\input texinfo @c -*-texinfo-*-
@c %**start of header
@setfilename gcc.info
-@c @setfilename usegcc.info
-@c @setfilename portgcc.info
-@c To produce the full manual, use the "gcc.info" setfilename, and
-@c make sure the following do NOT begin with '@c' (and the @clear lines DO)
-@set INTERNALS
-@set USING
-@c To produce a user-only manual, use the "usegcc.info" setfilename, and
-@c make sure the following does NOT begin with '@c':
-@c @clear INTERNALS
-@c To produce a porter-only manual, use the "portgcc.info" setfilename,
-@c and make sure the following does NOT begin with '@c':
-@c @clear USING
-
-@c (For FSF printing, turn on smallbook, comment out finalout below;
-@c that is all that is needed.)
-
-@c 6/27/96 FSF DO wants smallbook fmt for 1st bound edition.
-@c @smallbook
-
-@c i also commented out the finalout command, so if there *are* any
-@c overfulls, you'll (hopefully) see the rectangle in the right hand
-@c margin. -mew 15june93
-@c @finalout
+@c INTERNALS is used by md.texi to determine whether to include the
+@c whole of that file, in the internals manual, or only the part
+@c dealing with constraints, in the user manual.
+@clear INTERNALS
@c NOTE: checks/things to do:
@c
@c
@c anything else? --mew 10feb93
-@c For consistency, use the following:
-@c - "back end" as a noun, "back-end" as an adjective.
-@c - "bit-field" not "bitfield" or "bit field" (following the C and C++
-@c standards).
-@c - "built-in" as an adjective ("built-in function"), or sometimes
-@c "built in", not "builtin" (which isn't a word).
-@c - "front end" as a noun, "front-end" as an adjective.
-@c - "GCC" for the GNU Compiler Collection, both generally
-@c and as the GNU C Compiler in the context of compiling C;
-@c "G++" for the C++ compiler; "gcc" and "g++" (lowercase),
-@c marked up with @command, for the commands for compilation when the
-@c emphasis is on those; "GNU C" and "GNU C++" for language dialects;
-@c and try to avoid the older term "GNU CC".
-
-@macro gcctabopt{body}
-@code{\body\}
-@end macro
-@macro gccoptlist{body}
-@smallexample
-\body\
-@end smallexample
-@end macro
-@c Makeinfo handles the above macro OK, TeX needs manual line breaks;
-@c they get lost at some point in handling the macro. But if @macro is
-@c used here rather than @alias, it produces double line breaks.
-@iftex
-@alias gol = *
-@end iftex
-@ifnottex
-@macro gol
-@end macro
-@end ifnottex
+@include gcc-common.texi
-@ifset INTERNALS
-@ifset USING
-@settitle Using and Porting the GNU Compiler Collection (GCC)
-@end ifset
-@end ifset
-@c seems reasonable to assume at least one of INTERNALS or USING is set...
-@ifclear INTERNALS
-@settitle Using the GNU Compiler Collection
-@end ifclear
-@ifclear USING
-@settitle Porting the GNU Compiler Collection
-@end ifclear
+@settitle Using the GNU Compiler Collection (GCC)
@c Create a separate index for command line options.
@defcodeindex op
@syncodeindex pg cp
@syncodeindex tp cp
-@c %**end of header
-
-@c Use with @@smallbook.
+@paragraphindent 1
-@c Cause even numbered pages to be printed on the left hand side of
-@c the page and odd numbered pages to be printed on the right hand
-@c side of the page. Using this, you can print on both sides of a
-@c sheet of paper and have the text on the same part of the sheet.
-
-@c The text on right hand pages is pushed towards the right hand
-@c margin and the text on left hand pages is pushed toward the left
-@c hand margin.
-@c (To provide the reverse effect, set bindingoffset to -0.75in.)
-
-@c @tex
-@c \global\bindingoffset=0.75in
-@c \global\normaloffset =0.75in
-@c @end tex
+@c %**end of header
-@c Change the font used for @def... commands, since the default
-@c proportional one used is bad for names starting __.
-@tex
-\global\setfont\defbf\ttbshape{10}{\magstep1}
-@end tex
+@copying
+Copyright @copyright{} 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
+1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
+2008 Free Software Foundation, Inc.
-@ifnottex
-@dircategory Programming
-@direntry
-* gcc: (gcc). The GNU Compiler Collection.
-@end direntry
-@ifset INTERNALS
-@ifset USING
-This file documents the use and the internals of the GNU compiler.
-@end ifset
-@end ifset
-@ifclear USING
-This file documents the internals of the GNU compiler.
-@end ifclear
-@ifclear INTERNALS
-This file documents the use of the GNU compiler.
-@end ifclear
-@sp 1
-Published by the Free Software Foundation@*
-59 Temple Place - Suite 330@*
-Boston, MA 02111-1307 USA
-@sp 1
-@c When you update the list of years below, search for copyright{} and
-@c update the other copy too.
-Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001 Free Software Foundation, Inc.
-@sp 1
Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
+under the terms of the GNU Free Documentation License, Version 1.2 or
any later version published by the Free Software Foundation; with the
Invariant Sections being ``GNU General Public License'' and ``Funding
Free Software'', the Front-Cover texts being (a) (see below), and with
You have freedom to copy and modify this GNU Manual, like GNU
software. Copies published by the Free Software Foundation raise
funds for GNU development.
+@end copying
+@ifnottex
+@dircategory Software development
+@direntry
+* gcc: (gcc). The GNU Compiler Collection.
+* g++: (gcc). The GNU C++ compiler.
+@end direntry
+This file documents the use of the GNU compilers.
+@sp 1
+@insertcopying
+@sp 1
@end ifnottex
@setchapternewpage odd
-@c @finalout
@titlepage
-@ifset INTERNALS
-@ifset USING
-@center @titlefont{Using and Porting the GNU Compiler Collection}
-
-@end ifset
-@end ifset
-@ifclear INTERNALS
@title Using the GNU Compiler Collection
-@end ifclear
-@ifclear USING
-@title Porting the GNU Compiler Collection
-@end ifclear
-@sp 2
-@center Richard M. Stallman
-@sp 3
-@center Last updated 22 June 2001
-@sp 1
-@c The version number appears five times more in this file.
-
-@center for GCC 3.1
+@versionsubtitle
+@author Richard M. Stallman and the @sc{GCC} Developer Community
@page
@vskip 0pt plus 1filll
-Copyright @copyright{} 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1998,
-1999, 2000, 2001 Free Software Foundation, Inc.
+Published by:
+@multitable @columnfractions 0.5 0.5
+@item GNU Press
+@tab Website: www.gnupress.org
+@item a division of the
+@tab General: @tex press@@gnu.org @end tex
+@item Free Software Foundation
+@tab Orders: @tex sales@@gnu.org @end tex
+@item 51 Franklin Street, Fifth Floor
+@tab Tel 617-542-5942
+@item Boston, MA 02110-1301 USA
+@tab Fax 617-542-2652
+@end multitable
@sp 2
-For GCC Version 3.1@*
-@sp 1
-Published by the Free Software Foundation @*
-59 Temple Place---Suite 330@*
-Boston, MA 02111-1307, USA@*
-Last printed April, 1998.@*
-Printed copies are available for $50 each.@*
-ISBN 1-882114-37-X
-@sp 1
-Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being ``GNU General Public License'', the Front-Cover
-texts being (a) (see below), and with the Back-Cover Texts being (b)
-(see below). A copy of the license is included in the section entitled
-``GNU Free Documentation License''.
-
-(a) The FSF's Front-Cover Text is:
-
- A GNU Manual
+@ifset FSFPRINT
+@c Update this ISBN when printing a new edition.
+@acronym{ISBN} 1-882114-39-6
-(b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
- software. Copies published by the Free Software Foundation raise
- funds for GNU development.
+Cover art by Gary M. Torrisi. Cover design by Jonathan Richard.
+@end ifset
+@ifclear FSFPRINT
+Last printed October 2003 for GCC 3.3.1.@*
+Printed copies are available for $45 each.
+@end ifclear
+@sp 1
+@insertcopying
@end titlepage
@summarycontents
@contents
@top Introduction
@cindex introduction
-@ifset INTERNALS
-@ifset USING
-This manual documents how to run, install and port the GNU
-compiler, as well as its new features and incompatibilities, and how to
-report bugs. It corresponds to GCC version 3.1.
+This manual documents how to use the GNU compilers,
+as well as their features and incompatibilities, and how to report
+bugs. It corresponds to the compilers
+@ifset VERSION_PACKAGE
+@value{VERSION_PACKAGE}
@end ifset
-@end ifset
-
-@ifclear INTERNALS
-This manual documents how to run and install the GNU compiler,
-as well as its new features and incompatibilities, and how to report
-bugs. It corresponds to GCC version 3.1.
-@end ifclear
-@ifclear USING
-This manual documents how to port the GNU compiler,
-as well as its new features and incompatibilities, and how to report
-bugs. It corresponds to GCC version 3.1.
-@end ifclear
+version @value{version-GCC}.
+The internals of the GNU compilers, including how to port them to new
+targets and some information about how to write front ends for new
+languages, are documented in a separate manual. @xref{Top,,
+Introduction, gccint, GNU Compiler Collection (GCC) Internals}.
@menu
-@ifset USING
* G++ and GCC:: You can compile C or C++ programs.
* Standards:: Language standards supported by GCC.
* Invoking GCC:: Command options supported by @samp{gcc}.
-* Installation:: How to configure, compile and install GCC.
+* C Implementation:: How GCC implements the ISO C specification.
* C Extensions:: GNU extensions to the C language family.
* C++ Extensions:: GNU extensions to the C++ language.
* Objective-C:: GNU Objective-C runtime features.
-* Gcov:: gcov: a GCC test coverage program.
-* Trouble:: If you have trouble installing GCC.
+* Compatibility:: Binary Compatibility
+* Gcov:: @command{gcov}---a test coverage program.
+* Trouble:: If you have trouble using GCC.
* Bugs:: How, why and where to report bugs.
* Service:: How to find suppliers of support for GCC.
* Contributing:: How to contribute to testing and developing GCC.
-* VMS:: Using GCC on VMS.
-* Makefile:: List of Makefile targets.
-@end ifset
-@ifset INTERNALS
-* Portability:: Goals of GCC's portability features.
-* Interface:: Function-call interface of GCC output.
-* Passes:: Order of passes, what they do, and what each file is for.
-* Trees:: The source representation used by the C and C++ front ends.
-* 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 and functions.
-* Config:: Writing the @file{xm-@var{machine}.h} file.
-* Fragments:: Writing the @file{t-@var{target}} and @file{x-@var{host}} files.
-@end ifset
* Funding:: How to help assure funding for free software.
-* GNU/Linux:: Linux and the GNU Project
+* GNU Project:: The GNU Project and GNU/Linux.
* Copying:: GNU General Public License says
how you can copy and share GCC.
* Contributors:: People who have contributed to GCC.
* Option Index:: Index to command line options.
-* Index:: Index of concepts and symbol names.
+* Keyword Index:: Index of concepts and symbol names.
@end menu
-@ifset USING
-@node G++ and GCC
-@chapter Compile C, C++, Objective-C, Fortran, Java or CHILL
-
-@cindex Objective-C
-@cindex Fortran
-@cindex Java
-@cindex CHILL
-Several versions of the compiler (C, C++, Objective-C, Fortran, Java
-and CHILL) are integrated; this is why we use the name
-``GNU Compiler Collection''. GCC can compile programs written in any of these
-languages. The Fortran, CHILL, and Java compilers are described in
-separate manuals.
-
-@cindex GCC
-``GCC'' is a common shorthand term for the GNU Compiler Collection. This is both
-the most general name for the compiler, and the name used when the
-emphasis is on compiling C programs (as the abbreviation formerly
-stood for ``GNU C Compiler'').
-
-@cindex C++
-@cindex G++
-When referring to C++ compilation, it is usual to call the compiler
-``G++''. Since there is only one compiler, it is also accurate to call
-it ``GCC'' no matter what the language context; however, the term
-``G++'' is more useful when the emphasis is on compiling C++ programs.
-
-We use the name ``GCC'' to refer to the compilation system as a
-whole, and more specifically to the language-independent part of the
-compiler. For example, we refer to the optimization options as
-affecting the behavior of ``GCC'' or sometimes just ``the compiler''.
-
-Front ends for other languages, such as Ada 95 and Pascal exist but
-have not yet been integrated into GCC@. These front ends, like that for C++,
-are built in subdirectories of GCC and link to it. The result is an
-integrated compiler that can compile programs written in C, C++,
-Objective-C, or any of the languages for which you have installed front
-ends.
-
-In this manual, we only discuss the options for the C, Objective-C, and
-C++ compilers and those of the GCC core. Consult the documentation
-of the other front ends for the options to use when compiling programs
-written in other languages.
-
-@cindex compiler compared to C++ preprocessor
-@cindex intermediate C version, nonexistent
-@cindex C intermediate output, nonexistent
-G++ is a @emph{compiler}, not merely a preprocessor. G++ builds object
-code directly from your C++ program source. There is no intermediate C
-version of the program. (By contrast, for example, some other
-implementations use a program that generates a C program from your C++
-source.) Avoiding an intermediate C representation of the program means
-that you get better object code, and better debugging information. The
-GNU debugger, GDB, works with this information in the object code to
-give you comprehensive C++ source-level editing capabilities
-(@pxref{C,,C and C++,gdb.info, Debugging with GDB}).
-
-@c FIXME! Someone who knows something about Objective-C ought to put in
-@c a paragraph or two about it here, and move the index entry down when
-@c there is more to point to than the general mention in the 1st par.
-
-@node Standards
-@chapter Language Standards Supported by GCC
-@cindex C standard
-@cindex C standards
-@cindex ANSI C standard
-@cindex ANSI C
-@cindex ANSI C89
-@cindex C89
-@cindex ANSI X3.159-1989
-@cindex X3.159-1989
-@cindex ISO C standard
-@cindex ISO C
-@cindex ISO C89
-@cindex ISO C90
-@cindex ISO/IEC 9899
-@cindex ISO 9899
-@cindex C90
-@cindex ISO C94
-@cindex C94
-@cindex ISO C95
-@cindex C95
-@cindex ISO C99
-@cindex C99
-@cindex ISO C9X
-@cindex C9X
-@cindex Technical Corrigenda
-@cindex TC1
-@cindex Technical Corrigendum 1
-@cindex TC2
-@cindex Technical Corrigendum 2
-@cindex AMD1
-@cindex freestanding implementation
-@cindex freestanding environment
-@cindex hosted implementation
-@cindex hosted environment
-@findex __STDC_HOSTED__
-
-For each language compiled by GCC for which there is a standard, GCC
-attempts to follow one or more versions of that standard, possibly
-with some exceptions, and possibly with some extensions.
-
-GCC supports three versions of the C standard, although support for
-the most recent version is not yet complete.
-
-@opindex std
-@opindex ansi
-@opindex pedantic
-@opindex pedantic-errors
-The original ANSI C standard (X3.159-1989) was ratified in 1989 and
-published in 1990. This standard was ratified as an ISO standard
-(ISO/IEC 9899:1990) later in 1990. There were no technical
-differences between these publications, although the sections of the
-ANSI standard were renumbered and became clauses in the ISO standard.
-This standard, in both its forms, is commonly known as @dfn{C89}, or
-occasionally as @dfn{C90}, from the dates of ratification. The ANSI
-standard, but not the ISO standard, also came with a Rationale
-document. To select this standard in GCC, use one of the options
-@option{-ansi}, @option{-std=c89} or @option{-std=iso9899:1990}; to obtain
-all the diagnostics required by the standard, you should also specify
-@option{-pedantic} (or @option{-pedantic-errors} if you want them to be
-errors rather than warnings). @xref{C Dialect Options,,Options
-Controlling C Dialect}.
-
-Errors in the 1990 ISO C standard were corrected in two Technical
-Corrigenda published in 1994 and 1996. GCC does not support the
-uncorrected version.
-
-An amendment to the 1990 standard was published in 1995. This
-amendment added digraphs and @code{__STDC_VERSION__} to the language,
-but otherwise concerned the library. This amendment is commonly known
-as @dfn{AMD1}; the amended standard is sometimes known as @dfn{C94} or
-@dfn{C95}. To select this standard in GCC, use the option
-@option{-std=iso9899:199409} (with, as for other standard versions,
-@option{-pedantic} to receive all required diagnostics).
-
-A new edition of the ISO C standard was published in 1999 as ISO/IEC
-9899:1999, and is commonly known as @dfn{C99}. GCC has incomplete
-support for this standard version; see
-@uref{http://gcc.gnu.org/c99status.html} for details. To select this
-standard, use @option{-std=c99} or @option{-std=iso9899:1999}. (While in
-development, drafts of this standard version were referred to as
-@dfn{C9X}.)
-
-@opindex traditional
-GCC also has some limited support for traditional (pre-ISO) C with the
-@option{-traditional} option. This support may be of use for compiling
-some very old programs that have not been updated to ISO C, but should
-not be used for new programs. It will not work with some modern C
-libraries such as the GNU C library.
-
-By default, GCC provides some extensions to the C language that on
-rare occasions conflict with the C standard. @xref{C
-Extensions,,Extensions to the C Language Family}. Use of the
-@option{-std} options listed above will disable these extensions where
-they conflict with the C standard version selected. You may also
-select an extended version of the C language explicitly with
-@option{-std=gnu89} (for C89 with GNU extensions) or @option{-std=gnu99}
-(for C99 with GNU extensions). The default, if no C language dialect
-options are given, is @option{-std=gnu89}; this will change to
-@option{-std=gnu99} in some future release when the C99 support is
-complete. Some features that are part of the C99 standard are
-accepted as extensions in C89 mode.
-
-The ISO C standard defines (in clause 4) two classes of conforming
-implementation. A @dfn{conforming hosted implementation} supports the
-whole standard including all the library facilities; a @dfn{conforming
-freestanding implementation} is only required to provide certain
-library facilities: those in @code{<float.h>}, @code{<limits.h>},
-@code{<stdarg.h>}, and @code{<stddef.h>}; since AMD1, also those in
-@code{<iso646.h>}; and in C99, also those in @code{<stdbool.h>} and
-@code{<stdint.h>}. In addition, complex types, added in C99, are not
-required for freestanding implementations. The standard also defines
-two environments for programs, a @dfn{freestanding environment},
-required of all implementations and which may not have library
-facilities beyond those required of freestanding implementations,
-where the handling of program startup and termination are
-implementation-defined, and a @dfn{hosted environment}, which is not
-required, in which all the library facilities are provided and startup
-is through a function @code{int main (void)} or @code{int main (int,
-char *[])}. An OS kernel would be a freestanding environment; a
-program using the facilities of an operating system would normally be
-in a hosted implementation.
-
-@opindex ffreestanding
-GCC aims towards being usable as a conforming freestanding
-implementation, or as the compiler for a conforming hosted
-implementation. By default, it will act as the compiler for a hosted
-implementation, defining @code{__STDC_HOSTED__} as @code{1} and
-presuming that when the names of ISO C functions are used, they have
-the semantics defined in the standard. To make it act as a conforming
-freestanding implementation for a freestanding environment, use the
-option @option{-ffreestanding}; it will then define
-@code{__STDC_HOSTED__} to @code{0} and not make assumptions about the
-meanings of function names from the standard library. To build an OS
-kernel, you may well still need to make your own arrangements for
-linking and startup. @xref{C Dialect Options,,Options Controlling C
-Dialect}.
-
-GCC does not provide the library facilities required only of hosted
-implementations, nor yet all the facilities required by C99 of
-freestanding implementations; to use the facilities of a hosted
-environment, you will need to find them elsewhere (for example, in the
-GNU C library). @xref{Standard Libraries,,Standard Libraries}.
