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GNU Info File | 1992-07-19 | 48.7 KB | 1,103 lines

This is Info file gcc.info, produced by Makeinfo-1.47 from the input file gcc.texi. This file documents the use and the internals of the GNU compiler. Copyright (C) 1988, 1989, 1992 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "GNU General Public License" and "Boycott" are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled "GNU General Public License" and "Boycott", and this permission notice, may be included in translations approved by the Free Software Foundation instead of in the original English. File: gcc.info, Node: Top, Next: Copying, Up: (DIR) Introduction ************ This manual documents how to run, install and port the GNU C compiler, as well as its new features and incompatibilities, and how to report bugs. It corresponds to GNU CC version 2.2. * Menu: * Copying:: GNU General Public License says how you can copy and share GNU CC. * Contributors:: People who have contributed to GNU CC. * Boycott:: Protect your freedom--fight "look and feel". * Invoking GCC:: Command options supported by `gcc'. * Installation:: How to configure, compile and install GNU CC. * Extensions:: GNU extensions to the C language. * Trouble:: If you have trouble installing GNU CC. * Bugs:: How, why and where to report bugs. * Service:: How to find suppliers of support for GNU CC. * VMS:: Using GNU CC on VMS. * Portability:: Goals of GNU CC's portability features. * Interface:: Function-call interface of GNU CC output. * Passes:: Order of passes, what they do, and what each file is for. * RTL:: The intermediate representation that most passes work on. * Machine Desc:: How to write machine description instruction patterns. * Target Macros:: How to write the machine description C macros. * Config:: Writing the `xm-MACHINE.h' file. * Index:: Index of concepts and symbol names. File: gcc.info, Node: Copying, Next: Contributors, Prev: Top, Up: Top GNU GENERAL PUBLIC LICENSE ************************** Version 2, June 1991 Copyright (C) 1989, 1991 Free Software Foundation, Inc. 675 Mass Ave, Cambridge, MA 02139, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble ======== The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too. When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software. Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations. Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all. The precise terms and conditions for copying, distribution and modification follow. TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 1. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you". Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does. 2. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program. You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee. 3. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions: a. You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change. b. You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License. c. If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.) These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it. Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program. In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License. 4. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following: a. Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, b. Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, c. Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.) The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable. If distribution of executable or object code is made by offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code. 5. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance. 6. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it. 7. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients' exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License. 8. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program. If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances. It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice. This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License. 9. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License. 10. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation. 11. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally. NO WARRANTY 12. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 13. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. END OF TERMS AND CONDITIONS Appendix: How to Apply These Terms to Your New Programs ======================================================= If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES. Copyright (C) 19YY NAME OF AUTHOR This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. Also add information on how to contact you by electronic and paper mail. If the program is interactive, make it output a short notice like this when it starts in an interactive mode: Gnomovision version 69, Copyright (C) 19YY NAME OF AUTHOR Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details. The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items--whatever suits your program. You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the program, if necessary. Here is a sample; alter the names: Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' (which makes passes at compilers) written by James Hacker. SIGNATURE OF TY COON, 1 April 1989 Ty Coon, President of Vice This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Library General Public License instead of this License. File: gcc.info, Node: Contributors, Next: Boycott, Prev: Copying, Up: Top Contributors to GNU CC ********************** In addition to Richard Stallman, several people have written parts of GNU CC. * The idea of using RTL and some of the optimization ideas came from the program PO written at the University of Arizona by Jack Davidson and Christopher Fraser. See "Register Allocation and Exhaustive Peephole Optimization", Software Practice and Experience 14 (9), Sept. 1984, 857-866. * Paul Rubin wrote most of the preprocessor. * Leonard Tower wrote parts of the parser, RTL generator, and RTL definitions, and of the Vax machine description. * Ted Lemon wrote parts of the RTL reader and printer. * Jim Wilson implemented loop strength reduction and some other loop optimizations. * Nobuyuki Hikichi of Software Research Associates, Tokyo, contributed the support for the Sony NEWS machine. * Charles LaBrec contributed the support for the Integrated Solutions 68020 system. * Michael Tiemann of Cygnus Support wrote the front end for C++, as well as the support for inline functions and instruction scheduling. Also the descriptions of the National Semiconductor 32000 series cpu, the SPARC cpu and part of the Motorola 88000 cpu. * Jan Stein of the Chalmers Computer Society provided support for Genix, as well as part of the 32000 machine description. * Randy Smith finished the Sun FPA support. * Robert Brown implemented the support for Encore 32000 systems. * David Kashtan of SRI adapted GNU CC to the Vomit-Making System (VMS). * Alex Crain provided changes for the 3b1. * Greg Satz and Chris Hanson assisted in making GNU CC work on HP-UX for the 9000 series 300. * William Schelter did most of the work on the Intel 80386 support. * Christopher Smith did the port for Convex machines. * Paul Petersen wrote the machine description for the Alliant FX/8. * Alain Lichnewsky ported GNU CC to the Mips cpu. * Devon Bowen, Dale Wiles and Kevin Zachmann ported GNU CC to the Tahoe. * Jonathan Stone wrote the machine description for the Pyramid computer. * Gary Miller ported GNU CC to Charles River Data Systems machines. * Richard Kenner of New York University wrote the machine descriptions for the AMD 29000, the IBM RT PC, and the IBM RS/6000 as well as the support for instruction attributes. He also made changes to better support RISC processors including changes to common subexpression elimination, strength reduction, function calling sequence handling, and condition code support, in addition to generalizing the code for frame pointer elimination. * Richard Kenner and Michael Tiemann jointly developed reorg.c, the delay slot scheduler. * Mike Meissner and Tom Wood of Data General finished the port to the Motorola 88000. * Masanobu Yuhara of Fujitsu Laboratories implemented the machine description for the Tron architecture (specifically, the Gmicro). * NeXT, Inc. donated the front end that supports the Objective C language. * James van Artsdalen wrote the code that makes efficient use of the Intel 80387 register stack. * Mike Meissner at the Open Software Foundation finished the port to the MIPS cpu, including adding ECOFF debug support. * Ron Guilmette implemented the protoize and unprotoize tools, the support for Dwarf symbolic debugging information, and much of the support for System V Release 4. He has also worked heavily on the Intel 386 and 860 support. * Torbjorn Granlund of the Swedish Institute of Computer Science implemented multiply-by-constant optimization and better long long support, and improved leaf function register allocation. File: gcc.info, Node: Boycott, Next: Invoking GCC, Prev: Contributors, Up: Top Protect Your Freedom--Fight "Look And Feel" ******************************************* This section is a political message from the League for Programming Freedom to the users of GNU CC. It is included here as an expression of support for the League on the part of the Free Software Foundation. Apple and Lotus are trying to create a new form of legal monopoly: a copyright on a class of user interfaces. These monopolies would cause serious problems for users and developers of computer software and systems. Xerox, too, has tried to make a monopoly for itself on window systems; their suit against Apple was thrown out on a technicality, but Xerox has not said anything to indicate it wouldn't try again. Until a few years ago, the law seemed clear: no one could restrict others from using a user interface; programmers were free to implement any interface they chose. Imitating interfaces, sometimes with changes, was standard practice in the computer field. The interfaces we know evolved gradually in this way; for