Skip to content

R
riscv-gcc-1
Commit 3994c6b1 by Tobias Burnus Committed by Tobias Burnus
Options

gfortran.texi: Add second space after end-of-sentence period... 

2010-09-24  Tobias Burnus  <burnus@net-b.de>

        * gfortran.texi: Add second space after end-of-sentence period;
        change / to /@/ to allow hyphenation of URLs.
        (Standards): Remove duplicated OpenMP, update wording given that
        Fortran 2008 now released.
        (Fortran 2008 status): Update and add list of implemented features.

From-SVN: r164584
parent 6fd71fde
Showing with 221 additions and 140 deletions
gcc/fortran/ChangeLog
2010-09-24 Tobias Burnus <burnus@net-b.de>
* gfortran.texi: Add second space after end-of-sentence period;
change / to /@/ to allow hyphenation of URLs.
(Standards): Remove duplicated OpenMP, update wording given that
Fortran 2008 now released.
(Fortran 2008 status): Update and add list of implemented features.
2010-09-24 Tobias Burnus <burnus@net-b.de>
PR fortran/40571
* iso-fortran-env.def: Add NAMED_KINDARRAY with
character_kinds, integer_kinds, logical_kinds and
......
gcc/fortran/gfortran.texi
\input texinfo @c -*-texinfo-*-
@c %**start of header
@setfilename gfortran.info
@set copyrights-gfortran 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
......@@ -158,7 +158,7 @@ Boston, MA 02110-1301, USA@*
@cindex Introduction
This manual documents the use of @command{gfortran},
the GNU Fortran compiler. You can find in this manual how to invoke
the GNU Fortran compiler. You can find in this manual how to invoke
@command{gfortran}, as well as its features and incompatibilities.
@ifset DEVELOPMENT
......@@ -208,7 +208,7 @@ Part II: Language Reference
@c The following duplicates the text on the TexInfo table of contents.
@iftex
This manual documents the use of @command{gfortran}, the GNU Fortran
compiler. You can find in this manual how to invoke @command{gfortran},
compiler. You can find in this manual how to invoke @command{gfortran},
as well as its features and incompatibilities.
@ifset DEVELOPMENT
......@@ -243,7 +243,7 @@ or alternative to, the unix @command{f95} command;
The GNU Fortran compiler supports the Fortran 77, 90 and 95 standards
completely, parts of the Fortran 2003 and Fortran 2008 standards, and
several vendor extensions. The development goal is to provide the
several vendor extensions. The development goal is to provide the
following features:
@itemize @bullet
......@@ -364,11 +364,11 @@ Functionally, this is implemented with a driver program (@command{gcc})
which provides the command-line interface for the compiler. It calls
the relevant compiler front-end program (e.g., @command{f951} for
Fortran) for each file in the source code, and then calls the assembler
and linker as appropriate to produce the compiled output. In a copy of
and linker as appropriate to produce the compiled output. In a copy of
GCC which has been compiled with Fortran language support enabled,
@command{gcc} will recognize files with @file{.f}, @file{.for}, @file{.ftn},
@file{.f90}, @file{.f95}, @file{.f03} and @file{.f08} extensions as
Fortran source code, and compile it accordingly. A @command{gfortran}
Fortran source code, and compile it accordingly. A @command{gfortran}
driver program is also provided, which is identical to @command{gcc}
except that it automatically links the Fortran runtime libraries into the
compiled program.
......@@ -378,7 +378,7 @@ Source files with @file{.f}, @file{.for}, @file{.fpp}, @file{.ftn}, @file{.F},
Source files with @file{.f90}, @file{.f95}, @file{.f03}, @file{.f08},
@file{.F90}, @file{.F95}, @file{.F03} and @file{.F08} extensions are
treated as free form. The capitalized versions of either form are run
through preprocessing. Source files with the lower case @file{.fpp}
through preprocessing. Source files with the lower case @file{.fpp}
extension are also run through preprocessing.
This manual specifically documents the Fortran front end, which handles
......@@ -404,28 +404,28 @@ Fortran compiler.
Many Fortran compilers including GNU Fortran allow passing the source code
through a C preprocessor (CPP; sometimes also called the Fortran preprocessor,
FPP) to allow for conditional compilation. In the case of GNU Fortran,
this is the GNU C Preprocessor in the traditional mode. On systems with
FPP) to allow for conditional compilation. In the case of GNU Fortran,
this is the GNU C Preprocessor in the traditional mode. On systems with
case-preserving file names, the preprocessor is automatically invoked if the
filename extension is @code{.F}, @code{.FOR}, @code{.FTN}, @code{.fpp},
@code{.FPP}, @code{.F90}, @code{.F95}, @code{.F03} or @code{.F08}. To manually
filename extension is @file{.F}, @file{.FOR}, @file{.FTN}, @file{.fpp},
@file{.FPP}, @file{.F90}, @file{.F95}, @file{.F03} or @file{.F08}. To manually
invoke the preprocessor on any file, use @option{-cpp}, to disable
preprocessing on files where the preprocessor is run automatically, use
@option{-nocpp}.
If a preprocessed file includes another file with the Fortran @code{INCLUDE}
statement, the included file is not preprocessed. To preprocess included
statement, the included file is not preprocessed. To preprocess included
files, use the equivalent preprocessor statement @code{#include}.
If GNU Fortran invokes the preprocessor, @code{__GFORTRAN__}
is defined and @code{__GNUC__}, @code{__GNUC_MINOR__} and
@code{__GNUC_PATCHLEVEL__} can be used to determine the version of the
compiler. See @ref{Top,,Overview,cpp,The C Preprocessor} for details.
compiler. See @ref{Top,,Overview,cpp,The C Preprocessor} for details.