-
-For references to Technical Corrigenda, Rationale documents and
-information concerning the history of C that is available online, see
-@uref{http://gcc.gnu.org/readings.html}
-
-@c FIXME: details of C++ standard.
-
-There is no formal written standard for Objective-C@. The most
-authoritative manual is ``Object-Oriented Programming and the
-Objective-C Language'', available at a number of web sites;
-@uref{http://developer.apple.com/techpubs/macosx/Cocoa/ObjectiveC/} has a
-recent version, while @uref{http://www.toodarkpark.org/computers/objc/}
-is an older example. @uref{http://www.gnustep.org} includes useful
-information as well.
-
-@xref{Language,,The GNU Fortran Language, g77, Using and Porting GNU
-Fortran}, for details of the Fortran language supported by GCC@.
-
-@xref{Compatibility,,Compatibility with the Java Platform, gcj, GNU gcj},
-for details of compatibility between @code{gcj} and the Java Platform.
-
-@xref{References,,Language Definition References, chill, GNU Chill},
-for details of the CHILL standard.
-
+@include frontends.texi
+@include standards.texi
@include invoke.texi
-
-@include install-old.texi
-
+@include implement-c.texi
@include extend.texi
-
@include objc.texi
-
+@include compat.texi
@include gcov.texi
-
-@node Trouble
-@chapter Known Causes of Trouble with GCC
-@cindex bugs, known
-@cindex installation trouble
-@cindex known causes of trouble
-
-This section describes known problems that affect users of GCC@. Most
-of these are not GCC bugs per se---if they were, we would fix them.
-But the result for a user may be like the result of a bug.
-
-Some of these problems are due to bugs in other software, some are
-missing features that are too much work to add, and some are places
-where people's opinions differ as to what is best.
-
-@menu
-* Actual Bugs:: Bugs we will fix later.
-* Cross-Compiler Problems:: Common problems of cross compiling with GCC.
-* Interoperation:: Problems using GCC with other compilers,
- and with certain linkers, assemblers and debuggers.
-* External Bugs:: Problems compiling certain programs.
-* Incompatibilities:: GCC is incompatible with traditional C.
-* Fixed Headers:: GCC uses corrected versions of system header files.
- This is necessary, but doesn't always work smoothly.
-* Standard Libraries:: GCC uses the system C library, which might not be
- compliant with the ISO C standard.
-* Disappointments:: Regrettable things we can't change, but not quite bugs.
-* C++ Misunderstandings:: Common misunderstandings with GNU C++.
-* Protoize Caveats:: Things to watch out for when using @code{protoize}.
-* Non-bugs:: Things we think are right, but some others disagree.
-* Warnings and Errors:: Which problems in your code get warnings,
- and which get errors.
-@end menu
-
-@node Actual Bugs
-@section Actual Bugs We Haven't Fixed Yet
-
-@itemize @bullet
-@item
-The @code{fixincludes} script interacts badly with automounters; if the
-directory of system header files is automounted, it tends to be
-unmounted while @code{fixincludes} is running. This would seem to be a
-bug in the automounter. We don't know any good way to work around it.
-
-@item
-The @code{fixproto} script will sometimes add prototypes for the
-@code{sigsetjmp} and @code{siglongjmp} functions that reference the
-@code{jmp_buf} type before that type is defined. To work around this,
-edit the offending file and place the typedef in front of the
-prototypes.
-
-@item
-@opindex pedantic-errors
-When @option{-pedantic-errors} is specified, GCC will incorrectly give
-an error message when a function name is specified in an expression
-involving the comma operator.
-@end itemize
-
-@node Cross-Compiler Problems
-@section Cross-Compiler Problems
-
-You may run into problems with cross compilation on certain machines,
-for several reasons.
-
-@itemize @bullet
-@item
-Cross compilation can run into trouble for certain machines because
-some target machines' assemblers require floating point numbers to be
-written as @emph{integer} constants in certain contexts.
-
-The compiler writes these integer constants by examining the floating
-point value as an integer and printing that integer, because this is
-simple to write and independent of the details of the floating point
-representation. But this does not work if the compiler is running on
-a different machine with an incompatible floating point format, or
-even a different byte-ordering.
-
-In addition, correct constant folding of floating point values
-requires representing them in the target machine's format.
-(The C standard does not quite require this, but in practice
-it is the only way to win.)
-
-It is now possible to overcome these problems by defining macros such
-as @code{REAL_VALUE_TYPE}. But doing so is a substantial amount of
-work for each target machine.
-@ifset INTERNALS
-@xref{Cross-compilation}.
-@end ifset
-@ifclear INTERNALS
-@xref{Cross-compilation,,Cross Compilation and Floating Point Format,
-gcc.info, Using and Porting GCC}.
-@end ifclear
-
-@item
-At present, the program @file{mips-tfile} which adds debug
-support to object files on MIPS systems does not work in a cross
-compile environment.
-@end itemize
-
-@node Interoperation
-@section Interoperation
-
-This section lists various difficulties encountered in using GCC
-together with other compilers or with the assemblers, linkers,
-libraries and debuggers on certain systems.
-
-@itemize @bullet
-@item
-Objective-C does not work on the RS/6000.
-
-@item
-G++ does not do name mangling in the same way as other C++
-compilers. This means that object files compiled with one compiler
-cannot be used with another.
-
-This effect is intentional, to protect you from more subtle problems.
-Compilers differ as to many internal details of C++ implementation,
-including: how class instances are laid out, how multiple inheritance is
-implemented, and how virtual function calls are handled. If the name
-encoding were made the same, your programs would link against libraries
-provided from other compilers---but the programs would then crash when
-run. Incompatible libraries are then detected at link time, rather than
-at run time.
-
-@item
-Older GDB versions sometimes fail to read the output of GCC version
-2. If you have trouble, get GDB version 4.4 or later.
-
-@item
-@cindex DBX
-DBX rejects some files produced by GCC, though it accepts similar
-constructs in output from PCC@. Until someone can supply a coherent
-description of what is valid DBX input and what is not, there is
-nothing I can do about these problems. You are on your own.
-
-@item
-The GNU assembler (GAS) does not support PIC@. To generate PIC code, you
-must use some other assembler, such as @file{/bin/as}.
-
-@item
-On some BSD systems, including some versions of Ultrix, use of profiling
-causes static variable destructors (currently used only in C++) not to
-be run.
-
-@ignore
-@cindex @code{vfork}, for the Sun-4
-@item
-There is a bug in @code{vfork} on the Sun-4 which causes the registers
-of the child process to clobber those of the parent. Because of this,
-programs that call @code{vfork} are likely to lose when compiled
-optimized with GCC when the child code alters registers which contain
-C variables in the parent. This affects variables which are live in the
-parent across the call to @code{vfork}.
-
-If you encounter this, you can work around the problem by declaring
-variables @code{volatile} in the function that calls @code{vfork}, until
-the problem goes away, or by not declaring them @code{register} and not
-using @option{-O} for those source files.
-@end ignore
-
-@item
-On some SGI systems, when you use @option{-lgl_s} as an option,
-it gets translated magically to @samp{-lgl_s -lX11_s -lc_s}.
-Naturally, this does not happen when you use GCC@.
-You must specify all three options explicitly.
-
-@item
-On a Sparc, GCC aligns all values of type @code{double} on an 8-byte
-boundary, and it expects every @code{double} to be so aligned. The Sun
-compiler usually gives @code{double} values 8-byte alignment, with one
-exception: function arguments of type @code{double} may not be aligned.
-
-As a result, if a function compiled with Sun CC takes the address of an
-argument of type @code{double} and passes this pointer of type
-@code{double *} to a function compiled with GCC, dereferencing the
-pointer may cause a fatal signal.
-
-One way to solve this problem is to compile your entire program with GCC@.
-Another solution is to modify the function that is compiled with
-Sun CC to copy the argument into a local variable; local variables
-are always properly aligned. A third solution is to modify the function
-that uses the pointer to dereference it via the following function
-@code{access_double} instead of directly with @samp{*}:
-
-@smallexample
-inline double
-access_double (double *unaligned_ptr)
-@{
- union d2i @{ double d; int i[2]; @};
-
- union d2i *p = (union d2i *) unaligned_ptr;
- union d2i u;
-
- u.i[0] = p->i[0];
- u.i[1] = p->i[1];
-
- return u.d;
-@}
-@end smallexample
-
-@noindent
-Storing into the pointer can be done likewise with the same union.
-
-@item
-On Solaris, the @code{malloc} function in the @file{libmalloc.a} library
-may allocate memory that is only 4 byte aligned. Since GCC on the
-Sparc assumes that doubles are 8 byte aligned, this may result in a
-fatal signal if doubles are stored in memory allocated by the
-@file{libmalloc.a} library.
-
-The solution is to not use the @file{libmalloc.a} library. Use instead
-@code{malloc} and related functions from @file{libc.a}; they do not have
-this problem.
-
-@item
-Sun forgot to include a static version of @file{libdl.a} with some
-versions of SunOS (mainly 4.1). This results in undefined symbols when
-linking static binaries (that is, if you use @option{-static}). If you
-see undefined symbols @code{_dlclose}, @code{_dlsym} or @code{_dlopen}
-when linking, compile and link against the file
-@file{mit/util/misc/dlsym.c} from the MIT version of X windows.
-
-@item
-The 128-bit long double format that the Sparc port supports currently
-works by using the architecturally defined quad-word floating point
-instructions. Since there is no hardware that supports these
-instructions they must be emulated by the operating system. Long
-doubles do not work in Sun OS versions 4.0.3 and earlier, because the
-kernel emulator uses an obsolete and incompatible format. Long doubles
-do not work in Sun OS version 4.1.1 due to a problem in a Sun library.
-Long doubles do work on Sun OS versions 4.1.2 and higher, but GCC
-does not enable them by default. Long doubles appear to work in Sun OS
-5.x (Solaris 2.x).
-
-@item
-On HP-UX version 9.01 on the HP PA, the HP compiler @code{cc} does not
-compile GCC correctly. We do not yet know why. However, GCC
-compiled on earlier HP-UX versions works properly on HP-UX 9.01 and can
-compile itself properly on 9.01.
-
-@item
-On the HP PA machine, ADB sometimes fails to work on functions compiled
-with GCC@. Specifically, it fails to work on functions that use
-@code{alloca} or variable-size arrays. This is because GCC doesn't
-generate HP-UX unwind descriptors for such functions. It may even be
-impossible to generate them.
-
-@item
-Debugging (@option{-g}) is not supported on the HP PA machine, unless you use
-the preliminary GNU tools (@pxref{Installation}).
-
-@item
-Taking the address of a label may generate errors from the HP-UX
-PA assembler. GAS for the PA does not have this problem.
-
-@item
-Using floating point parameters for indirect calls to static functions
-will not work when using the HP assembler. There simply is no way for GCC
-to specify what registers hold arguments for static functions when using
-the HP assembler. GAS for the PA does not have this problem.
-
-@item
-In extremely rare cases involving some very large functions you may
-receive errors from the HP linker complaining about an out of bounds
-unconditional branch offset. This used to occur more often in previous
-versions of GCC, but is now exceptionally rare. If you should run
-into it, you can work around by making your function smaller.
-
-@item
-GCC compiled code sometimes emits warnings from the HP-UX assembler of
-the form:
-
-@smallexample
-(warning) Use of GR3 when
- frame >= 8192 may cause conflict.
-@end smallexample
-
-These warnings are harmless and can be safely ignored.
-
-@item
-The current version of the assembler (@file{/bin/as}) for the RS/6000
-has certain problems that prevent the @option{-g} option in GCC from
-working. Note that @file{Makefile.in} uses @option{-g} by default when
-compiling @file{libgcc2.c}.
-
-IBM has produced a fixed version of the assembler. The upgraded
-assembler unfortunately was not included in any of the AIX 3.2 update
-PTF releases (3.2.2, 3.2.3, or 3.2.3e). Users of AIX 3.1 should request
-PTF U403044 from IBM and users of AIX 3.2 should request PTF U416277.
-See the file @file{README.RS6000} for more details on these updates.
-
-You can test for the presence of a fixed assembler by using the
-command
-
-@smallexample
-as -u < /dev/null
-@end smallexample
-
-@noindent
-If the command exits normally, the assembler fix already is installed.
-If the assembler complains that @option{-u} is an unknown flag, you need to
-order the fix.
-
-@item
-On the IBM RS/6000, compiling code of the form
-
-@smallexample
-extern int foo;
-
-@dots{} foo @dots{}
-
-static int foo;
-@end smallexample
-
-@noindent
-will cause the linker to report an undefined symbol @code{foo}.
-Although this behavior differs from most other systems, it is not a
-bug because redefining an @code{extern} variable as @code{static}
-is undefined in ISO C@.
-
-@item
-AIX on the RS/6000 provides support (NLS) for environments outside of
-the United States. Compilers and assemblers use NLS to support
-locale-specific representations of various objects including
-floating-point numbers (@samp{.} vs @samp{,} for separating decimal fractions).
-There have been problems reported where the library linked with GCC does
-not produce the same floating-point formats that the assembler accepts.
-If you have this problem, set the @env{LANG} environment variable to
-@samp{C} or @samp{En_US}.
-
-@item
-@opindex fdollars-in-identifiers
-Even if you specify @option{-fdollars-in-identifiers},
-you cannot successfully use @samp{$} in identifiers on the RS/6000 due
-to a restriction in the IBM assembler. GAS supports these
-identifiers.
-
-@item
-On the RS/6000, XLC version 1.3.0.0 will miscompile @file{jump.c}. XLC
-version 1.3.0.1 or later fixes this problem. You can obtain XLC-1.3.0.2
-by requesting PTF 421749 from IBM@.
-
-@item
-@opindex mno-serialize-volatile
-There is an assembler bug in versions of DG/UX prior to 5.4.2.01 that
-occurs when the @samp{fldcr} instruction is used. GCC uses
-@samp{fldcr} on the 88100 to serialize volatile memory references. Use
-the option @option{-mno-serialize-volatile} if your version of the
-assembler has this bug.
-
-@item
-On VMS, GAS versions 1.38.1 and earlier may cause spurious warning
-messages from the linker. These warning messages complain of mismatched
-psect attributes. You can ignore them. @xref{VMS Install}.
-
-@item
-On NewsOS version 3, if you include both of the files @file{stddef.h}
-and @file{sys/types.h}, you get an error because there are two typedefs
-of @code{size_t}. You should change @file{sys/types.h} by adding these
-lines around the definition of @code{size_t}:
-
-@smallexample
-#ifndef _SIZE_T
-#define _SIZE_T
-@var{actual-typedef-here}
-#endif
-@end smallexample
-
-@cindex Alliant
-@item
-On the Alliant, the system's own convention for returning structures
-and unions is unusual, and is not compatible with GCC no matter
-what options are used.
-
-@cindex RT PC
-@cindex IBM RT PC
-@item
-@opindex mhc-struct-return
-On the IBM RT PC, the MetaWare HighC compiler (hc) uses a different
-convention for structure and union returning. Use the option
-@option{-mhc-struct-return} to tell GCC to use a convention compatible
-with it.
-
-@cindex Vax calling convention
-@cindex Ultrix calling convention
-@item
-@opindex fcall-saved
-On Ultrix, the Fortran compiler expects registers 2 through 5 to be saved
-by function calls. However, the C compiler uses conventions compatible
-with BSD Unix: registers 2 through 5 may be clobbered by function calls.
-
-GCC uses the same convention as the Ultrix C compiler. You can use
-these options to produce code compatible with the Fortran compiler:
-
-@smallexample
--fcall-saved-r2 -fcall-saved-r3 -fcall-saved-r4 -fcall-saved-r5
-@end smallexample
-
-@item
-On the WE32k, you may find that programs compiled with GCC do not
-work with the standard shared C library. You may need to link with
-the ordinary C compiler. If you do so, you must specify the following
-options:
-
-@smallexample
--L/usr/local/lib/gcc-lib/we32k-att-sysv/2.8.1 -lgcc -lc_s
-@end smallexample
-
-The first specifies where to find the library @file{libgcc.a}
-specified with the @option{-lgcc} option.
-
-GCC does linking by invoking @command{ld}, just as @command{cc} does, and
-there is no reason why it @emph{should} matter which compilation program
-you use to invoke @command{ld}. If someone tracks this problem down,
-it can probably be fixed easily.
-
-@item
-On the Alpha, you may get assembler errors about invalid syntax as a
-result of floating point constants. This is due to a bug in the C
-library functions @code{ecvt}, @code{fcvt} and @code{gcvt}. Given valid
-floating point numbers, they sometimes print @samp{NaN}.
-
-@item
-On Irix 4.0.5F (and perhaps in some other versions), an assembler bug
-sometimes reorders instructions incorrectly when optimization is turned
-on. If you think this may be happening to you, try using the GNU
-assembler; GAS version 2.1 supports ECOFF on Irix.
-
-@opindex noasmopt
-Or use the @option{-noasmopt} option when you compile GCC with itself,
-and then again when you compile your program. (This is a temporary
-kludge to turn off assembler optimization on Irix.) If this proves to
-be what you need, edit the assembler spec in the file @file{specs} so
-that it unconditionally passes @option{-O0} to the assembler, and never
-passes @option{-O2} or @option{-O3}.
-@end itemize
-
-@node External Bugs
-@section Problems Compiling Certain Programs
-
-@c prevent bad page break with this line
-Certain programs have problems compiling.
-
-@itemize @bullet
-@item
-Parse errors may occur compiling X11 on a Decstation running Ultrix 4.2
-because of problems in DEC's versions of the X11 header files
-@file{X11/Xlib.h} and @file{X11/Xutil.h}. People recommend adding
-@option{-I/usr/include/mit} to use the MIT versions of the header files,
-using the @option{-traditional} switch to turn off ISO C, or fixing the
-header files by adding this:
-
-@example
-#ifdef __STDC__
-#define NeedFunctionPrototypes 0
-#endif
-@end example
-
-@item
-On various 386 Unix systems derived from System V, including SCO, ISC,
-and ESIX, you may get error messages about running out of virtual memory
-while compiling certain programs.
-
-You can prevent this problem by linking GCC with the GNU malloc
-(which thus replaces the malloc that comes with the system). GNU malloc
-is available as a separate package, and also in the file
-@file{src/gmalloc.c} in the GNU Emacs 19 distribution.
-
-If you have installed GNU malloc as a separate library package, use this
-option when you relink GCC:
-
-@example
-MALLOC=/usr/local/lib/libgmalloc.a
-@end example
-
-Alternatively, if you have compiled @file{gmalloc.c} from Emacs 19, copy
-the object file to @file{gmalloc.o} and use this option when you relink
-GCC:
-
-@example
-MALLOC=gmalloc.o
-@end example
-@end itemize
-
-@node Incompatibilities
-@section Incompatibilities of GCC
-@cindex incompatibilities of GCC
-@opindex traditional
-
-There are several noteworthy incompatibilities between GNU C and K&R
-(non-ISO) versions of C@. The @option{-traditional} option
-eliminates many of these incompatibilities, @emph{but not all}, by
-telling GCC to behave like a K&R C compiler.
-
-@itemize @bullet
-@cindex string constants
-@cindex read-only strings
-@cindex shared strings
-@item
-GCC normally makes string constants read-only. If several
-identical-looking string constants are used, GCC stores only one
-copy of the string.
-
-@cindex @code{mktemp}, and constant strings
-One consequence is that you cannot call @code{mktemp} with a string
-constant argument. The function @code{mktemp} always alters the
-string its argument points to.
-
-@cindex @code{sscanf}, and constant strings
-@cindex @code{fscanf}, and constant strings
-@cindex @code{scanf}, and constant strings
-Another consequence is that @code{sscanf} does not work on some systems
-when passed a string constant as its format control string or input.
-This is because @code{sscanf} incorrectly tries to write into the string
-constant. Likewise @code{fscanf} and @code{scanf}.
