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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 <dt><code>--with-documentation-root-url=<var>url</var></code></dt> 163 <dd><p>Specify the URL root that contains GCC option documentation. The <var>url</var> 164 should end with a <code>/</code> character. 165 </p> 166 <p>The default value is <a href="https://gcc.gnu.org/onlinedocs/">https://gcc.gnu.org/onlinedocs/</a>. 167 </p> 168 </dd> 169 <dt><code>--with-changes-root-url=<var>url</var></code></dt> 170 <dd><p>Specify the URL root that contains information about changes in GCC 171 releases like <code>gcc-<var>version</var>/changes.html</code>. 172 The <var>url</var> should end with a <code>/</code> character. 173 </p> 174 <p>The default value is <a href="https://gcc.gnu.org/">https://gcc.gnu.org/</a>. 175 </p> 176 </dd> 177 </dl> 178 179 <a name="Host_002c-Build-and-Target-specification"></a> 180 <h3 class="heading">Host, Build and Target specification</h3> 181 182 <p>Specify the host, build and target machine configurations. You do this 183 when you run the <samp>configure</samp> script. 184 </p> 185 <p>The <em>build</em> machine is the system which you are using, the 186 <em>host</em> machine is the system where you want to run the resulting 187 compiler (normally the build machine), and the <em>target</em> machine is 188 the system for which you want the compiler to generate code. 189 </p> 190 <p>If you are building a compiler to produce code for the machine it runs 191 on (a native compiler), you normally do not need to specify any operands 192 to <samp>configure</samp>; it will try to guess the type of machine you are on 193 and use that as the build, host and target machines. So you don’t need 194 to specify a configuration when building a native compiler unless 195 <samp>configure</samp> cannot figure out what your configuration is or guesses 196 wrong. 197 </p> 198 <p>In those cases, specify the build machine’s <em>configuration name</em> 199 with the <samp>--host</samp> option; the host and target will default to be 200 the same as the host machine. 201 </p> 202 <p>Here is an example: 203 </p> 204 <div class="smallexample"> 205 <pre class="smallexample">./configure --host=x86_64-pc-linux-gnu 206 </pre></div> 207 208 <p>A configuration name may be canonical or it may be more or less 209 abbreviated (<samp>config.sub</samp> script produces canonical versions). 210 </p> 211 <p>A canonical configuration name has three parts, separated by dashes. 212 It looks like this: ‘<samp><var>cpu</var>-<var>company</var>-<var>system</var></samp>’. 213 </p> 214 <p>Here are the possible CPU types: 215 </p> 216 <blockquote> 217 <p>aarch64, aarch64_be, alpha, alpha64, amdgcn, arc, arceb, arm, armeb, avr, bfin, 218 bpf, cr16, cris, csky, epiphany, fido, fr30, frv, ft32, h8300, hppa, hppa2.0, 219 hppa64, i486, i686, ia64, iq2000, lm32, loongarch64, m32c, m32r, m32rle, m68k, 220 mcore, microblaze, microblazeel, mips, mips64, mips64el, mips64octeon, 221 mips64orion, mips64vr, mipsel, mipsisa32, mipsisa32r2, mipsisa64, mipsisa64r2, 222 mipsisa64r2el, mipsisa64sb1, mipsisa64sr71k, mipstx39, mmix, mn10300, moxie, 223 msp430, nds32be, nds32le, nios2, nvptx, or1k, pdp11, powerpc, powerpc64, 224 powerpc64le, powerpcle, pru, riscv32, riscv32be, riscv64, riscv64be, rl78, rx, 225 s390, s390x, sh, shle, sparc, sparc64, tic6x, tilegx, tilegxbe, tilepro, v850, 226 v850e, v850e1, vax, visium, x86_64, xstormy16, xtensa 227 </p></blockquote> 228 229 <p>Here is a list of system types: 230 </p> 231 <blockquote> 232 <p>aix<var>version</var>, amdhsa, aout, cygwin, darwin<var>version</var>, 233 eabi, eabialtivec, eabisim, eabisimaltivec, elf, elf32, 234 elfbare, elfoabi, freebsd<var>version</var>, gnu, hpux, hpux<var>version</var>, 235 kfreebsd-gnu, kopensolaris-gnu, linux-androideabi, linux-gnu, 236 linux-gnu_altivec, linux-musl, linux-uclibc, lynxos, mingw32, mingw32crt, 237 mmixware, msdosdjgpp, netbsd, netbsdelf<var>version</var>, nto-qnx, openbsd, 238 rtems, solaris<var>version</var>, symbianelf, tpf, uclinux, uclinux_eabi, vms, 239 vxworks, vxworksae, vxworksmils 240 </p></blockquote> 241 242 <a name="Options-specification"></a> 243 <h3 class="heading">Options specification</h3> 244 245 <p>Use <var>options</var> to override several configure time options for 246 GCC. A list of supported <var>options</var> follows; ‘<samp>configure 247 --help</samp>’ may list other options, but those not listed below may not 248 work and should not normally be used. 249 </p> 250 <p>Note that each <samp>--enable</samp> option has a corresponding 251 <samp>--disable</samp> option and that each <samp>--with</samp> option has a 252 corresponding <samp>--without</samp> option. 253 </p> 254 <dl compact="compact"> 255 <dt><code>--prefix=<var>dirname</var></code></dt> 256 <dd><p>Specify the toplevel installation 257 directory. This is the recommended way to install the tools into a directory 258 other than the default. The toplevel installation directory defaults to 259 <samp>/usr/local</samp>. 260 </p> 261 <p>We <strong>highly</strong> recommend against <var>dirname</var> being the same or a 262 subdirectory of <var>objdir</var> or vice versa. If specifying a directory 263 beneath a user’s home directory tree, some shells will not expand 264 <var>dirname</var> correctly if it contains the ‘<samp>~</samp>’ metacharacter; use 265 <code>$HOME</code> instead. 266 </p> 267 <p>The following standard <code>autoconf</code> options are supported. Normally you 268 should not need to use these options. 269 </p><dl compact="compact"> 270 <dt><code>--exec-prefix=<var>dirname</var></code></dt> 271 <dd><p>Specify the toplevel installation directory for architecture-dependent 272 files. The default is <samp><var>prefix</var></samp>. 273 </p> 274 </dd> 275 <dt><code>--bindir=<var>dirname</var></code></dt> 276 <dd><p>Specify the installation directory for the executables called by users 277 (such as <code>gcc</code> and <code>g++</code>). The default is 278 <samp><var>exec-prefix</var>/bin</samp>. 279 </p> 280 </dd> 281 <dt><code>--libdir=<var>dirname</var></code></dt> 282 <dd><p>Specify the installation directory for object code libraries and 283 internal data files of GCC. The default is <samp><var>exec-prefix</var>/lib</samp>. 284 </p> 285 </dd> 286 <dt><code>--libexecdir=<var>dirname</var></code></dt> 287 <dd><p>Specify the installation directory for internal executables of GCC. 288 The default is <samp><var>exec-prefix</var>/libexec</samp>. 289 </p> 290 </dd> 291 <dt><code>--with-slibdir=<var>dirname</var></code></dt> 292 <dd><p>Specify the installation directory for the shared libgcc library. The 293 default is <samp><var>libdir</var></samp>. 294 </p> 295 </dd> 296 <dt><code>--datarootdir=<var>dirname</var></code></dt> 297 <dd><p>Specify the root of the directory tree for read-only architecture-independent 298 data files referenced by GCC. The default is <samp><var>prefix</var>/share</samp>. 299 </p> 300 </dd> 301 <dt><code>--infodir=<var>dirname</var></code></dt> 302 <dd><p>Specify the installation directory for documentation in info format. 303 The default is <samp><var>datarootdir</var>/info</samp>. 304 </p> 305 </dd> 306 <dt><code>--datadir=<var>dirname</var></code></dt> 307 <dd><p>Specify the installation directory for some architecture-independent 308 data files referenced by GCC. The default is <samp><var>datarootdir</var></samp>. 309 </p> 310 </dd> 311 <dt><code>--docdir=<var>dirname</var></code></dt> 312 <dd><p>Specify the installation directory for documentation files (other 313 than Info) for GCC. The default is <samp><var>datarootdir</var>/doc</samp>. 314 </p> 315 </dd> 316 <dt><code>--htmldir=<var>dirname</var></code></dt> 317 <dd><p>Specify the installation directory for HTML documentation files. 318 The default is <samp><var>docdir</var></samp>. 319 </p> 320 </dd> 321 <dt><code>--pdfdir=<var>dirname</var></code></dt> 322 <dd><p>Specify the installation directory for PDF documentation files. 323 The default is <samp><var>docdir</var></samp>. 324 </p> 325 </dd> 326 <dt><code>--mandir=<var>dirname</var></code></dt> 327 <dd><p>Specify the installation directory for manual pages. The default is 328 <samp><var>datarootdir</var>/man</samp>. (Note that the manual pages are only extracts 329 from the full GCC manuals, which are provided in Texinfo format. The manpages 330 are derived by an automatic conversion process from parts of the full 331 manual.) 332 </p> 333 </dd> 334 <dt><code>--with-gxx-include-dir=<var>dirname</var></code></dt> 335 <dd><p>Specify 336 the installation directory for G++ header files. The default depends 337 on other configuration options, and differs between cross and native 338 configurations. 339 </p> 340 </dd> 341 <dt><code>--with-specs=<var>specs</var></code></dt> 342 <dd><p>Specify additional command line driver SPECS. 343 This can be useful if you need to turn on a non-standard feature by 344 default without modifying the compiler’s source code, for instance 345 <samp>--with-specs=%{!fcommon:%{!fno-common:-fno-common}}</samp>. 346 See “Spec Files” in the main manual 347 </p> 348 </dd> 349 </dl> 350 351 </dd> 352 <dt><code>--program-prefix=<var>prefix</var></code></dt> 353 <dd><p>GCC supports some transformations of the names of its programs when 354 installing them. This option prepends <var>prefix</var> to the names of 355 programs to install in <var>bindir</var> (see above). For example, specifying 356 <samp>--program-prefix=foo-</samp> would result in ‘<samp>gcc</samp>’ 357 being installed as <samp>/usr/local/bin/foo-gcc</samp>. 358 </p> 359 </dd> 360 <dt><code>--program-suffix=<var>suffix</var></code></dt> 361 <dd><p>Appends <var>suffix</var> to the names of programs to install in <var>bindir</var> 362 (see above). For example, specifying <samp>--program-suffix=-3.1</samp> 363 would result in ‘<samp>gcc</samp>’ being installed as 364 <samp>/usr/local/bin/gcc-3.1</samp>. 365 </p> 366 </dd> 367 <dt><code>--program-transform-name=<var>pattern</var></code></dt> 368 <dd><p>Applies the ‘<samp>sed</samp>’ script <var>pattern</var> to be applied to the names 369 of programs to install in <var>bindir</var> (see above). <var>pattern</var> has to 370 consist of one or more basic ‘<samp>sed</samp>’ editing commands, separated by 371 semicolons. For example, if you want the ‘<samp>gcc</samp>’ program name to be 372 transformed to the installed program <samp>/usr/local/bin/myowngcc</samp> and 373 the ‘<samp>g++</samp>’ program name to be transformed to 374 <samp>/usr/local/bin/gspecial++</samp> without changing other program names, 375 you could use the pattern 376 <samp>--program-transform-name='s/^gcc$/myowngcc/; s/^g++$/gspecial++/'</samp> 377 to achieve this effect. 378 </p> 379 <p>All three options can be combined and used together, resulting in more 380 complex conversion patterns. As a basic rule, <var>prefix</var> (and 381 <var>suffix</var>) are prepended (appended) before further transformations 382 can happen with a special transformation script <var>pattern</var>. 383 </p> 384 <p>As currently implemented, this option only takes effect for native 385 builds; cross compiler binaries’ names are not transformed even when a 386 transformation is explicitly asked for by one of these options. 387 </p> 388 <p>For native builds, some of the installed programs are also installed 389 with the target alias in front of their name, as in 390 ‘<samp>i686-pc-linux-gnu-gcc</samp>’. All of the above transformations happen 391 before the target alias is prepended to the name—so, specifying 392 <samp>--program-prefix=foo-</samp> and <samp>program-suffix=-3.1</samp>, the 393 resulting binary would be installed as 394 <samp>/usr/local/bin/i686-pc-linux-gnu-foo-gcc-3.1</samp>. 395 </p> 396 <p>As a last shortcoming, none of the installed Ada programs are 397 transformed yet, which will be fixed in some time. 398 </p> 399 </dd> 400 <dt><code>--with-local-prefix=<var>dirname</var></code></dt> 401 <dd><p>Specify the 402 installation directory for local include files. The default is 403 <samp>/usr/local</samp>. Specify this option if you want the compiler to 404 search directory <samp><var>dirname</var>/include</samp> for locally installed 405 header files <em>instead</em> of <samp>/usr/local/include</samp>. 406 </p> 407 <p>You should specify <samp>--with-local-prefix</samp> <strong>only</strong> if your 408 site has a different convention (not <samp>/usr/local</samp>) for where to put 409 site-specific files. 410 </p> 411 <p>The default value for <samp>--with-local-prefix</samp> is <samp>/usr/local</samp> 412 regardless of the value of <samp>--prefix</samp>. Specifying 413 <samp>--prefix</samp> has no effect on which directory GCC searches for 414 local header files. This may seem counterintuitive, but actually it is 415 logical. 416 </p> 417 <p>The purpose of <samp>--prefix</samp> is to specify where to <em>install 418 GCC</em>. The local header files in <samp>/usr/local/include</samp>—if you put 419 any in that directory—are not part of GCC. They are part of other 420 programs—perhaps many others. (GCC installs its own header files in 421 another directory which is based on the <samp>--prefix</samp> value.) 422 </p> 423 <p>Both the local-prefix include directory and the GCC-prefix include 424 directory are part of GCC’s “system include” directories. Although these 425 two directories are not fixed, they need to be searched in the proper 426 order for the correct processing of the include_next directive. The 427 local-prefix include directory is searched before the GCC-prefix 428 include directory. Another characteristic of system include directories 429 is that pedantic warnings are turned off for headers in these directories. 