ftn: C_F_POINTER called in a target region fails at the device link (_C_F_POINTER undefined)

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	correct	correct	correct	correct	correct	n/a	n/a
CCE 19.0.0	not supported	not supported	not supported	unknown not run	unknown not run	n/a	n/a
CCE 20.0.2	not supported	not supported	not supported	unknown not run	unknown not run	n/a	n/a
CCE 21.0.3	not supported	not supported	not supported	unknown not run	unknown not run	n/a	n/a
CCE 21.0.4	not supported	not supported	not supported	unknown not run	unknown not run	n/a	n/a
NVHPC 25.11	n/a	n/a	n/a	n/a	n/a	fails another way	fails another way
NVHPC 26.9	n/a	n/a	n/a	n/a	n/a	fails another way	fails another way
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
not supported	CCE 19.0.0, MI300A unified CCE 19.0.0, MI300A copy	show Warning: Headers and libraries from cray-libsci/25.03.0 will be ignored because depends on PE_MPICH which is unavailable.. lld: error: undefined symbol: _C_F_POINTER >>> referenced by <dir>/cooltmpdir-5HO6vp/repro-cce-openmp__llc.amdgpu:(gen_prog_$ck_L22_1) >>> referenced by <dir>/cooltmpdir-5HO6vp/repro-cce-openmp__llc.amdgpu:(gen_prog_$ck_L22_1)
not supported	CCE 19.0.0, MI250X	show Warning: Headers and libraries from cray-libsci/25.03.0 will be ignored because depends on PE_MPICH which is unavailable.. lld: error: undefined symbol: _C_F_POINTER >>> referenced by <dir>/cooltmpdir-5C8SRY/repro-cce-openmp__llc.amdgpu:(gen_prog_$ck_L22_1) >>> referenced by <dir>/cooltmpdir-5C8SRY/repro-cce-openmp__llc.amdgpu:(gen_prog_$ck_L22_1)
not supported	CCE 20.0.2, MI300A unified CCE 20.0.2, MI300A copy	show Warning: Headers and libraries from cray-libsci/25.09.0 will be ignored because depends on PE_MPICH which is unavailable.. lld: error: undefined symbol: _C_F_POINTER >>> referenced by <dir>/cooltmpdir-6lfXrk/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1) >>> referenced by <dir>/cooltmpdir-6lfXrk/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1)
not supported	CCE 20.0.2, MI250X	show Warning: Headers and libraries from cray-libsci/25.09.0 will be ignored because depends on PE_MPICH which is unavailable.. lld: error: undefined symbol: _C_F_POINTER >>> referenced by <dir>/cooltmpdir-Xe9w0T/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1) >>> referenced by <dir>/cooltmpdir-Xe9w0T/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1)
not supported	CCE 21.0.3, MI300A unified CCE 21.0.3, MI300A copy	show Warning: Headers and libraries from cray-libsci/26.03.0 will be ignored because depends on PE_MPICH which is unavailable.. lld: error: undefined symbol: _C_F_POINTER >>> referenced by <dir>/pe_2677814//cooltmpdir-tqPBJ2/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1) >>> referenced by <dir>/pe_2677814//cooltmpdir-tqPBJ2/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1)
not supported	CCE 21.0.3, MI250X	show Warning: Headers and libraries from cray-libsci/26.03.0 will be ignored because depends on PE_MPICH which is unavailable.. lld: error: undefined symbol: _C_F_POINTER >>> referenced by <dir>/pe_3597796//cooltmpdir-ehcLJG/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1) >>> referenced by <dir>/pe_3597796//cooltmpdir-ehcLJG/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1)
not supported	CCE 21.0.4, MI300A unified CCE 21.0.4, MI300A copy	show Warning: Headers and libraries from cray-libsci/26.03.0 will be ignored because depends on PE_MPICH which is unavailable.. lld: error: undefined symbol: _C_F_POINTER >>> referenced by <dir>/pe_3400038//cooltmpdir-XpJt4J/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1) >>> referenced by <dir>/pe_3400038//cooltmpdir-XpJt4J/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1)
not supported	CCE 21.0.4, MI250X	show Warning: Headers and libraries from cray-libsci/26.03.0 will be ignored because depends on PE_MPICH which is unavailable.. lld: error: undefined symbol: _C_F_POINTER >>> referenced by <dir>/pe_3556018//cooltmpdir-G40wCC/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1) >>> referenced by <dir>/pe_3556018//cooltmpdir-G40wCC/repro-cce-openmppost_lld.amdgpu.lto.o:(gen_prog_$ck_L22_1)
fails another way	NVHPC 25.11, A100 separate NVHPC 25.11, A100 managed NVHPC 26.9, A100 separate NVHPC 26.9, A100 managed	show NVFORTRAN-W-1288-Use of the USE_DEVICE_PTR clause is deprecated, use USE_DEVICE_ADDR clause instead (cce-c-f-pointer-device-link.f90: 21) 0 inform, 1 warnings, 0 severes, 0 fatal for gen_prog NVFORTRAN-S-1058-Call to NVHPC runtime function not supported - pgf90_c_f_ptr_i8 (cce-c-f-pointer-device-link.f90: 24)

Reproduce

CCE 19.0.0, MI300A unified

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

CCE 20.0.2, MI300A unified

module load cce/20.0.2 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

CCE 21.0.3, MI300A unified

module load cce/21.0.3 craype-accel-amd-gfx942 rocm/7.2.0
module unload cray-mpich
ftn -fopenmp -O2 repro.f90 -o repro
HSA_XNACK=1 OMP_TARGET_OFFLOAD=mandatory ./repro

