[Bug fortran/53771] New: inconsistent padding long double: mixture of 96 and 128

[Bug fortran/53771] New: inconsistent padding long double: mixture of 96 and 128

[johnfchandler at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53771

             Bug #: 53771
           Summary: inconsistent padding long double: mixture of 96 and
                    128
    Classification: Unclassified
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: johnfchandler@gmail.com


Created attachment 27704
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27704
a sample program exhibiting the bug

Overriding the default padding of REAL*10 data with the -m128bit-long-double or
-m96bit-long-double option does not work consistently.  Some data items in I/O
are still padded to the default length instead of the desired length.  In the
sample program, the array written to fort.1 via implied-do follows the default
padding instead of obeying the override.

Command:
 gfortran -v -m96bit-long-double btest.f
Driving: gfortran -v -m96bit-long-double btest.f -lgfortranbegin -lgfortran -lm
-shared-libgcc
Using built-in specs.
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-libgcj-multifile
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk
--disable-dssi --disable-plugin
--with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre --with-cpu=generic
--host=x86_64-redhat-linux
Thread model: posix
gcc version 4.1.2 20080704 (Red Hat 4.1.2-52)
 /usr/libexec/gcc/x86_64-redhat-linux/4.1.2/f951 btest.f -ffixed-form -quiet
-dumpbase btest.f -m96bit-long-double -mtune=generic -auxbase btest -version -I
/usr/lib/gcc/x86_64-redhat-linux/4.1.2/finclude -o /tmp/ccfzauZo.s
GNU F95 version 4.1.2 20080704 (Red Hat 4.1.2-52) (x86_64-redhat-linux)
        compiled by GNU C version 4.1.2 20080704 (Red Hat 4.1.2-52).
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
 as -V -Qy -o /tmp/ccEWq1lI.o /tmp/ccfzauZo.s
GNU assembler version 2.17.50.0.6-20.el5 (x86_64-redhat-linux) using BFD
version 2.17.50.0.6-20.el5 20061020
 /usr/libexec/gcc/x86_64-redhat-linux/4.1.2/collect2 --eh-frame-hdr -m
elf_x86_64 --hash-style=gnu -dynamic-linker /lib64/ld-linux-x86-64.so.2
/usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../lib64/crt1.o
/usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../lib64/crti.o
/usr/lib/gcc/x86_64-redhat-linux/4.1.2/crtbegin.o
-L/usr/lib/gcc/x86_64-redhat-linux/4.1.2
-L/usr/lib/gcc/x86_64-redhat-linux/4.1.2
-L/usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../lib64 -L/lib/../lib64
-L/usr/lib/../lib64 /tmp/ccEWq1lI.o -lgfortranbegin -lgfortran -lm -lgcc_s
-lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-redhat-linux/4.1.2/crtend.o
/usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../lib64/crtn.o

[Bug fortran/53771] inconsistent padding long double: mixture of 96 and 128

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53771

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-06-25 20:22:14 UTC ---
-m96bit-long-double/-m128bit-long-double changes the C ABI which means things
can get messy if you don't compile everything (including libc) with those
options.

If you want to use REAL*16, upgrade the compiler and that has support for
REAL*16.

[Bug fortran/53771] inconsistent padding long double: mixture of 96 and 128

[john.chandler at alum dot mit.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53771

--- Comment #2 from john.chandler at alum dot mit.edu 2012-06-25 23:51:37 UTC ---
On Mon, Jun 25, 2012 at 4:22 PM, pinskia at gcc dot gnu.org
<gcc-bugzilla@gcc.gnu.org> wrote:
> If you want to use REAL*16, upgrade the compiler and that has support for
> REAL*16.

Can the compiler be installed privately by a user without admin
privileges on the system?  The staff here would not be willing to
upgrade in the near future.

[Bug fortran/53771] inconsistent padding long double: mixture of 96 and 128

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53771

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |burnus at gcc dot gnu.org

--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> 2012-06-26 12:37:41 UTC ---
(In reply to comment #2)
> > If you want to use REAL*16, upgrade the compiler and that has support for
> > REAL*16.

Namely: GCC 4.6 supports REAL*16, including all math intrinsics.

> Can the compiler be installed privately by a user without admin
> privileges on the system?  The staff here would not be willing to
> upgrade in the near future.

Yes, that possibly. You can simply install it into some directory and directly
call the installed compiler binary (though it is more convenient to put the
"bin" directory into the path). Only for calling the compiled program, you
should make sure that the libraries are found (on Linux/Unix: set the
LD_LIBRARY_PATH) - or you link statically or you set an "-Wl,-rpath".

For a quick guide to compiling GCC oneself and to some *unofficial* binaries,
see http://gcc.gnu.org/wiki/GFortranBinaries 

My guess is that you are on a Red Hat Enterprise Linux 5.x system. RHEL 5 also
contains a technical preview of a newer GCC (which can be installed in
parallel), unfortunately, it only has GCC 4.4 and not 4.6 (or newer).
Otherwise, that would have been alternative.