430 </p> 431 <p>Some autoconf macros add <samp>-I <var>directory</var></samp> options to the 432 compiler command line, to ensure that directories containing installed 433 packages’ headers are searched. When <var>directory</var> is one of GCC’s 434 system include directories, GCC will ignore the option so that system 435 directories continue to be processed in the correct order. This 436 may result in a search order different from what was specified but the 437 directory will still be searched. 438 </p> 439 <p>GCC automatically searches for ordinary libraries using 440 <code>GCC_EXEC_PREFIX</code>. Thus, when the same installation prefix is 441 used for both GCC and packages, GCC will automatically search for 442 both headers and libraries. This provides a configuration that is 443 easy to use. GCC behaves in a manner similar to that when it is 444 installed as a system compiler in <samp>/usr</samp>. 445 </p> 446 <p>Sites that need to install multiple versions of GCC may not want to 447 use the above simple configuration. It is possible to use the 448 <samp>--program-prefix</samp>, <samp>--program-suffix</samp> and 449 <samp>--program-transform-name</samp> options to install multiple versions 450 into a single directory, but it may be simpler to use different prefixes 451 and the <samp>--with-local-prefix</samp> option to specify the location of the 452 site-specific files for each version. It will then be necessary for 453 users to specify explicitly the location of local site libraries 454 (e.g., with <code>LIBRARY_PATH</code>). 455 </p> 456 <p>The same value can be used for both <samp>--with-local-prefix</samp> and 457 <samp>--prefix</samp> provided it is not <samp>/usr</samp>. This can be used 458 to avoid the default search of <samp>/usr/local/include</samp>. 459 </p> 460 <p><strong>Do not</strong> specify <samp>/usr</samp> as the <samp>--with-local-prefix</samp>! 461 The directory you use for <samp>--with-local-prefix</samp> <strong>must not</strong> 462 contain any of the system’s standard header files. If it did contain 463 them, certain programs would be miscompiled (including GNU Emacs, on 464 certain targets), because this would override and nullify the header 465 file corrections made by the <code>fixincludes</code> script. 466 </p> 467 <p>Indications are that people who use this option use it based on mistaken 468 ideas of what it is for. People use it as if it specified where to 469 install part of GCC. Perhaps they make this assumption because 470 installing GCC creates the directory. 471 </p> 472 </dd> 473 <dt><code>--with-gcc-major-version-only</code></dt> 474 <dd><p>Specifies that GCC should use only the major number rather than 475 <var>major</var>.<var>minor</var>.<var>patchlevel</var> in filesystem paths. 476 </p> 477 </dd> 478 <dt><code>--with-native-system-header-dir=<var>dirname</var></code></dt> 479 <dd><p>Specifies that <var>dirname</var> is the directory that contains native system 480 header files, rather than <samp>/usr/include</samp>. This option is most useful 481 if you are creating a compiler that should be isolated from the system 482 as much as possible. It is most commonly used with the 483 <samp>--with-sysroot</samp> option and will cause GCC to search 484 <var>dirname</var> inside the system root specified by that option. 485 </p> 486 </dd> 487 <dt><code>--enable-shared[=<var>package</var>[,…]]</code></dt> 488 <dd><p>Build shared versions of libraries, if shared libraries are supported on 489 the target platform. Unlike GCC 2.95.x and earlier, shared libraries 490 are enabled by default on all platforms that support shared libraries. 491 </p> 492 <p>If a list of packages is given as an argument, build shared libraries 493 only for the listed packages. For other packages, only static libraries 494 will be built. Package names currently recognized in the GCC tree are 495 ‘<samp>libgcc</samp>’ (also known as ‘<samp>gcc</samp>’), ‘<samp>libstdc++</samp>’ (not 496 ‘<samp>libstdc++-v3</samp>’), ‘<samp>libffi</samp>’, ‘<samp>zlib</samp>’, ‘<samp>boehm-gc</samp>’, 497 ‘<samp>ada</samp>’, ‘<samp>libada</samp>’, ‘<samp>libgo</samp>’, ‘<samp>libobjc</samp>’, and ‘<samp>libphobos</samp>’. 498 Note ‘<samp>libiberty</samp>’ does not support shared libraries at all. 499 </p> 500 <p>Use <samp>--disable-shared</samp> to build only static libraries. Note that 501 <samp>--disable-shared</samp> does not accept a list of package names as 502 argument, only <samp>--enable-shared</samp> does. 503 </p> 504 <p>Contrast with <samp>--enable-host-shared</samp>, which affects <em>host</em> 505 code. 506 </p> 507 </dd> 508 <dt><code>--enable-host-shared</code></dt> 509 <dd><p>Specify that the <em>host</em> code should be built into position-independent 510 machine code (with -fPIC), allowing it to be used within shared libraries, 511 but yielding a slightly slower compiler. 512 </p> 513 <p>This option is required when building the libgccjit.so library. 514 </p> 515 <p>Contrast with <samp>--enable-shared</samp>, which affects <em>target</em> 516 libraries. 517 </p> 518 </dd> 519 <dt><code><a name="with-gnu-as"></a>--with-gnu-as</code></dt> 520 <dd><p>Specify that the compiler should assume that the 521 assembler it finds is the GNU assembler. However, this does not modify 522 the rules to find an assembler and will result in confusion if the 523 assembler found is not actually the GNU assembler. (Confusion may also 524 result if the compiler finds the GNU assembler but has not been 525 configured with <samp>--with-gnu-as</samp>.) If you have more than one 526 assembler installed on your system, you may want to use this option in 527 connection with <samp>--with-as=<var>pathname</var></samp> or 528 <samp>--with-build-time-tools=<var>pathname</var></samp>. 529 </p> 530 <p>The following systems are the only ones where it makes a difference 531 whether you use the GNU assembler. On any other system, 532 <samp>--with-gnu-as</samp> has no effect. 533 </p> 534 <ul> 535 <li> ‘<samp>hppa1.0-<var>any</var>-<var>any</var></samp>’ 536 </li><li> ‘<samp>hppa1.1-<var>any</var>-<var>any</var></samp>’ 537 </li><li> ‘<samp>sparc-sun-solaris2.<var>any</var></samp>’ 538 </li><li> ‘<samp>sparc64-<var>any</var>-solaris2.<var>any</var></samp>’ 539 </li></ul> 540 541 </dd> 542 <dt><code><a name="with-as"></a>--with-as=<var>pathname</var></code></dt> 543 <dd><p>Specify that the compiler should use the assembler pointed to by 544 <var>pathname</var>, rather than the one found by the standard rules to find 545 an assembler, which are: 546 </p><ul> 547 <li> Unless GCC is being built with a cross compiler, check the 548 <samp><var>libexec</var>/gcc/<var>target</var>/<var>version</var></samp> directory. 549 <var>libexec</var> defaults to <samp><var>exec-prefix</var>/libexec</samp>; 550 <var>exec-prefix</var> defaults to <var>prefix</var>, which 551 defaults to <samp>/usr/local</samp> unless overridden by the 552 <samp>--prefix=<var>pathname</var></samp> switch described above. <var>target</var> 553 is the target system triple, such as ‘<samp>sparc-sun-solaris2.7</samp>’, and 554 <var>version</var> denotes the GCC version, such as 3.0. 555 556 </li><li> If the target system is the same that you are building on, check 557 operating system specific directories (e.g. <samp>/usr/ccs/bin</samp> on 558 Solaris 2). 559 560 </li><li> Check in the <code>PATH</code> for a tool whose name is prefixed by the 561 target system triple. 562 563 </li><li> Check in the <code>PATH</code> for a tool whose name is not prefixed by the 564 target system triple, if the host and target system triple are 565 the same (in other words, we use a host tool if it can be used for 566 the target as well). 567 </li></ul> 568 569 <p>You may want to use <samp>--with-as</samp> if no assembler 570 is installed in the directories listed above, or if you have multiple 571 assemblers installed and want to choose one that is not found by the 572 above rules. 573 </p> 574 </dd> 575 <dt><code><a name="with-gnu-ld"></a>--with-gnu-ld</code></dt> 576 <dd><p>Same as <a href="#with-gnu-as"><samp>--with-gnu-as</samp></a> 577 but for the linker. 578 </p> 579 </dd> 580 <dt><code>--with-ld=<var>pathname</var></code></dt> 581 <dd><p>Same as <a href="#with-as"><samp>--with-as</samp></a> 582 but for the linker. 583 </p> 584 </dd> 585 <dt><code>--with-dsymutil=<var>pathname</var></code></dt> 586 <dd><p>Same as <a href="#with-as"><samp>--with-as</samp></a> 587 but for the debug linker (only used on Darwin platforms so far). 588 </p> 589 </dd> 590 <dt><code>--with-tls=<var>dialect</var></code></dt> 591 <dd><p>Specify the default TLS dialect, for systems were there is a choice. 592 For ARM targets, possible values for <var>dialect</var> are <code>gnu</code> or 593 <code>gnu2</code>, which select between the original GNU dialect and the GNU TLS 594 descriptor-based dialect. 595 </p> 596 </dd> 597 <dt><code>--enable-multiarch</code></dt> 598 <dd><p>Specify whether to enable or disable multiarch support. The default is 599 to check for glibc start files in a multiarch location, and enable it 600 if the files are found. The auto detection is enabled for native builds, 601 and for cross builds configured with <samp>--with-sysroot</samp>, and without 602 <samp>--with-native-system-header-dir</samp>. 603 More documentation about multiarch can be found at 604 <a href="https://wiki.debian.org/Multiarch">https://wiki.debian.org/Multiarch</a>. 605 </p> 606 </dd> 607 <dt><code>--enable-sjlj-exceptions</code></dt> 608 <dd><p>Force use of the <code>setjmp</code>/<code>longjmp</code>-based scheme for exceptions. 609 ‘<samp>configure</samp>’ ordinarily picks the correct value based on the platform. 610 Only use this option if you are sure you need a different setting. 611 </p> 612 </dd> 613 <dt><code>--enable-vtable-verify</code></dt> 614 <dd><p>Specify whether to enable or disable the vtable verification feature. 615 Enabling this feature causes libstdc++ to be built with its virtual calls 616 in verifiable mode. This means that, when linked with libvtv, every 617 virtual call in libstdc++ will verify the vtable pointer through which the 618 call will be made before actually making the call. If not linked with libvtv, 619 the verifier will call stub functions (in libstdc++ itself) and do nothing. 620 If vtable verification is disabled, then libstdc++ is not built with its 621 virtual calls in verifiable mode at all. However the libvtv library will 622 still be built (see <samp>--disable-libvtv</samp> to turn off building libvtv). 623 <samp>--disable-vtable-verify</samp> is the default. 624 </p> 625 </dd> 626 <dt><code>--disable-gcov</code></dt> 627 <dd><p>Specify that the run-time library used for coverage analysis 628 and associated host tools should not be built. 629 </p> 630 </dd> 631 <dt><code>--disable-multilib</code></dt> 632 <dd><p>Specify that multiple target 633 libraries to support different target variants, calling 634 conventions, etc. should not be built. The default is to build a 635 predefined set of them. 636 </p> 637 <p>Some targets provide finer-grained control over which multilibs are built 638 (e.g., <samp>--disable-softfloat</samp>): 639 </p><dl compact="compact"> 640 <dt><code>arm-*-*</code></dt> 641 <dd><p>fpu, 26bit, underscore, interwork, biendian, nofmult. 642 </p> 643 </dd> 644 <dt><code>m68*-*-*</code></dt> 645 <dd><p>softfloat, m68881, m68000, m68020. 646 </p> 647 </dd> 648 <dt><code>mips*-*-*</code></dt> 649 <dd><p>single-float, biendian, softfloat. 650 </p> 651 </dd> 652 <dt><code>msp430-*-*</code></dt> 653 <dd><p>no-exceptions 654 </p> 655 </dd> 656 <dt><code>powerpc*-*-*, rs6000*-*-*</code></dt> 657 <dd><p>aix64, pthread, softfloat, powercpu, powerpccpu, powerpcos, biendian, 658 sysv, aix. 659 </p> 660 </dd> 661 </dl> 662 663 </dd> 664 <dt><code>--with-multilib-list=<var>list</var></code></dt> 665 <dt><code>--without-multilib-list</code></dt> 666 <dd><p>Specify what multilibs to build. <var>list</var> is a comma separated list of 667 values, possibly consisting of a single value. Currently only implemented 668 for aarch64*-*-*, arm*-*-*, loongarch64-*-*, riscv*-*-*, sh*-*-* and 669 x86-64-*-linux*. The accepted values and meaning for each target is given 670 below. 671 </p> 672 <dl compact="compact"> 673 <dt><code>aarch64*-*-*</code></dt> 674 <dd><p><var>list</var> is a comma separated list of <code>ilp32</code>, and <code>lp64</code> 675 to enable ILP32 and LP64 run-time libraries, respectively. If 676 <var>list</var> is empty, then there will be no multilibs and only the 677 default run-time library will be built. If <var>list</var> is 678 <code>default</code> or –with-multilib-list= is not specified, then the 679 default set of libraries is selected based on the value of 680 <samp>--target</samp>. 681 </p> 682 </dd> 683 <dt><code>arm*-*-*</code></dt> 684 <dd><p><var>list</var> is a comma separated list of <code>aprofile</code> and 685 <code>rmprofile</code> to build multilibs for A or R and M architecture 686 profiles respectively. Note that, due to some limitation of the current 687 multilib framework, using the combined <code>aprofile,rmprofile</code> 688 multilibs selects in some cases a less optimal multilib than when using 689 the multilib profile for the architecture targetted. The special value 690 <code>default</code> is also accepted and is equivalent to omitting the 691 option, i.e., only the default run-time library will be enabled. 692 </p> 693 <p><var>list</var> may instead contain <code>@name</code>, to use the multilib 694 configuration Makefile fragment <samp>name</samp> in <samp>gcc/config/arm</samp> in 695 the source tree (it is part of the corresponding sources, after all). 