CCE 21.0.4, MI300A unified

module load cce/21.0.4 craype-accel-amd-gfx942 rocm/7.2.0
module unload cray-mpich
ftn -fopenmp -O2 repro.f90 -o repro
HSA_XNACK=1 OMP_TARGET_OFFLOAD=mandatory ./repro

AFAR 24.3.0, MI300A unified (runs correctly)

$AFAR/bin/amdflang -fopenmp --offload-arch=gfx942 -O2 repro.f90 -o repro
HSA_XNACK=1 OMP_TARGET_OFFLOAD=mandatory ./repro

Program (64 lines)

! # Draft finding: omp52-clause-is_device_ptr on cce19
!
! - compiler: cce19
! - toolchain: cce19; arch: gfx942; machine: tuolumne; memory mode: unified; opt: -O2
! - program: catalog omp52-clause-is_device_ptr (f90, version 52, sha256 234487aa9ebe80a4)
! - expected: None (None; )
! - actual: rejected  (link_undefined_symbol: lld: error: undefined symbol: _C_F_POINTER)
! - verdict: compiler_bug by rule R10b-own-link-or-hang: a link failure on symbols the compiler's own generated code needs, or a
!   compile that does not finish, on a legal program: the compiler's defect (never a rejection)
! - reason: 
! - citations: RUL-COMPILE-TIME (rulings.md)
! - legality: legal (legal by construction: offload.engine.gen / c_gen / acc_gen check every program against the catalog rules
!   and the
!   offload scope as it is built (no compiler))
! - witnesses: none
! - withdrawn: none
!
! Generated by compliance.gen (OpenMP 5.2, free-form Fortran). Do not edit.
! id: omp52-clause-is_device_ptr
! primary atom: omp.clause.is_device_ptr
! legal: yes
! observable: yes
! ran_on_host: inside the target region of interest
! evidence: copy_mode_only
! needs: device_c_f_pointer
! std: f2008
! derivation (check=pass): target data maps a (to) and b (from); use_device_ptr(pa, pb) makes pa and pb the device addresses of a
! derivation: and b (5.2 §5.4.8 p.121); the nested target has is_device_ptr(pa, pb), so they are used as device pointers there (5.2
! derivation: §5.4.7 p.120) and qq(i) = 2*pp(i) + 1 writes the device's b; the end of target data copies b back: b = ref; the check
! derivation: accepts
program gen_prog
  use omp_lib, only: omp_is_initial_device
  use, intrinsic :: iso_c_binding, only: c_ptr, c_loc, c_f_pointer
  implicit none
  integer, parameter :: n = 64
  integer, allocatable, target :: a(:), b(:)
  integer :: ref(n)
  integer :: i, host_flag
  logical :: ok
  type(c_ptr) :: pa, pb
  integer, pointer :: pp(:), qq(:)
  allocate(a(n), b(n))
  do i = 1, n
    a(i) = i
    b(i) = 0
    ref(i) = 2*i + 1
  end do
  host_flag = 1
  pa = c_loc(a)
  pb = c_loc(b)
  !$omp target data map(to: a) map(from: b) use_device_ptr(pa, pb)
    !$omp target is_device_ptr(pa, pb) private(pp, qq) map(tofrom: host_flag)
      host_flag = merge(1, 0, omp_is_initial_device())
      call c_f_pointer(pa, pp, [n])
      call c_f_pointer(pb, qq, [n])
      do i = 1, n
        qq(i) = 2*pp(i) + 1
      end do
    !$omp end target
  !$omp end target data
  ok = all(b == ref)
  print '(a,i0,a,a)', 'RESULT ran_on_host=', host_flag, ' check=', merge('pass', 'fail', ok)
  deallocate(a, b)
end program gen_prog

Source in the repository

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

Warning:
 Headers and libraries from cray-libsci/25.03.0 will be ignored because depends on PE_MPICH which is unavailable..
lld: error: undefined symbol: _C_F_POINTER
>>> referenced by <dir>/cooltmpdir-5HO6vp/repro-cce-openmp__llc.amdgpu:(gen_prog_$ck_L22_1)
>>> referenced by <dir>/cooltmpdir-5HO6vp/repro-cce-openmp__llc.amdgpu:(gen_prog_$ck_L22_1)

What the specification requires

The specification text this program relies on and the compiler is expected to support.

OpenMP 5.2 §5.4.8 p.121

OpenMP 5.2 §5.4.7 p.120

Evidence

Same compiler, one change

the device loop reads a and writes b directly instead of through c_f_pointer: 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 gen_prog
  use omp_lib, only: omp_is_initial_device
  use, intrinsic :: iso_c_binding, only: c_ptr, c_loc, c_f_pointer
  implicit none
  integer, parameter :: n = 64
  integer, allocatable, target :: a(:), b(:)
  integer :: ref(n)
  integer :: i, host_flag
  logical :: ok
  type(c_ptr) :: pa, pb
  integer, pointer :: pp(:), qq(:)
  allocate(a(n), b(n))
  do i = 1, n
    a(i) = i
    b(i) = 0
    ref(i) = 2*i + 1
  end do
  host_flag = 1
  pa = c_loc(a)
  pb = c_loc(b)
  !$omp target data map(to: a) map(from: b) use_device_ptr(pa, pb)
    !$omp target is_device_ptr(pa, pb) private(pp, qq) map(tofrom: host_flag)
      host_flag = merge(1, 0, omp_is_initial_device())
      do i = 1, n
        b(i) = 2*a(i) + 1
      end do
    !$omp end target
  !$omp end target data
  ok = all(b == ref)
  print '(a,i0,a,a)', 'RESULT ran_on_host=', host_flag, ' check=', merge('pass', 'fail', ok)
  deallocate(a, b)
end program gen_prog

Other compilers run it correctly

AFAR 24.3.0, GCC 16.2.0