-
-@opindex fwritable-strings
-The best solution to these problems is to change the program to use
-@code{char}-array variables with initialization strings for these
-purposes instead of string constants. But if this is not possible,
-you can use the @option{-fwritable-strings} flag, which directs GCC
-to handle string constants the same way most C compilers do.
-@option{-traditional} also has this effect, among others.
-
-@item
-@code{-2147483648} is positive.
-
-This is because 2147483648 cannot fit in the type @code{int}, so
-(following the ISO C rules) its data type is @code{unsigned long int}.
-Negating this value yields 2147483648 again.
-
-@item
-GCC does not substitute macro arguments when they appear inside of
-string constants. For example, the following macro in GCC
-
-@example
-#define foo(a) "a"
-@end example
-
-@noindent
-will produce output @code{"a"} regardless of what the argument @var{a} is.
-
-The @option{-traditional} option directs GCC to handle such cases
-(among others) in the old-fashioned (non-ISO) fashion.
-
-@cindex @code{setjmp} incompatibilities
-@cindex @code{longjmp} incompatibilities
-@item
-When you use @code{setjmp} and @code{longjmp}, the only automatic
-variables guaranteed to remain valid are those declared
-@code{volatile}. This is a consequence of automatic register
-allocation. Consider this function:
-
-@example
-jmp_buf j;
-
-foo ()
-@{
- int a, b;
-
- a = fun1 ();
- if (setjmp (j))
- return a;
-
- a = fun2 ();
- /* @r{@code{longjmp (j)} may occur in @code{fun3}.} */
- return a + fun3 ();
-@}
-@end example
-
-Here @code{a} may or may not be restored to its first value when the
-@code{longjmp} occurs. If @code{a} is allocated in a register, then
-its first value is restored; otherwise, it keeps the last value stored
-in it.
-
-@opindex W
-If you use the @option{-W} option with the @option{-O} option, you will
-get a warning when GCC thinks such a problem might be possible.
-
-The @option{-traditional} option directs GCC to put variables in
-the stack by default, rather than in registers, in functions that
-call @code{setjmp}. This results in the behavior found in
-traditional C compilers.
-
-@item
-Programs that use preprocessing directives in the middle of macro
-arguments do not work with GCC@. For example, a program like this
-will not work:
-
-@example
-@group
-foobar (
-#define luser
- hack)
-@end group
-@end example
-
-ISO C does not permit such a construct. It would make sense to support
-it when @option{-traditional} is used, but it is too much work to
-implement.
-
-@item
-K&R compilers allow comments to cross over an inclusion boundary
-(i.e.@: started in an include file and ended in the including file). I think
-this would be quite ugly and can't imagine it could be needed.
-
-@cindex external declaration scope
-@cindex scope of external declarations
-@cindex declaration scope
-@item
-Declarations of external variables and functions within a block apply
-only to the block containing the declaration. In other words, they
-have the same scope as any other declaration in the same place.
-
-In some other C compilers, a @code{extern} declaration affects all the
-rest of the file even if it happens within a block.
-
-The @option{-traditional} option directs GCC to treat all @code{extern}
-declarations as global, like traditional compilers.
-
-@item
-In traditional C, you can combine @code{long}, etc., with a typedef name,
-as shown here:
-
-@example
-typedef int foo;
-typedef long foo bar;
-@end example
-
-In ISO C, this is not allowed: @code{long} and other type modifiers
-require an explicit @code{int}. Because this criterion is expressed
-by Bison grammar rules rather than C code, the @option{-traditional}
-flag cannot alter it.
-
-@cindex typedef names as function parameters
-@item
-PCC allows typedef names to be used as function parameters. The
-difficulty described immediately above applies here too.
-
-@item
-When in @option{-traditional} mode, GCC allows the following erroneous
-pair of declarations to appear together in a given scope:
-
-@example
-typedef int foo;
-typedef foo foo;
-@end example
-
-@item
-GCC treats all characters of identifiers as significant, even when in
-@option{-traditional} mode. According to K&R-1 (2.2), ``No more than the
-first eight characters are significant, although more may be used.''.
-Also according to K&R-1 (2.2), ``An identifier is a sequence of letters
-and digits; the first character must be a letter. The underscore _
-counts as a letter.'', but GCC also allows dollar signs in identifiers.
-
-@cindex whitespace
-@item
-PCC allows whitespace in the middle of compound assignment operators
-such as @samp{+=}. GCC, following the ISO standard, does not
-allow this. The difficulty described immediately above applies here
-too.
-
-@cindex apostrophes
-@cindex '
-@item
-GCC complains about unterminated character constants inside of
-preprocessing conditionals that fail. Some programs have English
-comments enclosed in conditionals that are guaranteed to fail; if these
-comments contain apostrophes, GCC will probably report an error. For
-example, this code would produce an error:
-
-@example
-#if 0
-You can't expect this to work.
-#endif
-@end example
-
-The best solution to such a problem is to put the text into an actual
-C comment delimited by @samp{/*@dots{}*/}. However,
-@option{-traditional} suppresses these error messages.
-
-@item
-Many user programs contain the declaration @samp{long time ();}. In the
-past, the system header files on many systems did not actually declare
-@code{time}, so it did not matter what type your program declared it to
-return. But in systems with ISO C headers, @code{time} is declared to
-return @code{time_t}, and if that is not the same as @code{long}, then
-@samp{long time ();} is erroneous.
-
-The solution is to change your program to use appropriate system headers
-(@code{<time.h>} on systems with ISO C headers) and not to declare
-@code{time} if the system header files declare it, or failing that to
-use @code{time_t} as the return type of @code{time}.
-
-@cindex @code{float} as function value type
-@item
-When compiling functions that return @code{float}, PCC converts it to
-a double. GCC actually returns a @code{float}. If you are concerned
-with PCC compatibility, you should declare your functions to return
-@code{double}; you might as well say what you mean.
-
-@cindex structures
-@cindex unions
-@item
-When compiling functions that return structures or unions, GCC
-output code normally uses a method different from that used on most
-versions of Unix. As a result, code compiled with GCC cannot call
-a structure-returning function compiled with PCC, and vice versa.
-
-The method used by GCC is as follows: a structure or union which is
-1, 2, 4 or 8 bytes long is returned like a scalar. A structure or union
-with any other size is stored into an address supplied by the caller
-(usually in a special, fixed register, but on some machines it is passed
-on the stack). The machine-description macros @code{STRUCT_VALUE} and
-@code{STRUCT_INCOMING_VALUE} tell GCC where to pass this address.
-
-By contrast, PCC on most target machines returns structures and unions
-of any size by copying the data into an area of static storage, and then
-returning the address of that storage as if it were a pointer value.
-The caller must copy the data from that memory area to the place where
-the value is wanted. GCC does not use this method because it is
-slower and nonreentrant.
-
-On some newer machines, PCC uses a reentrant convention for all
-structure and union returning. GCC on most of these machines uses a
-compatible convention when returning structures and unions in memory,
-but still returns small structures and unions in registers.
-
-@opindex fpcc-struct-return
-You can tell GCC to use a compatible convention for all structure and
-union returning with the option @option{-fpcc-struct-return}.
-
-@cindex preprocessing tokens
-@cindex preprocessing numbers
-@item
-GCC complains about program fragments such as @samp{0x74ae-0x4000}
-which appear to be two hexadecimal constants separated by the minus
-operator. Actually, this string is a single @dfn{preprocessing token}.
-Each such token must correspond to one token in C@. Since this does not,
-GCC prints an error message. Although it may appear obvious that what
-is meant is an operator and two values, the ISO C standard specifically
-requires that this be treated as erroneous.
-
-A @dfn{preprocessing token} is a @dfn{preprocessing number} if it
-begins with a digit and is followed by letters, underscores, digits,
-periods and @samp{e+}, @samp{e-}, @samp{E+}, @samp{E-}, @samp{p+},
-@samp{p-}, @samp{P+}, or @samp{P-} character sequences. (In strict C89
-mode, the sequences @samp{p+}, @samp{p-}, @samp{P+} and @samp{P-} cannot
-appear in preprocessing numbers.)
-
-To make the above program fragment valid, place whitespace in front of
-the minus sign. This whitespace will end the preprocessing number.
-@end itemize
-
-@node Fixed Headers
-@section Fixed Header Files
-
-GCC needs to install corrected versions of some system header files.
-This is because most target systems have some header files that won't
-work with GCC unless they are changed. Some have bugs, some are
-incompatible with ISO C, and some depend on special features of other
-compilers.
-
-Installing GCC automatically creates and installs the fixed header
-files, by running a program called @code{fixincludes} (or for certain
-targets an alternative such as @code{fixinc.svr4}). Normally, you
-don't need to pay attention to this. But there are cases where it
-doesn't do the right thing automatically.
-
-@itemize @bullet
-@item
-If you update the system's header files, such as by installing a new
-system version, the fixed header files of GCC are not automatically
-updated. The easiest way to update them is to reinstall GCC@. (If
-you want to be clever, look in the makefile and you can find a
-shortcut.)
-
-@item
-On some systems, in particular SunOS 4, header file directories contain
-machine-specific symbolic links in certain places. This makes it
-possible to share most of the header files among hosts running the
-same version of SunOS 4 on different machine models.
-
-The programs that fix the header files do not understand this special
-way of using symbolic links; therefore, the directory of fixed header
-files is good only for the machine model used to build it.
-
-In SunOS 4, only programs that look inside the kernel will notice the
-difference between machine models. Therefore, for most purposes, you
-need not be concerned about this.
-
-It is possible to make separate sets of fixed header files for the
-different machine models, and arrange a structure of symbolic links so
-as to use the proper set, but you'll have to do this by hand.
-
-@item
-On Lynxos, GCC by default does not fix the header files. This is
-because bugs in the shell cause the @code{fixincludes} script to fail.
-
-This means you will encounter problems due to bugs in the system header
-files. It may be no comfort that they aren't GCC's fault, but it
-does mean that there's nothing for us to do about them.
-@end itemize
-
-@node Standard Libraries
-@section Standard Libraries
-
-@opindex Wall
-GCC by itself attempts to be a conforming freestanding implementation.
-@xref{Standards,,Language Standards Supported by GCC}, for details of
-what this means. Beyond the library facilities required of such an
-implementation, the rest of the C library is supplied by the vendor of
-the operating system. If that C library doesn't conform to the C
-standards, then your programs might get warnings (especially when using
-@option{-Wall}) that you don't expect.
-
-For example, the @code{sprintf} function on SunOS 4.1.3 returns
-@code{char *} while the C standard says that @code{sprintf} returns an
-@code{int}. The @code{fixincludes} program could make the prototype for
-this function match the Standard, but that would be wrong, since the
-function will still return @code{char *}.
-
-If you need a Standard compliant library, then you need to find one, as
-GCC does not provide one. The GNU C library (called @code{glibc})
-provides ISO C, POSIX, BSD, SystemV and X/Open compatibility for
-GNU/Linux and HURD-based GNU systems; no recent version of it supports
-other systems, though some very old versions did. Version 2.2 of the
-GNU C library includes nearly complete C99 support. You could also ask
-your operating system vendor if newer libraries are available.
-
-@node Disappointments
-@section Disappointments and Misunderstandings
-
-These problems are perhaps regrettable, but we don't know any practical
-way around them.
-
-@itemize @bullet
-@item
-Certain local variables aren't recognized by debuggers when you compile
-with optimization.
-
-This occurs because sometimes GCC optimizes the variable out of
-existence. There is no way to tell the debugger how to compute the
-value such a variable ``would have had'', and it is not clear that would
-be desirable anyway. So GCC simply does not mention the eliminated
-variable when it writes debugging information.
-
-You have to expect a certain amount of disagreement between the
-executable and your source code, when you use optimization.
-
-@cindex conflicting types
-@cindex scope of declaration
-@item
-Users often think it is a bug when GCC reports an error for code
-like this:
-
-@example
-int foo (struct mumble *);
-
-struct mumble @{ @dots{} @};
-
-int foo (struct mumble *x)
-@{ @dots{} @}
-@end example
-
-This code really is erroneous, because the scope of @code{struct
-mumble} in the prototype is limited to the argument list containing it.
-It does not refer to the @code{struct mumble} defined with file scope
-immediately below---they are two unrelated types with similar names in
-different scopes.
-
-But in the definition of @code{foo}, the file-scope type is used
-because that is available to be inherited. Thus, the definition and
-the prototype do not match, and you get an error.
-
-This behavior may seem silly, but it's what the ISO standard specifies.
-It is easy enough for you to make your code work by moving the
-definition of @code{struct mumble} above the prototype. It's not worth
-being incompatible with ISO C just to avoid an error for the example
-shown above.
-
-@item
-Accesses to bit-fields even in volatile objects works by accessing larger
-objects, such as a byte or a word. You cannot rely on what size of
-object is accessed in order to read or write the bit-field; it may even
-vary for a given bit-field according to the precise usage.
-
-If you care about controlling the amount of memory that is accessed, use
-volatile but do not use bit-fields.
-
-@item
-GCC comes with shell scripts to fix certain known problems in system
-header files. They install corrected copies of various header files in
-a special directory where only GCC will normally look for them. The
-scripts adapt to various systems by searching all the system header
-files for the problem cases that we know about.
-
-If new system header files are installed, nothing automatically arranges
-to update the corrected header files. You will have to reinstall GCC
-to fix the new header files. More specifically, go to the build
-directory and delete the files @file{stmp-fixinc} and
-@file{stmp-headers}, and the subdirectory @code{include}; then do
-@samp{make install} again.
-
-@item
-@cindex floating point precision
-On 68000 and x86 systems, for instance, you can get paradoxical results
-if you test the precise values of floating point numbers. For example,
-you can find that a floating point value which is not a NaN is not equal
-to itself. This results from the fact that the floating point registers
-hold a few more bits of precision than fit in a @code{double} in memory.
-Compiled code moves values between memory and floating point registers
-at its convenience, and moving them into memory truncates them.
-
-@opindex ffloat-store
-You can partially avoid this problem by using the @option{-ffloat-store}
-option (@pxref{Optimize Options}).
-
-@item
-On the MIPS, variable argument functions using @file{varargs.h}
-cannot have a floating point value for the first argument. The
-reason for this is that in the absence of a prototype in scope,
-if the first argument is a floating point, it is passed in a
-floating point register, rather than an integer register.
-
-If the code is rewritten to use the ISO standard @file{stdarg.h}
-method of variable arguments, and the prototype is in scope at
-the time of the call, everything will work fine.
-
-@item
-On the H8/300 and H8/300H, variable argument functions must be
-implemented using the ISO standard @file{stdarg.h} method of
-variable arguments. Furthermore, calls to functions using @file{stdarg.h}
-variable arguments must have a prototype for the called function
-in scope at the time of the call.
-@end itemize
-
-@node C++ Misunderstandings
-@section Common Misunderstandings with GNU C++
-
-@cindex misunderstandings in C++
-@cindex surprises in C++
-@cindex C++ misunderstandings
-C++ is a complex language and an evolving one, and its standard
-definition (the ISO C++ standard) was only recently completed. As a
-result, your C++ compiler may occasionally surprise you, even when its
-behavior is correct. This section discusses some areas that frequently
-give rise to questions of this sort.
-
-@menu
-* Static Definitions:: Static member declarations are not definitions
-* Temporaries:: Temporaries may vanish before you expect
-* Copy Assignment:: Copy Assignment operators copy virtual bases twice
-@end menu
-
-@node Static Definitions
-@subsection Declare @emph{and} Define Static Members
-
-@cindex C++ static data, declaring and defining
-@cindex static data in C++, declaring and defining
-@cindex declaring static data in C++
-@cindex defining static data in C++
-When a class has static data members, it is not enough to @emph{declare}
-the static member; you must also @emph{define} it. For example:
-
-@example
-class Foo
-@{
- @dots{}
- void method();
- static int bar;
-@};
-@end example
-
-This declaration only establishes that the class @code{Foo} has an
-@code{int} named @code{Foo::bar}, and a member function named
-@code{Foo::method}. But you still need to define @emph{both}
-@code{method} and @code{bar} elsewhere. According to the ISO
-standard, you must supply an initializer in one (and only one) source
-file, such as:
-
-@example
-int Foo::bar = 0;
-@end example
-
-Other C++ compilers may not correctly implement the standard behavior.
-As a result, when you switch to @code{g++} from one of these compilers,
-you may discover that a program that appeared to work correctly in fact
-does not conform to the standard: @code{g++} reports as undefined
-symbols any static data members that lack definitions.
-
-@node Temporaries
-@subsection Temporaries May Vanish Before You Expect
-
-@cindex temporaries, lifetime of
-@cindex portions of temporary objects, pointers to
-It is dangerous to use pointers or references to @emph{portions} of a
-temporary object. The compiler may very well delete the object before
-you expect it to, leaving a pointer to garbage. The most common place
-where this problem crops up is in classes like string classes,
-especially ones that define a conversion function to type @code{char *}
-or @code{const char *}---which is one reason why the standard
-@code{string} class requires you to call the @code{c_str} member
-function. However, any class that returns a pointer to some internal
-structure is potentially subject to this problem.
-
-For example, a program may use a function @code{strfunc} that returns
-@code{string} objects, and another function @code{charfunc} that
-operates on pointers to @code{char}:
-
-@example
-string strfunc ();
-void charfunc (const char *);
-
-void
-f ()
-@{
- const char *p = strfunc().c_str();
- @dots{}
- charfunc (p);
- @dots{}
- charfunc (p);
-@}
-@end example
-
-@noindent
-In this situation, it may seem reasonable to save a pointer to the C
-string returned by the @code{c_str} member function and use that rather
-than call @code{c_str} repeatedly. However, the temporary string
-created by the call to @code{strfunc} is destroyed after @code{p} is
-initialized, at which point @code{p} is left pointing to freed memory.
-
-Code like this may run successfully under some other compilers,
-particularly obsolete cfront-based compilers that delete temporaries
-along with normal local variables. However, the GNU C++ behavior is
-standard-conforming, so if your program depends on late destruction of
-temporaries it is not portable.
-
-The safe way to write such code is to give the temporary a name, which
-forces it to remain until the end of the scope of the name. For
-example:
-
-@example
-string& tmp = strfunc ();
-charfunc (tmp.c_str ());
-@end example
-
-@node Copy Assignment
-@subsection Implicit Copy-Assignment for Virtual Bases
-
-When a base class is virtual, only one subobject of the base class
-belongs to each full object. Also, the constructors and destructors are
-invoked only once, and called from the most-derived class. However, such
-objects behave unspecified when being assigned. For example:
-
-@example
-struct Base@{
- char *name;
- Base(char *n) : name(strdup(n))@{@}
- Base& operator= (const Base& other)@{
- free (name);
- name = strdup (other.name);
- @}
-@};
-
-struct A:virtual Base@{
- int val;
- A():Base("A")@{@}
-@};
-
-struct B:virtual Base@{
- int bval;
- B():Base("B")@{@}
-@};
-
-struct Derived:public A, public B@{
- Derived():Base("Derived")@{@}
-@};
-
-void func(Derived &d1, Derived &d2)
-@{
- d1 = d2;
-@}
-@end example
-
-The C++ standard specifies that @samp{Base::Base} is only called once
-when constructing or copy-constructing a Derived object. It is
-unspecified whether @samp{Base::operator=} is called more than once when
-the implicit copy-assignment for Derived objects is invoked (as it is
-inside @samp{func} in the example).
-
-g++ implements the ``intuitive'' algorithm for copy-assignment: assign all
-direct bases, then assign all members. In that algorithm, the virtual
-base subobject can be encountered many times. In the example, copying
-proceeds in the following order: @samp{val}, @samp{name} (via
-@code{strdup}), @samp{bval}, and @samp{name} again.
-
-If application code relies on copy-assignment, a user-defined
-copy-assignment operator removes any uncertainties. With such an
-operator, the application can define whether and how the virtual base
-subobject is assigned.