While CPP is the de-facto standard for preprocessing Fortran code,
Part 3 of the Fortran 95 standard (ISO/IEC 1539-3:1998) defines
Conditional Compilation, which is not widely used and not directly
supported by the GNU Fortran compiler. You can use the program coco
supported by the GNU Fortran compiler. You can use the program coco
to preprocess such files (@uref{http://www.daniellnagle.com/coco.html}).
......@@ -474,9 +474,8 @@ standard-compliant Fortran 95, Fortran 90, and Fortran 77 programs,
including a number of standard and non-standard extensions, and can be
used on real-world programs. In particular, the supported extensions
include OpenMP, Cray-style pointers, and several Fortran 2003 and Fortran
2008 features such as enumeration, stream I/O, and some of the
enhancements to allocatable array support from TR 15581. However, it is
still under development and has a few remaining rough edges.
2008 features, including TR 15581. However, it is still under
development and has a few remaining rough edges.
At present, the GNU Fortran compiler passes the
@uref{http://www.fortran-2000.com/ArnaudRecipes/fcvs21_f95.html,
......@@ -491,7 +490,7 @@ large real-world programs, including
@uref{http://mysite.verizon.net/serveall/moene.pdf, the HIRLAM
weather-forecasting code} and
@uref{http://www.theochem.uwa.edu.au/tonto/, the Tonto quantum
chemistry package}; see @url{http://gcc.gnu.org/wiki/GfortranApps} for an
chemistry package}; see @url{http://gcc.gnu.org/@/wiki/@/GfortranApps} for an
extended list.
Among other things, the GNU Fortran compiler is intended as a replacement
......@@ -521,25 +520,17 @@ future standards---in particular, Fortran 2003 and Fortran 2008.
The GNU Fortran compiler implements
ISO/IEC 1539:1997 (Fortran 95). As such, it can also compile essentially all
standard-compliant Fortran 90 and Fortran 77 programs. It also supports
the ISO/IEC TR-15581 enhancements to allocatable arrays, and
the @uref{http://www.openmp.org/drupal/mp-documents/spec25.pdf,
OpenMP Application Program Interface v2.5} specification.
the ISO/IEC TR-15581 enhancements to allocatable arrays.
In the future, the GNU Fortran compiler will also support ISO/IEC
1539-1:2004 (Fortran 2003) and future Fortran standards. Partial support
of that standard is already provided; the current status of Fortran 2003
support is reported in the @ref{Fortran 2003 status} section of the
documentation.
The next version of the Fortran standard (Fortran 2008) is currently
being developed and the GNU Fortran compiler supports some of its new
features. This support is based on the latest draft of the standard
(available from @url{http://www.nag.co.uk/sc22wg5/}) and no guarantee of
future compatibility is made, as the final standard might differ from the
draft. For more information, see the @ref{Fortran 2008 status} section.
1539-1:2004 (Fortran 2003), ISO/IEC 1539-1:2010 (Fortran 2008) and
future Fortran standards. Partial support of the Fortran 2003 and
Fortran 2008 standard is already provided; the current status of the
support is reported in the @ref{Fortran 2003 status} and
@ref{Fortran 2008 status} sections of the documentation.
Additionally, the GNU Fortran compilers supports the OpenMP specification
(version 3.0, @url{http://openmp.org/wp/openmp-specifications/}).
(version 3.0, @url{http://openmp.org/@/wp/@/openmp-specifications/}).
@node Varying Length Character Strings
@subsection Varying Length Character Strings
......@@ -548,9 +539,9 @@ Additionally, the GNU Fortran compilers supports the OpenMP specification
@cindex strings, varying length
The Fortran 95 standard specifies in Part 2 (ISO/IEC 1539-2:2000)
varying length character strings. While GNU Fortran currently does not
varying length character strings. While GNU Fortran currently does not
support such strings directly, there exist two Fortran implementations
for them, which work with GNU Fortran. They can be found at
for them, which work with GNU Fortran. They can be found at
@uref{http://www.fortran.com/@/iso_varying_string.f95} and at
@uref{ftp://ftp.nag.co.uk/@/sc22wg5/@/ISO_VARYING_STRING/}.
......@@ -627,7 +618,7 @@ The default value is 0.
This environment variable controls where library output is sent.
If the first letter is @samp{y}, @samp{Y} or @samp{1}, standard
error is used. If the first letter is @samp{n}, @samp{N} or
error is used. If the first letter is @samp{n}, @samp{N} or
@samp{0}, standard output is used.
@node GFORTRAN_TMPDIR
......@@ -643,7 +634,7 @@ If these are missing, the default is @file{/tmp}.
This environment variable controls whether all I/O is unbuffered. If
the first letter is @samp{y}, @samp{Y} or @samp{1}, all I/O is
unbuffered. This will slow down small sequential reads and writes. If
unbuffered. This will slow down small sequential reads and writes. If
the first letter is @samp{n}, @samp{N} or @samp{0}, I/O is buffered.
This is the default.
......@@ -652,7 +643,7 @@ This is the default.
The environment variable named @env{GFORTRAN_UNBUFFERED_PRECONNECTED} controls
whether I/O on a preconnected unit (i.e.@: STDOUT or STDERR) is unbuffered. If
the first letter is @samp{y}, @samp{Y} or @samp{1}, I/O is unbuffered. This
the first letter is @samp{y}, @samp{Y} or @samp{1}, I/O is unbuffered. This
will slow down small sequential reads and writes. If the first letter
is @samp{n}, @samp{N} or @samp{0}, I/O is buffered. This is the default.
......@@ -662,7 +653,7 @@ is @samp{n}, @samp{N} or @samp{0}, I/O is buffered. This is the default.
