On 8/11/23 5:34 AM, Jorge D'Elia via Fortran wrote:
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)...
Regardless, we should never segfault. Thanks for the code example. We need to get a bug report opened on this. I am on travel this morning, but if I have time i will do so this afternnon if someone else does not beat me to it.
There were some recent patches in this area IIRC. Jerry
