[Flang] Execution does not terminate when an array name enclosed in square brackets is used in where construct

[ohno-fj]

Version of flang : 21.0.0(9fe6f6a0d430b872750354c20f3e4a651bd1f135)/AArch64

When array-constructor (an array name enclosed in square brackets) is used in where construct, execution does not terminate after more than 20 minutes.
Gfortran and ifx execute in less than a second.
The above program is sngtar12_2.f90

According to the Fortran standard 2023: 7.8 Construction of array values, it seems correct to use array names enclosed in square brackets.

Execution terminates in the following cases:

• Do not use where construct
  The above program is sngtar12_21.f90
• Do not use square brackets
  The above program is sngtar12_23.f90

The following are the test program, Flang, Gfortran and ifx compilation/execution result.

sngtar12_2.f90:

program main
  integer a(6000*400), b(6000*400)
  a=1
  where(a>0)
     b=[a]
     b=[a**1]
  end where
  if(b(6000*400)/=1) print *,'err1'
  print *,'pass'
end program

$ flang sngtar12_2.f90; time ./a.out -> Killed because execution does not terminate after more than 20 minutes
  C-c C-c
real    24m34.953s
user    24m9.212s
sys     0m25.710s

$

$ gfortran sngtar12_2.f90; time ./a.out
 pass

real    0m0.056s
user    0m0.033s
sys     0m0.023s
$

$ ifx sngtar12_2.f90; time ./a.out
 pass

real    0m0.255s
user    0m0.002s
sys     0m0.005s
$

sngtar12_21.f90:

program main
  integer a(6000*400), b(6000*400)
  a=1
!  where(a>0)
     b=[a]
     b=[a**1]
!  end where
  if(b(6000*400)/=1) print *,'err1'
  print *,'pass'
end program

$ flang sngtar12_21.f90; time ./a.out
 pass

real    0m0.146s
user    0m0.128s
sys     0m0.011s
$

sngtar12_23.f90:

program main
  integer a(6000*400), b(6000*400)
  a=1
  where(a>0)
     b=a
     b=a**1
  end where
  if(b(6000*400)/=1) print *,'err1'
  print *,'pass'
end program

$ flang sngtar12_23.f90; time ./a.out
 pass

real    0m0.240s
user    0m0.185s
sys     0m0.001s
$

[eugeneepshteyn]

To clarify, compilation is fine:

$ time flang sngtar12_2.f90 

real	0m0.335s
user	0m0.324s
sys	0m0.050s

It's the execution that runs for a long time.

[ceseo]

This seems to be working now:

$ cat sandbox/test.f90
program main
  integer a(6000*400), b(6000*400)
  a=1
  where(a>0)
     b=[a]
     b=[a**1]
  end where
  if(b(6000*400)/=1) print *,'err1'
  print *,'pass'
end program

$ ./build/bin/flang sandbox/test.f90 -o sandbox/test
$ time ./sandbox/test
 pass

real    0m0.243s
user    0m0.044s
sys     0m0.007s

@ohno-fj could you please check with the latest Flang and close it that's the case?

[ohno-fj]

@ceseo thank you for your comment.
I have confirmed that the program terminates normally with the latest Flang.
I close this issue.

The following is the confirmation log.

$ flang sngtar12_2.f90; time ./a.out
 pass

real    0m0.352s
user    0m0.321s
sys     0m0.030s
$