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Document changes to CONVERT for -mabi-ieeelongdouble for POWER.

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gcc/fortran/ChangeLog:

	* gfortran.texi: Mention r16_ieee and r16_ibm.
	* invoke.texi: Likewise.
This commit is contained in:
Thomas Koenig 2022-04-28 18:23:16 +02:00
parent d993c6dea7
commit 1a5ae012ff
2 changed files with 39 additions and 9 deletions
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30
gcc/fortran/gfortran.texi
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@ -589,7 +589,7 @@ Malformed environment variables are silently ignored.
* GFORTRAN_SHOW_LOCUS:: Show location for runtime errors
* GFORTRAN_OPTIONAL_PLUS:: Print leading + where permitted
* GFORTRAN_LIST_SEPARATOR:: Separator for list output
* GFORTRAN_CONVERT_UNIT:: Set endianness for unformatted I/O
* GFORTRAN_CONVERT_UNIT:: Set conversion for unformatted I/O
* GFORTRAN_ERROR_BACKTRACE:: Show backtrace on run-time errors
* GFORTRAN_FORMATTED_BUFFER_SIZE:: Buffer size for formatted files
* GFORTRAN_UNFORMATTED_BUFFER_SIZE:: Buffer size for unformatted files
@ -686,11 +686,12 @@ when @command{a.out} is the compiled Fortran program that you want to run.
Default is a single space.
@node GFORTRAN_CONVERT_UNIT
@section @env{GFORTRAN_CONVERT_UNIT}---Set endianness for unformatted I/O
@section @env{GFORTRAN_CONVERT_UNIT}---Set conversion for unformatted I/O
By setting the @env{GFORTRAN_CONVERT_UNIT} variable, it is possible
to change the representation of data for unformatted files.
The syntax for the @env{GFORTRAN_CONVERT_UNIT} variable is:
The syntax for the @env{GFORTRAN_CONVERT_UNIT} variable for
most systems is:
@smallexample
GFORTRAN_CONVERT_UNIT: mode | mode ';' exception | exception ;
mode: 'native' | 'swap' | 'big_endian' | 'little_endian' ;
@ -711,14 +712,24 @@ the modes are the same as for the @code{CONVERT} specifier:
for unformatted files.
@item @code{BIG_ENDIAN} Use the big-endian format for unformatted files.
@end itemize
For POWER systems which support @option{-mabi=ieeelongdouble},
there are additional options, which can be combined with the
others with commas. Those are
@itemize @w{}
@item @code{R16_IEEE} Use IEEE 128-bit format for @code{REAL(KIND=16)}.
@item @code{R16_IBM} Use IBM @code{long double} format for
@code{REAL(KIND=16)}.
@end itemize
A missing mode for an exception is taken to mean @code{BIG_ENDIAN}.
Examples of values for @env{GFORTRAN_CONVERT_UNIT} are:
@itemize @w{}
@item @code{'big_endian'} Do all unformatted I/O in big_endian mode.
@item @code{'big_endian'} Do all unformatted I/O in big_endian mod.e
@item @code{'little_endian;native:10-20,25'} Do all unformatted I/O
in little_endian mode, except for units 10 to 20 and 25, which are in
native format.
@item @code{'10-20'} Units 10 to 20 are big-endian, the rest is native.
@item @code{'big_endian,r16_ibm'} Do all unformatted I/O in big-endian
mode and use IBM long double for output of @code{REAL(KIND=16)} values.
@end itemize
Setting the environment variables should be done on the command
@ -1736,7 +1747,7 @@ the @code{CONVERT} specifier on the @code{OPEN} statement.
@xref{GFORTRAN_CONVERT_UNIT}, for an alternative way of specifying
the data format via an environment variable.
Valid values for @code{CONVERT} are:
Valid values for @code{CONVERT} on most systems are:
@itemize @w{}
@item @code{CONVERT='NATIVE'} Use the native format. This is the default.
@item @code{CONVERT='SWAP'} Swap between little- and big-endian.
@ -1745,6 +1756,15 @@ for unformatted files.
@item @code{CONVERT='BIG_ENDIAN'} Use the big-endian representation for
unformatted files.
@end itemize
On POWER systems which support @option{-mabi=ieeelongdouble},
there are additional options, which can be combined with the others
with commas. Those are
@itemize @w{}
@item @code{CONVERT='R16_IEEE'} Use IEEE 128-bit format for
@code{REAL(KIND=16)}.
@item @code{CONVERT='R16_IBM'} Use IBM @code{long double} format for
real@code{REAL(KIND=16)}.
@end itemize
Using the option could look like this:
@smallexample

18
gcc/fortran/invoke.texi
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@ -1435,10 +1435,20 @@ These options affect the runtime behavior of programs compiled with GNU Fortran.
@item -fconvert=@var{conversion}
@opindex @code{fconvert=}@var{conversion}
Specify the representation of data for unformatted files. Valid
values for conversion are: @samp{native}, the default; @samp{swap},
swap between big- and little-endian; @samp{big-endian}, use big-endian
representation for unformatted files; @samp{little-endian}, use little-endian
representation for unformatted files.
values for conversion on most systems are: @samp{native}, the default;
@samp{swap}, swap between big- and little-endian; @samp{big-endian}, use
big-endian representation for unformatted files; @samp{little-endian}, use
little-endian representation for unformatted files.
On POWER systems which suppport @option{-mabi=ieeelongdouble},
there are additional options, which can be combined with others with
commas. Those are
@itemize @w{}
@item @option{-fconvert=r16_ieee} Use IEEE 128-bit format for
@code{REAL(KIND=16)}.
@item @option{-fconvert=r16_ibm} Use IBM long double format for
@code{REAL(KIND=16)}.
@end itemize
@emph{This option has an effect only when used in the main program.
The @code{CONVERT} specifier and the GFORTRAN_CONVERT_UNIT environment