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Copies published by the Free Software Foundation raise 21 funds for GNU development. --> 22 <!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ --> 23 <head> 24 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 25 <title>Installing GCC</title> 26 27 <meta name="description" content="Installing GCC"> 28 <meta name="keywords" content="Installing GCC"> 29 <meta name="resource-type" content="document"> 30 <meta name="distribution" content="global"> 31 <meta name="Generator" content="makeinfo"> 32 <style type="text/css"> 33 <!-- 34 a.summary-letter {text-decoration: none} 35 blockquote.indentedblock {margin-right: 0em} 36 blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} 37 blockquote.smallquotation {font-size: smaller} 38 div.display {margin-left: 3.2em} 39 div.example {margin-left: 3.2em} 40 div.lisp {margin-left: 3.2em} 41 div.smalldisplay {margin-left: 3.2em} 42 div.smallexample {margin-left: 3.2em} 43 div.smalllisp {margin-left: 3.2em} 44 kbd {font-style: oblique} 45 pre.display {font-family: inherit} 46 pre.format {font-family: inherit} 47 pre.menu-comment {font-family: serif} 48 pre.menu-preformatted {font-family: serif} 49 pre.smalldisplay {font-family: inherit; font-size: smaller} 50 pre.smallexample {font-size: smaller} 51 pre.smallformat {font-family: inherit; font-size: smaller} 52 pre.smalllisp {font-size: smaller} 53 span.nolinebreak {white-space: nowrap} 54 span.roman {font-family: initial; font-weight: normal} 55 span.sansserif {font-family: sans-serif; font-weight: normal} 56 ul.no-bullet {list-style: none} 57 --> 58 </style> 59 60 61 </head> 62 63 <body lang="en"> 64 <h1 class="settitle" align="center">Installing GCC</h1> 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 <a name="index-Configuration"></a> 85 <a name="index-Installing-GCC_003a-Configuration"></a> 86 87 <p>Like most GNU software, GCC must be configured before it can be built. 88 This document describes the recommended configuration procedure 89 for both native and cross targets. 90 </p> 91 <p>We use <var>srcdir</var> to refer to the toplevel source directory for 92 GCC; we use <var>objdir</var> to refer to the toplevel build/object directory. 93 </p> 94 <p>If you obtained the sources by cloning the repository, <var>srcdir</var> 95 must refer to the top <samp>gcc</samp> directory, the one where the 96 <samp>MAINTAINERS</samp> file can be found, and not its <samp>gcc</samp> 97 subdirectory, otherwise the build will fail. 98 </p> 99 <p>If either <var>srcdir</var> or <var>objdir</var> is located on an automounted NFS 100 file system, the shell’s built-in <code>pwd</code> command will return 101 temporary pathnames. Using these can lead to various sorts of build 102 problems. To avoid this issue, set the <code>PWDCMD</code> environment 103 variable to an automounter-aware <code>pwd</code> command, e.g., 104 <code>pawd</code> or ‘<samp>amq -w</samp>’, during the configuration and build 105 phases. 106 </p> 107 <p>First, we <strong>highly</strong> recommend that GCC be built into a 108 separate directory from the sources which does <strong>not</strong> reside 109 within the source tree. This is how we generally build GCC; building 110 where <var>srcdir</var> == <var>objdir</var> should still work, but doesn’t 111 get extensive testing; building where <var>objdir</var> is a subdirectory 112 of <var>srcdir</var> is unsupported. 113 </p> 114 <p>If you have previously built GCC in the same directory for a 115 different target machine, do ‘<samp>make distclean</samp>’ to delete all files 116 that might be invalid. One of the files this deletes is <samp>Makefile</samp>; 117 if ‘<samp>make distclean</samp>’ complains that <samp>Makefile</samp> does not exist 118 or issues a message like “don’t know how to make distclean” it probably 119 means that the directory is already suitably clean. However, with the 120 recommended method of building in a separate <var>objdir</var>, you should 121 simply use a different <var>objdir</var> for each target. 122 </p> 123 <p>Second, when configuring a native system, either <code>cc</code> or 124 <code>gcc</code> must be in your path or you must set <code>CC</code> in 125 your environment before running configure. Otherwise the configuration 126 scripts may fail. 127 </p> 128 129 <p>To configure GCC: 130 </p> 131 <div class="smallexample"> 132 <pre class="smallexample">% mkdir <var>objdir</var> 133 % cd <var>objdir</var> 134 % <var>srcdir</var>/configure [<var>options</var>] [<var>target</var>] 135 </pre></div> 136 137 <a name="Distributor-options"></a> 138 <h3 class="heading">Distributor options</h3> 139 140 <p>If you will be distributing binary versions of GCC, with modifications 141 to the source code, you should use the options described in this 142 section to make clear that your version contains modifications. 143 </p> 144 <dl compact="compact"> 145 <dt><code>--with-pkgversion=<var>version</var></code></dt> 146 <dd><p>Specify a string that identifies your package. You may wish 147 to include a build number or build date. This version string will be 148 included in the output of <code>gcc --version</code>. This suffix does 149 not replace the default version string, only the ‘<samp>GCC</samp>’ part. 150 </p> 151 <p>The default value is ‘<samp>GCC</samp>’. 152 </p> 153 </dd> 154 <dt><code>--with-bugurl=<var>url</var></code></dt> 155 <dd><p>Specify the URL that users should visit if they wish to report a bug. 156 You are of course welcome to forward bugs reported to you to the FSF, 157 if you determine that they are not bugs in your modifications. 158 </p> 159 <p>The default value refers to the FSF’s GCC bug tracker. 160 </p> 161 </dd> 162 </dl> 163 164 <a name="Target-specification"></a> 165 <h3 class="heading">Target specification</h3> 166 <ul> 167 <li> GCC has code to correctly determine the correct value for <var>target</var> 168 for nearly all native systems. Therefore, we highly recommend you do 169 not provide a configure target when configuring a native compiler. 170 171 </li><li> <var>target</var> must be specified as <samp>--target=<var>target</var></samp> 172 when configuring a cross compiler; examples of valid targets would be 173 m68k-elf, sh-elf, etc. 174 175 </li><li> Specifying just <var>target</var> instead of <samp>--target=<var>target</var></samp> 176 implies that the host defaults to <var>target</var>. 177 </li></ul> 178 179 180 <a name="Options-specification"></a> 181 <h3 class="heading">Options specification</h3> 182 183 <p>Use <var>options</var> to override several configure time options for 184 GCC. A list of supported <var>options</var> follows; ‘<samp>configure 185 --help</samp>’ may list other options, but those not listed below may not 186 work and should not normally be used. 187 </p> 188 <p>Note that each <samp>--enable</samp> option has a corresponding 189 <samp>--disable</samp> option and that each <samp>--with</samp> option has a 190 corresponding <samp>--without</samp> option. 191 </p> 192 <dl compact="compact"> 193 <dt><code>--prefix=<var>dirname</var></code></dt> 194 <dd><p>Specify the toplevel installation 195 directory. This is the recommended way to install the tools into a directory 196 other than the default. The toplevel installation directory defaults to 197 <samp>/usr/local</samp>. 198 </p> 199 <p>We <strong>highly</strong> recommend against <var>dirname</var> being the same or a 200 subdirectory of <var>objdir</var> or vice versa. If specifying a directory 201 beneath a user’s home directory tree, some shells will not expand 202 <var>dirname</var> correctly if it contains the ‘<samp>~</samp>’ metacharacter; use 203 <code>$HOME</code> instead. 204 </p> 205 <p>The following standard <code>autoconf</code> options are supported. Normally you 206 should not need to use these options. 207 </p><dl compact="compact"> 208 <dt><code>--exec-prefix=<var>dirname</var></code></dt> 209 <dd><p>Specify the toplevel installation directory for architecture-dependent 210 files. The default is <samp><var>prefix</var></samp>. 211 </p> 212 </dd> 213 <dt><code>--bindir=<var>dirname</var></code></dt> 214 <dd><p>Specify the installation directory for the executables called by users 215 (such as <code>gcc</code> and <code>g++</code>). The default is 216 <samp><var>exec-prefix</var>/bin</samp>. 217 </p> 218 </dd> 219 <dt><code>--libdir=<var>dirname</var></code></dt> 220 <dd><p>Specify the installation directory for object code libraries and 221 internal data files of GCC. The default is <samp><var>exec-prefix</var>/lib</samp>. 222 </p> 223 </dd> 224 <dt><code>--libexecdir=<var>dirname</var></code></dt> 225 <dd><p>Specify the installation directory for internal executables of GCC. 226 The default is <samp><var>exec-prefix</var>/libexec</samp>. 227 </p> 228 </dd> 229 <dt><code>--with-slibdir=<var>dirname</var></code></dt> 230 <dd><p>Specify the installation directory for the shared libgcc library. The 231 default is <samp><var>libdir</var></samp>. 232 </p> 233 </dd> 234 <dt><code>--datarootdir=<var>dirname</var></code></dt> 235 <dd><p>Specify the root of the directory tree for read-only architecture-independent 236 data files referenced by GCC. The default is <samp><var>prefix</var>/share</samp>. 237 </p> 238 </dd> 239 <dt><code>--infodir=<var>dirname</var></code></dt> 240 <dd><p>Specify the installation directory for documentation in info format. 241 The default is <samp><var>datarootdir</var>/info</samp>. 242 </p> 243 </dd> 244 <dt><code>--datadir=<var>dirname</var></code></dt> 245 <dd><p>Specify the installation directory for some architecture-independent 246 data files referenced by GCC. The default is <samp><var>datarootdir</var></samp>. 247 </p> 248 </dd> 249 <dt><code>--docdir=<var>dirname</var></code></dt> 250 <dd><p>Specify the installation directory for documentation files (other 251 than Info) for GCC. The default is <samp><var>datarootdir</var>/doc</samp>. 252 </p> 253 </dd> 254 <dt><code>--htmldir=<var>dirname</var></code></dt> 255 <dd><p>Specify the installation directory for HTML documentation files. 256 The default is <samp><var>docdir</var></samp>. 257 </p> 258 </dd> 259 <dt><code>--pdfdir=<var>dirname</var></code></dt> 260 <dd><p>Specify the installation directory for PDF documentation files. 261 The default is <samp><var>docdir</var></samp>. 262 </p> 263 </dd> 264 <dt><code>--mandir=<var>dirname</var></code></dt> 265 <dd><p>Specify the installation directory for manual pages. The default is 266 <samp><var>datarootdir</var>/man</samp>. (Note that the manual pages are only extracts 267 from the full GCC manuals, which are provided in Texinfo format. The manpages 268 are derived by an automatic conversion process from parts of the full 269 manual.) 270 </p> 271 </dd> 272 <dt><code>--with-gxx-include-dir=<var>dirname</var></code></dt> 273 <dd><p>Specify 274 the installation directory for G++ header files. The default depends 275 on other configuration options, and differs between cross and native 276 configurations. 277 </p> 278 </dd> 279 <dt><code>--with-specs=<var>specs</var></code></dt> 280 <dd><p>Specify additional command line driver SPECS. 281 This can be useful if you need to turn on a non-standard feature by 282 default without modifying the compiler’s source code, for instance 283 <samp>--with-specs=%{!fcommon:%{!fno-common:-fno-common}}</samp>. 284 See “Spec Files” in the main manual 285 </p> 286 </dd> 287 </dl> 288 289 </dd> 290 <dt><code>--program-prefix=<var>prefix</var></code></dt> 291 <dd><p>GCC supports some transformations of the names of its programs when 292 installing them. This option prepends <var>prefix</var> to the names of 293 programs to install in <var>bindir</var> (see above). For example, specifying 294 <samp>--program-prefix=foo-</samp> would result in ‘<samp>gcc</samp>’ 295 being installed as <samp>/usr/local/bin/foo-gcc</samp>. 296 </p> 297 </dd> 298 <dt><code>--program-suffix=<var>suffix</var></code></dt> 299 <dd><p>Appends <var>suffix</var> to the names of programs to install in <var>bindir</var> 300 (see above). For example, specifying <samp>--program-suffix=-3.1</samp> 301 would result in ‘<samp>gcc</samp>’ being installed as 302 <samp>/usr/local/bin/gcc-3.1</samp>. 303 </p> 304 </dd> 305 <dt><code>--program-transform-name=<var>pattern</var></code></dt> 306 <dd><p>Applies the ‘<samp>sed</samp>’ script <var>pattern</var> to be applied to the names 307 of programs to install in <var>bindir</var> (see above). <var>pattern</var> has to 308 consist of one or more basic ‘<samp>sed</samp>’ editing commands, separated by 309 semicolons. For example, if you want the ‘<samp>gcc</samp>’ program name to be 310 transformed to the installed program <samp>/usr/local/bin/myowngcc</samp> and 311 the ‘<samp>g++</samp>’ program name to be transformed to 312 <samp>/usr/local/bin/gspecial++</samp> without changing other program names, 313 you could use the pattern 314 <samp>--program-transform-name='s/^gcc$/myowngcc/; s/^g++$/gspecial++/'</samp> 315 to achieve this effect. 