If the first letter is @samp{y}, @samp{Y} or @samp{1}, filename and
line numbers for runtime errors are printed. If the first letter is
@samp{n}, @samp{N} or @samp{0}, don't print filename and line numbers
for runtime errors. The default is to print the location.
for runtime errors. The default is to print the location.
@node GFORTRAN_OPTIONAL_PLUS
@section @env{GFORTRAN_OPTIONAL_PLUS}---Print leading + where permitted
......@@ -671,7 +662,7 @@ If the first letter is @samp{y}, @samp{Y} or @samp{1},
a plus sign is printed
where permitted by the Fortran standard. If the first letter
is @samp{n}, @samp{N} or @samp{0}, a plus sign is not printed
in most cases. Default is not to print plus signs.
in most cases. Default is not to print plus signs.
@node GFORTRAN_DEFAULT_RECL
@section @env{GFORTRAN_DEFAULT_RECL}---Default record length for new files
......@@ -768,8 +759,8 @@ users who do not have the source code of their program available.
If the @env{GFORTRAN_ERROR_DUMPCORE} variable is set to
@samp{y}, @samp{Y} or @samp{1} (only the first letter is relevant)
then library run-time errors cause core dumps. To disable the core
dumps, set the variable to @samp{n}, @samp{N}, @samp{0}. Default
then library run-time errors cause core dumps. To disable the core
dumps, set the variable to @samp{n}, @samp{N}, @samp{0}. Default
is not to core dump unless the @option{-fdump-core} compile option
was used.
......@@ -780,7 +771,7 @@ If the @env{GFORTRAN_ERROR_BACKTRACE} variable is set to
@samp{y}, @samp{Y} or @samp{1} (only the first letter is relevant)
then a backtrace is printed when a run-time error occurs.
To disable the backtracing, set the variable to
@samp{n}, @samp{N}, @samp{0}. Default is not to print a backtrace
@samp{n}, @samp{N}, @samp{0}. Default is not to print a backtrace
unless the @option{-fbacktrace} compile option
was used.
......@@ -820,7 +811,7 @@ Intrinsics @code{command_argument_count}, @code{get_command},
@item
@cindex array, constructors
@cindex @code{[...]}
Array constructors using square brackets. That is, @code{[...]} rather
Array constructors using square brackets. That is, @code{[...]} rather
than @code{(/.../)}. Type-specification for array constructors like
@code{(/ some-type :: ... /)}.
......@@ -938,21 +929,103 @@ Extension of derived-types (the @code{EXTENDS(...)} syntax).
@node Fortran 2008 status
@section Fortran 2008 status
The next version of the Fortran standard after Fortran 2003 is currently
being worked on by the Working Group 5 of Sub-Committee 22 of the Joint
Technical Committee 1 of the International Organization for
Standardization (ISO) and the International Electrotechnical Commission
(IEC). This group is known as @uref{http://www.nag.co.uk/sc22wg5/, WG5}.
The next revision of the Fortran standard is informally referred to as
Fortran 2008, reflecting its planned release year. The GNU Fortran
compiler has support for some of the new features in Fortran 2008. This
support is based on the latest draft, available from
@url{http://www.nag.co.uk/sc22wg5/}. However, as the final standard may
differ from the drafts, no guarantee of backward compatibility can be
made and you should only use it for experimental purposes.
The latest version of the Fortran standard is ISO/IEC 1539-1:2010, informally
known as Fortran 2008. The official version is available from International
Organization for Standardization (ISO) or its national member organizations.
The the final draft (FDIS) can be downloaded free of charge from
@url{http://www.nag.co.uk/@/sc22wg5/@/links.html}. Fortran is developed by the
Working Group 5 of Sub-Committee 22 of the Joint Technical Committee 1 of the
International Organization for Standardization and the International
Electrotechnical Commission (IEC). This group is known as
@uref{http://www.nag.co.uk/sc22wg5/, WG5}.
The GNU Fortran supports several of the new features of Fortran 2008; the
@uref{http://gcc.gnu.org/wiki/Fortran2008Status, wiki} has some information
about the current Fortran 2008 implementation status. In particular, the
following is implemented.
@itemize
@item The @option{-std=f2008} option and support for the file extensions
@file{.f08} and @file{.F08}.
@item The @code{OPEN} statement now supports the @code{NEWUNIT=} option,
which returns a unique file unit, thus preventing inadvertent use of the
same unit in different parts of the program.
@item The @code{g0} format descriptor and unlimited format items.
@item The mathematical intrinsics @code{ASINH}, @code{ACOSH}, @code{ATANH},
@code{ERF}, @code{ERFC}, @code{GAMMA}, @code{LOG_GAMMA}, @code{BESSEL_J0},
@code{BESSEL_J1}, @code{BESSEL_JN}, @code{BESSEL_Y0}, @code{BESSEL_Y1},
@code{BESSEL_YN}, @code{HYPOT}, @code{NORM2}, and @code{ERFC_SCALED}.
@item Using complex arguments with @code{TAN}, @code{SINH}, @code{COSH},
@code{TANH}, @code{ASIN}, @code{ACOS}, and @code{ATAN} is now possible;
@code{ATAN}(@var{Y},@var{X}) is now an alias for @code{ATAN2}(@var{Y},@var{X}).
@item Support of the @code{PARITY} intrinsic functions.
@item The following bit intrinsics: @code{LEADZ} and @code{TRAILZ} for
counting the number of leading and trailing zero bits, @code{POPCNT} and
@code{POPPAR} for counting the number of one bits and returning the parity;
@code{BGE}, @code{BGT}, @code{BLE}, and @code{BLT} for bitwise comparisons;
@code{DSHIFTL} and @code{DSHIFTR} for combined left and right shifts,
@code{MASKL} and @code{MASKR} for simple left and right justified masks,
@code{MERGE_BITS} for a bitwise merge using a mask, @code{SHIFTA},
@code{SHIFTL} and @code{SHIFTR} for shift operations, and the
transformational bit intrinsics @code{IALL}, @code{IANY} and @code{IPARITY}.