-
-@node Protoize Caveats
-@section Caveats of using @command{protoize}
-
-The conversion programs @command{protoize} and @command{unprotoize} can
-sometimes change a source file in a way that won't work unless you
-rearrange it.
-
-@itemize @bullet
-@item
-@command{protoize} can insert references to a type name or type tag before
-the definition, or in a file where they are not defined.
-
-If this happens, compiler error messages should show you where the new
-references are, so fixing the file by hand is straightforward.
-
-@item
-There are some C constructs which @command{protoize} cannot figure out.
-For example, it can't determine argument types for declaring a
-pointer-to-function variable; this you must do by hand. @command{protoize}
-inserts a comment containing @samp{???} each time it finds such a
-variable; so you can find all such variables by searching for this
-string. ISO C does not require declaring the argument types of
-pointer-to-function types.
-
-@item
-Using @command{unprotoize} can easily introduce bugs. If the program
-relied on prototypes to bring about conversion of arguments, these
-conversions will not take place in the program without prototypes.
-One case in which you can be sure @command{unprotoize} is safe is when
-you are removing prototypes that were made with @command{protoize}; if
-the program worked before without any prototypes, it will work again
-without them.
-
-@opindex Wconversion
-You can find all the places where this problem might occur by compiling
-the program with the @option{-Wconversion} option. It prints a warning
-whenever an argument is converted.
-
-@item
-Both conversion programs can be confused if there are macro calls in and
-around the text to be converted. In other words, the standard syntax
-for a declaration or definition must not result from expanding a macro.
-This problem is inherent in the design of C and cannot be fixed. If
-only a few functions have confusing macro calls, you can easily convert
-them manually.
-
-@item
-@command{protoize} cannot get the argument types for a function whose
-definition was not actually compiled due to preprocessing conditionals.
-When this happens, @command{protoize} changes nothing in regard to such
-a function. @command{protoize} tries to detect such instances and warn
-about them.
-
-You can generally work around this problem by using @command{protoize} step
-by step, each time specifying a different set of @option{-D} options for
-compilation, until all of the functions have been converted. There is
-no automatic way to verify that you have got them all, however.
-
-@item
-Confusion may result if there is an occasion to convert a function
-declaration or definition in a region of source code where there is more
-than one formal parameter list present. Thus, attempts to convert code
-containing multiple (conditionally compiled) versions of a single
-function header (in the same vicinity) may not produce the desired (or
-expected) results.
-
-If you plan on converting source files which contain such code, it is
-recommended that you first make sure that each conditionally compiled
-region of source code which contains an alternative function header also
-contains at least one additional follower token (past the final right
-parenthesis of the function header). This should circumvent the
-problem.
-
-@item
-@command{unprotoize} can become confused when trying to convert a function
-definition or declaration which contains a declaration for a
-pointer-to-function formal argument which has the same name as the
-function being defined or declared. We recommend you avoid such choices
-of formal parameter names.
-
-@item
-You might also want to correct some of the indentation by hand and break
-long lines. (The conversion programs don't write lines longer than
-eighty characters in any case.)
-@end itemize
-
-@node Non-bugs
-@section Certain Changes We Don't Want to Make
-
-This section lists changes that people frequently request, but which
-we do not make because we think GCC is better without them.
-
-@itemize @bullet
-@item
-Checking the number and type of arguments to a function which has an
-old-fashioned definition and no prototype.
-
-Such a feature would work only occasionally---only for calls that appear
-in the same file as the called function, following the definition. The
-only way to check all calls reliably is to add a prototype for the
-function. But adding a prototype eliminates the motivation for this
-feature. So the feature is not worthwhile.
-
-@item
-Warning about using an expression whose type is signed as a shift count.
-
-Shift count operands are probably signed more often than unsigned.
-Warning about this would cause far more annoyance than good.
-
-@item
-Warning about assigning a signed value to an unsigned variable.
-
-Such assignments must be very common; warning about them would cause
-more annoyance than good.
-
-@item
-Warning when a non-void function value is ignored.
-
-Coming as I do from a Lisp background, I balk at the idea that there is
-something dangerous about discarding a value. There are functions that
-return values which some callers may find useful; it makes no sense to
-clutter the program with a cast to @code{void} whenever the value isn't
-useful.
-
-@item
-@opindex fshort-enums
-Making @option{-fshort-enums} the default.
-
-This would cause storage layout to be incompatible with most other C
-compilers. And it doesn't seem very important, given that you can get
-the same result in other ways. The case where it matters most is when
-the enumeration-valued object is inside a structure, and in that case
-you can specify a field width explicitly.
-
-@item
-Making bit-fields unsigned by default on particular machines where ``the
-ABI standard'' says to do so.
-
-The ISO C standard leaves it up to the implementation whether a bit-field
-declared plain @code{int} is signed or not. This in effect creates two
-alternative dialects of C@.
-
-@opindex fsigned-bitfields
-@opindex funsigned-bitfields
-The GNU C compiler supports both dialects; you can specify the signed
-dialect with @option{-fsigned-bitfields} and the unsigned dialect with
-@option{-funsigned-bitfields}. However, this leaves open the question of
-which dialect to use by default.
-
-Currently, the preferred dialect makes plain bit-fields signed, because
-this is simplest. Since @code{int} is the same as @code{signed int} in
-every other context, it is cleanest for them to be the same in bit-fields
-as well.
-
-Some computer manufacturers have published Application Binary Interface
-standards which specify that plain bit-fields should be unsigned. It is
-a mistake, however, to say anything about this issue in an ABI@. This is
-because the handling of plain bit-fields distinguishes two dialects of C@.
-Both dialects are meaningful on every type of machine. Whether a
-particular object file was compiled using signed bit-fields or unsigned
-is of no concern to other object files, even if they access the same
-bit-fields in the same data structures.
-
-A given program is written in one or the other of these two dialects.
-The program stands a chance to work on most any machine if it is
-compiled with the proper dialect. It is unlikely to work at all if
-compiled with the wrong dialect.
-
-Many users appreciate the GNU C compiler because it provides an
-environment that is uniform across machines. These users would be
-inconvenienced if the compiler treated plain bit-fields differently on
-certain machines.
-
-Occasionally users write programs intended only for a particular machine
-type. On these occasions, the users would benefit if the GNU C compiler
-were to support by default the same dialect as the other compilers on
-that machine. But such applications are rare. And users writing a
-program to run on more than one type of machine cannot possibly benefit
-from this kind of compatibility.
-
-This is why GCC does and will treat plain bit-fields in the same
-fashion on all types of machines (by default).
-
-There are some arguments for making bit-fields unsigned by default on all
-machines. If, for example, this becomes a universal de facto standard,
-it would make sense for GCC to go along with it. This is something
-to be considered in the future.
-
-(Of course, users strongly concerned about portability should indicate
-explicitly in each bit-field whether it is signed or not. In this way,
-they write programs which have the same meaning in both C dialects.)
-
-@item
-@opindex ansi
-@opindex traditional
-@opindex std
-Undefining @code{__STDC__} when @option{-ansi} is not used.
-
-Currently, GCC defines @code{__STDC__} as long as you don't use
-@option{-traditional}. This provides good results in practice.
-
-Programmers normally use conditionals on @code{__STDC__} to ask whether
-it is safe to use certain features of ISO C, such as function
-prototypes or ISO token concatenation. Since plain @command{gcc} supports
-all the features of ISO C, the correct answer to these questions is
-``yes''.
-
-Some users try to use @code{__STDC__} to check for the availability of
-certain library facilities. This is actually incorrect usage in an ISO
-C program, because the ISO C standard says that a conforming
-freestanding implementation should define @code{__STDC__} even though it
-does not have the library facilities. @samp{gcc -ansi -pedantic} is a
-conforming freestanding implementation, and it is therefore required to
-define @code{__STDC__}, even though it does not come with an ISO C
-library.
-
-Sometimes people say that defining @code{__STDC__} in a compiler that
-does not completely conform to the ISO C standard somehow violates the
-standard. This is illogical. The standard is a standard for compilers
-that claim to support ISO C, such as @samp{gcc -ansi}---not for other
-compilers such as plain @command{gcc}. Whatever the ISO C standard says
-is relevant to the design of plain @command{gcc} without @option{-ansi} only
-for pragmatic reasons, not as a requirement.
-
-GCC normally defines @code{__STDC__} to be 1, and in addition
-defines @code{__STRICT_ANSI__} if you specify the @option{-ansi} option,
-or a @option{-std} option for strict conformance to some version of ISO C@.
-On some hosts, system include files use a different convention, where
-@code{__STDC__} is normally 0, but is 1 if the user specifies strict
-conformance to the C Standard. GCC follows the host convention when
-processing system include files, but when processing user files it follows
-the usual GNU C convention.
-
-@item
-Undefining @code{__STDC__} in C++.
-
-Programs written to compile with C++-to-C translators get the
-value of @code{__STDC__} that goes with the C compiler that is
-subsequently used. These programs must test @code{__STDC__}
-to determine what kind of C preprocessor that compiler uses:
-whether they should concatenate tokens in the ISO C fashion
-or in the traditional fashion.
-
-These programs work properly with GNU C++ if @code{__STDC__} is defined.
-They would not work otherwise.
-
-In addition, many header files are written to provide prototypes in ISO
-C but not in traditional C@. Many of these header files can work without
-change in C++ provided @code{__STDC__} is defined. If @code{__STDC__}
-is not defined, they will all fail, and will all need to be changed to
-test explicitly for C++ as well.
-
-@item
-Deleting ``empty'' loops.
-
-Historically, GCC has not deleted ``empty'' loops under the
-assumption that the most likely reason you would put one in a program is
-to have a delay, so deleting them will not make real programs run any
-faster.
-
-However, the rationale here is that optimization of a nonempty loop
-cannot produce an empty one, which holds for C but is not always the
-case for C++.
-
-@opindex funroll-loops
-Moreover, with @option{-funroll-loops} small ``empty'' loops are already
-removed, so the current behavior is both sub-optimal and inconsistent
-and will change in the future.
-
-@item
-Making side effects happen in the same order as in some other compiler.
-
-@cindex side effects, order of evaluation
-@cindex order of evaluation, side effects
-It is never safe to depend on the order of evaluation of side effects.
-For example, a function call like this may very well behave differently
-from one compiler to another:
-
-@example
-void func (int, int);
-
-int i = 2;
-func (i++, i++);
-@end example
-
-There is no guarantee (in either the C or the C++ standard language
-definitions) that the increments will be evaluated in any particular
-order. Either increment might happen first. @code{func} might get the
-arguments @samp{2, 3}, or it might get @samp{3, 2}, or even @samp{2, 2}.
-
-@item
-Not allowing structures with volatile fields in registers.
-
-Strictly speaking, there is no prohibition in the ISO C standard
-against allowing structures with volatile fields in registers, but
-it does not seem to make any sense and is probably not what you wanted
-to do. So the compiler will give an error message in this case.
-
-@item
-Making certain warnings into errors by default.
-
-Some ISO C testsuites report failure when the compiler does not produce
-an error message for a certain program.
-
-@opindex pedantic-errors
-ISO C requires a ``diagnostic'' message for certain kinds of invalid
-programs, but a warning is defined by GCC to count as a diagnostic. If
-GCC produces a warning but not an error, that is correct ISO C support.
-If test suites call this ``failure'', they should be run with the GCC
-option @option{-pedantic-errors}, which will turn these warnings into
-errors.
-
-@end itemize
-
-@node Warnings and Errors
-@section Warning Messages and Error Messages
-
-@cindex error messages
-@cindex warnings vs errors
-@cindex messages, warning and error
-The GNU compiler can produce two kinds of diagnostics: errors and
-warnings. Each kind has a different purpose:
-
-@itemize @w{}
-@item
-@dfn{Errors} report problems that make it impossible to compile your
-program. GCC reports errors with the source file name and line
-number where the problem is apparent.
-
-@item
-@dfn{Warnings} report other unusual conditions in your code that
-@emph{may} indicate a problem, although compilation can (and does)
-proceed. Warning messages also report the source file name and line
-number, but include the text @samp{warning:} to distinguish them
-from error messages.
-@end itemize
-
-Warnings may indicate danger points where you should check to make sure
-that your program really does what you intend; or the use of obsolete
-features; or the use of nonstandard features of GNU C or C++. Many
-warnings are issued only if you ask for them, with one of the @option{-W}
-options (for instance, @option{-Wall} requests a variety of useful
-warnings).
-
-@opindex pedantic
-@opindex pedantic-errors
-GCC always tries to compile your program if possible; it never
-gratuitously rejects a program whose meaning is clear merely because
-(for instance) it fails to conform to a standard. In some cases,
-however, the C and C++ standards specify that certain extensions are
-forbidden, and a diagnostic @emph{must} be issued by a conforming
-compiler. The @option{-pedantic} option tells GCC to issue warnings in
-such cases; @option{-pedantic-errors} says to make them errors instead.
-This does not mean that @emph{all} non-ISO constructs get warnings
-or errors.
-
-@xref{Warning Options,,Options to Request or Suppress Warnings}, for
-more detail on these and related command-line options.
-
-@node Bugs
-@chapter Reporting Bugs
-@cindex bugs
-@cindex reporting bugs
-
-Your bug reports play an essential role in making GCC reliable.
-
-When you encounter a problem, the first thing to do is to see if it is
-already known. @xref{Trouble}. If it isn't known, then you should
-report the problem.
-
-Reporting a bug may help you by bringing a solution to your problem, or
-it may not. (If it does not, look in the service directory; see
-@ref{Service}.) In any case, the principal function of a bug report is
-to help the entire community by making the next version of GCC work
-better. Bug reports are your contribution to the maintenance of GCC@.
-
-Since the maintainers are very overloaded, we cannot respond to every
-bug report. However, if the bug has not been fixed, we are likely to
-send you a patch and ask you to tell us whether it works.
-
-In order for a bug report to serve its purpose, you must include the
-information that makes for fixing the bug.
-
-@menu
-* Criteria: Bug Criteria. Have you really found a bug?
-* Where: Bug Lists. Where to send your bug report.
-* Reporting: Bug Reporting. How to report a bug effectively.
-* GNATS: gccbug. You can use a bug reporting tool.
-* Patches: Sending Patches. How to send a patch for GCC.
-* Known: Trouble. Known problems.
-* Help: Service. Where to ask for help.
-@end menu
-
-@node Bug Criteria,Bug Lists,,Bugs
-@section Have You Found a Bug?
-@cindex bug criteria
-
-If you are not sure whether you have found a bug, here are some guidelines:
-
-@itemize @bullet
-@cindex fatal signal
-@cindex core dump
-@item
-If the compiler gets a fatal signal, for any input whatever, that is a
-compiler bug. Reliable compilers never crash.
-
-@cindex invalid assembly code
-@cindex assembly code, invalid
-@item
-If the compiler produces invalid assembly code, for any input whatever
-(except an @code{asm} statement), that is a compiler bug, unless the
-compiler reports errors (not just warnings) which would ordinarily
-prevent the assembler from being run.
-
-@cindex undefined behavior
-@cindex undefined function value
-@cindex increment operators
-@item
-If the compiler produces valid assembly code that does not correctly
-execute the input source code, that is a compiler bug.
-
-However, you must double-check to make sure, because you may have run
-into an incompatibility between GNU C and traditional C
-(@pxref{Incompatibilities}). These incompatibilities might be considered
-bugs, but they are inescapable consequences of valuable features.
-
-Or you may have a program whose behavior is undefined, which happened
-by chance to give the desired results with another C or C++ compiler.
-
-For example, in many nonoptimizing compilers, you can write @samp{x;}
-at the end of a function instead of @samp{return x;}, with the same
-results. But the value of the function is undefined if @code{return}
-is omitted; it is not a bug when GCC produces different results.
-
-Problems often result from expressions with two increment operators,
-as in @code{f (*p++, *p++)}. Your previous compiler might have
-interpreted that expression the way you intended; GCC might
-interpret it another way. Neither compiler is wrong. The bug is
-in your code.
-
-After you have localized the error to a single source line, it should
-be easy to check for these things. If your program is correct and
-well defined, you have found a compiler bug.
-
-@item
-If the compiler produces an error message for valid input, that is a
-compiler bug.
-
-@cindex invalid input
-@item
-If the compiler does not produce an error message for invalid input,
-that is a compiler bug. However, you should note that your idea of
-``invalid input'' might be my idea of ``an extension'' or ``support
-for traditional practice''.
-
-@item
-If you are an experienced user of one of the languages GCC supports, your
-suggestions for improvement of GCC are welcome in any case.
-@end itemize
-
-@node Bug Lists,Bug Reporting,Bug Criteria,Bugs
-@section Where to Report Bugs
-@cindex bug report mailing lists
-@kindex gcc-bugs@@gcc.gnu.org or bug-gcc@@gnu.org
-Send bug reports for the GNU Compiler Collection to
-@email{gcc-bugs@@gcc.gnu.org}. In accordance with the GNU-wide
-convention, in which bug reports for tool ``foo'' are sent
-to @samp{bug-foo@@gnu.org}, the address @email{bug-gcc@@gnu.org}
-may also be used; it will forward to the address given above.
-
-Please read @uref{http://gcc.gnu.org/bugs.html} for additional and/or
-more up-to-date bug reporting instructions before you post a bug report.
-
-@node Bug Reporting,gccbug,Bug Lists,Bugs
-@section How to Report Bugs
-@cindex compiler bugs, reporting
-
-The fundamental principle of reporting bugs usefully is this:
-@strong{report all the facts}. If you are not sure whether to state a
-fact or leave it out, state it!
-
-Often people omit facts because they think they know what causes the
-problem and they conclude that some details don't matter. Thus, you might
-assume that the name of the variable you use in an example does not matter.
-Well, probably it doesn't, but one cannot be sure. Perhaps the bug is a
-stray memory reference which happens to fetch from the location where that
-name is stored in memory; perhaps, if the name were different, the contents
-of that location would fool the compiler into doing the right thing despite
-the bug. Play it safe and give a specific, complete example. That is the
-easiest thing for you to do, and the most helpful.
-
-Keep in mind that the purpose of a bug report is to enable someone to
-fix the bug if it is not known. It isn't very important what happens if
-the bug is already known. Therefore, always write your bug reports on
-the assumption that the bug is not known.
-
-Sometimes people give a few sketchy facts and ask, ``Does this ring a
-bell?'' This cannot help us fix a bug, so it is basically useless. We
-respond by asking for enough details to enable us to investigate.
-You might as well expedite matters by sending them to begin with.
-
-Try to make your bug report self-contained. If we have to ask you for
-more information, it is best if you include all the previous information
-in your response, as well as the information that was missing.
-
-Please report each bug in a separate message. This makes it easier for
-us to track which bugs have been fixed and to forward your bugs reports
-to the appropriate maintainer.
-
-To enable someone to investigate the bug, you should include all these
-things:
-
-@itemize @bullet
-@item
-The version of GCC@. You can get this by running it with the
-@option{-v} option.
-
-Without this, we won't know whether there is any point in looking for
-the bug in the current version of GCC@.
-
-@item
-A complete input file that will reproduce the bug. If the bug is in the
-C preprocessor, send a source file and any header files that it
-requires. If the bug is in the compiler proper (@file{cc1}), send the
-preprocessor output generated by adding @option{-save-temps} to the
-compilation command (@pxref{Debugging Options}). When you do this, use
-the same @option{-I}, @option{-D} or @option{-U} options that you used in
-actual compilation. Then send the @var{input}.i or @var{input}.ii files
-generated.
-
-A single statement is not enough of an example. In order to compile it,
-it must be embedded in a complete file of compiler input; and the bug
-might depend on the details of how this is done.
-
-Without a real example one can compile, all anyone can do about your bug
-report is wish you luck. It would be futile to try to guess how to
-provoke the bug. For example, bugs in register allocation and reloading
-frequently depend on every little detail of the function they happen in.
