This section describes changes to g77
that are visible
to the programmers who actually write and maintain Fortran
code they compile with g77
.
Information on changes to installation procedures,
changes to the documentation, and bug fixes is
not provided here, unless it is likely to affect how
users use g77
.
See section News About GNU Fortran, for information on
such changes to g77
.
To find out about existing bugs and ongoing plans for GNU Fortran, retrieve @url{ftp://alpha.gnu.ai.mit.edu/g77.plan} or, if you cannot do that, email @email{fortran@gnu.ai.mit.edu} asking for a recent copy of the GNU Fortran `.plan' file.
INTEGER(KIND=1)
constants.
Specify `-ftypeless-boz' to cause such
constants to be interpreted as typeless.
(Version 0.5.19 introduced `-fno-typeless-boz' and
its inverse.)
See section Options Controlling Fortran Dialect,
for information on the `-ftypeless-boz' option.
libU77
intrinsics.
Users of such programs might need to compile them
differently (using, for example, `-ff90-intrinsics-disable')
or, better yet, insert appropriate EXTERNAL
statements specifying that these names are not intended
to be names of intrinsics.
libf2c
, which should result in improved
I/O performance, especially over NFS.
Note: If you have code that depends on the behavior
of libf2c
when built with `ALWAYS_FLUSH' defined,
you will have to modify libf2c
accordingly before
building it from this and future versions of g77
.
See section Output Assumed To Flush, for more information.
libU77
has been
added to the version of libf2c
distributed with
and built by g77
.
g77
now knows about the routines in this library
as intrinsics.
g77
.
See section Other Dialects, for more information.
LOC()
intrinsic and %LOC()
construct now return
values of INTEGER(KIND=0)
type,
as defined by the GNU Fortran language.
This type is wide enough
(holds the same number of bits)
as the character-pointer type on the machine.
On most systems, this won't make a noticable difference,
whereas on Alphas and other systems with 64-bit pointers,
the INTEGER(KIND=0)
type is equivalent to INTEGER(KIND=2)
(often referred to as INTEGER*8
)
instead of the more common INTEGER(KIND=1)
(often referred to as INTEGER*4
).
COMPLEX
arithmetic in the g77
front
end, to avoid bugs in complex
support in the
gcc
back end.
New option `-fno-emulate-complex'
causes g77
to revert the 0.5.19 behavior.
COMMON
areas when any of
these are defined (assigned to) by Fortran code.
This can result in faster and/or smaller programs when
compiling with optimization enabled, though on some
systems this effect is observed only when `-fforce-addr'
also is specified.
New options `-falias-check', `-fargument-alias',
`-fargument-noalias',
and `-fno-argument-noalias-global' control the
way g77
handles potential aliasing.
See section Aliasing Assumed To Work, for detailed information on why the
new defaults might result in some programs no longer working the way they
did when compiled by previous versions of g77
.
g77
uses a separate memory location
to hold assigned statement labels.)
See section Ugly Assigned Labels, for more information.
FORMAT
and ENTRY
statements now are allowed to
precede IMPLICIT NONE
statements.
INTEGER(KIND=2)
(often referred to as INTEGER*8
)
available in
libf2c
and `f2c.h' so that f2c
users
may make full use of its features via the g77
version of `f2c.h' and the INTEGER(KIND=2)
support routines in the g77
version of libf2c
.
g77
driver and libf2c
so that `g77 -v'
yields version information on the library.
SNGL
and FLOAT
intrinsics now are
specific intrinsics, instead of synonyms for the
generic intrinsic REAL
.
REALPART
, IMAGPART
,
COMPLEX
,
LONG
, and SHORT
.
REALPART
, IMAGPART
,
and COMPLEX
intrinsics.
An old group, `dcp', has been removed.
COMMON
and EQUIVALENCE
members at debug time.
See section Options for Code Generation Conventions,
for information on the `-fdebug-kludge' option.
DO
loops.
f77
and f2c
.
INTEGER(KIND=1)
constants.
f77
programs.
libf2c
that might return non-zero
status codes for some operations previously assumed to always
return zero.
This change not only affects how IOSTAT=
variables
are set by list-directed I/O, it also affects whether
END=
and ERR=
labels are reached by these
operations.
FTELL
and FSEEK
procedures in libf2c
.
g77
command, to conform to GNU coding guidelines.
Also add printing of g77
version number when
the `--verbose' (`-v') option is used.
BYTE
and WORD
statements now are supported,
to a limited extent.
INTEGER*1
, INTEGER*2
, INTEGER*8
,
and their LOGICAL
equivalents, now are supported to a limited extent.
Among the missing elements are complete intrinsic and constant
support.
g77
-aware GNU compilers---`-fmove-all-movables',
`-freduce-all-givs', and `-frerun-loop-opt'---which
can improve the run-time performance of some programs.
ERF()
and ERFC()
intrinsics now are generic
intrinsics, mapping to ERF
/DERF
and
ERFC
/DERFC
, respectively.
Note: Use `INTRINSIC ERF,ERFC' in any code that
might reference these as generic intrinsics, to
improve the likelihood of diagnostics (instead of subtle run-time
bugs) when using compilers that don't support these as intrinsics.
INTEGER
variables now diagnosed only when
`-Wsurprising' specified.
Previously, this was diagnosed unless `-fpedantic' or
`-fugly' was specified.
libf2c
changed to output a leading zero (0) digit for floating-point
values output via list-directed and formatted output (to bring g77
more into line with many existing Fortran implementations--the
ANSI FORTRAN 77 standard leaves this choice to the implementation).
libf2c
no longer built with debugging information
intact, making it much smaller.
g77
command now works.
gcc
,
including messages like `In function `foo':' and `In file
included from...:'.
ABORT
,
DERF
, DERFC
, ERF
, ERFC
, EXIT
,
FLUSH
, GETARG
, GETENV
, SIGNAL
, and
SYSTEM
.
g77
command.
gcc
options `-fident' and `-fno-ident'
added.
g77
command to better fulfill its role as
a front-end to the gcc
driver.
For example, g77
now
recognizes `--verbose' as a verbose way of specifying `-v'.
Go to the first, previous, next, last section, table of contents.