316 </p> 317 <p>All three options can be combined and used together, resulting in more 318 complex conversion patterns. As a basic rule, <var>prefix</var> (and 319 <var>suffix</var>) are prepended (appended) before further transformations 320 can happen with a special transformation script <var>pattern</var>. 321 </p> 322 <p>As currently implemented, this option only takes effect for native 323 builds; cross compiler binaries’ names are not transformed even when a 324 transformation is explicitly asked for by one of these options. 325 </p> 326 <p>For native builds, some of the installed programs are also installed 327 with the target alias in front of their name, as in 328 ‘<samp>i686-pc-linux-gnu-gcc</samp>’. All of the above transformations happen 329 before the target alias is prepended to the name—so, specifying 330 <samp>--program-prefix=foo-</samp> and <samp>program-suffix=-3.1</samp>, the 331 resulting binary would be installed as 332 <samp>/usr/local/bin/i686-pc-linux-gnu-foo-gcc-3.1</samp>. 333 </p> 334 <p>As a last shortcoming, none of the installed Ada programs are 335 transformed yet, which will be fixed in some time. 336 </p> 337 </dd> 338 <dt><code>--with-local-prefix=<var>dirname</var></code></dt> 339 <dd><p>Specify the 340 installation directory for local include files. The default is 341 <samp>/usr/local</samp>. Specify this option if you want the compiler to 342 search directory <samp><var>dirname</var>/include</samp> for locally installed 343 header files <em>instead</em> of <samp>/usr/local/include</samp>. 344 </p> 345 <p>You should specify <samp>--with-local-prefix</samp> <strong>only</strong> if your 346 site has a different convention (not <samp>/usr/local</samp>) for where to put 347 site-specific files. 348 </p> 349 <p>The default value for <samp>--with-local-prefix</samp> is <samp>/usr/local</samp> 350 regardless of the value of <samp>--prefix</samp>. Specifying 351 <samp>--prefix</samp> has no effect on which directory GCC searches for 352 local header files. This may seem counterintuitive, but actually it is 353 logical. 354 </p> 355 <p>The purpose of <samp>--prefix</samp> is to specify where to <em>install 356 GCC</em>. The local header files in <samp>/usr/local/include</samp>—if you put 357 any in that directory—are not part of GCC. They are part of other 358 programs—perhaps many others. (GCC installs its own header files in 359 another directory which is based on the <samp>--prefix</samp> value.) 360 </p> 361 <p>Both the local-prefix include directory and the GCC-prefix include 362 directory are part of GCC’s “system include” directories. Although these 363 two directories are not fixed, they need to be searched in the proper 364 order for the correct processing of the include_next directive. The 365 local-prefix include directory is searched before the GCC-prefix 366 include directory. Another characteristic of system include directories 367 is that pedantic warnings are turned off for headers in these directories. 368 </p> 369 <p>Some autoconf macros add <samp>-I <var>directory</var></samp> options to the 370 compiler command line, to ensure that directories containing installed 371 packages’ headers are searched. When <var>directory</var> is one of GCC’s 372 system include directories, GCC will ignore the option so that system 373 directories continue to be processed in the correct order. This 374 may result in a search order different from what was specified but the 375 directory will still be searched. 376 </p> 377 <p>GCC automatically searches for ordinary libraries using 378 <code>GCC_EXEC_PREFIX</code>. Thus, when the same installation prefix is 379 used for both GCC and packages, GCC will automatically search for 380 both headers and libraries. This provides a configuration that is 381 easy to use. GCC behaves in a manner similar to that when it is 382 installed as a system compiler in <samp>/usr</samp>. 383 </p> 384 <p>Sites that need to install multiple versions of GCC may not want to 385 use the above simple configuration. It is possible to use the 386 <samp>--program-prefix</samp>, <samp>--program-suffix</samp> and 387 <samp>--program-transform-name</samp> options to install multiple versions 388 into a single directory, but it may be simpler to use different prefixes 389 and the <samp>--with-local-prefix</samp> option to specify the location of the 390 site-specific files for each version. It will then be necessary for 391 users to specify explicitly the location of local site libraries 392 (e.g., with <code>LIBRARY_PATH</code>). 393 </p> 394 <p>The same value can be used for both <samp>--with-local-prefix</samp> and 395 <samp>--prefix</samp> provided it is not <samp>/usr</samp>. This can be used 396 to avoid the default search of <samp>/usr/local/include</samp>. 397 </p> 398 <p><strong>Do not</strong> specify <samp>/usr</samp> as the <samp>--with-local-prefix</samp>! 399 The directory you use for <samp>--with-local-prefix</samp> <strong>must not</strong> 400 contain any of the system’s standard header files. If it did contain 401 them, certain programs would be miscompiled (including GNU Emacs, on 402 certain targets), because this would override and nullify the header 403 file corrections made by the <code>fixincludes</code> script. 404 </p> 405 <p>Indications are that people who use this option use it based on mistaken 406 ideas of what it is for. People use it as if it specified where to 407 install part of GCC. Perhaps they make this assumption because 408 installing GCC creates the directory. 409 </p> 410 </dd> 411 <dt><code>--with-gcc-major-version-only</code></dt> 412 <dd><p>Specifies that GCC should use only the major number rather than 413 <var>major</var>.<var>minor</var>.<var>patchlevel</var> in filesystem paths. 414 </p> 415 </dd> 416 <dt><code>--with-native-system-header-dir=<var>dirname</var></code></dt> 417 <dd><p>Specifies that <var>dirname</var> is the directory that contains native system 418 header files, rather than <samp>/usr/include</samp>. This option is most useful 419 if you are creating a compiler that should be isolated from the system 420 as much as possible. It is most commonly used with the 421 <samp>--with-sysroot</samp> option and will cause GCC to search 422 <var>dirname</var> inside the system root specified by that option. 423 </p> 424 </dd> 425 <dt><code>--enable-shared[=<var>package</var>[,…]]</code></dt> 426 <dd><p>Build shared versions of libraries, if shared libraries are supported on 427 the target platform. Unlike GCC 2.95.x and earlier, shared libraries 428 are enabled by default on all platforms that support shared libraries. 429 </p> 430 <p>If a list of packages is given as an argument, build shared libraries 431 only for the listed packages. For other packages, only static libraries 432 will be built. Package names currently recognized in the GCC tree are 433 ‘<samp>libgcc</samp>’ (also known as ‘<samp>gcc</samp>’), ‘<samp>libstdc++</samp>’ (not 434 ‘<samp>libstdc++-v3</samp>’), ‘<samp>libffi</samp>’, ‘<samp>zlib</samp>’, ‘<samp>boehm-gc</samp>’, 435 ‘<samp>ada</samp>’, ‘<samp>libada</samp>’, ‘<samp>libgo</samp>’, ‘<samp>libobjc</samp>’, and ‘<samp>libphobos</samp>’. 436 Note ‘<samp>libiberty</samp>’ does not support shared libraries at all. 437 </p> 438 <p>Use <samp>--disable-shared</samp> to build only static libraries. Note that 439 <samp>--disable-shared</samp> does not accept a list of package names as 440 argument, only <samp>--enable-shared</samp> does. 441 </p> 442 <p>Contrast with <samp>--enable-host-shared</samp>, which affects <em>host</em> 443 code. 444 </p> 445 </dd> 446 <dt><code>--enable-host-shared</code></dt> 447 <dd><p>Specify that the <em>host</em> code should be built into position-independent 448 machine code (with -fPIC), allowing it to be used within shared libraries, 449 but yielding a slightly slower compiler. 450 </p> 451 <p>This option is required when building the libgccjit.so library. 452 </p> 453 <p>Contrast with <samp>--enable-shared</samp>, which affects <em>target</em> 454 libraries. 455 </p> 456 </dd> 457 <dt><code><a name="with-gnu-as"></a>--with-gnu-as</code></dt> 458 <dd><p>Specify that the compiler should assume that the 459 assembler it finds is the GNU assembler. However, this does not modify 460 the rules to find an assembler and will result in confusion if the 461 assembler found is not actually the GNU assembler. (Confusion may also 462 result if the compiler finds the GNU assembler but has not been 463 configured with <samp>--with-gnu-as</samp>.) If you have more than one 464 assembler installed on your system, you may want to use this option in 465 connection with <samp>--with-as=<var>pathname</var></samp> or 466 <samp>--with-build-time-tools=<var>pathname</var></samp>. 467 </p> 468 <p>The following systems are the only ones where it makes a difference 469 whether you use the GNU assembler. On any other system, 470 <samp>--with-gnu-as</samp> has no effect. 471 </p> 472 <ul> 473 <li> ‘<samp>hppa1.0-<var>any</var>-<var>any</var></samp>’ 474 </li><li> ‘<samp>hppa1.1-<var>any</var>-<var>any</var></samp>’ 475 </li><li> ‘<samp>sparc-sun-solaris2.<var>any</var></samp>’ 476 </li><li> ‘<samp>sparc64-<var>any</var>-solaris2.<var>any</var></samp>’ 477 </li></ul> 478 479 </dd> 480 <dt><code><a name="with-as"></a>--with-as=<var>pathname</var></code></dt> 481 <dd><p>Specify that the compiler should use the assembler pointed to by 482 <var>pathname</var>, rather than the one found by the standard rules to find 483 an assembler, which are: 484 </p><ul> 485 <li> Unless GCC is being built with a cross compiler, check the 486 <samp><var>libexec</var>/gcc/<var>target</var>/<var>version</var></samp> directory. 487 <var>libexec</var> defaults to <samp><var>exec-prefix</var>/libexec</samp>; 488 <var>exec-prefix</var> defaults to <var>prefix</var>, which 489 defaults to <samp>/usr/local</samp> unless overridden by the 490 <samp>--prefix=<var>pathname</var></samp> switch described above. <var>target</var> 491 is the target system triple, such as ‘<samp>sparc-sun-solaris2.7</samp>’, and 492 <var>version</var> denotes the GCC version, such as 3.0. 493 494 </li><li> If the target system is the same that you are building on, check 495 operating system specific directories (e.g. <samp>/usr/ccs/bin</samp> on 496 Sun Solaris 2). 497 498 </li><li> Check in the <code>PATH</code> for a tool whose name is prefixed by the 499 target system triple. 500 501 </li><li> Check in the <code>PATH</code> for a tool whose name is not prefixed by the 502 target system triple, if the host and target system triple are 503 the same (in other words, we use a host tool if it can be used for 504 the target as well). 505 </li></ul> 506 507 <p>You may want to use <samp>--with-as</samp> if no assembler 508 is installed in the directories listed above, or if you have multiple 509 assemblers installed and want to choose one that is not found by the 510 above rules. 511 </p> 512 </dd> 513 <dt><code><a name="with-gnu-ld"></a>--with-gnu-ld</code></dt> 514 <dd><p>Same as <a href="#with-gnu-as"><samp>--with-gnu-as</samp></a> 515 but for the linker. 516 </p> 517 </dd> 518 <dt><code>--with-ld=<var>pathname</var></code></dt> 519 <dd><p>Same as <a href="#with-as"><samp>--with-as</samp></a> 520 but for the linker. 521 </p> 522 </dd> 523 <dt><code>--with-stabs</code></dt> 524 <dd><p>Specify that stabs debugging 525 information should be used instead of whatever format the host normally 526 uses. Normally GCC uses the same debug format as the host system. 527 </p> 528 </dd> 529 <dt><code>--with-tls=<var>dialect</var></code></dt> 530 <dd><p>Specify the default TLS dialect, for systems were there is a choice. 531 For ARM targets, possible values for <var>dialect</var> are <code>gnu</code> or 532 <code>gnu2</code>, which select between the original GNU dialect and the GNU TLS 533 descriptor-based dialect. 534 </p> 535 </dd> 536 <dt><code>--enable-multiarch</code></dt> 537 <dd><p>Specify whether to enable or disable multiarch support. The default is 538 to check for glibc start files in a multiarch location, and enable it 539 if the files are found. The auto detection is enabled for native builds, 540 and for cross builds configured with <samp>--with-sysroot</samp>, and without 541 <samp>--with-native-system-header-dir</samp>. 