amdflang: an unnamed critical in a target parallel do does not exclude other threads (lost updates)

! # Draft finding: omp52-w-critical on afar
!
! - compiler: afar
! - toolchain: afar; arch: gfx942; machine: tuolumne; memory mode: unified; opt: -O2
! - program: catalog omp52-w-critical (f90, version 52, sha256 7f0f6d194e31f04f)
! - expected: check=pass (trusted; elision + model)
! - actual: wrong_answer check=fail (check_fail: ran_on_host=0 check=fail)
! - oracle audit: run on AFAR, CCE 19, 20, 21 (copy mode) and NVHPC: no toolchain passes the original (CCE ICEs, NVHPC
!   rejects), so the mutant cannot be credited (unaudited, not weak); the C port's identical check is valid (its mutant killed on
!   AFAR), and the mutant fails only by a race (a device effect)
! - verdict: compiler_bug by rule R20-runtime-bug: a legal program fails at run time, deterministically, against an expected value
!   from two or more independent sources with an executed witness, and another toolchain, mode, arch or the elision gives the
!   expected value
! - reason: expected trusted check=pass (elision + model): stored main verdict: elision + model agree; witnesses: afar/gfx942/copy
!   (port:omp52-c-w-critical), afar/gfx942/unified (port:omp52-c-w-critical), cce19/gfx942/copy (port:omp52-c-w-critical), cc ...
! - citations: RUL-DERIVED-NEEDS-EXECUTION (rulings.md); RUL-WITNESS-PER-MODE (rulings.md);
!   RUL-SAME-COMPILER-RUNS (rulings.md); RUL-PRESENCE-WITNESS (rulings.md); RUL-METAMORPHIC-OTHER-FAMILY
!   (rulings.md)
! - legality: legal: offload.engine.rules accepts it (offload.engine.prerun.check, rerun: with the
!   race rule and the restriction checks); NVHPC is no witness: it does not implement a feature the
!   program uses (NVFORTRAN-F-1196-OpenMP - omp critical is not supported in GPU
!   region); the check's other witness, the AFAR flang front end, is the compiler under test and is
!   not counted; no gfortran or gcc is a legality witness
! - witnesses: afar/gfx942/copy (port:omp52-c-w-critical), afar/gfx942/unified (port:omp52-c-w-critical), cce19/gfx942/copy
!   (port:omp52-c-w-critical), cce19/gfx942/unified (port:omp52-c-w-critical), cce20/gfx942/copy (port:omp52-c-w-critical),
!   cce20/gfx94 ...
! - withdrawn: none
!
! Generated by compliance.widen (OpenMP 5.2, free-form Fortran; catalog widening). Do not edit.
! id: omp52-w-critical
! primary atom: omp.directive.critical
! atoms: omp.directive.critical
! legal: yes
! observable: yes
! ran_on_host: inside the target region of interest
! evidence: construct
! needs: none
! std: f2008
! feature: an unnamed critical construct in a target parallel loop
! spec: OpenMP 5.2 §15.2, p.299 (critical construct); its binding thread set is the contention group, so a target parallel region
! (one team) is used
program wide_prog
  use omp_lib, only: omp_is_initial_device
  implicit none
  integer, parameter :: n = 64
  integer :: a(n), b(n), ref(n)
  integer :: s, t
  integer :: i, host_flag
  logical :: ok
  do i = 1, n
    a(i) = i
    b(i) = 0
    ref(i) = 2*i + 1
  end do
  host_flag = 1
  s = 0
  !$omp target parallel do map(to: a) map(tofrom: s, host_flag) private(t)
  do i = 1, n
    !$omp critical
    t = s
    s = t + a(i)
    !$omp end critical
    if (i == 1) host_flag = merge(1, 0, omp_is_initial_device())
  end do
  !$omp end target parallel do
  ok = s == n*(n + 1)/2
  print '(a,i0,a,a)', 'RESULT ran_on_host=', host_flag, ' check=', merge('pass', 'fail', ok)
end program wide_prog