@item Support of the @code{EXECUTE_COMMAND_LINE} intrinsic subroutine.
@item Support for the @code{STORAGE_SIZE} intrinsic inquiry function.
@item The @code{INT@{8,16,32@}} and @code{REAL@{32,64,128@}} kind type
parameters of the intrinsic module @code{ISO_FORTRAN_ENV}.
@item Experimental coarray support (for one image only), use the
@option{-fcoarray=single} flag to enable it.
@item The @code{BLOCK} construct is supported.
@item The @code{STOP} and the new @code{ERROR STOP} statements now
support all constant expressions.
@item Support for the @code{CONTIGUOUS} attribute.
@item Support for @code{ALLOCATE} with @code{MOLD}.
@item Support for the @code{IMPURE} attribute for procedures, which
allows for @code{ELEMENTAL} procedures without the restrictions of
@code{PURE}.
@item Null pointers (including @code{NULL()}) and not-allocated variables
can be used as actual argument to optional non-pointer, non-allocatable
dummy arguments, denoting an absent argument.
@item Non-pointer variables with @code{TARGET} attribute can be used as
actual argument to @code{POINTER} dummies with @code{INTENT(IN)}.
@item Pointers including procedure pointers and those in a derived
type (pointer components) can now be initialized by a target instead
of only by @code{NULL}.
@item The @code{EXIT} statement (with construct-name) can be now be
used to leave not only the @code{DO} but also the @code{ASSOCIATE},
@code{BLOCK}, @code{IF}, @code{SELECT CASE} and @code{SELECT TYPE}
constructs.
@item Internal procedures can now be used as actual argument.
@item Minor features: obsolesce diagnostics for @code{ENTRY} with
@option{-std=f2008}; a line may start with a semicolon; for internal
and module procedures @code{END} can be used instead of
@code{END SUBROUTINE} and @code{END FUNCTION}; @code{SELECTED_REAL_KIND}
now also takes a @code{RADIX} argument; intrinsic types are supported
for @code{TYPE}(@var{intrinsic-type-spec}); multiple type-bound procedures
can be declared in a single @code{PROCEDURE} statement; implied-shape
arrays are supported for named constants (@code{PARAMETER}).
@end itemize
The @uref{http://gcc.gnu.org/wiki/Fortran2008Status, wiki} has some information
about the current Fortran 2008 implementation status.
@c ---------------------------------------------------------------------
......@@ -1025,7 +1098,7 @@ as follows.
A @code{LOGICAL(KIND=N)} variable is represented as an
@code{INTEGER(KIND=N)} variable, however, with only two permissible
values: @code{1} for @code{.TRUE.} and @code{0} for
@code{.FALSE.}. Any other integer value results in undefined behavior.
@code{.FALSE.}. Any other integer value results in undefined behavior.
Note that for mixed-language programming using the
@code{ISO_C_BINDING} feature, there is a @code{C_BOOL} kind that can
......@@ -1067,7 +1140,7 @@ extensions.
@cindex extensions, implemented
GNU Fortran implements a number of extensions over standard
Fortran. This chapter contains information on their syntax and
Fortran. This chapter contains information on their syntax and
meaning. There are currently two categories of GNU Fortran
extensions, those that provide functionality beyond that provided
by any standard, and those that are supported by GNU Fortran
......@@ -1101,7 +1174,7 @@ without warning.
@subsection Old-style kind specifications
@cindex kind, old-style
GNU Fortran allows old-style kind specifications in declarations. These
GNU Fortran allows old-style kind specifications in declarations. These
look like:
@smallexample
TYPESPEC*size x,y,z
......@@ -1182,7 +1255,7 @@ $END
It should be noted that the default terminator is @samp{/} rather than
@samp{&END}.
Querying of the namelist when inputting from stdin. After at least
Querying of the namelist when inputting from stdin. After at least
one space, entering @samp{?} sends to stdout the namelist name and the names of
the variables in the namelist:
@smallexample
......@@ -1282,15 +1355,15 @@ of the @code{READ} statement, and the output item lists of the
@cindex BOZ literal constants
Besides decimal constants, Fortran also supports binary (@code{b}),
octal (@code{o}) and hexadecimal (@code{z}) integer constants. The
octal (@code{o}) and hexadecimal (@code{z}) integer constants. The
syntax is: @samp{prefix quote digits quote}, were the prefix is
either @code{b}, @code{o} or @code{z}, quote is either @code{'} or
@code{"} and the digits are for binary @code{0} or @code{1}, for
octal between @code{0} and @code{7}, and for hexadecimal between
@code{0} and @code{F}. (Example: @code{b'01011101'}.)
@code{0} and @code{F}. (Example: @code{b'01011101'}.)
Up to Fortran 95, BOZ literals were only allowed to initialize
integer variables in DATA statements. Since Fortran 2003 BOZ literals
integer variables in DATA statements. Since Fortran 2003 BOZ literals
are also allowed as argument of @code{REAL}, @code{DBLE}, @code{INT}
and @code{CMPLX}; the result is the same as if the integer BOZ
literal had been converted by @code{TRANSFER} to, respectively,
......@@ -1300,7 +1373,7 @@ As GNU Fortran extension the intrinsic procedures @code{FLOAT},
As an extension, GNU Fortran allows hexadecimal BOZ literal constants to
be specified using the @code{X} prefix, in addition to the standard
@code{Z} prefix. The BOZ literal can also be specified by adding a
@code{Z} prefix. The BOZ literal can also be specified by adding a
suffix to the string, for example, @code{Z'ABC'} and @code{'ABC'Z} are
equivalent.