-
-Even if the input file that fails comes from a GNU program, you should
-still send the complete test case. Don't ask the GCC maintainers to
-do the extra work of obtaining the program in question---they are all
-overworked as it is. Also, the problem may depend on what is in the
-header files on your system; it is unreliable for the GCC maintainers
-to try the problem with the header files available to them. By sending
-CPP output, you can eliminate this source of uncertainty and save us
-a certain percentage of wild goose chases.
-
-@item
-The command arguments you gave GCC to compile that example
-and observe the bug. For example, did you use @option{-O}? To guarantee
-you won't omit something important, list all the options.
-
-If we were to try to guess the arguments, we would probably guess wrong
-and then we would not encounter the bug.
-
-@item
-The type of machine you are using, and the operating system name and
-version number.
-
-@item
-The operands you gave to the @code{configure} command when you installed
-the compiler.
-
-@item
-A complete list of any modifications you have made to the compiler
-source. (We don't promise to investigate the bug unless it happens in
-an unmodified compiler. But if you've made modifications and don't tell
-us, then you are sending us on a wild goose chase.)
-
-Be precise about these changes. A description in English is not
-enough---send a context diff for them.
-
-Adding files of your own (such as a machine description for a machine we
-don't support) is a modification of the compiler source.
-
-@item
-Details of any other deviations from the standard procedure for installing
-GCC@.
-
-@item
-A description of what behavior you observe that you believe is
-incorrect. For example, ``The compiler gets a fatal signal,'' or,
-``The assembler instruction at line 208 in the output is incorrect.''
-
-Of course, if the bug is that the compiler gets a fatal signal, then one
-can't miss it. But if the bug is incorrect output, the maintainer might
-not notice unless it is glaringly wrong. None of us has time to study
-all the assembler code from a 50-line C program just on the chance that
-one instruction might be wrong. We need @emph{you} to do this part!
-
-Even if the problem you experience is a fatal signal, you should still
-say so explicitly. Suppose something strange is going on, such as, your
-copy of the compiler is out of synch, or you have encountered a bug in
-the C library on your system. (This has happened!) Your copy might
-crash and the copy here would not. If you @i{said} to expect a crash,
-then when the compiler here fails to crash, we would know that the bug
-was not happening. If you don't say to expect a crash, then we would
-not know whether the bug was happening. We would not be able to draw
-any conclusion from our observations.
-
-If the problem is a diagnostic when compiling GCC with some other
-compiler, say whether it is a warning or an error.
-
-Often the observed symptom is incorrect output when your program is run.
-Sad to say, this is not enough information unless the program is short
-and simple. None of us has time to study a large program to figure out
-how it would work if compiled correctly, much less which line of it was
-compiled wrong. So you will have to do that. Tell us which source line
-it is, and what incorrect result happens when that line is executed. A
-person who understands the program can find this as easily as finding a
-bug in the program itself.
-
-@item
-If you send examples of assembler code output from GCC,
-please use @option{-g} when you make them. The debugging information
-includes source line numbers which are essential for correlating the
-output with the input.
-
-@item
-If you wish to mention something in the GCC source, refer to it by
-context, not by line number.
-
-The line numbers in the development sources don't match those in your
-sources. Your line numbers would convey no useful information to the
-maintainers.
-
-@item
-Additional information from a debugger might enable someone to find a
-problem on a machine which he does not have available. However, you
-need to think when you collect this information if you want it to have
-any chance of being useful.
-
-@cindex backtrace for bug reports
-For example, many people send just a backtrace, but that is never
-useful by itself. A simple backtrace with arguments conveys little
-about GCC because the compiler is largely data-driven; the same
-functions are called over and over for different RTL insns, doing
-different things depending on the details of the insn.
-
-Most of the arguments listed in the backtrace are useless because they
-are pointers to RTL list structure. The numeric values of the
-pointers, which the debugger prints in the backtrace, have no
-significance whatever; all that matters is the contents of the objects
-they point to (and most of the contents are other such pointers).
-
-In addition, most compiler passes consist of one or more loops that
-scan the RTL insn sequence. The most vital piece of information about
-such a loop---which insn it has reached---is usually in a local variable,
-not in an argument.
-
-@findex debug_rtx
-What you need to provide in addition to a backtrace are the values of
-the local variables for several stack frames up. When a local
-variable or an argument is an RTX, first print its value and then use
-the GDB command @code{pr} to print the RTL expression that it points
-to. (If GDB doesn't run on your machine, use your debugger to call
-the function @code{debug_rtx} with the RTX as an argument.) In
-general, whenever a variable is a pointer, its value is no use
-without the data it points to.
-@end itemize
-
-Here are some things that are not necessary:
-
-@itemize @bullet
-@item
-A description of the envelope of the bug.
-
-Often people who encounter a bug spend a lot of time investigating
-which changes to the input file will make the bug go away and which
-changes will not affect it.
-
-This is often time consuming and not very useful, because the way we
-will find the bug is by running a single example under the debugger with
-breakpoints, not by pure deduction from a series of examples. You might
-as well save your time for something else.
-
-Of course, if you can find a simpler example to report @emph{instead} of
-the original one, that is a convenience. Errors in the output will be
-easier to spot, running under the debugger will take less time, etc.
-Most GCC bugs involve just one function, so the most straightforward
-way to simplify an example is to delete all the function definitions
-except the one where the bug occurs. Those earlier in the file may be
-replaced by external declarations if the crucial function depends on
-them. (Exception: inline functions may affect compilation of functions
-defined later in the file.)
-
-However, simplification is not vital; if you don't want to do this,
-report the bug anyway and send the entire test case you used.
-
-@item
-In particular, some people insert conditionals @samp{#ifdef BUG} around
-a statement which, if removed, makes the bug not happen. These are just
-clutter; we won't pay any attention to them anyway. Besides, you should
-send us cpp output, and that can't have conditionals.
-
-@item
-A patch for the bug.
-
-A patch for the bug is useful if it is a good one. But don't omit the
-necessary information, such as the test case, on the assumption that a
-patch is all we need. We might see problems with your patch and decide
-to fix the problem another way, or we might not understand it at all.
-
-Sometimes with a program as complicated as GCC it is very hard to
-construct an example that will make the program follow a certain path
-through the code. If you don't send the example, we won't be able to
-construct one, so we won't be able to verify that the bug is fixed.
-
-And if we can't understand what bug you are trying to fix, or why your
-patch should be an improvement, we won't install it. A test case will
-help us to understand.
-
-@xref{Sending Patches}, for guidelines on how to make it easy for us to
-understand and install your patches.
-
-@item
-A guess about what the bug is or what it depends on.
-
-Such guesses are usually wrong. Even I can't guess right about such
-things without first using the debugger to find the facts.
-
-@item
-A core dump file.
-
-We have no way of examining a core dump for your type of machine
-unless we have an identical system---and if we do have one,
-we should be able to reproduce the crash ourselves.
-@end itemize
-
-@node gccbug,Sending Patches, Bug Reporting, Bugs
-@section The gccbug script
-@cindex gccbug script
-
-To simplify creation of bug reports, and to allow better tracking of
-reports, we use the GNATS bug tracking system. Part of that system is
-the @code{gccbug} script. This is a Unix shell script, so you need a
-shell to run it. It is normally installed in the same directory where
-@code{gcc} is installed.
-
-The gccbug script is derived from send-pr, @pxref{using
-send-pr,,Creating new Problem Reports,send-pr,Reporting Problems}. When
-invoked, it starts a text editor so you can fill out the various fields
-of the report. When the you quit the editor, the report is automatically
-send to the bug reporting address.
-
-A number of fields in this bug report form are specific to GCC, and are
-explained at @uref{http://gcc.gnu.org/gnats.html}.
-
-@node Sending Patches,, gccbug, Bugs
-@section Sending Patches for GCC
-
-If you would like to write bug fixes or improvements for the GNU C
-compiler, that is very helpful. Send suggested fixes to the patches
-mailing list, @email{gcc-patches@@gcc.gnu.org}.
-
-Please follow these guidelines so we can study your patches efficiently.
-If you don't follow these guidelines, your information might still be
-useful, but using it will take extra work. Maintaining GCC is a lot
-of work in the best of circumstances, and we can't keep up unless you do
-your best to help.
-
-@itemize @bullet
-@item
-Send an explanation with your changes of what problem they fix or what
-improvement they bring about. For a bug fix, just include a copy of the
-bug report, and explain why the change fixes the bug.
-
-(Referring to a bug report is not as good as including it, because then
-we will have to look it up, and we have probably already deleted it if
-we've already fixed the bug.)
-
-@item
-Always include a proper bug report for the problem you think you have
-fixed. We need to convince ourselves that the change is right before
-installing it. Even if it is right, we might have trouble judging it if
-we don't have a way to reproduce the problem.
-
-@item
-Include all the comments that are appropriate to help people reading the
-source in the future understand why this change was needed.
-
-@item
-Don't mix together changes made for different reasons.
-Send them @emph{individually}.
-
-If you make two changes for separate reasons, then we might not want to
-install them both. We might want to install just one. If you send them
-all jumbled together in a single set of diffs, we have to do extra work
-to disentangle them---to figure out which parts of the change serve
-which purpose. If we don't have time for this, we might have to ignore
-your changes entirely.
-
-If you send each change as soon as you have written it, with its own
-explanation, then the two changes never get tangled up, and we can
-consider each one properly without any extra work to disentangle them.
-
-Ideally, each change you send should be impossible to subdivide into
-parts that we might want to consider separately, because each of its
-parts gets its motivation from the other parts.
-
-@item
-Send each change as soon as that change is finished. Sometimes people
-think they are helping us by accumulating many changes to send them all
-together. As explained above, this is absolutely the worst thing you
-could do.
-
-Since you should send each change separately, you might as well send it
-right away. That gives us the option of installing it immediately if it
-is important.
-
-@item
-Use @samp{diff -c} to make your diffs. Diffs without context are hard
-for us to install reliably. More than that, they make it hard for us to
-study the diffs to decide whether we want to install them. Unidiff
-format is better than contextless diffs, but not as easy to read as
-@option{-c} format.
-
-If you have GNU diff, use @samp{diff -cp}, which shows the name of the
-function that each change occurs in.
-
-@item
-Write the change log entries for your changes. We get lots of changes,
-and we don't have time to do all the change log writing ourselves.
-
-Read the @file{ChangeLog} file to see what sorts of information to put
-in, and to learn the style that we use. The purpose of the change log
-is to show people where to find what was changed. So you need to be
-specific about what functions you changed; in large functions, it's
-often helpful to indicate where within the function the change was.
-
-On the other hand, once you have shown people where to find the change,
-you need not explain its purpose. Thus, if you add a new function, all
-you need to say about it is that it is new. If you feel that the
-purpose needs explaining, it probably does---but the explanation will be
-much more useful if you put it in comments in the code.
-
-If you would like your name to appear in the header line for who made
-the change, send us the header line.
-
-@item
-When you write the fix, keep in mind that we can't install a change that
-would break other systems.
-
-People often suggest fixing a problem by changing machine-independent
-files such as @file{toplev.c} to do something special that a particular
-system needs. Sometimes it is totally obvious that such changes would
-break GCC for almost all users. We can't possibly make a change like
-that. At best it might tell us how to write another patch that would
-solve the problem acceptably.
-
-Sometimes people send fixes that @emph{might} be an improvement in
-general---but it is hard to be sure of this. It's hard to install
-such changes because we have to study them very carefully. Of course,
-a good explanation of the reasoning by which you concluded the change
-was correct can help convince us.
-
-The safest changes are changes to the configuration files for a
-particular machine. These are safe because they can't create new bugs
-on other machines.
-
-Please help us keep up with the workload by designing the patch in a
-form that is good to install.
-@end itemize
-
-@node Service
-@chapter How To Get Help with GCC
-
-If you need help installing, using or changing GCC, there are two
-ways to find it:
-
-@itemize @bullet
-@item
-Send a message to a suitable network mailing list. First try
-@email{gcc-help@@gcc.gnu.org} (for help installing or using GCC), and if
-that brings no response, try @email{gcc@@gcc.gnu.org}. For help
-changing GCC, ask @email{gcc@@gcc.gnu.org}. If you think you have found
-a bug in GCC, please report it following the instructions at
-@pxref{Bug Reporting}.
-
-@item
-Look in the service directory for someone who might help you for a fee.
-The service directory is found at
-@uref{http://www.gnu.org/prep/service.html}.
-@end itemize
-
-@c For further information, see
-@c @uref{http://gcc.gnu.org/cgi-bin/fom.cgi?file=12}.
-@c FIXME: this URL may be too volatile, this FAQ entry needs to move to
-@c the regular web pages before we can uncomment the reference.
-
-@node Contributing
-@chapter Contributing to GCC Development
-
-If you would like to help pretest GCC releases to assure they work well,
-our current development sources are available by CVS (see
-@uref{http://gcc.gnu.org/cvs.html}). Source and binary snapshots are
-also available for FTP; see @uref{http://gcc.gnu.org/snapshots.html}.
-
-If you would like to work on improvements to GCC, please read
-@uref{http://gcc.gnu.org/contribute.html} and
-@uref{http://gcc.gnu.org/contributewhy.html} for information on how to
-make useful contributions and avoid duplication of effort. Suggested
-projects are listed at @uref{http://gcc.gnu.org/projects/}.
-
-@node VMS
-@chapter Using GCC on VMS
-
-@c prevent bad page break with this line
-Here is how to use GCC on VMS@.
-
-@menu
-* Include Files and VMS:: Where the preprocessor looks for the include files.
-* Global Declarations:: How to do globaldef, globalref and globalvalue with
- GCC.
-* VMS Misc:: Misc information.
-@end menu
-
-@node Include Files and VMS
-@section Include Files and VMS
-
-@cindex include files and VMS
-@cindex VMS and include files
-@cindex header files and VMS
-Due to the differences between the filesystems of Unix and VMS, GCC
-attempts to translate file names in @samp{#include} into names that VMS
-will understand. The basic strategy is to prepend a prefix to the
-specification of the include file, convert the whole filename to a VMS
-filename, and then try to open the file. GCC tries various prefixes
-one by one until one of them succeeds:
-
-@enumerate
-@item
-The first prefix is the @samp{GNU_CC_INCLUDE:} logical name: this is
-where GNU C header files are traditionally stored. If you wish to store
-header files in non-standard locations, then you can assign the logical
-@samp{GNU_CC_INCLUDE} to be a search list, where each element of the
-list is suitable for use with a rooted logical.
-
-@item
-The next prefix tried is @samp{SYS$SYSROOT:[SYSLIB.]}. This is where
-VAX-C header files are traditionally stored.
-
-@item
-If the include file specification by itself is a valid VMS filename, the
-preprocessor then uses this name with no prefix in an attempt to open
-the include file.
-
-@item
-If the file specification is not a valid VMS filename (i.e.@: does not
-contain a device or a directory specifier, and contains a @samp{/}
-character), the preprocessor tries to convert it from Unix syntax to
-VMS syntax.
-
-Conversion works like this: the first directory name becomes a device,
-and the rest of the directories are converted into VMS-format directory
-names. For example, the name @file{X11/foobar.h} is
-translated to @file{X11:[000000]foobar.h} or @file{X11:foobar.h},
-whichever one can be opened. This strategy allows you to assign a
-logical name to point to the actual location of the header files.
-
-@item
-If none of these strategies succeeds, the @samp{#include} fails.
-@end enumerate
-
-Include directives of the form:
-
-@example
-#include foobar
-@end example
-
-@noindent
-are a common source of incompatibility between VAX-C and GCC@. VAX-C
-treats this much like a standard @code{#include <foobar.h>} directive.
-That is incompatible with the ISO C behavior implemented by GCC: to
-expand the name @code{foobar} as a macro. Macro expansion should
-eventually yield one of the two standard formats for @code{#include}:
-
-@example
-#include "@var{file}"
-#include <@var{file}>
-@end example
-
-If you have this problem, the best solution is to modify the source to
-convert the @code{#include} directives to one of the two standard forms.
-That will work with either compiler. If you want a quick and dirty fix,
-define the file names as macros with the proper expansion, like this:
-
-@example
-#define stdio <stdio.h>
-@end example
-
-@noindent
-This will work, as long as the name doesn't conflict with anything else
-in the program.
-
-Another source of incompatibility is that VAX-C assumes that:
-
-@example
-#include "foobar"
-@end example
-
-@noindent
-is actually asking for the file @file{foobar.h}. GCC does not
-make this assumption, and instead takes what you ask for literally;
-it tries to read the file @file{foobar}. The best way to avoid this
-problem is to always specify the desired file extension in your include
-directives.
-
-GCC for VMS is distributed with a set of include files that is
-sufficient to compile most general purpose programs. Even though the
-GCC distribution does not contain header files to define constants
-and structures for some VMS system-specific functions, there is no
-reason why you cannot use GCC with any of these functions. You first
-may have to generate or create header files, either by using the public
-domain utility @code{UNSDL} (which can be found on a DECUS tape), or by
-extracting the relevant modules from one of the system macro libraries,
-and using an editor to construct a C header file.
-
-A @code{#include} file name cannot contain a DECNET node name. The
-preprocessor reports an I/O error if you attempt to use a node name,
-whether explicitly, or implicitly via a logical name.
-
-@node Global Declarations
-@section Global Declarations and VMS
-
-@findex GLOBALREF
-@findex GLOBALDEF
-@findex GLOBALVALUEDEF
-@findex GLOBALVALUEREF
-GCC does not provide the @code{globalref}, @code{globaldef} and
-@code{globalvalue} keywords of VAX-C@. You can get the same effect with
-an obscure feature of GAS, the GNU assembler. (This requires GAS
-version 1.39 or later.) The following macros allow you to use this
-feature in a fairly natural way:
-
-@smallexample
-#ifdef __GNUC__
-#define GLOBALREF(TYPE,NAME) \
- TYPE NAME \
- asm ("_$$PsectAttributes_GLOBALSYMBOL$$" #NAME)
-#define GLOBALDEF(TYPE,NAME,VALUE) \
- TYPE NAME \
- asm ("_$$PsectAttributes_GLOBALSYMBOL$$" #NAME) \
- = VALUE
-#define GLOBALVALUEREF(TYPE,NAME) \
- const TYPE NAME[1] \
- asm ("_$$PsectAttributes_GLOBALVALUE$$" #NAME)
-#define GLOBALVALUEDEF(TYPE,NAME,VALUE) \
- const TYPE NAME[1] \
- asm ("_$$PsectAttributes_GLOBALVALUE$$" #NAME) \
- = @{VALUE@}
-#else
-#define GLOBALREF(TYPE,NAME) \
- globalref TYPE NAME
-#define GLOBALDEF(TYPE,NAME,VALUE) \
- globaldef TYPE NAME = VALUE
-#define GLOBALVALUEDEF(TYPE,NAME,VALUE) \
- globalvalue TYPE NAME = VALUE
-#define GLOBALVALUEREF(TYPE,NAME) \
- globalvalue TYPE NAME
-#endif
-@end smallexample
-
-@noindent
-(The @code{_$$PsectAttributes_GLOBALSYMBOL} prefix at the start of the
-name is removed by the assembler, after it has modified the attributes
-of the symbol). These macros are provided in the VMS binaries
-distribution in a header file @file{GNU_HACKS.H}. An example of the
-usage is:
-
-@example
-GLOBALREF (int, ijk);
-GLOBALDEF (int, jkl, 0);
-@end example
-
-The macros @code{GLOBALREF} and @code{GLOBALDEF} cannot be used
-straightforwardly for arrays, since there is no way to insert the array
-dimension into the declaration at the right place. However, you can
-declare an array with these macros if you first define a typedef for the
-array type, like this:
-
-@example
-typedef int intvector[10];
-GLOBALREF (intvector, foo);
-@end example
-
-Array and structure initializers will also break the macros; you can
-define the initializer to be a macro of its own, or you can expand the
-@code{GLOBALDEF} macro by hand. You may find a case where you wish to
-use the @code{GLOBALDEF} macro with a large array, but you are not
-interested in explicitly initializing each element of the array. In
-such cases you can use an initializer like: @code{@{0,@}}, which will
-initialize the entire array to @code{0}.
