, and SPARC. It is mandatory for ARC. The <samp>--with-cpu-32</samp> and 856 <samp>--with-cpu-64</samp> options specify separate default CPUs for 857 32-bit and 64-bit modes; these options are only supported for aarch64, i386, 858 x86-64, PowerPC, and SPARC. 859 </p> 860 </dd> 861 <dt><span><code>--with-schedule=<var>cpu</var></code></span></dt> 862 <dt><span><code>--with-arch=<var>cpu</var></code></span></dt> 863 <dt><span><code>--with-arch-32=<var>cpu</var></code></span></dt> 864 <dt><span><code>--with-arch-64=<var>cpu</var></code></span></dt> 865 <dt><span><code>--with-tune=<var>cpu</var></code></span></dt> 866 <dt><span><code>--with-tune-32=<var>cpu</var></code></span></dt> 867 <dt><span><code>--with-tune-64=<var>cpu</var></code></span></dt> 868 <dt><span><code>--with-abi=<var>abi</var></code></span></dt> 869 <dt><span><code>--with-fpu=<var>type</var></code></span></dt> 870 <dt><span><code>--with-float=<var>type</var></code></span></dt> 871 <dd><p>These configure options provide default values for the <samp>-mschedule=</samp>, 872 <samp>-march=</samp>, <samp>-mtune=</samp>, <samp>-mabi=</samp>, and <samp>-mfpu=</samp> 873 options and for <samp>-mhard-float</samp> or <samp>-msoft-float</samp>. As with 874 <samp>--with-cpu</samp>, which switches will be accepted and acceptable values 875 of the arguments depend on the target. 876 </p> 877 </dd> 878 <dt><span><code>--with-mode=<var>mode</var></code></span></dt> 879 <dd><p>Specify if the compiler should default to <samp>-marm</samp> or <samp>-mthumb</samp>. 880 This option is only supported on ARM targets. 881 </p> 882 </dd> 883 <dt><span><code>--with-stack-offset=<var>num</var></code></span></dt> 884 <dd><p>This option sets the default for the -mstack-offset=<var>num</var> option, 885 and will thus generally also control the setting of this option for 886 libraries. This option is only supported on Epiphany targets. 887 </p> 888 </dd> 889 <dt><span><code>--with-fpmath=<var>isa</var></code></span></dt> 890 <dd><p>This options sets <samp>-mfpmath=sse</samp> by default and specifies the default 891 ISA for floating-point arithmetics. You can select either ‘<samp>sse</samp>’ which 892 enables <samp>-msse2</samp> or ‘<samp>avx</samp>’ which enables <samp>-mavx</samp> by default. 893 This option is only supported on i386 and x86-64 targets. 894 </p> 895 </dd> 896 <dt><span><code>--with-fp-32=<var>mode</var></code></span></dt> 897 <dd><p>On MIPS targets, set the default value for the <samp>-mfp</samp> option when using 898 the o32 ABI. The possibilities for <var>mode</var> are: 899 </p><dl compact="compact"> 900 <dt><span><code>32</code></span></dt> 901 <dd><p>Use the o32 FP32 ABI extension, as with the <samp>-mfp32</samp> command-line 902 option. 903 </p></dd> 904 <dt><span><code>xx</code></span></dt> 905 <dd><p>Use the o32 FPXX ABI extension, as with the <samp>-mfpxx</samp> command-line 906 option. 907 </p></dd> 908 <dt><span><code>64</code></span></dt> 909 <dd><p>Use the o32 FP64 ABI extension, as with the <samp>-mfp64</samp> command-line 910 option. 911 </p></dd> 912 </dl> 913 <p>In the absence of this configuration option the default is to use the o32 914 FP32 ABI extension. 915 </p> 916 </dd> 917 <dt><span><code>--with-odd-spreg-32</code></span></dt> 918 <dd><p>On MIPS targets, set the <samp>-modd-spreg</samp> option by default when using 919 the o32 ABI. 920 </p> 921 </dd> 922 <dt><span><code>--without-odd-spreg-32</code></span></dt> 923 <dd><p>On MIPS targets, set the <samp>-mno-odd-spreg</samp> option by default when using 924 the o32 ABI. This is normally used in conjunction with 925 <samp>--with-fp-32=64</samp> in order to target the o32 FP64A ABI extension. 926 </p> 927 </dd> 928 <dt><span><code>--with-nan=<var>encoding</var></code></span></dt> 929 <dd><p>On MIPS targets, set the default encoding convention to use for the 930 special not-a-number (NaN) IEEE 754 floating-point data. The 931 possibilities for <var>encoding</var> are: 932 </p><dl compact="compact"> 933 <dt><span><code>legacy</code></span></dt> 934 <dd><p>Use the legacy encoding, as with the <samp>-mnan=legacy</samp> command-line 935 option. 936 </p></dd> 937 <dt><span><code>2008</code></span></dt> 938 <dd><p>Use the 754-2008 encoding, as with the <samp>-mnan=2008</samp> command-line 939 option. 940 </p></dd> 941 </dl> 942 <p>To use this configuration option you must have an assembler version 943 installed that supports the <samp>-mnan=</samp> command-line option too. 944 In the absence of this configuration option the default convention is 945 the legacy encoding, as when neither of the <samp>-mnan=2008</samp> and 946 <samp>-mnan=legacy</samp> command-line options has been used. 947 </p> 948 </dd> 949 <dt><span><code>--with-divide=<var>type</var></code></span></dt> 950 <dd><p>Specify how the compiler should generate code for checking for 951 division by zero. This option is only supported on the MIPS target. 952 The possibilities for <var>type</var> are: 953 </p><dl compact="compact"> 954 <dt><span><code>traps</code></span></dt> 955 <dd><p>Division by zero checks use conditional traps (this is the default on 956 systems that support conditional traps). 957 </p></dd> 958 <dt><span><code>breaks</code></span></dt> 959 <dd><p>Division by zero checks use the break instruction. 960 </p></dd> 961 </dl> 962 963 964 </dd> 965 <dt><span><code>--with-llsc</code></span></dt> 966 <dd><p>On MIPS targets, make <samp>-mllsc</samp> the default when no 967 <samp>-mno-llsc</samp> option is passed. This is the default for 968 Linux-based targets, as the kernel will emulate them if the ISA does 969 not provide them. 970 </p> 971 </dd> 972 <dt><span><code>--without-llsc</code></span></dt> 973 <dd><p>On MIPS targets, make <samp>-mno-llsc</samp> the default when no 974 <samp>-mllsc</samp> option is passed. 975 </p> 976 </dd> 977 <dt><span><code>--with-synci</code></span></dt> 978 <dd><p>On MIPS targets, make <samp>-msynci</samp> the default when no 979 <samp>-mno-synci</samp> option is passed. 980 </p> 981 </dd> 982 <dt><span><code>--without-synci</code></span></dt> 983 <dd><p>On MIPS targets, make <samp>-mno-synci</samp> the default when no 984 <samp>-msynci</samp> option is passed. This is the default. 985 </p> 986 </dd> 987 <dt><span><code>--with-lxc1-sxc1</code></span></dt> 988 <dd><p>On MIPS targets, make <samp>-mlxc1-sxc1</samp> the default when no 989 <samp>-mno-lxc1-sxc1</samp> option is passed. This is the default. 990 </p> 991 </dd> 992 <dt><span><code>--without-lxc1-sxc1</code></span></dt> 993 <dd><p>On MIPS targets, make <samp>-mno-lxc1-sxc1</samp> the default when no 994 <samp>-mlxc1-sxc1</samp> option is passed. The indexed load/store 995 instructions are not directly a problem but can lead to unexpected 996 behaviour when deployed in an application intended for a 32-bit address 997 space but run on a 64-bit processor. The issue is seen because all 998 known MIPS 64-bit Linux kernels execute o32 and n32 applications 999 with 64-bit addressing enabled which affects the overflow behaviour 1000 of the indexed addressing mode. GCC will assume that ordinary 1001 32-bit arithmetic overflow behaviour is the same whether performed 1002 as an <code>addu</code> instruction or as part of the address calculation 1003 in <code>lwxc1</code> type instructions. This assumption holds true in a 1004 pure 32-bit environment and can hold true in a 64-bit environment if 1005 the address space is accurately set to be 32-bit for o32 and n32. 1006 </p> 1007 </dd> 1008 <dt><span><code>--with-madd4</code></span></dt> 1009 <dd><p>On MIPS targets, make <samp>-mmadd4</samp> the default when no 1010 <samp>-mno-madd4</samp> option is passed. This is the default. 1011 </p> 1012 </dd> 1013 <dt><span><code>--without-madd4</code></span></dt> 1014 <dd><p>On MIPS targets, make <samp>-mno-madd4</samp> the default when no 1015 <samp>-mmadd4</samp> option is passed. The <code>madd4</code> instruction 1016 family can be problematic when targeting a combination of cores that 1017 implement these instructions differently. There are two known cores 1018 that implement these as fused operations instead of unfused (where 1019 unfused is normally expected). Disabling these instructions is the 1020 only way to ensure compatible code is generated; this will incur 1021 a performance penalty. 1022 </p> 1023 </dd> 1024 <dt><span><code>--with-mips-plt</code></span></dt> 1025 <dd><p>On MIPS targets, make use of copy relocations and PLTs. 1026 These features are extensions to the traditional 1027 SVR4-based MIPS ABIs and require support from GNU binutils 1028 and the runtime C library. 1029 </p> 1030 </dd> 1031 <dt><span><code>--with-stack-clash-protection-guard-size=<var>size</var></code></span></dt> 1032 <dd><p>On certain targets this option sets the default stack clash protection guard 1033 size as a power of two in bytes. On AArch64 <var>size</var> is required to be either 1034 12 (4KB) or 16 (64KB). 