542 More documentation about multiarch can be found at 543 <a href="https://wiki.debian.org/Multiarch">https://wiki.debian.org/Multiarch</a>. 544 </p> 545 </dd> 546 <dt><code>--enable-sjlj-exceptions</code></dt> 547 <dd><p>Force use of the <code>setjmp</code>/<code>longjmp</code>-based scheme for exceptions. 548 ‘<samp>configure</samp>’ ordinarily picks the correct value based on the platform. 549 Only use this option if you are sure you need a different setting. 550 </p> 551 </dd> 552 <dt><code>--enable-vtable-verify</code></dt> 553 <dd><p>Specify whether to enable or disable the vtable verification feature. 554 Enabling this feature causes libstdc++ to be built with its virtual calls 555 in verifiable mode. This means that, when linked with libvtv, every 556 virtual call in libstdc++ will verify the vtable pointer through which the 557 call will be made before actually making the call. If not linked with libvtv, 558 the verifier will call stub functions (in libstdc++ itself) and do nothing. 559 If vtable verification is disabled, then libstdc++ is not built with its 560 virtual calls in verifiable mode at all. However the libvtv library will 561 still be built (see <samp>--disable-libvtv</samp> to turn off building libvtv). 562 <samp>--disable-vtable-verify</samp> is the default. 563 </p> 564 </dd> 565 <dt><code>--disable-gcov</code></dt> 566 <dd><p>Specify that the run-time library used for coverage analysis 567 and associated host tools should not be built. 568 </p> 569 </dd> 570 <dt><code>--disable-multilib</code></dt> 571 <dd><p>Specify that multiple target 572 libraries to support different target variants, calling 573 conventions, etc. should not be built. The default is to build a 574 predefined set of them. 575 </p> 576 <p>Some targets provide finer-grained control over which multilibs are built 577 (e.g., <samp>--disable-softfloat</samp>): 578 </p><dl compact="compact"> 579 <dt><code>arm-*-*</code></dt> 580 <dd><p>fpu, 26bit, underscore, interwork, biendian, nofmult. 581 </p> 582 </dd> 583 <dt><code>m68*-*-*</code></dt> 584 <dd><p>softfloat, m68881, m68000, m68020. 585 </p> 586 </dd> 587 <dt><code>mips*-*-*</code></dt> 588 <dd><p>single-float, biendian, softfloat. 589 </p> 590 </dd> 591 <dt><code>powerpc*-*-*, rs6000*-*-*</code></dt> 592 <dd><p>aix64, pthread, softfloat, powercpu, powerpccpu, powerpcos, biendian, 593 sysv, aix. 594 </p> 595 </dd> 596 </dl> 597 598 </dd> 599 <dt><code>--with-multilib-list=<var>list</var></code></dt> 600 <dt><code>--without-multilib-list</code></dt> 601 <dd><p>Specify what multilibs to build. <var>list</var> is a comma separated list of 602 values, possibly consisting of a single value. Currently only implemented 603 for aarch64*-*-*, arm*-*-*, riscv*-*-*, sh*-*-* and x86-64-*-linux*. The 604 accepted values and meaning for each target is given below. 605 </p> 606 <dl compact="compact"> 607 <dt><code>aarch64*-*-*</code></dt> 608 <dd><p><var>list</var> is a comma separated list of <code>ilp32</code>, and <code>lp64</code> 609 to enable ILP32 and LP64 run-time libraries, respectively. If 610 <var>list</var> is empty, then there will be no multilibs and only the 611 default run-time library will be built. If <var>list</var> is 612 <code>default</code> or –with-multilib-list= is not specified, then the 613 default set of libraries is selected based on the value of 614 <samp>--target</samp>. 615 </p> 616 </dd> 617 <dt><code>arm*-*-*</code></dt> 618 <dd><p><var>list</var> is a comma separated list of <code>aprofile</code> and 619 <code>rmprofile</code> to build multilibs for A or R and M architecture 620 profiles respectively. Note that, due to some limitation of the current 621 multilib framework, using the combined <code>aprofile,rmprofile</code> 622 multilibs selects in some cases a less optimal multilib than when using 623 the multilib profile for the architecture targetted. The special value 624 <code>default</code> is also accepted and is equivalent to omitting the 625 option, i.e., only the default run-time library will be enabled. 626 </p> 627 <p><var>list</var> may instead contain <code>@name</code>, to use the multilib 628 configuration Makefile fragment <samp>name</samp> in <samp>gcc/config/arm</samp> in 629 the source tree (it is part of the corresponding sources, after all). 630 It is recommended, but not required, that files used for this purpose to 631 be named starting with <samp>t-ml-</samp>, to make their intended purpose 632 self-evident, in line with GCC conventions. Such files enable custom, 633 user-chosen multilib lists to be configured. Whether multiple such 634 files can be used together depends on the contents of the supplied 635 files. See <samp>gcc/config/arm/t-multilib</samp> and its supplementary 636 <samp>gcc/config/arm/t-*profile</samp> files for an example of what such 637 Makefile fragments might look like for this version of GCC. The macros 638 expected to be defined in these fragments are not stable across GCC 639 releases, so make sure they define the <code>MULTILIB</code>-related macros 640 expected by the version of GCC you are building. 641 See “Target Makefile Fragments” in the internals manual. 642 </p> 643 <p>The table below gives the combination of ISAs, architectures, FPUs and 644 floating-point ABIs for which multilibs are built for each predefined 645 profile. The union of these options is considered when specifying both 646 <code>aprofile</code> and <code>rmprofile</code>. 647 </p> 648 <table> 649 <tr><td width="15%">Option</td><td width="28%">aprofile</td><td width="30%">rmprofile</td></tr> 650 <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> 651 <tr><td width="15%">Architectures<br><br><br><br><br><br></td><td width="28%">default architecture<br> 652 <code>-march=armv7-a</code><br> 653 <code>-march=armv7ve</code><br> 654 <code>-march=armv8-a</code><br><br><br></td><td width="30%">default architecture<br> 655 <code>-march=armv6s-m</code><br> 656 <code>-march=armv7-m</code><br> 657 <code>-march=armv7e-m</code><br> 658 <code>-march=armv8-m.base</code><br> 659 <code>-march=armv8-m.main</code><br> 660 <code>-march=armv7</code></td></tr> 661 <tr><td width="15%">FPUs<br><br><br><br><br></td><td width="28%">none<br> 662 <code>-mfpu=vfpv3-d16</code><br> 663 <code>-mfpu=neon</code><br> 664 <code>-mfpu=vfpv4-d16</code><br> 665 <code>-mfpu=neon-vfpv4</code><br> 666 <code>-mfpu=neon-fp-armv8</code></td><td width="30%">none<br> 667 <code>-mfpu=vfpv3-d16</code><br> 668 <code>-mfpu=fpv4-sp-d16</code><br> 669 <code>-mfpu=fpv5-sp-d16</code><br> 670 <code>-mfpu=fpv5-d16</code><br></td></tr> 671 <tr><td width="15%">floating-point ABIs<br><br></td><td width="28%"><code>-mfloat-abi=soft</code><br> 672 <code>-mfloat-abi=softfp</code><br> 673 <code>-mfloat-abi=hard</code></td><td width="30%"><code>-mfloat-abi=soft</code><br> 674 <code>-mfloat-abi=softfp</code><br> 675 <code>-mfloat-abi=hard</code></td></tr> 676 </table> 677 678 </dd> 679 <dt><code>riscv*-*-*</code></dt> 680 <dd><p><var>list</var> is a single ABI name. The target architecture must be either 681 <code>rv32gc</code> or <code>rv64gc</code>. This will build a single multilib for the 682 specified architecture and ABI pair. If <code>--with-multilib-list</code> is not 683 given, then a default set of multilibs is selected based on the value of 684 <samp>--target</samp>. This is usually a large set of multilibs. 685 </p> 686 </dd> 687 <dt><code>sh*-*-*</code></dt> 688 <dd><p><var>list</var> is a comma separated list of CPU names. These must be of the 689 form <code>sh*</code> or <code>m*</code> (in which case they match the compiler option 690 for that processor). The list should not contain any endian options - 691 these are handled by <samp>--with-endian</samp>. 692 </p> 693 <p>If <var>list</var> is empty, then there will be no multilibs for extra 694 processors. The multilib for the secondary endian remains enabled. 695 </p> 696 <p>As a special case, if an entry in the list starts with a <code>!</code> 697 (exclamation point), then it is added to the list of excluded multilibs. 698 Entries of this sort should be compatible with ‘<samp>MULTILIB_EXCLUDES</samp>’ 699 (once the leading <code>!</code> has been stripped). 700 </p> 701 <p>If <samp>--with-multilib-list</samp> is not given, then a default set of 702 multilibs is selected based on the value of <samp>--target</samp>. This is 703 usually the complete set of libraries, but some targets imply a more 704 specialized subset. 705 </p> 706 <p>Example 1: to configure a compiler for SH4A only, but supporting both 707 endians, with little endian being the default: 708 </p><div class="smallexample"> 709 <pre class="smallexample">--with-cpu=sh4a --with-endian=little,big --with-multilib-list= 710 </pre></div> 711 712 <p>Example 2: to configure a compiler for both SH4A and SH4AL-DSP, but with 713 only little endian SH4AL: 714 </p><div class="smallexample"> 715 <pre class="smallexample">--with-cpu=sh4a --with-endian=little,big \ 716 --with-multilib-list=sh4al,!mb/m4al 717 </pre></div> 718 719 </dd> 720 <dt><code>x86-64-*-linux*</code></dt> 721 <dd><p><var>list</var> is a comma separated list of <code>m32</code>, <code>m64</code> and 722 <code>mx32</code> to enable 32-bit, 64-bit and x32 run-time libraries, 723 respectively. If <var>list</var> is empty, then there will be no multilibs 724 and only the default run-time library will be enabled. 725 </p> 726 <p>If <samp>--with-multilib-list</samp> is not given, then only 32-bit and 727 64-bit run-time libraries will be enabled. 728 </p></dd> 729 </dl> 730 731 </dd> 732 <dt><code>--with-endian=<var>endians</var></code></dt> 733 <dd><p>Specify what endians to use. 734 Currently only implemented for sh*-*-*. 735 </p> 736 <p><var>endians</var> may be one of the following: 737 </p><dl compact="compact"> 738 <dt><code>big</code></dt> 739 <dd><p>Use big endian exclusively. 740 </p></dd> 741 <dt><code>little</code></dt> 742 <dd><p>Use little endian exclusively. 743 </p></dd> 744 <dt><code>big,little</code></dt> 745 <dd><p>Use big endian by default. Provide a multilib for little endian. 746 </p></dd> 747 <dt><code>little,big</code></dt> 748 <dd><p>Use little endian by default. Provide a multilib for big endian. 749 </p></dd> 750 </dl> 751 752 </dd> 753 <dt><code>--enable-threads</code></dt> 754 <dd><p>Specify that the target 755 supports threads. This affects the Objective-C compiler and runtime 756 library, and exception handling for other languages like C++. 757 On some systems, this is the default. 758 </p> 759 <p>In general, the best (and, in many cases, the only known) threading 760 model available will be configured for use. Beware that on some 761 systems, GCC has not been taught what threading models are generally 762 available for the system. In this case, <samp>--enable-threads</samp> is an 763 alias for <samp>--enable-threads=single</samp>. 764 </p> 765 </dd> 766 <dt><code>--disable-threads</code></dt> 767 <dd><p>Specify that threading support should be disabled for the system. 768 This is an alias for <samp>--enable-threads=single</samp>. 769 </p> 770 </dd> 771 <dt><code>--enable-threads=<var>lib</var></code></dt> 772 <dd><p>Specify that 773 <var>lib</var> is the thread support library. This affects the Objective-C 774 compiler and runtime library, and exception handling for other languages 775 like C++. The possibilities for <var>lib</var> are: 776 </p> 777 <dl compact="compact"> 778 <dt><code>aix</code></dt> 779 <dd><p>AIX thread support. 780 </p></dd> 781 <dt><code>dce</code></dt> 782 <dd><p>DCE thread support. 783 </p></dd> 784 <dt><code>lynx</code></dt> 785 <dd><p>LynxOS thread support. 786 </p></dd> 787 <dt><code>mipssde</code></dt> 788 <dd><p>MIPS SDE thread support. 789 </p></dd> 790 <dt><code>no</code></dt> 791 <dd><p>This is an alias for ‘<samp>single</samp>’. 792 </p></dd> 793 <dt><code>posix</code></dt> 794 <dd><p>Generic POSIX/Unix98 thread support. 795 </p></dd> 796 <dt><code>rtems</code></dt> 797 <dd><p>RTEMS thread support. 798 </p></dd> 799 <dt><code>single</code></dt> 800 <dd><p>Disable thread support, should work for all platforms. 801 </p></dd> 802 <dt><code>tpf</code></dt> 803 <dd><p>TPF thread support. 804 </p></dd> 805 <dt><code>vxworks</code></dt> 806 <dd><p>VxWorks thread support. 807 </p></dd> 808 <dt><code>win32</code></dt> 809 <dd><p>Microsoft Win32 API thread support. 810 </p></dd> 811 </dl> 812 813 </dd> 814 <dt><code>--enable-tls</code></dt> 815 <dd><p>Specify that the target supports TLS (Thread Local Storage). Usually 816 configure can correctly determine if TLS is supported. In cases where 817 it guesses incorrectly, TLS can be explicitly enabled or disabled with 818 <samp>--enable-tls</samp> or <samp>--disable-tls</samp>. This can happen if 819 the assembler supports TLS but the C library does not, or if the 820 assumptions made by the configure test are incorrect. 