+2001-11-04 Toon Moene <toon@moene.indiv.nluug.nl>
+
+ * g77.texi: Split off invoke.texi (preliminary to using it
+ to generate a man page).
+ * Make-lang.in: Reflect in build rules.
+
Fri Nov 2 10:51:34 2001 Kaveh R. Ghazi <ghazi@caip.rutgers.edu>
* com.c (ffecom_initialize_char_syntax_, U_CHAR, is_idchar,
# g77 documentation.
$(srcdir)/f/g77.info: $(srcdir)/f/g77.texi $(srcdir)/f/bugs.texi \
- $(srcdir)/f/ffe.texi \
+ $(srcdir)/f/ffe.texi $(srcdir)/f/invoke.texi \
$(srcdir)/f/news.texi $(srcdir)/f/intdoc.texi \
$(srcdir)/f/root.texi $(srcdir)/doc/include/fdl.texi \
$(srcdir)/doc/include/gpl.texi \
else true; fi
f/g77.dvi: $(srcdir)/f/g77.texi $(srcdir)/f/bugs.texi \
- $(srcdir)/f/ffe.texi \
+ $(srcdir)/f/ffe.texi $(srcdir)/f/invoke.texi \
$(srcdir)/f/news.texi $(srcdir)/f/intdoc.texi \
$(srcdir)/f/root.texi $(srcdir)/doc/include/fdl.texi \
$(srcdir)/doc/include/gpl.texi \
* Environment Variables:: Env vars that affect GNU Fortran.
@end menu
-@node Option Summary
-@section Option Summary
-
-Here is a summary of all the options specific to GNU Fortran, grouped
-by type. Explanations are in the following sections.
-
-@table @emph
-@item Overall Options
-@xref{Overall Options,,Options Controlling the Kind of Output}.
-@smallexample
--fversion -fset-g77-defaults -fno-silent
-@end smallexample
-
-@item Shorthand Options
-@xref{Shorthand Options}.
-@smallexample
--ff66 -fno-f66 -ff77 -fno-f77 -fno-ugly
-@end smallexample
-
-@item Fortran Language Options
-@xref{Fortran Dialect Options,,Options Controlling Fortran Dialect}.
-@smallexample
--ffree-form -fno-fixed-form -ff90
--fvxt -fdollar-ok -fno-backslash
--fno-ugly-args -fno-ugly-assign -fno-ugly-assumed
--fugly-comma -fugly-complex -fugly-init -fugly-logint
--fonetrip -ftypeless-boz
--fintrin-case-initcap -fintrin-case-upper
--fintrin-case-lower -fintrin-case-any
--fmatch-case-initcap -fmatch-case-upper
--fmatch-case-lower -fmatch-case-any
--fsource-case-upper -fsource-case-lower
--fsource-case-preserve
--fsymbol-case-initcap -fsymbol-case-upper
--fsymbol-case-lower -fsymbol-case-any
--fcase-strict-upper -fcase-strict-lower
--fcase-initcap -fcase-upper -fcase-lower -fcase-preserve
--ff2c-intrinsics-delete -ff2c-intrinsics-hide
--ff2c-intrinsics-disable -ff2c-intrinsics-enable
--fbadu77-intrinsics-delete -fbadu77-intrinsics-hide
--fbadu77-intrinsics-disable -fbadu77-intrinsics-enable
--ff90-intrinsics-delete -ff90-intrinsics-hide
--ff90-intrinsics-disable -ff90-intrinsics-enable
--fgnu-intrinsics-delete -fgnu-intrinsics-hide
--fgnu-intrinsics-disable -fgnu-intrinsics-enable
--fmil-intrinsics-delete -fmil-intrinsics-hide
--fmil-intrinsics-disable -fmil-intrinsics-enable
--funix-intrinsics-delete -funix-intrinsics-hide
--funix-intrinsics-disable -funix-intrinsics-enable
--fvxt-intrinsics-delete -fvxt-intrinsics-hide
--fvxt-intrinsics-disable -fvxt-intrinsics-enable
--ffixed-line-length-@var{n} -ffixed-line-length-none
-@end smallexample
-
-@item Warning Options
-@xref{Warning Options,,Options to Request or Suppress Warnings}.
-@smallexample
--fsyntax-only -pedantic -pedantic-errors -fpedantic
--w -Wno-globals -Wimplicit -Wunused -Wuninitialized
--Wall -Wsurprising
--Werror -W
-@end smallexample
-
-@item Debugging Options
-@xref{Debugging Options,,Options for Debugging Your Program or GCC}.
-@smallexample
--g
-@end smallexample
-
-@item Optimization Options
-@xref{Optimize Options,,Options that Control Optimization}.
-@smallexample
--malign-double
--ffloat-store -fforce-mem -fforce-addr -fno-inline
--ffast-math -fstrength-reduce -frerun-cse-after-loop
--funsafe-math-optimizations -fno-trapping-math
--fexpensive-optimizations -fdelayed-branch
--fschedule-insns -fschedule-insn2 -fcaller-saves
--funroll-loops -funroll-all-loops
--fno-move-all-movables -fno-reduce-all-givs
--fno-rerun-loop-opt
-@end smallexample
-
-@item Directory Options
-@xref{Directory Options,,Options for Directory Search}.
-@smallexample
--I@var{dir} -I-
-@end smallexample
-
-@item Code Generation Options
-@xref{Code Gen Options,,Options for Code Generation Conventions}.
-@smallexample
--fno-automatic -finit-local-zero -fno-f2c
--ff2c-library -fno-underscoring -fno-ident
--fpcc-struct-return -freg-struct-return
--fshort-double -fno-common -fpack-struct
--fzeros -fno-second-underscore
--femulate-complex
--falias-check -fargument-alias
--fargument-noalias -fno-argument-noalias-global
--fno-globals -fflatten-arrays
--fbounds-check -ffortran-bounds-check
-@end smallexample
-@end table
-
-@menu
-* Overall Options:: Controlling the kind of output:
- an executable, object files, assembler files,
- or preprocessed source.
-* Shorthand Options:: Options that are shorthand for other options.
-* Fortran Dialect Options:: Controlling the variant of Fortran language
- compiled.
-* Warning Options:: How picky should the compiler be?
-* Debugging Options:: Symbol tables, measurements, and debugging dumps.
-* Optimize Options:: How much optimization?
-* Preprocessor Options:: Controlling header files and macro definitions.
- Also, getting dependency information for Make.
-* Directory Options:: Where to find header files and libraries.
- Where to find the compiler executable files.
-* Code Gen Options:: Specifying conventions for function calls, data layout
- and register usage.
-@end menu
-
-@node Overall Options
-@section Options Controlling the Kind of Output
-@cindex overall options
-@cindex options, overall
-
-Compilation can involve as many as four stages: preprocessing, code
-generation (often what is really meant by the term ``compilation''),
-assembly, and linking, always in that order. The first three
-stages apply to an individual source file, and end by producing an
-object file; linking combines all the object files (those newly
-compiled, and those specified as input) into an executable file.
-
-@cindex file name suffix
-@cindex suffixes, file name
-@cindex file name extension
-@cindex extensions, file name
-@cindex file type
-@cindex types, file
-For any given input file, the file name suffix determines what kind of
-program is contained in the file---that is, the language in which the
-program is written is generally indicated by the suffix.
-Suffixes specific to GNU Fortran are listed below.
-@xref{Overall Options,,gcc,Using and Porting GNU CC}, for
-information on suffixes recognized by GNU CC.
-
-@table @code
-@cindex .f filename suffix
-@cindex .for filename suffix
-@cindex .FOR filename suffix
-@item @var{file}.f
-@item @var{file}.for
-@item @var{file}.FOR
-Fortran source code that should not be preprocessed.
-
-Such source code cannot contain any preprocessor directives, such
-as @code{#include}, @code{#define}, @code{#if}, and so on.
-
-You can force @samp{.f} files to be preprocessed by @code{cpp} by using
-@samp{-x f77-cpp-input}.
-@xref{LEX}.
-
-@cindex preprocessor
-@cindex C preprocessor
-@cindex cpp preprocessor
-@cindex Fortran preprocessor
-@cindex cpp program
-@cindex programs, cpp
-@cindex .F filename suffix
-@cindex .fpp filename suffix
-@cindex .FPP filename suffix
-@item @var{file}.F
-@item @var{file}.fpp
-@item @var{file}.FPP
-Fortran source code that must be preprocessed (by the C preprocessor
-@code{cpp}, which is part of GNU CC).
-
-Note that preprocessing is not extended to the contents of
-files included by the @code{INCLUDE} directive---the @code{#include}
-preprocessor directive must be used instead.
-
-@cindex Ratfor preprocessor
-@cindex programs, @code{ratfor}
-@cindex @samp{.r} filename suffix
-@cindex @code{ratfor}
-@item @var{file}.r
-Ratfor source code, which must be preprocessed by the @code{ratfor}
-command, which is available separately (as it is not yet part of the GNU
-Fortran distribution).
-One version in Fortran, adapted for use with @code{g77}, is at
-@uref{ftp://members.aol.com/n8tm/rat7.uue} (of uncertain copyright
-status). Another, public domain version in C is at
-@uref{http://sepwww.stanford.edu/sep/prof/ratfor.shar.2}.
-@end table
-
-UNIX users typically use the @file{@var{file}.f} and @file{@var{file}.F}
-nomenclature.
-Users of other operating systems, especially those that cannot
-distinguish upper-case
-letters from lower-case letters in their file names, typically use
-the @file{@var{file}.for} and @file{@var{file}.fpp} nomenclature.
-
-@cindex #define
-@cindex #include
-@cindex #if
-Use of the preprocessor @code{cpp} allows use of C-like
-constructs such as @code{#define} and @code{#include}, but can
-lead to unexpected, even mistaken, results due to Fortran's source file
-format.
-It is recommended that use of the C preprocessor
-be limited to @code{#include} and, in
-conjunction with @code{#define}, only @code{#if} and related directives,
-thus avoiding in-line macro expansion entirely.
-This recommendation applies especially
-when using the traditional fixed source form.
-With free source form,
-fewer unexpected transformations are likely to happen, but use of
-constructs such as Hollerith and character constants can nevertheless
-present problems, especially when these are continued across multiple
-source lines.
-These problems result, primarily, from differences between the way
-such constants are interpreted by the C preprocessor and by a Fortran
-compiler.
-
-Another example of a problem that results from using the C preprocessor
-is that a Fortran comment line that happens to contain any
-characters ``interesting'' to the C preprocessor,
-such as a backslash at the end of the line,
-is not recognized by the preprocessor as a comment line,
-so instead of being passed through ``raw'',
-the line is edited according to the rules for the preprocessor.
-For example, the backslash at the end of the line is removed,
-along with the subsequent newline, resulting in the next
-line being effectively commented out---unfortunate if that
-line is a non-comment line of important code!
-
-@emph{Note:} The @samp{-traditional} and @samp{-undef} flags are supplied
-to @code{cpp} by default, to help avoid unpleasant surprises.
-@xref{Preprocessor Options,,Options Controlling the Preprocessor,
-gcc,Using and Porting GNU CC}.
-This means that ANSI C preprocessor features (such as the @samp{#}
-operator) aren't available, and only variables in the C reserved
-namespace (generally, names with a leading underscore) are liable to
-substitution by C predefines.
-Thus, if you want to do system-specific
-tests, use, for example, @samp{#ifdef __linux__} rather than @samp{#ifdef linux}.
-Use the @samp{-v} option to see exactly how the preprocessor is invoked.
-
-@cindex /*
-Unfortunately, the @samp{-traditional} flag will not avoid an error from
-anything that @code{cpp} sees as an unterminated C comment, such as:
-@smallexample
-C Some Fortran compilers accept /* as starting
-C an inline comment.
-@end smallexample
-@xref{Trailing Comment}.
-
-The following options that affect overall processing are recognized
-by the @code{g77} and @code{gcc} commands in a GNU Fortran installation:
-
-@table @code
-@cindex -fversion option
-@cindex options, -fversion
-@cindex printing version information
-@cindex version information, printing
-@cindex consistency checks
-@cindex internal consistency checks
-@cindex checks, of internal consistency
-@item -fversion
-Ensure that the @code{g77}-specific version of the compiler phase is reported,
-if run,
-and, starting in @code{egcs} version 1.1,
-that internal consistency checks in the @file{f771} program are run.
-
-This option is supplied automatically when @samp{-v} or @samp{--verbose}
-is specified as a command-line option for @code{g77} or @code{gcc}
-and when the resulting commands compile Fortran source files.
-
-@cindex -fset-g77-defaults option
-@cindex options, -fset-g77-defaults
-@item -fset-g77-defaults
-@emph{Version info:}
-This option was obsolete as of @code{egcs}
-version 1.1.
-The effect is instead achieved
-by the @code{lang_init_options} routine
-in @file{gcc/gcc/f/com.c}.
-
-@cindex consistency checks
-@cindex internal consistency checks
-@cindex checks, of internal consistency
-Set up whatever @code{gcc} options are to apply to Fortran
-compilations, and avoid running internal consistency checks
-that might take some time.
-
-This option is supplied automatically when compiling Fortran code
-via the @code{g77} or @code{gcc} command.
-The description of this option is provided so that users seeing
-it in the output of, say, @samp{g77 -v} understand why it is
-there.
-
-@cindex modifying g77
-@cindex code, modifying
-Also, developers who run @code{f771} directly might want to specify it
-by hand to get the same defaults as they would running @code{f771}
-via @code{g77} or @code{gcc}.
-However, such developers should, after linking a new @code{f771}
-executable, invoke it without this option once,
-e.g. via @kbd{./f771 -quiet < /dev/null},
-to ensure that they have not introduced any
-internal inconsistencies (such as in the table of
-intrinsics) before proceeding---@code{g77} will crash
-with a diagnostic if it detects an inconsistency.
-
-@cindex -fno-silent option
-@cindex options, -fno-silent
-@cindex f2c compatibility
-@cindex compatibility, f2c
-@cindex status, compilation
-@cindex compilation, status
-@cindex reporting compilation status
-@cindex printing compilation status
-@item -fno-silent
-Print (to @code{stderr}) the names of the program units as
-they are compiled, in a form similar to that used by popular
-UNIX @code{f77} implementations and @code{f2c}.
-@end table
-
-@xref{Overall Options,,Options Controlling the Kind of Output,
-gcc,Using and Porting GNU CC}, for information
-on more options that control the overall operation of the @code{gcc} command
-(and, by extension, the @code{g77} command).
-
-@node Shorthand Options
-@section Shorthand Options
-@cindex shorthand options
-@cindex options, shorthand
-@cindex macro options
-@cindex options, macro
-
-The following options serve as ``shorthand''
-for other options accepted by the compiler:
-
-@table @code
-@cindex -fugly option
-@cindex options, -fugly
-@item -fugly
-@cindex ugly features
-@cindex features, ugly
-@emph{Note:} This option is no longer supported.
-The information, below, is provided to aid
-in the conversion of old scripts.
-
-Specify that certain ``ugly'' constructs are to be quietly accepted.
-Same as:
-
-@smallexample
--fugly-args -fugly-assign -fugly-assumed
--fugly-comma -fugly-complex -fugly-init
--fugly-logint
-@end smallexample
-
-These constructs are considered inappropriate to use in new
-or well-maintained portable Fortran code, but widely used
-in old code.
-@xref{Distensions}, for more information.
-
-@cindex -fno-ugly option
-@cindex options, -fno-ugly
-@item -fno-ugly
-@cindex ugly features
-@cindex features, ugly
-Specify that all ``ugly'' constructs are to be noisily rejected.
-Same as:
-
-@smallexample
--fno-ugly-args -fno-ugly-assign -fno-ugly-assumed
--fno-ugly-comma -fno-ugly-complex -fno-ugly-init
--fno-ugly-logint
-@end smallexample
-
-@xref{Distensions}, for more information.
-
-@cindex -ff66 option
-@cindex options, -ff66
-@item -ff66
-@cindex FORTRAN 66
-@cindex compatibility, FORTRAN 66
-Specify that the program is written in idiomatic FORTRAN 66.
-Same as @samp{-fonetrip -fugly-assumed}.
-
-The @samp{-fno-f66} option is the inverse of @samp{-ff66}.
-As such, it is the same as @samp{-fno-onetrip -fno-ugly-assumed}.
-
-The meaning of this option is likely to be refined as future
-versions of @code{g77} provide more compatibility with other
-existing and obsolete Fortran implementations.
-
-@cindex -ff77 option
-@cindex options, -ff77
-@item -ff77
-@cindex UNIX f77
-@cindex f2c compatibility
-@cindex compatibility, f2c
-@cindex f77 compatibility
-@cindex compatibility, f77
-Specify that the program is written in idiomatic UNIX FORTRAN 77
-and/or the dialect accepted by the @code{f2c} product.
-Same as @samp{-fbackslash -fno-typeless-boz}.
-
-The meaning of this option is likely to be refined as future
-versions of @code{g77} provide more compatibility with other
-existing and obsolete Fortran implementations.
-
-@cindex -fno-f77 option
-@cindex options, -fno-f77
-@item -fno-f77
-@cindex UNIX f77
-The @samp{-fno-f77} option is @emph{not} the inverse
-of @samp{-ff77}.
-It specifies that the program is not written in idiomatic UNIX
-FORTRAN 77 or @code{f2c}, but in a more widely portable dialect.
-@samp{-fno-f77} is the same as @samp{-fno-backslash}.
-
-The meaning of this option is likely to be refined as future
-versions of @code{g77} provide more compatibility with other
-existing and obsolete Fortran implementations.
-@end table
-
-@node Fortran Dialect Options
-@section Options Controlling Fortran Dialect
-@cindex dialect options
-@cindex language, dialect options
-@cindex options, dialect
-
-The following options control the dialect of Fortran
-that the compiler accepts:
-
-@table @code
-@cindex -ffree-form option
-@cindex options, -ffree-form
-@cindex -fno-fixed-form option
-@cindex options, -fno-fixed-form
-@cindex source file format
-@cindex free form
-@cindex fixed form
-@cindex Fortran 90, features
-@item -ffree-form
-@item -fno-fixed-form
-Specify that the source file is written in free form
-(introduced in Fortran 90) instead of the more-traditional fixed form.
-
-@cindex -ff90 option
-@cindex options, -ff90
-@cindex Fortran 90, features
-@item -ff90
-Allow certain Fortran-90 constructs.
-
-This option controls whether certain
-Fortran 90 constructs are recognized.
-(Other Fortran 90 constructs
-might or might not be recognized depending on other options such as
-@samp{-fvxt}, @samp{-ff90-intrinsics-enable}, and the
-current level of support for Fortran 90.)
-
-@xref{Fortran 90}, for more information.
-
-@cindex -fvxt option
-@cindex options, -fvxt
-@item -fvxt
-@cindex Fortran 90, features
-@cindex VXT extensions
-Specify the treatment of certain constructs that have different
-meanings depending on whether the code is written in
-GNU Fortran (based on FORTRAN 77 and akin to Fortran 90)
-or VXT Fortran (more like VAX FORTRAN).
-
-The default is @samp{-fno-vxt}.
-@samp{-fvxt} specifies that the VXT Fortran interpretations
-for those constructs are to be chosen.