1035 </p> 1036 </dd> 1037 <dt><span><code>--enable-__cxa_atexit</code></span></dt> 1038 <dd><p>Define if you want to use __cxa_atexit, rather than atexit, to 1039 register C++ destructors for local statics and global objects. 1040 This is essential for fully standards-compliant handling of 1041 destructors, but requires __cxa_atexit in libc. This option is currently 1042 only available on systems with GNU libc. When enabled, this will cause 1043 <samp>-fuse-cxa-atexit</samp> to be passed by default. 1044 </p> 1045 </dd> 1046 <dt><span><code>--enable-gnu-indirect-function</code></span></dt> 1047 <dd><p>Define if you want to enable the <code>ifunc</code> attribute. This option is 1048 currently only available on systems with GNU libc on certain targets. 1049 </p> 1050 </dd> 1051 <dt><span><code>--enable-target-optspace</code></span></dt> 1052 <dd><p>Specify that target 1053 libraries should be optimized for code space instead of code speed. 1054 This is the default for the m32r platform. 1055 </p> 1056 </dd> 1057 <dt><span><code>--with-cpp-install-dir=<var>dirname</var></code></span></dt> 1058 <dd><p>Specify that the user visible <code>cpp</code> program should be installed 1059 in <samp><var>prefix</var>/<var>dirname</var>/cpp</samp>, in addition to <var>bindir</var>. 1060 </p> 1061 </dd> 1062 <dt><span><code>--enable-comdat</code></span></dt> 1063 <dd><p>Enable COMDAT group support. This is primarily used to override the 1064 automatically detected value. 1065 </p> 1066 </dd> 1067 <dt><span><code>--enable-initfini-array</code></span></dt> 1068 <dd><p>Force the use of sections <code>.init_array</code> and <code>.fini_array</code> 1069 (instead of <code>.init</code> and <code>.fini</code>) for constructors and 1070 destructors. Option <samp>--disable-initfini-array</samp> has the 1071 opposite effect. If neither option is specified, the configure script 1072 will try to guess whether the <code>.init_array</code> and 1073 <code>.fini_array</code> sections are supported and, if they are, use them. 1074 </p> 1075 </dd> 1076 <dt><span><code>--enable-link-mutex</code></span></dt> 1077 <dd><p>When building GCC, use a mutex to avoid linking the compilers for 1078 multiple languages at the same time, to avoid thrashing on build 1079 systems with limited free memory. The default is not to use such a mutex. 1080 </p> 1081 </dd> 1082 <dt><span><code>--enable-maintainer-mode</code></span></dt> 1083 <dd><p>The build rules that regenerate the Autoconf and Automake output files as 1084 well as the GCC master message catalog <samp>gcc.pot</samp> are normally 1085 disabled. This is because it can only be rebuilt if the complete source 1086 tree is present. If you have changed the sources and want to rebuild the 1087 catalog, configuring with <samp>--enable-maintainer-mode</samp> will enable 1088 this. Note that you need a recent version of the <code>gettext</code> tools 1089 to do so. 1090 </p> 1091 </dd> 1092 <dt><span><code>--disable-bootstrap</code></span></dt> 1093 <dd><p>For a native build, the default configuration is to perform 1094 a 3-stage bootstrap of the compiler when ‘<samp>make</samp>’ is invoked, 1095 testing that GCC can compile itself correctly. If you want to disable 1096 this process, you can configure with <samp>--disable-bootstrap</samp>. 1097 </p> 1098 </dd> 1099 <dt><span><code>--enable-bootstrap</code></span></dt> 1100 <dd><p>In special cases, you may want to perform a 3-stage build 1101 even if the target and host triplets are different. 1102 This is possible when the host can run code compiled for 1103 the target (e.g. host is i686-linux, target is i486-linux). 1104 Starting from GCC 4.2, to do this you have to configure explicitly 1105 with <samp>--enable-bootstrap</samp>. 1106 </p> 1107 </dd> 1108 <dt><span><code>--enable-generated-files-in-srcdir</code></span></dt> 1109 <dd><p>Neither the .c and .h files that are generated from Bison and flex nor the 1110 info manuals and man pages that are built from the .texi files are present 1111 in the repository development tree. When building GCC from that development tree, 1112 or from one of our snapshots, those generated files are placed in your 1113 build directory, which allows for the source to be in a readonly 1114 directory. 1115 </p> 1116 <p>If you configure with <samp>--enable-generated-files-in-srcdir</samp> then those 1117 generated files will go into the source directory. This is mainly intended 1118 for generating release or prerelease tarballs of the GCC sources, since it 1119 is not a requirement that the users of source releases to have flex, Bison, 1120 or makeinfo. 1121 </p> 1122 </dd> 1123 <dt><span><code>--enable-version-specific-runtime-libs</code></span></dt> 1124 <dd><p>Specify 1125 that runtime libraries should be installed in the compiler specific 1126 subdirectory (<samp><var>libdir</var>/gcc</samp>) rather than the usual places. In 1127 addition, ‘<samp>libstdc++</samp>’’s include files will be installed into 1128 <samp><var>libdir</var></samp> unless you overruled it by using 1129 <samp>--with-gxx-include-dir=<var>dirname</var></samp>. Using this option is 1130 particularly useful if you intend to use several versions of GCC in 1131 parallel. The default is ‘<samp>yes</samp>’ for ‘<samp>libada</samp>’, and ‘<samp>no</samp>’ for 1132 the remaining libraries. 1133 </p> 1134 </dd> 1135 <dt><span><code><span id="WithAixSoname"></span>--with-aix-soname=‘<samp>aix</samp>’, ‘<samp>svr4</samp>’ or ‘<samp>both</samp>’</code></span></dt> 1136 <dd><p>Traditional AIX shared library versioning (versioned <code>Shared Object</code> 1137 files as members of unversioned <code>Archive Library</code> files named 1138 ‘<samp>lib.a</samp>’) causes numerous headaches for package managers. However, 1139 <code>Import Files</code> as members of <code>Archive Library</code> files allow for 1140 <strong>filename-based versioning</strong> of shared libraries as seen on Linux/SVR4, 1141 where this is called the "SONAME". But as they prevent static linking, 1142 <code>Import Files</code> may be used with <code>Runtime Linking</code> only, where the 1143 linker does search for ‘<samp>libNAME.so</samp>’ before ‘<samp>libNAME.a</samp>’ library 1144 filenames with the ‘<samp>-lNAME</samp>’ linker flag. 1145 </p> 1146 <span id="AixLdCommand"></span><p>For detailed information please refer to the AIX 1147 <a href="https://www.ibm.com/support/knowledgecenter/search/%22the%20ld%20command%2C%20also%20called%20the%20linkage%20editor%20or%20binder%22">ld 1148 Command</a> reference. 1149 </p> 1150 <p>As long as shared library creation is enabled, upon: 1151 </p><dl compact="compact"> 1152 <dt><span><code>--with-aix-soname=aix</code></span></dt> 1153 <dt><span><code>--with-aix-soname=both</code></span></dt> 1154 <dd><p>A (traditional AIX) <code>Shared Archive Library</code> file is created: 1155 </p><ul> 1156 <li> using the ‘<samp>libNAME.a</samp>’ filename scheme 1157 </li><li> with the <code>Shared Object</code> file as archive member named 1158 ‘<samp>libNAME.so.V</samp>’ (except for ‘<samp>libgcc_s</samp>’, where the <code>Shared 1159 Object</code> file is named ‘<samp>shr.o</samp>’ for backwards compatibility), which 1160 <ul class="no-bullet"> 1161 <li>- is used for runtime loading from inside the ‘<samp>libNAME.a</samp>’ file 1162 </li><li>- is used for dynamic loading via 1163 <code>dlopen("libNAME.a(libNAME.so.V)", RTLD_MEMBER)</code> 1164 </li><li>- is used for shared linking 1165 </li><li>- is used for static linking, so no separate <code>Static Archive 1166 Library</code> file is needed 1167 </li></ul> 1168 </li></ul> 1169 </dd> 1170 <dt><span><code>--with-aix-soname=both</code></span></dt> 1171 <dt><span><code>--with-aix-soname=svr4</code></span></dt> 1172 <dd><p>A (second) <code>Shared Archive Library</code> file is created: 1173 </p><ul> 1174 <li> using the ‘<samp>libNAME.so.V</samp>’ filename scheme 1175 </li><li> with the <code>Shared Object</code> file as archive member named 1176 ‘<samp>shr.o</samp>’, which 1177 <ul class="no-bullet"> 1178 <li>- is created with the <code>-G linker flag</code> 1179 </li><li>- has the <code>F_LOADONLY</code> flag set 1180 </li><li>- is used for runtime loading from inside the ‘<samp>libNAME.so.V</samp>’ file 1181 </li><li>- is used for dynamic loading via <code>dlopen("libNAME.so.V(shr.o)", 1182 RTLD_MEMBER)</code> 1183 </li></ul> 1184 </li><li> with the <code>Import File</code> as archive member named ‘<samp>shr.imp</samp>’, 1185 which 1186 <ul class="no-bullet"> 1187 <li>- refers to ‘<samp>libNAME.so.V(shr.o)</samp>’ as the "SONAME", to be recorded 1188 in the <code>Loader Section</code> of subsequent binaries 1189 </li><li>- indicates whether ‘<samp>libNAME.so.V(shr.o)</samp>’ is 32 or 64 bit 1190 </li><li>- lists all the public symbols exported by ‘<samp>lib.so.V(shr.o)</samp>’, 1191 eventually decorated with the <code>‘<samp>weak</samp>’ Keyword</code> 