Dear GFortran developers,
With the beta gfortran 14.x.y versions we are noticing some runtime
errors in a production code.
One type of runtime errors is related to the concurrent use of the
intrinsic "repeat" when the source code is compiled with the
flag -march=native, please, see below:
$ cat test.f90
program test
implicit none
integer , parameter :: iin = kind (1)
integer (iin), parameter :: pp = 32
character (len=pp) :: cc
cc (1:pp) = repeat (" ",pp)
write (*,*)" cc : " // cc
end program test
$ gfortran --version
GNU Fortran (GCC) 14.0.0 20230808 (experimental)
Copyright (C) 2023 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.
a) Compiling with the flag -mtune=native only, without -march=native, the test
is ok:
$ gfortran -mtune=native -fcheck=all -std=f2018 -Wall -Werror -Wextra -Og -o
test.exe test.f90
$ test.exe
cc :
b) However, compiling with the flag -march=native:
$ gfortran -march=native -fcheck=all -std=f2018 -Wall -Werror -Wextra -Og -o
test.exe test.f90
$ test.exe
Program received signal SIGILL: Illegal instruction.
Backtrace for this error:
#0 0x14fae277fb1f in ???
#1 0x4011ad in ???
#2 0x401272 in ???
#3 0x14fae276a50f in ???
#4 0x14fae276a5c8 in ???
#5 0x4010c4 in ???
#6 0xffffffffffffffff in ???
Illegal instruction (core dumped)
On the other hand, compiling with the system version (GNU Fortran (GCC)
12.3.1 20230508 (Red Hat 12.3.1-1)) or replacing the intrinsic repeat
with:
do kk = 1, pp
cc (kk:kk) = " "
end do
both tests are ok. The error occurs on any of Intel or AMD computers,
e.g. in the present case:
$ lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Address sizes: 46 bits physical, 48 bits virtual
Byte Order: Little Endian
CPU(s): 6
On-line CPU(s) list: 0-5
Vendor ID: GenuineIntel
Model name: Intel(R) Core(TM) i7-3930K CPU @ 3.20GHz
CPU family: 6
Model: 45
Thread(s) per core: 1
Core(s) per socket: 6
Socket(s): 1
Stepping: 7
BogoMIPS: 6400.22
Caches (sum of all):
L1d: 192 KiB (6 instances)
L1i: 192 KiB (6 instances)
L2: 1.5 MiB (6 instances)
L3: 12 MiB (1 instance)
NUMA:
NUMA node(s): 1
NUMA node0 CPU(s): 0-5
By the way, I do not know if the -march=native flag or the intrinsic
repeat would be of deprecated use (or not)...
Regards.
Jorge.
--
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