example, the Macintosh user interface drew ideas from the Xerox interface, which in turn drew on work done at Stanford and SRI. 1-2-3 imitated VisiCalc, and dBase imitated a database program from JPL. Most computer companies, and nearly all computer users, were happy with this state of affairs. The companies that are suing say it does not offer "enough incentive" to develop their products, but they must have considered it "enough" when they made their decision to do so. It seems they are not satisfied with the opportunity to continue to compete in the marketplace--not even with a head start. If companies like Xerox, Lotus, and Apple are permitted to make law through the courts, the precedent will hobble the software industry: * Gratuitous incompatibilities will burden users. Imagine if each car manufacturer had to arrange the pedals in a different order. * Software will become and remain more expensive. Users will be "locked in" to proprietary interfaces, for which there is no real competition. * Large companies have an unfair advantage wherever lawsuits become commonplace. Since they can easily afford to sue, they can intimidate small companies with threats even when they don't really have a case. * User interface improvements will come slower, since incremental evolution through creative imitation will no longer be permitted. * Even Apple, etc., will find it harder to make improvements if they can no longer adapt the good ideas that others introduce, for fear of weakening their own legal positions. Some users suggest that this stagnation may already have started. * If you use GNU software, you might find it of some concern that user interface copyright will make it hard for the Free Software Foundation to develop programs compatible with the interfaces that you already know. To protect our freedom from lawsuits like these, a group of programmers and users have formed a new grass-roots political organization, the League for Programming Freedom. The purpose of the League is to oppose new monopolistic practices such as user-interface copyright and software patents; it calls for a return to the legal policies of the recent past, in which these practices were not allowed. The League is not concerned with free software as an issue, and not affiliated with the Free Software Foundation. The League's membership rolls include John McCarthy, inventor of Lisp, Marvin Minsky, founder of the Artificial Intelligence lab, Guy L. Steele, Jr., author of well-known books on Lisp and C, as well as Richard Stallman, the developer of GNU CC. Please join and add your name to the list. Membership dues in the League are $42 per year for programmers, managers and professionals; $10.50 for students; $21 for others. The League needs both activist members and members who only pay their dues. To join, or for more information, phone (617) 492-0023 or write to: League for Programming Freedom 1 Kendall Square #143 P.O. Box 9171 Cambridge, MA 02139 You can also send electronic mail to `league@prep.ai.mit.edu'. Here are some suggestions from the League for things you can do to protect your freedom to write programs: * Don't buy from Xerox, Lotus or Apple. Buy from their competitors or from the defendants they are suing. * Don't develop software to work with the systems made by these companies. * Port your existing software to competing systems, so that you encourage users to switch. * Write letters to company presidents to let them know their conduct is unacceptable. * Tell your friends and colleagues about this issue and how it threatens to ruin the computer industry. * Above all, don't work for the look-and-feel plaintiffs, and don't accept contracts from them. * Write to Congress to explain the importance of this issue. House Subcommittee on Intellectual Property 2137 Rayburn Bldg Washington, DC 20515 Senate Subcommittee on Patents, Trademarks and Copyrights United States Senate Washington, DC 20510 (These committees have received lots of mail already; let's give them even more.) Express your opinion! You can make a difference. File: gcc.info, Node: Invoking GCC, Next: Installation, Prev: Boycott, Up: Top GNU CC Command Options ********************** When you invoke GNU CC, it normally does preprocessing, compilation, assembly and linking. The "overall options" allow you to stop this process at an intermediate stage. For example, the `-c' option says not to run the linker. Then the output consists of object files output by the assembler. Other options are passed on to one stage of processing. Some options control the preprocessor and others the compiler itself. Yet other options control the assembler and linker; most of these are not documented here, since you rarely need to use any of them. The GNU C compiler uses a command syntax much like the Unix C compiler. The `gcc' program accepts options and file names as operands. Multiple single-letter options may *not* be grouped: `-dr' is very different from `-d -r'. You can mix options and other arguments. For the most part, the order you use doesn't matter; `gcc' reorders the command-line options so that the choices specified