amdclang -fopenmp-version=60: compile does not finish on #pragma omp requires device_safesync

Legality: contested. An independent adjudicating reading finds the result not required: The directive is conforming, but support for a given requirement clause is implementation defined, and an implementation that does not support it must perform compile-time error termination. A compiler may thus refuse the program, so acceptance is not 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	fails another way	fails another way	unknown not run	unknown not run	unknown not run	n/a	n/a
CCE 20.0.2	fails another way	fails another way	unknown not run	unknown not run	unknown not run	n/a	n/a
CCE 21.0.3	fails another way	fails another way	unknown not run	unknown not run	unknown not run	n/a	n/a
CCE 21.0.4	fails another way	fails another way	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	fails another way	fails another way	fails another way	fails another way	fails another way	fails another way	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 AFAR 24.3.0, MI300X AFAR 24.3.0, MI350X	show COMPILE_TIMEOUT
fails another way	CCE 19.0.0, MI300A unified CCE 19.0.0, MI300A copy CCE 20.0.2, MI300A unified CCE 20.0.2, MI300A copy CCE 21.0.3, MI300A unified CCE 21.0.3, MI300A copy CCE 21.0.4, MI300A unified CCE 21.0.4, MI300A copy	show afar-clang-requires-device-safesync-hang.c:1:22: warning: extra tokens at the end of '#pragma omp requires' are ignored [-Wextra-tokens] 1 \| #pragma omp requires device_safesync \| ^ afar-clang-requires-device-safesync-hang.c:1:37: error: expected at least one clause on '#pragma omp requires' directive 1 \| #pragma omp requires device_safesync \| ^ 1 warning and 1 error generated.
fails another way	NVHPC 25.11, A100 separate NVHPC 25.11, A100 managed NVHPC 26.9, A100 separate NVHPC 26.9, A100 managed	show "afar-clang-requires-device-safesync-hang.c", line 1: error: invalid text in pragma #pragma omp requires device_safesync ^ "afar-clang-requires-device-safesync-hang.c", line 1: error: extra text after expected end of preprocessing directive #pragma omp requires device_safesync ^ 2 errors detected in the compilation of "afar-clang-requires-device-safesync-hang.c".
fails another way	GCC 16.2.0, MI300A unified GCC 16.2.0, MI300A copy GCC 16.2.0, MI250X GCC 16.2.0, MI300X GCC 16.2.0, MI350X GCC 16.2.0, A100 separate	show afar-clang-requires-device-safesync-hang.c:1:22: error: expected ‘unified_address’, ‘unified_shared_memory’, ‘self_maps’, ‘dynamic_allocators’, ‘reverse_offload’ or ‘atomic_default_mem_order’ clause 1 \| #pragma omp requires device_safesync \| ^~~~~~~~~~~~~~~

Reproduce

AFAR 24.3.0, MI300A unified

$AFAR/bin/amdclang -fopenmp --offload-arch=gfx942 -fopenmp-version=60 -fopenmp-version=60 -O2 repro.c -o repro
HSA_XNACK=1 OMP_TARGET_OFFLOAD=mandatory ./repro

Program (19 lines)

/* Finding (C): AFAR amdclang hangs on requires device_safesync.

   Legal OpenMP 6.0 C (6.0 §10.5.1.7: device_safesync is a requires
   clause; without an argument it means device_safesync(true)).

   Observed (2026-10-19): amdclang (AFAR 24.0.0git, drop 24.3.0) does not
   finish on this file: killed after 90 s with
   `-fopenmp -fopenmp-version=60 --offload-arch=gfx942 -c`, after 300 s
   with `-fopenmp -fopenmp-version=60 -fsyntax-only`, and after 30 s with
   `-fopenmp-version=52 -fsyntax-only` (where the clause is unknown and
   should be diagnosed). The omp60-c-clause-device_safesync programs time
   out in compilation. CCE craycc 19.0.0, 20.0.2 and 21.0.3 stop at once:
   "warning: extra tokens at the end of '#pragma omp requires' are
   ignored" and "error: expected at least one clause on '#pragma omp
   requires' directive" (the clause is unknown to them). AFAR amdflang
   compiles and runs the Fortran form (`!$omp requires device_safesync`;
   omp60-clause-device_safesync: unobservable). */
#pragma omp requires device_safesync
int main(void) { return 0; }

Source in the repository

Something to add? Dispute its legality · Report it fixed in a newer release · Report a mistake on this page

What the specification requires

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

OpenMP 6.0 §10.5.1.7

Evidence

Same compiler, one change

another requires clause, atomic_default_mem_order(seq_cst): 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
```
#pragma omp requires atomic_default_mem_order(seq_cst)
int main(void) { return 0; }
```