-
-@xref{VXT Fortran}, for more information.
-
-@cindex -fdollar-ok option
-@cindex options, -fdollar-ok
-@item -fdollar-ok
-@cindex dollar sign
-@cindex symbol names
-@cindex character set
-Allow @samp{$} as a valid character in a symbol name.
-
-@cindex -fno-backslash option
-@cindex options, -fno-backslash
-@item -fno-backslash
-@cindex backslash
-@cindex character constants
-@cindex Hollerith constants
-Specify that @samp{\} is not to be specially interpreted in character
-and Hollerith constants a la C and many UNIX Fortran compilers.
-
-For example, with @samp{-fbackslash} in effect, @samp{A\nB} specifies
-three characters, with the second one being newline.
-With @samp{-fno-backslash}, it specifies four characters,
-@samp{A}, @samp{\}, @samp{n}, and @samp{B}.
-
-Note that @code{g77} implements a fairly general form of backslash
-processing that is incompatible with the narrower forms supported
-by some other compilers.
-For example, @samp{'A\003B'} is a three-character string in @code{g77},
-whereas other compilers that support backslash might not support
-the three-octal-digit form, and thus treat that string as longer
-than three characters.
-
-@xref{Backslash in Constants}, for
-information on why @samp{-fbackslash} is the default
-instead of @samp{-fno-backslash}.
-
-@cindex -fno-ugly-args option
-@cindex options, -fno-ugly-args
-@item -fno-ugly-args
-Disallow passing Hollerith and typeless constants as actual
-arguments (for example, @samp{CALL FOO(4HABCD)}).
-
-@xref{Ugly Implicit Argument Conversion}, for more information.
-
-@cindex -fugly-assign option
-@cindex options, -fugly-assign
-@item -fugly-assign
-Use the same storage for a given variable regardless of
-whether it is used to hold an assigned-statement label
-(as in @samp{ASSIGN 10 TO I}) or used to hold numeric data
-(as in @samp{I = 3}).
-
-@xref{Ugly Assigned Labels}, for more information.
-
-@cindex -fugly-assumed option
-@cindex options, -fugly-assumed
-@item -fugly-assumed
-Assume any dummy array with a final dimension specified as @samp{1}
-is really an assumed-size array, as if @samp{*} had been specified
-for the final dimension instead of @samp{1}.
-
-For example, @samp{DIMENSION X(1)} is treated as if it
-had read @samp{DIMENSION X(*)}.
-
-@xref{Ugly Assumed-Size Arrays}, for more information.
-
-@cindex -fugly-comma option
-@cindex options, -fugly-comma
-@item -fugly-comma
-In an external-procedure invocation,
-treat a trailing comma in the argument list
-as specification of a trailing null argument,
-and treat an empty argument list
-as specification of a single null argument.
-
-For example, @samp{CALL FOO(,)} is treated as
-@samp{CALL FOO(%VAL(0), %VAL(0))}.
-That is, @emph{two} null arguments are specified
-by the procedure call when @samp{-fugly-comma} is in force.
-And @samp{F = FUNC()} is treated as @samp{F = FUNC(%VAL(0))}.
-
-The default behavior, @samp{-fno-ugly-comma}, is to ignore
-a single trailing comma in an argument list.
-So, by default, @samp{CALL FOO(X,)} is treated
-exactly the same as @samp{CALL FOO(X)}.
-
-@xref{Ugly Null Arguments}, for more information.
-
-@cindex -fugly-complex option
-@cindex options, -fugly-complex
-@item -fugly-complex
-Do not complain about @samp{REAL(@var{expr})} or
-@samp{AIMAG(@var{expr})} when @var{expr} is a @code{COMPLEX}
-type other than @code{COMPLEX(KIND=1)}---usually
-this is used to permit @code{COMPLEX(KIND=2)}
-(@code{DOUBLE COMPLEX}) operands.
-
-The @samp{-ff90} option controls the interpretation
-of this construct.
-
-@xref{Ugly Complex Part Extraction}, for more information.
-
-@cindex -fno-ugly-init option
-@cindex options, -fno-ugly-init
-@item -fno-ugly-init
-Disallow use of Hollerith and typeless constants as initial
-values (in @code{PARAMETER} and @code{DATA} statements), and
-use of character constants to
-initialize numeric types and vice versa.
-
-For example, @samp{DATA I/'F'/, CHRVAR/65/, J/4HABCD/} is disallowed by
-@samp{-fno-ugly-init}.
-
-@xref{Ugly Conversion of Initializers}, for more information.
-
-@cindex -fugly-logint option
-@cindex options, -fugly-logint
-@item -fugly-logint
-Treat @code{INTEGER} and @code{LOGICAL} variables and
-expressions as potential stand-ins for each other.
-
-For example, automatic conversion between @code{INTEGER} and
-@code{LOGICAL} is enabled, for many contexts, via this option.
-
-@xref{Ugly Integer Conversions}, for more information.
-
-@cindex -fonetrip option
-@cindex options, -fonetrip
-@item -fonetrip
-@cindex FORTRAN 66
-@cindex @code{DO} loops, one-trip
-@cindex one-trip @code{DO} loops
-@cindex @code{DO} loops, zero-trip
-@cindex zero-trip @code{DO} loops
-@cindex compatibility, FORTRAN 66
-Executable iterative @code{DO} loops are to be executed at
-least once each time they are reached.
-
-ANSI FORTRAN 77 and more recent versions of the Fortran standard
-specify that the body of an iterative @code{DO} loop is not executed
-if the number of iterations calculated from the parameters of the
-loop is less than 1.
-(For example, @samp{DO 10 I = 1, 0}.)
-Such a loop is called a @dfn{zero-trip loop}.
-
-Prior to ANSI FORTRAN 77, many compilers implemented @code{DO} loops
-such that the body of a loop would be executed at least once, even
-if the iteration count was zero.
-Fortran code written assuming this behavior is said to require
-@dfn{one-trip loops}.
-For example, some code written to the FORTRAN 66 standard
-expects this behavior from its @code{DO} loops, although that
-standard did not specify this behavior.
-
-The @samp{-fonetrip} option specifies that the source file(s) being
-compiled require one-trip loops.
-
-This option affects only those loops specified by the (iterative) @code{DO}
-statement and by implied-@code{DO} lists in I/O statements.
-Loops specified by implied-@code{DO} lists in @code{DATA} and
-specification (non-executable) statements are not affected.
-
-@cindex -ftypeless-boz option
-@cindex options, -ftypeless-boz
-@cindex prefix-radix constants
-@cindex constants, prefix-radix
-@cindex constants, types
-@cindex types, constants
-@item -ftypeless-boz
-Specifies that prefix-radix non-decimal constants, such as
-@samp{Z'ABCD'}, are typeless instead of @code{INTEGER(KIND=1)}.
-
-You can test for yourself whether a particular compiler treats
-the prefix form as @code{INTEGER(KIND=1)} or typeless by running the
-following program:
-
-@smallexample
-EQUIVALENCE (I, R)
-R = Z'ABCD1234'
-J = Z'ABCD1234'
-IF (J .EQ. I) PRINT *, 'Prefix form is TYPELESS'
-IF (J .NE. I) PRINT *, 'Prefix form is INTEGER'
-END
-@end smallexample
-
-Reports indicate that many compilers process this form as
-@code{INTEGER(KIND=1)}, though a few as typeless, and at least one
-based on a command-line option specifying some kind of
-compatibility.
-
-@cindex -fintrin-case-initcap option
-@cindex options, -fintrin-case-initcap
-@item -fintrin-case-initcap
-@cindex -fintrin-case-upper option
-@cindex options, -fintrin-case-upper
-@item -fintrin-case-upper
-@cindex -fintrin-case-lower option
-@cindex options, -fintrin-case-lower
-@item -fintrin-case-lower
-@cindex -fintrin-case-any option
-@cindex options, -fintrin-case-any
-@item -fintrin-case-any
-Specify expected case for intrinsic names.
-@samp{-fintrin-case-lower} is the default.
-
-@cindex -fmatch-case-initcap option
-@cindex options, -fmatch-case-initcap
-@item -fmatch-case-initcap
-@cindex -fmatch-case-upper option
-@cindex options, -fmatch-case-upper
-@item -fmatch-case-upper
-@cindex -fmatch-case-lower option
-@cindex options, -fmatch-case-lower
-@item -fmatch-case-lower
-@cindex -fmatch-case-any option
-@cindex options, -fmatch-case-any
-@item -fmatch-case-any
-Specify expected case for keywords.
-@samp{-fmatch-case-lower} is the default.
-
-@cindex -fsource-case-upper option
-@cindex options, -fsource-case-upper
-@item -fsource-case-upper
-@cindex -fsource-case-lower option
-@cindex options, -fsource-case-lower
-@item -fsource-case-lower
-@cindex -fsource-case-preserve option
-@cindex options, -fsource-case-preserve
-@item -fsource-case-preserve
-Specify whether source text other than character and Hollerith constants
-is to be translated to uppercase, to lowercase, or preserved as is.
-@samp{-fsource-case-lower} is the default.
-
-@cindex -fsymbol-case-initcap option
-@cindex options, -fsymbol-case-initcap
-@item -fsymbol-case-initcap
-@cindex -fsymbol-case-upper option
-@cindex options, -fsymbol-case-upper
-@item -fsymbol-case-upper
-@cindex -fsymbol-case-lower option
-@cindex options, -fsymbol-case-lower
-@item -fsymbol-case-lower
-@cindex -fsymbol-case-any option
-@cindex options, -fsymbol-case-any
-@item -fsymbol-case-any
-Specify valid cases for user-defined symbol names.
-@samp{-fsymbol-case-any} is the default.
-
-@cindex -fcase-strict-upper option
-@cindex options, -fcase-strict-upper
-@item -fcase-strict-upper
-Same as @samp{-fintrin-case-upper -fmatch-case-upper -fsource-case-preserve
--fsymbol-case-upper}.
-(Requires all pertinent source to be in uppercase.)
-
-@cindex -fcase-strict-lower option
-@cindex options, -fcase-strict-lower
-@item -fcase-strict-lower
-Same as @samp{-fintrin-case-lower -fmatch-case-lower -fsource-case-preserve
--fsymbol-case-lower}.
-(Requires all pertinent source to be in lowercase.)
-
-@cindex -fcase-initcap option
-@cindex options, -fcase-initcap
-@item -fcase-initcap
-Same as @samp{-fintrin-case-initcap -fmatch-case-initcap -fsource-case-preserve
--fsymbol-case-initcap}.
-(Requires all pertinent source to be in initial capitals,
-as in @samp{Print *,SqRt(Value)}.)
-
-@cindex -fcase-upper option
-@cindex options, -fcase-upper
-@item -fcase-upper
-Same as @samp{-fintrin-case-any -fmatch-case-any -fsource-case-upper
--fsymbol-case-any}.
-(Maps all pertinent source to uppercase.)
-
-@cindex -fcase-lower option
-@cindex options, -fcase-lower
-@item -fcase-lower
-Same as @samp{-fintrin-case-any -fmatch-case-any -fsource-case-lower
--fsymbol-case-any}.
-(Maps all pertinent source to lowercase.)
-
-@cindex -fcase-preserve option
-@cindex options, -fcase-preserve
-@item -fcase-preserve
-Same as @samp{-fintrin-case-any -fmatch-case-any -fsource-case-preserve
--fsymbol-case-any}.
-(Preserves all case in user-defined symbols,
-while allowing any-case matching of intrinsics and keywords.
-For example, @samp{call Foo(i,I)} would pass two @emph{different}
-variables named @samp{i} and @samp{I} to a procedure named @samp{Foo}.)
-
-@cindex -fbadu77-intrinsics-delete option
-@cindex options, -fbadu77-intrinsics-delete
-@item -fbadu77-intrinsics-delete
-@cindex -fbadu77-intrinsics-hide option
-@cindex options, -fbadu77-intrinsics-hide
-@item -fbadu77-intrinsics-hide
-@cindex -fbadu77-intrinsics-disable option
-@cindex options, -fbadu77-intrinsics-disable
-@item -fbadu77-intrinsics-disable
-@cindex -fbadu77-intrinsics-enable option
-@cindex options, -fbadu77-intrinsics-enable
-@item -fbadu77-intrinsics-enable
-@cindex @code{badu77} intrinsics
-@cindex intrinsics, @code{badu77}
-Specify status of UNIX intrinsics having inappropriate forms.
-@samp{-fbadu77-intrinsics-enable} is the default.
-@xref{Intrinsic Groups}.
-
-@cindex -ff2c-intrinsics-delete option
-@cindex options, -ff2c-intrinsics-delete
-@item -ff2c-intrinsics-delete
-@cindex -ff2c-intrinsics-hide option
-@cindex options, -ff2c-intrinsics-hide
-@item -ff2c-intrinsics-hide
-@cindex -ff2c-intrinsics-disable option
-@cindex options, -ff2c-intrinsics-disable
-@item -ff2c-intrinsics-disable
-@cindex -ff2c-intrinsics-enable option
-@cindex options, -ff2c-intrinsics-enable
-@item -ff2c-intrinsics-enable
-@cindex @code{f2c} intrinsics
-@cindex intrinsics, @code{f2c}
-Specify status of f2c-specific intrinsics.
-@samp{-ff2c-intrinsics-enable} is the default.
-@xref{Intrinsic Groups}.
-
-@cindex -ff90-intrinsics-delete option
-@cindex options, -ff90-intrinsics-delete
-@item -ff90-intrinsics-delete
-@cindex -ff90-intrinsics-hide option
-@cindex options, -ff90-intrinsics-hide
-@item -ff90-intrinsics-hide
-@cindex -ff90-intrinsics-disable option
-@cindex options, -ff90-intrinsics-disable
-@item -ff90-intrinsics-disable
-@cindex -ff90-intrinsics-enable option
-@cindex options, -ff90-intrinsics-enable
-@item -ff90-intrinsics-enable
-@cindex Fortran 90, intrinsics
-@cindex intrinsics, Fortran 90
-Specify status of F90-specific intrinsics.
-@samp{-ff90-intrinsics-enable} is the default.
-@xref{Intrinsic Groups}.
-
-@cindex -fgnu-intrinsics-delete option
-@cindex options, -fgnu-intrinsics-delete
-@item -fgnu-intrinsics-delete
-@cindex -fgnu-intrinsics-hide option
-@cindex options, -fgnu-intrinsics-hide
-@item -fgnu-intrinsics-hide
-@cindex -fgnu-intrinsics-disable option
-@cindex options, -fgnu-intrinsics-disable
-@item -fgnu-intrinsics-disable
-@cindex -fgnu-intrinsics-enable option
-@cindex options, -fgnu-intrinsics-enable
-@item -fgnu-intrinsics-enable
-@cindex Digital Fortran features
-@cindex @code{COMPLEX} intrinsics
-@cindex intrinsics, @code{COMPLEX}
-Specify status of Digital's COMPLEX-related intrinsics.
-@samp{-fgnu-intrinsics-enable} is the default.
-@xref{Intrinsic Groups}.
-
-@cindex -fmil-intrinsics-delete option
-@cindex options, -fmil-intrinsics-delete
-@item -fmil-intrinsics-delete
-@cindex -fmil-intrinsics-hide option
-@cindex options, -fmil-intrinsics-hide
-@item -fmil-intrinsics-hide
-@cindex -fmil-intrinsics-disable option
-@cindex options, -fmil-intrinsics-disable
-@item -fmil-intrinsics-disable
-@cindex -fmil-intrinsics-enable option
-@cindex options, -fmil-intrinsics-enable
-@item -fmil-intrinsics-enable
-@cindex MIL-STD 1753
-@cindex intrinsics, MIL-STD 1753
-Specify status of MIL-STD-1753-specific intrinsics.
-@samp{-fmil-intrinsics-enable} is the default.
-@xref{Intrinsic Groups}.
-
-@cindex -funix-intrinsics-delete option
-@cindex options, -funix-intrinsics-delete
-@item -funix-intrinsics-delete
-@cindex -funix-intrinsics-hide option
-@cindex options, -funix-intrinsics-hide
-@item -funix-intrinsics-hide
-@cindex -funix-intrinsics-disable option
-@cindex options, -funix-intrinsics-disable
-@item -funix-intrinsics-disable
-@cindex -funix-intrinsics-enable option
-@cindex options, -funix-intrinsics-enable
-@item -funix-intrinsics-enable
-@cindex UNIX intrinsics
-@cindex intrinsics, UNIX
-Specify status of UNIX intrinsics.
-@samp{-funix-intrinsics-enable} is the default.
-@xref{Intrinsic Groups}.
-
-@cindex -fvxt-intrinsics-delete option
-@cindex options, -fvxt-intrinsics-delete
-@item -fvxt-intrinsics-delete
-@cindex -fvxt-intrinsics-hide option
-@cindex options, -fvxt-intrinsics-hide
-@item -fvxt-intrinsics-hide
-@cindex -fvxt-intrinsics-disable option
-@cindex options, -fvxt-intrinsics-disable
-@item -fvxt-intrinsics-disable
-@cindex -fvxt-intrinsics-enable option
-@cindex options, -fvxt-intrinsics-enable
-@item -fvxt-intrinsics-enable
-@cindex VXT intrinsics
-@cindex intrinsics, VXT
-Specify status of VXT intrinsics.
-@samp{-fvxt-intrinsics-enable} is the default.
-@xref{Intrinsic Groups}.
-
-@cindex -ffixed-line-length-@var{n} option
-@cindex options, -ffixed-line-length-@var{n}
-@item -ffixed-line-length-@var{n}
-@cindex source file format
-@cindex lines, length
-@cindex length of source lines
-@cindex fixed form
-@cindex limits, lengths of source lines
-Set column after which characters are ignored in typical fixed-form
-lines in the source file, and through which spaces are assumed (as
-if padded to that length) after the ends of short fixed-form lines.
-
-@cindex card image
-@cindex extended-source option
-Popular values for @var{n} include 72 (the
-standard and the default), 80 (card image), and 132 (corresponds
-to ``extended-source'' options in some popular compilers).
-@var{n} may be @samp{none}, meaning that the entire line is meaningful
-and that continued character constants never have implicit spaces appended
-to them to fill out the line.
-@samp{-ffixed-line-length-0} means the same thing as
-@samp{-ffixed-line-length-none}.
-
-@xref{Source Form}, for more information.
-@end table
-
-@node Warning Options
-@section Options to Request or Suppress Warnings
-@cindex options, warnings
-@cindex warnings, suppressing
-@cindex messages, warning
-@cindex suppressing warnings
-
-Warnings are diagnostic messages that report constructions which
-are not inherently erroneous but which are risky or suggest there
-might have been an error.
-
-You can request many specific warnings with options beginning @samp{-W},
-for example @samp{-Wimplicit} to request warnings on implicit
-declarations. Each of these specific warning options also has a
-negative form beginning @samp{-Wno-} to turn off warnings;
-for example, @samp{-Wno-implicit}. This manual lists only one of the
-two forms, whichever is not the default.
-
-These options control the amount and kinds of warnings produced by GNU
-Fortran:
-
-@table @code
-@cindex syntax checking
-@cindex -fsyntax-only option
-@cindex options, -fsyntax-only
-@item -fsyntax-only
-Check the code for syntax errors, but don't do anything beyond that.