821 </p> 822 </dd> 823 <dt><code>--disable-tls</code></dt> 824 <dd><p>Specify that the target does not support TLS. 825 This is an alias for <samp>--enable-tls=no</samp>. 826 </p> 827 </dd> 828 <dt><code>--with-cpu=<var>cpu</var></code></dt> 829 <dt><code>--with-cpu-32=<var>cpu</var></code></dt> 830 <dt><code>--with-cpu-64=<var>cpu</var></code></dt> 831 <dd><p>Specify which cpu variant the compiler should generate code for by default. 832 <var>cpu</var> will be used as the default value of the <samp>-mcpu=</samp> switch. 833 This option is only supported on some targets, including ARC, ARM, i386, M68k, 834 PowerPC, and SPARC. It is mandatory for ARC. The <samp>--with-cpu-32</samp> and 835 <samp>--with-cpu-64</samp> options specify separate default CPUs for 836 32-bit and 64-bit modes; these options are only supported for i386, 837 x86-64, PowerPC, and SPARC. 838 </p> 839 </dd> 840 <dt><code>--with-schedule=<var>cpu</var></code></dt> 841 <dt><code>--with-arch=<var>cpu</var></code></dt> 842 <dt><code>--with-arch-32=<var>cpu</var></code></dt> 843 <dt><code>--with-arch-64=<var>cpu</var></code></dt> 844 <dt><code>--with-tune=<var>cpu</var></code></dt> 845 <dt><code>--with-tune-32=<var>cpu</var></code></dt> 846 <dt><code>--with-tune-64=<var>cpu</var></code></dt> 847 <dt><code>--with-abi=<var>abi</var></code></dt> 848 <dt><code>--with-fpu=<var>type</var></code></dt> 849 <dt><code>--with-float=<var>type</var></code></dt> 850 <dd><p>These configure options provide default values for the <samp>-mschedule=</samp>, 851 <samp>-march=</samp>, <samp>-mtune=</samp>, <samp>-mabi=</samp>, and <samp>-mfpu=</samp> 852 options and for <samp>-mhard-float</samp> or <samp>-msoft-float</samp>. As with 853 <samp>--with-cpu</samp>, which switches will be accepted and acceptable values 854 of the arguments depend on the target. 855 </p> 856 </dd> 857 <dt><code>--with-mode=<var>mode</var></code></dt> 858 <dd><p>Specify if the compiler should default to <samp>-marm</samp> or <samp>-mthumb</samp>. 859 This option is only supported on ARM targets. 860 </p> 861 </dd> 862 <dt><code>--with-stack-offset=<var>num</var></code></dt> 863 <dd><p>This option sets the default for the -mstack-offset=<var>num</var> option, 864 and will thus generally also control the setting of this option for 865 libraries. This option is only supported on Epiphany targets. 866 </p> 867 </dd> 868 <dt><code>--with-fpmath=<var>isa</var></code></dt> 869 <dd><p>This options sets <samp>-mfpmath=sse</samp> by default and specifies the default 870 ISA for floating-point arithmetics. You can select either ‘<samp>sse</samp>’ which 871 enables <samp>-msse2</samp> or ‘<samp>avx</samp>’ which enables <samp>-mavx</samp> by default. 872 This option is only supported on i386 and x86-64 targets. 873 </p> 874 </dd> 875 <dt><code>--with-fp-32=<var>mode</var></code></dt> 876 <dd><p>On MIPS targets, set the default value for the <samp>-mfp</samp> option when using 877 the o32 ABI. The possibilities for <var>mode</var> are: 878 </p><dl compact="compact"> 879 <dt><code>32</code></dt> 880 <dd><p>Use the o32 FP32 ABI extension, as with the <samp>-mfp32</samp> command-line 881 option. 882 </p></dd> 883 <dt><code>xx</code></dt> 884 <dd><p>Use the o32 FPXX ABI extension, as with the <samp>-mfpxx</samp> command-line 885 option. 886 </p></dd> 887 <dt><code>64</code></dt> 888 <dd><p>Use the o32 FP64 ABI extension, as with the <samp>-mfp64</samp> command-line 889 option. 890 </p></dd> 891 </dl> 892 <p>In the absence of this configuration option the default is to use the o32 893 FP32 ABI extension. 894 </p> 895 </dd> 896 <dt><code>--with-odd-spreg-32</code></dt> 897 <dd><p>On MIPS targets, set the <samp>-modd-spreg</samp> option by default when using 898 the o32 ABI. 899 </p> 900 </dd> 901 <dt><code>--without-odd-spreg-32</code></dt> 902 <dd><p>On MIPS targets, set the <samp>-mno-odd-spreg</samp> option by default when using 903 the o32 ABI. This is normally used in conjunction with 904 <samp>--with-fp-32=64</samp> in order to target the o32 FP64A ABI extension. 905 </p> 906 </dd> 907 <dt><code>--with-nan=<var>encoding</var></code></dt> 908 <dd><p>On MIPS targets, set the default encoding convention to use for the 909 special not-a-number (NaN) IEEE 754 floating-point data. The 910 possibilities for <var>encoding</var> are: 911 </p><dl compact="compact"> 912 <dt><code>legacy</code></dt> 913 <dd><p>Use the legacy encoding, as with the <samp>-mnan=legacy</samp> command-line 914 option. 915 </p></dd> 916 <dt><code>2008</code></dt> 917 <dd><p>Use the 754-2008 encoding, as with the <samp>-mnan=2008</samp> command-line 918 option. 919 </p></dd> 920 </dl> 921 <p>To use this configuration option you must have an assembler version 922 installed that supports the <samp>-mnan=</samp> command-line option too. 923 In the absence of this configuration option the default convention is 924 the legacy encoding, as when neither of the <samp>-mnan=2008</samp> and 925 <samp>-mnan=legacy</samp> command-line options has been used. 926 </p> 927 </dd> 928 <dt><code>--with-divide=<var>type</var></code></dt> 929 <dd><p>Specify how the compiler should generate code for checking for 930 division by zero. This option is only supported on the MIPS target. 931 The possibilities for <var>type</var> are: 932 </p><dl compact="compact"> 933 <dt><code>traps</code></dt> 934 <dd><p>Division by zero checks use conditional traps (this is the default on 935 systems that support conditional traps). 936 </p></dd> 937 <dt><code>breaks</code></dt> 938 <dd><p>Division by zero checks use the break instruction. 939 </p></dd> 940 </dl> 941 942 943 </dd> 944 <dt><code>--with-llsc</code></dt> 945 <dd><p>On MIPS targets, make <samp>-mllsc</samp> the default when no 946 <samp>-mno-llsc</samp> option is passed. This is the default for 947 Linux-based targets, as the kernel will emulate them if the ISA does 948 not provide them. 949 </p> 950 </dd> 951 <dt><code>--without-llsc</code></dt> 952 <dd><p>On MIPS targets, make <samp>-mno-llsc</samp> the default when no 953 <samp>-mllsc</samp> option is passed. 954 </p> 955 </dd> 956 <dt><code>--with-synci</code></dt> 957 <dd><p>On MIPS targets, make <samp>-msynci</samp> the default when no 958 <samp>-mno-synci</samp> option is passed. 959 </p> 960 </dd> 961 <dt><code>--without-synci</code></dt> 962 <dd><p>On MIPS targets, make <samp>-mno-synci</samp> the default when no 963 <samp>-msynci</samp> option is passed. This is the default. 964 </p> 965 </dd> 966 <dt><code>--with-lxc1-sxc1</code></dt> 967 <dd><p>On MIPS targets, make <samp>-mlxc1-sxc1</samp> the default when no 968 <samp>-mno-lxc1-sxc1</samp> option is passed. This is the default. 969 </p> 970 </dd> 971 <dt><code>--without-lxc1-sxc1</code></dt> 972 <dd><p>On MIPS targets, make <samp>-mno-lxc1-sxc1</samp> the default when no 973 <samp>-mlxc1-sxc1</samp> option is passed. The indexed load/store 974 instructions are not directly a problem but can lead to unexpected 975 behaviour when deployed in an application intended for a 32-bit address 976 space but run on a 64-bit processor. The issue is seen because all 977 known MIPS 64-bit Linux kernels execute o32 and n32 applications 978 with 64-bit addressing enabled which affects the overflow behaviour 979 of the indexed addressing mode. GCC will assume that ordinary 980 32-bit arithmetic overflow behaviour is the same whether performed 981 as an <code>addu</code> instruction or as part of the address calculation 982 in <code>lwxc1</code> type instructions. This assumption holds true in a 983 pure 32-bit environment and can hold true in a 64-bit environment if 984 the address space is accurately set to be 32-bit for o32 and n32. 985 </p> 986 </dd> 987 <dt><code>--with-madd4</code></dt> 988 <dd><p>On MIPS targets, make <samp>-mmadd4</samp> the default when no 989 <samp>-mno-madd4</samp> option is passed. This is the default. 990 </p> 991 </dd> 992 <dt><code>--without-madd4</code></dt> 993 <dd><p>On MIPS targets, make <samp>-mno-madd4</samp> the default when no 994 <samp>-mmadd4</samp> option is passed. The <code>madd4</code> instruction 995 family can be problematic when targeting a combination of cores that 996 implement these instructions differently. There are two known cores 997 that implement these as fused operations instead of unfused (where 998 unfused is normally expected). Disabling these instructions is the 999 only way to ensure compatible code is generated; this will incur 1000 a performance penalty. 1001 </p> 1002 </dd> 1003 <dt><code>--with-mips-plt</code></dt> 1004 <dd><p>On MIPS targets, make use of copy relocations and PLTs. 1005 These features are extensions to the traditional 1006 SVR4-based MIPS ABIs and require support from GNU binutils 1007 and the runtime C library. 1008 </p> 1009 </dd> 1010 <dt><code>--with-stack-clash-protection-guard-size=<var>size</var></code></dt> 1011 <dd><p>On certain targets this option sets the default stack clash protection guard 1012 size as a power of two in bytes. On AArch64 <var>size</var> is required to be either 1013 12 (4KB) or 16 (64KB). 1014 </p> 1015 </dd> 1016 <dt><code>--enable-__cxa_atexit</code></dt> 1017 <dd><p>Define if you want to use __cxa_atexit, rather than atexit, to 1018 register C++ destructors for local statics and global objects. 1019 This is essential for fully standards-compliant handling of 1020 destructors, but requires __cxa_atexit in libc. This option is currently 1021 only available on systems with GNU libc. When enabled, this will cause 1022 <samp>-fuse-cxa-atexit</samp> to be passed by default. 1023 </p> 1024 </dd> 1025 <dt><code>--enable-gnu-indirect-function</code></dt> 1026 <dd><p>Define if you want to enable the <code>ifunc</code> attribute. This option is 1027 currently only available on systems with GNU libc on certain targets. 1028 </p> 1029 </dd> 1030 <dt><code>--enable-target-optspace</code></dt> 1031 <dd><p>Specify that target 1032 libraries should be optimized for code space instead of code speed. 1033 This is the default for the m32r platform. 1034 </p> 1035 </dd> 1036 <dt><code>--with-cpp-install-dir=<var>dirname</var></code></dt> 1037 <dd><p>Specify that the user visible <code>cpp</code> program should be installed 1038 in <samp><var>prefix</var>/<var>dirname</var>/cpp</samp>, in addition to <var>bindir</var>. 1039 </p> 1040 </dd> 1041 <dt><code>--enable-comdat</code></dt> 1042 <dd><p>Enable COMDAT group support. This is primarily used to override the 1043 automatically detected value. 1044 </p> 1045 </dd> 1046 <dt><code>--enable-initfini-array</code></dt> 1047 <dd><p>Force the use of sections <code>.init_array</code> and <code>.fini_array</code> 1048 (instead of <code>.init</code> and <code>.fini</code>) for constructors and 1049 destructors. Option <samp>--disable-initfini-array</samp> has the 1050 opposite effect. If neither option is specified, the configure script 1051 will try to guess whether the <code>.init_array</code> and 1052 <code>.fini_array</code> sections are supported and, if they are, use them. 1053 </p> 1054 </dd> 1055 <dt><code>--enable-link-mutex</code></dt> 1056 <dd><p>When building GCC, use a mutex to avoid linking the compilers for 1057 multiple languages at the same time, to avoid thrashing on build 1058 systems with limited free memory. The default is not to use such a mutex. 1059 </p> 1060 </dd> 1061 <dt><code>--enable-maintainer-mode</code></dt> 1062 <dd><p>The build rules that regenerate the Autoconf and Automake output files as 1063 well as the GCC master message catalog <samp>gcc.pot</samp> are normally 1064 disabled. This is because it can only be rebuilt if the complete source 1065 tree is present. If you have changed the sources and want to rebuild the 1066 catalog, configuring with <samp>--enable-maintainer-mode</samp> will enable 1067 this. Note that you need a recent version of the <code>gettext</code> tools 1068 to do so. 1069 </p> 1070 </dd> 1071 <dt><code>--disable-bootstrap</code></dt> 1072 <dd><p>For a native build, the default configuration is to perform 1073 a 3-stage bootstrap of the compiler when ‘<samp>make</samp>’ is invoked, 1074 testing that GCC can compile itself correctly. If you want to disable 1075 this process, you can configure with <samp>--disable-bootstrap</samp>. 1076 </p> 1077 </dd> 1078 <dt><code>--enable-bootstrap</code></dt> 1079 <dd><p>In special cases, you may want to perform a 3-stage build 1080 even if the target and host triplets are different. 