696 It is recommended, but not required, that files used for this purpose to 697 be named starting with <samp>t-ml-</samp>, to make their intended purpose 698 self-evident, in line with GCC conventions. Such files enable custom, 699 user-chosen multilib lists to be configured. Whether multiple such 700 files can be used together depends on the contents of the supplied 701 files. See <samp>gcc/config/arm/t-multilib</samp> and its supplementary 702 <samp>gcc/config/arm/t-*profile</samp> files for an example of what such 703 Makefile fragments might look like for this version of GCC. The macros 704 expected to be defined in these fragments are not stable across GCC 705 releases, so make sure they define the <code>MULTILIB</code>-related macros 706 expected by the version of GCC you are building. 707 See “Target Makefile Fragments” in the internals manual. 708 </p> 709 <p>The table below gives the combination of ISAs, architectures, FPUs and 710 floating-point ABIs for which multilibs are built for each predefined 711 profile. The union of these options is considered when specifying both 712 <code>aprofile</code> and <code>rmprofile</code>. 713 </p> 714 <table> 715 <tr><td width="15%">Option</td><td width="28%">aprofile</td><td width="30%">rmprofile</td></tr> 716 <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> 717 <tr><td width="15%">Architectures<br><br><br><br><br><br></td><td width="28%">default architecture<br> 718 <code>-march=armv7-a</code><br> 719 <code>-march=armv7ve</code><br> 720 <code>-march=armv8-a</code><br><br><br></td><td width="30%">default architecture<br> 721 <code>-march=armv6s-m</code><br> 722 <code>-march=armv7-m</code><br> 723 <code>-march=armv7e-m</code><br> 724 <code>-march=armv8-m.base</code><br> 725 <code>-march=armv8-m.main</code><br> 726 <code>-march=armv7</code></td></tr> 727 <tr><td width="15%">FPUs<br><br><br><br><br></td><td width="28%">none<br> 728 <code>-mfpu=vfpv3-d16</code><br> 729 <code>-mfpu=neon</code><br> 730 <code>-mfpu=vfpv4-d16</code><br> 731 <code>-mfpu=neon-vfpv4</code><br> 732 <code>-mfpu=neon-fp-armv8</code></td><td width="30%">none<br> 733 <code>-mfpu=vfpv3-d16</code><br> 734 <code>-mfpu=fpv4-sp-d16</code><br> 735 <code>-mfpu=fpv5-sp-d16</code><br> 736 <code>-mfpu=fpv5-d16</code><br></td></tr> 737 <tr><td width="15%">floating-point ABIs<br><br></td><td width="28%"><code>-mfloat-abi=soft</code><br> 738 <code>-mfloat-abi=softfp</code><br> 739 <code>-mfloat-abi=hard</code></td><td width="30%"><code>-mfloat-abi=soft</code><br> 740 <code>-mfloat-abi=softfp</code><br> 741 <code>-mfloat-abi=hard</code></td></tr> 742 </table> 743 744 </dd> 745 <dt><code>loongarch*-*-*</code></dt> 746 <dd><p><var>list</var> is a comma-separated list of the following ABI identifiers: 747 <code>lp64d[/base]</code> <code>lp64f[/base]</code> <code>lp64d[/base]</code>, where the 748 <code>/base</code> suffix may be omitted, to enable their respective run-time 749 libraries. If <var>list</var> is empty or <code>default</code>, 750 or if <samp>--with-multilib-list</samp> is not specified, then the default ABI 751 as specified by <samp>--with-abi</samp> or implied by <samp>--target</samp> is selected. 752 </p> 753 </dd> 754 <dt><code>riscv*-*-*</code></dt> 755 <dd><p><var>list</var> is a single ABI name. The target architecture must be either 756 <code>rv32gc</code> or <code>rv64gc</code>. This will build a single multilib for the 757 specified architecture and ABI pair. If <code>--with-multilib-list</code> is not 758 given, then a default set of multilibs is selected based on the value of 759 <samp>--target</samp>. This is usually a large set of multilibs. 760 </p> 761 </dd> 762 <dt><code>sh*-*-*</code></dt> 763 <dd><p><var>list</var> is a comma separated list of CPU names. These must be of the 764 form <code>sh*</code> or <code>m*</code> (in which case they match the compiler option 765 for that processor). The list should not contain any endian options - 766 these are handled by <samp>--with-endian</samp>. 767 </p> 768 <p>If <var>list</var> is empty, then there will be no multilibs for extra 769 processors. The multilib for the secondary endian remains enabled. 770 </p> 771 <p>As a special case, if an entry in the list starts with a <code>!</code> 772 (exclamation point), then it is added to the list of excluded multilibs. 773 Entries of this sort should be compatible with ‘<samp>MULTILIB_EXCLUDES</samp>’ 774 (once the leading <code>!</code> has been stripped). 775 </p> 776 <p>If <samp>--with-multilib-list</samp> is not given, then a default set of 777 multilibs is selected based on the value of <samp>--target</samp>. This is 778 usually the complete set of libraries, but some targets imply a more 779 specialized subset. 780 </p> 781 <p>Example 1: to configure a compiler for SH4A only, but supporting both 782 endians, with little endian being the default: 783 </p><div class="smallexample"> 784 <pre class="smallexample">--with-cpu=sh4a --with-endian=little,big --with-multilib-list= 785 </pre></div> 786 787 <p>Example 2: to configure a compiler for both SH4A and SH4AL-DSP, but with 788 only little endian SH4AL: 789 </p><div class="smallexample"> 790 <pre class="smallexample">--with-cpu=sh4a --with-endian=little,big \ 791 --with-multilib-list=sh4al,!mb/m4al 792 </pre></div> 793 794 </dd> 795 <dt><code>x86-64-*-linux*</code></dt> 796 <dd><p><var>list</var> is a comma separated list of <code>m32</code>, <code>m64</code> and 797 <code>mx32</code> to enable 32-bit, 64-bit and x32 run-time libraries, 798 respectively. If <var>list</var> is empty, then there will be no multilibs 799 and only the default run-time library will be enabled. 800 </p> 801 <p>If <samp>--with-multilib-list</samp> is not given, then only 32-bit and 802 64-bit run-time libraries will be enabled. 803 </p></dd> 804 </dl> 805 806 </dd> 807 <dt><code>--with-multilib-generator=<var>config</var></code></dt> 808 <dd><p>Specify what multilibs to build. <var>config</var> is a semicolon separated list of 809 values, possibly consisting of a single value. Currently only implemented 810 for riscv*-*-elf*. The accepted values and meanings are given below. 811 </p> 812 813 <p>Every config is constructed with four components: architecture string, ABI, 814 reuse rule with architecture string and reuse rule with sub-extension. 815 </p> 816 <p>Example 1: Add multi-lib suppport for rv32i with ilp32. 817 </p><div class="smallexample"> 818 <pre class="smallexample">rv32i-ilp32-- 819 </pre></div> 820 821 <p>Example 2: Add multi-lib suppport for rv32i with ilp32 and rv32imafd with ilp32. 822 </p><div class="smallexample"> 823 <pre class="smallexample">rv32i-ilp32--;rv32imafd-ilp32-- 824 </pre></div> 825 826 <p>Example 3: Add multi-lib suppport for rv32i with ilp32; rv32im with ilp32 and 827 rv32ic with ilp32 will reuse this multi-lib set. 828 </p><div class="smallexample"> 829 <pre class="smallexample">rv32i-ilp32-rv32im-c 830 </pre></div> 831 832 <p>Example 4: Add multi-lib suppport for rv64ima with lp64; rv64imaf with lp64, 833 rv64imac with lp64 and rv64imafc with lp64 will reuse this multi-lib set. 834 </p><div class="smallexample"> 835 <pre class="smallexample">rv64ima-lp64--f,c,fc 836 </pre></div> 837 838 <p><samp>--with-multilib-generator</samp> have an optional configuration argument 839 <samp>--cmodel=val</samp> for code model, this option will expand with other 840 config options, <var>val</var> is a comma separated list of possible code model, 841 currently we support medlow and medany. 842 </p> 843 <p>Example 5: Add multi-lib suppport for rv64ima with lp64; rv64ima with lp64 and 844 medlow code model 845 </p><div class="smallexample"> 846 <pre class="smallexample">rv64ima-lp64--;--cmodel=medlow 847 </pre></div> 848 849 <p>Example 6: Add multi-lib suppport for rv64ima with lp64; rv64ima with lp64 and 850 medlow code model; rv64ima with lp64 and medany code model 851 </p><div class="smallexample"> 852 <pre class="smallexample">rv64ima-lp64--;--cmodel=medlow,medany 853 </pre></div> 854 855 </dd> 856 <dt><code>--with-endian=<var>endians</var></code></dt> 857 <dd><p>Specify what endians to use. 858 Currently only implemented for sh*-*-*. 859 </p> 860 <p><var>endians</var> may be one of the following: 861 </p><dl compact="compact"> 862 <dt><code>big</code></dt> 863 <dd><p>Use big endian exclusively. 864 </p></dd> 865 <dt><code>little</code></dt> 866 <dd><p>Use little endian exclusively. 867 </p></dd> 868 <dt><code>big,little</code></dt> 869 <dd><p>Use big endian by default. Provide a multilib for little endian. 870 </p></dd> 871 <dt><code>little,big</code></dt> 872 <dd><p>Use little endian by default. Provide a multilib for big endian. 873 </p></dd> 874 </dl> 875 876 </dd> 877 <dt><code>--enable-threads</code></dt> 878 <dd><p>Specify that the target 879 supports threads. This affects the Objective-C compiler and runtime 880 library, and exception handling for other languages like C++. 881 On some systems, this is the default. 882 </p> 883 <p>In general, the best (and, in many cases, the only known) threading 884 model available will be configured for use. Beware that on some 885 systems, GCC has not been taught what threading models are generally 886 available for the system. In this case, <samp>--enable-threads</samp> is an 887 alias for <samp>--enable-threads=single</samp>. 888 </p> 889 </dd> 890 <dt><code>--disable-threads</code></dt> 891 <dd><p>Specify that threading support should be disabled for the system. 892 This is an alias for <samp>--enable-threads=single</samp>. 893 </p> 894 </dd> 895 <dt><code>--enable-threads=<var>lib</var></code></dt> 896 <dd><p>Specify that 897 <var>lib</var> is the thread support library. This affects the Objective-C 898 compiler and runtime library, and exception handling for other languages 899 like C++. The possibilities for <var>lib</var> are: 900 </p> 901 <dl compact="compact"> 902 <dt><code>aix</code></dt> 903 <dd><p>AIX thread support. 904 </p></dd> 905 <dt><code>dce</code></dt> 906 <dd><p>DCE thread support. 907 </p></dd> 908 <dt><code>lynx</code></dt> 909 <dd><p>LynxOS thread support. 910 </p></dd> 911 <dt><code>mipssde</code></dt> 912 <dd><p>MIPS SDE thread support. 913 </p></dd> 914 <dt><code>no</code></dt> 915 <dd><p>This is an alias for ‘<samp>single</samp>’. 916 </p></dd> 917 <dt><code>posix</code></dt> 918 <dd><p>Generic POSIX/Unix98 thread support. 919 </p></dd> 920 <dt><code>rtems</code></dt> 921 <dd><p>RTEMS thread support. 922 </p></dd> 923 <dt><code>single</code></dt> 924 <dd><p>Disable thread support, should work for all platforms. 925 </p></dd> 926 <dt><code>tpf</code></dt> 927 <dd><p>TPF thread support. 928 </p></dd> 929 <dt><code>vxworks</code></dt> 930 <dd><p>VxWorks thread support. 931 </p></dd> 932 <dt><code>win32</code></dt> 933 <dd><p>Microsoft Win32 API thread support. 934 </p></dd> 935 </dl> 936 937 </dd> 938 <dt><code>--enable-tls</code></dt> 939 <dd><p>Specify that the target supports TLS (Thread Local Storage). Usually 940 configure can correctly determine if TLS is supported. In cases where 941 it guesses incorrectly, TLS can be explicitly enabled or disabled with 942 <samp>--enable-tls</samp> or <samp>--disable-tls</samp>. This can happen if 943 the assembler supports TLS but the C library does not, or if the 944 assumptions made by the configure test are incorrect. 945 </p> 946 </dd> 947 <dt><code>--disable-tls</code></dt> 948 <dd><p>Specify that the target does not support TLS. 949 This is an alias for <samp>--enable-tls=no</samp>. 950 </p> 951 </dd> 952 <dt><code>--disable-tm-clone-registry</code></dt> 953 <dd><p>Disable TM clone registry in libgcc. It is enabled in libgcc by default. 954 This option helps to reduce code size for embedded targets which do 955 not use transactional memory. 956 </p> 957 </dd> 958 <dt><code>--with-cpu=<var>cpu</var></code></dt> 959 <dt><code>--with-cpu-32=<var>cpu</var></code></dt> 960 <dt><code>--with-cpu-64=<var>cpu</var></code></dt> 961 <dd><p>Specify which cpu variant the compiler should generate code for by default. 962 <var>cpu</var> will be used as the default value of the <samp>-mcpu=</samp> switch. 963 This option is only supported on some targets, including ARC, ARM, i386, M68k, 964 PowerPC, and SPARC. It is mandatory for ARC. The <samp>--with-cpu-32</samp> and 965 <samp>--with-cpu-64</samp> options specify separate default CPUs for 966 32-bit and 64-bit modes; these options are only supported for aarch64, i386, 967 x86-64, PowerPC, and SPARC. 968 </p> 969 </dd> 970 <dt><code>--with-schedule=<var>cpu</var></code></dt> 971 <dt><code>--with-arch=<var>cpu</var></code></dt> 972 <dt><code>--with-arch-32=<var>cpu</var></code></dt> 973 <dt><code>--with-arch-64=<var>cpu</var></code></dt> 974 <dt><code>--with-tune=<var>cpu</var></code></dt> 975 <dt><code>--with-tune-32=<var>cpu</var></code></dt> 976 <dt><code>--with-tune-64=<var>cpu</var></code></dt> 977 <dt><code>--with-abi=<var>abi</var></code></dt> 978 <dt><code>--with-fpu=<var>type</var></code></dt> 979 <dt><code>--with-float=<var>type</var></code></dt> 980 <dd><p>These configure options provide default values for the <samp>-mschedule=</samp>, 981 <samp>-march=</samp>, <samp>-mtune=</samp>, <samp>-mabi=</samp>, and <samp>-mfpu=</samp> 982 options and for <samp>-mhard-float</samp> or <samp>-msoft-float</samp>. As with 983 <samp>--with-cpu</samp>, which switches will be accepted and acceptable values 984 of the arguments depend on the target. 985 </p> 986 </dd> 987 <dt><code>--with-mode=<var>mode</var></code></dt> 988 <dd><p>Specify if the compiler should default to <samp>-marm</samp> or <samp>-mthumb</samp>. 989 This option is only supported on ARM targets. 990 </p> 991 </dd> 992 <dt><code>--with-stack-offset=<var>num</var></code></dt> 993 <dd><p>This option sets the default for the -mstack-offset=<var>num</var> option, 994 and will thus generally also control the setting of this option for 995 libraries. This option is only supported on Epiphany targets. 996 </p> 997 </dd> 998 <dt><code>--with-fpmath=<var>isa</var></code></dt> 999 <dd><p>This options sets <samp>-mfpmath=sse</samp> by default and specifies the default 1000 ISA for floating-point arithmetics. You can select either ‘<samp>sse</samp>’ which 1001 enables <samp>-msse2</samp> or ‘<samp>avx</samp>’ which enables <samp>-mavx</samp> by default. 