-
-@cindex -pedantic option
-@cindex options, -pedantic
-@item -pedantic
-Issue warnings for uses of extensions to ANSI FORTRAN 77.
-@samp{-pedantic} also applies to C-language constructs where they
-occur in GNU Fortran source files, such as use of @samp{\e} in a
-character constant within a directive like @samp{#include}.
-
-Valid ANSI FORTRAN 77 programs should compile properly with or without
-this option.
-However, without this option, certain GNU extensions and traditional
-Fortran features are supported as well.
-With this option, many of them are rejected.
-
-Some users try to use @samp{-pedantic} to check programs for strict ANSI
-conformance.
-They soon find that it does not do quite what they want---it finds some
-non-ANSI practices, but not all.
-However, improvements to @code{g77} in this area are welcome.
-
-@cindex -pedantic-errors option
-@cindex options, -pedantic-errors
-@item -pedantic-errors
-Like @samp{-pedantic}, except that errors are produced rather than
-warnings.
-
-@cindex -fpedantic option
-@cindex options, -fpedantic
-@item -fpedantic
-Like @samp{-pedantic}, but applies only to Fortran constructs.
-
-@cindex -w option
-@cindex options, -w
-@item -w
-Inhibit all warning messages.
-
-@cindex -Wno-globals option
-@cindex options, -Wno-globals
-@item -Wno-globals
-@cindex global names, warning
-@cindex warnings, global names
-Inhibit warnings about use of a name as both a global name
-(a subroutine, function, or block data program unit, or a
-common block) and implicitly as the name of an intrinsic
-in a source file.
-
-Also inhibit warnings about inconsistent invocations and/or
-definitions of global procedures (function and subroutines).
-Such inconsistencies include different numbers of arguments
-and different types of arguments.
-
-@cindex -Wimplicit option
-@cindex options, -Wimplicit
-@item -Wimplicit
-@cindex implicit declaration, warning
-@cindex warnings, implicit declaration
-@cindex -u option
-@cindex /WARNINGS=DECLARATIONS switch
-@cindex IMPLICIT NONE, similar effect
-@cindex effecting IMPLICIT NONE
-Warn whenever a variable, array, or function is implicitly
-declared.
-Has an effect similar to using the @code{IMPLICIT NONE} statement
-in every program unit.
-(Some Fortran compilers provide this feature by an option
-named @samp{-u} or @samp{/WARNINGS=DECLARATIONS}.)
-
-@cindex -Wunused option
-@cindex options, -Wunused
-@item -Wunused
-@cindex unused variables
-@cindex variables, unused
-Warn whenever a variable is unused aside from its declaration.
-
-@cindex -Wuninitialized option
-@cindex options, -Wuninitialized
-@item -Wuninitialized
-@cindex uninitialized variables
-@cindex variables, uninitialized
-Warn whenever an automatic variable is used without first being initialized.
-
-These warnings are possible only in optimizing compilation,
-because they require data-flow information that is computed only
-when optimizing. If you don't specify @samp{-O}, you simply won't
-get these warnings.
-
-These warnings occur only for variables that are candidates for
-register allocation. Therefore, they do not occur for a variable
-@c that is declared @code{VOLATILE}, or
-whose address is taken, or whose size
-is other than 1, 2, 4 or 8 bytes. Also, they do not occur for
-arrays, even when they are in registers.
-
-Note that there might be no warning about a variable that is used only
-to compute a value that itself is never used, because such
-computations may be deleted by data-flow analysis before the warnings
-are printed.
-
-These warnings are made optional because GNU Fortran is not smart
-enough to see all the reasons why the code might be correct
-despite appearing to have an error. Here is one example of how
-this can happen:
-
-@example
-SUBROUTINE DISPAT(J)
-IF (J.EQ.1) I=1
-IF (J.EQ.2) I=4
-IF (J.EQ.3) I=5
-CALL FOO(I)
-END
-@end example
-
-@noindent
-If the value of @code{J} is always 1, 2 or 3, then @code{I} is
-always initialized, but GNU Fortran doesn't know this. Here is
-another common case:
-
-@example
-SUBROUTINE MAYBE(FLAG)
-LOGICAL FLAG
-IF (FLAG) VALUE = 9.4
-@dots{}
-IF (FLAG) PRINT *, VALUE
-END
-@end example
-
-@noindent
-This has no bug because @code{VALUE} is used only if it is set.
-
-@cindex -Wall option
-@cindex options, -Wall
-@item -Wall
-@cindex all warnings
-@cindex warnings, all
-The @samp{-Wunused} and @samp{-Wuninitialized} options combined.
-These are all the
-options which pertain to usage that we recommend avoiding and that we
-believe is easy to avoid.
-(As more warnings are added to @code{g77}, some might
-be added to the list enabled by @samp{-Wall}.)
-@end table
-
-The remaining @samp{-W@dots{}} options are not implied by @samp{-Wall}
-because they warn about constructions that we consider reasonable to
-use, on occasion, in clean programs.
-
-@table @code
-@c @item -W
-@c Print extra warning messages for these events:
-@c
-@c @itemize @bullet
-@c @item
-@c If @samp{-Wall} or @samp{-Wunused} is also specified, warn about unused
-@c arguments.
-@c
-@c @end itemize
-@c
-@cindex -Wsurprising option
-@cindex options, -Wsurprising
-@item -Wsurprising
-Warn about ``suspicious'' constructs that are interpreted
-by the compiler in a way that might well be surprising to
-someone reading the code.
-These differences can result in subtle, compiler-dependent
-(even machine-dependent) behavioral differences.
-The constructs warned about include:
-
-@itemize @bullet
-@item
-Expressions having two arithmetic operators in a row, such
-as @samp{X*-Y}.
-Such a construct is nonstandard, and can produce
-unexpected results in more complicated situations such
-as @samp{X**-Y*Z}.
-@code{g77}, along with many other compilers, interprets
-this example differently than many programmers, and a few
-other compilers.
-Specifically, @code{g77} interprets @samp{X**-Y*Z} as
-@samp{(X**(-Y))*Z}, while others might think it should
-be interpreted as @samp{X**(-(Y*Z))}.
-
-A revealing example is the constant expression @samp{2**-2*1.},
-which @code{g77} evaluates to .25, while others might evaluate
-it to 0., the difference resulting from the way precedence affects
-type promotion.
-
-(The @samp{-fpedantic} option also warns about expressions
-having two arithmetic operators in a row.)
-
-@item
-Expressions with a unary minus followed by an operand and then
-a binary operator other than plus or minus.
-For example, @samp{-2**2} produces a warning, because
-the precedence is @samp{-(2**2)}, yielding -4, not
-@samp{(-2)**2}, which yields 4, and which might represent
-what a programmer expects.
-
-An example of an expression producing different results
-in a surprising way is @samp{-I*S}, where @var{I} holds
-the value @samp{-2147483648} and @var{S} holds @samp{0.5}.
-On many systems, negating @var{I} results in the same
-value, not a positive number, because it is already the
-lower bound of what an @code{INTEGER(KIND=1)} variable can hold.
-So, the expression evaluates to a positive number, while
-the ``expected'' interpretation, @samp{(-I)*S}, would
-evaluate to a negative number.
-
-Even cases such as @samp{-I*J} produce warnings,
-even though, in most configurations and situations,
-there is no computational difference between the
-results of the two interpretations---the purpose
-of this warning is to warn about differing interpretations
-and encourage a better style of coding, not to identify
-only those places where bugs might exist in the user's
-code.
-
-@cindex DO statement
-@cindex statements, DO
-@item
-@code{DO} loops with @code{DO} variables that are not
-of integral type---that is, using @code{REAL}
-variables as loop control variables.
-Although such loops can be written to work in the
-``obvious'' way, the way @code{g77} is required by the
-Fortran standard to interpret such code is likely to
-be quite different from the way many programmers expect.
-(This is true of all @code{DO} loops, but the differences
-are pronounced for non-integral loop control variables.)
-
-@xref{Loops}, for more information.
-@end itemize
-
-@cindex -Werror option
-@cindex options, -Werror
-@item -Werror
-Make all warnings into errors.
-
-@cindex -W option
-@cindex options, -W
-@item -W
-@cindex extra warnings
-@cindex warnings, extra
-Turns on ``extra warnings'' and, if optimization is specified
-via @samp{-O}, the @samp{-Wuninitialized} option.
-(This might change in future versions of @code{g77}.)
-
-``Extra warnings'' are issued for:
-
-@itemize @bullet
-@item
-@cindex unused parameters
-@cindex parameters, unused
-@cindex unused arguments
-@cindex arguments, unused
-@cindex unused dummies
-@cindex dummies, unused
-Unused parameters to a procedure (when @samp{-Wunused} also is
-specified).
-
-@item
-@cindex overflow
-Overflows involving floating-point constants (not available
-for certain configurations).
-@end itemize
-@end table
-
-@xref{Warning Options,,Options to Request or Suppress Warnings,
-gcc,Using and Porting GNU CC}, for information on more options offered
-by the GBE shared by @code{g77}, @code{gcc}, and other GNU compilers.
-
-Some of these have no effect when compiling programs written in Fortran:
-
-@table @code
-@cindex -Wcomment option
-@cindex options, -Wcomment
-@item -Wcomment
-@cindex -Wformat option
-@cindex options, -Wformat
-@item -Wformat
-@cindex -Wparentheses option
-@cindex options, -Wparentheses
-@item -Wparentheses
-@cindex -Wswitch option
-@cindex options, -Wswitch
-@item -Wswitch
-@cindex -Wtraditional option
-@cindex options, -Wtraditional
-@item -Wtraditional
-@cindex -Wshadow option
-@cindex options, -Wshadow
-@item -Wshadow
-@cindex -Wid-clash-@var{len} option
-@cindex options, -Wid-clash-@var{len}
-@item -Wid-clash-@var{len}
-@cindex -Wlarger-than-@var{len} option
-@cindex options, -Wlarger-than-@var{len}
-@item -Wlarger-than-@var{len}
-@cindex -Wconversion option
-@cindex options, -Wconversion
-@item -Wconversion
-@cindex -Waggregate-return option
-@cindex options, -Waggregate-return
-@item -Waggregate-return
-@cindex -Wredundant-decls option
-@cindex options, -Wredundant-decls
-@item -Wredundant-decls
-@cindex unsupported warnings
-@cindex warnings, unsupported
-These options all could have some relevant meaning for
-GNU Fortran programs, but are not yet supported.
-@end table
-
-@node Debugging Options
-@section Options for Debugging Your Program or GNU Fortran
-@cindex options, debugging
-@cindex debugging information options
-
-GNU Fortran has various special options that are used for debugging
-either your program or @code{g77}.
-
-@table @code
-@cindex -g option
-@cindex options, -g
-@item -g
-Produce debugging information in the operating system's native format
-(stabs, COFF, XCOFF, or DWARF). GDB can work with this debugging
-information.
-@end table
-
-@xref{Debugging Options,,Options for Debugging Your Program or GNU CC,
-gcc,Using and Porting GNU CC}, for more information on debugging options.
-
-@node Optimize Options
-@section Options That Control Optimization
-@cindex optimize options
-@cindex options, optimization
-
-Most Fortran users will want to use no optimization when
-developing and testing programs, and use @samp{-O} or @samp{-O2} when
-compiling programs for late-cycle testing and for production use.
-However, note that certain diagnostics---such as for uninitialized
-variables---depend on the flow analysis done by @samp{-O}, i.e.@: you
-must use @samp{-O} or @samp{-O2} to get such diagnostics.
-
-The following flags have particular applicability when
-compiling Fortran programs:
-
-@table @code
-@cindex -malign-double option
-@cindex options, -malign-double
-@item -malign-double
-(Intel x86 architecture only.)
-
-Noticeably improves performance of @code{g77} programs making
-heavy use of @code{REAL(KIND=2)} (@code{DOUBLE PRECISION}) data
-on some systems.
-In particular, systems using Pentium, Pentium Pro, 586, and
-686 implementations
-of the i386 architecture execute programs faster when
-@code{REAL(KIND=2)} (@code{DOUBLE PRECISION}) data are
-aligned on 64-bit boundaries
-in memory.
-
-This option can, at least, make benchmark results more consistent
-across various system configurations, versions of the program,
-and data sets.
-
-@emph{Note:} The warning in the @code{gcc} documentation about
-this option does not apply, generally speaking, to Fortran
-code compiled by @code{g77}.
-
-@xref{Aligned Data}, for more information on alignment issues.
-
-@emph{Also also note:} The negative form of @samp{-malign-double}
-is @samp{-mno-align-double}, not @samp{-benign-double}.
-
-@cindex -ffloat-store option
-@cindex options, -ffloat-store
-@item -ffloat-store
-@cindex IEEE 754 conformance
-@cindex conformance, IEEE 754
-@cindex floating-point, precision
-Might help a Fortran program that depends on exact IEEE conformance on
-some machines, but might slow down a program that doesn't.
-
-This option is effective when the floating-point unit is set to work in
-IEEE 854 `extended precision'---as it typically is on x86 and m68k GNU
-systems---rather than IEEE 754 double precision. @samp{-ffloat-store}
-tries to remove the extra precision by spilling data from floating-point
-registers into memory and this typically involves a big performance
-hit. However, it doesn't affect intermediate results, so that it is
-only partially effective. `Excess precision' is avoided in code like:
-@smallexample
-a = b + c
-d = a * e
-@end smallexample
-but not in code like:
-@smallexample
- d = (b + c) * e
-@end smallexample
-
-For another, potentially better, way of controlling the precision,
-see @ref{Floating-point precision}.
-
-@cindex -fforce-mem option
-@cindex options, -fforce-mem
-@item -fforce-mem
-@cindex -fforce-addr option
-@cindex options, -fforce-addr
-@item -fforce-addr
-@cindex loops, speeding up
-@cindex speed, of loops
-Might improve optimization of loops.
-
-@cindex -fno-inline option
-@cindex options, -fno-inline
-@item -fno-inline
-@cindex in-line code
-@cindex compilation, in-line
-@c DL: Only relevant for -O3?
-Don't compile statement functions inline.
-Might reduce the size of a program unit---which might be at
-expense of some speed (though it should compile faster).
-Note that if you are not optimizing, no functions can be expanded inline.
-
-@cindex -ffast-math option
-@cindex options, -ffast-math
-@item -ffast-math
-@cindex IEEE 754 conformance
-@cindex conformance, IEEE 754
-Might allow some programs designed to not be too dependent
-on IEEE behavior for floating-point to run faster, or die trying.
-Sets @samp{-funsafe-math-optimizations}, and
-@samp{-fno-trapping-math}.
-
-@cindex -funsafe-math-optimizations option
-@cindex options, -funsafe-math-optimizations
-@item -funsafe-math-optimizations
-Allow optimizations that may be give incorrect results
-for certain IEEE inputs.
-
-@cindex -fno-trapping-math option
-@cindex options, -fno-trapping-math
-@item -fno-trapping-math
-Allow the compiler to assume that floating-point arithmetic
-will not generate traps on any inputs. This is useful, for
-example, when running a program using IEEE "non-stop"
-floating-point arithmetic.
-
-@cindex -fstrength-reduce option
-@cindex options, -fstrength-reduce
-@item -fstrength-reduce
-@cindex loops, speeding up
-@cindex speed, of loops
-@c DL: normally defaulted?
-Might make some loops run faster.
-
-@cindex -frerun-cse-after-loop option
-@cindex options, -frerun-cse-after-loop
-@item -frerun-cse-after-loop
-@cindex -fexpensive-optimizations option
-@cindex options, -fexpensive-optimizations
-@c DL: This is -O2?
-@item -fexpensive-optimizations
-@cindex -fdelayed-branch option
-@cindex options, -fdelayed-branch
-@item -fdelayed-branch
-@cindex -fschedule-insns option
-@cindex options, -fschedule-insns
-@item -fschedule-insns
-@cindex -fschedule-insns2 option
-@cindex options, -fschedule-insns2
-@item -fschedule-insns2
-@cindex -fcaller-saves option
-@cindex options, -fcaller-saves
-@item -fcaller-saves
-Might improve performance on some code.
-
-@cindex -funroll-loops option
-@cindex options, -funroll-loops
-@item -funroll-loops
-@cindex loops, unrolling
-@cindex unrolling loops
-@cindex loops, optimizing
-@cindex indexed (iterative) @code{DO}
-@cindex iterative @code{DO}
-@c DL: fixme: Craig doesn't like `indexed' but f95 doesn't seem to
-@c provide a suitable term
-@c CB: I've decided on `iterative', for the time being, and changed
-@c my previous, rather bizarre, use of `imperative' to that
-@c (though `precomputed-trip' would be a more precise adjective)
-Typically improves performance on code using iterative @code{DO} loops by
-unrolling them and is probably generally appropriate for Fortran, though
-it is not turned on at any optimization level.
-Note that outer loop unrolling isn't done specifically; decisions about
-whether to unroll a loop are made on the basis of its instruction count.
-
-@c DL: Fixme: This should obviously go somewhere else...
-Also, no `loop discovery'@footnote{@dfn{loop discovery} refers to the
-process by which a compiler, or indeed any reader of a program,
-determines which portions of the program are more likely to be executed
-repeatedly as it is being run. Such discovery typically is done early
-when compiling using optimization techniques, so the ``discovered''
-loops get more attention---and more run-time resources, such as
-registers---from the compiler. It is easy to ``discover'' loops that are
-constructed out of looping constructs in the language
-(such as Fortran's @code{DO}). For some programs, ``discovering'' loops
-constructed out of lower-level constructs (such as @code{IF} and
-@code{GOTO}) can lead to generation of more optimal code
-than otherwise.} is done, so only loops written with @code{DO}
-benefit from loop optimizations, including---but not limited
-to---unrolling. Loops written with @code{IF} and @code{GOTO} are not
-currently recognized as such. This option unrolls only iterative
-@code{DO} loops, not @code{DO WHILE} loops.
-
-@cindex -funroll-all-loops option
-@cindex options, -funroll-all-loops
-@cindex DO WHILE
-@item -funroll-all-loops
-@c DL: Check my understanding of -funroll-all-loops v. -funroll-loops is correct.
-Probably improves performance on code using @code{DO WHILE} loops by
-unrolling them in addition to iterative @code{DO} loops. In the absence
-of @code{DO WHILE}, this option is equivalent to @samp{-funroll-loops}
-but possibly slower.
-
-@item -fno-move-all-movables
-@cindex -fno-move-all-movables option
-@cindex options, -fno-move-all-movables
-@item -fno-reduce-all-givs
-@cindex -fno-reduce-all-givs option
-@cindex options, -fno-reduce-all-givs
-@item -fno-rerun-loop-opt
-@cindex -fno-rerun-loop-opt option
-@cindex options, -fno-rerun-loop-opt
-@emph{Version info:}
-These options are not supported by
-versions of @code{g77} based on @code{gcc} version 2.8.
-
-Each of these might improve performance on some code.
-
-Analysis of Fortran code optimization and the resulting
-optimizations triggered by the above options were
-contributed by Toon Moene (@email{toon@@moene.indiv.nluug.nl}).
-
-These three options are intended to be removed someday, once
-they have helped determine the efficacy of various
-approaches to improving the performance of Fortran code.