1081 This is possible when the host can run code compiled for 1082 the target (e.g. host is i686-linux, target is i486-linux). 1083 Starting from GCC 4.2, to do this you have to configure explicitly 1084 with <samp>--enable-bootstrap</samp>. 1085 </p> 1086 </dd> 1087 <dt><code>--enable-generated-files-in-srcdir</code></dt> 1088 <dd><p>Neither the .c and .h files that are generated from Bison and flex nor the 1089 info manuals and man pages that are built from the .texi files are present 1090 in the repository development tree. When building GCC from that development tree, 1091 or from one of our snapshots, those generated files are placed in your 1092 build directory, which allows for the source to be in a readonly 1093 directory. 1094 </p> 1095 <p>If you configure with <samp>--enable-generated-files-in-srcdir</samp> then those 1096 generated files will go into the source directory. This is mainly intended 1097 for generating release or prerelease tarballs of the GCC sources, since it 1098 is not a requirement that the users of source releases to have flex, Bison, 1099 or makeinfo. 1100 </p> 1101 </dd> 1102 <dt><code>--enable-version-specific-runtime-libs</code></dt> 1103 <dd><p>Specify 1104 that runtime libraries should be installed in the compiler specific 1105 subdirectory (<samp><var>libdir</var>/gcc</samp>) rather than the usual places. In 1106 addition, ‘<samp>libstdc++</samp>’’s include files will be installed into 1107 <samp><var>libdir</var></samp> unless you overruled it by using 1108 <samp>--with-gxx-include-dir=<var>dirname</var></samp>. Using this option is 1109 particularly useful if you intend to use several versions of GCC in 1110 parallel. This is currently supported by ‘<samp>libgfortran</samp>’, 1111 ‘<samp>libstdc++</samp>’, and ‘<samp>libobjc</samp>’. 1112 </p> 1113 </dd> 1114 <dt><code><a name="WithAixSoname"></a>--with-aix-soname=‘<samp>aix</samp>’, ‘<samp>svr4</samp>’ or ‘<samp>both</samp>’</code></dt> 1115 <dd><p>Traditional AIX shared library versioning (versioned <code>Shared Object</code> 1116 files as members of unversioned <code>Archive Library</code> files named 1117 ‘<samp>lib.a</samp>’) causes numerous headaches for package managers. However, 1118 <code>Import Files</code> as members of <code>Archive Library</code> files allow for 1119 <strong>filename-based versioning</strong> of shared libraries as seen on Linux/SVR4, 1120 where this is called the "SONAME". But as they prevent static linking, 1121 <code>Import Files</code> may be used with <code>Runtime Linking</code> only, where the 1122 linker does search for ‘<samp>libNAME.so</samp>’ before ‘<samp>libNAME.a</samp>’ library 1123 filenames with the ‘<samp>-lNAME</samp>’ linker flag. 1124 </p> 1125 <a name="AixLdCommand"></a><p>For detailed information please refer to the AIX 1126 <a href="https://www.ibm.com/support/knowledgecenter/search/%22the%20ld%20command%2C%20also%20called%20the%20linkage%20editor%20or%20binder%22">ld 1127 Command</a> reference. 1128 </p> 1129 <p>As long as shared library creation is enabled, upon: 1130 </p><dl compact="compact"> 1131 <dt><code>--with-aix-soname=aix</code></dt> 1132 <dt><code>--with-aix-soname=both</code></dt> 1133 <dd><p>A (traditional AIX) <code>Shared Archive Library</code> file is created: 1134 </p><ul> 1135 <li> using the ‘<samp>libNAME.a</samp>’ filename scheme 1136 </li><li> with the <code>Shared Object</code> file as archive member named 1137 ‘<samp>libNAME.so.V</samp>’ (except for ‘<samp>libgcc_s</samp>’, where the <code>Shared 1138 Object</code> file is named ‘<samp>shr.o</samp>’ for backwards compatibility), which 1139 <ul class="no-bullet"> 1140 <li>- is used for runtime loading from inside the ‘<samp>libNAME.a</samp>’ file 1141 </li><li>- is used for dynamic loading via 1142 <code>dlopen("libNAME.a(libNAME.so.V)", RTLD_MEMBER)</code> 1143 </li><li>- is used for shared linking 1144 </li><li>- is used for static linking, so no separate <code>Static Archive 1145 Library</code> file is needed 1146 </li></ul> 1147 </li></ul> 1148 </dd> 1149 <dt><code>--with-aix-soname=both</code></dt> 1150 <dt><code>--with-aix-soname=svr4</code></dt> 1151 <dd><p>A (second) <code>Shared Archive Library</code> file is created: 1152 </p><ul> 1153 <li> using the ‘<samp>libNAME.so.V</samp>’ filename scheme 1154 </li><li> with the <code>Shared Object</code> file as archive member named 1155 ‘<samp>shr.o</samp>’, which 1156 <ul class="no-bullet"> 1157 <li>- is created with the <code>-G linker flag</code> 1158 </li><li>- has the <code>F_LOADONLY</code> flag set 1159 </li><li>- is used for runtime loading from inside the ‘<samp>libNAME.so.V</samp>’ file 1160 </li><li>- is used for dynamic loading via <code>dlopen("libNAME.so.V(shr.o)", 1161 RTLD_MEMBER)</code> 1162 </li></ul> 1163 </li><li> with the <code>Import File</code> as archive member named ‘<samp>shr.imp</samp>’, 1164 which 1165 <ul class="no-bullet"> 1166 <li>- refers to ‘<samp>libNAME.so.V(shr.o)</samp>’ as the "SONAME", to be recorded 1167 in the <code>Loader Section</code> of subsequent binaries 1168 </li><li>- indicates whether ‘<samp>libNAME.so.V(shr.o)</samp>’ is 32 or 64 bit 1169 </li><li>- lists all the public symbols exported by ‘<samp>lib.so.V(shr.o)</samp>’, 1170 eventually decorated with the <code>‘<samp>weak</samp>’ Keyword</code> 1171 </li><li>- is necessary for shared linking against ‘<samp>lib.so.V(shr.o)</samp>’ 1172 </li></ul> 1173 </li></ul> 1174 <p>A symbolic link using the ‘<samp>libNAME.so</samp>’ filename scheme is created: 1175 </p><ul> 1176 <li> pointing to the ‘<samp>libNAME.so.V</samp>’ <code>Shared Archive Library</code> file 1177 </li><li> to permit the <code>ld Command</code> to find ‘<samp>lib.so.V(shr.imp)</samp>’ via 1178 the ‘<samp>-lNAME</samp>’ argument (requires <code>Runtime Linking</code> to be enabled) 1179 </li><li> to permit dynamic loading of ‘<samp>lib.so.V(shr.o)</samp>’ without the need 1180 to specify the version number via <code>dlopen("libNAME.so(shr.o)", 1181 RTLD_MEMBER)</code> 1182 </li></ul> 1183 </dd> 1184 </dl> 1185 1186 <p>As long as static library creation is enabled, upon: 1187 </p><dl compact="compact"> 1188 <dt><code>--with-aix-soname=svr4</code></dt> 1189 <dd><p>A <code>Static Archive Library</code> is created: 1190 </p><ul> 1191 <li> using the ‘<samp>libNAME.a</samp>’ filename scheme 1192 </li><li> with all the <code>Static Object</code> files as archive members, which 1193 <ul class="no-bullet"> 1194 <li>- are used for static linking 1195 </li></ul> 1196 </li></ul> 1197 </dd> 1198 </dl> 1199 1200 <p>While the aix-soname=‘<samp>svr4</samp>’ option does not create <code>Shared Object</code> 1201 files as members of unversioned <code>Archive Library</code> files any more, package 1202 managers still are responsible to 1203 <a href="./specific.html#TransferAixShobj">transfer</a> <code>Shared Object</code> files 1204 found as member of a previously installed unversioned <code>Archive Library</code> 1205 file into the newly installed <code>Archive Library</code> file with the same 1206 filename. 1207 </p> 1208 <p><em>WARNING:</em> Creating <code>Shared Object</code> files with <code>Runtime Linking</code> 1209 enabled may bloat the TOC, eventually leading to <code>TOC overflow</code> errors, 1210 requiring the use of either the <samp>-Wl,-bbigtoc</samp> linker flag (seen to 1211 break with the <code>GDB</code> debugger) or some of the TOC-related compiler flags, 1212 see “RS/6000 and PowerPC Options” in the main manual. 1213 </p> 1214 <p><samp>--with-aix-soname</samp> is currently supported by ‘<samp>libgcc_s</samp>’ only, so 1215 this option is still experimental and not for normal use yet. 1216 </p> 1217 <p>Default is the traditional behavior <samp>--with-aix-soname=‘<samp>aix</samp>’</samp>. 1218 </p> 1219 </dd> 1220 <dt><code>--enable-languages=<var>lang1</var>,<var>lang2</var>,…</code></dt> 1221 <dd><p>Specify that only a particular subset of compilers and 1222 their runtime libraries should be built. For a list of valid values for 1223 <var>langN</var> you can issue the following command in the 1224 <samp>gcc</samp> directory of your GCC source tree:<br> 1225 </p><div class="smallexample"> 1226 <pre class="smallexample">grep ^language= */config-lang.in 1227 </pre></div> 1228 <p>Currently, you can use any of the following: 1229 <code>all</code>, <code>default</code>, <code>ada</code>, <code>c</code>, <code>c++</code>, <code>d</code>, 1230 <code>fortran</code>, <code>go</code>, <code>jit</code>, <code>lto</code>, <code>objc</code>, <code>obj-c++</code>. 1231 Building the Ada compiler has special requirements, see below. 1232 If you do not pass this flag, or specify the option <code>default</code>, then the 1233 default languages available in the <samp>gcc</samp> sub-tree will be configured. 1234 Ada, D, Go, Jit, and Objective-C++ are not default languages. LTO is not a 1235 default language, but is built by default because <samp>--enable-lto</samp> is 1236 enabled by default. The other languages are default languages. If 1237 <code>all</code> is specified, then all available languages are built. An 1238 exception is <code>jit</code> language, which requires 1239 <samp>--enable-host-shared</samp> to be included with <code>all</code>. 1240 </p> 1241 </dd> 1242 <dt><code>--enable-stage1-languages=<var>lang1</var>,<var>lang2</var>,…</code></dt> 1243 <dd><p>Specify that a particular subset of compilers and their runtime 1244 libraries should be built with the system C compiler during stage 1 of 1245 the bootstrap process, rather than only in later stages with the 1246 bootstrapped C compiler. The list of valid values is the same as for 1247 <samp>--enable-languages</samp>, and the option <code>all</code> will select all 1248 of the languages enabled by <samp>--enable-languages</samp>. This option is 1249 primarily useful for GCC development; for instance, when a development 1250 version of the compiler cannot bootstrap due to compiler bugs, or when 1251 one is debugging front ends other than the C front end. When this 1252 option is used, one can then build the target libraries for the 1253 specified languages with the stage-1 compiler by using <code>make 1254 stage1-bubble all-target</code>, or run the testsuite on the stage-1 compiler 1255 for the specified languages using <code>make stage1-start check-gcc</code>. 1256 </p> 1257 </dd> 1258 <dt><code>--disable-libada</code></dt> 1259 <dd><p>Specify that the run-time libraries and tools used by GNAT should not 1260 be built. This can be useful for debugging, or for compatibility with 1261 previous Ada build procedures, when it was required to explicitly 1262 do a ‘<samp>make -C gcc gnatlib_and_tools</samp>’. 1263 </p> 1264 </dd> 1265 <dt><code>--disable-libsanitizer</code></dt> 1266 <dd><p>Specify that the run-time libraries for the various sanitizers should 1267 not be built. 1268 </p> 1269 </dd> 1270 <dt><code>--disable-libssp</code></dt> 1271 <dd><p>Specify that the run-time libraries for stack smashing protection 1272 should not be built or linked against. On many targets library support 1273 is provided by the C library instead. 1274 </p> 1275 </dd> 1276 <dt><code>--disable-libquadmath</code></dt> 1277 <dd><p>Specify that the GCC quad-precision math library should not be built. 1278 On some systems, the library is required to be linkable when building 1279 the Fortran front end, unless <samp>--disable-libquadmath-support</samp> 1280 is used. 1281 </p> 1282 </dd> 1283 <dt><code>--disable-libquadmath-support</code></dt> 1284 <dd><p>Specify that the Fortran front end and <code>libgfortran</code> do not add 1285 support for <code>libquadmath</code> on systems supporting it. 1286 </p> 1287 </dd> 1288 <dt><code>--disable-libgomp</code></dt> 1289 <dd><p>Specify that the GNU Offloading and Multi Processing Runtime Library 1290 should not be built. 1291 </p> 1292 </dd> 1293 <dt><code>--disable-libvtv</code></dt> 1294 <dd><p>Specify that the run-time libraries used by vtable verification 1295 should not be built. 1296 </p> 1297 </dd> 1298 <dt><code>--with-dwarf2</code></dt> 1299 <dd><p>Specify that the compiler should 1300 use DWARF 2 debugging information as the default. 1301 </p> 1302 </dd> 1303 <dt><code>--with-advance-toolchain=<var>at</var></code></dt> 1304 <dd><p>On 64-bit PowerPC Linux systems, configure the compiler to use the 1305 header files, library files, and the dynamic linker from the Advance 1306 Toolchain release <var>at</var> instead of the default versions that are 1307 provided by the Linux distribution. In general, this option is 1308 intended for the developers of GCC, and it is not intended for general 1309 use. 1310 </p> 1311 </dd> 1312 <dt><code>--enable-targets=all</code></dt> 1313 <dt><code>--enable-targets=<var>target_list</var></code></dt> 1314 <dd><p>Some GCC targets, e.g. powerpc64-linux, build bi-arch compilers. 