Hello,
I realised when I created the small code snippet I accidentally put the
variable "m" in the default integer declaration, I checked it and moving it
(to kind=16) does not make a difference either.
I also checked on Ubuntu-64, same GCC & GFortran version (9.3.0) and I get
the same error message / behaviour. I re-attach the corrected f90 file,
which also as a slightly improved loop exit condition.
Best wishes, Bernd
----
On Wed, 19 Aug 2020 at 15:22, Bernd Eggen <bernd.eg...@gmail.com> wrote:
> Hello,
>
> I've come across an internal compiler error (in GFortran), concerning the
> function NINT(), I attach a very simple source code that illustrates the
> error. Essentially I am working with 16-byte integers, and there seems no
> way to ensure that NINT() returns the correct precision integer. [I am
> also testing this on an Ubuntu-64 installation, see separate email.]
>
> I tried a number of things, to no avail:
>
>
> 1. m=nint(y) ! this gives at best an 8 byte integer return and or
> larger numbers is negative,
> 2. m=nint(y,i16) ! this is the attached version, which generates
> compiler error
> 3. m=nint(y,kind=i16) ! also generates error
> 4. integer(kind=16) :: nint; ... m=nint(y) ! does not change return
> type
> 5. trying to compile with "-fdefault-integer-16" # option does not
> exist
>
> Interestingly, in the related function, IDNINT() the "KIND" optional
> argument does not even seem to be implemented
>
> Please include all of the following items, the first three of which can be
> obtained from the output of gcc -v:
>
> - the exact version of GCC;
> - the system type; *(Cygwin 64 on top of Windows 10)*
> - the options given when GCC was configured/built;
>
> -> *cygcheck -c cygwin*
> Cygwin Package Information
> Package Version Status
> cygwin *3.1.6-1* OK
>
> -> gcc -v
> Using built-in specs.
> COLLECT_GCC=gcc
> COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-cygwin/9.3.0/lto-wrapper.exe
> Target: x86_64-pc-cygwin
> Configured with:
> /cygdrive/i/szsz/tmpp/gcc/gcc-9.3.0-2.x86_64/src/gcc-9.3.0/configure
> --srcdir=/cygdrive/i/szsz/tmpp/gcc/gcc-9.3.0-2.x86_64/src/gcc-9.3.0
> --prefix=/usr --exec-prefix=/usr --localstatedir=/var --sysconfdir=/etc
> --docdir=/usr/share/doc/gcc --htmldir=/usr/share/doc/gcc/html -C
> --build=x86_64-pc-cygwin --host=x86_64-pc-cygwin --target=x86_64-pc-cygwin
> --without-libiconv-prefix --without-libintl-prefix --libexecdir=/usr/lib
> --enable-shared --enable-shared-libgcc --enable-static
> --enable-version-specific-runtime-libs --enable-bootstrap
> --enable-__cxa_atexit --with-dwarf2 --with-tune=generic
> --enable-languages=c,c++,fortran,lto,objc,obj-c++ --enable-graphite
> --enable-threads=posix --enable-libatomic --enable-libgomp
> --enable-libquadmath --enable-libquadmath-support --disable-libssp
> --enable-libada --disable-symvers --with-gnu-ld --with-gnu-as
> --with-cloog-include=/usr/include/cloog-isl --without-libiconv-prefix
> --without-libintl-prefix --with-system-zlib --enable-linker-build-id
> --with-default-libstdcxx-abi=gcc4-compatible
> --enable-libstdcxx-filesystem-ts
> Thread model: posix
> gcc version 9.3.0 (GCC)
>
> and for Gfortran:
>
> -> gfortran --version
> GNU Fortran (GCC) *9.3.0*
> Copyright (C) 2019 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions. There
> is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
> PURPOSE.
>
> -> gfortran -v
> Using built-in specs.