......@@ -1310,7 +1383,7 @@ In DATA statements, in direct assignments, where the right-hand side
only contains a BOZ literal constant, and for old-style initializers of
the form @code{integer i /o'0173'/}, the constant is transferred
as if @code{TRANSFER} had been used; for @code{COMPLEX} numbers, only
the real part is initialized unless @code{CMPLX} is used. In all other
the real part is initialized unless @code{CMPLX} is used. In all other
cases, the BOZ literal constant is converted to an @code{INTEGER} value with
the largest decimal representation. This value is then converted
numerically to the type and kind of the variable in question.
......@@ -1494,10 +1567,10 @@ example:
ipt = loc(target)
@end smallexample
As long as @code{ipt} remains unchanged, @code{iarr} is now an alias for
@code{target}. The optimizer, however, will not detect this aliasing, so
@code{target}. The optimizer, however, will not detect this aliasing, so
it is unsafe to use @code{iarr} and @code{target} simultaneously. Using
a pointee in any way that violates the Fortran aliasing rules or
assumptions is illegal. It is the user's responsibility to avoid doing
assumptions is illegal. It is the user's responsibility to avoid doing
this; the compiler works under the assumption that no such aliasing
occurs.
......@@ -1513,10 +1586,10 @@ will ``incorrectly'' optimize code with illegal aliasing.)
There are a number of restrictions on the attributes that can be applied
to Cray pointers and pointees. Pointees may not have the
@code{ALLOCATABLE}, @code{INTENT}, @code{OPTIONAL}, @code{DUMMY},
@code{TARGET}, @code{INTRINSIC}, or @code{POINTER} attributes. Pointers
@code{TARGET}, @code{INTRINSIC}, or @code{POINTER} attributes. Pointers
may not have the @code{DIMENSION}, @code{POINTER}, @code{TARGET},
@code{ALLOCATABLE}, @code{EXTERNAL}, or @code{INTRINSIC} attributes, nor
may they be function results. Pointees may not occur in more than one
may they be function results. Pointees may not occur in more than one
pointer statement. A pointee cannot be a pointer. Pointees cannot occur
in equivalence, common, or data statements.
......@@ -1610,7 +1683,7 @@ free-form source code; the @code{c$omp}, @code{*$omp} and @code{!$omp}
directives in fixed form; the @code{!$} conditional compilation sentinels
in free form; and the @code{c$}, @code{*$} and @code{!$} sentinels
in fixed form, @command{gfortran} needs to be invoked with the
@option{-fopenmp}. This also arranges for automatic linking of the
@option{-fopenmp}. This also arranges for automatic linking of the
GNU OpenMP runtime library @ref{Top,,libgomp,libgomp,GNU OpenMP
runtime library}.
......@@ -1636,16 +1709,16 @@ Please note:
@itemize
@item
@option{-fopenmp} implies @option{-frecursive}, i.e., all local arrays
will be allocated on the stack. When porting existing code to OpenMP,
will be allocated on the stack. When porting existing code to OpenMP,
this may lead to surprising results, especially to segmentation faults
if the stacksize is limited.
@item
On glibc-based systems, OpenMP enabled applications cannot be statically
linked due to limitations of the underlying pthreads-implementation. It
linked due to limitations of the underlying pthreads-implementation. It
might be possible to get a working solution if
@command{-Wl,--whole-archive -lpthread -Wl,--no-whole-archive} is added
to the command line. However, this is not supported by @command{gcc} and
to the command line. However, this is not supported by @command{gcc} and
thus not recommended.
@end itemize
......@@ -1660,9 +1733,9 @@ GNU Fortran supports argument list functions @code{%VAL}, @code{%REF}
and @code{%LOC} statements, for backward compatibility with g77.
It is recommended that these should be used only for code that is
accessing facilities outside of GNU Fortran, such as operating system
or windowing facilities. It is best to constrain such uses to isolated
or windowing facilities. It is best to constrain such uses to isolated
portions of a program--portions that deal specifically and exclusively
with low-level, system-dependent facilities. Such portions might well
with low-level, system-dependent facilities. Such portions might well
provide a portable interface for use by the program as a whole, but are
themselves not portable, and should be thoroughly tested each time they
are rebuilt using a new compiler or version of a compiler.
......@@ -1731,7 +1804,7 @@ code that uses them running with the GNU Fortran compiler.
Structures are user-defined aggregate data types; this functionality was
standardized in Fortran 90 with an different syntax, under the name of
``derived types''. Here is an example of code using the non portable
``derived types''. Here is an example of code using the non portable
structure syntax:
@example
......@@ -1809,7 +1882,7 @@ GNU Fortran doesn't support the @code{ENCODE} and @code{DECODE}
statements. These statements are best replaced by @code{READ} and
@code{WRITE} statements involving internal files (@code{CHARACTER}
variables and arrays), which have been part of the Fortran standard since
Fortran 77. For example, replace a code fragment like
Fortran 77. For example, replace a code fragment like
@smallexample
INTEGER*1 LINE(80)
......@@ -1857,10 +1930,10 @@ c ... Code that sets A, B and C
@cindex @code{FORMAT}
A variable @code{FORMAT} expression is format statement which includes
angle brackets enclosing a Fortran expression: @code{FORMAT(I<N>)}. GNU
Fortran does not support this legacy extension. The effect of variable
angle brackets enclosing a Fortran expression: @code{FORMAT(I<N>)}. GNU
Fortran does not support this legacy extension. The effect of variable
format expressions can be reproduced by using the more powerful (and
standard) combination of internal output and string formats. For example,
standard) combination of internal output and string formats. For example,
replace a code fragment like this:
@smallexample
......@@ -1901,8 +1974,8 @@ c
Some Fortran compilers, including @command{g77}, let the user declare
complex functions with the syntax @code{COMPLEX FUNCTION name*16()}, as
well as @code{COMPLEX*16 FUNCTION name()}. Both are non-standard, legacy
extensions. @command{gfortran} accepts the latter form, which is more
well as @code{COMPLEX*16 FUNCTION name()}. Both are non-standard, legacy
extensions. @command{gfortran} accepts the latter form, which is more
common, but not the former.