-
-A shortcoming of this implementation is that a variable declared with
-@code{GLOBALVALUEREF} or @code{GLOBALVALUEDEF} is always an array. For
-example, the declaration:
-
-@example
-GLOBALVALUEREF(int, ijk);
-@end example
-
-@noindent
-declares the variable @code{ijk} as an array of type @code{int [1]}.
-This is done because a globalvalue is actually a constant; its ``value''
-is what the linker would normally consider an address. That is not how
-an integer value works in C, but it is how an array works. So treating
-the symbol as an array name gives consistent results---with the
-exception that the value seems to have the wrong type. @strong{Don't
-try to access an element of the array.} It doesn't have any elements.
-The array ``address'' may not be the address of actual storage.
-
-The fact that the symbol is an array may lead to warnings where the
-variable is used. Insert type casts to avoid the warnings. Here is an
-example; it takes advantage of the ISO C feature allowing macros that
-expand to use the same name as the macro itself.
-
-@example
-GLOBALVALUEREF (int, ss$_normal);
-GLOBALVALUEDEF (int, xyzzy,123);
-#ifdef __GNUC__
-#define ss$_normal ((int) ss$_normal)
-#define xyzzy ((int) xyzzy)
-#endif
-@end example
-
-Don't use @code{globaldef} or @code{globalref} with a variable whose
-type is an enumeration type; this is not implemented. Instead, make the
-variable an integer, and use a @code{globalvaluedef} for each of the
-enumeration values. An example of this would be:
-
-@example
-#ifdef __GNUC__
-GLOBALDEF (int, color, 0);
-GLOBALVALUEDEF (int, RED, 0);
-GLOBALVALUEDEF (int, BLUE, 1);
-GLOBALVALUEDEF (int, GREEN, 3);
-#else
-enum globaldef color @{RED, BLUE, GREEN = 3@};
-#endif
-@end example
-
-@node VMS Misc
-@section Other VMS Issues
-
-@cindex exit status and VMS
-@cindex return value of @code{main}
-@cindex @code{main} and the exit status
-GCC automatically arranges for @code{main} to return 1 by default if
-you fail to specify an explicit return value. This will be interpreted
-by VMS as a status code indicating a normal successful completion.
-Version 1 of GCC did not provide this default.
-
-GCC on VMS works only with the GNU assembler, GAS@. You need version
-1.37 or later of GAS in order to produce value debugging information for
-the VMS debugger. Use the ordinary VMS linker with the object files
-produced by GAS@.
-
-@cindex shared VMS run time system
-@cindex @file{VAXCRTL}
-Under previous versions of GCC, the generated code would occasionally
-give strange results when linked to the sharable @file{VAXCRTL} library.
-Now this should work.
-
-A caveat for use of @code{const} global variables: the @code{const}
-modifier must be specified in every external declaration of the variable
-in all of the source files that use that variable. Otherwise the linker
-will issue warnings about conflicting attributes for the variable. Your
-program will still work despite the warnings, but the variable will be
-placed in writable storage.
-
-@cindex name augmentation
-@cindex case sensitivity and VMS
-@cindex VMS and case sensitivity
-Although the VMS linker does distinguish between upper and lower case
-letters in global symbols, most VMS compilers convert all such symbols
-into upper case and most run-time library routines also have upper case
-names. To be able to reliably call such routines, GCC (by means of
-the assembler GAS) converts global symbols into upper case like other
-VMS compilers. However, since the usual practice in C is to distinguish
-case, GCC (via GAS) tries to preserve usual C behavior by augmenting
-each name that is not all lower case. This means truncating the name
-to at most 23 characters and then adding more characters at the end
-which encode the case pattern of those 23. Names which contain at
-least one dollar sign are an exception; they are converted directly into
-upper case without augmentation.
-
-Name augmentation yields bad results for programs that use precompiled
-libraries (such as Xlib) which were generated by another compiler. You
-can use the compiler option @samp{/NOCASE_HACK} to inhibit augmentation;
-it makes external C functions and variables case-independent as is usual
-on VMS@. Alternatively, you could write all references to the functions
-and variables in such libraries using lower case; this will work on VMS,
-but is not portable to other systems. The compiler option @samp{/NAMES}
-also provides control over global name handling.
-
-Function and variable names are handled somewhat differently with G++.
-The GNU C++ compiler performs @dfn{name mangling} on function
-names, which means that it adds information to the function name to
-describe the data types of the arguments that the function takes. One
-result of this is that the name of a function can become very long.
-Since the VMS linker only recognizes the first 31 characters in a name,
-special action is taken to ensure that each function and variable has a
-unique name that can be represented in 31 characters.
-
-If the name (plus a name augmentation, if required) is less than 32
-characters in length, then no special action is performed. If the name
-is longer than 31 characters, the assembler (GAS) will generate a
-hash string based upon the function name, truncate the function name to
-23 characters, and append the hash string to the truncated name. If the
-@samp{/VERBOSE} compiler option is used, the assembler will print both
-the full and truncated names of each symbol that is truncated.
-
-The @samp{/NOCASE_HACK} compiler option should not be used when you are
-compiling programs that use libg++. libg++ has several instances of
-objects (i.e. @code{Filebuf} and @code{filebuf}) which become
-indistinguishable in a case-insensitive environment. This leads to
-cases where you need to inhibit augmentation selectively (if you were
-using libg++ and Xlib in the same program, for example). There is no
-special feature for doing this, but you can get the result by defining a
-macro for each mixed case symbol for which you wish to inhibit
-augmentation. The macro should expand into the lower case equivalent of
-itself. For example:
-
-@example
-#define StuDlyCapS studlycaps
-@end example
-
-These macro definitions can be placed in a header file to minimize the
-number of changes to your source code.
-
-@node Makefile
-@chapter Makefile Targets
-@cindex makefile targets
-@cindex targets, makefile
-
-@table @code
-@item all
-This is the default target. Depending on what your build/host/target
-configuration is, it coordinates all the things that need to be built.
-
-@item doc
-Produce info-formatted documentation. Also, @code{make dvi} is
-available for DVI-formatted documentation, and @code{make
-generated-manpages} to generate man pages.
-
-@item mostlyclean
-Delete the files made while building the compiler.
-
-@item clean
-That, and all the other files built by @code{make all}.
-
-@item distclean
-That, and all the files created by @code{configure}.
-
-@item extraclean
-That, and any temporary or intermediate files, like emacs backup files.
-
-@item maintainer-clean
-Distclean plus any file that can be generated from other files. Note
-that additional tools may be required beyond what is normally needed to
-build gcc.
-
-@item install
-Installs gcc.
-
-@item uninstall
-Deletes installed files.
-
-@item check
-Run the testsuite. This creates a @file{testsuite} subdirectory that
-has various @file{.sum} and @file{.log} files containing the results of
-the testing. You can run subsets with, for example, @code{make check-gcc}.
-You can specify specific tests by setting RUNTESTFLAGS to be the name
-of the @file{.exp} file, optionally followed by (for some tests) an equals
-and a file wildcard, like:
-
-@example
-make check-gcc RUNTESTFLAGS="execute.exp=19980413-*"
-@end example
-
-Note that running the testsuite may require additional tools be
-installed, such as TCL or dejagnu.
-
-@item bootstrap
-Builds gcc three times---once with the native compiler, once with the
-native-built compiler it just built, and once with the compiler it built
-the second time. In theory, the last two should produce the same
-results, which @code{make compare} can check. Each step of this process
-is called a ``stage'', and the results of each stage @var{N}
-(@var{N} = 1@dots{}3) are copied to a subdirectory @file{stage@var{N}/}.
-
-@item bootstrap-lean
-Like @code{bootstrap}, except that the various stages are removed once
-they're no longer needed. This saves disk space.
-
-@item bubblestrap
-Once bootstrapped, this incrementally rebuilds each of the three stages,
-one at a time. It does this by ``bubbling'' the stages up from their
-subdirectories, rebuilding them, and copying them back to their
-subdirectories. This will allow you to, for example, quickly rebuild a
-bootstrapped compiler after changing the sources, without having to do a
-full bootstrap.
-
-@item quickstrap
-Rebuilds the most recently built stage. Since each stage requires
-special invocation, using this target means you don't have to keep track
-of which stage you're on or what invocation that stage needs.
-
-@item cleanstrap
-Removed everything (@code{make clean}) and rebuilds (@code{make bootstrap}).
-
-@item stage@var{N} (@var{N} = 1@dots{}4)
-For each stage, moves the appropriate files to the @file{stage@var{N}}
-subdirectory.
-
-@item unstage@var{N} (@var{N} = 1@dots{}4)
-Undoes the corresponding @code{stage@var{N}}.
-
-@item restage@var{N} (@var{N} = 1@dots{}4)
-Undoes the corresponding @code{stage@var{N}} and rebuilds it with the
-appropriate flags.
-
-@item compare
-Compares the results of stages 2 and 3. This ensures that the compiler
-is running properly, since it should produce the same object files
-regardless of how it itself was compiled.
-
-@end table
-
-@end ifset
-
-@ifset INTERNALS
-@node Portability
-@chapter GCC and Portability
-@cindex portability
-@cindex GCC and portability
-
-The main goal of GCC was to make a good, fast compiler for machines in
-the class that the GNU system aims to run on: 32-bit machines that address
-8-bit bytes and have several general registers. Elegance, theoretical
-power and simplicity are only secondary.
-
-GCC gets most of the information about the target machine from a machine
-description which gives an algebraic formula for each of the machine's
-instructions. This is a very clean way to describe the target. But when
-the compiler needs information that is difficult to express in this
-fashion, I have not hesitated to define an ad-hoc parameter to the machine
-description. The purpose of portability is to reduce the total work needed
-on the compiler; it was not of interest for its own sake.
-
-@cindex endianness
-@cindex autoincrement addressing, availability
-@findex abort
-GCC does not contain machine dependent code, but it does contain code
-that depends on machine parameters such as endianness (whether the most
-significant byte has the highest or lowest address of the bytes in a word)
-and the availability of autoincrement addressing. In the RTL-generation
-pass, it is often necessary to have multiple strategies for generating code
-for a particular kind of syntax tree, strategies that are usable for different
-combinations of parameters. Often I have not tried to address all possible
-cases, but only the common ones or only the ones that I have encountered.
-As a result, a new target may require additional strategies. You will know
-if this happens because the compiler will call @code{abort}. Fortunately,
-the new strategies can be added in a machine-independent fashion, and will
-affect only the target machines that need them.
-@end ifset
-
-@ifset INTERNALS
-@node Interface
-@chapter Interfacing to GCC Output
-@cindex interfacing to GCC output
-@cindex run-time conventions
-@cindex function call conventions
-@cindex conventions, run-time
-
-GCC is normally configured to use the same function calling convention
-normally in use on the target system. This is done with the
-machine-description macros described (@pxref{Target Macros}).
-
-@cindex unions, returning
-@cindex structures, returning
-@cindex returning structures and unions
-However, returning of structure and union values is done differently on
-some target machines. As a result, functions compiled with PCC
-returning such types cannot be called from code compiled with GCC,
-and vice versa. This does not cause trouble often because few Unix
-library routines return structures or unions.
-
-GCC code returns structures and unions that are 1, 2, 4 or 8 bytes
-long in the same registers used for @code{int} or @code{double} return
-values. (GCC typically allocates variables of such types in
-registers also.) Structures and unions of other sizes are returned by
-storing them into an address passed by the caller (usually in a
-register). The machine-description macros @code{STRUCT_VALUE} and
-@code{STRUCT_INCOMING_VALUE} tell GCC where to pass this address.
-
-By contrast, PCC on most target machines returns structures and unions
-of any size by copying the data into an area of static storage, and then
-returning the address of that storage as if it were a pointer value.
-The caller must copy the data from that memory area to the place where
-the value is wanted. This is slower than the method used by GCC, and
-fails to be reentrant.
-
-On some target machines, such as RISC machines and the 80386, the
-standard system convention is to pass to the subroutine the address of
-where to return the value. On these machines, GCC has been
-configured to be compatible with the standard compiler, when this method
-is used. It may not be compatible for structures of 1, 2, 4 or 8 bytes.
-
-@cindex argument passing
-@cindex passing arguments
-GCC uses the system's standard convention for passing arguments. On
-some machines, the first few arguments are passed in registers; in
-others, all are passed on the stack. It would be possible to use
-registers for argument passing on any machine, and this would probably
-result in a significant speedup. But the result would be complete
-incompatibility with code that follows the standard convention. So this
-change is practical only if you are switching to GCC as the sole C
-compiler for the system. We may implement register argument passing on
-certain machines once we have a complete GNU system so that we can
-compile the libraries with GCC@.
-
-On some machines (particularly the Sparc), certain types of arguments
-are passed ``by invisible reference''. This means that the value is
-stored in memory, and the address of the memory location is passed to
-the subroutine.
-
-@cindex @code{longjmp} and automatic variables
-If you use @code{longjmp}, beware of automatic variables. ISO C says that
-automatic variables that are not declared @code{volatile} have undefined
-values after a @code{longjmp}. And this is all GCC promises to do,
-because it is very difficult to restore register variables correctly, and
-one of GCC's features is that it can put variables in registers without
-your asking it to.
-
-If you want a variable to be unaltered by @code{longjmp}, and you don't
-want to write @code{volatile} because old C compilers don't accept it,
-just take the address of the variable. If a variable's address is ever
-taken, even if just to compute it and ignore it, then the variable cannot
-go in a register:
-
-@example
-@{
- int careful;
- &careful;
- @dots{}
-@}
-@end example
-
-@cindex arithmetic libraries
-@cindex math libraries
-@opindex msoft-float
-Code compiled with GCC may call certain library routines. Most of
-them handle arithmetic for which there are no instructions. This
-includes multiply and divide on some machines, and floating point
-operations on any machine for which floating point support is disabled
-with @option{-msoft-float}. Some standard parts of the C library, such as
-@code{bcopy} or @code{memcpy}, are also called automatically. The usual
-function call interface is used for calling the library routines.
-
-Some of these routines can be defined in mostly machine-independent C;
-they appear in @file{libgcc2.c}. Others must be hand-written in
-assembly language for each processor. Wherever they are defined, they
-are compiled into the support library, @file{libgcc.a}, which is
-automatically searched when you link programs with GCC@.
-@end ifset
-
-@ifset INTERNALS
-@node Passes
-@chapter Passes and Files of the Compiler
-@cindex passes and files of the compiler
-@cindex files and passes of the compiler
-@cindex compiler passes and files
-
-@cindex top level of compiler
-The overall control structure of the compiler is in @file{toplev.c}. This
-file is responsible for initialization, decoding arguments, opening and
-closing files, and sequencing the passes.
-
-@cindex parsing pass
-The parsing pass is invoked only once, to parse the entire input. A
-high level tree representation is then generated from the input,
-one function at a time. This tree code is then transformed into RTL
-intermediate code, and processed. The files involved in transforming
-the trees into RTL are @file{expr.c}, @file{expmed.c}, and
-@file{stmt.c}.
-@c Note, the above files aren't strictly the only files involved. It's
-@c all over the place (function.c, final.c,etc). However, those are
-@c the files that are supposed to be directly involved, and have
-@c their purpose listed as such, so i've only listed them.
-The order of trees that are processed, is not
-necessarily the same order they are generated from
-the input, due to deferred inlining, and other considerations.
-
-@findex rest_of_compilation
-@findex rest_of_decl_compilation
-Each time the parsing pass reads a complete function definition or
-top-level declaration, it calls either the function
-@code{rest_of_compilation}, or the function
-@code{rest_of_decl_compilation} in @file{toplev.c}, which are
-responsible for all further processing necessary, ending with output of
-the assembler language. All other compiler passes run, in sequence,
-within @code{rest_of_compilation}. When that function returns from
-compiling a function definition, the storage used for that function
-definition's compilation is entirely freed, unless it is an inline
-function, or was deferred for some reason (this can occur in
-templates, for example).
-@ifset USING
-(@pxref{Inline,,An Inline Function is As Fast As a Macro}).
-@end ifset
-@ifclear USING
-(@pxref{Inline,,An Inline Function is As Fast As a Macro,gcc.texi,Using GCC}).
-@end ifclear
-
-Here is a list of all the passes of the compiler and their source files.
-Also included is a description of where debugging dumps can be requested
-with @option{-d} options.
-
-@itemize @bullet
-@item
-Parsing. This pass reads the entire text of a function definition,
-constructing a high level tree representation. (Because of the semantic
-analysis that takes place during this pass, it does more than is
-formally considered to be parsing.)
-
-The tree representation does not entirely follow C syntax, because it is
-intended to support other languages as well.
-
-Language-specific data type analysis is also done in this pass, and every
-tree node that represents an expression has a data type attached.
-Variables are represented as declaration nodes.
-
-The language-independent source files for parsing are
-@file{stor-layout.c}, @file{fold-const.c}, and @file{tree.c}.
-There are also header files @file{tree.h} and @file{tree.def}
-which define the format of the tree representation.
-
-C Preprocessing, for language front ends, that want or require it, is
-performed by cpplib, which is covered in seperate documentation. In
-particular, the internals are covered in @xref{Top, ,Cpplib internals, cppinternals, Cpplib Internals}.
-
-
-@c Avoiding overfull is tricky here.
-The source files to parse C are
-@file{c-aux-info.c},
-@file{c-convert.c},
-@file{c-decl.c},
-@file{c-errors.c},
-@file{c-lang.c},
-@file{c-parse.in},
-and
-@file{c-typeck.c},
-along with a header file
-@file{c-tree.h}
-and some files shared with Objective-C and C++.
-
-The source files for parsing C++ are in @file{cp/}.
-They are @file{parse.y},
-@file{class.c},
-@file{cvt.c}, @file{decl.c}, @file{decl2.c},
-@file{except.c},
-@file{expr.c}, @file{init.c}, @file{lex.c},
-@file{method.c}, @file{ptree.c},
-@file{search.c}, @file{spew.c},
-@file{semantics.c}, @file{tree.c},
-@file{typeck2.c}, and
-@file{typeck.c}, along with header files @file{cp-tree.def},
-@file{cp-tree.h}, and @file{decl.h}.
-
-The special source files for parsing Objective-C are in @file{objc/}.
-They are @file{objc-parse.y}, @file{objc-act.c}, @file{objc-tree.def}, and
-@file{objc-act.h}. Certain C-specific files are used for this as
-well.
-
-The files
-@file{c-common.c},
-@file{c-common.def},
-@file{c-dump.c},
-@file{c-format.c},
-@file{c-lex.c},
-@file{c-pragma.c},
-and
-@file{c-semantics.c},
-along with header files
-@file{c-common.h},
-@file{c-dump.h},
-@file{c-lex.h},
-and
-@file{c-pragma.h},
-are also used for all of the above languages.
-
-
-@cindex Tree optimization
-@item
-Tree optimization. This is the optimization of the tree
-representation, before converting into RTL code.
-
-@cindex inline on trees, automatic
-Currently, the main optimization performed here is tree-based
-inlining.
-This is implemented for C++ in @file{cp/optimize.c}. Note that
-tree based inlining turns off rtx based inlining (since it's more
-powerful, it would be a waste of time to do rtx based inlining in
-addition).
-The C front end currently does not perform tree based inlining.
-
-@cindex constant folding
-@cindex arithmetic simplifications
-@cindex simplifications, arithmetic
-Constant folding and some arithmetic simplifications are also done
-during this pass, on the tree representation.
