Fortran functions for checking Inf/NaN. They should work even if the compilers are invoked with aggressive optimization flags such as `gfortran -Ofast`.
License: GNU Lesser General Public License v3.0
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gtest fails if gfortran-13 is invoked with -Ofast -flto, which runs the standard link-time optimizer.
On Kunpeng Platform with Ubuntu 18.04 Linux 4.15.0-166-generic, is_nan fails to identify NaN when compiled with gfortran-8 -O3 -ffast-math -Ofast -flto (ieee_is_nan does not work either).
The details are as follows.
$ lscpu
Architecture: aarch64
Byte Order: Little Endian
CPU(s): 2
On-line CPU(s) list: 0,1
Thread(s) per core: 1
Core(s) per socket: 2
Socket(s): 1
NUMA node(s): 1
Vendor ID: 0x48
Model: 0
Stepping: 0x1
BogoMIPS: 200.00
L1d cache: 64K
L1i cache: 64K
L2 cache: 512K
L3 cache: 32768K
NUMA node0 CPU(s): 0,1
Flags: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm jscvt fcma dcpop asimddp asimdfhm
$ uname -a
Linux kunpeng-0001 4.15.0-166-generic #174-Ubuntu SMP Wed Dec 8 19:08:37 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux
$ gfortran --version
GNU Fortran (Ubuntu/Linaro 8.4.0-1ubuntu1~18.04) 8.4.0
Copyright (C) 2018 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.
$ cd test && make clean && make gtest
rm -f *.o *.mod *.dbg *test
gfortran -O3 -ffast-math -Ofast -flto -o gtest ../consts.f90 ../infnan.f90 ieee_infnan.f90 testinfnan.f90 test.f90
./gtest
Single-precision tests:
IS_NAN: F F F F F F F F F F F F F F F F F F F
IEEE_IS_NAN: F F F F F F F F F F F F F F F F F F F
Some tests failed. The data is
Infinity -Inf NaN NaN 4.E+01 -4.E+01 0.E+00 -0.E+00 0.E+00 -0.E+00 3.E+38 -3.E+38 1.E-07 -1.E-07 1.E-38 -1.E-38 0.E+00 1.E+00 -1.E+00
Double-precision tests:
IS_NAN: F F F F F F F F F F F F F F F F F F F
IEEE_IS_NAN: F F F F F F F F F F F F F F F F F F F
Some tests failed. The data is
Infinity -Inf NaN NaN 4.D+01 -4.D+01 1.D+00 -1.D+00 0.D+00 -0.D+00 2.+308 -2.+308 2.D-16 -2.D-16 2.-308 -2.-308 0.D+00 1.D+00 -1.D+00
Note: The following floating-point exceptions are signalling: IEEE_INVALID_FLAG IEEE_OVERFLOW_FLAG
STOP 1
Makefile:65: recipe for target 'gtest' failed
make: *** [gtest] Error 1
I suggest adding the topics floating-point, fortran, numerical in the About section.
I suggest adding the topic nan in the About section.
$ uname -a
Linux 5.15.0-56-generic #62-Ubuntu SMP Tue Nov 22 19:54:14 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
$ flang --version
flang version 15.0.3
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/zaikunzhang/local/flang/bin
$flang -O3 -Ofast -ffast-math -o ftest ../consts.f90 ../infnan.f90 ieee_infnan.f90 testinfnan.f90 test.f90
$./ftest
Single-precision tests:
IS_NAN: F F F F F F F F F F F F F F F F F F F
IEEE_IS_NAN: F F T T F F F F F F F F F F F F F F F
Some tests failed. The data is
Inf -Inf NaN NaN 1.E+00 -1.E+00 0.E+00 -0.E+00 0.E+00 -0.E+00 3.E+38 -3.E+38 1.E-07 -1.E-07 1.E-38 -1.E-38 0.E+00 1.E+00 -1.E+00
Double-precision tests:
IS_NAN: F F F F F F F F F F F F F F F F F F F
IEEE_IS_NAN: F F T T F F F F F F F F F F F F F F F
Some tests failed. The data is
Inf -Inf NaN NaN 1.D+00 -1.D+00 0.D+00 -0.D+00 0.D+00 -0.D+00 2.+308 -2.+308 2.D-16 -2.D-16 2.-308 -2.-308 0.D+00 1.D+00 -1.D+00
Warning: ieee_invalid is signaling
Warning: ieee_inexact is signaling
is_nan does not work with ifx -fast, the version of ifx being ifx (IFORT) 2022.1.0 20220316. The system is Ubuntu 20.04.
Here is the error information.
cd test && ifx -fast -o xtest ../consts.f90 ../infnan.f90 ieee_infnan.f90 testinfnan.f90 test.f90 && ./xtest
Single-precision tests:
IS_NAN: F F F F F F F F F F F F F F F F F F F
IEEE_IS_NAN: F F T T F F F F F F F F F F F F F F F
Some tests failed. The data is
Infinity -Inf NaN NaN 1.E+00 -1.E+00 1.E-38 -1.E-38 0.E+00 0.E+00 3.E+38 -3.E+38 1.E-07 -1.E-07 1.E-38 -1.E-38 0.E+00 1.E+00 -1.E+00
Double-precision tests:
IS_NAN: F F F F F F F F F F F F F F F F F F F
IEEE_IS_NAN: F F T T F F F F F F F F F F F F F F F
Some tests failed. The data is
Infinity -Inf NaN NaN 1.D+00 -1.D+00 2.-308 -2.-308 0.D+00 0.D+00 2.+308 -2.+308 2.D-16 -2.D-16 2.-308 -2.-308 0.D+00 1.D+00 -1.D+00
1
Note that ieee_is_nan works in this case.
See https://github.com/equipez/infnan/actions/runs/6105399848
All the functions will fail if gfortran-13 is invoked with
-Ofast
or
-O3 -ffast-math
However, -O3 or -ffast-math alone does not cause the problem.
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