1192 </li><li>- is necessary for shared linking against ‘<samp>lib.so.V(shr.o)</samp>’ 1193 </li></ul> 1194 </li></ul> 1195 <p>A symbolic link using the ‘<samp>libNAME.so</samp>’ filename scheme is created: 1196 </p><ul> 1197 <li> pointing to the ‘<samp>libNAME.so.V</samp>’ <code>Shared Archive Library</code> file 1198 </li><li> to permit the <code>ld Command</code> to find ‘<samp>lib.so.V(shr.imp)</samp>’ via 1199 the ‘<samp>-lNAME</samp>’ argument (requires <code>Runtime Linking</code> to be enabled) 1200 </li><li> to permit dynamic loading of ‘<samp>lib.so.V(shr.o)</samp>’ without the need 1201 to specify the version number via <code>dlopen("libNAME.so(shr.o)", 1202 RTLD_MEMBER)</code> 1203 </li></ul> 1204 </dd> 1205 </dl> 1206 1207 <p>As long as static library creation is enabled, upon: 1208 </p><dl compact="compact"> 1209 <dt><span><code>--with-aix-soname=svr4</code></span></dt> 1210 <dd><p>A <code>Static Archive Library</code> is created: 1211 </p><ul> 1212 <li> using the ‘<samp>libNAME.a</samp>’ filename scheme 1213 </li><li> with all the <code>Static Object</code> files as archive members, which 1214 <ul class="no-bullet"> 1215 <li>- are used for static linking 1216 </li></ul> 1217 </li></ul> 1218 </dd> 1219 </dl> 1220 1221 <p>While the aix-soname=‘<samp>svr4</samp>’ option does not create <code>Shared Object</code> 1222 files as members of unversioned <code>Archive Library</code> files any more, package 1223 managers still are responsible to 1224 <a href="./specific.html#TransferAixShobj">transfer</a> <code>Shared Object</code> files 1225 found as member of a previously installed unversioned <code>Archive Library</code> 1226 file into the newly installed <code>Archive Library</code> file with the same 1227 filename. 1228 </p> 1229 <p><em>WARNING:</em> Creating <code>Shared Object</code> files with <code>Runtime Linking</code> 1230 enabled may bloat the TOC, eventually leading to <code>TOC overflow</code> errors, 1231 requiring the use of either the <samp>-Wl,-bbigtoc</samp> linker flag (seen to 1232 break with the <code>GDB</code> debugger) or some of the TOC-related compiler flags, 1233 see “RS/6000 and PowerPC Options” in the main manual. 1234 </p> 1235 <p><samp>--with-aix-soname</samp> is currently supported by ‘<samp>libgcc_s</samp>’ only, so 1236 this option is still experimental and not for normal use yet. 1237 </p> 1238 <p>Default is the traditional behavior <samp>--with-aix-soname=‘<samp>aix</samp>’</samp>. 1239 </p> 1240 </dd> 1241 <dt><span><code>--enable-languages=<var>lang1</var>,<var>lang2</var>,…</code></span></dt> 1242 <dd><p>Specify that only a particular subset of compilers and 1243 their runtime libraries should be built. For a list of valid values for 1244 <var>langN</var> you can issue the following command in the 1245 <samp>gcc</samp> directory of your GCC source tree:<br> 1246 </p><div class="example"> 1247 <pre class="example">grep ^language= */config-lang.in 1248 </pre></div> 1249 <p>Currently, you can use any of the following: 1250 <code>all</code>, <code>default</code>, <code>ada</code>, <code>c</code>, <code>c++</code>, <code>d</code>, 1251 <code>fortran</code>, <code>go</code>, <code>jit</code>, <code>lto</code>, <code>objc</code>, <code>obj-c++</code>. 1252 Building the Ada compiler has special requirements, see below. 1253 If you do not pass this flag, or specify the option <code>default</code>, then the 1254 default languages available in the <samp>gcc</samp> sub-tree will be configured. 1255 Ada, D, Go, Jit, and Objective-C++ are not default languages. LTO is not a 1256 default language, but is built by default because <samp>--enable-lto</samp> is 1257 enabled by default. The other languages are default languages. If 1258 <code>all</code> is specified, then all available languages are built. An 1259 exception is <code>jit</code> language, which requires 1260 <samp>--enable-host-shared</samp> to be included with <code>all</code>. 1261 </p> 1262 </dd> 1263 <dt><span><code>--enable-stage1-languages=<var>lang1</var>,<var>lang2</var>,…</code></span></dt> 1264 <dd><p>Specify that a particular subset of compilers and their runtime 1265 libraries should be built with the system C compiler during stage 1 of 1266 the bootstrap process, rather than only in later stages with the 1267 bootstrapped C compiler. The list of valid values is the same as for 1268 <samp>--enable-languages</samp>, and the option <code>all</code> will select all 1269 of the languages enabled by <samp>--enable-languages</samp>. This option is 1270 primarily useful for GCC development; for instance, when a development 1271 version of the compiler cannot bootstrap due to compiler bugs, or when 1272 one is debugging front ends other than the C front end. When this 1273 option is used, one can then build the target libraries for the 1274 specified languages with the stage-1 compiler by using <code>make 1275 stage1-bubble all-target</code>, or run the testsuite on the stage-1 compiler 1276 for the specified languages using <code>make stage1-start check-gcc</code>. 1277 </p> 1278 </dd> 1279 <dt><span><code>--disable-libada</code></span></dt> 1280 <dd><p>Specify that the run-time libraries and tools used by GNAT should not 1281 be built. This can be useful for debugging, or for compatibility with 1282 previous Ada build procedures, when it was required to explicitly 1283 do a ‘<samp>make -C gcc gnatlib_and_tools</samp>’. 1284 </p> 1285 </dd> 1286 <dt><span><code>--disable-libsanitizer</code></span></dt> 1287 <dd><p>Specify that the run-time libraries for the various sanitizers should 1288 not be built. 1289 </p> 1290 </dd> 1291 <dt><span><code>--disable-libssp</code></span></dt> 1292 <dd><p>Specify that the run-time libraries for stack smashing protection 1293 should not be built or linked against. On many targets library support 1294 is provided by the C library instead. 1295 </p> 1296 </dd> 1297 <dt><span><code>--disable-libquadmath</code></span></dt> 1298 <dd><p>Specify that the GCC quad-precision math library should not be built. 1299 On some systems, the library is required to be linkable when building 1300 the Fortran front end, unless <samp>--disable-libquadmath-support</samp> 1301 is used. 1302 </p> 1303 </dd> 1304 <dt><span><code>--disable-libquadmath-support</code></span></dt> 1305 <dd><p>Specify that the Fortran front end and <code>libgfortran</code> do not add 1306 support for <code>libquadmath</code> on systems supporting it. 1307 </p> 1308 </dd> 1309 <dt><span><code>--disable-libgomp</code></span></dt> 1310 <dd><p>Specify that the GNU Offloading and Multi Processing Runtime Library 1311 should not be built. 1312 </p> 1313 </dd> 1314 <dt><span><code>--disable-libvtv</code></span></dt> 1315 <dd><p>Specify that the run-time libraries used by vtable verification 1316 should not be built. 1317 </p> 1318 </dd> 1319 <dt><span><code>--with-dwarf2</code></span></dt> 1320 <dd><p>Specify that the compiler should 1321 use DWARF 2 debugging information as the default. 1322 </p> 1323 </dd> 1324 <dt><span><code>--with-advance-toolchain=<var>at</var></code></span></dt> 1325 <dd><p>On 64-bit PowerPC Linux systems, configure the compiler to use the 1326 header files, library files, and the dynamic linker from the Advance 1327 Toolchain release <var>at</var> instead of the default versions that are 1328 provided by the Linux distribution. In general, this option is 1329 intended for the developers of GCC, and it is not intended for general 1330 use. 1331 </p> 1332 </dd> 1333 <dt><span><code>--enable-targets=all</code></span></dt> 1334 <dt><span><code>--enable-targets=<var>target_list</var></code></span></dt> 1335 <dd><p>Some GCC targets, e.g. powerpc64-linux, build bi-arch compilers. 1336 These are compilers that are able to generate either 64-bit or 32-bit 1337 code. Typically, the corresponding 32-bit target, e.g. 1338 powerpc-linux for powerpc64-linux, only generates 32-bit code. This 1339 option enables the 32-bit target to be a bi-arch compiler, which is 1340 useful when you want a bi-arch compiler that defaults to 32-bit, and 1341 you are building a bi-arch or multi-arch binutils in a combined tree. 1342 On mips-linux, this will build a tri-arch compiler (ABI o32/n32/64), 1343 defaulted to o32. 1344 Currently, this option only affects sparc-linux, powerpc-linux, x86-linux, 1345 mips-linux and s390-linux. 1346 </p> 1347 </dd> 1348 <dt><span><code>--enable-default-pie</code></span></dt> 1349 <dd><p>Turn on <samp>-fPIE</samp> and <samp>-pie</samp> by default. 1350 </p> 1351 </dd> 1352 <dt><span><code>--enable-secureplt</code></span></dt> 1353 <dd><p>This option enables <samp>-msecure-plt</samp> by default for powerpc-linux. 1354 See “RS/6000 and PowerPC Options” in the main manual 1355 </p> 1356 </dd> 1357 <dt><span><code>--enable-default-ssp</code></span></dt> 1358 <dd><p>Turn on <samp>-fstack-protector-strong</samp> by default. 