by option flags are applied to all input files. Order does matter when you use several options of the same kind; for example, if you specify `-L' more than once, the directories are searched in the order specified. Many options have long names starting with `-f' or with `-W'--for example, `-fforce-mem', `-fstrength-reduce', `-Wformat' and so on. Most of these have both positive and negative forms; the negative form of `-ffoo' would be `-fno-foo'. This manual documents only one of these two forms, whichever one is not the default. Here is a summary of all the options, grouped by type. Explanations are in the following sections. *Overall Options* *Note Options Controlling the Kind of Output: Overall Options. -c -S -E -o FILE -pipe -v -x LANGUAGE *Language Options* *Note Options Controlling Dialect: Dialect Options. -ansi -fbuiltin -fcond-mismatch -fno-asm -fsigned-bitfields -fsigned-char -funsigned-bitfields -funsigned-char -fwritable-strings -traditional -traditional-cpp -trigraphs *Warning Options* *Note Options to Request or Suppress Warnings: Warning Options. -fsyntax-only -pedantic -pedantic-errors -w -W -Wall -Waggregate-return -Wcast-align -Wcast-qual -Wcomment -Wconversion -Werror -Wformat -Wid-clash-LEN -Wimplicit -Wimport -Winline -Wmissing-prototypes -Wparentheses -Wpointer-arith -Wreturn-type -Wshadow -Wstrict-prototypes -Wswitch -Wtraditional -Wtrigraphs -Wuninitialized -Wunused -Wwrite-strings -Wchar-subscripts *Debugging Options* *Note Options for Debugging Your Program or GCC: Debugging Options. -a -dLETTERS -fpretend-float -g -gLEVEL -ggdb -gdwarf -gstabs -gstabs+ -gcoff -gxcoff -p -pg -save-temps *Optimization Options* *Note Options that Control Optimization: Optimize Options. -fcaller-saves -fcse-follow-jumps -fcse-skip-blocks -fdelayed-branch -fexpensive-optimizations -ffast-math -ffloat-store -fforce-addr -fforce-mem -finline -finline-functions -fkeep-inline-functions -fno-defer-pop -fno-function-cse -fomit-frame-pointer -frerun-cse-after-loop -fschedule-insns -fschedule-insns2 -fstrength-reduce -fthread-jumps -funroll-all-loops -funroll-loops -O -O2 *Preprocessor Options* *Note Options Controlling the Preprocessor: Preprocessor Options. -C -dD -dM -dN -DMACRO[=DEFN] -E -H -include FILE -imacros FILE -M -MD -MM -MMD -nostdinc -P -trigraphs -UMACRO *Linker Options* *Note Options for Linking: Link Options. OBJECT-FILE-NAME -lLIBRARY -nostdlib -static *Directory Options* *Note Options for Directory Search: Directory Options. -BPREFIX -IDIR -I- -LDIR *Target Options* *Note Target Machine and Compiler Version: Target Options. -b MACHINE -V VERSION *Machine Dependent Options* *Note Hardware Models and Configurations: Submodel Options. *M680x0 Options* -m68000 -m68020 -m68881 -mbitfield -mc68000 -mc68020 -mfpa -mnobitfield -mrtd -mshort -msoft-float *VAX Options* -mg -mgnu -munix *SPARC Options* -mforce-align -mfpu -mno-epilogue *Convex Options* -margcount -mc1 -mc2 -mnoargcount *AMD29K Options* -m29000 -m29050 -mbw -mdw -mkernel-registers -mlarge -mnbw -mnodw -msmall -mstack-check -muser-registers *M88K Options* -m88000 -m88100 -m88110 -mbig-pic -mcheck-zero-division -mhandle-large-shift -midentify-revision -mno-check-zero-division -mno-ocs-debug-info -mno-ocs-frame-position -mno-optimize-arg-area -mno-underscores -mocs-debug-info -mocs-frame-position -moptimize-arg-area -mshort-data-NUM -msvr3 -msvr4 -mtrap-large-shift -muse-div-instruction -mversion-03.00 -mwarn-passed-structs *RS/6000 Options* -mfp-in-toc -mno-fop-in-toc *RT Options* -mcall-lib-mul -mfp-arg-in-fpregs -mfp-arg-in-gregs -mfull-fp-blocks -mhc-struct-return -min-line-mul -mminimum-fp-blocks -mnohc-struct-return *MIPS Options* -mcpu=CPU TYPE -mips2 -mips3 -mint64 -mlong64 -mlonglong128 -mmips-as -mgas -mrnames -mno-rnames -mgpopt -mno-gpopt -mstats -mno-stats -mmemcpy -mno-memcpy -mno-mips-tfile -mmips-tfile -msoft-float -mhard-float -mabicalls -mno-abicalls -mhalf-pic -mno-half-pic -G NUM -nocpp *i386 Options* -m486 -msoft-float *Code Generation Options* *Note Options for Code Generation Conventions: Code Gen Options. -fcall-saved-REG -fcall-used-REG -ffixed-REG -fno-common -fpcc-struct-return -fpic -fPIC -fshared-data -fshort-enums -fshort-double -fvolatile * Menu: * Overall Options:: Controlling the kind of output: an executable, object files, assembler files, or preprocessed source. * Dialect Options:: Controlling the variant of C language compiled. * Warning Options:: How picky should the compiler be? * Debugging Options:: Symbol tables, measurements, and debugging dumps. * Optimize Options:: How much optimization? * Preprocessor Options:: Controlling header files and macro definitions. Also, getting dependency information for Make. * Link Options:: Specifying libraries and so on. * Directory Options:: Where to find header files and libraries. Where to find the compiler executable files. * Target Options:: Running a cross-compiler, or an old version of GNU CC. * Submodel Options:: Specifying minor hardware or convention variations, such as 68010 vs 68020. * Code Gen Options:: Specifying conventions for function calls, data layout and register usage. * Environment