1315 These are compilers that are able to generate either 64-bit or 32-bit 1316 code. Typically, the corresponding 32-bit target, e.g. 1317 powerpc-linux for powerpc64-linux, only generates 32-bit code. This 1318 option enables the 32-bit target to be a bi-arch compiler, which is 1319 useful when you want a bi-arch compiler that defaults to 32-bit, and 1320 you are building a bi-arch or multi-arch binutils in a combined tree. 1321 On mips-linux, this will build a tri-arch compiler (ABI o32/n32/64), 1322 defaulted to o32. 1323 Currently, this option only affects sparc-linux, powerpc-linux, x86-linux, 1324 mips-linux and s390-linux. 1325 </p> 1326 </dd> 1327 <dt><code>--enable-default-pie</code></dt> 1328 <dd><p>Turn on <samp>-fPIE</samp> and <samp>-pie</samp> by default. 1329 </p> 1330 </dd> 1331 <dt><code>--enable-secureplt</code></dt> 1332 <dd><p>This option enables <samp>-msecure-plt</samp> by default for powerpc-linux. 1333 See “RS/6000 and PowerPC Options” in the main manual 1334 </p> 1335 </dd> 1336 <dt><code>--enable-default-ssp</code></dt> 1337 <dd><p>Turn on <samp>-fstack-protector-strong</samp> by default. 1338 </p> 1339 </dd> 1340 <dt><code>--enable-cld</code></dt> 1341 <dd><p>This option enables <samp>-mcld</samp> by default for 32-bit x86 targets. 1342 See “i386 and x86-64 Options” in the main manual 1343 </p> 1344 </dd> 1345 <dt><code>--enable-large-address-aware</code></dt> 1346 <dd><p>The <samp>--enable-large-address-aware</samp> option arranges for MinGW 1347 executables to be linked using the <samp>--large-address-aware</samp> 1348 option, that enables the use of more than 2GB of memory. If GCC is 1349 configured with this option, its effects can be reversed by passing the 1350 <samp>-Wl,--disable-large-address-aware</samp> option to the so-configured 1351 compiler driver. 1352 </p> 1353 </dd> 1354 <dt><code>--enable-win32-registry</code></dt> 1355 <dt><code>--enable-win32-registry=<var>key</var></code></dt> 1356 <dt><code>--disable-win32-registry</code></dt> 1357 <dd><p>The <samp>--enable-win32-registry</samp> option enables Microsoft Windows-hosted GCC 1358 to look up installations paths in the registry using the following key: 1359 </p> 1360 <div class="smallexample"> 1361 <pre class="smallexample"><code>HKEY_LOCAL_MACHINE\SOFTWARE\Free Software Foundation\<var>key</var></code> 1362 </pre></div> 1363 1364 <p><var>key</var> defaults to GCC version number, and can be overridden by the 1365 <samp>--enable-win32-registry=<var>key</var></samp> option. Vendors and distributors 1366 who use custom installers are encouraged to provide a different key, 1367 perhaps one comprised of vendor name and GCC version number, to 1368 avoid conflict with existing installations. This feature is enabled 1369 by default, and can be disabled by <samp>--disable-win32-registry</samp> 1370 option. This option has no effect on the other hosts. 1371 </p> 1372 </dd> 1373 <dt><code>--nfp</code></dt> 1374 <dd><p>Specify that the machine does not have a floating point unit. This 1375 option only applies to ‘<samp>m68k-sun-sunos<var>n</var></samp>’. On any other 1376 system, <samp>--nfp</samp> has no effect. 1377 </p> 1378 </dd> 1379 <dt><code>--enable-werror</code></dt> 1380 <dt><code>--disable-werror</code></dt> 1381 <dt><code>--enable-werror=yes</code></dt> 1382 <dt><code>--enable-werror=no</code></dt> 1383 <dd><p>When you specify this option, it controls whether certain files in the 1384 compiler are built with <samp>-Werror</samp> in bootstrap stage2 and later. 1385 If you don’t specify it, <samp>-Werror</samp> is turned on for the main 1386 development trunk. However it defaults to off for release branches and 1387 final releases. The specific files which get <samp>-Werror</samp> are 1388 controlled by the Makefiles. 1389 </p> 1390 </dd> 1391 <dt><code>--enable-checking</code></dt> 1392 <dt><code>--disable-checking</code></dt> 1393 <dt><code>--enable-checking=<var>list</var></code></dt> 1394 <dd><p>This option controls performing internal consistency checks in the compiler. 1395 It does not change the generated code, but adds error checking of the 1396 requested complexity. This slows down the compiler and may only work 1397 properly if you are building the compiler with GCC. 1398 </p> 1399 <p>When the option is not specified, the active set of checks depends on context. 1400 Namely, bootstrap stage 1 defaults to ‘<samp>--enable-checking=yes</samp>’, builds 1401 from release branches or release archives default to 1402 ‘<samp>--enable-checking=release</samp>’, and otherwise 1403 ‘<samp>--enable-checking=yes,extra</samp>’ is used. When the option is 1404 specified without a <var>list</var>, the result is the same as 1405 ‘<samp>--enable-checking=yes</samp>’. Likewise, ‘<samp>--disable-checking</samp>’ is 1406 equivalent to ‘<samp>--enable-checking=no</samp>’. 1407 </p> 1408 <p>The categories of checks available in <var>list</var> are ‘<samp>yes</samp>’ (most common 1409 checks ‘<samp>assert,misc,gc,gimple,rtlflag,runtime,tree,types</samp>’), ‘<samp>no</samp>’ 1410 (no checks at all), ‘<samp>all</samp>’ (all but ‘<samp>valgrind</samp>’), ‘<samp>release</samp>’ 1411 (cheapest checks ‘<samp>assert,runtime</samp>’) or ‘<samp>none</samp>’ (same as ‘<samp>no</samp>’). 1412 ‘<samp>release</samp>’ checks are always on and to disable them 1413 ‘<samp>--disable-checking</samp>’ or ‘<samp>--enable-checking=no[,<other checks>]</samp>’ 1414 must be explicitly requested. Disabling assertions makes the compiler and 1415 runtime slightly faster but increases the risk of undetected internal errors 1416 causing wrong code to be generated. 1417 </p> 1418 <p>Individual checks can be enabled with these flags: ‘<samp>assert</samp>’, ‘<samp>df</samp>’, 1419 ‘<samp>extra</samp>’, ‘<samp>fold</samp>’, ‘<samp>gc</samp>’, ‘<samp>gcac</samp>’, ‘<samp>gimple</samp>’, 1420 ‘<samp>misc</samp>’, ‘<samp>rtl</samp>’, ‘<samp>rtlflag</samp>’, ‘<samp>runtime</samp>’, ‘<samp>tree</samp>’, 1421 ‘<samp>types</samp>’ and ‘<samp>valgrind</samp>’. ‘<samp>extra</samp>’ extends ‘<samp>misc</samp>’ 1422 checking with extra checks that might affect code generation and should 1423 therefore not differ between stage1 and later stages in bootstrap. 1424 </p> 1425 <p>The ‘<samp>valgrind</samp>’ check requires the external <code>valgrind</code> simulator, 1426 available from <a href="http://valgrind.org/">http://valgrind.org/</a>. The ‘<samp>rtl</samp>’ checks are 1427 expensive and the ‘<samp>df</samp>’, ‘<samp>gcac</samp>’ and ‘<samp>valgrind</samp>’ checks are very 1428 expensive. 1429 </p> 1430 </dd> 1431 <dt><code>--disable-stage1-checking</code></dt> 1432 <dt><code>--enable-stage1-checking</code></dt> 1433 <dt><code>--enable-stage1-checking=<var>list</var></code></dt> 1434 <dd><p>This option affects only bootstrap build. If no <samp>--enable-checking</samp> 1435 option is specified the stage1 compiler is built with ‘<samp>yes</samp>’ checking 1436 enabled, otherwise the stage1 checking flags are the same as specified by 1437 <samp>--enable-checking</samp>. To build the stage1 compiler with 1438 different checking options use <samp>--enable-stage1-checking</samp>. 1439 The list of checking options is the same as for <samp>--enable-checking</samp>. 1440 If your system is too slow or too small to bootstrap a released compiler 1441 with checking for stage1 enabled, you can use ‘<samp>--disable-stage1-checking</samp>’ 1442 to disable checking for the stage1 compiler. 1443 </p> 1444 </dd> 1445 <dt><code>--enable-coverage</code></dt> 1446 <dt><code>--enable-coverage=<var>level</var></code></dt> 1447 <dd><p>With this option, the compiler is built to collect self coverage 1448 information, every time it is run. This is for internal development 1449 purposes, and only works when the compiler is being built with gcc. The 1450 <var>level</var> argument controls whether the compiler is built optimized or 1451 not, values are ‘<samp>opt</samp>’ and ‘<samp>noopt</samp>’. For coverage analysis you 1452 want to disable optimization, for performance analysis you want to 1453 enable optimization. When coverage is enabled, the default level is 1454 without optimization. 1455 </p> 1456 </dd> 1457 <dt><code>--enable-gather-detailed-mem-stats</code></dt> 1458 <dd><p>When this option is specified more detailed information on memory 1459 allocation is gathered. This information is printed when using 1460 <samp>-fmem-report</samp>. 1461 </p> 1462 </dd> 1463 <dt><code>--enable-valgrind-annotations</code></dt> 1464 <dd><p>Mark selected memory related operations in the compiler when run under 1465 valgrind to suppress false positives. 1466 </p> 1467 </dd> 1468 <dt><code>--enable-nls</code></dt> 1469 <dt><code>--disable-nls</code></dt> 1470 <dd><p>The <samp>--enable-nls</samp> option enables Native Language Support (NLS), 1471 which lets GCC output diagnostics in languages other than American 1472 English. Native Language Support is enabled by default if not doing a 1473 canadian cross build. The <samp>--disable-nls</samp> option disables NLS. 1474 </p> 1475 </dd> 1476 <dt><code>--with-included-gettext</code></dt> 1477 <dd><p>If NLS is enabled, the <samp>--with-included-gettext</samp> option causes the build 1478 procedure to prefer its copy of GNU <code>gettext</code>. 1479 </p> 1480 </dd> 1481 <dt><code>--with-catgets</code></dt> 1482 <dd><p>If NLS is enabled, and if the host lacks <code>gettext</code> but has the 1483 inferior <code>catgets</code> interface, the GCC build procedure normally 1484 ignores <code>catgets</code> and instead uses GCC’s copy of the GNU 1485 <code>gettext</code> library. The <samp>--with-catgets</samp> option causes the 1486 build procedure to use the host’s <code>catgets</code> in this situation. 1487 </p> 1488 </dd> 1489 <dt><code>--with-libiconv-prefix=<var>dir</var></code></dt> 1490 <dd><p>Search for libiconv header files in <samp><var>dir</var>/include</samp> and 1491 libiconv library files in <samp><var>dir</var>/lib</samp>. 1492 </p> 1493 </dd> 1494 <dt><code>--enable-obsolete</code></dt> 1495 <dd><p>Enable configuration for an obsoleted system. If you attempt to 1496 configure GCC for a system (build, host, or target) which has been 1497 obsoleted, and you do not specify this flag, configure will halt with an 1498 error message. 1499 </p> 1500 <p>All support for systems which have been obsoleted in one release of GCC 1501 is removed entirely in the next major release, unless someone steps 1502 forward to maintain the port. 1503 </p> 1504 </dd> 1505 <dt><code>--enable-decimal-float</code></dt> 1506 <dt><code>--enable-decimal-float=yes</code></dt> 1507 <dt><code>--enable-decimal-float=no</code></dt> 1508 <dt><code>--enable-decimal-float=bid</code></dt> 1509 <dt><code>--enable-decimal-float=dpd</code></dt> 1510 <dt><code>--disable-decimal-float</code></dt> 1511 <dd><p>Enable (or disable) support for the C decimal floating point extension 1512 that is in the IEEE 754-2008 standard. This is enabled by default only 1513 on PowerPC, i386, and x86_64 GNU/Linux systems. Other systems may also 1514 support it, but require the user to specifically enable it. You can 1515 optionally control which decimal floating point format is used (either 1516 ‘<samp>bid</samp>’ or ‘<samp>dpd</samp>’). The ‘<samp>bid</samp>’ (binary integer decimal) 1517 format is default on i386 and x86_64 systems, and the ‘<samp>dpd</samp>’ 1518 (densely packed decimal) format is default on PowerPC systems. 1519 </p> 1520 </dd> 1521 <dt><code>--enable-fixed-point</code></dt> 1522 <dt><code>--disable-fixed-point</code></dt> 1523 <dd><p>Enable (or disable) support for C fixed-point arithmetic. 1524 This option is enabled by default for some targets (such as MIPS) which 1525 have hardware-support for fixed-point operations. On other targets, you 1526 may enable this option manually. 1527 </p> 1528 </dd> 1529 <dt><code>--with-long-double-128</code></dt> 1530 <dd><p>Specify if <code>long double</code> type should be 128-bit by default on selected 1531 GNU/Linux architectures. If using <code>--without-long-double-128</code>, 1532 <code>long double</code> will be by default 64-bit, the same as <code>double</code> type. 1533 When neither of these configure options are used, the default will be 1534 128-bit <code>long double</code> when built against GNU C Library 2.4 and later, 1535 64-bit <code>long double</code> otherwise. 1536 </p> 1537 </dd> 1538 <dt><code>--with-long-double-format=ibm</code></dt> 1539 <dt><code>--with-long-double-format=ieee</code></dt> 1540 <dd><p>Specify whether <code>long double</code> uses the IBM extended double format 1541 or the IEEE 128-bit floating point format on PowerPC Linux systems. 