1359 </p> 1360 </dd> 1361 <dt><span><code>--enable-cld</code></span></dt> 1362 <dd><p>This option enables <samp>-mcld</samp> by default for 32-bit x86 targets. 1363 See “i386 and x86-64 Options” in the main manual 1364 </p> 1365 </dd> 1366 <dt><span><code>--enable-large-address-aware</code></span></dt> 1367 <dd><p>The <samp>--enable-large-address-aware</samp> option arranges for MinGW 1368 executables to be linked using the <samp>--large-address-aware</samp> 1369 option, that enables the use of more than 2GB of memory. If GCC is 1370 configured with this option, its effects can be reversed by passing the 1371 <samp>-Wl,--disable-large-address-aware</samp> option to the so-configured 1372 compiler driver. 1373 </p> 1374 </dd> 1375 <dt><span><code>--enable-win32-registry</code></span></dt> 1376 <dt><span><code>--enable-win32-registry=<var>key</var></code></span></dt> 1377 <dt><span><code>--disable-win32-registry</code></span></dt> 1378 <dd><p>The <samp>--enable-win32-registry</samp> option enables Microsoft Windows-hosted GCC 1379 to look up installations paths in the registry using the following key: 1380 </p> 1381 <div class="example"> 1382 <pre class="example"><code>HKEY_LOCAL_MACHINE\SOFTWARE\Free Software Foundation\<var>key</var></code> 1383 </pre></div> 1384 1385 <p><var>key</var> defaults to GCC version number, and can be overridden by the 1386 <samp>--enable-win32-registry=<var>key</var></samp> option. Vendors and distributors 1387 who use custom installers are encouraged to provide a different key, 1388 perhaps one comprised of vendor name and GCC version number, to 1389 avoid conflict with existing installations. This feature is enabled 1390 by default, and can be disabled by <samp>--disable-win32-registry</samp> 1391 option. This option has no effect on the other hosts. 1392 </p> 1393 </dd> 1394 <dt><span><code>--nfp</code></span></dt> 1395 <dd><p>Specify that the machine does not have a floating point unit. This 1396 option only applies to ‘<samp>m68k-sun-sunos<var>n</var></samp>’. On any other 1397 system, <samp>--nfp</samp> has no effect. 1398 </p> 1399 </dd> 1400 <dt><span><code>--enable-werror</code></span></dt> 1401 <dt><span><code>--disable-werror</code></span></dt> 1402 <dt><span><code>--enable-werror=yes</code></span></dt> 1403 <dt><span><code>--enable-werror=no</code></span></dt> 1404 <dd><p>When you specify this option, it controls whether certain files in the 1405 compiler are built with <samp>-Werror</samp> in bootstrap stage2 and later. 1406 If you don’t specify it, <samp>-Werror</samp> is turned on for the main 1407 development trunk. However it defaults to off for release branches and 1408 final releases. The specific files which get <samp>-Werror</samp> are 1409 controlled by the Makefiles. 1410 </p> 1411 </dd> 1412 <dt><span><code>--enable-checking</code></span></dt> 1413 <dt><span><code>--disable-checking</code></span></dt> 1414 <dt><span><code>--enable-checking=<var>list</var></code></span></dt> 1415 <dd><p>This option controls performing internal consistency checks in the compiler. 1416 It does not change the generated code, but adds error checking of the 1417 requested complexity. This slows down the compiler and may only work 1418 properly if you are building the compiler with GCC. 1419 </p> 1420 <p>When the option is not specified, the active set of checks depends on context. 1421 Namely, bootstrap stage 1 defaults to ‘<samp>--enable-checking=yes</samp>’, builds 1422 from release branches or release archives default to 1423 ‘<samp>--enable-checking=release</samp>’, and otherwise 1424 ‘<samp>--enable-checking=yes,extra</samp>’ is used. When the option is 1425 specified without a <var>list</var>, the result is the same as 1426 ‘<samp>--enable-checking=yes</samp>’. Likewise, ‘<samp>--disable-checking</samp>’ is 1427 equivalent to ‘<samp>--enable-checking=no</samp>’. 1428 </p> 1429 <p>The categories of checks available in <var>list</var> are ‘<samp>yes</samp>’ (most common 1430 checks ‘<samp>assert,misc,gc,gimple,rtlflag,runtime,tree,types</samp>’), ‘<samp>no</samp>’ 1431 (no checks at all), ‘<samp>all</samp>’ (all but ‘<samp>valgrind</samp>’), ‘<samp>release</samp>’ 1432 (cheapest checks ‘<samp>assert,runtime</samp>’) or ‘<samp>none</samp>’ (same as ‘<samp>no</samp>’). 1433 ‘<samp>release</samp>’ checks are always on and to disable them 1434 ‘<samp>--disable-checking</samp>’ or ‘<samp>--enable-checking=no[,<other checks>]</samp>’ 1435 must be explicitly requested. Disabling assertions makes the compiler and 1436 runtime slightly faster but increases the risk of undetected internal errors 1437 causing wrong code to be generated. 1438 </p> 1439 <p>Individual checks can be enabled with these flags: ‘<samp>assert</samp>’, ‘<samp>df</samp>’, 1440 ‘<samp>extra</samp>’, ‘<samp>fold</samp>’, ‘<samp>gc</samp>’, ‘<samp>gcac</samp>’, ‘<samp>gimple</samp>’, 1441 ‘<samp>misc</samp>’, ‘<samp>rtl</samp>’, ‘<samp>rtlflag</samp>’, ‘<samp>runtime</samp>’, ‘<samp>tree</samp>’, 1442 ‘<samp>types</samp>’ and ‘<samp>valgrind</samp>’. ‘<samp>extra</samp>’ extends ‘<samp>misc</samp>’ 1443 checking with extra checks that might affect code generation and should 1444 therefore not differ between stage1 and later stages in bootstrap. 1445 </p> 1446 <p>The ‘<samp>valgrind</samp>’ check requires the external <code>valgrind</code> simulator, 1447 available from <a href="http://valgrind.org/">http://valgrind.org/</a>. The ‘<samp>rtl</samp>’ checks are 1448 expensive and the ‘<samp>df</samp>’, ‘<samp>gcac</samp>’ and ‘<samp>valgrind</samp>’ checks are very 1449 expensive. 1450 </p> 1451 </dd> 1452 <dt><span><code>--disable-stage1-checking</code></span></dt> 1453 <dt><span><code>--enable-stage1-checking</code></span></dt> 1454 <dt><span><code>--enable-stage1-checking=<var>list</var></code></span></dt> 1455 <dd><p>This option affects only bootstrap build. If no <samp>--enable-checking</samp> 1456 option is specified the stage1 compiler is built with ‘<samp>yes</samp>’ checking 1457 enabled, otherwise the stage1 checking flags are the same as specified by 1458 <samp>--enable-checking</samp>. To build the stage1 compiler with 1459 different checking options use <samp>--enable-stage1-checking</samp>. 1460 The list of checking options is the same as for <samp>--enable-checking</samp>. 1461 If your system is too slow or too small to bootstrap a released compiler 1462 with checking for stage1 enabled, you can use ‘<samp>--disable-stage1-checking</samp>’ 1463 to disable checking for the stage1 compiler. 1464 </p> 1465 </dd> 1466 <dt><span><code>--enable-coverage</code></span></dt> 1467 <dt><span><code>--enable-coverage=<var>level</var></code></span></dt> 1468 <dd><p>With this option, the compiler is built to collect self coverage 1469 information, every time it is run. This is for internal development 1470 purposes, and only works when the compiler is being built with gcc. The 1471 <var>level</var> argument controls whether the compiler is built optimized or 1472 not, values are ‘<samp>opt</samp>’ and ‘<samp>noopt</samp>’. For coverage analysis you 1473 want to disable optimization, for performance analysis you want to 1474 enable optimization. When coverage is enabled, the default level is 1475 without optimization. 1476 </p> 1477 </dd> 1478 <dt><span><code>--enable-gather-detailed-mem-stats</code></span></dt> 1479 <dd><p>When this option is specified more detailed information on memory 1480 allocation is gathered. This information is printed when using 1481 <samp>-fmem-report</samp>. 1482 </p> 1483 </dd> 1484 <dt><span><code>--enable-valgrind-annotations</code></span></dt> 1485 <dd><p>Mark selected memory related operations in the compiler when run under 1486 valgrind to suppress false positives. 1487 </p> 1488 </dd> 1489 <dt><span><code>--enable-nls</code></span></dt> 1490 <dt><span><code>--disable-nls</code></span></dt> 1491 <dd><p>The <samp>--enable-nls</samp> option enables Native Language Support (NLS), 1492 which lets GCC output diagnostics in languages other than American 1493 English. Native Language Support is enabled by default if not doing a 1494 canadian cross build. The <samp>--disable-nls</samp> option disables NLS. 1495 </p> 1496 </dd> 1497 <dt><span><code>--with-included-gettext</code></span></dt> 1498 <dd><p>If NLS is enabled, the <samp>--with-included-gettext</samp> option causes the build 1499 procedure to prefer its copy of GNU <code>gettext</code>. 1500 </p> 1501 </dd> 1502 <dt><span><code>--with-catgets</code></span></dt> 1503 <dd><p>If NLS is enabled, and if the host lacks <code>gettext</code> but has the 1504 inferior <code>catgets</code> interface, the GCC build procedure normally 1505 ignores <code>catgets</code> and instead uses GCC’s copy of the GNU 1506 <code>gettext</code> library. The <samp>--with-catgets</samp> option causes the 1507 build procedure to use the host’s <code>catgets</code> in this situation. 