......@@ -1923,7 +1996,7 @@ common, but not the former.
@end menu
This chapter is about mixed-language interoperability, but also applies
if one links Fortran code compiled by different compilers. In most cases,
if one links Fortran code compiled by different compilers. In most cases,
use of the C Binding features of the Fortran 2003 standard is sufficient,
and their use is highly recommended.
......@@ -1943,18 +2016,18 @@ and their use is highly recommended.
Since Fortran 2003 (ISO/IEC 1539-1:2004(E)) there is a
standardized way to generate procedure and derived-type
declarations and global variables which are interoperable with C
(ISO/IEC 9899:1999). The @code{bind(C)} attribute has been added
(ISO/IEC 9899:1999). The @code{bind(C)} attribute has been added
to inform the compiler that a symbol shall be interoperable with C;
also, some constraints are added. Note, however, that not
all C features have a Fortran equivalent or vice versa. For instance,
also, some constraints are added. Note, however, that not
all C features have a Fortran equivalent or vice versa. For instance,
neither C's unsigned integers nor C's functions with variable number
of arguments have an equivalent in Fortran.
Note that array dimensions are reversely ordered in C and that arrays in
C always start with index 0 while in Fortran they start by default with
1. Thus, an array declaration @code{A(n,m)} in Fortran matches
1. Thus, an array declaration @code{A(n,m)} in Fortran matches
@code{A[m][n]} in C and accessing the element @code{A(i,j)} matches
@code{A[j-1][i-1]}. The element following @code{A(i,j)} (C: @code{A[j-1][i-1]};
@code{A[j-1][i-1]}. The element following @code{A(i,j)} (C: @code{A[j-1][i-1]};
assuming @math{i < n}) in memory is @code{A(i+1,j)} (C: @code{A[j-1][i]}).
@node Intrinsic Types
......@@ -1962,15 +2035,15 @@ assuming @math{i < n}) in memory is @code{A(i+1,j)} (C: @code{A[j-1][i]}).
In order to ensure that exactly the same variable type and kind is used
in C and Fortran, the named constants shall be used which are defined in the
@code{ISO_C_BINDING} intrinsic module. That module contains named constants
@code{ISO_C_BINDING} intrinsic module. That module contains named constants
for kind parameters and character named constants for the escape sequences
in C. For a list of the constants, see @ref{ISO_C_BINDING}.
in C. For a list of the constants, see @ref{ISO_C_BINDING}.
@node Derived Types and struct
@subsection Derived Types and struct
For compatibility of derived types with @code{struct}, one needs to use
the @code{BIND(C)} attribute in the type declaration. For instance, the
the @code{BIND(C)} attribute in the type declaration. For instance, the
following type declaration
@smallexample
......@@ -1999,8 +2072,8 @@ matches the following @code{struct} declaration in C
Derived types with the C binding attribute shall not have the @code{sequence}
attribute, type parameters, the @code{extends} attribute, nor type-bound
procedures. Every component must be of interoperable type and kind and may not
have the @code{pointer} or @code{allocatable} attribute. The names of the
procedures. Every component must be of interoperable type and kind and may not
have the @code{pointer} or @code{allocatable} attribute. The names of the
variables are irrelevant for interoperability.
As there exist no direct Fortran equivalents, neither unions nor structs
......@@ -2010,7 +2083,7 @@ with bit field or variable-length array members are interoperable.
@subsection Interoperable Global Variables
Variables can be made accessible from C using the C binding attribute,
optionally together with specifying a binding name. Those variables
optionally together with specifying a binding name. Those variables
have to be declared in the declaration part of a @code{MODULE},
be of interoperable type, and have neither the @code{pointer} nor
the @code{allocatable} attribute.
......@@ -2026,22 +2099,22 @@ the @code{allocatable} attribute.
Here, @code{_MyProject_flags} is the case-sensitive name of the variable
as seen from C programs while @code{global_flag} is the case-insensitive
name as seen from Fortran. If no binding name is specified, as for
name as seen from Fortran. If no binding name is specified, as for
@var{tp}, the C binding name is the (lowercase) Fortran binding name.
If a binding name is specified, only a single variable may be after the
double colon. Note of warning: You cannot use a global variable to
double colon. Note of warning: You cannot use a global variable to
access @var{errno} of the C library as the C standard allows it to be
a macro. Use the @code{IERRNO} intrinsic (GNU extension) instead.
a macro. Use the @code{IERRNO} intrinsic (GNU extension) instead.
@node Interoperable Subroutines and Functions
@subsection Interoperable Subroutines and Functions
Subroutines and functions have to have the @code{BIND(C)} attribute to
be compatible with C. The dummy argument declaration is relatively
straightforward. However, one needs to be careful because C uses
be compatible with C. The dummy argument declaration is relatively
straightforward. However, one needs to be careful because C uses
call-by-value by default while Fortran behaves usually similar to
call-by-reference. Furthermore, strings and pointers are handled
differently. Note that only explicit size and assumed-size arrays are
call-by-reference. Furthermore, strings and pointers are handled
differently. Note that only explicit size and assumed-size arrays are
supported but not assumed-shape or allocatable arrays.
To pass a variable by value, use the @code{VALUE} attribute.
......@@ -2063,10 +2136,10 @@ matches the Fortran declaration
Note that pointer arguments also frequently need the @code{VALUE} attribute,
see @ref{Working with Pointers}.