-The routines that perform these tasks are located in @file{fold-const.c}.
-
-@cindex RTL generation
-@item
-RTL generation. This is the conversion of syntax tree into RTL code.
-
-@cindex target-parameter-dependent code
-This is where the bulk of target-parameter-dependent code is found,
-since often it is necessary for strategies to apply only when certain
-standard kinds of instructions are available. The purpose of named
-instruction patterns is to provide this information to the RTL
-generation pass.
-
-@cindex tail recursion optimization
-Optimization is done in this pass for @code{if}-conditions that are
-comparisons, boolean operations or conditional expressions. Tail
-recursion is detected at this time also. Decisions are made about how
-best to arrange loops and how to output @code{switch} statements.
-
-@c Avoiding overfull is tricky here.
-The source files for RTL generation include
-@file{stmt.c},
-@file{calls.c},
-@file{expr.c},
-@file{explow.c},
-@file{expmed.c},
-@file{function.c},
-@file{optabs.c}
-and @file{emit-rtl.c}.
-Also, the file
-@file{insn-emit.c}, generated from the machine description by the
-program @code{genemit}, is used in this pass. The header file
-@file{expr.h} is used for communication within this pass.
-
-@findex genflags
-@findex gencodes
-The header files @file{insn-flags.h} and @file{insn-codes.h},
-generated from the machine description by the programs @code{genflags}
-and @code{gencodes}, tell this pass which standard names are available
-for use and which patterns correspond to them.
-
-Aside from debugging information output, none of the following passes
-refers to the tree structure representation of the function (only
-part of which is saved).
-
-@cindex inline on rtx, automatic
-The decision of whether the function can and should be expanded inline
-in its subsequent callers is made at the end of rtl generation. The
-function must meet certain criteria, currently related to the size of
-the function and the types and number of parameters it has. Note that
-this function may contain loops, recursive calls to itself
-(tail-recursive functions can be inlined!), gotos, in short, all
-constructs supported by GCC@. The file @file{integrate.c} contains
-the code to save a function's rtl for later inlining and to inline that
-rtl when the function is called. The header file @file{integrate.h}
-is also used for this purpose.
-
-@opindex dr
-The option @option{-dr} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.rtl} to
-the input file name.
-
-@c Should the exception handling pass be talked about here?
-
-@cindex sibling call optimization
-@item
-Sibiling call optimization. This pass performs tail recursion
-elimination, and tail and sibling call optimizations. The purpose of
-these optimizations is to reduce the overhead of function calls,
-whenever possible.
-
-The source file of this pass is @file{sibcall.c}
-
-@opindex di
-The option @option{-di} causes a debugging dump of the RTL code after
-this pass is run. This dump file's name is made by appending
-@samp{.sibling} to the input file name.
-
-@cindex jump optimization
-@cindex unreachable code
-@cindex dead code
-@item
-Jump optimization. This pass simplifies jumps to the following
-instruction, jumps across jumps, and jumps to jumps. It deletes
-unreferenced labels and unreachable code, except that unreachable code
-that contains a loop is not recognized as unreachable in this pass.
-(Such loops are deleted later in the basic block analysis.) It also
-converts some code originally written with jumps into sequences of
-instructions that directly set values from the results of comparisons,
-if the machine has such instructions.
-
-Jump optimization is performed two or three times. The first time is
-immediately following RTL generation. The second time is after CSE,
-but only if CSE says repeated jump optimization is needed. The
-last time is right before the final pass. That time, cross-jumping
-and deletion of no-op move instructions are done together with the
-optimizations described above.
-
-The source file of this pass is @file{jump.c}.
-
-@opindex dj
-The option @option{-dj} causes a debugging dump of the RTL code after
-this pass is run for the first time. This dump file's name is made by
-appending @samp{.jump} to the input file name.
-
-
-@cindex register use analysis
-@item
-Register scan. This pass finds the first and last use of each
-register, as a guide for common subexpression elimination. Its source
-is in @file{regclass.c}.
-
-@cindex jump threading
-@item
-@opindex fthread-jumps
-Jump threading. This pass detects a condition jump that branches to an
-identical or inverse test. Such jumps can be @samp{threaded} through
-the second conditional test. The source code for this pass is in
-@file{jump.c}. This optimization is only performed if
-@option{-fthread-jumps} is enabled.
-
-@cindex SSA optimizations
-@cindex Single Static Assignment optimizations
-@opindex fssa
-@item
-Static Single Assignment (SSA) based optimization passes. The
-SSA conversion passes (to/from) are turned on by the @option{-fssa}
-option (it is also done automatically if you enable an SSA optimization pass).
-These passes utilize a form called Static Single Assignment. In SSA form,
-each variable (pseudo register) is only set once, giving you def-use
-and use-def chains for free, and enabling a lot more optimization
-passes to be run in linear time.
-Conversion to and from SSA form is handled by functions in
-@file{ssa.c}.
-
-@opindex de
-The option @option{-de} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.ssa} to
-the input file name.
-@itemize @bullet
-@cindex SSA DCE
-@cindex DCE, SSA based
-@cindex dead code elimination
-@opindex fdce
-@item
-SSA Aggressive Dead Code Elimination. Turned on by the @option{-fssa-dce}
-option. This pass performs elimination of code considered unnecessary because
-it has no externally visible effects on the program. It operates in
-linear time.
-
-@opindex dX
-The option @option{-dX} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.ssadce} to
-the input file name.
-@end itemize
-
-@cindex common subexpression elimination
-@cindex constant propagation
-@item
-Common subexpression elimination. This pass also does constant
-propagation. Its source files are @file{cse.c}, and @file{cselib.c}.
-If constant propagation causes conditional jumps to become
-unconditional or to become no-ops, jump optimization is run again when
-CSE is finished.
-
-@opindex ds
-The option @option{-ds} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.cse} to
-the input file name.
-
-@cindex global common subexpression elimination
-@cindex constant propagation
-@cindex copy propagation
-@item
-Global common subexpression elimination. This pass performs two
-different types of GCSE depending on whether you are optimizing for
-size or not (LCM based GCSE tends to increase code size for a gain in
-speed, while Morel-Renvoise based GCSE does not).
-When optimizing for size, GCSE is done using Morel-Renvoise Partial
-Redundancy Elimination, with the exception that it does not try to move
-invariants out of loops---that is left to the loop optimization pass.
-If MR PRE GCSE is done, code hoisting (aka unification) is also done, as
-well as load motion.
-If you are optimizing for speed, LCM (lazy code motion) based GCSE is
-done. LCM is based on the work of Knoop, Ruthing, and Steffen. LCM
-based GCSE also does loop invariant code motion. We also perform load
-and store motion when optimizing for speed.
-Regardless of which type of GCSE is used, the GCSE pass also performs
-global constant and copy propagation.
-
-The source file for this pass is @file{gcse.c}, and the LCM routines
-are in @file{lcm.c}.
-
-@opindex dG
-The option @option{-dG} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.gcse} to
-the input file name.
-
-@cindex loop optimization
-@cindex code motion
-@cindex strength-reduction
-@item
-Loop optimization. This pass moves constant expressions out of loops,
-and optionally does strength-reduction and loop unrolling as well.
-Its source files are @file{loop.c} and @file{unroll.c}, plus the header
-@file{loop.h} used for communication between them. Loop unrolling uses
-some functions in @file{integrate.c} and the header @file{integrate.h}.
-Loop dependency analysis routines are contained in @file{dependence.c}.
-
-@opindex dL
-The option @option{-dL} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.loop} to
-the input file name.
-
-@item
-@opindex frerun-cse-after-loop
-If @option{-frerun-cse-after-loop} was enabled, a second common
-subexpression elimination pass is performed after the loop optimization
-pass. Jump threading is also done again at this time if it was specified.
-
-@opindex dt
-The option @option{-dt} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.cse2} to
-the input file name.
-
-@cindex data flow analysis
-@cindex analysis, data flow
-@cindex basic blocks
-@item
-Data flow analysis (@file{flow.c}). This pass divides the program
-into basic blocks (and in the process deletes unreachable loops); then
-it computes which pseudo-registers are live at each point in the
-program, and makes the first instruction that uses a value point at
-the instruction that computed the value.
-
-@cindex autoincrement/decrement analysis
-This pass also deletes computations whose results are never used, and
-combines memory references with add or subtract instructions to make
-autoincrement or autodecrement addressing.
-
-@opindex df
-The option @option{-df} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.flow} to
-the input file name. If stupid register allocation is in use, this
-dump file reflects the full results of such allocation.
-
-@cindex instruction combination
-@item
-Instruction combination (@file{combine.c}). This pass attempts to
-combine groups of two or three instructions that are related by data
-flow into single instructions. It combines the RTL expressions for
-the instructions by substitution, simplifies the result using algebra,
-and then attempts to match the result against the machine description.
-
-@opindex dc
-The option @option{-dc} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.combine}
-to the input file name.
-
-@cindex if conversion
-@item
-If-conversion is a transformation that transforms control dependencies
-into data dependencies (IE it transforms conditional code into a
-single control stream).
-It is implemented in the file @file{ifcvt.c}.
-
-@opindex dE
-The option @option{-dE} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.ce} to
-the input file name.
-
-@cindex register movement
-@item
-Register movement (@file{regmove.c}). This pass looks for cases where
-matching constraints would force an instruction to need a reload, and
-this reload would be a register to register move. It then attempts
-to change the registers used by the instruction to avoid the move
-instruction.
-
-@opindex dN
-The option @option{-dN} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.regmove}
-to the input file name.
-
-@cindex instruction scheduling
-@cindex scheduling, instruction
-@item
-Instruction scheduling (@file{sched.c}). This pass looks for
-instructions whose output will not be available by the time that it is
-used in subsequent instructions. (Memory loads and floating point
-instructions often have this behavior on RISC machines). It re-orders
-instructions within a basic block to try to separate the definition and
-use of items that otherwise would cause pipeline stalls.
-
-Instruction scheduling is performed twice. The first time is immediately
-after instruction combination and the second is immediately after reload.
-
-@opindex dS
-The option @option{-dS} causes a debugging dump of the RTL code after this
-pass is run for the first time. The dump file's name is made by
-appending @samp{.sched} to the input file name.
-
-@cindex register class preference pass
-@item
-Register class preferencing. The RTL code is scanned to find out
-which register class is best for each pseudo register. The source
-file is @file{regclass.c}.
-
-@cindex register allocation
-@cindex local register allocation
-@item
-Local register allocation (@file{local-alloc.c}). This pass allocates
-hard registers to pseudo registers that are used only within one basic
-block. Because the basic block is linear, it can use fast and
-powerful techniques to do a very good job.
-
-@opindex dl
-The option @option{-dl} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.lreg} to
-the input file name.
-
-@cindex global register allocation
-@item
-Global register allocation (@file{global.c}). This pass
-allocates hard registers for the remaining pseudo registers (those
-whose life spans are not contained in one basic block).
-
-@cindex reloading
-@item
-Reloading. This pass renumbers pseudo registers with the hardware
-registers numbers they were allocated. Pseudo registers that did not
-get hard registers are replaced with stack slots. Then it finds
-instructions that are invalid because a value has failed to end up in
-a register, or has ended up in a register of the wrong kind. It fixes
-up these instructions by reloading the problematical values
-temporarily into registers. Additional instructions are generated to
-do the copying.
-
-The reload pass also optionally eliminates the frame pointer and inserts
-instructions to save and restore call-clobbered registers around calls.
-
-Source files are @file{reload.c} and @file{reload1.c}, plus the header
-@file{reload.h} used for communication between them.
-
-@opindex dg
-The option @option{-dg} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.greg} to
-the input file name.
-
-@cindex instruction scheduling
-@cindex scheduling, instruction
-@item
-Instruction scheduling is repeated here to try to avoid pipeline stalls
-due to memory loads generated for spilled pseudo registers.
-
-@opindex dR
-The option @option{-dR} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.sched2}
-to the input file name.
-
-@cindex basic block reordering
-@cindex reordering, block
-@item
-Basic block reordering. This pass implements profile guided code
-positioning. If profile information is not available, various types of
-static analysis are performed to make the predictions normally coming
-from the profile feedback (IE execution frequency, branch probability,
-etc). It is implemented in the file @file{bb-reorder.c}, and the
-various prediction routines are in @file{predict.c}.
-
-@opindex dB
-The option @option{-dB} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.bbro} to
-the input file name.
-
-@cindex cross-jumping
-@cindex no-op move instructions
-@item
-Jump optimization is repeated, this time including cross-jumping
-and deletion of no-op move instructions.
-
-@opindex dJ
-The option @option{-dJ} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.jump2}
-to the input file name.
-
-@cindex delayed branch scheduling
-@cindex scheduling, delayed branch
-@item
-Delayed branch scheduling. This optional pass attempts to find
-instructions that can go into the delay slots of other instructions,
-usually jumps and calls. The source file name is @file{reorg.c}.
-
-@opindex dd
-The option @option{-dd} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.dbr}
-to the input file name.
-
-@cindex branch shortening
-@item
-Branch shortening. On many RISC machines, branch instructions have a
-limited range. Thus, longer sequences of instructions must be used for
-long branches. In this pass, the compiler figures out what how far each
-instruction will be from each other instruction, and therefore whether
-the usual instructions, or the longer sequences, must be used for each
-branch.
-
-@cindex register-to-stack conversion
-@item
-Conversion from usage of some hard registers to usage of a register
-stack may be done at this point. Currently, this is supported only
-for the floating-point registers of the Intel 80387 coprocessor. The
-source file name is @file{reg-stack.c}.
-
-@opindex dk
-The options @option{-dk} causes a debugging dump of the RTL code after
-this pass. This dump file's name is made by appending @samp{.stack}
-to the input file name.
-
-@cindex final pass
-@cindex peephole optimization
-@item
-Final. This pass outputs the assembler code for the function. It is
-also responsible for identifying spurious test and compare
-instructions. Machine-specific peephole optimizations are performed
-at the same time. The function entry and exit sequences are generated
-directly as assembler code in this pass; they never exist as RTL@.
-
-The source files are @file{final.c} plus @file{insn-output.c}; the
-latter is generated automatically from the machine description by the
-tool @file{genoutput}. The header file @file{conditions.h} is used
-for communication between these files.
-
-@cindex debugging information generation
-@item
-Debugging information output. This is run after final because it must
-output the stack slot offsets for pseudo registers that did not get
-hard registers. Source files are @file{dbxout.c} for DBX symbol table
-format, @file{sdbout.c} for SDB symbol table format, @file{dwarfout.c}
-for DWARF symbol table format, and the files @file{dwarf2out.c} and
-@file{dwarf2asm.c} for DWARF2 symbol table format.
-@end itemize
-
-Some additional files are used by all or many passes:
-
-@itemize @bullet
-@item
-Every pass uses @file{machmode.def} and @file{machmode.h} which define
-the machine modes.
-
-@item
-Several passes use @file{real.h}, which defines the default
-representation of floating point constants and how to operate on them.
-
-@item
-All the passes that work with RTL use the header files @file{rtl.h}
-and @file{rtl.def}, and subroutines in file @file{rtl.c}. The tools
-@code{gen*} also use these files to read and work with the machine
-description RTL@.
-
-@item
-All the tools that read the machine description use support routines
-found in @file{gensupport.c}, @file{errors.c}, and @file{read-rtl.c}.
-
-@findex genconfig
-@item
-Several passes refer to the header file @file{insn-config.h} which
-contains a few parameters (C macro definitions) generated
-automatically from the machine description RTL by the tool
-@code{genconfig}.
-
-@cindex instruction recognizer
-@item
-Several passes use the instruction recognizer, which consists of
-@file{recog.c} and @file{recog.h}, plus the files @file{insn-recog.c}
-and @file{insn-extract.c} that are generated automatically from the
-machine description by the tools @file{genrecog} and
-@file{genextract}.
-
-@item
-Several passes use the header files @file{regs.h} which defines the
-information recorded about pseudo register usage, and @file{basic-block.h}
-which defines the information recorded about basic blocks.
-
-@item
-@file{hard-reg-set.h} defines the type @code{HARD_REG_SET}, a bit-vector
-with a bit for each hard register, and some macros to manipulate it.
-This type is just @code{int} if the machine has few enough hard registers;
-otherwise it is an array of @code{int} and some of the macros expand
-into loops.
-
-@item
-Several passes use instruction attributes. A definition of the
-attributes defined for a particular machine is in file
-@file{insn-attr.h}, which is generated from the machine description by
-the program @file{genattr}. The file @file{insn-attrtab.c} contains
-subroutines to obtain the attribute values for insns. It is generated
-from the machine description by the program @file{genattrtab}.
-@end itemize
-@end ifset
-
-@ifset INTERNALS
-@include c-tree.texi
-@include rtl.texi
-@include md.texi
-@include tm.texi
-@end ifset
-
-@ifset INTERNALS
-@node Config
-@chapter The Configuration File
-@cindex configuration file
-@cindex @file{xm-@var{machine}.h}
-
-The configuration file @file{xm-@var{machine}.h} contains macro
-definitions that describe the machine and system on which the compiler
-is running, unlike the definitions in @file{@var{machine}.h}, which
-describe the machine for which the compiler is producing output. Most
-of the values in @file{xm-@var{machine}.h} are actually the same on all
-machines that GCC runs on, so large parts of all configuration files
-are identical. But there are some macros that vary:
-
-@table @code
-@findex USG
-@item USG
-Define this macro if the host system is System V@.
-
-@findex VMS
-@item VMS
-Define this macro if the host system is VMS@.
-
-@findex FATAL_EXIT_CODE
-@item FATAL_EXIT_CODE
-A C expression for the status code to be returned when the compiler
-exits after serious errors. The default is the system-provided macro
-@samp{EXIT_FAILURE}, or @samp{1} if the system doesn't define that
-macro. Define this macro only if these defaults are incorrect.
-
-@findex SUCCESS_EXIT_CODE
-@item SUCCESS_EXIT_CODE
-A C expression for the status code to be returned when the compiler
-exits without serious errors. (Warnings are not serious errors.) The
-default is the system-provided macro @samp{EXIT_SUCCESS}, or @samp{0} if
-the system doesn't define that macro. Define this macro only if these
-defaults are incorrect.
-
-@findex HOST_WORDS_BIG_ENDIAN
-@item HOST_WORDS_BIG_ENDIAN
-Defined if the host machine stores words of multi-word values in
-big-endian order. (GCC does not depend on the host byte ordering
-within a word.)
-
-@findex HOST_FLOAT_WORDS_BIG_ENDIAN
-@item HOST_FLOAT_WORDS_BIG_ENDIAN
-Define this macro to be 1 if the host machine stores @code{DFmode},
-@code{XFmode} or @code{TFmode} floating point numbers in memory with the
-word containing the sign bit at the lowest address; otherwise, define it
-to be zero.
-
-This macro need not be defined if the ordering is the same as for
-multi-word integers.
-
-@findex HOST_FLOAT_FORMAT
-@item HOST_FLOAT_FORMAT
-A numeric code distinguishing the floating point format for the host
-machine. See @code{TARGET_FLOAT_FORMAT} in @ref{Storage Layout} for the
-alternatives and default.
-
-@findex HOST_BITS_PER_CHAR
-@item HOST_BITS_PER_CHAR
-A C expression for the number of bits in @code{char} on the host
-machine.
-
-@findex HOST_BITS_PER_SHORT
-@item HOST_BITS_PER_SHORT
-A C expression for the number of bits in @code{short} on the host
-machine.
-
-@findex HOST_BITS_PER_INT
-@item HOST_BITS_PER_INT
-A C expression for the number of bits in @code{int} on the host
-machine.
-
-@findex HOST_BITS_PER_LONG
-@item HOST_BITS_PER_LONG
-A C expression for the number of bits in @code{long} on the host
-machine.