1002 This option is only supported on i386 and x86-64 targets. 1003 </p> 1004 </dd> 1005 <dt><code>--with-fp-32=<var>mode</var></code></dt> 1006 <dd><p>On MIPS targets, set the default value for the <samp>-mfp</samp> option when using 1007 the o32 ABI. The possibilities for <var>mode</var> are: 1008 </p><dl compact="compact"> 1009 <dt><code>32</code></dt> 1010 <dd><p>Use the o32 FP32 ABI extension, as with the <samp>-mfp32</samp> command-line 1011 option. 1012 </p></dd> 1013 <dt><code>xx</code></dt> 1014 <dd><p>Use the o32 FPXX ABI extension, as with the <samp>-mfpxx</samp> command-line 1015 option. 1016 </p></dd> 1017 <dt><code>64</code></dt> 1018 <dd><p>Use the o32 FP64 ABI extension, as with the <samp>-mfp64</samp> command-line 1019 option. 1020 </p></dd> 1021 </dl> 1022 <p>In the absence of this configuration option the default is to use the o32 1023 FP32 ABI extension. 1024 </p> 1025 </dd> 1026 <dt><code>--with-odd-spreg-32</code></dt> 1027 <dd><p>On MIPS targets, set the <samp>-modd-spreg</samp> option by default when using 1028 the o32 ABI. 1029 </p> 1030 </dd> 1031 <dt><code>--without-odd-spreg-32</code></dt> 1032 <dd><p>On MIPS targets, set the <samp>-mno-odd-spreg</samp> option by default when using 1033 the o32 ABI. This is normally used in conjunction with 1034 <samp>--with-fp-32=64</samp> in order to target the o32 FP64A ABI extension. 1035 </p> 1036 </dd> 1037 <dt><code>--with-nan=<var>encoding</var></code></dt> 1038 <dd><p>On MIPS targets, set the default encoding convention to use for the 1039 special not-a-number (NaN) IEEE 754 floating-point data. The 1040 possibilities for <var>encoding</var> are: 1041 </p><dl compact="compact"> 1042 <dt><code>legacy</code></dt> 1043 <dd><p>Use the legacy encoding, as with the <samp>-mnan=legacy</samp> command-line 1044 option. 1045 </p></dd> 1046 <dt><code>2008</code></dt> 1047 <dd><p>Use the 754-2008 encoding, as with the <samp>-mnan=2008</samp> command-line 1048 option. 1049 </p></dd> 1050 </dl> 1051 <p>To use this configuration option you must have an assembler version 1052 installed that supports the <samp>-mnan=</samp> command-line option too. 1053 In the absence of this configuration option the default convention is 1054 the legacy encoding, as when neither of the <samp>-mnan=2008</samp> and 1055 <samp>-mnan=legacy</samp> command-line options has been used. 1056 </p> 1057 </dd> 1058 <dt><code>--with-divide=<var>type</var></code></dt> 1059 <dd><p>Specify how the compiler should generate code for checking for 1060 division by zero. This option is only supported on the MIPS target. 1061 The possibilities for <var>type</var> are: 1062 </p><dl compact="compact"> 1063 <dt><code>traps</code></dt> 1064 <dd><p>Division by zero checks use conditional traps (this is the default on 1065 systems that support conditional traps). 1066 </p></dd> 1067 <dt><code>breaks</code></dt> 1068 <dd><p>Division by zero checks use the break instruction. 1069 </p></dd> 1070 </dl> 1071 1072 1073 </dd> 1074 <dt><code>--with-llsc</code></dt> 1075 <dd><p>On MIPS targets, make <samp>-mllsc</samp> the default when no 1076 <samp>-mno-llsc</samp> option is passed. This is the default for 1077 Linux-based targets, as the kernel will emulate them if the ISA does 1078 not provide them. 1079 </p> 1080 </dd> 1081 <dt><code>--without-llsc</code></dt> 1082 <dd><p>On MIPS targets, make <samp>-mno-llsc</samp> the default when no 1083 <samp>-mllsc</samp> option is passed. 1084 </p> 1085 </dd> 1086 <dt><code>--with-synci</code></dt> 1087 <dd><p>On MIPS targets, make <samp>-msynci</samp> the default when no 1088 <samp>-mno-synci</samp> option is passed. 1089 </p> 1090 </dd> 1091 <dt><code>--without-synci</code></dt> 1092 <dd><p>On MIPS targets, make <samp>-mno-synci</samp> the default when no 1093 <samp>-msynci</samp> option is passed. This is the default. 1094 </p> 1095 </dd> 1096 <dt><code>--with-lxc1-sxc1</code></dt> 1097 <dd><p>On MIPS targets, make <samp>-mlxc1-sxc1</samp> the default when no 1098 <samp>-mno-lxc1-sxc1</samp> option is passed. This is the default. 1099 </p> 1100 </dd> 1101 <dt><code>--without-lxc1-sxc1</code></dt> 1102 <dd><p>On MIPS targets, make <samp>-mno-lxc1-sxc1</samp> the default when no 1103 <samp>-mlxc1-sxc1</samp> option is passed. The indexed load/store 1104 instructions are not directly a problem but can lead to unexpected 1105 behaviour when deployed in an application intended for a 32-bit address 1106 space but run on a 64-bit processor. The issue is seen because all 1107 known MIPS 64-bit Linux kernels execute o32 and n32 applications 1108 with 64-bit addressing enabled which affects the overflow behaviour 1109 of the indexed addressing mode. GCC will assume that ordinary 1110 32-bit arithmetic overflow behaviour is the same whether performed 1111 as an <code>addu</code> instruction or as part of the address calculation 1112 in <code>lwxc1</code> type instructions. This assumption holds true in a 1113 pure 32-bit environment and can hold true in a 64-bit environment if 1114 the address space is accurately set to be 32-bit for o32 and n32. 1115 </p> 1116 </dd> 1117 <dt><code>--with-madd4</code></dt> 1118 <dd><p>On MIPS targets, make <samp>-mmadd4</samp> the default when no 1119 <samp>-mno-madd4</samp> option is passed. This is the default. 1120 </p> 1121 </dd> 1122 <dt><code>--without-madd4</code></dt> 1123 <dd><p>On MIPS targets, make <samp>-mno-madd4</samp> the default when no 1124 <samp>-mmadd4</samp> option is passed. The <code>madd4</code> instruction 1125 family can be problematic when targeting a combination of cores that 1126 implement these instructions differently. There are two known cores 1127 that implement these as fused operations instead of unfused (where 1128 unfused is normally expected). Disabling these instructions is the 1129 only way to ensure compatible code is generated; this will incur 1130 a performance penalty. 1131 </p> 1132 </dd> 1133 <dt><code>--with-mips-plt</code></dt> 1134 <dd><p>On MIPS targets, make use of copy relocations and PLTs. 1135 These features are extensions to the traditional 1136 SVR4-based MIPS ABIs and require support from GNU binutils 1137 and the runtime C library. 1138 </p> 1139 </dd> 1140 <dt><code>--with-stack-clash-protection-guard-size=<var>size</var></code></dt> 1141 <dd><p>On certain targets this option sets the default stack clash protection guard 1142 size as a power of two in bytes. On AArch64 <var>size</var> is required to be either 1143 12 (4KB) or 16 (64KB). 1144 </p> 1145 </dd> 1146 <dt><code>--with-isa-spec=<var>ISA-spec-string</var></code></dt> 1147 <dd><p>On RISC-V targets specify the default version of the RISC-V Unprivileged 1148 (formerly User-Level) ISA specification to produce code conforming to. 1149 The possibilities for <var>ISA-spec-string</var> are: 1150 </p><dl compact="compact"> 1151 <dt><code>2.2</code></dt> 1152 <dd><p>Produce code conforming to version 2.2. 1153 </p></dd> 1154 <dt><code>20190608</code></dt> 1155 <dd><p>Produce code conforming to version 20190608. 1156 </p></dd> 1157 <dt><code>20191213</code></dt> 1158 <dd><p>Produce code conforming to version 20191213. 1159 </p></dd> 1160 </dl> 1161 <p>In the absence of this configuration option the default version is 20191213. 1162 </p> 1163 </dd> 1164 <dt><code>--enable-__cxa_atexit</code></dt> 1165 <dd><p>Define if you want to use __cxa_atexit, rather than atexit, to 1166 register C++ destructors for local statics and global objects. 1167 This is essential for fully standards-compliant handling of 1168 destructors, but requires __cxa_atexit in libc. This option is currently 1169 only available on systems with GNU libc. When enabled, this will cause 1170 <samp>-fuse-cxa-atexit</samp> to be passed by default. 1171 </p> 1172 </dd> 1173 <dt><code>--enable-gnu-indirect-function</code></dt> 1174 <dd><p>Define if you want to enable the <code>ifunc</code> attribute. This option is 1175 currently only available on systems with GNU libc on certain targets. 1176 </p> 1177 </dd> 1178 <dt><code>--enable-target-optspace</code></dt> 1179 <dd><p>Specify that target 1180 libraries should be optimized for code space instead of code speed. 1181 This is the default for the m32r platform. 1182 </p> 1183 </dd> 1184 <dt><code>--with-cpp-install-dir=<var>dirname</var></code></dt> 1185 <dd><p>Specify that the user visible <code>cpp</code> program should be installed 1186 in <samp><var>prefix</var>/<var>dirname</var>/cpp</samp>, in addition to <var>bindir</var>. 1187 </p> 1188 </dd> 1189 <dt><code>--enable-comdat</code></dt> 1190 <dd><p>Enable COMDAT group support. This is primarily used to override the 1191 automatically detected value. 1192 </p> 1193 </dd> 1194 <dt><code>--enable-initfini-array</code></dt> 1195 <dd><p>Force the use of sections <code>.init_array</code> and <code>.fini_array</code> 1196 (instead of <code>.init</code> and <code>.fini</code>) for constructors and 1197 destructors. Option <samp>--disable-initfini-array</samp> has the 1198 opposite effect. If neither option is specified, the configure script 1199 will try to guess whether the <code>.init_array</code> and 1200 <code>.fini_array</code> sections are supported and, if they are, use them. 1201 </p> 1202 </dd> 1203 <dt><code>--enable-link-mutex</code></dt> 1204 <dd><p>When building GCC, use a mutex to avoid linking the compilers for 1205 multiple languages at the same time, to avoid thrashing on build 1206 systems with limited free memory. The default is not to use such a mutex. 1207 </p> 1208 </dd> 1209 <dt><code>--enable-link-serialization</code></dt> 1210 <dd><p>When building GCC, use make dependencies to serialize linking the compilers for 1211 multiple languages, to avoid thrashing on build 1212 systems with limited free memory. The default is not to add such 1213 dependencies and thus with parallel make potentially link different 1214 compilers concurrently. If the argument is a positive integer, allow 1215 that number of concurrent link processes for the large binaries. 1216 </p> 1217 </dd> 1218 <dt><code>--enable-maintainer-mode</code></dt> 1219 <dd><p>The build rules that regenerate the Autoconf and Automake output files as 1220 well as the GCC master message catalog <samp>gcc.pot</samp> are normally 1221 disabled. This is because it can only be rebuilt if the complete source 1222 tree is present. If you have changed the sources and want to rebuild the 1223 catalog, configuring with <samp>--enable-maintainer-mode</samp> will enable 1224 this. Note that you need a recent version of the <code>gettext</code> tools 1225 to do so. 1226 </p> 1227 </dd> 1228 <dt><code>--disable-bootstrap</code></dt> 1229 <dd><p>For a native build, the default configuration is to perform 1230 a 3-stage bootstrap of the compiler when ‘<samp>make</samp>’ is invoked, 1231 testing that GCC can compile itself correctly. If you want to disable 1232 this process, you can configure with <samp>--disable-bootstrap</samp>. 1233 </p> 1234 </dd> 1235 <dt><code>--enable-bootstrap</code></dt> 1236 <dd><p>In special cases, you may want to perform a 3-stage build 1237 even if the target and host triplets are different. 1238 This is possible when the host can run code compiled for 1239 the target (e.g. host is i686-linux, target is i486-linux). 1240 Starting from GCC 4.2, to do this you have to configure explicitly 1241 with <samp>--enable-bootstrap</samp>. 1242 </p> 1243 </dd> 1244 <dt><code>--enable-generated-files-in-srcdir</code></dt> 1245 <dd><p>Neither the .c and .h files that are generated from Bison and flex nor the 1246 info manuals and man pages that are built from the .texi files are present 1247 in the repository development tree. When building GCC from that development tree, 1248 or from one of our snapshots, those generated files are placed in your 1249 build directory, which allows for the source to be in a readonly 1250 directory. 1251 </p> 1252 <p>If you configure with <samp>--enable-generated-files-in-srcdir</samp> then those 1253 generated files will go into the source directory. This is mainly intended 1254 for generating release or prerelease tarballs of the GCC sources, since it 1255 is not a requirement that the users of source releases to have flex, Bison, 1256 or makeinfo. 1257 </p> 1258 </dd> 1259 <dt><code>--enable-version-specific-runtime-libs</code></dt> 1260 <dd><p>Specify 1261 that runtime libraries should be installed in the compiler specific 1262 subdirectory (<samp><var>libdir</var>/gcc</samp>) rather than the usual places. In 1263 addition, ‘<samp>libstdc++</samp>’’s include files will be installed into 1264 <samp><var>libdir</var></samp> unless you overruled it by using 1265 <samp>--with-gxx-include-dir=<var>dirname</var></samp>. Using this option is 1266 particularly useful if you intend to use several versions of GCC in 1267 parallel. The default is ‘<samp>yes</samp>’ for ‘<samp>libada</samp>’, and ‘<samp>no</samp>’ for 1268 the remaining libraries. 1269 </p> 1270 </dd> 1271 <dt><code><a name="WithAixSoname"></a>--with-aix-soname=‘<samp>aix</samp>’, ‘<samp>svr4</samp>’ or ‘<samp>both</samp>’</code></dt> 1272 <dd><p>Traditional AIX shared library versioning (versioned <code>Shared Object</code> 1273 files as members of unversioned <code>Archive Library</code> files named 1274 ‘<samp>lib.a</samp>’) causes numerous headaches for package managers. However, 1275 <code>Import Files</code> as members of <code>Archive Library</code> files allow for 1276 <strong>filename-based versioning</strong> of shared libraries as seen on Linux/SVR4, 1277 where this is called the "SONAME". But as they prevent static linking, 1278 <code>Import Files</code> may be used with <code>Runtime Linking</code> only, where the 1279 linker does search for ‘<samp>libNAME.so</samp>’ before ‘<samp>libNAME.a</samp>’ library 1280 filenames with the ‘<samp>-lNAME</samp>’ linker flag. 1281 </p> 1282 <a name="AixLdCommand"></a><p>For detailed information please refer to the AIX 1283 <a href="https://www.ibm.com/support/knowledgecenter/search/%22the%20ld%20command%2C%20also%20called%20the%20linkage%20editor%20or%20binder%22">ld 1284 Command</a> reference. 