Re: beta gfortran 14.x.y (using -march=native and intrinsic repeat) gives a signal SIGILL

[Jorge D'Elia <jdelia@intec.unl.edu.ar>]

Dear Paul / Jerry,

----- Mensaje original -----
> De: "Paul Richard Thomas" 
> Para: "Jerry D" 
> CC: "Jorge D'Elia" , "Gfortran List" , "Jorge D'Elia"
> 
> Enviado: Viernes, 11 de Agosto 2023 13:55:43
> Asunto: Re: beta gfortran 14.x.y (using -march=native and intrinsic repeat) gives a signal SIGILL
>
> I wonder why the development 14.0.0 doesn't exhibit this behaviour?
> 
> Could you please rerun with the compile options -g -fdump-tree-original .
> 
> The later should generate a file *.original with the content:
> 
> void test ()
> {
>  character(kind=1) cc[1:32];
> 
>  __builtin_memmove ((void *) &cc, (void *) &"
>       "[1]{lb: 1 sz: 1}, 32);
>  {
>    struct __st_parameter_dt dt_parm.0;
> 
>    dt_parm.0.common.filename = &"test_repeat.f90"[1]{lb: 1 sz: 1};
>    dt_parm.0.common.line = 7;
>    dt_parm.0.common.flags = 128;
>    dt_parm.0.common.unit = 6;
>    _gfortran_st_write (&dt_parm.0);
>    {
>      character(kind=1) str.1[38];
>      character(kind=1) str.2[41];
> 
>      _gfortran_concat_string (38, (character(kind=1)[1:] *) &str.1,
> 6, &" cc : "[1]{lb: 1 sz: 1}, 32, &cc);
>      _gfortran_concat_string (41, (character(kind=1)[1:] *) &str.2,
> 38, (character(kind=1)[1:] *) &str.1, 3, &"end"[1]{lb: 1 sz: 1});
>      _gfortran_transfer_character_write (&dt_parm.0,
> (character(kind=1)[1:] *) &str.2, 41);
>    }
>    _gfortran_st_write_done (&dt_parm.0);
>  }
> }
> 
> Note that repeat is reduced to the builtin memmove with 32 spaces going to cc.


Ok, then using:

$ gfortran --version
GNU Fortran (GCC) 14.0.0 20230808 (experimental)

$ gfortran -mtune=native -march=native -fcheck=all -std=f2018 -Wall -Werror -Wextra -g -fdump-tree-original -o test.exe test.f90

$ cat test.f90.005t.original

__attribute__((fn spec (". ")))
void test ()
{
  static logical(kind=4) is_recursive.0 = 0;
  character(kind=1) cc[1:32];

  try
    {
      if (is_recursive.0)
        {
          _gfortran_runtime_error_at (&"At line 1 of file test.f90"[1]{lb: 1 sz: 1}, &"Recursive call to nonrecursive procedure \'test\'"[1]{lb: 1 sz: 1});
        }
      is_recursive.0 = 1;
      __builtin_memmove ((void *) &cc, (void *) &"                                "[1]{lb: 1 sz: 1}, 32);
      {
        struct __st_parameter_dt dt_parm.1;

        dt_parm.1.common.filename = &"test.f90"[1]{lb: 1 sz: 1};
        dt_parm.1.common.line = 7;
        dt_parm.1.common.flags = 128;
        dt_parm.1.common.unit = 6;
        _gfortran_st_write (&dt_parm.1);
        {
          character(kind=1) str.2[38];

          _gfortran_concat_string (38, (character(kind=1)[1:] *) &str.2, 6, &" cc : "[1]{lb: 1 sz: 1}, 32, &cc);
          _gfortran_transfer_character_write (&dt_parm.1, (character(kind=1)[1:] *) &str.2, 38);
        }
        _gfortran_st_write_done (&dt_parm.1);
      }
    }
  finally
    {
      is_recursive.0 = 0;
    }
}


__attribute__((externally_visible))
integer(kind=4) main (integer(kind=4) argc, character(kind=1) * * argv)
{
  static integer(kind=4) options.3[7] = {1282, 1947, 0, 1, 1, 1, 31};

  _gfortran_set_args (argc, argv);
  _gfortran_set_options (7, &options.3[0]);
  test ();
  return 0;
}

$ test.exe 

Program received signal SIGILL: Illegal instruction.

Backtrace for this error:
#0  0x14aded839b1f in ???
#1  0x4011c2 in test
        at /home/jdelia/TESTS/test.f90:6
#2  0x4012ae in main
        at /home/jdelia/TESTS/test.f90:8
Illegal instruction (core dumped)


> Regards
> Paul
> 
> On Fri, 11 Aug 2023 at 17:21, Jerry D via Fortran  wrote:
>>
>> 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.  

Ok.

>> 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.

Ok. Thanks.

>> There were some recent patches in this area IIRC.

Ok, although to avoid this problem, we are also using older beta versions.

>> Jerry

Regards,
Jorge.
--