-
-@findex HOST_BITS_PER_LONGLONG
-@item HOST_BITS_PER_LONGLONG
-A C expression for the number of bits in @code{long long} on the host
-machine.
-
-@findex ONLY_INT_FIELDS
-@item ONLY_INT_FIELDS
-Define this macro to indicate that the host compiler only supports
-@code{int} bit-fields, rather than other integral types, including
-@code{enum}, as do most C compilers.
-
-@findex OBSTACK_CHUNK_SIZE
-@item OBSTACK_CHUNK_SIZE
-A C expression for the size of ordinary obstack chunks.
-If you don't define this, a usually-reasonable default is used.
-
-@findex OBSTACK_CHUNK_ALLOC
-@item OBSTACK_CHUNK_ALLOC
-The function used to allocate obstack chunks.
-If you don't define this, @code{xmalloc} is used.
-
-@findex OBSTACK_CHUNK_FREE
-@item OBSTACK_CHUNK_FREE
-The function used to free obstack chunks.
-If you don't define this, @code{free} is used.
-
-@findex USE_C_ALLOCA
-@item USE_C_ALLOCA
-Define this macro to indicate that the compiler is running with the
-@code{alloca} implemented in C@. This version of @code{alloca} can be
-found in the file @file{alloca.c}; to use it, you must also alter the
-@file{Makefile} variable @code{ALLOCA}. (This is done automatically
-for the systems on which we know it is needed.)
-
-If you do define this macro, you should probably do it as follows:
-
-@example
-#ifndef __GNUC__
-#define USE_C_ALLOCA
-#else
-#define alloca __builtin_alloca
-#endif
-@end example
-
-@noindent
-so that when the compiler is compiled with GCC it uses the more
-efficient built-in @code{alloca} function.
-
-@item FUNCTION_CONVERSION_BUG
-@findex FUNCTION_CONVERSION_BUG
-Define this macro to indicate that the host compiler does not properly
-handle converting a function value to a pointer-to-function when it is
-used in an expression.
-
-@findex MULTIBYTE_CHARS
-@item MULTIBYTE_CHARS
-Define this macro to enable support for multibyte characters in the
-input to GCC@. This requires that the host system support the ISO C
-library functions for converting multibyte characters to wide
-characters.
-
-@findex POSIX
-@item POSIX
-Define this if your system is POSIX.1 compliant.
-
-@findex PATH_SEPARATOR
-@item PATH_SEPARATOR
-Define this macro to be a C character constant representing the
-character used to separate components in paths. The default value is
-the colon character
-
-@findex DIR_SEPARATOR
-@item DIR_SEPARATOR
-If your system uses some character other than slash to separate
-directory names within a file specification, define this macro to be a C
-character constant specifying that character. When GCC displays file
-names, the character you specify will be used. GCC will test for
-both slash and the character you specify when parsing filenames.
-
-@findex DIR_SEPARATOR_2
-@item DIR_SEPARATOR_2
-If your system uses an alternative character other than
-@samp{DIR_SEPARATOR} to separate directory names within a file
-specification, define this macro to be a C character constant specifying
-that character. If you define this macro, GCC will test for slash,
-@samp{DIR_SEPARATOR}, and @samp{DIR_SEPARATOR_2} when parsing filenames.
-
-@findex TARGET_OBJECT_SUFFIX
-@item TARGET_OBJECT_SUFFIX
-Define this macro to be a C string representing the suffix for object
-files on your target machine. If you do not define this macro, GCC will
-use @samp{.o} as the suffix for object files.
-
-@findex TARGET_EXECUTABLE_SUFFIX
-@item TARGET_EXECUTABLE_SUFFIX
-Define this macro to be a C string representing the suffix to be
-automatically added to executable files on your target machine. If you
-do not define this macro, GCC will use the null string as the suffix for
-executable files.
-
-@findex HOST_OBJECT_SUFFIX
-@item HOST_OBJECT_SUFFIX
-Define this macro to be a C string representing the suffix for object
-files on your host machine (@samp{xm-*.h}). If you do not define this
-macro, GCC will use @samp{.o} as the suffix for object files.
-
-@findex HOST_EXECUTABLE_SUFFIX
-@item HOST_EXECUTABLE_SUFFIX
-Define this macro to be a C string representing the suffix for
-executable files on your host machine (@samp{xm-*.h}). If you do not
-define this macro, GCC will use the null string as the suffix for
-executable files.
-
-@findex HOST_BIT_BUCKET
-@item HOST_BIT_BUCKET
-The name of a file or file-like object on the host system which acts as
-a ``bit bucket''. If you do not define this macro, GCC will use
-@samp{/dev/null} as the bit bucket. If the target does not support a
-bit bucket, this should be defined to the null string, or some other
-illegal filename. If the bit bucket is not writable, GCC will use a
-temporary file instead.
-
-@findex COLLECT_EXPORT_LIST
-@item COLLECT_EXPORT_LIST
-If defined, @code{collect2} will scan the individual object files
-specified on its command line and create an export list for the linker.
-Define this macro for systems like AIX, where the linker discards
-object files that are not referenced from @code{main} and uses export
-lists.
-
-@findex COLLECT2_HOST_INITIALIZATION
-@item COLLECT2_HOST_INITIALIZATION
-If defined, a C statement (sans semicolon) that performs host-dependent
-initialization when @code{collect2} is being initialized.
-
-@findex GCC_DRIVER_HOST_INITIALIZATION
-@item GCC_DRIVER_HOST_INITIALIZATION
-If defined, a C statement (sans semicolon) that performs host-dependent
-initialization when a compilation driver is being initialized.
-
-@findex UPDATE_PATH_HOST_CANONICALIZE
-@item UPDATE_PATH_HOST_CANONICALIZE (@var{path}, @var{key})
-If defined, a C statement (sans semicolon) that performs host-dependent
-canonicalization when a path used in a compilation driver or preprocessor is
-canonicalized. @var{path} is the path to be canonicalized, and @var{key} is
-a translation prefix when its value isn't @code{NULL}. If the C statement
-does canonicalize @var{path}, the new path should be returned.
-@end table
-
-@findex bzero
-@findex bcmp
-In addition, configuration files for system V define @code{bcopy},
-@code{bzero} and @code{bcmp} as aliases. Some files define @code{alloca}
-as a macro when compiled with GCC, in order to take advantage of the
-benefit of GCC's built-in @code{alloca}.
-
-@node Fragments
-@chapter Makefile Fragments
-@cindex makefile fragment
-
-When you configure GCC using the @file{configure} script
-(@pxref{Installation}), it will construct the file @file{Makefile} from
-the template file @file{Makefile.in}. When it does this, it will
-incorporate makefile fragment files from the @file{config} directory,
-named @file{t-@var{target}} and @file{x-@var{host}}. If these files do
-not exist, it means nothing needs to be added for a given target or
-host.
-
-@menu
-* Target Fragment:: Writing the @file{t-@var{target}} file.
-* Host Fragment:: Writing the @file{x-@var{host}} file.
-@end menu
-
-@node Target Fragment
-@section The Target Makefile Fragment
-@cindex target makefile fragment
-@cindex @file{t-@var{target}}
-
-The target makefile fragment, @file{t-@var{target}}, defines special
-target dependent variables and targets used in the @file{Makefile}:
-
-@table @code
-@findex LIBGCC2_CFLAGS
-@item LIBGCC2_CFLAGS
-Compiler flags to use when compiling @file{libgcc2.c}.
-
-@findex LIB2FUNCS_EXTRA
-@item LIB2FUNCS_EXTRA
-A list of source file names to be compiled or assembled and inserted
-into @file{libgcc.a}.
-
-@findex Floating Point Emulation
-@item Floating Point Emulation
-To have GCC include software floating point libraries in @file{libgcc.a}
-define @code{FPBIT} and @code{DPBIT} along with a few rules as follows:
-@smallexample
-# We want fine grained libraries, so use the new code
-# to build the floating point emulation libraries.
-FPBIT = fp-bit.c
-DPBIT = dp-bit.c
-
-
-fp-bit.c: $(srcdir)/config/fp-bit.c
- echo '#define FLOAT' > fp-bit.c
- cat $(srcdir)/config/fp-bit.c >> fp-bit.c
-
-dp-bit.c: $(srcdir)/config/fp-bit.c
- cat $(srcdir)/config/fp-bit.c > dp-bit.c
-@end smallexample
-
-You may need to provide additional #defines at the beginning of @file{fp-bit.c}
-and @file{dp-bit.c} to control target endianness and other options.
-
-
-@findex CRTSTUFF_T_CFLAGS
-@item CRTSTUFF_T_CFLAGS
-Special flags used when compiling @file{crtstuff.c}.
-@xref{Initialization}.
-
-@findex CRTSTUFF_T_CFLAGS_S
-@item CRTSTUFF_T_CFLAGS_S
-Special flags used when compiling @file{crtstuff.c} for shared
-linking. Used if you use @file{crtbeginS.o} and @file{crtendS.o}
-in @code{EXTRA-PARTS}.
-@xref{Initialization}.
-
-@findex MULTILIB_OPTIONS
-@item MULTILIB_OPTIONS
-For some targets, invoking GCC in different ways produces objects
-that can not be linked together. For example, for some targets GCC
-produces both big and little endian code. For these targets, you must
-arrange for multiple versions of @file{libgcc.a} to be compiled, one for
-each set of incompatible options. When GCC invokes the linker, it
-arranges to link in the right version of @file{libgcc.a}, based on
-the command line options used.
-
-The @code{MULTILIB_OPTIONS} macro lists the set of options for which
-special versions of @file{libgcc.a} must be built. Write options that
-are mutually incompatible side by side, separated by a slash. Write
-options that may be used together separated by a space. The build
-procedure will build all combinations of compatible options.
-
-For example, if you set @code{MULTILIB_OPTIONS} to @samp{m68000/m68020
-msoft-float}, @file{Makefile} will build special versions of
-@file{libgcc.a} using the following sets of options: @option{-m68000},
-@option{-m68020}, @option{-msoft-float}, @samp{-m68000 -msoft-float}, and
-@samp{-m68020 -msoft-float}.
-
-@findex MULTILIB_DIRNAMES
-@item MULTILIB_DIRNAMES
-If @code{MULTILIB_OPTIONS} is used, this variable specifies the
-directory names that should be used to hold the various libraries.
-Write one element in @code{MULTILIB_DIRNAMES} for each element in
-@code{MULTILIB_OPTIONS}. If @code{MULTILIB_DIRNAMES} is not used, the
-default value will be @code{MULTILIB_OPTIONS}, with all slashes treated
-as spaces.
-
-For example, if @code{MULTILIB_OPTIONS} is set to @samp{m68000/m68020
-msoft-float}, then the default value of @code{MULTILIB_DIRNAMES} is
-@samp{m68000 m68020 msoft-float}. You may specify a different value if
-you desire a different set of directory names.
-
-@findex MULTILIB_MATCHES
-@item MULTILIB_MATCHES
-Sometimes the same option may be written in two different ways. If an
-option is listed in @code{MULTILIB_OPTIONS}, GCC needs to know about
-any synonyms. In that case, set @code{MULTILIB_MATCHES} to a list of
-items of the form @samp{option=option} to describe all relevant
-synonyms. For example, @samp{m68000=mc68000 m68020=mc68020}.
-
-@findex MULTILIB_EXCEPTIONS
-@item MULTILIB_EXCEPTIONS
-Sometimes when there are multiple sets of @code{MULTILIB_OPTIONS} being
-specified, there are combinations that should not be built. In that
-case, set @code{MULTILIB_EXCEPTIONS} to be all of the switch exceptions
-in shell case syntax that should not be built.
-
-For example, in the PowerPC embedded ABI support, it is not desirable
-to build libraries compiled with the @option{-mcall-aix} option
-and either of the @option{-fleading-underscore} or @option{-mlittle} options
-at the same time. Therefore @code{MULTILIB_EXCEPTIONS} is set to
-@code{*mcall-aix/*fleading-underscore* *mlittle/*mcall-aix*}.
-
-@findex MULTILIB_EXTRA_OPTS
-@item MULTILIB_EXTRA_OPTS
-Sometimes it is desirable that when building multiple versions of
-@file{libgcc.a} certain options should always be passed on to the
-compiler. In that case, set @code{MULTILIB_EXTRA_OPTS} to be the list
-of options to be used for all builds.
-@end table
-
-@node Host Fragment
-@section The Host Makefile Fragment
-@cindex host makefile fragment
-@cindex @file{x-@var{host}}
-
-The host makefile fragment, @file{x-@var{host}}, defines special host
-dependent variables and targets used in the @file{Makefile}:
-
-@table @code
-@findex CC
-@item CC
-The compiler to use when building the first stage.
-
-@findex INSTALL
-@item INSTALL
-The install program to use.
-@end table
-@end ifset
+@include trouble.texi
+@include bugreport.texi
+@include service.texi
+@include contribute.texi
@include funding.texi
-
-@node GNU/Linux
-@unnumbered Linux and the GNU Project
-
-Many computer users run a modified version of the GNU system every
-day, without realizing it. Through a peculiar turn of events, the
-version of GNU which is widely used today is more often known as
-``Linux'', and many users are not aware of the extent of its
-connection with the GNU Project.
-
-There really is a Linux; it is a kernel, and these people are using
-it. But you can't use a kernel by itself; a kernel is useful only as
-part of a whole system. The system in which Linux is typically used
-is a modified variant of the GNU system---in other words, a Linux-based
-GNU system.
-
-Many users are not fully aware of the distinction between the kernel,
-which is Linux, and the whole system, which they also call ``Linux''.
-The ambiguous use of the name doesn't promote understanding.
-
-Programmers generally know that Linux is a kernel. But since they
-have generally heard the whole system called ``Linux'' as well, they
-often envisage a history which fits that name. For example, many
-believe that once Linus Torvalds finished writing the kernel, his
-friends looked around for other free software, and for no particular
-reason most everything necessary to make a Unix-like system was
-already available.
-
-What they found was no accident---it was the GNU system. The available
-free software added up to a complete system because the GNU Project
-had been working since 1984 to make one. The GNU Manifesto
-had set forth the goal of developing a free Unix-like system, called
-GNU@. By the time Linux was written, the system was almost finished.
-
-Most free software projects have the goal of developing a particular
-program for a particular job. For example, Linus Torvalds set out to
-write a Unix-like kernel (Linux); Donald Knuth set out to write a text
-formatter (TeX); Bob Scheifler set out to develop a window system (X
-Windows). It's natural to measure the contribution of this kind of
-project by specific programs that came from the project.
-
-If we tried to measure the GNU Project's contribution in this way,
-what would we conclude? One CD-ROM vendor found that in their ``Linux
-distribution'', GNU software was the largest single contingent, around
-28% of the total source code, and this included some of the essential
-major components without which there could be no system. Linux itself
-was about 3%. So if you were going to pick a name for the system
-based on who wrote the programs in the system, the most appropriate
-single choice would be ``GNU''@.
-
-But we don't think that is the right way to consider the question.
-The GNU Project was not, is not, a project to develop specific
-software packages. It was not a project to develop a C compiler,
-although we did. It was not a project to develop a text editor,
-although we developed one. The GNU Project's aim was to develop
-@emph{a complete free Unix-like system}.
-
-Many people have made major contributions to the free software in the
-system, and they all deserve credit. But the reason it is @emph{a
-system}---and not just a collection of useful programs---is because the
-GNU Project set out to make it one. We wrote the programs that were
-needed to make a @emph{complete} free system. We wrote essential but
-unexciting major components, such as the assembler and linker, because
-you can't have a system without them. A complete system needs more
-than just programming tools, so we wrote other components as well,
-such as the Bourne Again SHell, the PostScript interpreter
-Ghostscript, and the GNU C library.
-
-By the early 90s we had put together the whole system aside from the
-kernel (and we were also working on a kernel, the GNU Hurd, which runs
-on top of Mach). Developing this kernel has been a lot harder than we
-expected, and we are still working on finishing it.
-
-Fortunately, you don't have to wait for it, because Linux is working
-now. When Linus Torvalds wrote Linux, he filled the last major gap.
-People could then put Linux together with the GNU system to make a
-complete free system: a Linux-based GNU system (or GNU/Linux system,
-for short).
-
-Putting them together sounds simple, but it was not a trivial job.
-The GNU C library (called glibc for short) needed substantial changes.
-Integrating a complete system as a distribution that would work ``out
-of the box'' was a big job, too. It required addressing the issue of
-how to install and boot the system---a problem we had not tackled,
-because we hadn't yet reached that point. The people who developed
-the various system distributions made a substantial contribution.
-
-The GNU Project supports GNU/Linux systems as well as @emph{the}
-GNU system---even with funds. We funded the rewriting of the
-Linux-related extensions to the GNU C library, so that now they are
-well integrated, and the newest GNU/Linux systems use the current
-library release with no changes. We also funded an early stage of the
-development of Debian GNU/Linux.
-
-We use Linux-based GNU systems today for most of our work, and we hope
-you use them too. But please don't confuse the public by using the
-name ``Linux'' ambiguously. Linux is the kernel, one of the essential
-major components of the system. The system as a whole is more or less
-the GNU system.
-
-@node Copying
-@unnumbered GNU GENERAL PUBLIC LICENSE
-@center Version 2, June 1991
-
-@display
-Copyright @copyright{} 1989, 1991 Free Software Foundation, Inc.
-59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
-
-Everyone is permitted to copy and distribute verbatim copies
-of this license document, but changing it is not allowed.
-@end display
-
-@unnumberedsec 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.
-
-@iftex
-@unnumberedsec TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
-@end iftex
-@ifnottex
-@center TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
-@end ifnottex
-
-@enumerate 0
-@item
-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.
-
-@item
-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.
-
-@item
-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:
-
-@enumerate a
-@item
-You must cause the modified files to carry prominent notices
-stating that you changed the files and the date of any change.
-
-@item
-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.
-
-@item
-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.)
-@end enumerate
-
-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.
-
-@item
-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:
-
-@enumerate a
-@item
-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,
-
-@item
-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,
-
-@item
-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.)
-@end enumerate
-
-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.
-
-@item
-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.
-
-@item
-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.
-
-@item
-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.
-
-@item
-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.
-
-@item
-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.
-
-@item
-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.
-
-@item
-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.
-
-@iftex
-@heading NO WARRANTY
-@end iftex
-@ifnottex
-@center NO WARRANTY
-@end ifnottex
-
-@item
-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.
-
-@item
-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 enumerate
-
-@iftex
-@heading END OF TERMS AND CONDITIONS
-@end iftex
-@ifnottex
-@center END OF TERMS AND CONDITIONS
-@end ifnottex
-
-@page
-@unnumberedsec 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.
-
-@smallexample
-@var{one line to give the program's name and a brief idea of what it does.}
-Copyright (C) @var{yyyy} @var{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., 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA.
-@end smallexample
-
-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:
-
-@smallexample
-Gnomovision version 69, Copyright (C) @var{yyyy} @var{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.
-@end smallexample
-
-The hypothetical commands @samp{show w} and @samp{show c} should show
-the appropriate parts of the General Public License. Of course, the
-commands you use may be called something other than @samp{show w} and
-@samp{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:
-
-@smallexample
-Yoyodyne, Inc., hereby disclaims all copyright interest in the program
-`Gnomovision' (which makes passes at compilers) written by James Hacker.
-
-@var{signature of Ty Coon}, 1 April 1989
-Ty Coon, President of Vice
-@end smallexample
-
-@include gpl.texi
+@include gnu.texi
+@include gpl_v3.texi
@c ---------------------------------------------------------------------
@c GFDL
@include fdl.texi
-@node Contributors
-@unnumbered Contributors to GCC
-@cindex contributors
@include contrib.texi
@c ---------------------------------------------------------------------
@printindex op
-@node Index
-@unnumbered Index
+@node Keyword Index
+@unnumbered Keyword Index
@printindex cp
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