-
-Please let us know how use of these options affects
-the performance of your production code.
-We're particularly interested in code that runs faster
-when these options are @emph{disabled}, and in
-non-Fortran code that benefits when they are
-@emph{enabled} via the above @code{gcc} command-line options.
-@end table
-
-@xref{Optimize Options,,Options That Control Optimization,
-gcc,Using and Porting GNU CC}, for more information on options
-to optimize the generated machine code.
-
-@node Preprocessor Options
-@section Options Controlling the Preprocessor
-@cindex preprocessor options
-@cindex options, preprocessor
-@cindex cpp program
-@cindex programs, cpp
-
-These options control the C preprocessor, which is run on each C source
-file before actual compilation.
-
-@xref{Preprocessor Options,,Options Controlling the Preprocessor,
-gcc,Using and Porting GNU CC}, for information on C preprocessor options.
-
-@cindex INCLUDE directive
-@cindex directive, INCLUDE
-Some of these options also affect how @code{g77} processes the
-@code{INCLUDE} directive.
-Since this directive is processed even when preprocessing
-is not requested, it is not described in this section.
-@xref{Directory Options,,Options for Directory Search}, for
-information on how @code{g77} processes the @code{INCLUDE} directive.
-
-However, the @code{INCLUDE} directive does not apply
-preprocessing to the contents of the included file itself.
-
-Therefore, any file that contains preprocessor directives
-(such as @code{#include}, @code{#define}, and @code{#if})
-must be included via the @code{#include} directive, not
-via the @code{INCLUDE} directive.
-Therefore, any file containing preprocessor directives,
-if included, is necessarily included by a file that itself
-contains preprocessor directives.
-
-@node Directory Options
-@section Options for Directory Search
-@cindex directory, options
-@cindex options, directory search
-@cindex search path
-
-These options affect how the @code{cpp} preprocessor searches
-for files specified via the @code{#include} directive.
-Therefore, when compiling Fortran programs, they are meaningful
-when the preprocessor is used.
-
-@cindex INCLUDE directive
-@cindex directive, INCLUDE
-Some of these options also affect how @code{g77} searches
-for files specified via the @code{INCLUDE} directive,
-although files included by that directive are not,
-themselves, preprocessed.
-These options are:
-
-@table @code
-@cindex -I- option
-@cindex options, -I-
-@item -I-
-@cindex -Idir option
-@cindex options, -Idir
-@item -I@var{dir}
-@cindex directory, search paths for inclusion
-@cindex inclusion, directory search paths for
-@cindex search paths, for included files
-@cindex paths, search
-These affect interpretation of the @code{INCLUDE} directive
-(as well as of the @code{#include} directive of the @code{cpp}
-preprocessor).
-
-Note that @samp{-I@var{dir}} must be specified @emph{without} any
-spaces between @samp{-I} and the directory name---that is,
-@samp{-Ifoo/bar} is valid, but @samp{-I foo/bar}
-is rejected by the @code{g77} compiler (though the preprocessor supports
-the latter form).
-@c this is due to toplev.c's inflexible option processing
-Also note that the general behavior of @samp{-I} and
-@code{INCLUDE} is pretty much the same as of @samp{-I} with
-@code{#include} in the @code{cpp} preprocessor, with regard to
-looking for @file{header.gcc} files and other such things.
-
-@xref{Directory Options,,Options for Directory Search,
-gcc,Using and Porting GNU CC}, for information on the @samp{-I} option.
-@end table
-
-@node Code Gen Options
-@section Options for Code Generation Conventions
-@cindex code generation, conventions
-@cindex options, code generation
-@cindex run-time, options
-
-These machine-independent options control the interface conventions
-used in code generation.
-
-Most of them have both positive and negative forms; the negative form
-of @samp{-ffoo} would be @samp{-fno-foo}. In the table below, only
-one of the forms is listed---the one which is not the default. You
-can figure out the other form by either removing @samp{no-} or adding
-it.
-
-@table @code
-@cindex -fno-automatic option
-@cindex options, -fno-automatic
-@item -fno-automatic
-@cindex SAVE statement
-@cindex statements, SAVE
-Treat each program unit as if the @code{SAVE} statement was specified
-for every local variable and array referenced in it.
-Does not affect common blocks.
-(Some Fortran compilers provide this option under
-the name @samp{-static}.)
-
-@cindex -finit-local-zero option
-@cindex options, -finit-local-zero
-@item -finit-local-zero
-@cindex DATA statement
-@cindex statements, DATA
-@cindex initialization, of local variables
-@cindex variables, initialization of
-@cindex uninitialized variables
-@cindex variables, uninitialized
-Specify that variables and arrays that are local to a program unit
-(not in a common block and not passed as an argument) are to be initialized
-to binary zeros.
-
-Since there is a run-time penalty for initialization of variables
-that are not given the @code{SAVE} attribute, it might be a
-good idea to also use @samp{-fno-automatic} with @samp{-finit-local-zero}.
-
-@cindex -fno-f2c option
-@cindex options, -fno-f2c
-@item -fno-f2c
-@cindex @code{f2c} compatibility
-@cindex compatibility, @code{f2c}
-Do not generate code designed to be compatible with code generated
-by @code{f2c}; use the GNU calling conventions instead.
-
-The @code{f2c} calling conventions require functions that return
-type @code{REAL(KIND=1)} to actually return the C type @code{double},
-and functions that return type @code{COMPLEX} to return the
-values via an extra argument in the calling sequence that points
-to where to store the return value.
-Under the GNU calling conventions, such functions simply return
-their results as they would in GNU C---@code{REAL(KIND=1)} functions
-return the C type @code{float}, and @code{COMPLEX} functions
-return the GNU C type @code{complex} (or its @code{struct}
-equivalent).
-
-This does not affect the generation of code that interfaces with the
-@code{libg2c} library.
-
-However, because the @code{libg2c} library uses @code{f2c}
-calling conventions, @code{g77} rejects attempts to pass
-intrinsics implemented by routines in this library as actual
-arguments when @samp{-fno-f2c} is used, to avoid bugs when
-they are actually called by code expecting the GNU calling
-conventions to work.
-
-For example, @samp{INTRINSIC ABS;CALL FOO(ABS)} is
-rejected when @samp{-fno-f2c} is in force.
-(Future versions of the @code{g77} run-time library might
-offer routines that provide GNU-callable versions of the
-routines that implement the @code{f2c}-callable intrinsics
-that may be passed as actual arguments, so that
-valid programs need not be rejected when @samp{-fno-f2c}
-is used.)
-
-@strong{Caution:} If @samp{-fno-f2c} is used when compiling any
-source file used in a program, it must be used when compiling
-@emph{all} Fortran source files used in that program.
-
-@c seems kinda dumb to tell people about an option they can't use -- jcb
-@c then again, we want users building future-compatible libraries with it.
-@cindex -ff2c-library option
-@cindex options, -ff2c-library
-@item -ff2c-library
-Specify that use of @code{libg2c} (or the original @code{libf2c})
-is required.
-This is the default for the current version of @code{g77}.
-
-Currently it is not
-valid to specify @samp{-fno-f2c-library}.
-This option is provided so users can specify it in shell
-scripts that build programs and libraries that require the
-@code{libf2c} library, even when being compiled by future
-versions of @code{g77} that might otherwise default to
-generating code for an incompatible library.
-
-@cindex -fno-underscoring option
-@cindex options, -fno-underscoring
-@item -fno-underscoring
-@cindex underscore
-@cindex symbol names, underscores
-@cindex transforming symbol names
-@cindex symbol names, transforming
-Do not transform names of entities specified in the Fortran
-source file by appending underscores to them.
-
-With @samp{-funderscoring} in effect, @code{g77} appends two underscores
-to names with underscores and one underscore to external names with
-no underscores. (@code{g77} also appends two underscores to internal
-names with underscores to avoid naming collisions with external names.
-The @samp{-fno-second-underscore} option disables appending of the
-second underscore in all cases.)
-
-This is done to ensure compatibility with code produced by many
-UNIX Fortran compilers, including @code{f2c}, which perform the
-same transformations.
-
-Use of @samp{-fno-underscoring} is not recommended unless you are
-experimenting with issues such as integration of (GNU) Fortran into
-existing system environments (vis-a-vis existing libraries, tools, and
-so on).
-
-For example, with @samp{-funderscoring}, and assuming other defaults like
-@samp{-fcase-lower} and that @samp{j()} and @samp{max_count()} are
-external functions while @samp{my_var} and @samp{lvar} are local variables,
-a statement like
-
-@smallexample
-I = J() + MAX_COUNT (MY_VAR, LVAR)
-@end smallexample
-
-@noindent
-is implemented as something akin to:
-
-@smallexample
-i = j_() + max_count__(&my_var__, &lvar);
-@end smallexample
-
-With @samp{-fno-underscoring}, the same statement is implemented as:
-
-@smallexample
-i = j() + max_count(&my_var, &lvar);
-@end smallexample
-
-Use of @samp{-fno-underscoring} allows direct specification of
-user-defined names while debugging and when interfacing @code{g77}-compiled
-code with other languages.
-
-Note that just because the names match does @emph{not} mean that the
-interface implemented by @code{g77} for an external name matches the
-interface implemented by some other language for that same name.
-That is, getting code produced by @code{g77} to link to code produced
-by some other compiler using this or any other method can be only a
-small part of the overall solution---getting the code generated by
-both compilers to agree on issues other than naming can require
-significant effort, and, unlike naming disagreements, linkers normally
-cannot detect disagreements in these other areas.
-
-Also, note that with @samp{-fno-underscoring}, the lack of appended
-underscores introduces the very real possibility that a user-defined
-external name will conflict with a name in a system library, which
-could make finding unresolved-reference bugs quite difficult in some
-cases---they might occur at program run time, and show up only as
-buggy behavior at run time.
-
-In future versions of @code{g77}, we hope to improve naming and linking
-issues so that debugging always involves using the names as they appear
-in the source, even if the names as seen by the linker are mangled to
-prevent accidental linking between procedures with incompatible
-interfaces.
-
-@cindex -fno-second-underscore option
-@cindex options, -fno-second-underscore
-@item -fno-second-underscore
-@cindex underscore
-@cindex symbol names, underscores
-@cindex transforming symbol names
-@cindex symbol names, transforming
-Do not append a second underscore to names of entities specified
-in the Fortran source file.
-
-This option has no effect if @samp{-fno-underscoring} is
-in effect.
-
-Otherwise, with this option, an external name such as @samp{MAX_COUNT}
-is implemented as a reference to the link-time external symbol
-@samp{max_count_}, instead of @samp{max_count__}.
-
-@cindex -fno-ident option
-@cindex options, -fno-ident
-@item -fno-ident
-Ignore the @samp{#ident} directive.
-
-@cindex -fzeros option
-@cindex options, -fzeros
-@item -fzeros
-Treat initial values of zero as if they were any other value.
-
-As of version 0.5.18, @code{g77} normally treats @code{DATA} and
-other statements that are used to specify initial values of zero
-for variables and arrays as if no values were actually specified,
-in the sense that no diagnostics regarding multiple initializations
-are produced.
-
-This is done to speed up compiling of programs that initialize
-large arrays to zeros.
-
-Use @samp{-fzeros} to revert to the simpler, slower behavior
-that can catch multiple initializations by keeping track of
-all initializations, zero or otherwise.
-
-@emph{Caution:} Future versions of @code{g77} might disregard this option
-(and its negative form, the default) or interpret it somewhat
-differently.
-The interpretation changes will affect only non-standard
-programs; standard-conforming programs should not be affected.
-
-@cindex -femulate-complex option
-@cindex options, -femulate-complex
-@item -femulate-complex
-Implement @code{COMPLEX} arithmetic via emulation,
-instead of using the facilities of
-the @code{gcc} back end that provide direct support of
-@code{complex} arithmetic.
-
-(@code{gcc} had some bugs in its back-end support
-for @code{complex} arithmetic, due primarily to the support not being
-completed as of version 2.8.1 and @code{egcs} 1.1.2.)
-
-Use @samp{-femulate-complex} if you suspect code-generation bugs,
-or experience compiler crashes,
-that might result from @code{g77} using the @code{COMPLEX} support
-in the @code{gcc} back end.
-If using that option fixes the bugs or crashes you are seeing,
-that indicates a likely @code{g77} bugs
-(though, all compiler crashes are considered bugs),
-so, please report it.
-(Note that the known bugs, now believed fixed, produced compiler crashes
-rather than causing the generation of incorrect code.)
-
-Use of this option should not affect how Fortran code compiled
-by @code{g77} works in terms of its interfaces to other code,
-e.g. that compiled by @code{f2c}.
-
-@emph{Caution:} Future versions of @code{g77} might ignore both forms
-of this option.
-
-@cindex -falias-check option
-@cindex options, -falias-check
-@cindex -fargument-alias option
-@cindex options, -fargument-alias
-@cindex -fargument-noalias option
-@cindex options, -fargument-noalias
-@cindex -fno-argument-noalias-global option
-@cindex options, -fno-argument-noalias-global
-@item -falias-check
-@item -fargument-alias
-@item -fargument-noalias
-@item -fno-argument-noalias-global
-@emph{Version info:}
-These options are not supported by
-versions of @code{g77} based on @code{gcc} version 2.8.
-
-These options specify to what degree aliasing
-(overlap)
-is permitted between
-arguments (passed as pointers) and @code{COMMON} (external, or
-public) storage.
-
-The default for Fortran code, as mandated by the FORTRAN 77 and
-Fortran 90 standards, is @samp{-fargument-noalias-global}.
-The default for code written in the C language family is
-@samp{-fargument-alias}.
-
-Note that, on some systems, compiling with @samp{-fforce-addr} in
-effect can produce more optimal code when the default aliasing
-options are in effect (and when optimization is enabled).
-
-@xref{Aliasing Assumed To Work}, for detailed information on the implications
-of compiling Fortran code that depends on the ability to alias dummy
-arguments.
-
-@cindex -fno-globals option
-@cindex options, -fno-globals
-@item -fno-globals
-@cindex global names, warning
-@cindex warnings, global names
-@cindex in-line code
-@cindex compilation, in-line
-Disable diagnostics about inter-procedural
-analysis problems, such as disagreements about the
-type of a function or a procedure's argument,
-that might cause a compiler crash when attempting
-to inline a reference to a procedure within a
-program unit.
-(The diagnostics themselves are still produced, but
-as warnings, unless @samp{-Wno-globals} is specified,
-in which case no relevant diagnostics are produced.)
-
-Further, this option disables such inlining, to
-avoid compiler crashes resulting from incorrect
-code that would otherwise be diagnosed.
-
-As such, this option might be quite useful when
-compiling existing, ``working'' code that happens
-to have a few bugs that do not generally show themselves,
-but which @code{g77} diagnoses.
-
-Use of this option therefore has the effect of
-instructing @code{g77} to behave more like it did
-up through version 0.5.19.1, when it paid little or
-no attention to disagreements between program units
-about a procedure's type and argument information,
-and when it performed no inlining of procedures
-(except statement functions).
-
-Without this option, @code{g77} defaults to performing
-the potentially inlining procedures as it started doing
-in version 0.5.20, but as of version 0.5.21, it also
-diagnoses disagreements that might cause such inlining
-to crash the compiler as (fatal) errors,
-and warns about similar disagreements
-that are currently believed to not
-likely to result in the compiler later crashing
-or producing incorrect code.
-
-@cindex -fflatten-arrays option
-@item -fflatten-arrays
-@cindex array performance
-@cindex arrays, flattening
-Use back end's C-like constructs
-(pointer plus offset)
-instead of its @code{ARRAY_REF} construct
-to handle all array references.
-
-@emph{Note:} This option is not supported.
-It is intended for use only by @code{g77} developers,
-to evaluate code-generation issues.
-It might be removed at any time.
-
-@cindex -fbounds-check option
-@cindex -ffortran-bounds-check option
-@item -fbounds-check
-@itemx -ffortran-bounds-check
-@cindex bounds checking
-@cindex range checking
-@cindex array bounds checking
-@cindex subscript checking
-@cindex substring checking
-@cindex checking subscripts
-@cindex checking substrings
-Enable generation of run-time checks for array subscripts
-and substring start and end points
-against the (locally) declared minimum and maximum values.
-
-The current implementation uses the @code{libf2c}
-library routine @code{s_rnge} to print the diagnostic.
-
-However, whereas @code{f2c} generates a single check per
-reference for a multi-dimensional array, of the computed
-offset against the valid offset range (0 through the size of the array),
-@code{g77} generates a single check per @emph{subscript} expression.
-This catches some cases of potential bugs that @code{f2c} does not,
-such as references to below the beginning of an assumed-size array.
-
-@code{g77} also generates checks for @code{CHARACTER} substring references,
-something @code{f2c} currently does not do.
-
-Use the new @samp{-ffortran-bounds-check} option
-to specify bounds-checking for only the Fortran code you are compiling,
-not necessarily for code written in other languages.
-
-@emph{Note:} To provide more detailed information on the offending subscript,
-@code{g77} provides the @code{libg2c} run-time library routine @code{s_rnge}
-with somewhat differently-formatted information.
-Here's a sample diagnostic:
-
-@smallexample
-Subscript out of range on file line 4, procedure rnge.f/bf.
-Attempt to access the -6-th element of variable b[subscript-2-of-2].
-Aborted
-@end smallexample
-
-The above message indicates that the offending source line is
-line 4 of the file @file{rnge.f},
-within the program unit (or statement function) named @samp{bf}.
-The offended array is named @samp{b}.
-The offended array dimension is the second for a two-dimensional array,
-and the offending, computed subscript expression was @samp{-6}.
-
-For a @code{CHARACTER} substring reference, the second line has
-this appearance:
-
-@smallexample
-Attempt to access the 11-th element of variable a[start-substring].
-@end smallexample
-
-This indicates that the offended @code{CHARACTER} variable or array
-is named @samp{a},
-the offended substring position is the starting (leftmost) position,
-and the offending substring expression is @samp{11}.
-
-(Though the verbage of @code{s_rnge} is not ideal
-for the purpose of the @code{g77} compiler,
-the above information should provide adequate diagnostic abilities
-to it users.)
-@end table
-
-@xref{Code Gen Options,,Options for Code Generation Conventions,
-gcc,Using and Porting GNU CC}, for information on more options
-offered by the GBE
-shared by @code{g77}, @code{gcc}, and other GNU compilers.
-
-Some of these do @emph{not} work when compiling programs written in Fortran:
-
-@table @code
-@cindex -fpcc-struct-return option
-@cindex options, -fpcc-struct-return
-@item -fpcc-struct-return
-@cindex -freg-struct-return option
-@cindex options, -freg-struct-return
-@item -freg-struct-return
-You should not use these except strictly the same way as you
-used them to build the version of @code{libg2c} with which
-you will be linking all code compiled by @code{g77} with the
-same option.
-
-@cindex -fshort-double option
-@cindex options, -fshort-double
-@item -fshort-double
-This probably either has no effect on Fortran programs, or
-makes them act loopy.
-
-@cindex -fno-common option
-@cindex options, -fno-common
-@item -fno-common
-Do not use this when compiling Fortran programs,
-or there will be Trouble.