Variables:: Env vars that affect GNU CC. File: gcc.info, Node: Overall Options, Next: Dialect Options, Prev: Invoking GCC, Up: Invoking GCC Options Controlling the Kind of Output ====================================== Compilation can involve up to four stages: preprocessing, compilation proper, assembly and linking, always in that order. The first three stages apply to an individual source file, and end by producing an object file; linking combines all the object files (those newly compiled, and those specified as input) into an executable file. For any given input file, the file name suffix determines what kind of compilation is done: `FILE.c' C source code which must be preprocessed. `FILE.i' C source code which should not be preprocessed. `FILE.m' Objective-C source code `FILE.h' C header file (not to be compiled or linked). `FILE.cc' `FILE.cxx' `FILE.C' C++ source code which must be preprocessed. `FILE.s' Assembler code. `FILE.S' Assembler code which must be preprocessed. `OTHER' An object file to be fed straight into linking. Any file name with no recognized suffix is treated this way. You can specify the input language explicitly with the `-x' option: `-x LANGUAGE' Specify explicitly the LANGUAGE for the following input files (rather than choosing a default based on the file name suffix). This option applies to all following input files until the next `-x' option. Possible values of LANGUAGE are `c', `objective-c', `c-header', `c++', `cpp-output', `assembler', and `assembler-with-cpp'. `-x none' Turn off any specification of a language, so that subsequent files are handled according to their file name suffixes (as they are if `-x' has not been used at all). If you only want some of the stages of compilation, you can use `-x' (or filename suffixes) to tell `gcc' where to start, and one of the options `-c', `-S', or `-E' to say where `gcc' is to stop. Note that some combinations (for example, `-x cpp-output -E' instruct `gcc' to do nothing at all. `-c' Compile or assemble the source files, but do not link. The linking stage simply is not done. The ultimate output is in the form of an object file for each source file. By default, the object file name for a source file is made by replacing the suffix `.c', `.i', `.s', etc., with `.o'. Unrecognized input files, not requiring compilation or assembly, are ignored. `-S' Stop after the stage of compilation proper; do not assemble. The output is in the form of an assembler code file for each non-assembler input file specified. By default, the assembler file name for a source file is made by replacing the suffix `.c', `.i', etc., with `.s'. Input files that don't require compilation are ignored. `-E' Stop after the preprocessing stage; do not run the compiler proper. The output is in the form of preprocessed source code, which is sent to the standard output. Input files which don't require preprocessing are ignored. `-o FILE' Place output in file FILE. This applies regardless to whatever sort of output is being produced, whether it be an executable file, an object file, an assembler file or preprocessed C code. Since only one output file can be specified, it does not make sense to use `-o' when compiling more than one input file, unless you are producing an executable file as output. If `-o' is not specified, the default is to put an executable file in `a.out', the object file for `SOURCE.SUFFIX' in `SOURCE.o', its assembler file in `SOURCE.s', and all preprocessed C source on standard output. `-v' Print (on standard error output) the commands executed to run the stages of compilation. Also print the version number of the compiler driver program and of the preprocessor and the compiler proper. `-pipe' Use pipes rather than temporary files for communication between the various stages of compilation. This fails to work on some systems where the assembler is unable to read from a pipe; but the GNU assembler has no trouble. File: gcc.info, Node: Dialect Options, Next: Warning Options, Prev: Overall Options, Up: Invoking GCC Options Controlling Dialect =========================== The following options control the dialect of C that the compiler accepts: `-ansi' Support all ANSI standard C programs. This turns off certain features of GNU C that are incompatible with ANSI C, such as the `asm', `inline' and `typeof' keywords, and predefined macros such as `unix' and `vax' that identify the type of system you are using. It also enables the undesirable and rarely used ANSI trigraph feature, and disallows `$' as part of identifiers. The alternate keywords `__asm__', `__extension__', `__inline__' and `__typeof__' continue to work despite `-ansi'. You would not want to use them in an ANSI C program, of course, but it useful to put them in header files that might be included in compilations done with `-ansi'. Alternate predefined macros such as `__unix__' and `__vax__' are also available, with or without `-ansi'. The `-ansi' option does not cause non-ANSI programs to be rejected gratuitously. For that, `-pedantic' is required in addition to `-ansi'. *Note Warning Options::. The macro `__STRICT_ANSI__' is predefined