1285 </p> 1286 <p>As long as shared library creation is enabled, upon: 1287 </p><dl compact="compact"> 1288 <dt><code>--with-aix-soname=aix</code></dt> 1289 <dt><code>--with-aix-soname=both</code></dt> 1290 <dd><p>A (traditional AIX) <code>Shared Archive Library</code> file is created: 1291 </p><ul> 1292 <li> using the ‘<samp>libNAME.a</samp>’ filename scheme 1293 </li><li> with the <code>Shared Object</code> file as archive member named 1294 ‘<samp>libNAME.so.V</samp>’ (except for ‘<samp>libgcc_s</samp>’, where the <code>Shared 1295 Object</code> file is named ‘<samp>shr.o</samp>’ for backwards compatibility), which 1296 <ul class="no-bullet"> 1297 <li>- is used for runtime loading from inside the ‘<samp>libNAME.a</samp>’ file 1298 </li><li>- is used for dynamic loading via 1299 <code>dlopen("libNAME.a(libNAME.so.V)", RTLD_MEMBER)</code> 1300 </li><li>- is used for shared linking 1301 </li><li>- is used for static linking, so no separate <code>Static Archive 1302 Library</code> file is needed 1303 </li></ul> 1304 </li></ul> 1305 </dd> 1306 <dt><code>--with-aix-soname=both</code></dt> 1307 <dt><code>--with-aix-soname=svr4</code></dt> 1308 <dd><p>A (second) <code>Shared Archive Library</code> file is created: 1309 </p><ul> 1310 <li> using the ‘<samp>libNAME.so.V</samp>’ filename scheme 1311 </li><li> with the <code>Shared Object</code> file as archive member named 1312 ‘<samp>shr.o</samp>’, which 1313 <ul class="no-bullet"> 1314 <li>- is created with the <code>-G linker flag</code> 1315 </li><li>- has the <code>F_LOADONLY</code> flag set 1316 </li><li>- is used for runtime loading from inside the ‘<samp>libNAME.so.V</samp>’ file 1317 </li><li>- is used for dynamic loading via <code>dlopen("libNAME.so.V(shr.o)", 1318 RTLD_MEMBER)</code> 1319 </li></ul> 1320 </li><li> with the <code>Import File</code> as archive member named ‘<samp>shr.imp</samp>’, 1321 which 1322 <ul class="no-bullet"> 1323 <li>- refers to ‘<samp>libNAME.so.V(shr.o)</samp>’ as the "SONAME", to be recorded 1324 in the <code>Loader Section</code> of subsequent binaries 1325 </li><li>- indicates whether ‘<samp>libNAME.so.V(shr.o)</samp>’ is 32 or 64 bit 1326 </li><li>- lists all the public symbols exported by ‘<samp>lib.so.V(shr.o)</samp>’, 1327 eventually decorated with the <code>‘<samp>weak</samp>’ Keyword</code> 1328 </li><li>- is necessary for shared linking against ‘<samp>lib.so.V(shr.o)</samp>’ 1329 </li></ul> 1330 </li></ul> 1331 <p>A symbolic link using the ‘<samp>libNAME.so</samp>’ filename scheme is created: 1332 </p><ul> 1333 <li> pointing to the ‘<samp>libNAME.so.V</samp>’ <code>Shared Archive Library</code> file 1334 </li><li> to permit the <code>ld Command</code> to find ‘<samp>lib.so.V(shr.imp)</samp>’ via 1335 the ‘<samp>-lNAME</samp>’ argument (requires <code>Runtime Linking</code> to be enabled) 1336 </li><li> to permit dynamic loading of ‘<samp>lib.so.V(shr.o)</samp>’ without the need 1337 to specify the version number via <code>dlopen("libNAME.so(shr.o)", 1338 RTLD_MEMBER)</code> 1339 </li></ul> 1340 </dd> 1341 </dl> 1342 1343 <p>As long as static library creation is enabled, upon: 1344 </p><dl compact="compact"> 1345 <dt><code>--with-aix-soname=svr4</code></dt> 1346 <dd><p>A <code>Static Archive Library</code> is created: 1347 </p><ul> 1348 <li> using the ‘<samp>libNAME.a</samp>’ filename scheme 1349 </li><li> with all the <code>Static Object</code> files as archive members, which 1350 <ul class="no-bullet"> 1351 <li>- are used for static linking 1352 </li></ul> 1353 </li></ul> 1354 </dd> 1355 </dl> 1356 1357 <p>While the aix-soname=‘<samp>svr4</samp>’ option does not create <code>Shared Object</code> 1358 files as members of unversioned <code>Archive Library</code> files any more, package 1359 managers still are responsible to 1360 <a href="./specific.html#TransferAixShobj">transfer</a> <code>Shared Object</code> files 1361 found as member of a previously installed unversioned <code>Archive Library</code> 1362 file into the newly installed <code>Archive Library</code> file with the same 1363 filename. 1364 </p> 1365 <p><em>WARNING:</em> Creating <code>Shared Object</code> files with <code>Runtime Linking</code> 1366 enabled may bloat the TOC, eventually leading to <code>TOC overflow</code> errors, 1367 requiring the use of either the <samp>-Wl,-bbigtoc</samp> linker flag (seen to 1368 break with the <code>GDB</code> debugger) or some of the TOC-related compiler flags, 1369 see “RS/6000 and PowerPC Options” in the main manual. 1370 </p> 1371 <p><samp>--with-aix-soname</samp> is currently supported by ‘<samp>libgcc_s</samp>’ only, so 1372 this option is still experimental and not for normal use yet. 1373 </p> 1374 <p>Default is the traditional behavior <samp>--with-aix-soname=‘<samp>aix</samp>’</samp>. 1375 </p> 1376 </dd> 1377 <dt><code>--enable-languages=<var>lang1</var>,<var>lang2</var>,…</code></dt> 1378 <dd><p>Specify that only a particular subset of compilers and 1379 their runtime libraries should be built. For a list of valid values for 1380 <var>langN</var> you can issue the following command in the 1381 <samp>gcc</samp> directory of your GCC source tree:<br> 1382 </p><div class="smallexample"> 1383 <pre class="smallexample">grep ^language= */config-lang.in 1384 </pre></div> 1385 <p>Currently, you can use any of the following: 1386 <code>all</code>, <code>default</code>, <code>ada</code>, <code>c</code>, <code>c++</code>, <code>d</code>, 1387 <code>fortran</code>, <code>go</code>, <code>jit</code>, <code>lto</code>, <code>objc</code>, <code>obj-c++</code>. 1388 Building the Ada compiler has special requirements, see below. 1389 If you do not pass this flag, or specify the option <code>default</code>, then the 1390 default languages available in the <samp>gcc</samp> sub-tree will be configured. 1391 Ada, D, Go, Jit, and Objective-C++ are not default languages. LTO is not a 1392 default language, but is built by default because <samp>--enable-lto</samp> is 1393 enabled by default. The other languages are default languages. If 1394 <code>all</code> is specified, then all available languages are built. An 1395 exception is <code>jit</code> language, which requires 1396 <samp>--enable-host-shared</samp> to be included with <code>all</code>. 1397 </p> 1398 </dd> 1399 <dt><code>--enable-stage1-languages=<var>lang1</var>,<var>lang2</var>,…</code></dt> 1400 <dd><p>Specify that a particular subset of compilers and their runtime 1401 libraries should be built with the system C compiler during stage 1 of 1402 the bootstrap process, rather than only in later stages with the 1403 bootstrapped C compiler. The list of valid values is the same as for 1404 <samp>--enable-languages</samp>, and the option <code>all</code> will select all 1405 of the languages enabled by <samp>--enable-languages</samp>. This option is 1406 primarily useful for GCC development; for instance, when a development 1407 version of the compiler cannot bootstrap due to compiler bugs, or when 1408 one is debugging front ends other than the C front end. When this 1409 option is used, one can then build the target libraries for the 1410 specified languages with the stage-1 compiler by using <code>make 1411 stage1-bubble all-target</code>, or run the testsuite on the stage-1 compiler 1412 for the specified languages using <code>make stage1-start check-gcc</code>. 1413 </p> 1414 </dd> 1415 <dt><code>--disable-libada</code></dt> 1416 <dd><p>Specify that the run-time libraries and tools used by GNAT should not 1417 be built. This can be useful for debugging, or for compatibility with 1418 previous Ada build procedures, when it was required to explicitly 1419 do a ‘<samp>make -C gcc gnatlib_and_tools</samp>’. 1420 </p> 1421 </dd> 1422 <dt><code>--disable-libsanitizer</code></dt> 1423 <dd><p>Specify that the run-time libraries for the various sanitizers should 1424 not be built. 1425 </p> 1426 </dd> 1427 <dt><code>--disable-libssp</code></dt> 1428 <dd><p>Specify that the run-time libraries for stack smashing protection 1429 should not be built or linked against. On many targets library support 1430 is provided by the C library instead. 1431 </p> 1432 </dd> 1433 <dt><code>--disable-libquadmath</code></dt> 1434 <dd><p>Specify that the GCC quad-precision math library should not be built. 1435 On some systems, the library is required to be linkable when building 1436 the Fortran front end, unless <samp>--disable-libquadmath-support</samp> 1437 is used. 1438 </p> 1439 </dd> 1440 <dt><code>--disable-libquadmath-support</code></dt> 1441 <dd><p>Specify that the Fortran front end and <code>libgfortran</code> do not add 1442 support for <code>libquadmath</code> on systems supporting it. 1443 </p> 1444 </dd> 1445 <dt><code>--disable-libgomp</code></dt> 1446 <dd><p>Specify that the GNU Offloading and Multi Processing Runtime Library 1447 should not be built. 1448 </p> 1449 </dd> 1450 <dt><code>--disable-libvtv</code></dt> 1451 <dd><p>Specify that the run-time libraries used by vtable verification 1452 should not be built. 1453 </p> 1454 </dd> 1455 <dt><code>--with-dwarf2</code></dt> 1456 <dd><p>Specify that the compiler should 1457 use DWARF 2 debugging information as the default. 1458 </p> 1459 </dd> 1460 <dt><code>--with-advance-toolchain=<var>at</var></code></dt> 1461 <dd><p>On 64-bit PowerPC Linux systems, configure the compiler to use the 1462 header files, library files, and the dynamic linker from the Advance 1463 Toolchain release <var>at</var> instead of the default versions that are 1464 provided by the Linux distribution. In general, this option is 1465 intended for the developers of GCC, and it is not intended for general 1466 use. 1467 </p> 1468 </dd> 1469 <dt><code>--enable-targets=all</code></dt> 1470 <dt><code>--enable-targets=<var>target_list</var></code></dt> 1471 <dd><p>Some GCC targets, e.g. powerpc64-linux, build bi-arch compilers. 1472 These are compilers that are able to generate either 64-bit or 32-bit 1473 code. Typically, the corresponding 32-bit target, e.g. 1474 powerpc-linux for powerpc64-linux, only generates 32-bit code. This 1475 option enables the 32-bit target to be a bi-arch compiler, which is 1476 useful when you want a bi-arch compiler that defaults to 32-bit, and 1477 you are building a bi-arch or multi-arch binutils in a combined tree. 1478 On mips-linux, this will build a tri-arch compiler (ABI o32/n32/64), 1479 defaulted to o32. 1480 Currently, this option only affects sparc-linux, powerpc-linux, x86-linux, 1481 mips-linux and s390-linux. 1482 </p> 1483 </dd> 1484 <dt><code>--enable-default-pie</code></dt> 1485 <dd><p>Turn on <samp>-fPIE</samp> and <samp>-pie</samp> by default. 1486 </p> 1487 </dd> 1488 <dt><code>--enable-secureplt</code></dt> 1489 <dd><p>This option enables <samp>-msecure-plt</samp> by default for powerpc-linux. 1490 See “RS/6000 and PowerPC Options” in the main manual 1491 </p> 1492 </dd> 1493 <dt><code>--enable-default-ssp</code></dt> 1494 <dd><p>Turn on <samp>-fstack-protector-strong</samp> by default. 1495 </p> 1496 </dd> 1497 <dt><code>--enable-cld</code></dt> 1498 <dd><p>This option enables <samp>-mcld</samp> by default for 32-bit x86 targets. 1499 See “i386 and x86-64 Options” in the main manual 1500 </p> 1501 </dd> 1502 <dt><code>--enable-large-address-aware</code></dt> 1503 <dd><p>The <samp>--enable-large-address-aware</samp> option arranges for MinGW 1504 executables to be linked using the <samp>--large-address-aware</samp> 1505 option, that enables the use of more than 2GB of memory. If GCC is 1506 configured with this option, its effects can be reversed by passing the 1507 <samp>-Wl,--disable-large-address-aware</samp> option to the so-configured 1508 compiler driver. 1509 </p> 1510 </dd> 1511 <dt><code>--enable-win32-registry</code></dt> 1512 <dt><code>--enable-win32-registry=<var>key</var></code></dt> 1513 <dt><code>--disable-win32-registry</code></dt> 1514 <dd><p>The <samp>--enable-win32-registry</samp> option enables Microsoft Windows-hosted GCC 1515 to look up installations paths in the registry using the following key: 1516 </p> 1517 <div class="smallexample"> 1518 <pre class="smallexample"><code>HKEY_LOCAL_MACHINE\SOFTWARE\Free Software Foundation\<var>key</var></code> 1519 </pre></div> 1520 1521 <p><var>key</var> defaults to GCC version number, and can be overridden by the 1522 <samp>--enable-win32-registry=<var>key</var></samp> option. Vendors and distributors 1523 who use custom installers are encouraged to provide a different key, 1524 perhaps one comprised of vendor name and GCC version number, to 1525 avoid conflict with existing installations. This feature is enabled 1526 by default, and can be disabled by <samp>--disable-win32-registry</samp> 1527 option. This option has no effect on the other hosts. 1528 </p> 1529 </dd> 1530 <dt><code>--nfp</code></dt> 1531 <dd><p>Specify that the machine does not have a floating point unit. This 1532 option only applies to ‘<samp>m68k-sun-sunos<var>n</var></samp>’. On any other 1533 system, <samp>--nfp</samp> has no effect. 1534 </p> 1535 </dd> 1536 <dt><code>--enable-werror</code></dt> 1537 <dt><code>--disable-werror</code></dt> 1538 <dt><code>--enable-werror=yes</code></dt> 1539 <dt><code>--enable-werror=no</code></dt> 1540 <dd><p>When you specify this option, it controls whether certain files in the 1541 compiler are built with <samp>-Werror</samp> in bootstrap stage2 and later. 1542 If you don’t specify it, <samp>-Werror</samp> is turned on for the main 1543 development trunk. However it defaults to off for release branches and 1544 final releases. The specific files which get <samp>-Werror</samp> are 1545 controlled by the Makefiles. 1546 </p> 1547 </dd> 1548 <dt><code>--enable-checking</code></dt> 1549 <dt><code>--disable-checking</code></dt> 1550 <dt><code>--enable-checking=<var>list</var></code></dt> 1551 <dd><p>This option controls performing internal consistency checks in the compiler. 1552 It does not change the generated code, but adds error checking of the 1553 requested complexity. This slows down the compiler and may only work 1554 properly if you are building the compiler with GCC. 1555 </p> 1556 <p>When the option is not specified, the active set of checks depends on context. 1557 Namely, bootstrap stage 1 defaults to ‘<samp>--enable-checking=yes</samp>’, builds 1558 from release branches or release archives default to 1559 ‘<samp>--enable-checking=release</samp>’, and otherwise 1560 ‘<samp>--enable-checking=yes,extra</samp>’ is used. When the option is 1561 specified without a <var>list</var>, the result is the same as 1562 ‘<samp>--enable-checking=yes</samp>’. Likewise, ‘<samp>--disable-checking</samp>’ is 1563 equivalent to ‘<samp>--enable-checking=no</samp>’. 1564 </p> 1565 <p>The categories of checks available in <var>list</var> are ‘<samp>yes</samp>’ (most common 1566 checks ‘<samp>assert,misc,gc,gimple,rtlflag,runtime,tree,types</samp>’), ‘<samp>no</samp>’ 1567 (no checks at all), ‘<samp>all</samp>’ (all but ‘<samp>valgrind</samp>’), ‘<samp>release</samp>’ 1568 (cheapest checks ‘<samp>assert,runtime</samp>’) or ‘<samp>none</samp>’ (same as ‘<samp>no</samp>’). 1569 ‘<samp>release</samp>’ checks are always on and to disable them 1570 ‘<samp>--disable-checking</samp>’ or ‘<samp>--enable-checking=no[,<other checks>]</samp>’ 1571 must be explicitly requested. Disabling assertions makes the compiler and 1572 runtime slightly faster but increases the risk of undetected internal errors 1573 causing wrong code to be generated. 1574 </p> 1575 <p>Individual checks can be enabled with these flags: ‘<samp>assert</samp>’, ‘<samp>df</samp>’, 1576 ‘<samp>extra</samp>’, ‘<samp>fold</samp>’, ‘<samp>gc</samp>’, ‘<samp>gcac</samp>’, ‘<samp>gimple</samp>’, 1577 ‘<samp>misc</samp>’, ‘<samp>rtl</samp>’, ‘<samp>rtlflag</samp>’, ‘<samp>runtime</samp>’, ‘<samp>tree</samp>’, 1578 ‘<samp>types</samp>’ and ‘<samp>valgrind</samp>’. ‘<samp>extra</samp>’ extends ‘<samp>misc</samp>’ 1579 checking with extra checks that might affect code generation and should 1580 therefore not differ between stage1 and later stages in bootstrap. 1581 </p> 1582 <p>The ‘<samp>valgrind</samp>’ check requires the external <code>valgrind</code> simulator, 1583 available from <a href="https://valgrind.org">https://valgrind.org</a>. The ‘<samp>rtl</samp>’ checks are 1584 expensive and the ‘<samp>df</samp>’, ‘<samp>gcac</samp>’ and ‘<samp>valgrind</samp>’ checks are very 1585 expensive. 1586 </p> 1587 </dd> 1588 <dt><code>--disable-stage1-checking</code></dt> 1589 <dt><code>--enable-stage1-checking</code></dt> 1590 <dt><code>--enable-stage1-checking=<var>list</var></code></dt> 1591 <dd><p>This option affects only bootstrap build. If no <samp>--enable-checking</samp> 1592 option is specified the stage1 compiler is built with ‘<samp>yes</samp>’ checking 1593 enabled, otherwise the stage1 checking flags are the same as specified by 1594 <samp>--enable-checking</samp>. To build the stage1 compiler with 1595 different checking options use <samp>--enable-stage1-checking</samp>. 1596 The list of checking options is the same as for <samp>--enable-checking</samp>. 1597 If your system is too slow or too small to bootstrap a released compiler 1598 with checking for stage1 enabled, you can use ‘<samp>--disable-stage1-checking</samp>’ 1599 to disable checking for the stage1 compiler. 1600 </p> 1601 </dd> 1602 <dt><code>--enable-coverage</code></dt> 1603 <dt><code>--enable-coverage=<var>level</var></code></dt> 1604 <dd><p>With this option, the compiler is built to collect self coverage 1605 information, every time it is run. This is for internal development 1606 purposes, and only works when the compiler is being built with gcc. The 1607 <var>level</var> argument controls whether the compiler is built optimized or 1608 not, values are ‘<samp>opt</samp>’ and ‘<samp>noopt</samp>’. For coverage analysis you 1609 want to disable optimization, for performance analysis you want to 1610 enable optimization. When coverage is enabled, the default level is 1611 without optimization. 1612 </p> 1613 </dd> 1614 <dt><code>--enable-gather-detailed-mem-stats</code></dt> 1615 <dd><p>When this option is specified more detailed information on memory 1616 allocation is gathered. This information is printed when using 1617 <samp>-fmem-report</samp>. 1618 </p> 1619 </dd> 1620 <dt><code>--enable-valgrind-annotations</code></dt> 1621 <dd><p>Mark selected memory related operations in the compiler when run under 1622 valgrind to suppress false positives. 1623 </p> 1624 </dd> 1625 <dt><code>--enable-nls</code></dt> 1626 <dt><code>--disable-nls</code></dt> 1627 <dd><p>The <samp>--enable-nls</samp> option enables Native Language Support (NLS), 1628 which lets GCC output diagnostics in languages other than American 1629 English. Native Language Support is enabled by default if not doing a 1630 canadian cross build. The <samp>--disable-nls</samp> option disables NLS. 1631 </p> 1632 </dd> 1633 <dt><code>--with-included-gettext</code></dt> 1634 <dd><p>If NLS is enabled, the <samp>--with-included-gettext</samp> option causes the build 1635 procedure to prefer its copy of GNU <code>gettext</code>. 1636 </p> 1637 </dd> 1638 <dt><code>--with-catgets</code></dt> 1639 <dd><p>If NLS is enabled, and if the host lacks <code>gettext</code> but has the 1640 inferior <code>catgets</code> interface, the GCC build procedure normally 1641 ignores <code>catgets</code> and instead uses GCC’s copy of the GNU 1642 <code>gettext</code> library. The <samp>--with-catgets</samp> option causes the 1643 build procedure to use the host’s <code>catgets</code> in this situation. 1644 </p> 1645 </dd> 1646 <dt><code>--with-libiconv-prefix=<var>dir</var></code></dt> 1647 <dd><p>Search for libiconv header files in <samp><var>dir</var>/include</samp> and 1648 libiconv library files in <samp><var>dir</var>/lib</samp>. 1649 </p> 1650 </dd> 1651 <dt><code>--enable-obsolete</code></dt> 1652 <dd><p>Enable configuration for an obsoleted system. If you attempt to 1653 configure GCC for a system (build, host, or target) which has been 1654 obsoleted, and you do not specify this flag, configure will halt with an 1655 error message. 1656 </p> 1657 <p>All support for systems which have been obsoleted in one release of GCC 1658 is removed entirely in the next major release, unless someone steps 1659 forward to maintain the port. 1660 </p> 1661 </dd> 1662 <dt><code>--enable-decimal-float</code></dt> 1663 <dt><code>--enable-decimal-float=yes</code></dt> 1664 <dt><code>--enable-decimal-float=no</code></dt> 1665 <dt><code>--enable-decimal-float=bid</code></dt> 1666 <dt><code>--enable-decimal-float=dpd</code></dt> 1667 <dt><code>--disable-decimal-float</code></dt> 1668 <dd><p>Enable (or disable) support for the C decimal floating point extension 1669 that is in the IEEE 754-2008 standard. This is enabled by default only 1670 on PowerPC, i386, and x86_64 GNU/Linux systems. Other systems may also 1671 support it, but require the user to specifically enable it. You can 1672 optionally control which decimal floating point format is used (either 1673 ‘<samp>bid</samp>’ or ‘<samp>dpd</samp>’). The ‘<samp>bid</samp>’ (binary integer decimal) 1674 format is default on i386 and x86_64 systems, and the ‘<samp>dpd</samp>’ 1675 (densely packed decimal) format is default on PowerPC systems. 1676 </p> 1677 </dd> 1678 <dt><code>--enable-fixed-point</code></dt> 1679 <dt><code>--disable-fixed-point</code></dt> 1680 <dd><p>Enable (or disable) support for C fixed-point arithmetic. 1681 This option is enabled by default for some targets (such as MIPS) which 1682 have hardware-support for fixed-point operations. On other targets, you 1683 may enable this option manually. 1684 </p> 1685 </dd> 1686 <dt><code>--with-long-double-128</code></dt> 1687 <dd><p>Specify if <code>long double</code> type should be 128-bit by default on selected 1688 GNU/Linux architectures. If using <code>--without-long-double-128</code>, 1689 <code>long double</code> will be by default 64-bit, the same as <code>double</code> type. 1690 When neither of these configure options are used, the default will be 1691 128-bit <code>long double</code> when built against GNU C Library 2.4 and later, 1692 64-bit <code>long double</code> otherwise. 1693 </p> 1694 </dd> 1695 <dt><code>--with-long-double-format=ibm</code></dt> 1696 <dt><code>--with-long-double-format=ieee</code></dt> 1697 <dd><p>Specify whether <code>long double</code> uses the IBM extended double format 1698 or the IEEE 128-bit floating point format on PowerPC Linux systems. 1699 This configuration switch will only work on little endian PowerPC 1700 Linux systems and on big endian 64-bit systems where the default cpu 1701 is at least power7 (i.e. <samp>--with-cpu=power7</samp>, 1702 <samp>--with-cpu=power8</samp>, or <samp>--with-cpu=power9</samp> is used). 1703 </p> 1704 <p>If you use the <samp>--with-long-double-64</samp> configuration option, 1705 the <samp>--with-long-double-format=ibm</samp> and 1706 <samp>--with-long-double-format=ieee</samp> options are ignored. 1707 </p> 1708 <p>The default <code>long double</code> format is to use IBM extended double. 1709 Until all of the libraries are converted to use IEEE 128-bit floating 1710 point, it is not recommended to use 1711 <samp>--with-long-double-format=ieee</samp>. 1712 </p> 1713 </dd> 1714 <dt><code>--enable-fdpic</code></dt> 1715 <dd><p>On SH Linux systems, generate ELF FDPIC code. 1716 </p> 1717 </dd> 1718 <dt><code>--with-gmp=<var>pathname</var></code></dt> 1719 <dt><code>--with-gmp-include=<var>pathname</var></code></dt> 1720 <dt><code>--with-gmp-lib=<var>pathname</var></code></dt> 1721 <dt><code>--with-mpfr=<var>pathname</var></code></dt> 1722 <dt><code>--with-mpfr-include=<var>pathname</var></code></dt> 1723 <dt><code>--with-mpfr-lib=<var>pathname</var></code></dt> 1724 <dt><code>--with-mpc=<var>pathname</var></code></dt> 1725 <dt><code>--with-mpc-include=<var>pathname</var></code></dt> 1726 <dt><code>--with-mpc-lib=<var>pathname</var></code></dt> 1727 <dd><p>If you want to build GCC but do not have the GMP library, the MPFR 1728 library and/or the MPC library installed in a standard location and 1729 do not have their sources present in the GCC source tree then you 1730 can explicitly specify the directory where they are installed 1731 (‘<samp>--with-gmp=<var>gmpinstalldir</var></samp>’, 1732 ‘<samp>--with-mpfr=<var>mpfrinstalldir</var></samp>’, 1733 ‘<samp>--with-mpc=<var>mpcinstalldir</var></samp>’). The 1734 <samp>--with-gmp=<var>gmpinstalldir</var></samp> option is shorthand for 1735 <samp>--with-gmp-lib=<var>gmpinstalldir</var>/lib</samp> and 1736 <samp>--with-gmp-include=<var>gmpinstalldir</var>/include</samp>. Likewise the 1737 <samp>--with-mpfr=<var>mpfrinstalldir</var></samp> option is shorthand for 1738 <samp>--with-mpfr-lib=<var>mpfrinstalldir</var>/lib</samp> and 1739 <samp>--with-mpfr-include=<var>mpfrinstalldir</var>/include</samp>, also the 1740 <samp>--with-mpc=<var>mpcinstalldir</var></samp> option is shorthand for 1741 <samp>--with-mpc-lib=<var>mpcinstalldir</var>/lib</samp> and 1742 <samp>--with-mpc-include=<var>mpcinstalldir</var>/include</samp>. If these 1743 shorthand assumptions are not correct, you can use the explicit 1744 include and lib options directly. You might also need to ensure the 1745 shared libraries can be found by the dynamic linker when building and 1746 using GCC, for example by setting the runtime shared library path 1747 variable (<code>LD_LIBRARY_PATH</code> on GNU/Linux and Solaris systems). 1748 </p> 1749 <p>These flags are applicable to the host platform only. When building 1750 a cross compiler, they will not be used to configure target libraries. 1751 </p> 1752 </dd> 1753 <dt><code>--with-isl=<var>pathname</var></code></dt> 1754 <dt><code>--with-isl-include=<var>pathname</var></code></dt> 1755 <dt><code>--with-isl-lib=<var>pathname</var></code></dt> 1756 <dd><p>If you do not have the isl library installed in a standard location and you 1757 want to build GCC, you can explicitly specify the directory where it is 1758 installed (‘<samp>--with-isl=<var>islinstalldir</var></samp>’). The 1759 <samp>--with-isl=<var>islinstalldir</var></samp> option is shorthand for 1760 <samp>--with-isl-lib=<var>islinstalldir</var>/lib</samp> and 1761 <samp>--with-isl-include=<var>islinstalldir</var>/include</samp>. If this 1762 shorthand assumption is not correct, you can use the explicit 1763 include and lib options directly. 1764 </p> 1765 <p>These flags are applicable to the host platform only. When building 1766 a cross compiler, they will not be used to configure target libraries. 1767 </p> 1768 </dd> 1769 <dt><code>--with-stage1-ldflags=<var>flags</var></code></dt> 1770 <dd><p>This option may be used to set linker flags to be used when linking 1771 stage 1 of GCC. These are also used when linking GCC if configured with 1772 <samp>--disable-bootstrap</samp>. If <samp>--with-stage1-libs</samp> is not set to a 1773 value, then the default is ‘<samp>-static-libstdc++ -static-libgcc</samp>’, if 1774 supported. 1775 </p> 1776 </dd> 1777 <dt><code>--with-stage1-libs=<var>libs</var></code></dt> 1778 <dd><p>This option may be used to set libraries to be used when linking stage 1 1779 of GCC. These are also used when linking GCC if configured with 1780 <samp>--disable-bootstrap</samp>. 1781 </p> 1782 </dd> 1783 <dt><code>--with-boot-ldflags=<var>flags</var></code></dt> 1784 <dd><p>This option may be used to set linker flags to be used when linking 1785 stage 2 and later when bootstrapping GCC. If –with-boot-libs 1786 is not is set to a value, then the default is 1787 ‘<samp>-static-libstdc++ -static-libgcc</samp>’. 