g77(1)
NAME
g77 - GNU project Fortran 77 compiler
SYNOPSIS
g77 [-c|-S|-E]
[-g] [-pg] [-Olevel]
[-Wwarn...] [-pedantic]
[-Idir...] [-Ldir...]
[-Dmacro[=defn]...] [-Umacro]
[-foption...] [-mmachine-option...]
[-o outfile] infile...
Only the most useful options are listed here; see below
for the remainder.
DESCRIPTION
The g77 command supports all the options supported by the
gcc command.
All gcc and g77 options are accepted both by g77 and by
gcc (as well as any other drivers built at the same time,
such as g++), since adding g77 to the gcc distribution
enables acceptance of g77 options by all of the relevant
drivers.
In some cases, options have positive and negative forms;
the negative form of -ffoo would be -fno-foo. This manual
documents only one of these two forms, whichever one is
not the default.
OPTIONS
Here is a summary of all the options specific to GNU For
tran, grouped by type. Explanations are in the following
sections.
ArrayThis indicates that the offended "CHARACTER" variable
or array is named a, the offended substring position
is the starting (leftmost) position, and the offending
substring expression is 11.
- (Though the verbage of "s_rnge" is not ideal for the
purpose of the g77 compiler, the above information should provide adequate diagnostic abilities to it
users.) - Some of these do not work when compiling programs written
in Fortran: - -fpcc-struct-return
-freg-struct-return
You should not use these except strictly the same way
as you used them to build the version of "libg2c" with
which you will be linking all code compiled by g77 with the same option. - -fshort-double
This probably either has no effect on Fortran pro
grams, or makes them act loopy. - -fno-common
Do not use this when compiling Fortran programs, or
there will be Trouble. - -fpack-struct
This probably will break any calls to the "libg2c"
library, at the very least, even if it is built with
the same option.
ENVIRONMENT
GNU Fortran currently does not make use of any environment
variables to control its operation above and beyond those
that affect the operation of gcc.
BUGS
For instructions on reporting bugs, see
<http://gcc.gnu.org/bugs.html>. Use of the gccbug script
to report bugs is recommended.
FOOTNOTES
- 1. loop discovery refers to the process by which a com
- piler, 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 discov
ery 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 "DO").
For some programs, ``discovering'' loops constructed
out of lower-level constructs (such as "IF" and
"GOTO") can lead to generation of more optimal code
than otherwise.
SEE ALSO
gpl(7), gfdl(7), fsf-funding(7), cpp(1), gcov(1), gcc(1), as(1), ld(1), gdb(1), adb(1), dbx(1), sdb(1) and the Info entries for gcc, cpp, g77, as, ld, binutils and gdb.
AUTHOR
See the Info entry for g77 for contributors to GCC and
G77.
COPYRIGHT
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002
Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify
this document under the terms of the GNU Free Documenta
tion License, Version 1.1 or any later version published
by the Free Software Foundation; with the Invariant Sec
tions being ``GNU General Public License'' and ``Funding
Free Software'', the Front-Cover texts being (a) (see
below), and with the Back-Cover Texts being (b) (see
below). A copy of the license is included in the gfdl(7)
man page.
- Arrayfunds for GNU development.