Observed issues › fuzz/b3-54-afar
amdflang: an empty target nowait with depend(inout:) on a derived-type variable with an allocatable component crashes (SIGSEGV)
Legality: independently confirmed. 2 independent readings find the program legal and the result required. How this is checked
Affected variants
| Compiler | MI300A gfx942 unified memory (XNACK 1) | MI300A gfx942 copy (XNACK 0) | MI250X gfx90a copy (XNACK 0) | MI300X gfx942 copy (XNACK 0) | MI350X gfx950 copy (XNACK 0) | A100 sm_80 separate memory | A100 sm_80 managed memory |
|---|---|---|---|---|---|---|---|
| AFAR 24.3.0 | behaves incorrectly | behaves incorrectly | unknown not run | behaves incorrectly | behaves incorrectly | n/a | n/a |
| CCE 19.0.0 | correct | correct | unknown not run | unknown not run | unknown not run | n/a | n/a |
| CCE 20.0.2 | correct | correct | unknown not run | unknown not run | unknown not run | n/a | n/a |
| CCE 21.0.3 | correct | correct | unknown not run | unknown not run | unknown not run | n/a | n/a |
| CCE 21.0.4 | correct | correct | unknown not run | unknown not run | unknown not run | n/a | n/a |
| NVHPC 25.11 | n/a | n/a | n/a | n/a | n/a | correct | correct |
| NVHPC 26.9 | n/a | n/a | n/a | n/a | n/a | correct | correct |
| GCC 16.2.0 | correct | correct | correct | correct | correct | correct | n/a |
"behaves incorrectly" / "not supported": this issue, confirmed in up to four environments (another build directory, another node, a repeat). "fails another way": a different failure, not counted as this issue. "unknown": not run there, or the runs disagree.
Messages
| Result | Compiler and GPU | Message |
|---|---|---|
| behaves incorrectly | AFAR 24.3.0, MI300A unified AFAR 24.3.0, MI300A copy | showRUN_FAIL |
| behaves incorrectly | AFAR 24.3.0, MI300X AFAR 24.3.0, MI350X | showtimeout: the monitored command dumped core |
Reproduce
AFAR 24.3.0, MI300A unified
$AFAR/bin/amdflang -fopenmp --offload-arch=gfx942 -O2 repro.f90 -o repro HSA_XNACK=1 OMP_TARGET_OFFLOAD=mandatory ./repro
CCE 19.0.0, MI300A unified (runs correctly)
module load cce/19.0.0 craype-accel-amd-gfx942 rocm/6.4.3 module unload cray-mpich ftn -fopenmp -O2 repro.f90 -o repro HSA_XNACK=1 OMP_TARGET_OFFLOAD=mandatory ./repro
Program (62 lines)
! Minimized by compliance.fuzz_min from fuzz seed 54 (fuzz-3).
! toolchain: afar (-O2, HSA_XNACK=1, OMP_TARGET_OFFLOAD=mandatory)
! failure: run_error (crash: SIGSEGV)
! expected: runs to completion (the host run does)
! observed: device: fail crash: SIGSEGV; host reference (elision) checksum=0
! Legal OpenMP 5.2: offload.engine.rules accepts it (offload.engine.prerun.check, rerun: with the
! race rule and the restriction checks); nvfortran/nvc 26.9 and 25.11 (NVHPC, not under test
! here) compile it; the check's other witness, the AFAR flang front end, is the compiler under
! test and is not counted; no gfortran or gcc is a legality witness.