1508 </p> 1509 </dd> 1510 <dt><span><code>--with-libiconv-prefix=<var>dir</var></code></span></dt> 1511 <dd><p>Search for libiconv header files in <samp><var>dir</var>/include</samp> and 1512 libiconv library files in <samp><var>dir</var>/lib</samp>. 1513 </p> 1514 </dd> 1515 <dt><span><code>--enable-obsolete</code></span></dt> 1516 <dd><p>Enable configuration for an obsoleted system. If you attempt to 1517 configure GCC for a system (build, host, or target) which has been 1518 obsoleted, and you do not specify this flag, configure will halt with an 1519 error message. 1520 </p> 1521 <p>All support for systems which have been obsoleted in one release of GCC 1522 is removed entirely in the next major release, unless someone steps 1523 forward to maintain the port. 1524 </p> 1525 </dd> 1526 <dt><span><code>--enable-decimal-float</code></span></dt> 1527 <dt><span><code>--enable-decimal-float=yes</code></span></dt> 1528 <dt><span><code>--enable-decimal-float=no</code></span></dt> 1529 <dt><span><code>--enable-decimal-float=bid</code></span></dt> 1530 <dt><span><code>--enable-decimal-float=dpd</code></span></dt> 1531 <dt><span><code>--disable-decimal-float</code></span></dt> 1532 <dd><p>Enable (or disable) support for the C decimal floating point extension 1533 that is in the IEEE 754-2008 standard. This is enabled by default only 1534 on PowerPC, i386, and x86_64 GNU/Linux systems. Other systems may also 1535 support it, but require the user to specifically enable it. You can 1536 optionally control which decimal floating point format is used (either 1537 ‘<samp>bid</samp>’ or ‘<samp>dpd</samp>’). The ‘<samp>bid</samp>’ (binary integer decimal) 1538 format is default on i386 and x86_64 systems, and the ‘<samp>dpd</samp>’ 1539 (densely packed decimal) format is default on PowerPC systems. 1540 </p> 1541 </dd> 1542 <dt><span><code>--enable-fixed-point</code></span></dt> 1543 <dt><span><code>--disable-fixed-point</code></span></dt> 1544 <dd><p>Enable (or disable) support for C fixed-point arithmetic. 1545 This option is enabled by default for some targets (such as MIPS) which 1546 have hardware-support for fixed-point operations. On other targets, you 1547 may enable this option manually. 1548 </p> 1549 </dd> 1550 <dt><span><code>--with-long-double-128</code></span></dt> 1551 <dd><p>Specify if <code>long double</code> type should be 128-bit by default on selected 1552 GNU/Linux architectures. If using <code>--without-long-double-128</code>, 1553 <code>long double</code> will be by default 64-bit, the same as <code>double</code> type. 1554 When neither of these configure options are used, the default will be 1555 128-bit <code>long double</code> when built against GNU C Library 2.4 and later, 1556 64-bit <code>long double</code> otherwise. 1557 </p> 1558 </dd> 1559 <dt><span><code>--with-long-double-format=ibm</code></span></dt> 1560 <dt><span><code>--with-long-double-format=ieee</code></span></dt> 1561 <dd><p>Specify whether <code>long double</code> uses the IBM extended double format 1562 or the IEEE 128-bit floating point format on PowerPC Linux systems. 1563 This configuration switch will only work on little endian PowerPC 1564 Linux systems and on big endian 64-bit systems where the default cpu 1565 is at least power7 (i.e. <samp>--with-cpu=power7</samp>, 1566 <samp>--with-cpu=power8</samp>, or <samp>--with-cpu=power9</samp> is used). 1567 </p> 1568 <p>If you use the <samp>--with-long-double-64</samp> configuration option, 1569 the <samp>--with-long-double-format=ibm</samp> and 1570 <samp>--with-long-double-format=ieee</samp> options are ignored. 1571 </p> 1572 <p>The default <code>long double</code> format is to use IBM extended double. 1573 Until all of the libraries are converted to use IEEE 128-bit floating 1574 point, it is not recommended to use 1575 <samp>--with-long-double-format=ieee</samp>. 1576 </p> 1577 <p>On little endian PowerPC Linux systems, if you explicitly set the 1578 <code>long double</code> type, it will build multilibs to allow you to 1579 select either <code>long double</code> format, unless you disable multilibs 1580 with the <code>--disable-multilib</code> option. At present, 1581 <code>long double</code> multilibs are not built on big endian PowerPC Linux 1582 systems. If you are building multilibs, you will need to configure 1583 the compiler using the <samp>--with-system-zlib</samp> option. 1584 </p> 1585 <p>If you do not set the <code>long double</code> type explicitly, no multilibs 1586 will be generated. 1587 </p> 1588 </dd> 1589 <dt><span><code>--enable-fdpic</code></span></dt> 1590 <dd><p>On SH Linux systems, generate ELF FDPIC code. 1591 </p> 1592 </dd> 1593 <dt><span><code>--with-gmp=<var>pathname</var></code></span></dt> 1594 <dt><span><code>--with-gmp-include=<var>pathname</var></code></span></dt> 1595 <dt><span><code>--with-gmp-lib=<var>pathname</var></code></span></dt> 1596 <dt><span><code>--with-mpfr=<var>pathname</var></code></span></dt> 1597 <dt><span><code>--with-mpfr-include=<var>pathname</var></code></span></dt> 1598 <dt><span><code>--with-mpfr-lib=<var>pathname</var></code></span></dt> 1599 <dt><span><code>--with-mpc=<var>pathname</var></code></span></dt> 1600 <dt><span><code>--with-mpc-include=<var>pathname</var></code></span></dt> 1601 <dt><span><code>--with-mpc-lib=<var>pathname</var></code></span></dt> 1602 <dd><p>If you want to build GCC but do not have the GMP library, the MPFR 1603 library and/or the MPC library installed in a standard location and 1604 do not have their sources present in the GCC source tree then you 1605 can explicitly specify the directory where they are installed 1606 (‘<samp>--with-gmp=<var>gmpinstalldir</var></samp>’, 1607 ‘<samp>--with-mpfr=<var>mpfrinstalldir</var></samp>’, 1608 ‘<samp>--with-mpc=<var>mpcinstalldir</var></samp>’). The 1609 <samp>--with-gmp=<var>gmpinstalldir</var></samp> option is shorthand for 1610 <samp>--with-gmp-lib=<var>gmpinstalldir</var>/lib</samp> and 1611 <samp>--with-gmp-include=<var>gmpinstalldir</var>/include</samp>. Likewise the 1612 <samp>--with-mpfr=<var>mpfrinstalldir</var></samp> option is shorthand for 1613 <samp>--with-mpfr-lib=<var>mpfrinstalldir</var>/lib</samp> and 1614 <samp>--with-mpfr-include=<var>mpfrinstalldir</var>/include</samp>, also the 1615 <samp>--with-mpc=<var>mpcinstalldir</var></samp> option is shorthand for 1616 <samp>--with-mpc-lib=<var>mpcinstalldir</var>/lib</samp> and 1617 <samp>--with-mpc-include=<var>mpcinstalldir</var>/include</samp>. If these 1618 shorthand assumptions are not correct, you can use the explicit 1619 include and lib options directly. You might also need to ensure the 1620 shared libraries can be found by the dynamic linker when building and 1621 using GCC, for example by setting the runtime shared library path 1622 variable (<code>LD_LIBRARY_PATH</code> on GNU/Linux and Solaris systems). 1623 </p> 1624 <p>These flags are applicable to the host platform only. When building 1625 a cross compiler, they will not be used to configure target libraries. 1626 </p> 1627 </dd> 1628 <dt><span><code>--with-isl=<var>pathname</var></code></span></dt> 1629 <dt><span><code>--with-isl-include=<var>pathname</var></code></span></dt> 1630 <dt><span><code>--with-isl-lib=<var>pathname</var></code></span></dt> 1631 <dd><p>If you do not have the isl library installed in a standard location and you 1632 want to build GCC, you can explicitly specify the directory where it is 1633 installed (‘<samp>--with-isl=<var>islinstalldir</var></samp>’). The 1634 <samp>--with-isl=<var>islinstalldir</var></samp> option is shorthand for 1635 <samp>--with-isl-lib=<var>islinstalldir</var>/lib</samp> and 1636 <samp>--with-isl-include=<var>islinstalldir</var>/include</samp>. If this 1637 shorthand assumption is not correct, you can use the explicit 1638 include and lib options directly. 1639 </p> 1640 <p>These flags are applicable to the host platform only. When building 1641 a cross compiler, they will not be used to configure target libraries. 1642 </p> 1643 </dd> 1644 <dt><span><code>--with-stage1-ldflags=<var>flags</var></code></span></dt> 1645 <dd><p>This option may be used to set linker flags to be used when linking 1646 stage 1 of GCC. These are also used when linking GCC if configured with 1647 <samp>--disable-bootstrap</samp>. If <samp>--with-stage1-libs</samp> is not set to a 1648 value, then the default is ‘<samp>-static-libstdc++ -static-libgcc</samp>’, if 1649 supported. 1650 </p> 1651 </dd> 1652 <dt><span><code>--with-stage1-libs=<var>libs</var></code></span></dt> 1653 <dd><p>This option may be used to set libraries to be used when linking stage 1 1654 of GCC. These are also used when linking GCC if configured with 1655 <samp>--disable-bootstrap</samp>. 1656 </p> 1657 </dd> 1658 <dt><span><code>--with-boot-ldflags=<var>flags</var></code></span></dt> 1659 <dd><p>This option may be used to set linker flags to be used when linking 1660 stage 2 and later when bootstrapping GCC. If –with-boot-libs 1661 is not is set to a value, then the default is 1662 ‘<samp>-static-libstdc++ -static-libgcc</samp>’. 