-
-@cindex -fpack-struct option
-@cindex options, -fpack-struct
-@item -fpack-struct
-This probably will break any calls to the @code{libg2c} library,
-at the very least, even if it is built with the same option.
-@end table
-
-@node Environment Variables
-@section Environment Variables Affecting GNU Fortran
-@cindex environment variables
-
-GNU Fortran currently does not make use of any environment
-variables to control its operation above and beyond those
-that affect the operation of @code{gcc}.
-
-@xref{Environment Variables,,Environment Variables Affecting GNU CC,
-gcc,Using and Porting GNU CC}, for information on environment
-variables.
+@include invoke.texi
@include news.texi
--- /dev/null
+@node Option Summary
+@section Option Summary
+
+Here is a summary of all the options specific to GNU Fortran, grouped
+by type. Explanations are in the following sections.
+
+@table @emph
+@item Overall Options
+@xref{Overall Options,,Options Controlling the Kind of Output}.
+@smallexample
+-fversion -fset-g77-defaults -fno-silent
+@end smallexample
+
+@item Shorthand Options
+@xref{Shorthand Options}.
+@smallexample
+-ff66 -fno-f66 -ff77 -fno-f77 -fno-ugly
+@end smallexample
+
+@item Fortran Language Options
+@xref{Fortran Dialect Options,,Options Controlling Fortran Dialect}.
+@smallexample
+-ffree-form -fno-fixed-form -ff90
+-fvxt -fdollar-ok -fno-backslash
+-fno-ugly-args -fno-ugly-assign -fno-ugly-assumed
+-fugly-comma -fugly-complex -fugly-init -fugly-logint
+-fonetrip -ftypeless-boz
+-fintrin-case-initcap -fintrin-case-upper
+-fintrin-case-lower -fintrin-case-any
+-fmatch-case-initcap -fmatch-case-upper
+-fmatch-case-lower -fmatch-case-any
+-fsource-case-upper -fsource-case-lower
+-fsource-case-preserve
+-fsymbol-case-initcap -fsymbol-case-upper
+-fsymbol-case-lower -fsymbol-case-any
+-fcase-strict-upper -fcase-strict-lower
+-fcase-initcap -fcase-upper -fcase-lower -fcase-preserve
+-ff2c-intrinsics-delete -ff2c-intrinsics-hide
+-ff2c-intrinsics-disable -ff2c-intrinsics-enable
+-fbadu77-intrinsics-delete -fbadu77-intrinsics-hide
+-fbadu77-intrinsics-disable -fbadu77-intrinsics-enable
+-ff90-intrinsics-delete -ff90-intrinsics-hide
+-ff90-intrinsics-disable -ff90-intrinsics-enable
+-fgnu-intrinsics-delete -fgnu-intrinsics-hide
+-fgnu-intrinsics-disable -fgnu-intrinsics-enable
+-fmil-intrinsics-delete -fmil-intrinsics-hide
+-fmil-intrinsics-disable -fmil-intrinsics-enable
+-funix-intrinsics-delete -funix-intrinsics-hide
+-funix-intrinsics-disable -funix-intrinsics-enable
+-fvxt-intrinsics-delete -fvxt-intrinsics-hide
+-fvxt-intrinsics-disable -fvxt-intrinsics-enable
+-ffixed-line-length-@var{n} -ffixed-line-length-none
+@end smallexample
+
+@item Warning Options
+@xref{Warning Options,,Options to Request or Suppress Warnings}.
+@smallexample
+-fsyntax-only -pedantic -pedantic-errors -fpedantic
+-w -Wno-globals -Wimplicit -Wunused -Wuninitialized
+-Wall -Wsurprising
+-Werror -W
+@end smallexample
+
+@item Debugging Options
+@xref{Debugging Options,,Options for Debugging Your Program or GCC}.
+@smallexample
+-g
+@end smallexample
+
+@item Optimization Options
+@xref{Optimize Options,,Options that Control Optimization}.
+@smallexample
+-malign-double
+-ffloat-store -fforce-mem -fforce-addr -fno-inline
+-ffast-math -fstrength-reduce -frerun-cse-after-loop
+-funsafe-math-optimizations -fno-trapping-math
+-fexpensive-optimizations -fdelayed-branch
+-fschedule-insns -fschedule-insn2 -fcaller-saves
+-funroll-loops -funroll-all-loops
+-fno-move-all-movables -fno-reduce-all-givs
+-fno-rerun-loop-opt
+@end smallexample
+
+@item Directory Options
+@xref{Directory Options,,Options for Directory Search}.
+@smallexample
+-I@var{dir} -I-
+@end smallexample
+
+@item Code Generation Options
+@xref{Code Gen Options,,Options for Code Generation Conventions}.
+@smallexample
+-fno-automatic -finit-local-zero -fno-f2c
+-ff2c-library -fno-underscoring -fno-ident
+-fpcc-struct-return -freg-struct-return
+-fshort-double -fno-common -fpack-struct
+-fzeros -fno-second-underscore
+-femulate-complex
+-falias-check -fargument-alias
+-fargument-noalias -fno-argument-noalias-global
+-fno-globals -fflatten-arrays
+-fbounds-check -ffortran-bounds-check
+@end smallexample
+@end table
+
+@menu
+* Overall Options:: Controlling the kind of output:
+ an executable, object files, assembler files,
+ or preprocessed source.
+* Shorthand Options:: Options that are shorthand for other options.
+* Fortran Dialect Options:: Controlling the variant of Fortran language
+ compiled.
+* Warning Options:: How picky should the compiler be?
+* Debugging Options:: Symbol tables, measurements, and debugging dumps.
+* Optimize Options:: How much optimization?
+* Preprocessor Options:: Controlling header files and macro definitions.
+ Also, getting dependency information for Make.
+* Directory Options:: Where to find header files and libraries.
+ Where to find the compiler executable files.
+* Code Gen Options:: Specifying conventions for function calls, data layout
+ and register usage.
+@end menu
+
+@node Overall Options
+@section Options Controlling the Kind of Output
+@cindex overall options
+@cindex options, overall
+
+Compilation can involve as many as four stages: preprocessing, code
+generation (often what is really meant by the term ``compilation''),
+assembly, and linking, always in that order. The first three
+stages apply to an individual source file, and end by producing an
+object file; linking combines all the object files (those newly
+compiled, and those specified as input) into an executable file.
+
+@cindex file name suffix
+@cindex suffixes, file name
+@cindex file name extension
+@cindex extensions, file name
+@cindex file type
+@cindex types, file
+For any given input file, the file name suffix determines what kind of
+program is contained in the file---that is, the language in which the
+program is written is generally indicated by the suffix.
+Suffixes specific to GNU Fortran are listed below.
+@xref{Overall Options,,gcc,Using and Porting GNU CC}, for
+information on suffixes recognized by GNU CC.
+
+@table @code
+@cindex .f filename suffix
+@cindex .for filename suffix
+@cindex .FOR filename suffix
+@item @var{file}.f
+@item @var{file}.for
+@item @var{file}.FOR
+Fortran source code that should not be preprocessed.
+
+Such source code cannot contain any preprocessor directives, such
+as @code{#include}, @code{#define}, @code{#if}, and so on.
+
+You can force @samp{.f} files to be preprocessed by @code{cpp} by using
+@samp{-x f77-cpp-input}.
+@xref{LEX}.
+
+@cindex preprocessor
+@cindex C preprocessor
+@cindex cpp preprocessor
+@cindex Fortran preprocessor
+@cindex cpp program
+@cindex programs, cpp
+@cindex .F filename suffix
+@cindex .fpp filename suffix
+@cindex .FPP filename suffix
+@item @var{file}.F
+@item @var{file}.fpp
+@item @var{file}.FPP
+Fortran source code that must be preprocessed (by the C preprocessor
+@code{cpp}, which is part of GNU CC).
+
+Note that preprocessing is not extended to the contents of
+files included by the @code{INCLUDE} directive---the @code{#include}
+preprocessor directive must be used instead.
+
+@cindex Ratfor preprocessor
+@cindex programs, @code{ratfor}
+@cindex @samp{.r} filename suffix
+@cindex @code{ratfor}
+@item @var{file}.r
+Ratfor source code, which must be preprocessed by the @code{ratfor}
+command, which is available separately (as it is not yet part of the GNU
+Fortran distribution).
+One version in Fortran, adapted for use with @code{g77}, is at
+@uref{ftp://members.aol.com/n8tm/rat7.uue} (of uncertain copyright
+status). Another, public domain version in C is at
+@uref{http://sepwww.stanford.edu/sep/prof/ratfor.shar.2}.
+@end table
+
+UNIX users typically use the @file{@var{file}.f} and @file{@var{file}.F}
+nomenclature.
+Users of other operating systems, especially those that cannot
+distinguish upper-case
+letters from lower-case letters in their file names, typically use
+the @file{@var{file}.for} and @file{@var{file}.fpp} nomenclature.
+
+@cindex #define
+@cindex #include
+@cindex #if
+Use of the preprocessor @code{cpp} allows use of C-like
+constructs such as @code{#define} and @code{#include}, but can
+lead to unexpected, even mistaken, results due to Fortran's source file
+format.
+It is recommended that use of the C preprocessor
+be limited to @code{#include} and, in
+conjunction with @code{#define}, only @code{#if} and related directives,
+thus avoiding in-line macro expansion entirely.
+This recommendation applies especially
+when using the traditional fixed source form.
+With free source form,
+fewer unexpected transformations are likely to happen, but use of
+constructs such as Hollerith and character constants can nevertheless
+present problems, especially when these are continued across multiple
+source lines.
+These problems result, primarily, from differences between the way
+such constants are interpreted by the C preprocessor and by a Fortran
+compiler.
+
+Another example of a problem that results from using the C preprocessor
+is that a Fortran comment line that happens to contain any
+characters ``interesting'' to the C preprocessor,
+such as a backslash at the end of the line,
+is not recognized by the preprocessor as a comment line,
+so instead of being passed through ``raw'',
+the line is edited according to the rules for the preprocessor.
+For example, the backslash at the end of the line is removed,
+along with the subsequent newline, resulting in the next
+line being effectively commented out---unfortunate if that
+line is a non-comment line of important code!
+
+@emph{Note:} The @samp{-traditional} and @samp{-undef} flags are supplied
+to @code{cpp} by default, to help avoid unpleasant surprises.
+@xref{Preprocessor Options,,Options Controlling the Preprocessor,
+gcc,Using and Porting GNU CC}.
+This means that ANSI C preprocessor features (such as the @samp{#}
+operator) aren't available, and only variables in the C reserved
+namespace (generally, names with a leading underscore) are liable to
+substitution by C predefines.
+Thus, if you want to do system-specific
+tests, use, for example, @samp{#ifdef __linux__} rather than @samp{#ifdef linux}.
+Use the @samp{-v} option to see exactly how the preprocessor is invoked.
+
+@cindex /*
+Unfortunately, the @samp{-traditional} flag will not avoid an error from
+anything that @code{cpp} sees as an unterminated C comment, such as:
+@smallexample
+C Some Fortran compilers accept /* as starting
+C an inline comment.
+@end smallexample
+@xref{Trailing Comment}.
+
+The following options that affect overall processing are recognized
+by the @code{g77} and @code{gcc} commands in a GNU Fortran installation:
+
+@table @code
+@cindex -fversion option
+@cindex options, -fversion
+@cindex printing version information
+@cindex version information, printing
+@cindex consistency checks
+@cindex internal consistency checks
+@cindex checks, of internal consistency
+@item -fversion
+Ensure that the @code{g77}-specific version of the compiler phase is reported,
+if run,
+and, starting in @code{egcs} version 1.1,
+that internal consistency checks in the @file{f771} program are run.
+
+This option is supplied automatically when @samp{-v} or @samp{--verbose}
+is specified as a command-line option for @code{g77} or @code{gcc}
+and when the resulting commands compile Fortran source files.
+
+@cindex -fset-g77-defaults option
+@cindex options, -fset-g77-defaults
+@item -fset-g77-defaults
+@emph{Version info:}
+This option was obsolete as of @code{egcs}
+version 1.1.
+The effect is instead achieved
+by the @code{lang_init_options} routine
+in @file{gcc/gcc/f/com.c}.
+
+@cindex consistency checks
+@cindex internal consistency checks
+@cindex checks, of internal consistency
+Set up whatever @code{gcc} options are to apply to Fortran
+compilations, and avoid running internal consistency checks
+that might take some time.
+
+This option is supplied automatically when compiling Fortran code
+via the @code{g77} or @code{gcc} command.
+The description of this option is provided so that users seeing
+it in the output of, say, @samp{g77 -v} understand why it is
+there.
+
+@cindex modifying g77
+@cindex code, modifying
+Also, developers who run @code{f771} directly might want to specify it
+by hand to get the same defaults as they would running @code{f771}
+via @code{g77} or @code{gcc}.
+However, such developers should, after linking a new @code{f771}
+executable, invoke it without this option once,
+e.g. via @kbd{./f771 -quiet < /dev/null},
+to ensure that they have not introduced any
+internal inconsistencies (such as in the table of
+intrinsics) before proceeding---@code{g77} will crash
+with a diagnostic if it detects an inconsistency.
+
+@cindex -fno-silent option
+@cindex options, -fno-silent
+@cindex f2c compatibility
+@cindex compatibility, f2c
+@cindex status, compilation
+@cindex compilation, status
+@cindex reporting compilation status
+@cindex printing compilation status
+@item -fno-silent
+Print (to @code{stderr}) the names of the program units as
+they are compiled, in a form similar to that used by popular
+UNIX @code{f77} implementations and @code{f2c}.
+@end table
+
+@xref{Overall Options,,Options Controlling the Kind of Output,
+gcc,Using and Porting GNU CC}, for information
+on more options that control the overall operation of the @code{gcc} command
+(and, by extension, the @code{g77} command).
+
+@node Shorthand Options
+@section Shorthand Options
+@cindex shorthand options
+@cindex options, shorthand
+@cindex macro options
+@cindex options, macro
+
+The following options serve as ``shorthand''
+for other options accepted by the compiler:
+
+@table @code
+@cindex -fugly option
+@cindex options, -fugly
+@item -fugly
+@cindex ugly features
+@cindex features, ugly
+@emph{Note:} This option is no longer supported.
+The information, below, is provided to aid
+in the conversion of old scripts.
+
+Specify that certain ``ugly'' constructs are to be quietly accepted.
+Same as:
+
+@smallexample
+-fugly-args -fugly-assign -fugly-assumed
+-fugly-comma -fugly-complex -fugly-init
+-fugly-logint
+@end smallexample
+
+These constructs are considered inappropriate to use in new
+or well-maintained portable Fortran code, but widely used
+in old code.
+@xref{Distensions}, for more information.
+
+@cindex -fno-ugly option
+@cindex options, -fno-ugly
+@item -fno-ugly
+@cindex ugly features
+@cindex features, ugly
+Specify that all ``ugly'' constructs are to be noisily rejected.
+Same as:
+
+@smallexample
+-fno-ugly-args -fno-ugly-assign -fno-ugly-assumed
+-fno-ugly-comma -fno-ugly-complex -fno-ugly-init
+-fno-ugly-logint
+@end smallexample
+
+@xref{Distensions}, for more information.
+
+@cindex -ff66 option
+@cindex options, -ff66
+@item -ff66
+@cindex FORTRAN 66
+@cindex compatibility, FORTRAN 66
+Specify that the program is written in idiomatic FORTRAN 66.
+Same as @samp{-fonetrip -fugly-assumed}.
+
+The @samp{-fno-f66} option is the inverse of @samp{-ff66}.
+As such, it is the same as @samp{-fno-onetrip -fno-ugly-assumed}.
+
+The meaning of this option is likely to be refined as future
+versions of @code{g77} provide more compatibility with other
+existing and obsolete Fortran implementations.
+
+@cindex -ff77 option
+@cindex options, -ff77
+@item -ff77
+@cindex UNIX f77
+@cindex f2c compatibility
+@cindex compatibility, f2c
+@cindex f77 compatibility
+@cindex compatibility, f77
+Specify that the program is written in idiomatic UNIX FORTRAN 77
+and/or the dialect accepted by the @code{f2c} product.
+Same as @samp{-fbackslash -fno-typeless-boz}.
+
+The meaning of this option is likely to be refined as future
+versions of @code{g77} provide more compatibility with other
+existing and obsolete Fortran implementations.
+
+@cindex -fno-f77 option
+@cindex options, -fno-f77
+@item -fno-f77
+@cindex UNIX f77
+The @samp{-fno-f77} option is @emph{not} the inverse
+of @samp{-ff77}.
+It specifies that the program is not written in idiomatic UNIX
+FORTRAN 77 or @code{f2c}, but in a more widely portable dialect.
+@samp{-fno-f77} is the same as @samp{-fno-backslash}.
+
+The meaning of this option is likely to be refined as future
+versions of @code{g77} provide more compatibility with other
+existing and obsolete Fortran implementations.
+@end table
+
+@node Fortran Dialect Options
+@section Options Controlling Fortran Dialect
+@cindex dialect options
+@cindex language, dialect options
+@cindex options, dialect
+
+The following options control the dialect of Fortran
+that the compiler accepts:
+
+@table @code
+@cindex -ffree-form option
+@cindex options, -ffree-form
+@cindex -fno-fixed-form option
+@cindex options, -fno-fixed-form
+@cindex source file format
+@cindex free form
+@cindex fixed form
+@cindex Fortran 90, features
+@item -ffree-form
+@item -fno-fixed-form
+Specify that the source file is written in free form
+(introduced in Fortran 90) instead of the more-traditional fixed form.
+
+@cindex -ff90 option
+@cindex options, -ff90
+@cindex Fortran 90, features
+@item -ff90
+Allow certain Fortran-90 constructs.
+
+This option controls whether certain
+Fortran 90 constructs are recognized.
+(Other Fortran 90 constructs
+might or might not be recognized depending on other options such as
+@samp{-fvxt}, @samp{-ff90-intrinsics-enable}, and the
+current level of support for Fortran 90.)
+
+@xref{Fortran 90}, for more information.
+
+@cindex -fvxt option
+@cindex options, -fvxt
+@item -fvxt
+@cindex Fortran 90, features
+@cindex VXT extensions
+Specify the treatment of certain constructs that have different
+meanings depending on whether the code is written in
+GNU Fortran (based on FORTRAN 77 and akin to Fortran 90)
+or VXT Fortran (more like VAX FORTRAN).
+
+The default is @samp{-fno-vxt}.
+@samp{-fvxt} specifies that the VXT Fortran interpretations
+for those constructs are to be chosen.
+
+@xref{VXT Fortran}, for more information.
+
+@cindex -fdollar-ok option
+@cindex options, -fdollar-ok
+@item -fdollar-ok
+@cindex dollar sign
+@cindex symbol names
+@cindex character set
+Allow @samp{$} as a valid character in a symbol name.
+
+@cindex -fno-backslash option
+@cindex options, -fno-backslash
+@item -fno-backslash
+@cindex backslash
+@cindex character constants
+@cindex Hollerith constants
+Specify that @samp{\} is not to be specially interpreted in character
+and Hollerith constants a la C and many UNIX Fortran compilers.
+
+For example, with @samp{-fbackslash} in effect, @samp{A\nB} specifies
+three characters, with the second one being newline.