> COLLECT_GCC=gfortran
> COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-cygwin/9.3.0/lto-wrapper.exe
> Target: x86_64-pc-cygwin
> Configured with:
> /cygdrive/i/szsz/tmpp/gcc/gcc-9.3.0-2.x86_64/src/gcc-9.3.0/configure
> --srcdir=/cygdrive/i/szsz/tmpp/gcc/gcc-9.3.0-2.x86_64/src/gcc-9.3.0
> --prefix=/usr --exec-prefix=/usr --localstatedir=/var --sysconfdir=/etc
> --docdir=/usr/share/doc/gcc --htmldir=/usr/share/doc/gcc/html -C
> --build=x86_64-pc-cygwin --host=x86_64-pc-cygwin --target=x86_64-pc-cygwin
> --without-libiconv-prefix --without-libintl-prefix --libexecdir=/usr/lib
> --enable-shared --enable-shared-libgcc --enable-static
> --enable-version-specific-runtime-libs --enable-bootstrap
> --enable-__cxa_atexit --with-dwarf2 --with-tune=generic
> --enable-languages=c,c++,fortran,lto,objc,obj-c++ --enable-graphite
> --enable-threads=posix --enable-libatomic --enable-libgomp
> --enable-libquadmath --enable-libquadmath-support --disable-libssp
> --enable-libada --disable-symvers --with-gnu-ld --with-gnu-as
> --with-cloog-include=/usr/include/cloog-isl --without-libiconv-prefix
> --without-libintl-prefix --with-system-zlib --enable-linker-build-id
> --with-default-libstdcxx-abi=gcc4-compatible
> --enable-libstdcxx-filesystem-ts
> Thread model: posix
> gcc version 9.3.0 (GCC)
>
>
> - the complete command line that triggers the bug; *see below*
> - the compiler output (error messages, warnings, etc.); *see below* and
> - the *preprocessed* file (*.i*) that triggers the bug, generated by
> adding -save-temps to the complete compilation command, or, in the
> case of a bug report for the GNAT front end, a complete set of source files
> (see below).
>
> -> gfortran -save-temps -o nint_error.e *nint_error.f90*
> nint_error.f90:17:0:
>
> 17 | m=nint(y,i16)
> |
> internal compiler error: in build_round_expr, at
> fortran/trans-intrinsic.c:396
> Please submit a full bug report,
> with preprocessed source if appropriate.
> See <https://gcc.gnu.org/bugs/> for instructions.
>
> (and with IDNINT()):
>
> -> gfortran -save-temps -o nint_error.e nint_error.f90
> nint_error.f90:17:7:
>
> 17 | m=idnint(y,i16)
> | 1
> Error: Too many arguments in call to ‘idnint’ at (1)
>
> Thanks for looking into this, Bernd (Eggen)
>
> PS Here a part of the output if omitting the "KIND" optional argument in
> NINT():
> -> ./nint_error.e | & more
>
> i16= 16
> 1 1 1.0000000000000000 0
> 2 2 2.0000000000000000 1
> 3 4 4.0000000000000000 3
> 4 8 8.0000000000000000 7
> [...]
> 31 1073741824 1073741824.0000000 1073741823
> 32 2147483648 2147483648.0000000 2147483647
> 33 4294967296 4294967296.0000000 *-1*
>
>
> As you can see, after 2^31-1 = 2147483647 it goes wrong and yields -1
>
> If increasing the integer by 1, it goes wrong thus:
>
> [...]
> 2147483647 2147483647.0000000 2147483647
> 2147483648 2147483648.0000000 -2147483648
> [...]
>
>
program nint_error
integer :: n
integer(kind=16) :: i, j, m, nint
integer, parameter :: idp=selected_real_kind(9,99)
integer, parameter :: i16=selected_int_kind(38)
real(kind=idp) :: x, y
write(*,'(*(g0:" "))') 'i16=', i16
i=1_16
x=1.0d0
do n=1, 128, 1
j=i-1_16
y=x-1.0d0
! m=nint(y,i16)
m=nint(y)
write(*,'(*(g0:" "))') n, i, x, m
i=i+i
x=x+x
if ( (n>3) .and. (m<1_16) ) exit
end do
stop
end program nint_error