1663 </p> 1664 </dd> 1665 <dt><span><code>--with-boot-libs=<var>libs</var></code></span></dt> 1666 <dd><p>This option may be used to set libraries to be used when linking stage 2 1667 and later when bootstrapping GCC. 1668 </p> 1669 </dd> 1670 <dt><span><code>--with-debug-prefix-map=<var>map</var></code></span></dt> 1671 <dd><p>Convert source directory names using <samp>-fdebug-prefix-map</samp> when 1672 building runtime libraries. ‘<samp><var>map</var></samp>’ is a space-separated 1673 list of maps of the form ‘<samp><var>old</var>=<var>new</var></samp>’. 1674 </p> 1675 </dd> 1676 <dt><span><code>--enable-linker-build-id</code></span></dt> 1677 <dd><p>Tells GCC to pass <samp>--build-id</samp> option to the linker for all final 1678 links (links performed without the <samp>-r</samp> or <samp>--relocatable</samp> 1679 option), if the linker supports it. If you specify 1680 <samp>--enable-linker-build-id</samp>, but your linker does not 1681 support <samp>--build-id</samp> option, a warning is issued and the 1682 <samp>--enable-linker-build-id</samp> option is ignored. The default is off. 1683 </p> 1684 </dd> 1685 <dt><span><code>--with-linker-hash-style=<var>choice</var></code></span></dt> 1686 <dd><p>Tells GCC to pass <samp>--hash-style=<var>choice</var></samp> option to the 1687 linker for all final links. <var>choice</var> can be one of 1688 ‘<samp>sysv</samp>’, ‘<samp>gnu</samp>’, and ‘<samp>both</samp>’ where ‘<samp>sysv</samp>’ is the default. 1689 </p> 1690 </dd> 1691 <dt><span><code>--enable-gnu-unique-object</code></span></dt> 1692 <dt><span><code>--disable-gnu-unique-object</code></span></dt> 1693 <dd><p>Tells GCC to use the gnu_unique_object relocation for C++ template 1694 static data members and inline function local statics. Enabled by 1695 default for a toolchain with an assembler that accepts it and 1696 GLIBC 2.11 or above, otherwise disabled. 1697 </p> 1698 </dd> 1699 <dt><span><code>--with-diagnostics-color=<var>choice</var></code></span></dt> 1700 <dd><p>Tells GCC to use <var>choice</var> as the default for <samp>-fdiagnostics-color=</samp> 1701 option (if not used explicitly on the command line). <var>choice</var> 1702 can be one of ‘<samp>never</samp>’, ‘<samp>auto</samp>’, ‘<samp>always</samp>’, and ‘<samp>auto-if-env</samp>’ 1703 where ‘<samp>auto</samp>’ is the default. ‘<samp>auto-if-env</samp>’ makes 1704 <samp>-fdiagnostics-color=auto</samp> the default if <code>GCC_COLORS</code> 1705 is present and non-empty in the environment of the compiler, and 1706 <samp>-fdiagnostics-color=never</samp> otherwise. 1707 </p> 1708 </dd> 1709 <dt><span><code>--with-diagnostics-urls=<var>choice</var></code></span></dt> 1710 <dd><p>Tells GCC to use <var>choice</var> as the default for <samp>-fdiagnostics-urls=</samp> 1711 option (if not used explicitly on the command line). <var>choice</var> 1712 can be one of ‘<samp>never</samp>’, ‘<samp>auto</samp>’, ‘<samp>always</samp>’, and ‘<samp>auto-if-env</samp>’ 1713 where ‘<samp>auto</samp>’ is the default. ‘<samp>auto-if-env</samp>’ makes 1714 <samp>-fdiagnostics-urls=auto</samp> the default if <code>GCC_URLS</code> 1715 or <code>TERM_URLS</code> is present and non-empty in the environment of the 1716 compiler, and <samp>-fdiagnostics-urls=never</samp> otherwise. 1717 </p> 1718 </dd> 1719 <dt><span><code>--enable-lto</code></span></dt> 1720 <dt><span><code>--disable-lto</code></span></dt> 1721 <dd><p>Enable support for link-time optimization (LTO). This is enabled by 1722 default, and may be disabled using <samp>--disable-lto</samp>. 1723 </p> 1724 </dd> 1725 <dt><span><code>--enable-linker-plugin-configure-flags=FLAGS</code></span></dt> 1726 <dt><span><code>--enable-linker-plugin-flags=FLAGS</code></span></dt> 1727 <dd><p>By default, linker plugins (such as the LTO plugin) are built for the 1728 host system architecture. For the case that the linker has a 1729 different (but run-time compatible) architecture, these flags can be 1730 specified to build plugins that are compatible to the linker. For 1731 example, if you are building GCC for a 64-bit x86_64 1732 (‘<samp>x86_64-pc-linux-gnu</samp>’) host system, but have a 32-bit x86 1733 GNU/Linux (‘<samp>i686-pc-linux-gnu</samp>’) linker executable (which is 1734 executable on the former system), you can configure GCC as follows for 1735 getting compatible linker plugins: 1736 </p> 1737 <div class="example"> 1738 <pre class="example">% <var>srcdir</var>/configure \ 1739 --host=x86_64-pc-linux-gnu \ 1740 --enable-linker-plugin-configure-flags=--host=i686-pc-linux-gnu \ 1741 --enable-linker-plugin-flags='CC=gcc\ -m32\ -Wl,-rpath,[...]/i686-pc-linux-gnu/lib' 1742 </pre></div> 1743 1744 </dd> 1745 <dt><span><code>--with-plugin-ld=<var>pathname</var></code></span></dt> 1746 <dd><p>Enable an alternate linker to be used at link-time optimization (LTO) 1747 link time when <samp>-fuse-linker-plugin</samp> is enabled. 1748 This linker should have plugin support such as gold starting with 1749 version 2.20 or GNU ld starting with version 2.21. 1750 See <samp>-fuse-linker-plugin</samp> for details. 1751 </p> 1752 </dd> 1753 <dt><span><code>--enable-canonical-system-headers</code></span></dt> 1754 <dt><span><code>--disable-canonical-system-headers</code></span></dt> 1755 <dd><p>Enable system header path canonicalization for <samp>libcpp</samp>. This can 1756 produce shorter header file paths in diagnostics and dependency output 1757 files, but these changed header paths may conflict with some compilation 1758 environments. Enabled by default, and may be disabled using 1759 <samp>--disable-canonical-system-headers</samp>. 1760 </p> 1761 </dd> 1762 <dt><span><code>--with-glibc-version=<var>major</var>.<var>minor</var></code></span></dt> 1763 <dd><p>Tell GCC that when the GNU C Library (glibc) is used on the target it 1764 will be version <var>major</var>.<var>minor</var> or later. Normally this can 1765 be detected from the C library’s header files, but this option may be 1766 needed when bootstrapping a cross toolchain without the header files 1767 available for building the initial bootstrap compiler. 1768 </p> 1769 <p>If GCC is configured with some multilibs that use glibc and some that 1770 do not, this option applies only to the multilibs that use glibc. 1771 However, such configurations may not work well as not all the relevant 1772 configuration in GCC is on a per-multilib basis. 1773 </p> 1774 </dd> 1775 <dt><span><code>--enable-as-accelerator-for=<var>target</var></code></span></dt> 1776 <dd><p>Build as offload target compiler. Specify offload host triple by <var>target</var>. 1777 </p> 1778 </dd> 1779 <dt><span><code>--enable-offload-targets=<var>target1</var>[=<var>path1</var>],…,<var>targetN</var>[=<var>pathN</var>]</code></span></dt> 1780 <dd><p>Enable offloading to targets <var>target1</var>, …, <var>targetN</var>. 1781 Offload compilers are expected to be already installed. Default search 1782 path for them is <samp><var>exec-prefix</var></samp>, but it can be changed by 1783 specifying paths <var>path1</var>, …, <var>pathN</var>. 1784 </p> 1785 <div class="example"> 1786 <pre class="example">% <var>srcdir</var>/configure \ 1787 --enable-offload-targets=x86_64-intelmicemul-linux-gnu=/path/to/x86_64/compiler,nvptx-none,hsa 1788 </pre></div> 1789 1790 <p>If ‘<samp>hsa</samp>’ is specified as one of the targets, the compiler will be 1791 built with support for HSA GPU accelerators. Because the same 1792 compiler will emit the accelerator code, no path should be specified. 1793 </p> 1794 </dd> 1795 <dt><span><code>--with-hsa-runtime=<var>pathname</var></code></span></dt> 1796 <dt><span><code>--with-hsa-runtime-include=<var>pathname</var></code></span></dt> 1797 <dt><span><code>--with-hsa-runtime-lib=<var>pathname</var></code></span></dt> 1798 <dd> 1799 <p>If you configure GCC with HSA offloading but do not have the HSA 1800 run-time library installed in a standard location then you can 1801 explicitly specify the directory where they are installed. The 1802 <samp>--with-hsa-runtime=<var>hsainstalldir</var></samp> option is a 1803 shorthand for 1804 <samp>--with-hsa-runtime-lib=<var>hsainstalldir</var>/lib</samp> and 1805 <samp>--with-hsa-runtime-include=<var>hsainstalldir</var>/include</samp>. 1806 </p> 1807 </dd> 1808 <dt><span><code>--enable-cet</code></span></dt> 1809 <dt><span><code>--disable-cet</code></span></dt> 1810 <dd><p>Enable building target run-time libraries with control-flow 1811 instrumentation, see <samp>-fcf-protection</samp> option. When 1812 <code>--enable-cet</code> is specified target libraries are configured 1813 to add <samp>-fcf-protection</samp> and, if needed, other target 1814 specific options to a set of building options. 