Strings are handled quite differently in C and Fortran. In C a string
Strings are handled quite differently in C and Fortran. In C a string
is a @code{NUL}-terminated array of characters while in Fortran each string
has a length associated with it and is thus not terminated (by e.g.
@code{NUL}). For example, if one wants to use the following C function,
@code{NUL}). For example, if one wants to use the following C function,
@smallexample
#include <stdio.h>
......@@ -2090,13 +2163,13 @@ to print ``Hello World'' from Fortran, one can call it using
@end smallexample
As the example shows, one needs to ensure that the
string is @code{NUL} terminated. Additionally, the dummy argument
string is @code{NUL} terminated. Additionally, the dummy argument
@var{string} of @code{print_C} is a length-one assumed-size
array; using @code{character(len=*)} is not allowed. The example
array; using @code{character(len=*)} is not allowed. The example
above uses @code{c_char_"Hello World"} to ensure the string
literal has the right type; typically the default character
kind and @code{c_char} are the same and thus @code{"Hello World"}
is equivalent. However, the standard does not guarantee this.
is equivalent. However, the standard does not guarantee this.
The use of strings is now further illustrated using the C library
function @code{strncpy}, whose prototype is
......@@ -2106,7 +2179,7 @@ function @code{strncpy}, whose prototype is
@end smallexample
The function @code{strncpy} copies at most @var{n} characters from
string @var{s2} to @var{s1} and returns @var{s1}. In the following
string @var{s2} to @var{s1} and returns @var{s1}. In the following
example, we ignore the return value:
@smallexample
......@@ -2136,7 +2209,7 @@ The intrinsic procedures are described in @ref{Intrinsic Procedures}.
@subsection Working with Pointers
C pointers are represented in Fortran via the special opaque derived type
@code{type(c_ptr)} (with private components). Thus one needs to
@code{type(c_ptr)} (with private components). Thus one needs to
use intrinsic conversion procedures to convert from or to C pointers.
For example,
......@@ -2284,16 +2357,16 @@ END MODULE m
@subsection Further Interoperability of Fortran with C
Assumed-shape and allocatable arrays are passed using an array descriptor
(dope vector). The internal structure of the array descriptor used
by GNU Fortran is not yet documented and will change. There will also be
(dope vector). The internal structure of the array descriptor used
by GNU Fortran is not yet documented and will change. There will also be
a Technical Report (TR 29113) which standardizes an interoperable
array descriptor. Until then, you can use the Chasm Language
array descriptor. Until then, you can use the Chasm Language
Interoperability Tools, @url{http://chasm-interop.sourceforge.net/},
which provide an interface to GNU Fortran's array descriptor.
The technical report 29113 will presumably also include support for
C-interoperable @code{OPTIONAL} and for assumed-rank and assumed-type
dummy arguments. However, the TR has neither been approved nor implemented
dummy arguments. However, the TR has neither been approved nor implemented
in GNU Fortran; therefore, these features are not yet available.
......@@ -2302,10 +2375,10 @@ in GNU Fortran; therefore, these features are not yet available.
@section GNU Fortran Compiler Directives
The Fortran standard standard describes how a conforming program shall
behave; however, the exact implementation is not standardized. In order
behave; however, the exact implementation is not standardized. In order
to allow the user to choose specific implementation details, compiler
directives can be used to set attributes of variables and procedures
which are not part of the standard. Whether a given attribute is
which are not part of the standard. Whether a given attribute is
supported and its exact effects depend on both the operating system and
on the processor; see
@ref{Top,,C Extensions,gcc,Using the GNU Compiler Collection (GCC)}
......@@ -2323,13 +2396,13 @@ instead using the stack
Besides changing the calling convention, the attributes also influence
the decoration of the symbol name, e.g., by a leading underscore or by
a trailing at-sign followed by the number of bytes on the stack. When
a trailing at-sign followed by the number of bytes on the stack. When
assigning a procedure to a procedure pointer, both should use the same
calling convention.
On some systems, procedures and global variables (module variables and
@code{COMMON} blocks) need special handling to be accessible when they
are in a shared library. The following attributes are available:
are in a shared library. The following attributes are available:
@itemize
@item @code{DLLEXPORT} -- provide a global pointer to a pointer in the DLL
......@@ -2364,14 +2437,14 @@ the same declaration part as the variable or procedure pointer.
Even if you are doing mixed-language programming, it is very
likely that you do not need to know or use the information in this
section. Since it is about the internal structure of GNU Fortran,
section. Since it is about the internal structure of GNU Fortran,
it may also change in GCC minor releases.
When you compile a @code{PROGRAM} with GNU Fortran, a function
with the name @code{main} (in the symbol table of the object file)
is generated, which initializes the libgfortran library and then
calls the actual program which uses the name @code{MAIN__}, for
historic reasons. If you link GNU Fortran compiled procedures
historic reasons. If you link GNU Fortran compiled procedures
to, e.g., a C or C++ program or to a Fortran program compiled by
a different compiler, the libgfortran library is not initialized
and thus a few intrinsic procedures do not work properly, e.g.
......@@ -2380,16 +2453,16 @@ those for obtaining the command-line arguments.
Therefore, if your @code{PROGRAM} is not compiled with
GNU Fortran and the GNU Fortran compiled procedures require
intrinsics relying on the library initialization, you need to
initialize the library yourself. Using the default options,
initialize the library yourself. Using the default options,
gfortran calls @code{_gfortran_set_args} and
@code{_gfortran_set_options}. The initialization of the former
@code{_gfortran_set_options}. The initialization of the former
is needed if the called procedures access the command line
(and for backtracing); the latter sets some flags based on the
standard chosen or to enable backtracing. In typical programs,
standard chosen or to enable backtracing. In typical programs,
it is not necessary to call any initialization function.