+With @samp{-fno-backslash}, it specifies four characters,
+@samp{A}, @samp{\}, @samp{n}, and @samp{B}.
+
+Note that @code{g77} implements a fairly general form of backslash
+processing that is incompatible with the narrower forms supported
+by some other compilers.
+For example, @samp{'A\003B'} is a three-character string in @code{g77},
+whereas other compilers that support backslash might not support
+the three-octal-digit form, and thus treat that string as longer
+than three characters.
+
+@xref{Backslash in Constants}, for
+information on why @samp{-fbackslash} is the default
+instead of @samp{-fno-backslash}.
+
+@cindex -fno-ugly-args option
+@cindex options, -fno-ugly-args
+@item -fno-ugly-args
+Disallow passing Hollerith and typeless constants as actual
+arguments (for example, @samp{CALL FOO(4HABCD)}).
+
+@xref{Ugly Implicit Argument Conversion}, for more information.
+
+@cindex -fugly-assign option
+@cindex options, -fugly-assign
+@item -fugly-assign
+Use the same storage for a given variable regardless of
+whether it is used to hold an assigned-statement label
+(as in @samp{ASSIGN 10 TO I}) or used to hold numeric data
+(as in @samp{I = 3}).
+
+@xref{Ugly Assigned Labels}, for more information.
+
+@cindex -fugly-assumed option
+@cindex options, -fugly-assumed
+@item -fugly-assumed
+Assume any dummy array with a final dimension specified as @samp{1}
+is really an assumed-size array, as if @samp{*} had been specified
+for the final dimension instead of @samp{1}.
+
+For example, @samp{DIMENSION X(1)} is treated as if it
+had read @samp{DIMENSION X(*)}.
+
+@xref{Ugly Assumed-Size Arrays}, for more information.
+
+@cindex -fugly-comma option
+@cindex options, -fugly-comma
+@item -fugly-comma
+In an external-procedure invocation,
+treat a trailing comma in the argument list
+as specification of a trailing null argument,
+and treat an empty argument list
+as specification of a single null argument.
+
+For example, @samp{CALL FOO(,)} is treated as
+@samp{CALL FOO(%VAL(0), %VAL(0))}.
+That is, @emph{two} null arguments are specified
+by the procedure call when @samp{-fugly-comma} is in force.
+And @samp{F = FUNC()} is treated as @samp{F = FUNC(%VAL(0))}.
+
+The default behavior, @samp{-fno-ugly-comma}, is to ignore
+a single trailing comma in an argument list.
+So, by default, @samp{CALL FOO(X,)} is treated
+exactly the same as @samp{CALL FOO(X)}.
+
+@xref{Ugly Null Arguments}, for more information.
+
+@cindex -fugly-complex option
+@cindex options, -fugly-complex
+@item -fugly-complex
+Do not complain about @samp{REAL(@var{expr})} or
+@samp{AIMAG(@var{expr})} when @var{expr} is a @code{COMPLEX}
+type other than @code{COMPLEX(KIND=1)}---usually
+this is used to permit @code{COMPLEX(KIND=2)}
+(@code{DOUBLE COMPLEX}) operands.
+
+The @samp{-ff90} option controls the interpretation
+of this construct.
+
+@xref{Ugly Complex Part Extraction}, for more information.
+
+@cindex -fno-ugly-init option
+@cindex options, -fno-ugly-init
+@item -fno-ugly-init
+Disallow use of Hollerith and typeless constants as initial
+values (in @code{PARAMETER} and @code{DATA} statements), and
+use of character constants to
+initialize numeric types and vice versa.
+
+For example, @samp{DATA I/'F'/, CHRVAR/65/, J/4HABCD/} is disallowed by
+@samp{-fno-ugly-init}.
+
+@xref{Ugly Conversion of Initializers}, for more information.
+
+@cindex -fugly-logint option
+@cindex options, -fugly-logint
+@item -fugly-logint
+Treat @code{INTEGER} and @code{LOGICAL} variables and
+expressions as potential stand-ins for each other.
+
+For example, automatic conversion between @code{INTEGER} and
+@code{LOGICAL} is enabled, for many contexts, via this option.
+
+@xref{Ugly Integer Conversions}, for more information.
+
+@cindex -fonetrip option
+@cindex options, -fonetrip
+@item -fonetrip
+@cindex FORTRAN 66
+@cindex @code{DO} loops, one-trip
+@cindex one-trip @code{DO} loops
+@cindex @code{DO} loops, zero-trip
+@cindex zero-trip @code{DO} loops
+@cindex compatibility, FORTRAN 66
+Executable iterative @code{DO} loops are to be executed at
+least once each time they are reached.
+
+ANSI FORTRAN 77 and more recent versions of the Fortran standard
+specify that the body of an iterative @code{DO} loop is not executed
+if the number of iterations calculated from the parameters of the
+loop is less than 1.
+(For example, @samp{DO 10 I = 1, 0}.)
+Such a loop is called a @dfn{zero-trip loop}.
+
+Prior to ANSI FORTRAN 77, many compilers implemented @code{DO} loops
+such that the body of a loop would be executed at least once, even
+if the iteration count was zero.
+Fortran code written assuming this behavior is said to require
+@dfn{one-trip loops}.
+For example, some code written to the FORTRAN 66 standard
+expects this behavior from its @code{DO} loops, although that
+standard did not specify this behavior.
+
+The @samp{-fonetrip} option specifies that the source file(s) being
+compiled require one-trip loops.
+
+This option affects only those loops specified by the (iterative) @code{DO}
+statement and by implied-@code{DO} lists in I/O statements.
+Loops specified by implied-@code{DO} lists in @code{DATA} and
+specification (non-executable) statements are not affected.
+
+@cindex -ftypeless-boz option
+@cindex options, -ftypeless-boz
+@cindex prefix-radix constants
+@cindex constants, prefix-radix
+@cindex constants, types
+@cindex types, constants
+@item -ftypeless-boz
+Specifies that prefix-radix non-decimal constants, such as
+@samp{Z'ABCD'}, are typeless instead of @code{INTEGER(KIND=1)}.
+
+You can test for yourself whether a particular compiler treats
+the prefix form as @code{INTEGER(KIND=1)} or typeless by running the
+following program:
+
+@smallexample
+EQUIVALENCE (I, R)
+R = Z'ABCD1234'
+J = Z'ABCD1234'
+IF (J .EQ. I) PRINT *, 'Prefix form is TYPELESS'
+IF (J .NE. I) PRINT *, 'Prefix form is INTEGER'
+END
+@end smallexample
+
+Reports indicate that many compilers process this form as
+@code{INTEGER(KIND=1)}, though a few as typeless, and at least one
+based on a command-line option specifying some kind of
+compatibility.
+
+@cindex -fintrin-case-initcap option
+@cindex options, -fintrin-case-initcap
+@item -fintrin-case-initcap
+@cindex -fintrin-case-upper option
+@cindex options, -fintrin-case-upper
+@item -fintrin-case-upper
+@cindex -fintrin-case-lower option
+@cindex options, -fintrin-case-lower
+@item -fintrin-case-lower
+@cindex -fintrin-case-any option
+@cindex options, -fintrin-case-any
+@item -fintrin-case-any
+Specify expected case for intrinsic names.
+@samp{-fintrin-case-lower} is the default.
+
+@cindex -fmatch-case-initcap option
+@cindex options, -fmatch-case-initcap
+@item -fmatch-case-initcap
+@cindex -fmatch-case-upper option
+@cindex options, -fmatch-case-upper
+@item -fmatch-case-upper
+@cindex -fmatch-case-lower option
+@cindex options, -fmatch-case-lower
+@item -fmatch-case-lower
+@cindex -fmatch-case-any option
+@cindex options, -fmatch-case-any
+@item -fmatch-case-any
+Specify expected case for keywords.
+@samp{-fmatch-case-lower} is the default.
+
+@cindex -fsource-case-upper option
+@cindex options, -fsource-case-upper
+@item -fsource-case-upper
+@cindex -fsource-case-lower option
+@cindex options, -fsource-case-lower
+@item -fsource-case-lower
+@cindex -fsource-case-preserve option
+@cindex options, -fsource-case-preserve
+@item -fsource-case-preserve
+Specify whether source text other than character and Hollerith constants
+is to be translated to uppercase, to lowercase, or preserved as is.
+@samp{-fsource-case-lower} is the default.
+
+@cindex -fsymbol-case-initcap option
+@cindex options, -fsymbol-case-initcap
+@item -fsymbol-case-initcap
+@cindex -fsymbol-case-upper option
+@cindex options, -fsymbol-case-upper
+@item -fsymbol-case-upper
+@cindex -fsymbol-case-lower option
+@cindex options, -fsymbol-case-lower
+@item -fsymbol-case-lower
+@cindex -fsymbol-case-any option
+@cindex options, -fsymbol-case-any
+@item -fsymbol-case-any
+Specify valid cases for user-defined symbol names.
+@samp{-fsymbol-case-any} is the default.
+
+@cindex -fcase-strict-upper option
+@cindex options, -fcase-strict-upper
+@item -fcase-strict-upper
+Same as @samp{-fintrin-case-upper -fmatch-case-upper -fsource-case-preserve
+-fsymbol-case-upper}.
+(Requires all pertinent source to be in uppercase.)
+
+@cindex -fcase-strict-lower option
+@cindex options, -fcase-strict-lower
+@item -fcase-strict-lower
+Same as @samp{-fintrin-case-lower -fmatch-case-lower -fsource-case-preserve
+-fsymbol-case-lower}.
+(Requires all pertinent source to be in lowercase.)
+
+@cindex -fcase-initcap option
+@cindex options, -fcase-initcap
+@item -fcase-initcap
+Same as @samp{-fintrin-case-initcap -fmatch-case-initcap -fsource-case-preserve
+-fsymbol-case-initcap}.
+(Requires all pertinent source to be in initial capitals,
+as in @samp{Print *,SqRt(Value)}.)
+
+@cindex -fcase-upper option
+@cindex options, -fcase-upper
+@item -fcase-upper
+Same as @samp{-fintrin-case-any -fmatch-case-any -fsource-case-upper
+-fsymbol-case-any}.
+(Maps all pertinent source to uppercase.)
+
+@cindex -fcase-lower option
+@cindex options, -fcase-lower
+@item -fcase-lower
+Same as @samp{-fintrin-case-any -fmatch-case-any -fsource-case-lower
+-fsymbol-case-any}.
+(Maps all pertinent source to lowercase.)
+
+@cindex -fcase-preserve option
+@cindex options, -fcase-preserve
+@item -fcase-preserve
+Same as @samp{-fintrin-case-any -fmatch-case-any -fsource-case-preserve
+-fsymbol-case-any}.
+(Preserves all case in user-defined symbols,
+while allowing any-case matching of intrinsics and keywords.
+For example, @samp{call Foo(i,I)} would pass two @emph{different}
+variables named @samp{i} and @samp{I} to a procedure named @samp{Foo}.)
+
+@cindex -fbadu77-intrinsics-delete option
+@cindex options, -fbadu77-intrinsics-delete
+@item -fbadu77-intrinsics-delete
+@cindex -fbadu77-intrinsics-hide option
+@cindex options, -fbadu77-intrinsics-hide
+@item -fbadu77-intrinsics-hide
+@cindex -fbadu77-intrinsics-disable option
+@cindex options, -fbadu77-intrinsics-disable
+@item -fbadu77-intrinsics-disable
+@cindex -fbadu77-intrinsics-enable option
+@cindex options, -fbadu77-intrinsics-enable
+@item -fbadu77-intrinsics-enable
+@cindex @code{badu77} intrinsics
+@cindex intrinsics, @code{badu77}
+Specify status of UNIX intrinsics having inappropriate forms.
+@samp{-fbadu77-intrinsics-enable} is the default.
+@xref{Intrinsic Groups}.
+
+@cindex -ff2c-intrinsics-delete option
+@cindex options, -ff2c-intrinsics-delete
+@item -ff2c-intrinsics-delete
+@cindex -ff2c-intrinsics-hide option
+@cindex options, -ff2c-intrinsics-hide
+@item -ff2c-intrinsics-hide
+@cindex -ff2c-intrinsics-disable option
+@cindex options, -ff2c-intrinsics-disable
+@item -ff2c-intrinsics-disable
+@cindex -ff2c-intrinsics-enable option
+@cindex options, -ff2c-intrinsics-enable
+@item -ff2c-intrinsics-enable
+@cindex @code{f2c} intrinsics
+@cindex intrinsics, @code{f2c}
+Specify status of f2c-specific intrinsics.
+@samp{-ff2c-intrinsics-enable} is the default.
+@xref{Intrinsic Groups}.
+
+@cindex -ff90-intrinsics-delete option
+@cindex options, -ff90-intrinsics-delete
+@item -ff90-intrinsics-delete
+@cindex -ff90-intrinsics-hide option
+@cindex options, -ff90-intrinsics-hide
+@item -ff90-intrinsics-hide
+@cindex -ff90-intrinsics-disable option
+@cindex options, -ff90-intrinsics-disable
+@item -ff90-intrinsics-disable
+@cindex -ff90-intrinsics-enable option
+@cindex options, -ff90-intrinsics-enable
+@item -ff90-intrinsics-enable
+@cindex Fortran 90, intrinsics
+@cindex intrinsics, Fortran 90
+Specify status of F90-specific intrinsics.
+@samp{-ff90-intrinsics-enable} is the default.
+@xref{Intrinsic Groups}.
+
+@cindex -fgnu-intrinsics-delete option
+@cindex options, -fgnu-intrinsics-delete
+@item -fgnu-intrinsics-delete
+@cindex -fgnu-intrinsics-hide option
+@cindex options, -fgnu-intrinsics-hide
+@item -fgnu-intrinsics-hide
+@cindex -fgnu-intrinsics-disable option
+@cindex options, -fgnu-intrinsics-disable
+@item -fgnu-intrinsics-disable
+@cindex -fgnu-intrinsics-enable option
+@cindex options, -fgnu-intrinsics-enable
+@item -fgnu-intrinsics-enable
+@cindex Digital Fortran features
+@cindex @code{COMPLEX} intrinsics
+@cindex intrinsics, @code{COMPLEX}
+Specify status of Digital's COMPLEX-related intrinsics.
+@samp{-fgnu-intrinsics-enable} is the default.
+@xref{Intrinsic Groups}.
+
+@cindex -fmil-intrinsics-delete option
+@cindex options, -fmil-intrinsics-delete
+@item -fmil-intrinsics-delete
+@cindex -fmil-intrinsics-hide option
+@cindex options, -fmil-intrinsics-hide
+@item -fmil-intrinsics-hide
+@cindex -fmil-intrinsics-disable option
+@cindex options, -fmil-intrinsics-disable
+@item -fmil-intrinsics-disable
+@cindex -fmil-intrinsics-enable option
+@cindex options, -fmil-intrinsics-enable
+@item -fmil-intrinsics-enable
+@cindex MIL-STD 1753
+@cindex intrinsics, MIL-STD 1753
+Specify status of MIL-STD-1753-specific intrinsics.
+@samp{-fmil-intrinsics-enable} is the default.
+@xref{Intrinsic Groups}.
+
+@cindex -funix-intrinsics-delete option
+@cindex options, -funix-intrinsics-delete
+@item -funix-intrinsics-delete
+@cindex -funix-intrinsics-hide option
+@cindex options, -funix-intrinsics-hide
+@item -funix-intrinsics-hide
+@cindex -funix-intrinsics-disable option
+@cindex options, -funix-intrinsics-disable
+@item -funix-intrinsics-disable
+@cindex -funix-intrinsics-enable option
+@cindex options, -funix-intrinsics-enable
+@item -funix-intrinsics-enable
+@cindex UNIX intrinsics
+@cindex intrinsics, UNIX
+Specify status of UNIX intrinsics.
+@samp{-funix-intrinsics-enable} is the default.
+@xref{Intrinsic Groups}.
+
+@cindex -fvxt-intrinsics-delete option
+@cindex options, -fvxt-intrinsics-delete
+@item -fvxt-intrinsics-delete
+@cindex -fvxt-intrinsics-hide option
+@cindex options, -fvxt-intrinsics-hide
+@item -fvxt-intrinsics-hide
+@cindex -fvxt-intrinsics-disable option
+@cindex options, -fvxt-intrinsics-disable
+@item -fvxt-intrinsics-disable
+@cindex -fvxt-intrinsics-enable option
+@cindex options, -fvxt-intrinsics-enable
+@item -fvxt-intrinsics-enable
+@cindex VXT intrinsics
+@cindex intrinsics, VXT
+Specify status of VXT intrinsics.
+@samp{-fvxt-intrinsics-enable} is the default.
+@xref{Intrinsic Groups}.
+
+@cindex -ffixed-line-length-@var{n} option
+@cindex options, -ffixed-line-length-@var{n}
+@item -ffixed-line-length-@var{n}
+@cindex source file format
+@cindex lines, length
+@cindex length of source lines
+@cindex fixed form
+@cindex limits, lengths of source lines
+Set column after which characters are ignored in typical fixed-form
+lines in the source file, and through which spaces are assumed (as
+if padded to that length) after the ends of short fixed-form lines.
+
+@cindex card image
+@cindex extended-source option
+Popular values for @var{n} include 72 (the
+standard and the default), 80 (card image), and 132 (corresponds
+to ``extended-source'' options in some popular compilers).
+@var{n} may be @samp{none}, meaning that the entire line is meaningful
+and that continued character constants never have implicit spaces appended
+to them to fill out the line.
+@samp{-ffixed-line-length-0} means the same thing as
+@samp{-ffixed-line-length-none}.
+
+@xref{Source Form}, for more information.
+@end table
+
+@node Warning Options
+@section Options to Request or Suppress Warnings
+@cindex options, warnings
+@cindex warnings, suppressing
+@cindex messages, warning
+@cindex suppressing warnings
+
+Warnings are diagnostic messages that report constructions which
+are not inherently erroneous but which are risky or suggest there
+might have been an error.
+
+You can request many specific warnings with options beginning @samp{-W},
+for example @samp{-Wimplicit} to request warnings on implicit
+declarations. Each of these specific warning options also has a
+negative form beginning @samp{-Wno-} to turn off warnings;
+for example, @samp{-Wno-implicit}. This manual lists only one of the
+two forms, whichever is not the default.
+
+These options control the amount and kinds of warnings produced by GNU
+Fortran:
+
+@table @code
+@cindex syntax checking
+@cindex -fsyntax-only option
+@cindex options, -fsyntax-only
+@item -fsyntax-only
+Check the code for syntax errors, but don't do anything beyond that.
+
+@cindex -pedantic option
+@cindex options, -pedantic
+@item -pedantic
+Issue warnings for uses of extensions to ANSI FORTRAN 77.
+@samp{-pedantic} also applies to C-language constructs where they
+occur in GNU Fortran source files, such as use of @samp{\e} in a
+character constant within a directive like @samp{#include}.
+
+Valid ANSI FORTRAN 77 programs should compile properly with or without
+this option.
+However, without this option, certain GNU extensions and traditional
+Fortran features are supported as well.
+With this option, many of them are rejected.
+
+Some users try to use @samp{-pedantic} to check programs for strict ANSI
+conformance.
+They soon find that it does not do quite what they want---it finds some
+non-ANSI practices, but not all.
+However, improvements to @code{g77} in this area are welcome.
+
+@cindex -pedantic-errors option
+@cindex options, -pedantic-errors
+@item -pedantic-errors
+Like @samp{-pedantic}, except that errors are produced rather than
+warnings.
+
+@cindex -fpedantic option
+@cindex options, -fpedantic
+@item -fpedantic
+Like @samp{-pedantic}, but applies only to Fortran constructs.
+
+@cindex -w option
+@cindex options, -w
+@item -w
+Inhibit all warning messages.
+
+@cindex -Wno-globals option
+@cindex options, -Wno-globals
+@item -Wno-globals
+@cindex global names, warning
+@cindex warnings, global names
+Inhibit warnings about use of a name as both a global name
+(a subroutine, function, or block data program unit, or a
+common block) and implicitly as the name of an intrinsic
+in a source file.
+
+Also inhibit warnings about inconsistent invocations and/or
+definitions of global procedures (function and subroutines).
+Such inconsistencies include different numbers of arguments
+and different types of arguments.
+
+@cindex -Wimplicit option
+@cindex options, -Wimplicit
+@item -Wimplicit
+@cindex implicit declaration, warning
+@cindex warnings, implicit declaration
+@cindex -u option
+@cindex /WARNINGS=DECLARATIONS switch
+@cindex IMPLICIT NONE, similar effect
+@cindex effecting IMPLICIT NONE
+Warn whenever a variable, array, or function is implicitly
+declared.
+Has an effect similar to using the @code{IMPLICIT NONE} statement
+in every program unit.
+(Some Fortran compilers provide this feature by an option
+named @samp{-u} or @samp{/WARNINGS=DECLARATIONS}.)
+
+@cindex -Wunused option
+@cindex options, -Wunused
+@item -Wunused
+@cindex unused variables
+@cindex variables, unused
+Warn whenever a variable is unused aside from its declaration.
+
+@cindex -Wuninitialized option
+@cindex options, -Wuninitialized
+@item -Wuninitialized
+@cindex uninitialized variables
+@cindex variables, uninitialized
+Warn whenever an automatic variable is used without first being initialized.
+
+These warnings are possible only in optimizing compilation,
+because they require data-flow information that is computed only
+when optimizing. If you don't specify @samp{-O}, you simply won't
+get these warnings.
+
+These warnings occur only for variables that are candidates for
+register allocation. Therefore, they do not occur for a variable
+@c that is declared @code{VOLATILE}, or
+whose address is taken, or whose size
+is other than 1, 2, 4 or 8 bytes. Also, they do not occur for
+arrays, even when they are in registers.
+
+Note that there might be no warning about a variable that is used only
+to compute a value that itself is never used, because such
+computations may be deleted by data-flow analysis before the warnings
+are printed.
+
+These warnings are made optional because GNU Fortran is not smart
+enough to see all the reasons why the code might be correct
+despite appearing to have an error. Here is one example of how
+this can happen:
+
+@example
+SUBROUTINE DISPAT(J)
+IF (J.EQ.1) I=1
+IF (J.EQ.2) I=4
+IF (J.EQ.3) I=5
+CALL FOO(I)
+END
+@end example
+
+@noindent
+If the value of @code{J} is always 1, 2 or 3, then @code{I} is
+always initialized, but GNU Fortran doesn't know this. Here is
+another common case:
+
+@example
+SUBROUTINE MAYBE(FLAG)
+LOGICAL FLAG
+IF (FLAG) VALUE = 9.4
+@dots{}
+IF (FLAG) PRINT *, VALUE
+END
+@end example
+
+@noindent
+This has no bug because @code{VALUE} is used only if it is set.
+
+@cindex -Wall option
+@cindex options, -Wall
+@item -Wall
+@cindex all warnings
+@cindex warnings, all
+The @samp{-Wunused} and @samp{-Wuninitialized} options combined.
+These are all the
+options which pertain to usage that we recommend avoiding and that we
+believe is easy to avoid.
+(As more warnings are added to @code{g77}, some might
+be added to the list enabled by @samp{-Wall}.)
+@end table
+
+The remaining @samp{-W@dots{}} options are not implied by @samp{-Wall}
+because they warn about constructions that we consider reasonable to
+use, on occasion, in clean programs.
+
+@table @code
+@c @item -W
+@c Print extra warning messages for these events:
+@c
+@c @itemize @bullet
+@c @item
+@c If @samp{-Wall} or @samp{-Wunused} is also specified, warn about unused
+@c arguments.
+@c
+@c @end itemize
+@c
+@cindex -Wsurprising option
+@cindex options, -Wsurprising
+@item -Wsurprising
+Warn about ``suspicious'' constructs that are interpreted
+by the compiler in a way that might well be surprising to
+someone reading the code.
+These differences can result in subtle, compiler-dependent
+(even machine-dependent) behavioral differences.
+The constructs warned about include:
+
+@itemize @bullet
+@item
+Expressions having two arithmetic operators in a row, such
+as @samp{X*-Y}.
+Such a construct is nonstandard, and can produce
+unexpected results in more complicated situations such
+as @samp{X**-Y*Z}.
+@code{g77}, along with many other compilers, interprets
+this example differently than many programmers, and a few
+other compilers.
+Specifically, @code{g77} interprets @samp{X**-Y*Z} as
+@samp{(X**(-Y))*Z}, while others might think it should
+be interpreted as @samp{X**(-(Y*Z))}.
+
+A revealing example is the constant expression @samp{2**-2*1.},
+which @code{g77} evaluates to .25, while others might evaluate
+it to 0., the difference resulting from the way precedence affects
+type promotion.
+
+(The @samp{-fpedantic} option also warns about expressions
+having two arithmetic operators in a row.)
+
+@item
+Expressions with a unary minus followed by an operand and then
+a binary operator other than plus or minus.
+For example, @samp{-2**2} produces a warning, because
+the precedence is @samp{-(2**2)}, yielding -4, not
+@samp{(-2)**2}, which yields 4, and which might represent
+what a programmer expects.
+
+An example of an expression producing different results
+in a surprising way is @samp{-I*S}, where @var{I} holds
+the value @samp{-2147483648} and @var{S} holds @samp{0.5}.
+On many systems, negating @var{I} results in the same
+value, not a positive number, because it is already the
+lower bound of what an @code{INTEGER(KIND=1)} variable can hold.
+So, the expression evaluates to a positive number, while
+the ``expected'' interpretation, @samp{(-I)*S}, would
+evaluate to a negative number.
+
+Even cases such as @samp{-I*J} produce warnings,
+even though, in most configurations and situations,
+there is no computational difference between the
+results of the two interpretations---the purpose
+of this warning is to warn about differing interpretations
+and encourage a better style of coding, not to identify
+only those places where bugs might exist in the user's
+code.
+
+@cindex DO statement
+@cindex statements, DO
+@item
+@code{DO} loops with @code{DO} variables that are not
+of integral type---that is, using @code{REAL}
+variables as loop control variables.
+Although such loops can be written to work in the
+``obvious'' way, the way @code{g77} is required by the
+Fortran standard to interpret such code is likely to
+be quite different from the way many programmers expect.
+(This is true of all @code{DO} loops, but the differences
+are pronounced for non-integral loop control variables.)
+
+@xref{Loops}, for more information.
+@end itemize
+
+@cindex -Werror option
+@cindex options, -Werror
+@item -Werror
+Make all warnings into errors.
+
+@cindex -W option
+@cindex options, -W
+@item -W
+@cindex extra warnings
+@cindex warnings, extra
+Turns on ``extra warnings'' and, if optimization is specified
+via @samp{-O}, the @samp{-Wuninitialized} option.
+(This might change in future versions of @code{g77}.)
+
+``Extra warnings'' are issued for:
+
+@itemize @bullet
+@item
+@cindex unused parameters
+@cindex parameters, unused
+@cindex unused arguments
+@cindex arguments, unused
+@cindex unused dummies
+@cindex dummies, unused
+Unused parameters to a procedure (when @samp{-Wunused} also is
+specified).
+
+@item
+@cindex overflow
+Overflows involving floating-point constants (not available
+for certain configurations).
+@end itemize
+@end table
+
+@xref{Warning Options,,Options to Request or Suppress Warnings,
+gcc,Using and Porting GNU CC}, for information on more options offered
+by the GBE shared by @code{g77}, @code{gcc}, and other GNU compilers.
+
+Some of these have no effect when compiling programs written in Fortran:
+
+@table @code
+@cindex -Wcomment option
+@cindex options, -Wcomment
+@item -Wcomment
+@cindex -Wformat option
+@cindex options, -Wformat
+@item -Wformat
+@cindex -Wparentheses option
+@cindex options, -Wparentheses
+@item -Wparentheses
+@cindex -Wswitch option
+@cindex options, -Wswitch
+@item -Wswitch
+@cindex -Wtraditional option
+@cindex options, -Wtraditional
+@item -Wtraditional
+@cindex -Wshadow option
+@cindex options, -Wshadow
+@item -Wshadow
+@cindex -Wid-clash-@var{len} option
+@cindex options, -Wid-clash-@var{len}
+@item -Wid-clash-@var{len}
+@cindex -Wlarger-than-@var{len} option
+@cindex options, -Wlarger-than-@var{len}
+@item -Wlarger-than-@var{len}
+@cindex -Wconversion option
+@cindex options, -Wconversion
+@item -Wconversion
+@cindex -Waggregate-return option
+@cindex options, -Waggregate-return
+@item -Waggregate-return
+@cindex -Wredundant-decls option
+@cindex options, -Wredundant-decls
+@item -Wredundant-decls
+@cindex unsupported warnings
+@cindex warnings, unsupported
+These options all could have some relevant meaning for
+GNU Fortran programs, but are not yet supported.
+@end table
+
+@node Debugging Options
+@section Options for Debugging Your Program or GNU Fortran
+@cindex options, debugging
+@cindex debugging information options
+
+GNU Fortran has various special options that are used for debugging
+either your program or @code{g77}.
+
+@table @code
+@cindex -g option
+@cindex options, -g
+@item -g
+Produce debugging information in the operating system's native format
+(stabs, COFF, XCOFF, or DWARF). GDB can work with this debugging
+information.
+@end table
+
+@xref{Debugging Options,,Options for Debugging Your Program or GNU CC,
+gcc,Using and Porting GNU CC}, for more information on debugging options.
+
+@node Optimize Options
+@section Options That Control Optimization
+@cindex optimize options
+@cindex options, optimization
+
+Most Fortran users will want to use no optimization when
+developing and testing programs, and use @samp{-O} or @samp{-O2} when
+compiling programs for late-cycle testing and for production use.
+However, note that certain diagnostics---such as for uninitialized
+variables---depend on the flow analysis done by @samp{-O}, i.e.@: you
+must use @samp{-O} or @samp{-O2} to get such diagnostics.
+
+The following flags have particular applicability when
+compiling Fortran programs:
+
+@table @code
+@cindex -malign-double option
+@cindex options, -malign-double
+@item -malign-double
+(Intel x86 architecture only.)
+
+Noticeably improves performance of @code{g77} programs making
+heavy use of @code{REAL(KIND=2)} (@code{DOUBLE PRECISION}) data
+on some systems.
+In particular, systems using Pentium, Pentium Pro, 586, and
+686 implementations
+of the i386 architecture execute programs faster when
+@code{REAL(KIND=2)} (@code{DOUBLE PRECISION}) data are
+aligned on 64-bit boundaries
+in memory.
+
+This option can, at least, make benchmark results more consistent
+across various system configurations, versions of the program,
+and data sets.
+
+@emph{Note:} The warning in the @code{gcc} documentation about
+this option does not apply, generally speaking, to Fortran
+code compiled by @code{g77}.
+
+@xref{Aligned Data}, for more information on alignment issues.
+
+@emph{Also also note:} The negative form of @samp{-malign-double}
+is @samp{-mno-align-double}, not @samp{-benign-double}.
+
+@cindex -ffloat-store option
+@cindex options, -ffloat-store
+@item -ffloat-store
+@cindex IEEE 754 conformance
+@cindex conformance, IEEE 754
+@cindex floating-point, precision
+Might help a Fortran program that depends on exact IEEE conformance on
+some machines, but might slow down a program that doesn't.
+
+This option is effective when the floating-point unit is set to work in
+IEEE 854 `extended precision'---as it typically is on x86 and m68k GNU
+systems---rather than IEEE 754 double precision. @samp{-ffloat-store}
+tries to remove the extra precision by spilling data from floating-point
+registers into memory and this typically involves a big performance
+hit. However, it doesn't affect intermediate results, so that it is
+only partially effective. `Excess precision' is avoided in code like:
+@smallexample
+a = b + c
+d = a * e
+@end smallexample
+but not in code like:
+@smallexample
+ d = (b + c) * e
+@end smallexample
+
+For another, potentially better, way of controlling the precision,
+see @ref{Floating-point precision}.
+
+@cindex -fforce-mem option
+@cindex options, -fforce-mem
+@item -fforce-mem
+@cindex -fforce-addr option
+@cindex options, -fforce-addr
+@item -fforce-addr
+@cindex loops, speeding up
+@cindex speed, of loops
+Might improve optimization of loops.
+
+@cindex -fno-inline option
+@cindex options, -fno-inline
+@item -fno-inline
+@cindex in-line code
+@cindex compilation, in-line
+@c DL: Only relevant for -O3?
+Don't compile statement functions inline.
+Might reduce the size of a program unit---which might be at
+expense of some speed (though it should compile faster).
+Note that if you are not optimizing, no functions can be expanded inline.
+
+@cindex -ffast-math option
+@cindex options, -ffast-math
+@item -ffast-math
+@cindex IEEE 754 conformance
+@cindex conformance, IEEE 754
+Might allow some programs designed to not be too dependent
+on IEEE behavior for floating-point to run faster, or die trying.
+Sets @samp{-funsafe-math-optimizations}, and
+@samp{-fno-trapping-math}.
+
+@cindex -funsafe-math-optimizations option
+@cindex options, -funsafe-math-optimizations
+@item -funsafe-math-optimizations
+Allow optimizations that may be give incorrect results
+for certain IEEE inputs.
+
+@cindex -fno-trapping-math option
+@cindex options, -fno-trapping-math
+@item -fno-trapping-math
+Allow the compiler to assume that floating-point arithmetic
+will not generate traps on any inputs. This is useful, for
+example, when running a program using IEEE "non-stop"
+floating-point arithmetic.
+
+@cindex -fstrength-reduce option
+@cindex options, -fstrength-reduce
+@item -fstrength-reduce
+@cindex loops, speeding up
+@cindex speed, of loops
+@c DL: normally defaulted?
+Might make some loops run faster.
+
+@cindex -frerun-cse-after-loop option
+@cindex options, -frerun-cse-after-loop
+@item -frerun-cse-after-loop
+@cindex -fexpensive-optimizations option
+@cindex options, -fexpensive-optimizations
+@c DL: This is -O2?
+@item -fexpensive-optimizations
+@cindex -fdelayed-branch option
+@cindex options, -fdelayed-branch
+@item -fdelayed-branch
+@cindex -fschedule-insns option
+@cindex options, -fschedule-insns
+@item -fschedule-insns
+@cindex -fschedule-insns2 option
+@cindex options, -fschedule-insns2
+@item -fschedule-insns2
+@cindex -fcaller-saves option
+@cindex options, -fcaller-saves
+@item -fcaller-saves
+Might improve performance on some code.
+
+@cindex -funroll-loops option
+@cindex options, -funroll-loops
+@item -funroll-loops
+@cindex loops, unrolling
+@cindex unrolling loops
+@cindex loops, optimizing
+@cindex indexed (iterative) @code{DO}
+@cindex iterative @code{DO}
+@c DL: fixme: Craig doesn't like `indexed' but f95 doesn't seem to
+@c provide a suitable term
+@c CB: I've decided on `iterative', for the time being, and changed
+@c my previous, rather bizarre, use of `imperative' to that
+@c (though `precomputed-trip' would be a more precise adjective)
+Typically improves performance on code using iterative @code{DO} loops by
+unrolling them and is probably generally appropriate for Fortran, though
+it is not turned on at any optimization level.
+Note that outer loop unrolling isn't done specifically; decisions about
+whether to unroll a loop are made on the basis of its instruction count.
+
+@c DL: Fixme: This should obviously go somewhere else...
+Also, no `loop discovery'@footnote{@dfn{loop discovery} refers to the
+process by which a compiler, or indeed any reader of a program,
+determines which portions of the program are more likely to be executed
+repeatedly as it is being run. Such discovery typically is done early
+when compiling using optimization techniques, so the ``discovered''
+loops get more attention---and more run-time resources, such as
+registers---from the compiler. It is easy to ``discover'' loops that are
+constructed out of looping constructs in the language
+(such as Fortran's @code{DO}). For some programs, ``discovering'' loops
+constructed out of lower-level constructs (such as @code{IF} and
+@code{GOTO}) can lead to generation of more optimal code
+than otherwise.} is done, so only loops written with @code{DO}
+benefit from loop optimizations, including---but not limited
+to---unrolling. Loops written with @code{IF} and @code{GOTO} are not
+currently recognized as such. This option unrolls only iterative
+@code{DO} loops, not @code{DO WHILE} loops.
+
+@cindex -funroll-all-loops option
+@cindex options, -funroll-all-loops
+@cindex DO WHILE
+@item -funroll-all-loops
+@c DL: Check my understanding of -funroll-all-loops v. -funroll-loops is correct.
+Probably improves performance on code using @code{DO WHILE} loops by
+unrolling them in addition to iterative @code{DO} loops. In the absence
+of @code{DO WHILE}, this option is equivalent to @samp{-funroll-loops}
+but possibly slower.
+
+@item -fno-move-all-movables
+@cindex -fno-move-all-movables option
+@cindex options, -fno-move-all-movables
+@item -fno-reduce-all-givs
+@cindex -fno-reduce-all-givs option
+@cindex options, -fno-reduce-all-givs
+@item -fno-rerun-loop-opt
+@cindex -fno-rerun-loop-opt option
+@cindex options, -fno-rerun-loop-opt
+@emph{Version info:}
+These options are not supported by
+versions of @code{g77} based on @code{gcc} version 2.8.
+
+Each of these might improve performance on some code.
+
+Analysis of Fortran code optimization and the resulting
+optimizations triggered by the above options were
+contributed by Toon Moene (@email{toon@@moene.indiv.nluug.nl}).
+
+These three options are intended to be removed someday, once
+they have helped determine the efficacy of various
+approaches to improving the performance of Fortran code.
+
+Please let us know how use of these options affects
+the performance of your production code.
+We're particularly interested in code that runs faster
+when these options are @emph{disabled}, and in
+non-Fortran code that benefits when they are
+@emph{enabled} via the above @code{gcc} command-line options.
+@end table
+
+@xref{Optimize Options,,Options That Control Optimization,
+gcc,Using and Porting GNU CC}, for more information on options
+to optimize the generated machine code.
+
+@node Preprocessor Options
+@section Options Controlling the Preprocessor
+@cindex preprocessor options
+@cindex options, preprocessor
+@cindex cpp program
+@cindex programs, cpp
+
+These options control the C preprocessor, which is run on each C source
+file before actual compilation.
+
+@xref{Preprocessor Options,,Options Controlling the Preprocessor,
+gcc,Using and Porting GNU CC}, for information on C preprocessor options.
+
+@cindex INCLUDE directive
+@cindex directive, INCLUDE
+Some of these options also affect how @code{g77} processes the
+@code{INCLUDE} directive.
+Since this directive is processed even when preprocessing
+is not requested, it is not described in this section.
+@xref{Directory Options,,Options for Directory Search}, for
+information on how @code{g77} processes the @code{INCLUDE} directive.
+
+However, the @code{INCLUDE} directive does not apply
+preprocessing to the contents of the included file itself.
+
+Therefore, any file that contains preprocessor directives
+(such as @code{#include}, @code{#define}, and @code{#if})
+must be included via the @code{#include} directive, not
+via the @code{INCLUDE} directive.
+Therefore, any file containing preprocessor directives,
+if included, is necessarily included by a file that itself
+contains preprocessor directives.
+
+@node Directory Options
+@section Options for Directory Search
+@cindex directory, options
+@cindex options, directory search
+@cindex search path
+
+These options affect how the @code{cpp} preprocessor searches
+for files specified via the @code{#include} directive.
+Therefore, when compiling Fortran programs, they are meaningful
+when the preprocessor is used.
+
+@cindex INCLUDE directive
+@cindex directive, INCLUDE
+Some of these options also affect how @code{g77} searches
+for files specified via the @code{INCLUDE} directive,
+although files included by that directive are not,
+themselves, preprocessed.
+These options are:
+
+@table @code
+@cindex -I- option
+@cindex options, -I-
+@item -I-
+@cindex -Idir option
+@cindex options, -Idir
+@item -I@var{dir}
+@cindex directory, search paths for inclusion
+@cindex inclusion, directory search paths for
+@cindex search paths, for included files
+@cindex paths, search
+These affect interpretation of the @code{INCLUDE} directive
+(as well as of the @code{#include} directive of the @code{cpp}
+preprocessor).
+
+Note that @samp{-I@var{dir}} must be specified @emph{without} any
+spaces between @samp{-I} and the directory name---that is,
+@samp{-Ifoo/bar} is valid, but @samp{-I foo/bar}
+is rejected by the @code{g77} compiler (though the preprocessor supports
+the latter form).
+@c this is due to toplev.c's inflexible option processing
+Also note that the general behavior of @samp{-I} and
+@code{INCLUDE} is pretty much the same as of @samp{-I} with
+@code{#include} in the @code{cpp} preprocessor, with regard to
+looking for @file{header.gcc} files and other such things.
+
+@xref{Directory Options,,Options for Directory Search,
+gcc,Using and Porting GNU CC}, for information on the @samp{-I} option.
+@end table
+
+@node Code Gen Options
+@section Options for Code Generation Conventions
+@cindex code generation, conventions
+@cindex options, code generation
+@cindex run-time, options
+
+These machine-independent options control the interface conventions
+used in code generation.
+
+Most of them have both positive and negative forms; the negative form
+of @samp{-ffoo} would be @samp{-fno-foo}. In the table below, only
+one of the forms is listed---the one which is not the default. You
+can figure out the other form by either removing @samp{no-} or adding
+it.
+
+@table @code
+@cindex -fno-automatic option
+@cindex options, -fno-automatic
+@item -fno-automatic
+@cindex SAVE statement
+@cindex statements, SAVE
+Treat each program unit as if the @code{SAVE} statement was specified
+for every local variable and array referenced in it.
+Does not affect common blocks.
+(Some Fortran compilers provide this option under
+the name @samp{-static}.)
+
+@cindex -finit-local-zero option
+@cindex options, -finit-local-zero
+@item -finit-local-zero
+@cindex DATA statement
+@cindex statements, DATA
+@cindex initialization, of local variables
+@cindex variables, initialization of
+@cindex uninitialized variables
+@cindex variables, uninitialized
+Specify that variables and arrays that are local to a program unit
+(not in a common block and not passed as an argument) are to be initialized
+to binary zeros.
+
+Since there is a run-time penalty for initialization of variables
+that are not given the @code{SAVE} attribute, it might be a
+good idea to also use @samp{-fno-automatic} with @samp{-finit-local-zero}.
+
+@cindex -fno-f2c option
+@cindex options, -fno-f2c
+@item -fno-f2c
+@cindex @code{f2c} compatibility
+@cindex compatibility, @code{f2c}
+Do not generate code designed to be compatible with code generated
+by @code{f2c}; use the GNU calling conventions instead.
+
+The @code{f2c} calling conventions require functions that return
+type @code{REAL(KIND=1)} to actually return the C type @code{double},
+and functions that return type @code{COMPLEX} to return the
+values via an extra argument in the calling sequence that points
+to where to store the return value.
+Under the GNU calling conventions, such functions simply return
+their results as they would in GNU C---@code{REAL(KIND=1)} functions
+return the C type @code{float}, and @code{COMPLEX} functions
+return the GNU C type @code{complex} (or its @code{struct}
+equivalent).
+
+This does not affect the generation of code that interfaces with the
+@code{libg2c} library.
+
+However, because the @code{libg2c} library uses @code{f2c}
+calling conventions, @code{g77} rejects attempts to pass
+intrinsics implemented by routines in this library as actual
+arguments when @samp{-fno-f2c} is used, to avoid bugs when
+they are actually called by code expecting the GNU calling
+conventions to work.
+
+For example, @samp{INTRINSIC ABS;CALL FOO(ABS)} is
+rejected when @samp{-fno-f2c} is in force.
+(Future versions of the @code{g77} run-time library might
+offer routines that provide GNU-callable versions of the
+routines that implement the @code{f2c}-callable intrinsics
+that may be passed as actual arguments, so that
+valid programs need not be rejected when @samp{-fno-f2c}
+is used.)
+
+@strong{Caution:} If @samp{-fno-f2c} is used when compiling any
+source file used in a program, it must be used when compiling
+@emph{all} Fortran source files used in that program.
+
+@c seems kinda dumb to tell people about an option they can't use -- jcb
+@c then again, we want users building future-compatible libraries with it.
+@cindex -ff2c-library option
+@cindex options, -ff2c-library
+@item -ff2c-library
+Specify that use of @code{libg2c} (or the original @code{libf2c})
+is required.
+This is the default for the current version of @code{g77}.
+
+Currently it is not
+valid to specify @samp{-fno-f2c-library}.
+This option is provided so users can specify it in shell
+scripts that build programs and libraries that require the
+@code{libf2c} library, even when being compiled by future
+versions of @code{g77} that might otherwise default to
+generating code for an incompatible library.
+
+@cindex -fno-underscoring option
+@cindex options, -fno-underscoring
+@item -fno-underscoring
+@cindex underscore
+@cindex symbol names, underscores
+@cindex transforming symbol names
+@cindex symbol names, transforming
+Do not transform names of entities specified in the Fortran
+source file by appending underscores to them.
+
+With @samp{-funderscoring} in effect, @code{g77} appends two underscores
+to names with underscores and one underscore to external names with
+no underscores. (@code{g77} also appends two underscores to internal
+names with underscores to avoid naming collisions with external names.
+The @samp{-fno-second-underscore} option disables appending of the
+second underscore in all cases.)
+
+This is done to ensure compatibility with code produced by many
+UNIX Fortran compilers, including @code{f2c}, which perform the
+same transformations.
+
+Use of @samp{-fno-underscoring} is not recommended unless you are
+experimenting with issues such as integration of (GNU) Fortran into
+existing system environments (vis-a-vis existing libraries, tools, and
+so on).
+
+For example, with @samp{-funderscoring}, and assuming other defaults like
+@samp{-fcase-lower} and that @samp{j()} and @samp{max_count()} are
+external functions while @samp{my_var} and @samp{lvar} are local variables,
+a statement like
+
+@smallexample
+I = J() + MAX_COUNT (MY_VAR, LVAR)
+@end smallexample
+
+@noindent
+is implemented as something akin to:
+
+@smallexample
+i = j_() + max_count__(&my_var__, &lvar);
+@end smallexample
+
+With @samp{-fno-underscoring}, the same statement is implemented as:
+
+@smallexample
+i = j() + max_count(&my_var, &lvar);
+@end smallexample
+
+Use of @samp{-fno-underscoring} allows direct specification of
+user-defined names while debugging and when interfacing @code{g77}-compiled
+code with other languages.
+
+Note that just because the names match does @emph{not} mean that the
+interface implemented by @code{g77} for an external name matches the
+interface implemented by some other language for that same name.
+That is, getting code produced by @code{g77} to link to code produced
+by some other compiler using this or any other method can be only a
+small part of the overall solution---getting the code generated by
+both compilers to agree on issues other than naming can require
+significant effort, and, unlike naming disagreements, linkers normally
+cannot detect disagreements in these other areas.
+
+Also, note that with @samp{-fno-underscoring}, the lack of appended
+underscores introduces the very real possibility that a user-defined
+external name will conflict with a name in a system library, which
+could make finding unresolved-reference bugs quite difficult in some
+cases---they might occur at program run time, and show up only as
+buggy behavior at run time.
+
+In future versions of @code{g77}, we hope to improve naming and linking
+issues so that debugging always involves using the names as they appear
+in the source, even if the names as seen by the linker are mangled to
+prevent accidental linking between procedures with incompatible
+interfaces.
+
+@cindex -fno-second-underscore option
+@cindex options, -fno-second-underscore
+@item -fno-second-underscore
+@cindex underscore
+@cindex symbol names, underscores
+@cindex transforming symbol names
+@cindex symbol names, transforming
+Do not append a second underscore to names of entities specified
+in the Fortran source file.
+
+This option has no effect if @samp{-fno-underscoring} is
+in effect.
+
+Otherwise, with this option, an external name such as @samp{MAX_COUNT}
+is implemented as a reference to the link-time external symbol
+@samp{max_count_}, instead of @samp{max_count__}.
+
+@cindex -fno-ident option
+@cindex options, -fno-ident
+@item -fno-ident
+Ignore the @samp{#ident} directive.
+
+@cindex -fzeros option
+@cindex options, -fzeros
+@item -fzeros
+Treat initial values of zero as if they were any other value.
+
+As of version 0.5.18, @code{g77} normally treats @code{DATA} and
+other statements that are used to specify initial values of zero
+for variables and arrays as if no values were actually specified,
+in the sense that no diagnostics regarding multiple initializations
+are produced.
+
+This is done to speed up compiling of programs that initialize
+large arrays to zeros.
+
+Use @samp{-fzeros} to revert to the simpler, slower behavior
+that can catch multiple initializations by keeping track of
+all initializations, zero or otherwise.
+
+@emph{Caution:} Future versions of @code{g77} might disregard this option
+(and its negative form, the default) or interpret it somewhat
+differently.
+The interpretation changes will affect only non-standard
+programs; standard-conforming programs should not be affected.
+
+@cindex -femulate-complex option
+@cindex options, -femulate-complex
+@item -femulate-complex
+Implement @code{COMPLEX} arithmetic via emulation,
+instead of using the facilities of
+the @code{gcc} back end that provide direct support of
+@code{complex} arithmetic.
+
+(@code{gcc} had some bugs in its back-end support
+for @code{complex} arithmetic, due primarily to the support not being
+completed as of version 2.8.1 and @code{egcs} 1.1.2.)
+
+Use @samp{-femulate-complex} if you suspect code-generation bugs,
+or experience compiler crashes,
+that might result from @code{g77} using the @code{COMPLEX} support
+in the @code{gcc} back end.
+If using that option fixes the bugs or crashes you are seeing,
+that indicates a likely @code{g77} bugs
+(though, all compiler crashes are considered bugs),
+so, please report it.
+(Note that the known bugs, now believed fixed, produced compiler crashes
+rather than causing the generation of incorrect code.)
+
+Use of this option should not affect how Fortran code compiled
+by @code{g77} works in terms of its interfaces to other code,
+e.g. that compiled by @code{f2c}.
+
+@emph{Caution:} Future versions of @code{g77} might ignore both forms
+of this option.
+
+@cindex -falias-check option
+@cindex options, -falias-check
+@cindex -fargument-alias option
+@cindex options, -fargument-alias
+@cindex -fargument-noalias option
+@cindex options, -fargument-noalias
+@cindex -fno-argument-noalias-global option
+@cindex options, -fno-argument-noalias-global
+@item -falias-check
+@item -fargument-alias
+@item -fargument-noalias
+@item -fno-argument-noalias-global
+@emph{Version info:}
+These options are not supported by
+versions of @code{g77} based on @code{gcc} version 2.8.
+
+These options specify to what degree aliasing
+(overlap)
+is permitted between
+arguments (passed as pointers) and @code{COMMON} (external, or
+public) storage.
+
+The default for Fortran code, as mandated by the FORTRAN 77 and
+Fortran 90 standards, is @samp{-fargument-noalias-global}.
+The default for code written in the C language family is
+@samp{-fargument-alias}.
+
+Note that, on some systems, compiling with @samp{-fforce-addr} in
+effect can produce more optimal code when the default aliasing
+options are in effect (and when optimization is enabled).
+
+@xref{Aliasing Assumed To Work}, for detailed information on the implications
+of compiling Fortran code that depends on the ability to alias dummy
+arguments.
+
+@cindex -fno-globals option
+@cindex options, -fno-globals
+@item -fno-globals
+@cindex global names, warning
+@cindex warnings, global names
+@cindex in-line code
+@cindex compilation, in-line
+Disable diagnostics about inter-procedural
+analysis problems, such as disagreements about the
+type of a function or a procedure's argument,
+that might cause a compiler crash when attempting
+to inline a reference to a procedure within a
+program unit.
+(The diagnostics themselves are still produced, but
+as warnings, unless @samp{-Wno-globals} is specified,
+in which case no relevant diagnostics are produced.)
+
+Further, this option disables such inlining, to
+avoid compiler crashes resulting from incorrect
+code that would otherwise be diagnosed.
+
+As such, this option might be quite useful when
+compiling existing, ``working'' code that happens
+to have a few bugs that do not generally show themselves,
+but which @code{g77} diagnoses.
+
+Use of this option therefore has the effect of
+instructing @code{g77} to behave more like it did
+up through version 0.5.19.1, when it paid little or
+no attention to disagreements between program units
+about a procedure's type and argument information,
+and when it performed no inlining of procedures
+(except statement functions).
+
+Without this option, @code{g77} defaults to performing
+the potentially inlining procedures as it started doing
+in version 0.5.20, but as of version 0.5.21, it also
+diagnoses disagreements that might cause such inlining
+to crash the compiler as (fatal) errors,
+and warns about similar disagreements
+that are currently believed to not
+likely to result in the compiler later crashing
+or producing incorrect code.
+
+@cindex -fflatten-arrays option
+@item -fflatten-arrays
+@cindex array performance
+@cindex arrays, flattening
+Use back end's C-like constructs
+(pointer plus offset)
+instead of its @code{ARRAY_REF} construct
+to handle all array references.
+
+@emph{Note:} This option is not supported.
+It is intended for use only by @code{g77} developers,
+to evaluate code-generation issues.
+It might be removed at any time.
+
+@cindex -fbounds-check option
+@cindex -ffortran-bounds-check option
+@item -fbounds-check
+@itemx -ffortran-bounds-check
+@cindex bounds checking
+@cindex range checking
+@cindex array bounds checking
+@cindex subscript checking
+@cindex substring checking
+@cindex checking subscripts
+@cindex checking substrings
+Enable generation of run-time checks for array subscripts
+and substring start and end points
+against the (locally) declared minimum and maximum values.
+
+The current implementation uses the @code{libf2c}
+library routine @code{s_rnge} to print the diagnostic.
+
+However, whereas @code{f2c} generates a single check per
+reference for a multi-dimensional array, of the computed
+offset against the valid offset range (0 through the size of the array),
+@code{g77} generates a single check per @emph{subscript} expression.
+This catches some cases of potential bugs that @code{f2c} does not,
+such as references to below the beginning of an assumed-size array.
+
+@code{g77} also generates checks for @code{CHARACTER} substring references,
+something @code{f2c} currently does not do.
+
+Use the new @samp{-ffortran-bounds-check} option
+to specify bounds-checking for only the Fortran code you are compiling,
+not necessarily for code written in other languages.
+
+@emph{Note:} To provide more detailed information on the offending subscript,
+@code{g77} provides the @code{libg2c} run-time library routine @code{s_rnge}
+with somewhat differently-formatted information.
+Here's a sample diagnostic:
+
+@smallexample
+Subscript out of range on file line 4, procedure rnge.f/bf.
+Attempt to access the -6-th element of variable b[subscript-2-of-2].
+Aborted
+@end smallexample
+
+The above message indicates that the offending source line is
+line 4 of the file @file{rnge.f},
+within the program unit (or statement function) named @samp{bf}.
+The offended array is named @samp{b}.
+The offended array dimension is the second for a two-dimensional array,
+and the offending, computed subscript expression was @samp{-6}.
+
+For a @code{CHARACTER} substring reference, the second line has
+this appearance:
+
+@smallexample
+Attempt to access the 11-th element of variable a[start-substring].
+@end smallexample
+
+This indicates that the offended @code{CHARACTER} variable or array
+is named @samp{a},
+the offended substring position is the starting (leftmost) position,
+and the offending substring expression is @samp{11}.
+
+(Though the verbage of @code{s_rnge} is not ideal
+for the purpose of the @code{g77} compiler,
+the above information should provide adequate diagnostic abilities
+to it users.)
+@end table
+
+@xref{Code Gen Options,,Options for Code Generation Conventions,
+gcc,Using and Porting GNU CC}, for information on more options
+offered by the GBE
+shared by @code{g77}, @code{gcc}, and other GNU compilers.
+
+Some of these do @emph{not} work when compiling programs written in Fortran:
+
+@table @code
+@cindex -fpcc-struct-return option
+@cindex options, -fpcc-struct-return
+@item -fpcc-struct-return
+@cindex -freg-struct-return option
+@cindex options, -freg-struct-return
+@item -freg-struct-return
+You should not use these except strictly the same way as you
+used them to build the version of @code{libg2c} with which
+you will be linking all code compiled by @code{g77} with the
+same option.
+
+@cindex -fshort-double option
+@cindex options, -fshort-double
+@item -fshort-double
+This probably either has no effect on Fortran programs, or
+makes them act loopy.
+
+@cindex -fno-common option
+@cindex options, -fno-common
+@item -fno-common
+Do not use this when compiling Fortran programs,
+or there will be Trouble.
+
+@cindex -fpack-struct option
+@cindex options, -fpack-struct
+@item -fpack-struct
+This probably will break any calls to the @code{libg2c} library,
+at the very least, even if it is built with the same option.
+@end table
+
+@node Environment Variables
+@section Environment Variables Affecting GNU Fortran
+@cindex environment variables
+
+GNU Fortran currently does not make use of any environment
+variables to control its operation above and beyond those
+that affect the operation of @code{gcc}.
+
+@xref{Environment Variables,,Environment Variables Affecting GNU CC,
+gcc,Using and Porting GNU CC}, for information on environment
+variables.
projects / platform / upstream / linaro-gcc.git / commitdiff