1815 </p> 1816 <p>The option is disabled by default. When <code>--enable-cet=auto</code> 1817 is used, it is enabled on Linux/x86 if target binutils 1818 supports <code>Intel CET</code> instructions and disabled otherwise. 1819 In this case the target libraries are configured to get additional 1820 <samp>-fcf-protection</samp> option. 1821 </p> 1822 </dd> 1823 <dt><span><code>--with-riscv-attribute=‘<samp>yes</samp>’, ‘<samp>no</samp>’ or ‘<samp>default</samp>’</code></span></dt> 1824 <dd><p>Generate RISC-V attribute by default, in order to record extra build 1825 information in object. 1826 </p> 1827 <p>The option is disabled by default. It is enabled on RISC-V/ELF (bare-metal) 1828 target if target binutils supported. 1829 </p></dd> 1830 </dl> 1831 1832 <span id="Cross-Compiler-Specific-Options"></span><h4 class="subheading">Cross-Compiler-Specific Options</h4> 1833 <p>The following options only apply to building cross compilers. 1834 </p> 1835 <dl compact="compact"> 1836 <dt><span><code>--with-toolexeclibdir=<var>dir</var></code></span></dt> 1837 <dd><p>Specify the installation directory for libraries built with a cross compiler. 1838 The default is <samp>${gcc_tooldir}/lib</samp>. 1839 </p> 1840 </dd> 1841 <dt><span><code>--with-sysroot</code></span></dt> 1842 <dt><span><code>--with-sysroot=<var>dir</var></code></span></dt> 1843 <dd><p>Tells GCC to consider <var>dir</var> as the root of a tree that contains 1844 (a subset of) the root filesystem of the target operating system. 1845 Target system headers, libraries and run-time object files will be 1846 searched for in there. More specifically, this acts as if 1847 <samp>--sysroot=<var>dir</var></samp> was added to the default options of the built 1848 compiler. The specified directory is not copied into the 1849 install tree, unlike the options <samp>--with-headers</samp> and 1850 <samp>--with-libs</samp> that this option obsoletes. The default value, 1851 in case <samp>--with-sysroot</samp> is not given an argument, is 1852 <samp>${gcc_tooldir}/sys-root</samp>. If the specified directory is a 1853 subdirectory of <samp>${exec_prefix}</samp>, then it will be found relative to 1854 the GCC binaries if the installation tree is moved. 1855 </p> 1856 <p>This option affects the system root for the compiler used to build 1857 target libraries (which runs on the build system) and the compiler newly 1858 installed with <code>make install</code>; it does not affect the compiler which is 1859 used to build GCC itself. 1860 </p> 1861 <p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp> 1862 option then the compiler will search that directory within <var>dirname</var> for 1863 native system headers rather than the default <samp>/usr/include</samp>. 1864 </p> 1865 </dd> 1866 <dt><span><code>--with-build-sysroot</code></span></dt> 1867 <dt><span><code>--with-build-sysroot=<var>dir</var></code></span></dt> 1868 <dd><p>Tells GCC to consider <var>dir</var> as the system root (see 1869 <samp>--with-sysroot</samp>) while building target libraries, instead of 1870 the directory specified with <samp>--with-sysroot</samp>. This option is 1871 only useful when you are already using <samp>--with-sysroot</samp>. You 1872 can use <samp>--with-build-sysroot</samp> when you are configuring with 1873 <samp>--prefix</samp> set to a directory that is different from the one in 1874 which you are installing GCC and your target libraries. 1875 </p> 1876 <p>This option affects the system root for the compiler used to build 1877 target libraries (which runs on the build system); it does not affect 1878 the compiler which is used to build GCC itself. 1879 </p> 1880 <p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp> 1881 option then the compiler will search that directory within <var>dirname</var> for 1882 native system headers rather than the default <samp>/usr/include</samp>. 1883 </p> 1884 </dd> 1885 <dt><span><code>--with-headers</code></span></dt> 1886 <dt><span><code>--with-headers=<var>dir</var></code></span></dt> 1887 <dd><p>Deprecated in favor of <samp>--with-sysroot</samp>. 1888 Specifies that target headers are available when building a cross compiler. 1889 The <var>dir</var> argument specifies a directory which has the target include 1890 files. These include files will be copied into the <samp>gcc</samp> install 1891 directory. <em>This option with the <var>dir</var> argument is required</em> when 1892 building a cross compiler, if <samp><var>prefix</var>/<var>target</var>/sys-include</samp> 1893 doesn’t pre-exist. If <samp><var>prefix</var>/<var>target</var>/sys-include</samp> does 1894 pre-exist, the <var>dir</var> argument may be omitted. <code>fixincludes</code> 1895 will be run on these files to make them compatible with GCC. 1896 </p> 1897 </dd> 1898 <dt><span><code>--without-headers</code></span></dt> 1899 <dd><p>Tells GCC not use any target headers from a libc when building a cross 1900 compiler. When crossing to GNU/Linux, you need the headers so GCC 1901 can build the exception handling for libgcc. 1902 </p> 1903 </dd> 1904 <dt><span><code>--with-libs</code></span></dt> 1905 <dt><span><code>--with-libs="<var>dir1</var> <var>dir2</var> … <var>dirN</var>"</code></span></dt> 1906 <dd><p>Deprecated in favor of <samp>--with-sysroot</samp>. 1907 Specifies a list of directories which contain the target runtime 1908 libraries. These libraries will be copied into the <samp>gcc</samp> install 1909 directory. If the directory list is omitted, this option has no 1910 effect. 1911 </p> 1912 </dd> 1913 <dt><span><code>--with-newlib</code></span></dt> 1914 <dd><p>Specifies that ‘<samp>newlib</samp>’ is 1915 being used as the target C library. This causes <code>__eprintf</code> to be 1916 omitted from <samp>libgcc.a</samp> on the assumption that it will be provided by 1917 ‘<samp>newlib</samp>’. 1918 </p> 1919 <a name="avr"></a> 1920 </dd> 1921 <dt><span><code>--with-avrlibc</code></span></dt> 1922 <dd><p>Only supported for the AVR target. Specifies that ‘<samp>AVR-Libc</samp>’ is 1923 being used as the target C library. This causes float support 1924 functions like <code>__addsf3</code> to be omitted from <samp>libgcc.a</samp> on 1925 the assumption that it will be provided by <samp>libm.a</samp>. For more 1926 technical details, cf. <a href="http://gcc.gnu.org/PR54461">PR54461</a>. 1927 It is not supported for 1928 RTEMS configurations, which currently use newlib. The option is 1929 supported since version 4.7.2 and is the default in 4.8.0 and newer. 1930 </p> 1931 </dd> 1932 <dt><span><code>--with-double={32|64|32,64|64,32}</code></span></dt> 1933 <dt><span><code>--with-long-double={32|64|32,64|64,32|double}</code></span></dt> 1934 <dd><p>Only supported for the AVR target since version 10. 1935 Specify the default layout available for the C/C++ ‘<samp>double</samp>’ 1936 and ‘<samp>long double</samp>’ type, respectively. The following rules apply: 1937 </p><ul> 1938 <li> The first value after the ‘<samp>=</samp>’ specifies the default layout (in bits) 1939 of the type and also the default for the <samp>-mdouble=</samp> resp. 1940 <samp>-mlong-double=</samp> compiler option. 1941 </li><li> If more than one value is specified, respective multilib variants are 1942 available, and <samp>-mdouble=</samp> resp. <samp>-mlong-double=</samp> acts 1943 as a multilib option. 1944 </li><li> If <samp>--with-long-double=double</samp> is specified, ‘<samp>double</samp>’ and 1945 ‘<samp>long double</samp>’ will have the same layout. 1946 </li><li> The defaults are <samp>--with-long-double=64,32</samp> and 1947 <samp>--with-double=32,64</samp>. The default ‘<samp>double</samp>’ layout imposed by 1948 the latter is compatible with older versions of the compiler that implement 1949 ‘<samp>double</samp>’ as a 32-bit type, which does not comply to the language standard. 1950 </li></ul> 1951 <p>Not all combinations of <samp>--with-double=</samp> and 1952 <samp>--with-long-double=</samp> are valid. For example, the combination 1953 <samp>--with-double=32,64</samp> <samp>--with-long-double=32</samp> will be 1954 rejected because the first option specifies the availability of 1955 multilibs for ‘<samp>double</samp>’, whereas the second option implies 1956 that ‘<samp>long double</samp>’ — and hence also ‘<samp>double</samp>’ — is always 1957 32 bits wide. 1958 </p> 1959 </dd> 1960 <dt><span><code>--with-double-comparison={tristate|bool|libf7}</code></span></dt> 1961 <dd><p>Only supported for the AVR target since version 10. 1962 Specify what result format is returned by library functions that 1963 compare 64-bit floating point values (<code>DFmode</code>). 1964 The GCC default is ‘<samp>tristate</samp>’. If the floating point 1965 implementation returns a boolean instead, set it to ‘<samp>bool</samp>’. 1966 </p> 1967 </dd> 1968 <dt><span><code>--with-libf7={libgcc|math|math-symbols|no}</code></span></dt> 1969 <dd><p>Only supported for the AVR target since version 10. 1970 Specify to which degree code from LibF7 is included in libgcc. 