when the `-ansi' option is used. Some header files may notice this macro and refrain from declaring certain functions or defining certain macros that the ANSI standard doesn't call for; this is to avoid interfering with any programs that might use these names for other things. The functions `alloca', `abort', `exit', and `_exit' are not builtin functions when `-ansi' is used. `-fno-asm' Do not recognize `asm', `inline' or `typeof' as a keyword. These words may then be used as identifiers. You can use `__asm__', `__inline__' and `__typeof__' instead. `-ansi' implies `-fno-asm'. `-fno-builtin' Don't recognize built-in functions that do not begin with two leading underscores. Currently, the functions affected include `alloca', `abort', `exit', `_exit', `abs', `fabs', `labs', `memcpy', `memcmp', `strcmp', `strcpy', `strlen', and `sqrt'. The `-ansi' option prevents `alloca' and `_exit' from being builtin functions. `-trigraphs' Support ANSI C trigraphs. You don't want to know about this brain-damage. The `-ansi' option implies `-trigraphs'. `-traditional' Attempt to support some aspects of traditional C compilers. Specifically: * All `extern' declarations take effect globally even if they are written inside of a function definition. This includes implicit declarations of functions. * The keywords `typeof', `inline', `signed', `const' and `volatile' are not recognized. (You can still use the alternative keywords such as `__typeof__', `__inline__', and so on.) * Comparisons between pointers and integers are always allowed. * Integer types `unsigned short' and `unsigned char' promote to `unsigned int'. * Out-of-range floating point literals are not an error. * String "constants" are not necessarily constant; they are stored in writable space, and identical looking constants are allocated separately. (This is the same as the effect of `-fwritable-strings'.) * All automatic variables not declared `register' are preserved by `longjmp'. Ordinarily, GNU C follows ANSI C: automatic variables not declared `volatile' may be clobbered. * In the preprocessor, comments convert to nothing at all, rather than to a space. This allows traditional token concatenation. * In the preprocessor, macro arguments are recognized within string constants in a macro definition (and their values are stringified, though without additional quote marks, when they appear in such a context). The preprocessor always considers a string constant to end at a newline. * The predefined macro `__STDC__' is not defined when you use `-traditional', but `__GNUC__' is (since the GNU extensions which `__GNUC__' indicates are not affected by `-traditional'). If you need to write header files that work differently depending on whether `-traditional' is in use, by testing both of these predefined macros you can distinguish four situations: GNU C, traditional GNU C, other ANSI C compilers, and other old C compilers. You may wish to use `-fno-builtin' as well as `-traditional' if your program uses names that are normally GNU C builtin functions for other purposes of its own. `-traditional-cpp' Attempt to support some aspects of traditional C preprocessors. This includes the last three items in the table immediately above, but none of the other effects of `-traditional'. `-fcond-mismatch' Allow conditional expressions with mismatched types in the second and third arguments. The value of such an expression is void. `-funsigned-char' Let the type `char' be unsigned, like `unsigned char'. Each kind of machine has a default for what `char' should be. It is either like `unsigned char' by default or like `signed char' by default. Ideally, a portable program should always use `signed char' or `unsigned char' when it depends on the signedness of an object. But many programs have been written to use plain `char' and expect it to be signed, or expect it to be unsigned, depending on the machines they were written for. This option, and its inverse, let you make such a program work with the opposite default. The type `char' is always a distinct type from each of `signed char' or `unsigned char', even though its behavior is always just like one of those two. `-fsigned-char' Let the type `char' be signed, like `signed char'. Note that this is equivalent to `-fno-unsigned-char', which is the negative form of `-funsigned-char'. Likewise, `-fno-signed-char' is equivalent to `-funsigned-char'. `-fsigned-bitfields' `-funsigned-bitfields' `-fno-signed-bitfields' `-fno-unsigned-bitfields' These options control whether a bitfield is signed or unsigned, when the declaration does not use either `signed' or `unsigned'. By default, such a bitfield is signed, because this is consistent: the basic integer types such as `int' are signed types. However, when `-traditional' is used, bitfields are all unsigned no matter what. `-fwritable-strings' Store string constants in the writable data segment and don't uniquize them. This is for compatibility with old programs which assume they can write into string constants. `-traditional' also has this effect. Writing into string constants is a very bad idea; "constants" should be constant.