1542 This configuration switch will only work on little endian PowerPC 1543 Linux systems and on big endian 64-bit systems where the default cpu 1544 is at least power7 (i.e. <samp>--with-cpu=power7</samp>, 1545 <samp>--with-cpu=power8</samp>, or <samp>--with-cpu=power9</samp> is used). 1546 </p> 1547 <p>If you use the <samp>--with-long-double-64</samp> configuration option, 1548 the <samp>--with-long-double-format=ibm</samp> and 1549 <samp>--with-long-double-format=ieee</samp> options are ignored. 1550 </p> 1551 <p>The default <code>long double</code> format is to use IBM extended double. 1552 Until all of the libraries are converted to use IEEE 128-bit floating 1553 point, it is not recommended to use 1554 <samp>--with-long-double-format=ieee</samp>. 1555 </p> 1556 <p>On little endian PowerPC Linux systems, if you explicitly set the 1557 <code>long double</code> type, it will build multilibs to allow you to 1558 select either <code>long double</code> format, unless you disable multilibs 1559 with the <code>--disable-multilib</code> option. At present, 1560 <code>long double</code> multilibs are not built on big endian PowerPC Linux 1561 systems. If you are building multilibs, you will need to configure 1562 the compiler using the <samp>--with-system-zlib</samp> option. 1563 </p> 1564 <p>If you do not set the <code>long double</code> type explicitly, no multilibs 1565 will be generated. 1566 </p> 1567 </dd> 1568 <dt><code>--enable-fdpic</code></dt> 1569 <dd><p>On SH Linux systems, generate ELF FDPIC code. 1570 </p> 1571 </dd> 1572 <dt><code>--with-gmp=<var>pathname</var></code></dt> 1573 <dt><code>--with-gmp-include=<var>pathname</var></code></dt> 1574 <dt><code>--with-gmp-lib=<var>pathname</var></code></dt> 1575 <dt><code>--with-mpfr=<var>pathname</var></code></dt> 1576 <dt><code>--with-mpfr-include=<var>pathname</var></code></dt> 1577 <dt><code>--with-mpfr-lib=<var>pathname</var></code></dt> 1578 <dt><code>--with-mpc=<var>pathname</var></code></dt> 1579 <dt><code>--with-mpc-include=<var>pathname</var></code></dt> 1580 <dt><code>--with-mpc-lib=<var>pathname</var></code></dt> 1581 <dd><p>If you want to build GCC but do not have the GMP library, the MPFR 1582 library and/or the MPC library installed in a standard location and 1583 do not have their sources present in the GCC source tree then you 1584 can explicitly specify the directory where they are installed 1585 (‘<samp>--with-gmp=<var>gmpinstalldir</var></samp>’, 1586 ‘<samp>--with-mpfr=<var>mpfrinstalldir</var></samp>’, 1587 ‘<samp>--with-mpc=<var>mpcinstalldir</var></samp>’). The 1588 <samp>--with-gmp=<var>gmpinstalldir</var></samp> option is shorthand for 1589 <samp>--with-gmp-lib=<var>gmpinstalldir</var>/lib</samp> and 1590 <samp>--with-gmp-include=<var>gmpinstalldir</var>/include</samp>. Likewise the 1591 <samp>--with-mpfr=<var>mpfrinstalldir</var></samp> option is shorthand for 1592 <samp>--with-mpfr-lib=<var>mpfrinstalldir</var>/lib</samp> and 1593 <samp>--with-mpfr-include=<var>mpfrinstalldir</var>/include</samp>, also the 1594 <samp>--with-mpc=<var>mpcinstalldir</var></samp> option is shorthand for 1595 <samp>--with-mpc-lib=<var>mpcinstalldir</var>/lib</samp> and 1596 <samp>--with-mpc-include=<var>mpcinstalldir</var>/include</samp>. If these 1597 shorthand assumptions are not correct, you can use the explicit 1598 include and lib options directly. You might also need to ensure the 1599 shared libraries can be found by the dynamic linker when building and 1600 using GCC, for example by setting the runtime shared library path 1601 variable (<code>LD_LIBRARY_PATH</code> on GNU/Linux and Solaris systems). 1602 </p> 1603 <p>These flags are applicable to the host platform only. When building 1604 a cross compiler, they will not be used to configure target libraries. 1605 </p> 1606 </dd> 1607 <dt><code>--with-isl=<var>pathname</var></code></dt> 1608 <dt><code>--with-isl-include=<var>pathname</var></code></dt> 1609 <dt><code>--with-isl-lib=<var>pathname</var></code></dt> 1610 <dd><p>If you do not have the isl library installed in a standard location and you 1611 want to build GCC, you can explicitly specify the directory where it is 1612 installed (‘<samp>--with-isl=<var>islinstalldir</var></samp>’). The 1613 <samp>--with-isl=<var>islinstalldir</var></samp> option is shorthand for 1614 <samp>--with-isl-lib=<var>islinstalldir</var>/lib</samp> and 1615 <samp>--with-isl-include=<var>islinstalldir</var>/include</samp>. If this 1616 shorthand assumption is not correct, you can use the explicit 1617 include and lib options directly. 1618 </p> 1619 <p>These flags are applicable to the host platform only. When building 1620 a cross compiler, they will not be used to configure target libraries. 1621 </p> 1622 </dd> 1623 <dt><code>--with-stage1-ldflags=<var>flags</var></code></dt> 1624 <dd><p>This option may be used to set linker flags to be used when linking 1625 stage 1 of GCC. These are also used when linking GCC if configured with 1626 <samp>--disable-bootstrap</samp>. If <samp>--with-stage1-libs</samp> is not set to a 1627 value, then the default is ‘<samp>-static-libstdc++ -static-libgcc</samp>’, if 1628 supported. 1629 </p> 1630 </dd> 1631 <dt><code>--with-stage1-libs=<var>libs</var></code></dt> 1632 <dd><p>This option may be used to set libraries to be used when linking stage 1 1633 of GCC. These are also used when linking GCC if configured with 1634 <samp>--disable-bootstrap</samp>. 1635 </p> 1636 </dd> 1637 <dt><code>--with-boot-ldflags=<var>flags</var></code></dt> 1638 <dd><p>This option may be used to set linker flags to be used when linking 1639 stage 2 and later when bootstrapping GCC. If –with-boot-libs 1640 is not is set to a value, then the default is 1641 ‘<samp>-static-libstdc++ -static-libgcc</samp>’. 1642 </p> 1643 </dd> 1644 <dt><code>--with-boot-libs=<var>libs</var></code></dt> 1645 <dd><p>This option may be used to set libraries to be used when linking stage 2 1646 and later when bootstrapping GCC. 1647 </p> 1648 </dd> 1649 <dt><code>--with-debug-prefix-map=<var>map</var></code></dt> 1650 <dd><p>Convert source directory names using <samp>-fdebug-prefix-map</samp> when 1651 building runtime libraries. ‘<samp><var>map</var></samp>’ is a space-separated 1652 list of maps of the form ‘<samp><var>old</var>=<var>new</var></samp>’. 1653 </p> 1654 </dd> 1655 <dt><code>--enable-linker-build-id</code></dt> 1656 <dd><p>Tells GCC to pass <samp>--build-id</samp> option to the linker for all final 1657 links (links performed without the <samp>-r</samp> or <samp>--relocatable</samp> 1658 option), if the linker supports it. If you specify 1659 <samp>--enable-linker-build-id</samp>, but your linker does not 1660 support <samp>--build-id</samp> option, a warning is issued and the 1661 <samp>--enable-linker-build-id</samp> option is ignored. The default is off. 1662 </p> 1663 </dd> 1664 <dt><code>--with-linker-hash-style=<var>choice</var></code></dt> 1665 <dd><p>Tells GCC to pass <samp>--hash-style=<var>choice</var></samp> option to the 1666 linker for all final links. <var>choice</var> can be one of 1667 ‘<samp>sysv</samp>’, ‘<samp>gnu</samp>’, and ‘<samp>both</samp>’ where ‘<samp>sysv</samp>’ is the default. 1668 </p> 1669 </dd> 1670 <dt><code>--enable-gnu-unique-object</code></dt> 1671 <dt><code>--disable-gnu-unique-object</code></dt> 1672 <dd><p>Tells GCC to use the gnu_unique_object relocation for C++ template 1673 static data members and inline function local statics. Enabled by 1674 default for a toolchain with an assembler that accepts it and 1675 GLIBC 2.11 or above, otherwise disabled. 1676 </p> 1677 </dd> 1678 <dt><code>--with-diagnostics-color=<var>choice</var></code></dt> 1679 <dd><p>Tells GCC to use <var>choice</var> as the default for <samp>-fdiagnostics-color=</samp> 1680 option (if not used explicitly on the command line). <var>choice</var> 1681 can be one of ‘<samp>never</samp>’, ‘<samp>auto</samp>’, ‘<samp>always</samp>’, and ‘<samp>auto-if-env</samp>’ 1682 where ‘<samp>auto</samp>’ is the default. ‘<samp>auto-if-env</samp>’ means that 1683 <samp>-fdiagnostics-color=auto</samp> will be the default if <code>GCC_COLORS</code> 1684 is present and non-empty in the environment, and 1685 <samp>-fdiagnostics-color=never</samp> otherwise. 1686 </p> 1687 </dd> 1688 <dt><code>--enable-lto</code></dt> 1689 <dt><code>--disable-lto</code></dt> 1690 <dd><p>Enable support for link-time optimization (LTO). This is enabled by 1691 default, and may be disabled using <samp>--disable-lto</samp>. 1692 </p> 1693 </dd> 1694 <dt><code>--enable-linker-plugin-configure-flags=FLAGS</code></dt> 1695 <dt><code>--enable-linker-plugin-flags=FLAGS</code></dt> 1696 <dd><p>By default, linker plugins (such as the LTO plugin) are built for the 1697 host system architecture. For the case that the linker has a 1698 different (but run-time compatible) architecture, these flags can be 1699 specified to build plugins that are compatible to the linker. For 1700 example, if you are building GCC for a 64-bit x86_64 1701 (‘<samp>x86_64-pc-linux-gnu</samp>’) host system, but have a 32-bit x86 1702 GNU/Linux (‘<samp>i686-pc-linux-gnu</samp>’) linker executable (which is 1703 executable on the former system), you can configure GCC as follows for 1704 getting compatible linker plugins: 1705 </p> 1706 <div class="smallexample"> 1707 <pre class="smallexample">% <var>srcdir</var>/configure \ 1708 --host=x86_64-pc-linux-gnu \ 1709 --enable-linker-plugin-configure-flags=--host=i686-pc-linux-gnu \ 1710 --enable-linker-plugin-flags='CC=gcc\ -m32\ -Wl,-rpath,[...]/i686-pc-linux-gnu/lib' 1711 </pre></div> 1712 1713 </dd> 1714 <dt><code>--with-plugin-ld=<var>pathname</var></code></dt> 1715 <dd><p>Enable an alternate linker to be used at link-time optimization (LTO) 1716 link time when <samp>-fuse-linker-plugin</samp> is enabled. 1717 This linker should have plugin support such as gold starting with 1718 version 2.20 or GNU ld starting with version 2.21. 1719 See <samp>-fuse-linker-plugin</samp> for details. 1720 </p> 1721 </dd> 1722 <dt><code>--enable-canonical-system-headers</code></dt> 1723 <dt><code>--disable-canonical-system-headers</code></dt> 1724 <dd><p>Enable system header path canonicalization for <samp>libcpp</samp>. This can 1725 produce shorter header file paths in diagnostics and dependency output 1726 files, but these changed header paths may conflict with some compilation 1727 environments. Enabled by default, and may be disabled using 1728 <samp>--disable-canonical-system-headers</samp>. 1729 </p> 1730 </dd> 1731 <dt><code>--with-glibc-version=<var>major</var>.<var>minor</var></code></dt> 1732 <dd><p>Tell GCC that when the GNU C Library (glibc) is used on the target it 1733 will be version <var>major</var>.<var>minor</var> or later. Normally this can 1734 be detected from the C library’s header files, but this option may be 1735 needed when bootstrapping a cross toolchain without the header files 1736 available for building the initial bootstrap compiler. 1737 </p> 1738 <p>If GCC is configured with some multilibs that use glibc and some that 1739 do not, this option applies only to the multilibs that use glibc. 1740 However, such configurations may not work well as not all the relevant 1741 configuration in GCC is on a per-multilib basis. 1742 </p> 1743 </dd> 1744 <dt><code>--enable-as-accelerator-for=<var>target</var></code></dt> 1745 <dd><p>Build as offload target compiler. Specify offload host triple by <var>target</var>. 1746 </p> 1747 </dd> 1748 <dt><code>--enable-offload-targets=<var>target1</var>[=<var>path1</var>],…,<var>targetN</var>[=<var>pathN</var>]</code></dt> 1749 <dd><p>Enable offloading to targets <var>target1</var>, …, <var>targetN</var>. 1750 Offload compilers are expected to be already installed. Default search 1751 path for them is <samp><var>exec-prefix</var></samp>, but it can be changed by 1752 specifying paths <var>path1</var>, …, <var>pathN</var>. 1753 </p> 1754 <div class="smallexample"> 1755 <pre class="smallexample">% <var>srcdir</var>/configure \ 1756 --enable-offload-targets=x86_64-intelmicemul-linux-gnu=/path/to/x86_64/compiler,nvptx-none,hsa 1757 </pre></div> 1758 1759 <p>If ‘<samp>hsa</samp>’ is specified as one of the targets, the compiler will be 1760 built with support for HSA GPU accelerators. Because the same 1761 compiler will emit the accelerator code, no path should be specified. 