1971 LibF7 is an ad-hoc, AVR-specific, 64-bit floating point emulation 1972 written in C and (inline) assembly. ‘<samp>libgcc</samp>’ adds support 1973 for functions that one would usually expect in libgcc like double addition, 1974 double comparisons and double conversions. ‘<samp>math</samp>’ also adds routines 1975 that one would expect in <samp>libm.a</samp>, but with <code>__</code> (two underscores) 1976 prepended to the symbol names as specified by <samp>math.h</samp>. 1977 ‘<samp>math-symbols</samp>’ also defines weak aliases for the functions 1978 declared in <samp>math.h</samp>. However, <code>--with-libf7</code> won’t 1979 install no <samp>math.h</samp> header file whatsoever, this file must come 1980 from elsewhere. This option sets <samp>--with-double-comparison</samp> 1981 to ‘<samp>bool</samp>’. 1982 </p> 1983 </dd> 1984 <dt><span><code>--with-nds32-lib=<var>library</var></code></span></dt> 1985 <dd><p>Specifies that <var>library</var> setting is used for building <samp>libgcc.a</samp>. 1986 Currently, the valid <var>library</var> is ‘<samp>newlib</samp>’ or ‘<samp>mculib</samp>’. 1987 This option is only supported for the NDS32 target. 1988 </p> 1989 </dd> 1990 <dt><span><code>--with-build-time-tools=<var>dir</var></code></span></dt> 1991 <dd><p>Specifies where to find the set of target tools (assembler, linker, etc.) 1992 that will be used while building GCC itself. This option can be useful 1993 if the directory layouts are different between the system you are building 1994 GCC on, and the system where you will deploy it. 1995 </p> 1996 <p>For example, on an ‘<samp>ia64-hp-hpux</samp>’ system, you may have the GNU 1997 assembler and linker in <samp>/usr/bin</samp>, and the native tools in a 1998 different path, and build a toolchain that expects to find the 1999 native tools in <samp>/usr/bin</samp>. 2000 </p> 2001 <p>When you use this option, you should ensure that <var>dir</var> includes 2002 <code>ar</code>, <code>as</code>, <code>ld</code>, <code>nm</code>, 2003 <code>ranlib</code> and <code>strip</code> if necessary, and possibly 2004 <code>objdump</code>. Otherwise, GCC may use an inconsistent set of 2005 tools. 2006 </p></dd> 2007 </dl> 2008 2009 <span id="Overriding-configure-test-results"></span><h4 class="subsubheading">Overriding <code>configure</code> test results</h4> 2010 2011 <p>Sometimes, it might be necessary to override the result of some 2012 <code>configure</code> test, for example in order to ease porting to a new 2013 system or work around a bug in a test. The toplevel <code>configure</code> 2014 script provides three variables for this: 2015 </p> 2016 <dl compact="compact"> 2017 <dt id='index-build_005fconfigargs'><span><code>build_configargs</code><a href='#index-build_005fconfigargs' class='copiable-anchor'> ¶</a></span></dt> 2018 <dd><p>The contents of this variable is passed to all build <code>configure</code> 2019 scripts. 2020 </p> 2021 </dd> 2022 <dt id='index-host_005fconfigargs'><span><code>host_configargs</code><a href='#index-host_005fconfigargs' class='copiable-anchor'> ¶</a></span></dt> 2023 <dd><p>The contents of this variable is passed to all host <code>configure</code> 2024 scripts. 2025 </p> 2026 </dd> 2027 <dt id='index-target_005fconfigargs'><span><code>target_configargs</code><a href='#index-target_005fconfigargs' class='copiable-anchor'> ¶</a></span></dt> 2028 <dd><p>The contents of this variable is passed to all target <code>configure</code> 2029 scripts. 2030 </p> 2031 </dd> 2032 </dl> 2033 2034 <p>In order to avoid shell and <code>make</code> quoting issues for complex 2035 overrides, you can pass a setting for <code>CONFIG_SITE</code> and set 2036 variables in the site file. 2037 </p> 2038 <span id="Objective-C-Specific-Options"></span><h4 class="subheading">Objective-C-Specific Options</h4> 2039 2040 <p>The following options apply to the build of the Objective-C runtime library. 2041 </p> 2042 <dl compact="compact"> 2043 <dt><span><code>--enable-objc-gc</code></span></dt> 2044 <dd><p>Specify that an additional variant of the GNU Objective-C runtime library 2045 is built, using an external build of the Boehm-Demers-Weiser garbage 2046 collector (<a href="https://www.hboehm.info/gc/">https://www.hboehm.info/gc/</a>). This library needs to be 2047 available for each multilib variant, unless configured with 2048 <samp>--enable-objc-gc=‘<samp>auto</samp>’</samp> in which case the build of the 2049 additional runtime library is skipped when not available and the build 2050 continues. 2051 </p> 2052 </dd> 2053 <dt><span><code>--with-target-bdw-gc=<var>list</var></code></span></dt> 2054 <dt><span><code>--with-target-bdw-gc-include=<var>list</var></code></span></dt> 2055 <dt><span><code>--with-target-bdw-gc-lib=<var>list</var></code></span></dt> 2056 <dd><p>Specify search directories for the garbage collector header files and 2057 libraries. <var>list</var> is a comma separated list of key value pairs of the 2058 form ‘<samp><var>multilibdir</var>=<var>path</var></samp>’, where the default multilib key 2059 is named as ‘<samp>.</samp>’ (dot), or is omitted (e.g. 2060 ‘<samp>--with-target-bdw-gc=/opt/bdw-gc,32=/opt-bdw-gc32</samp>’). 2061 </p> 2062 <p>The options <samp>--with-target-bdw-gc-include</samp> and 2063 <samp>--with-target-bdw-gc-lib</samp> must always be specified together 2064 for each multilib variant and they take precedence over 2065 <samp>--with-target-bdw-gc</samp>. If <samp>--with-target-bdw-gc-include</samp> 2066 is missing values for a multilib, then the value for the default 2067 multilib is used (e.g. ‘<samp>--with-target-bdw-gc-include=/opt/bdw-gc/include</samp>’ 2068 ‘<samp>--with-target-bdw-gc-lib=/opt/bdw-gc/lib64,32=/opt-bdw-gc/lib32</samp>’). 2069 If none of these options are specified, the library is assumed in 2070 default locations. 2071 </p></dd> 2072 </dl> 2073 2074 <span id="D-Specific-Options"></span><h4 class="subheading">D-Specific Options</h4> 2075 2076 <p>The following options apply to the build of the D runtime library. 2077 </p> 2078 <dl compact="compact"> 2079 <dt><span><code>--enable-libphobos-checking</code></span></dt> 2080 <dt><span><code>--disable-libphobos-checking</code></span></dt> 2081 <dt><span><code>--enable-libphobos-checking=<var>list</var></code></span></dt> 2082 <dd><p>This option controls whether run-time checks and contracts are compiled into 2083 the D runtime library. When the option is not specified, the library is built 2084 with ‘<samp>release</samp>’ checking. When the option is specified without a 2085 <var>list</var>, the result is the same as ‘<samp>--enable-libphobos-checking=yes</samp>’. 2086 Likewise, ‘<samp>--disable-libphobos-checking</samp>’ is equivalent to 2087 ‘<samp>--enable-libphobos-checking=no</samp>’. 2088 </p> 2089 <p>The categories of checks available in <var>list</var> are ‘<samp>yes</samp>’ (compiles 2090 libphobos with <samp>-fno-release</samp>), ‘<samp>no</samp>’ (compiles libphobos with 2091 <samp>-frelease</samp>), ‘<samp>all</samp>’ (same as ‘<samp>yes</samp>’), ‘<samp>none</samp>’ or 2092 ‘<samp>release</samp>’ (same as ‘<samp>no</samp>’). 2093 </p> 2094 <p>Individual checks available in <var>list</var> are ‘<samp>assert</samp>’ (compiles libphobos 2095 with an extra option <samp>-fassert</samp>). 2096 </p> 2097 </dd> 2098 <dt><span><code>--with-libphobos-druntime-only</code></span></dt> 2099 <dt><span><code>--with-libphobos-druntime-only=<var>choice</var></code></span></dt> 2100 <dd><p>Specify whether to build only the core D runtime library (druntime), or both 2101 the core and standard library (phobos) into libphobos. This is useful for 2102 targets that have full support in druntime, but no or incomplete support 2103 in phobos. <var>choice</var> can be one of ‘<samp>auto</samp>’, ‘<samp>yes</samp>’, and ‘<samp>no</samp>’ 2104 where ‘<samp>auto</samp>’ is the default. 2105 </p> 2106 <p>When the option is not specified, the default choice ‘<samp>auto</samp>’ means that it 2107 is inferred whether the target has support for the phobos standard library. 2108 When the option is specified without a <var>choice</var>, the result is the same as 2109 ‘<samp>--with-libphobos-druntime-only=yes</samp>’. 2110 </p> 2111 </dd> 2112 <dt><span><code>--with-target-system-zlib</code></span></dt> 2113 <dd><p>Use installed ‘<samp>zlib</samp>’ rather than that included with GCC. This needs 2114 to be available for each multilib variant, unless configured with 2115 <samp>--with-target-system-zlib=‘<samp>auto</samp>’</samp> in which case the GCC included 2116 ‘<samp>zlib</samp>’ is only used when the system installed library is not available. 2117 </p></dd> 2118 </dl> 2119 2120 <hr /> 2121 <p> 2122 <p><a href="./index.html">Return to the GCC Installation page</a> 2123 </p> 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 </body> 2136 </html> 2137
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