1788 </p> 1789 </dd> 1790 <dt><code>--with-boot-libs=<var>libs</var></code></dt> 1791 <dd><p>This option may be used to set libraries to be used when linking stage 2 1792 and later when bootstrapping GCC. 1793 </p> 1794 </dd> 1795 <dt><code>--with-debug-prefix-map=<var>map</var></code></dt> 1796 <dd><p>Convert source directory names using <samp>-fdebug-prefix-map</samp> when 1797 building runtime libraries. ‘<samp><var>map</var></samp>’ is a space-separated 1798 list of maps of the form ‘<samp><var>old</var>=<var>new</var></samp>’. 1799 </p> 1800 </dd> 1801 <dt><code>--enable-linker-build-id</code></dt> 1802 <dd><p>Tells GCC to pass <samp>--build-id</samp> option to the linker for all final 1803 links (links performed without the <samp>-r</samp> or <samp>--relocatable</samp> 1804 option), if the linker supports it. If you specify 1805 <samp>--enable-linker-build-id</samp>, but your linker does not 1806 support <samp>--build-id</samp> option, a warning is issued and the 1807 <samp>--enable-linker-build-id</samp> option is ignored. The default is off. 1808 </p> 1809 </dd> 1810 <dt><code>--with-linker-hash-style=<var>choice</var></code></dt> 1811 <dd><p>Tells GCC to pass <samp>--hash-style=<var>choice</var></samp> option to the 1812 linker for all final links. <var>choice</var> can be one of 1813 ‘<samp>sysv</samp>’, ‘<samp>gnu</samp>’, and ‘<samp>both</samp>’ where ‘<samp>sysv</samp>’ is the default. 1814 </p> 1815 </dd> 1816 <dt><code>--enable-gnu-unique-object</code></dt> 1817 <dt><code>--disable-gnu-unique-object</code></dt> 1818 <dd><p>Tells GCC to use the gnu_unique_object relocation for C++ template 1819 static data members and inline function local statics. Enabled by 1820 default for a toolchain with an assembler that accepts it and 1821 GLIBC 2.11 or above, otherwise disabled. 1822 </p> 1823 </dd> 1824 <dt><code>--with-diagnostics-color=<var>choice</var></code></dt> 1825 <dd><p>Tells GCC to use <var>choice</var> as the default for <samp>-fdiagnostics-color=</samp> 1826 option (if not used explicitly on the command line). <var>choice</var> 1827 can be one of ‘<samp>never</samp>’, ‘<samp>auto</samp>’, ‘<samp>always</samp>’, and ‘<samp>auto-if-env</samp>’ 1828 where ‘<samp>auto</samp>’ is the default. ‘<samp>auto-if-env</samp>’ makes 1829 <samp>-fdiagnostics-color=auto</samp> the default if <code>GCC_COLORS</code> 1830 is present and non-empty in the environment of the compiler, and 1831 <samp>-fdiagnostics-color=never</samp> otherwise. 1832 </p> 1833 </dd> 1834 <dt><code>--with-diagnostics-urls=<var>choice</var></code></dt> 1835 <dd><p>Tells GCC to use <var>choice</var> as the default for <samp>-fdiagnostics-urls=</samp> 1836 option (if not used explicitly on the command line). <var>choice</var> 1837 can be one of ‘<samp>never</samp>’, ‘<samp>auto</samp>’, ‘<samp>always</samp>’, and ‘<samp>auto-if-env</samp>’ 1838 where ‘<samp>auto</samp>’ is the default. ‘<samp>auto-if-env</samp>’ makes 1839 <samp>-fdiagnostics-urls=auto</samp> the default if <code>GCC_URLS</code> 1840 or <code>TERM_URLS</code> is present and non-empty in the environment of the 1841 compiler, and <samp>-fdiagnostics-urls=never</samp> otherwise. 1842 </p> 1843 </dd> 1844 <dt><code>--enable-lto</code></dt> 1845 <dt><code>--disable-lto</code></dt> 1846 <dd><p>Enable support for link-time optimization (LTO). This is enabled by 1847 default, and may be disabled using <samp>--disable-lto</samp>. 1848 </p> 1849 </dd> 1850 <dt><code>--enable-linker-plugin-configure-flags=FLAGS</code></dt> 1851 <dt><code>--enable-linker-plugin-flags=FLAGS</code></dt> 1852 <dd><p>By default, linker plugins (such as the LTO plugin) are built for the 1853 host system architecture. For the case that the linker has a 1854 different (but run-time compatible) architecture, these flags can be 1855 specified to build plugins that are compatible to the linker. For 1856 example, if you are building GCC for a 64-bit x86_64 1857 (‘<samp>x86_64-pc-linux-gnu</samp>’) host system, but have a 32-bit x86 1858 GNU/Linux (‘<samp>i686-pc-linux-gnu</samp>’) linker executable (which is 1859 executable on the former system), you can configure GCC as follows for 1860 getting compatible linker plugins: 1861 </p> 1862 <div class="smallexample"> 1863 <pre class="smallexample">% <var>srcdir</var>/configure \ 1864 --host=x86_64-pc-linux-gnu \ 1865 --enable-linker-plugin-configure-flags=--host=i686-pc-linux-gnu \ 1866 --enable-linker-plugin-flags='CC=gcc\ -m32\ -Wl,-rpath,[...]/i686-pc-linux-gnu/lib' 1867 </pre></div> 1868 1869 </dd> 1870 <dt><code>--with-plugin-ld=<var>pathname</var></code></dt> 1871 <dd><p>Enable an alternate linker to be used at link-time optimization (LTO) 1872 link time when <samp>-fuse-linker-plugin</samp> is enabled. 1873 This linker should have plugin support such as gold starting with 1874 version 2.20 or GNU ld starting with version 2.21. 1875 See <samp>-fuse-linker-plugin</samp> for details. 1876 </p> 1877 </dd> 1878 <dt><code>--enable-canonical-system-headers</code></dt> 1879 <dt><code>--disable-canonical-system-headers</code></dt> 1880 <dd><p>Enable system header path canonicalization for <samp>libcpp</samp>. This can 1881 produce shorter header file paths in diagnostics and dependency output 1882 files, but these changed header paths may conflict with some compilation 1883 environments. Enabled by default, and may be disabled using 1884 <samp>--disable-canonical-system-headers</samp>. 1885 </p> 1886 </dd> 1887 <dt><code>--with-glibc-version=<var>major</var>.<var>minor</var></code></dt> 1888 <dd><p>Tell GCC that when the GNU C Library (glibc) is used on the target it 1889 will be version <var>major</var>.<var>minor</var> or later. Normally this can 1890 be detected from the C library’s header files, but this option may be 1891 needed when bootstrapping a cross toolchain without the header files 1892 available for building the initial bootstrap compiler. 1893 </p> 1894 <p>If GCC is configured with some multilibs that use glibc and some that 1895 do not, this option applies only to the multilibs that use glibc. 1896 However, such configurations may not work well as not all the relevant 1897 configuration in GCC is on a per-multilib basis. 1898 </p> 1899 </dd> 1900 <dt><code>--enable-as-accelerator-for=<var>target</var></code></dt> 1901 <dd><p>Build as offload target compiler. Specify offload host triple by <var>target</var>. 1902 </p> 1903 </dd> 1904 <dt><code>--enable-offload-targets=<var>target1</var>[=<var>path1</var>],…,<var>targetN</var>[=<var>pathN</var>]</code></dt> 1905 <dd><p>Enable offloading to targets <var>target1</var>, …, <var>targetN</var>. 1906 Offload compilers are expected to be already installed. Default search 1907 path for them is <samp><var>exec-prefix</var></samp>, but it can be changed by 1908 specifying paths <var>path1</var>, …, <var>pathN</var>. 1909 </p> 1910 <div class="smallexample"> 1911 <pre class="smallexample">% <var>srcdir</var>/configure \ 1912 --enable-offload-targets=x86_64-intelmicemul-linux-gnu=/path/to/x86_64/compiler,nvptx-none 1913 </pre></div> 1914 1915 </dd> 1916 <dt><code>--enable-offload-defaulted</code></dt> 1917 <dd> 1918 <p>Tell GCC that configured but not installed offload compilers and libgomp 1919 plugins are silently ignored. Useful for distribution compilers where 1920 those are in separate optional packages and where the presence or absence 1921 of those optional packages should determine the actual supported offloading 1922 target set rather than the GCC configure-time selection. 1923 </p> 1924 </dd> 1925 <dt><code>--with-hsa-runtime=<var>pathname</var></code></dt> 1926 <dt><code>--with-hsa-runtime-include=<var>pathname</var></code></dt> 1927 <dt><code>--with-hsa-runtime-lib=<var>pathname</var></code></dt> 1928 <dd> 1929 <p>If you configure GCC with offloading which uses an HSA run-time such as 1930 AMDGCN but do not have the HSA run-time library installed in a standard 1931 location then you can explicitly specify the directory where they are 1932 installed. The <samp>--with-hsa-runtime=<var>hsainstalldir</var></samp> option 1933 is a shorthand for 1934 <samp>--with-hsa-runtime-lib=<var>hsainstalldir</var>/lib</samp> and 1935 <samp>--with-hsa-runtime-include=<var>hsainstalldir</var>/include</samp>. 1936 </p> 1937 </dd> 1938 <dt><code>--enable-cet</code></dt> 1939 <dt><code>--disable-cet</code></dt> 1940 <dd><p>Enable building target run-time libraries with control-flow 1941 instrumentation, see <samp>-fcf-protection</samp> option. When 1942 <code>--enable-cet</code> is specified target libraries are configured 1943 to add <samp>-fcf-protection</samp> and, if needed, other target 1944 specific options to a set of building options. 1945 </p> 1946 <p><code>--enable-cet=auto</code> is default. CET is enabled on Linux/x86 if 1947 target binutils supports <code>Intel CET</code> instructions and disabled 1948 otherwise. In this case, the target libraries are configured to get 1949 additional <samp>-fcf-protection</samp> option. 1950 </p> 1951 </dd> 1952 <dt><code>--with-riscv-attribute=‘<samp>yes</samp>’, ‘<samp>no</samp>’ or ‘<samp>default</samp>’</code></dt> 1953 <dd><p>Generate RISC-V attribute by default, in order to record extra build 1954 information in object. 1955 </p> 1956 <p>The option is disabled by default. It is enabled on RISC-V/ELF (bare-metal) 1957 target if target binutils supported. 1958 </p> 1959 </dd> 1960 <dt><code>--enable-s390-excess-float-precision</code></dt> 1961 <dt><code>--disable-s390-excess-float-precision</code></dt> 1962 <dd><p>On s390(x) targets, enable treatment of float expressions with double precision 1963 when in standards-compliant mode (e.g., when <code>--std=c99</code> or 1964 <code>-fexcess-precision=standard</code> are given). 1965 </p> 1966 <p>For a native build and cross compiles that have target headers, the option’s 1967 default is derived from glibc’s behavior. When glibc clamps float_t to double, 1968 GCC follows and enables the option. For other cross compiles, the default is 1969 disabled. 1970 </p> 1971 </dd> 1972 <dt><code>--with-zstd=<var>pathname</var></code></dt> 1973 <dt><code>--with-zstd-include=<var>pathname</var></code></dt> 1974 <dt><code>--with-zstd-lib=<var>pathname</var></code></dt> 1975 <dd><p>If you do not have the <code>zstd</code> library installed in a standard 1976 location and you want to build GCC, you can explicitly specify the 1977 directory where it is installed (‘<samp>--with-zstd=<var>zstdinstalldir</var></samp>’). 1978 The <samp>--with-zstd=<var>zstdinstalldir</var></samp> option is shorthand for 1979 <samp>--with-zstd-lib=<var>zstdinstalldir</var>/lib</samp> and 1980 <samp>--with-zstd-include=<var>zstdinstalldir</var>/include</samp>. If this 1981 shorthand assumption is not correct, you can use the explicit 1982 include and lib options directly. 1983 </p> 1984 <p>These flags are applicable to the host platform only. When building 1985 a cross compiler, they will not be used to configure target libraries. 1986 </p></dd> 1987 </dl> 1988 1989 <a name="Cross-Compiler-Specific-Options"></a> 1990 <h4 class="subheading">Cross-Compiler-Specific Options</h4> 1991 <p>The following options only apply to building cross compilers. 1992 </p> 1993 <dl compact="compact"> 1994 <dt><code>--with-toolexeclibdir=<var>dir</var></code></dt> 1995 <dd><p>Specify the installation directory for libraries built with a cross compiler. 1996 The default is <samp>${gcc_tooldir}/lib</samp>. 1997 </p> 1998 </dd> 1999 <dt><code>--with-sysroot</code></dt> 2000 <dt><code>--with-sysroot=<var>dir</var></code></dt> 2001 <dd><p>Tells GCC to consider <var>dir</var> as the root of a tree that contains 2002 (a subset of) the root filesystem of the target operating system. 2003 Target system headers, libraries and run-time object files will be 2004 searched for in there. More specifically, this acts as if 2005 <samp>--sysroot=<var>dir</var></samp> was added to the default options of the built 2006 compiler. The specified directory is not copied into the 2007 install tree, unlike the options <samp>--with-headers</samp> and 2008 <samp>--with-libs</samp> that this option obsoletes. The default value, 2009 in case <samp>--with-sysroot</samp> is not given an argument, is 2010 <samp>${gcc_tooldir}/sys-root</samp>. If the specified directory is a 2011 subdirectory of <samp>${exec_prefix}</samp>, then it will be found relative to 2012 the GCC binaries if the installation tree is moved. 2013 </p> 2014 <p>This option affects the system root for the compiler used to build 2015 target libraries (which runs on the build system) and the compiler newly 2016 installed with <code>make install</code>; it does not affect the compiler which is 2017 used to build GCC itself. 2018 </p> 2019 <p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp> 2020 option then the compiler will search that directory within <var>dirname</var> for 2021 native system headers rather than the default <samp>/usr/include</samp>. 2022 </p> 2023 </dd> 2024 <dt><code>--with-build-sysroot</code></dt> 2025 <dt><code>--with-build-sysroot=<var>dir</var></code></dt> 2026 <dd><p>Tells GCC to consider <var>dir</var> as the system root (see 2027 <samp>--with-sysroot</samp>) while building target libraries, instead of 2028 the directory specified with <samp>--with-sysroot</samp>. This option is 2029 only useful when you are already using <samp>--with-sysroot</samp>. You 2030 can use <samp>--with-build-sysroot</samp> when you are configuring with 2031 <samp>--prefix</samp> set to a directory that is different from the one in 2032 which you are installing GCC and your target libraries. 2033 </p> 2034 <p>This option affects the system root for the compiler used to build 2035 target libraries (which runs on the build system); it does not affect 2036 the compiler which is used to build GCC itself. 