https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90573
Bug ID: 90573
Summary: Avoid unnecessary data transfer into OMP construct
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Keywords: openacc, openmp
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: tschwinge at gcc dot gnu.org
CC: jakub at gcc dot gnu.org
Target Milestone: ---
As mentioned in PR90067: "it might generally be beneficial to have a pass
promoting 'firstprivate(x)' with a dominating write operation on 'x' to
'private(x)'". This will avoid unnecessary data transfer for (all too common!)
code like:
int i;
#pragma acc parallel loop // implicit 'firstprivate(i)'
for (i = 0; i < N; ++i)
[...]
Similarly, there are cases where 'copy(x)' can be optimized to 'copyout(x)', or
'copyin(x)' to 'create(x)'.
This need not apply to implicit clauses only, but also to explicit ones, when
the user can't observe any difference.
The same applies to certain OpenMP clauses too, I suppose.