module fuzz_mod
implicit none
contains
end module fuzz_mod
program fuzz_prog
use omp_lib, only: omp_get_thread_num, omp_is_initial_device
implicit none
integer, parameter :: n = 32, m = 5
type :: rec_t
integer, allocatable :: q(:)
end type rec_t
type(rec_t) :: dr
integer, allocatable, target :: ic(:, :)
integer, pointer :: o1(:)
integer :: i, j, p1, hf1
integer(8) :: cs
allocate(ic(n, m))
allocate(dr%q(n))
allocate(o1(n))
do j = 1, m
do i = 1, n
ic(i, j) = mod((i + 8 * j) * 26 + 35, 97) - 30
end do
end do
do i = 1, n
dr%q(i) = mod(i * 6 + 6, 1009) - 171
end do
o1 = 0
p1 = -3
hf1 = 0
! fuzz: kernels
!$omp target nowait depend(in: p1) depend(inout: dr, hf1, ic, o1)
!$omp end target
!$omp taskwait
! fuzz: checksum
cs = 0
do i = 1, n
cs = modulo(cs * 31_8 + int(o1(i), 8), 2147483629_8)
end do
print '(a,i0,a,i0)', 'RESULT checksum=', cs, ' ran_on_host=', max(hf1, 0)
end program fuzz_prog
! spec (requirement): a depend clause on a target construct is associated with the target task and derives its dependences from
! the storage locations of its list items; a variable of derived type with an allocated allocatable component is a legal list
! item.
! "The target construct generates a target task. The generated task region encloses the target region. If a depend clause is
! present, it is associated with the target task. The device clause determines the device on which the target region executes.
! If the nowait clause is present," (5.2 §13.8 p.284 l.14-16)
! "The depend clause enforces additional constraints on the scheduling of tasks. These constraints establish dependences only
! between sibling tasks. Task dependences are derived from the task-dependence-type and the list items." (5.2 §15.9.5 p.323
! l.16-18)
! spec (this program): target nowait depend(inout: dr, hf1, ic, o1) with an empty body followed by taskwait is legal, dr being a
! derived-type variable with an allocated allocatable component; AFAR crashes (SIGSEGV), and the program is correct when dr is
! removed from the depend clause.
Something to add? Dispute its legality · Report it fixed in a newer release · Report a mistake on this page
Expected and observed
Observed where it behaves incorrectly
timeout: the monitored command dumped core
What the specification requires
The specification text this program relies on and the compiler is expected to support.
OpenMP 5.2 §13.8 p.284 l.14-16
The target construct generates a target task. The generated task region encloses the target region. If a depend clause is present, it is associated with the target task. The device clause determines the device on which the target region executes. If the nowait clause is present,
OpenMP 5.2 §15.9.5 p.323 l.16-18
The depend clause enforces additional constraints on the scheduling of tasks. These constraints establish dependences only between sibling tasks. Task dependences are derived from the task-dependence-type and the list items.
Evidence
Same compiler, one change
- dr removed from the depend clause: AFAR 24.3.0: correct; CCE 19.0.0: correct; CCE 20.0.2: correct; CCE 21.0.3: correct; CCE 21.0.4: correct
Control program
program fuzz_prog implicit none integer, parameter :: n = 32, m = 5 type :: rec_t integer, allocatable :: q(:) end type rec_t type(rec_t) :: dr integer, allocatable, target :: ic(:, :) integer, pointer :: o1(:) integer :: i, j, p1, hf1 integer(8) :: cs allocate(ic(n, m)) allocate(dr%q(n)) allocate(o1(n)) do j = 1, m do i = 1, n ic(i, j) = mod((i + 8 * j) * 26 + 35, 97) - 30 end do end do do i = 1, n dr%q(i) = mod(i * 6 + 6, 1009) - 171 end do o1 = 0 p1 = -3 hf1 = 0 !$omp target nowait depend(in: p1) depend(inout: hf1, ic, o1) !$omp end target !$omp taskwait cs = 0 do i = 1, n cs = modulo(cs * 31_8 + int(o1(i), 8), 2147483629_8) end do print '(a,i0)', 'RESULT checksum=', cs end program fuzz_prog
Other compilers run it correctly
CCE 19.0.0, CCE 20.0.2, CCE 21.0.3, CCE 21.0.4, NVHPC 25.11, NVHPC 26.9, GCC 16.2.0