1762 </p> 1763 </dd> 1764 <dt><code>--with-hsa-runtime=<var>pathname</var></code></dt> 1765 <dt><code>--with-hsa-runtime-include=<var>pathname</var></code></dt> 1766 <dt><code>--with-hsa-runtime-lib=<var>pathname</var></code></dt> 1767 <dd> 1768 <p>If you configure GCC with HSA offloading but do not have the HSA 1769 run-time library installed in a standard location then you can 1770 explicitly specify the directory where they are installed. The 1771 <samp>--with-hsa-runtime=<var>hsainstalldir</var></samp> option is a 1772 shorthand for 1773 <samp>--with-hsa-runtime-lib=<var>hsainstalldir</var>/lib</samp> and 1774 <samp>--with-hsa-runtime-include=<var>hsainstalldir</var>/include</samp>. 1775 </p> 1776 </dd> 1777 <dt><code>--enable-cet</code></dt> 1778 <dt><code>--disable-cet</code></dt> 1779 <dd><p>Enable building target run-time libraries with control-flow 1780 instrumentation, see <samp>-fcf-protection</samp> option. When 1781 <code>--enable-cet</code> is specified target libraries are configured 1782 to add <samp>-fcf-protection</samp> and, if needed, other target 1783 specific options to a set of building options. 1784 </p> 1785 <p>The option is disabled by default. When <code>--enable-cet=auto</code> 1786 is used, it is enabled on Linux/x86 if target binutils 1787 supports <code>Intel CET</code> instructions and disabled otherwise. 1788 In this case the target libraries are configured to get additional 1789 <samp>-fcf-protection</samp> option. 1790 </p> 1791 </dd> 1792 <dt><code>--with-riscv-attribute=‘<samp>yes</samp>’, ‘<samp>no</samp>’ or ‘<samp>default</samp>’</code></dt> 1793 <dd><p>Generate RISC-V attribute by default, in order to record extra build 1794 information in object. 1795 </p> 1796 <p>The option is disabled by default. It is enabled on RISC-V/ELF (bare-metal) 1797 target if target binutils supported. 1798 </p></dd> 1799 </dl> 1800 1801 <a name="Cross-Compiler-Specific-Options"></a> 1802 <h4 class="subheading">Cross-Compiler-Specific Options</h4> 1803 <p>The following options only apply to building cross compilers. 1804 </p> 1805 <dl compact="compact"> 1806 <dt><code>--with-sysroot</code></dt> 1807 <dt><code>--with-sysroot=<var>dir</var></code></dt> 1808 <dd><p>Tells GCC to consider <var>dir</var> as the root of a tree that contains 1809 (a subset of) the root filesystem of the target operating system. 1810 Target system headers, libraries and run-time object files will be 1811 searched for in there. More specifically, this acts as if 1812 <samp>--sysroot=<var>dir</var></samp> was added to the default options of the built 1813 compiler. The specified directory is not copied into the 1814 install tree, unlike the options <samp>--with-headers</samp> and 1815 <samp>--with-libs</samp> that this option obsoletes. The default value, 1816 in case <samp>--with-sysroot</samp> is not given an argument, is 1817 <samp>${gcc_tooldir}/sys-root</samp>. If the specified directory is a 1818 subdirectory of <samp>${exec_prefix}</samp>, then it will be found relative to 1819 the GCC binaries if the installation tree is moved. 1820 </p> 1821 <p>This option affects the system root for the compiler used to build 1822 target libraries (which runs on the build system) and the compiler newly 1823 installed with <code>make install</code>; it does not affect the compiler which is 1824 used to build GCC itself. 1825 </p> 1826 <p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp> 1827 option then the compiler will search that directory within <var>dirname</var> for 1828 native system headers rather than the default <samp>/usr/include</samp>. 1829 </p> 1830 </dd> 1831 <dt><code>--with-build-sysroot</code></dt> 1832 <dt><code>--with-build-sysroot=<var>dir</var></code></dt> 1833 <dd><p>Tells GCC to consider <var>dir</var> as the system root (see 1834 <samp>--with-sysroot</samp>) while building target libraries, instead of 1835 the directory specified with <samp>--with-sysroot</samp>. This option is 1836 only useful when you are already using <samp>--with-sysroot</samp>. You 1837 can use <samp>--with-build-sysroot</samp> when you are configuring with 1838 <samp>--prefix</samp> set to a directory that is different from the one in 1839 which you are installing GCC and your target libraries. 1840 </p> 1841 <p>This option affects the system root for the compiler used to build 1842 target libraries (which runs on the build system); it does not affect 1843 the compiler which is used to build GCC itself. 1844 </p> 1845 <p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp> 1846 option then the compiler will search that directory within <var>dirname</var> for 1847 native system headers rather than the default <samp>/usr/include</samp>. 1848 </p> 1849 </dd> 1850 <dt><code>--with-headers</code></dt> 1851 <dt><code>--with-headers=<var>dir</var></code></dt> 1852 <dd><p>Deprecated in favor of <samp>--with-sysroot</samp>. 1853 Specifies that target headers are available when building a cross compiler. 1854 The <var>dir</var> argument specifies a directory which has the target include 1855 files. These include files will be copied into the <samp>gcc</samp> install 1856 directory. <em>This option with the <var>dir</var> argument is required</em> when 1857 building a cross compiler, if <samp><var>prefix</var>/<var>target</var>/sys-include</samp> 1858 doesn’t pre-exist. If <samp><var>prefix</var>/<var>target</var>/sys-include</samp> does 1859 pre-exist, the <var>dir</var> argument may be omitted. <code>fixincludes</code> 1860 will be run on these files to make them compatible with GCC. 1861 </p> 1862 </dd> 1863 <dt><code>--without-headers</code></dt> 1864 <dd><p>Tells GCC not use any target headers from a libc when building a cross 1865 compiler. When crossing to GNU/Linux, you need the headers so GCC 1866 can build the exception handling for libgcc. 1867 </p> 1868 </dd> 1869 <dt><code>--with-libs</code></dt> 1870 <dt><code>--with-libs="<var>dir1</var> <var>dir2</var> … <var>dirN</var>"</code></dt> 1871 <dd><p>Deprecated in favor of <samp>--with-sysroot</samp>. 1872 Specifies a list of directories which contain the target runtime 1873 libraries. These libraries will be copied into the <samp>gcc</samp> install 1874 directory. If the directory list is omitted, this option has no 1875 effect. 1876 </p> 1877 </dd> 1878 <dt><code>--with-newlib</code></dt> 1879 <dd><p>Specifies that ‘<samp>newlib</samp>’ is 1880 being used as the target C library. This causes <code>__eprintf</code> to be 1881 omitted from <samp>libgcc.a</samp> on the assumption that it will be provided by 1882 ‘<samp>newlib</samp>’. 1883 </p> 1884 </dd> 1885 <dt><code>--with-avrlibc</code></dt> 1886 <dd><p>Specifies that ‘<samp>AVR-Libc</samp>’ is 1887 being used as the target C library. This causes float support 1888 functions like <code>__addsf3</code> to be omitted from <samp>libgcc.a</samp> on 1889 the assumption that it will be provided by <samp>libm.a</samp>. For more 1890 technical details, cf. <a href="http://gcc.gnu.org/PR54461">PR54461</a>. 1891 This option is only supported for the AVR target. It is not supported for 1892 RTEMS configurations, which currently use newlib. The option is 1893 supported since version 4.7.2 and is the default in 4.8.0 and newer. 1894 </p> 1895 </dd> 1896 <dt><code>--with-nds32-lib=<var>library</var></code></dt> 1897 <dd><p>Specifies that <var>library</var> setting is used for building <samp>libgcc.a</samp>. 1898 Currently, the valid <var>library</var> is ‘<samp>newlib</samp>’ or ‘<samp>mculib</samp>’. 1899 This option is only supported for the NDS32 target. 1900 </p> 1901 </dd> 1902 <dt><code>--with-build-time-tools=<var>dir</var></code></dt> 1903 <dd><p>Specifies where to find the set of target tools (assembler, linker, etc.) 1904 that will be used while building GCC itself. This option can be useful 1905 if the directory layouts are different between the system you are building 1906 GCC on, and the system where you will deploy it. 1907 </p> 1908 <p>For example, on an ‘<samp>ia64-hp-hpux</samp>’ system, you may have the GNU 1909 assembler and linker in <samp>/usr/bin</samp>, and the native tools in a 1910 different path, and build a toolchain that expects to find the 1911 native tools in <samp>/usr/bin</samp>. 1912 </p> 1913 <p>When you use this option, you should ensure that <var>dir</var> includes 1914 <code>ar</code>, <code>as</code>, <code>ld</code>, <code>nm</code>, 1915 <code>ranlib</code> and <code>strip</code> if necessary, and possibly 1916 <code>objdump</code>. Otherwise, GCC may use an inconsistent set of 1917 tools. 1918 </p></dd> 1919 </dl> 1920 1921 <a name="Overriding-configure-test-results"></a> 1922 <h4 class="subsubheading">Overriding <code>configure</code> test results</h4> 1923 1924 <p>Sometimes, it might be necessary to override the result of some 1925 <code>configure</code> test, for example in order to ease porting to a new 1926 system or work around a bug in a test. The toplevel <code>configure</code> 1927 script provides three variables for this: 1928 </p> 1929 <dl compact="compact"> 1930 <dt><code>build_configargs</code></dt> 1931 <dd><a name="index-build_005fconfigargs"></a> 1932 <p>The contents of this variable is passed to all build <code>configure</code> 1933 scripts. 1934 </p> 1935 </dd> 1936 <dt><code>host_configargs</code></dt> 1937 <dd><a name="index-host_005fconfigargs"></a> 1938 <p>The contents of this variable is passed to all host <code>configure</code> 1939 scripts. 1940 </p> 1941 </dd> 1942 <dt><code>target_configargs</code></dt> 1943 <dd><a name="index-target_005fconfigargs"></a> 1944 <p>The contents of this variable is passed to all target <code>configure</code> 1945 scripts. 1946 </p> 1947 </dd> 1948 </dl> 1949 1950 <p>In order to avoid shell and <code>make</code> quoting issues for complex 1951 overrides, you can pass a setting for <code>CONFIG_SITE</code> and set 1952 variables in the site file. 1953 </p> 1954 <a name="Objective-C-Specific-Options"></a> 1955 <h4 class="subheading">Objective-C-Specific Options</h4> 1956 1957 <p>The following options apply to the build of the Objective-C runtime library. 1958 </p> 1959 <dl compact="compact"> 1960 <dt><code>--enable-objc-gc</code></dt> 1961 <dd><p>Specify that an additional variant of the GNU Objective-C runtime library 1962 is built, using an external build of the Boehm-Demers-Weiser garbage 1963 collector (<a href="http://www.hboehm.info/gc/">http://www.hboehm.info/gc/</a>). This library needs to be 1964 available for each multilib variant, unless configured with 1965 <samp>--enable-objc-gc=‘<samp>auto</samp>’</samp> in which case the build of the 1966 additional runtime library is skipped when not available and the build 1967 continues. 1968 </p> 1969 </dd> 1970 <dt><code>--with-target-bdw-gc=<var>list</var></code></dt> 1971 <dt><code>--with-target-bdw-gc-include=<var>list</var></code></dt> 1972 <dt><code>--with-target-bdw-gc-lib=<var>list</var></code></dt> 1973 <dd><p>Specify search directories for the garbage collector header files and 1974 libraries. <var>list</var> is a comma separated list of key value pairs of the 1975 form ‘<samp><var>multilibdir</var>=<var>path</var></samp>’, where the default multilib key 1976 is named as ‘<samp>.</samp>’ (dot), or is omitted (e.g. 1977 ‘<samp>--with-target-bdw-gc=/opt/bdw-gc,32=/opt-bdw-gc32</samp>’). 1978 </p> 1979 <p>The options <samp>--with-target-bdw-gc-include</samp> and 1980 <samp>--with-target-bdw-gc-lib</samp> must always be specified together 1981 for each multilib variant and they take precedence over 1982 <samp>--with-target-bdw-gc</samp>. If <samp>--with-target-bdw-gc-include</samp> 1983 is missing values for a multilib, then the value for the default 1984 multilib is used (e.g. ‘<samp>--with-target-bdw-gc-include=/opt/bdw-gc/include</samp>’ 1985 ‘<samp>--with-target-bdw-gc-lib=/opt/bdw-gc/lib64,32=/opt-bdw-gc/lib32</samp>’). 1986 If none of these options are specified, the library is assumed in 1987 default locations. 1988 </p></dd> 1989 </dl> 1990 1991 <a name="D-Specific-Options"></a> 1992 <h4 class="subheading">D-Specific Options</h4> 1993 1994 <p>The following options apply to the build of the D runtime library. 1995 </p> 1996 <dl compact="compact"> 1997 <dt><code>--with-target-system-zlib</code></dt> 1998 <dd><p>Use installed ‘<samp>zlib</samp>’ rather than that included with GCC. This needs 1999 to be available for each multilib variant, unless configured with 2000 <samp>--with-target-system-zlib=‘<samp>auto</samp>’</samp> in which case the GCC included 2001 ‘<samp>zlib</samp>’ is only used when the system installed library is not available. 2002 </p></dd> 2003 </dl> 2004 2005 <hr /> 2006 <p> 2007 <p><a href="./index.html">Return to the GCC Installation page</a> 2008 </p> 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 </body> 2021 </html> 2022
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