2037 </p> 2038 <p>If you specify the <samp>--with-native-system-header-dir=<var>dirname</var></samp> 2039 option then the compiler will search that directory within <var>dirname</var> for 2040 native system headers rather than the default <samp>/usr/include</samp>. 2041 </p> 2042 </dd> 2043 <dt><code>--with-headers</code></dt> 2044 <dt><code>--with-headers=<var>dir</var></code></dt> 2045 <dd><p>Deprecated in favor of <samp>--with-sysroot</samp>. 2046 Specifies that target headers are available when building a cross compiler. 2047 The <var>dir</var> argument specifies a directory which has the target include 2048 files. These include files will be copied into the <samp>gcc</samp> install 2049 directory. <em>This option with the <var>dir</var> argument is required</em> when 2050 building a cross compiler, if <samp><var>prefix</var>/<var>target</var>/sys-include</samp> 2051 doesn’t pre-exist. If <samp><var>prefix</var>/<var>target</var>/sys-include</samp> does 2052 pre-exist, the <var>dir</var> argument may be omitted. <code>fixincludes</code> 2053 will be run on these files to make them compatible with GCC. 2054 </p> 2055 </dd> 2056 <dt><code>--without-headers</code></dt> 2057 <dd><p>Tells GCC not use any target headers from a libc when building a cross 2058 compiler. When crossing to GNU/Linux, you need the headers so GCC 2059 can build the exception handling for libgcc. 2060 </p> 2061 </dd> 2062 <dt><code>--with-libs</code></dt> 2063 <dt><code>--with-libs="<var>dir1</var> <var>dir2</var> … <var>dirN</var>"</code></dt> 2064 <dd><p>Deprecated in favor of <samp>--with-sysroot</samp>. 2065 Specifies a list of directories which contain the target runtime 2066 libraries. These libraries will be copied into the <samp>gcc</samp> install 2067 directory. If the directory list is omitted, this option has no 2068 effect. 2069 </p> 2070 </dd> 2071 <dt><code>--with-newlib</code></dt> 2072 <dd><p>Specifies that ‘<samp>newlib</samp>’ is 2073 being used as the target C library. This causes <code>__eprintf</code> to be 2074 omitted from <samp>libgcc.a</samp> on the assumption that it will be provided by 2075 ‘<samp>newlib</samp>’. 2076 </p> 2077 <a name="avr"></a> 2078 </dd> 2079 <dt><code>--with-avrlibc</code></dt> 2080 <dd><p>Only supported for the AVR target. Specifies that ‘<samp>AVR-Libc</samp>’ is 2081 being used as the target C library. This causes float support 2082 functions like <code>__addsf3</code> to be omitted from <samp>libgcc.a</samp> on 2083 the assumption that it will be provided by <samp>libm.a</samp>. For more 2084 technical details, cf. <a href="https://gcc.gnu.org/PR54461">PR54461</a>. 2085 It is not supported for 2086 RTEMS configurations, which currently use newlib. The option is 2087 supported since version 4.7.2 and is the default in 4.8.0 and newer. 2088 </p> 2089 </dd> 2090 <dt><code>--with-double={32|64|32,64|64,32}</code></dt> 2091 <dt><code>--with-long-double={32|64|32,64|64,32|double}</code></dt> 2092 <dd><p>Only supported for the AVR target since version 10. 2093 Specify the default layout available for the C/C++ ‘<samp>double</samp>’ 2094 and ‘<samp>long double</samp>’ type, respectively. The following rules apply: 2095 </p><ul> 2096 <li> The first value after the ‘<samp>=</samp>’ specifies the default layout (in bits) 2097 of the type and also the default for the <samp>-mdouble=</samp> resp. 2098 <samp>-mlong-double=</samp> compiler option. 2099 </li><li> If more than one value is specified, respective multilib variants are 2100 available, and <samp>-mdouble=</samp> resp. <samp>-mlong-double=</samp> acts 2101 as a multilib option. 2102 </li><li> If <samp>--with-long-double=double</samp> is specified, ‘<samp>double</samp>’ and 2103 ‘<samp>long double</samp>’ will have the same layout. 2104 </li><li> The defaults are <samp>--with-long-double=64,32</samp> and 2105 <samp>--with-double=32,64</samp>. The default ‘<samp>double</samp>’ layout imposed by 2106 the latter is compatible with older versions of the compiler that implement 2107 ‘<samp>double</samp>’ as a 32-bit type, which does not comply to the language standard. 2108 </li></ul> 2109 <p>Not all combinations of <samp>--with-double=</samp> and 2110 <samp>--with-long-double=</samp> are valid. For example, the combination 2111 <samp>--with-double=32,64</samp> <samp>--with-long-double=32</samp> will be 2112 rejected because the first option specifies the availability of 2113 multilibs for ‘<samp>double</samp>’, whereas the second option implies 2114 that ‘<samp>long double</samp>’ — and hence also ‘<samp>double</samp>’ — is always 2115 32 bits wide. 2116 </p> 2117 </dd> 2118 <dt><code>--with-double-comparison={tristate|bool|libf7}</code></dt> 2119 <dd><p>Only supported for the AVR target since version 10. 2120 Specify what result format is returned by library functions that 2121 compare 64-bit floating point values (<code>DFmode</code>). 2122 The GCC default is ‘<samp>tristate</samp>’. If the floating point 2123 implementation returns a boolean instead, set it to ‘<samp>bool</samp>’. 2124 </p> 2125 </dd> 2126 <dt><code>--with-libf7={libgcc|math|math-symbols|no}</code></dt> 2127 <dd><p>Only supported for the AVR target since version 10. 2128 Specify to which degree code from LibF7 is included in libgcc. 2129 LibF7 is an ad-hoc, AVR-specific, 64-bit floating point emulation 2130 written in C and (inline) assembly. ‘<samp>libgcc</samp>’ adds support 2131 for functions that one would usually expect in libgcc like double addition, 2132 double comparisons and double conversions. ‘<samp>math</samp>’ also adds routines 2133 that one would expect in <samp>libm.a</samp>, but with <code>__</code> (two underscores) 2134 prepended to the symbol names as specified by <samp>math.h</samp>. 2135 ‘<samp>math-symbols</samp>’ also defines weak aliases for the functions 2136 declared in <samp>math.h</samp>. However, <code>--with-libf7</code> won’t 2137 install no <samp>math.h</samp> header file whatsoever, this file must come 2138 from elsewhere. This option sets <samp>--with-double-comparison</samp> 2139 to ‘<samp>bool</samp>’. 2140 </p> 2141 </dd> 2142 <dt><code>--with-nds32-lib=<var>library</var></code></dt> 2143 <dd><p>Specifies that <var>library</var> setting is used for building <samp>libgcc.a</samp>. 2144 Currently, the valid <var>library</var> is ‘<samp>newlib</samp>’ or ‘<samp>mculib</samp>’. 2145 This option is only supported for the NDS32 target. 2146 </p> 2147 </dd> 2148 <dt><code>--with-build-time-tools=<var>dir</var></code></dt> 2149 <dd><p>Specifies where to find the set of target tools (assembler, linker, etc.) 2150 that will be used while building GCC itself. This option can be useful 2151 if the directory layouts are different between the system you are building 2152 GCC on, and the system where you will deploy it. 2153 </p> 2154 <p>For example, on an ‘<samp>ia64-hp-hpux</samp>’ system, you may have the GNU 2155 assembler and linker in <samp>/usr/bin</samp>, and the native tools in a 2156 different path, and build a toolchain that expects to find the 2157 native tools in <samp>/usr/bin</samp>. 2158 </p> 2159 <p>When you use this option, you should ensure that <var>dir</var> includes 2160 <code>ar</code>, <code>as</code>, <code>ld</code>, <code>nm</code>, 2161 <code>ranlib</code> and <code>strip</code> if necessary, and possibly 2162 <code>objdump</code>. Otherwise, GCC may use an inconsistent set of 2163 tools. 2164 </p></dd> 2165 </dl> 2166 2167 <a name="Overriding-configure-test-results"></a> 2168 <h4 class="subsubheading">Overriding <code>configure</code> test results</h4> 2169 2170 <p>Sometimes, it might be necessary to override the result of some 2171 <code>configure</code> test, for example in order to ease porting to a new 2172 system or work around a bug in a test. The toplevel <code>configure</code> 2173 script provides three variables for this: 2174 </p> 2175 <dl compact="compact"> 2176 <dt><code>build_configargs</code></dt> 2177 <dd><a name="index-build_005fconfigargs"></a> 2178 <p>The contents of this variable is passed to all build <code>configure</code> 2179 scripts. 2180 </p> 2181 </dd> 2182 <dt><code>host_configargs</code></dt> 2183 <dd><a name="index-host_005fconfigargs"></a> 2184 <p>The contents of this variable is passed to all host <code>configure</code> 2185 scripts. 2186 </p> 2187 </dd> 2188 <dt><code>target_configargs</code></dt> 2189 <dd><a name="index-target_005fconfigargs"></a> 2190 <p>The contents of this variable is passed to all target <code>configure</code> 2191 scripts. 2192 </p> 2193 </dd> 2194 </dl> 2195 2196 <p>In order to avoid shell and <code>make</code> quoting issues for complex 2197 overrides, you can pass a setting for <code>CONFIG_SITE</code> and set 2198 variables in the site file. 2199 </p> 2200 <a name="Objective-C-Specific-Options"></a> 2201 <h4 class="subheading">Objective-C-Specific Options</h4> 2202 2203 <p>The following options apply to the build of the Objective-C runtime library. 2204 </p> 2205 <dl compact="compact"> 2206 <dt><code>--enable-objc-gc</code></dt> 2207 <dd><p>Specify that an additional variant of the GNU Objective-C runtime library 2208 is built, using an external build of the Boehm-Demers-Weiser garbage 2209 collector (<a href="https://www.hboehm.info/gc/">https://www.hboehm.info/gc/</a>). This library needs to be 2210 available for each multilib variant, unless configured with 2211 <samp>--enable-objc-gc=‘<samp>auto</samp>’</samp> in which case the build of the 2212 additional runtime library is skipped when not available and the build 2213 continues. 2214 </p> 2215 </dd> 2216 <dt><code>--with-target-bdw-gc=<var>list</var></code></dt> 2217 <dt><code>--with-target-bdw-gc-include=<var>list</var></code></dt> 2218 <dt><code>--with-target-bdw-gc-lib=<var>list</var></code></dt> 2219 <dd><p>Specify search directories for the garbage collector header files and 2220 libraries. <var>list</var> is a comma separated list of key value pairs of the 2221 form ‘<samp><var>multilibdir</var>=<var>path</var></samp>’, where the default multilib key 2222 is named as ‘<samp>.</samp>’ (dot), or is omitted (e.g. 2223 ‘<samp>--with-target-bdw-gc=/opt/bdw-gc,32=/opt-bdw-gc32</samp>’). 2224 </p> 2225 <p>The options <samp>--with-target-bdw-gc-include</samp> and 2226 <samp>--with-target-bdw-gc-lib</samp> must always be specified together 2227 for each multilib variant and they take precedence over 2228 <samp>--with-target-bdw-gc</samp>. If <samp>--with-target-bdw-gc-include</samp> 2229 is missing values for a multilib, then the value for the default 2230 multilib is used (e.g. ‘<samp>--with-target-bdw-gc-include=/opt/bdw-gc/include</samp>’ 2231 ‘<samp>--with-target-bdw-gc-lib=/opt/bdw-gc/lib64,32=/opt-bdw-gc/lib32</samp>’). 2232 If none of these options are specified, the library is assumed in 2233 default locations. 2234 </p></dd> 2235 </dl> 2236 2237 <a name="D-Specific-Options"></a> 2238 <h4 class="subheading">D-Specific Options</h4> 2239 2240 <p>The following options apply to the build of the D runtime library. 2241 </p> 2242 <dl compact="compact"> 2243 <dt><code>--enable-libphobos-checking</code></dt> 2244 <dt><code>--disable-libphobos-checking</code></dt> 2245 <dt><code>--enable-libphobos-checking=<var>list</var></code></dt> 2246 <dd><p>This option controls whether run-time checks and contracts are compiled into 2247 the D runtime library. When the option is not specified, the library is built 2248 with ‘<samp>release</samp>’ checking. When the option is specified without a 2249 <var>list</var>, the result is the same as ‘<samp>--enable-libphobos-checking=yes</samp>’. 2250 Likewise, ‘<samp>--disable-libphobos-checking</samp>’ is equivalent to 2251 ‘<samp>--enable-libphobos-checking=no</samp>’. 2252 </p> 2253 <p>The categories of checks available in <var>list</var> are ‘<samp>yes</samp>’ (compiles 2254 libphobos with <samp>-fno-release</samp>), ‘<samp>no</samp>’ (compiles libphobos with 2255 <samp>-frelease</samp>), ‘<samp>all</samp>’ (same as ‘<samp>yes</samp>’), ‘<samp>none</samp>’ or 2256 ‘<samp>release</samp>’ (same as ‘<samp>no</samp>’). 2257 </p> 2258 <p>Individual checks available in <var>list</var> are ‘<samp>assert</samp>’ (compiles libphobos 2259 with an extra option <samp>-fassert</samp>). 2260 </p> 2261 </dd> 2262 <dt><code>--with-libphobos-druntime-only</code></dt> 2263 <dt><code>--with-libphobos-druntime-only=<var>choice</var></code></dt> 2264 <dd><p>Specify whether to build only the core D runtime library (druntime), or both 2265 the core and standard library (phobos) into libphobos. This is useful for 2266 targets that have full support in druntime, but no or incomplete support 2267 in phobos. <var>choice</var> can be one of ‘<samp>auto</samp>’, ‘<samp>yes</samp>’, and ‘<samp>no</samp>’ 2268 where ‘<samp>auto</samp>’ is the default. 2269 </p> 2270 <p>When the option is not specified, the default choice ‘<samp>auto</samp>’ means that it 2271 is inferred whether the target has support for the phobos standard library. 2272 When the option is specified without a <var>choice</var>, the result is the same as 2273 ‘<samp>--with-libphobos-druntime-only=yes</samp>’. 2274 </p> 2275 </dd> 2276 <dt><code>--with-target-system-zlib</code></dt> 2277 <dd><p>Use installed ‘<samp>zlib</samp>’ rather than that included with GCC. This needs 2278 to be available for each multilib variant, unless configured with 2279 <samp>--with-target-system-zlib=‘<samp>auto</samp>’</samp> in which case the GCC included 2280 ‘<samp>zlib</samp>’ is only used when the system installed library is not available. 2281 </p></dd> 2282 </dl> 2283 2284 <hr /> 2285 <p> 2286 <p><a href="./index.html">Return to the GCC Installation page</a> 2287 </p> 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 </body> 2299 </html> 2300
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