If your @code{PROGRAM} is compiled with GNU Fortran, you shall
not call any of the following functions. The libgfortran
not call any of the following functions. The libgfortran
initialization functions are shown in C syntax but using C
bindings they are also accessible from Fortran.
......@@ -2403,7 +2476,7 @@ bindings they are also accessible from Fortran.
@item @emph{Description}:
@code{_gfortran_set_args} saves the command-line arguments; this
initialization is required if any of the command-line intrinsics
is called. Additionally, it shall be called if backtracing is
is called. Additionally, it shall be called if backtracing is
enabled (see @code{_gfortran_set_options}).
@item @emph{Syntax}:
......@@ -2437,10 +2510,10 @@ int main (int argc, char *argv[])
@item @emph{Description}:
@code{_gfortran_set_options} sets several flags related to the Fortran
standard to be used, whether backtracing or core dumps should be enabled
and whether range checks should be performed. The syntax allows for
and whether range checks should be performed. The syntax allows for
upward compatibility since the number of passed flags is specified; for
non-passed flags, the default value is used. See also
@pxref{Code Gen Options}. Please note that not all flags are actually
non-passed flags, the default value is used. See also
@pxref{Code Gen Options}. Please note that not all flags are actually
used.
@item @emph{Syntax}:
......@@ -2464,23 +2537,23 @@ Possible values are (bitwise or-ed) @code{GFC_STD_F77} (1),
| GFC_STD_F95_DEL | GFC_STD_F95 | GFC_STD_F2003 | GFC_STD_F2008
| GFC_STD_F2008_OBS | GFC_STD_F77 | GFC_STD_GNU | GFC_STD_LEGACY}.
@item @var{option}[1] @tab Standard-warning flag; prints a warning to
standard error. Default: @code{GFC_STD_F95_DEL | GFC_STD_LEGACY}.
standard error. Default: @code{GFC_STD_F95_DEL | GFC_STD_LEGACY}.
@item @var{option}[2] @tab If non zero, enable pedantic checking.
Default: off.
@item @var{option}[3] @tab If non zero, enable core dumps on run-time
errors. Default: off.
errors. Default: off.
@item @var{option}[4] @tab If non zero, enable backtracing on run-time
errors. Default: off.
errors. Default: off.
Note: Installs a signal handler and requires command-line
initialization using @code{_gfortran_set_args}.
@item @var{option}[5] @tab If non zero, supports signed zeros.
Default: enabled.
@item @var{option}[6] @tab Enables run-time checking. Possible values
@item @var{option}[6] @tab Enables run-time checking. Possible values
are (bitwise or-ed): GFC_RTCHECK_BOUNDS (1), GFC_RTCHECK_ARRAY_TEMPS (2),
GFC_RTCHECK_RECURSION (4), GFC_RTCHECK_DO (16), GFC_RTCHECK_POINTER (32).
Default: disabled.
@item @var{option}[7] @tab If non zero, range checking is enabled.
Default: enabled. See -frange-check (@pxref{Code Gen Options}).
Default: enabled. See -frange-check (@pxref{Code Gen Options}).
@end multitable
@item @emph{Example}:
......@@ -2541,7 +2614,7 @@ for unformatted files.
@item @emph{Arguments}:
@multitable @columnfractions .15 .70
@item @var{val} @tab Length of the record marker; valid values
are 4 and 8. Default is 4.
are 4 and 8. Default is 4.
@end multitable
@item @emph{Example}:
......@@ -2565,7 +2638,7 @@ int main (int argc, char *argv[])
@table @asis
@item @emph{Description}:
@code{_gfortran_set_fpe} sets the IEEE exceptions for which a
Floating Point Exception (FPE) should be raised. On most systems,
Floating Point Exception (FPE) should be raised. On most systems,
this will result in a SIGFPE signal being sent and the program
being interrupted.
......@@ -2574,7 +2647,7 @@ being interrupted.
@item @emph{Arguments}:
@multitable @columnfractions .15 .70
@item @var{option}[0] @tab IEEE exceptions. Possible values are
@item @var{option}[0] @tab IEEE exceptions. Possible values are
(bitwise or-ed) zero (0, default) no trapping,
@code{GFC_FPE_INVALID} (1), @code{GFC_FPE_DENORMAL} (2),
@code{GFC_FPE_ZERO} (4), @code{GFC_FPE_OVERFLOW} (8),
......@@ -2603,7 +2676,7 @@ int main (int argc, char *argv[])
@table @asis
@item @emph{Description}:
@code{_gfortran_set_max_subrecord_length} set the maximum length
for a subrecord. This option only makes sense for testing and
for a subrecord. This option only makes sense for testing and
debugging of unformatted I/O.
@item @emph{Syntax}:
......@@ -2755,8 +2828,8 @@ keep code private on request.
@item Bug hunting/squishing
Find bugs and write more test cases! Test cases are especially very
welcome, because it allows us to concentrate on fixing bugs instead of
isolating them. Going through the bugzilla database at
@url{http://gcc.gnu.org/bugzilla/} to reduce testcases posted there and
isolating them. Going through the bugzilla database at
@url{http://gcc.gnu.org/@/bugzilla/} to reduce testcases posted there and
add more information (for example, for which version does the testcase
work, for which versions does it fail?) is also very helpful.
......@@ -2876,7 +2949,7 @@ Environment variable forcing standard output to be line buffered (unix).
@node Option Index
@unnumbered Option Index
@command{gfortran}'s command line options are indexed here without any
initial @samp{-} or @samp{--}. Where an option has both positive and
initial @samp{-} or @samp{--}. Where an option has both positive and
negative forms (such as -foption and -fno-option), relevant entries in
the manual are indexed under the most appropriate form; it may sometimes
be useful to look up both forms.
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment