https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108749
Bug ID: 108749
Summary: [OpenMP][C/C++/Fortran] inscan reduction modifier
rejected for combined/composite constructs of
simd/for/do
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Keywords: openmp, rejects-valid
Severity: normal
Priority: P3
Component: other
Assignee: unassigned at gcc dot gnu.org
Reporter: burnus at gcc dot gnu.org
CC: jakub at gcc dot gnu.org
Target Milestone: ---
This applies to C, C++ and Fortran likewise.
test.c:6:37: error: ‘inscan’ ‘reduction’ clause on construct other than ‘for’,
‘simd’, ‘for simd’, ‘parallel for’, ‘parallel for simd’
6 | #pragma omp target simd reduction (inscan, *:r)
| ^
OpenMP 5.0 had the following:
"A reduction clause with the *inscan* reduction-modifier may only appear on a
worksharing-loop construct, a worksharing-loop SIMD construct, a simd
construct, a parallel worksharing-loop construct or a parallel worksharing-loop
SIMD construct."
But, a bit confusingly, it also had:
"If a construct to which the *inscan* reduction-modifier is
applied is combined with the *target* construct, the effect is as if the same
list item also appears in a map clause with a map-type of tofrom."
The latter implying that a combined construct is also permitted - while the
former rules it out.
* * *
OpenMP 5.1 seemingly fixed this while 5.2 removed constructs with 'distribute'.
In any case, OpenMP 5.2 reads as follows:
"A reduction clause with the *inscan* reduction-modifier may only appear on a
worksharing-loop construct, a simd construct or a combined or composite
construct for which any of the aforementioned constructs is a constituent
construct and distribute is not a constituent construct." — ["5.5.8 reduction
Clause" under "Restrictions to the reduction clause are as follows:" (7th
bullet), [136:1-4]]
* * *
I think this currently implies that the following ones should be supported
besides the exsisting '(parallel) {do|for} (simd)' and 'simd'.
OMP_MASKED_TASKLOOP_SIMD
OMP_MASTER_TASKLOOP_SIMD
OMP_PARALLEL_MASKED_TASKLOOP_SIMD
OMP_PARALLEL_MASTER_TASKLOOP_SIMD
OMP_TARGET_PARALLEL_DO
OMP_TARGET_PARALLEL_DO_SIMD
OMP_TARGET_SIMD
OMP_TASKLOOP_SIMD
