Appears to behave incorrectlyCompiler crash · Fortran · OpenMP · Open

ftn: internal compiler error for lastprivate(conditional:) on a parallel loop in a target region

Legality: not independently confirmed. no independent review yet How this is checked

Same issue as fuzz/1540-afar; this program is another reproducer of it.

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	fails another way	fails another way	unknown not run	fails another way	fails another way	n/a	n/a
CCE 19.0.0	behaves incorrectly	behaves incorrectly	unknown not run	unknown not run	unknown not run	n/a	n/a
CCE 20.0.2	behaves incorrectly	behaves incorrectly	unknown not run	unknown not run	unknown not run	n/a	n/a
CCE 21.0.3	behaves incorrectly	behaves incorrectly	unknown not run	unknown not run	unknown not run	n/a	n/a
CCE 21.0.4	behaves incorrectly	behaves incorrectly	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	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
behaves incorrectly	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.. .true. != 99 Error message :: Mismatched last induction expression for last private operators Error detected :: File '/workspace/crayftn/pdgcs/v_mt_translate.c', line 871 Initiated from :: Line 1849 (v_main.c) Optimizer built :: 2025-02-07 (production) File :: fuzz-958-cce20.f90
behaves incorrectly	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.. .true. != 99 Error message :: Mismatched last induction expression for last private operators Error detected :: File '/workspace/crayftn/pdgcs/v_mt_translate.c', line 901 Initiated from :: Line 1859 (v_main.c) Optimizer built :: 2025-11-17 (production) File :: fuzz-958-cce20.f90
behaves incorrectly	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.. .true. != 99 Error message :: Mismatched last induction expression for last private operators Error detected :: File '/workspace/crayftn/pdgcs/v_mt_translate.c', line 911 Initiated from :: Line 1939 (v_main.c) Optimizer built :: 2026-07-14 (production) File :: fuzz-958-cce20.f90
behaves incorrectly	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.. .true. != 99 Error message :: Mismatched last induction expression for last private operators Error detected :: File '/workspace/crayftn/pdgcs/v_mt_translate.c', line 911 Initiated from :: Line 1939 (v_main.c) Optimizer built :: 2026-09-24 (production) File :: fuzz-958-cce20.f90
fails another way	AFAR 24.3.0, MI300A unified AFAR 24.3.0, MI300A copy AFAR 24.3.0, MI300X AFAR 24.3.0, MI350X	show error: loc("fuzz-958-cce20.f90":7:9): 'omp.target' op SPMD kernel must capture an 'omp.loop_nest' operation error: verification of lowering to FIR failed
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-S-0034-Syntax error at or near : (fuzz-958-cce20.f90: 7) 0 inform, 0 warnings, 1 severes, 0 fatal for fuzz_prog

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

GCC 16.2.0, MI300A unified (runs correctly)

export LD_LIBRARY_PATH=$GCC_16_2/lib64:/opt/rocm-7.2.1/lib
$GCC_16_2/bin/gfortran -fopenmp -foffload=amdgcn-amdhsa -foffload-options=amdgcn-amdhsa=-march=gfx942 -O2 repro.f90 -o repro
HSA_XNACK=1 OMP_TARGET_OFFLOAD=mandatory ./repro

Program (37 lines)

! Minimized by compliance.fuzz_min from fuzz seed 958 (fuzz-1).
! toolchain: cce20 (-O2, HSA_XNACK=1, OMP_TARGET_OFFLOAD=mandatory)
! failure: ice (ice: INTERNAL COMPILER ERROR: "Mismatched last induction expression for last private operators" (v_mt_translate.c,
!   line 901, version <v>))
! expected: compiles
! observed: internal compiler error: ice: INTERNAL COMPILER ERROR:  "Mismatched last induction expression for last private
!   operators" (/workspace/crayftn/pdgcs/v_mt_translate.c, line 901, version 6
! Legal OpenMP 5.2: offload.engine.prerun.check accepts it (rerun: offload.engine.rules with the
!   race rule and the restriction checks, and the AFAR flang front end, not under test here); no
!   compiler under test, gfortran or gcc is a legality witness.
! also fails on: afar, cce19, cce21
module fuzz_mod
  implicit none
contains
  integer function g1(x, y)
    !$omp declare target
    integer, intent(in) :: x, y
    g1 = mod(x, 1009)
  end function g1
end module fuzz_mod
program fuzz_prog
  use fuzz_mod, only: g1
  implicit none
  integer, parameter :: n = 100, m = 8
  integer :: i, j, lp1
  integer(8) :: cs
  lp1 = 0
  ! fuzz: kernels
  !$omp target parallel do lastprivate(conditional: lp1)
  do i = 1, n
    if (mod(i, 3) == 0) lp1 = 0
  end do
  ! fuzz: checksum
  cs = 0
  cs = modulo(cs * 31_8 + int(lp1, 8), 2147483629_8)
  print '(a,i0,a,i0)', 'RESULT checksum=', cs, ' ran_on_host=', 0
end program fuzz_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..
.true. != 99
   Error message      ::  Mismatched last induction expression for last private operators
   Error detected     ::  File '/workspace/crayftn/pdgcs/v_mt_translate.c', line 871
   Initiated from     ::  Line 1849 (v_main.c)
   Optimizer built    ::  2025-02-07 (production)
   File               ::  fuzz-958-cce20.f90

What the specification requires

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

The same requirement as the issue fuzz/1540-afar.

OpenMP 5.2 §5.4.5 p.115 l.16-19

When the conditional modifier appears on the clause or the list item is an iteration variable of one of the associated loops, if sequential execution of the loop nest would assign a value to the list item then the original list item is assigned the value that the list item would have after sequential execution of the loop nest.

OpenMP 5.2 §17.2 p.340 l.27-30

If the target construct is among the constituent constructs and the list item is not the base variable or base pointer of a list item that appears in a map clause, the effect of the lastprivate clause is as if the same list item appears in a map clause with a map-type of tofrom.

Evidence

Same compiler, one change

the same loop on the host (parallel do instead of target parallel do): 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 = 100
  integer :: i, lp1
  integer(8) :: cs
  lp1 = 0
  !$omp parallel do lastprivate(conditional: lp1)
  do i = 1, n
    if (mod(i, 3) == 0) lp1 = 0
  end do
  cs = 0
  cs = modulo(cs * 31_8 + int(lp1, 8), 2147483629_8)
  print '(a,i0)', 'RESULT checksum=', cs
end program fuzz_prog

Other compilers run it correctly

GCC 16.2.0