| Message ID | fbc758b6-77fc-4cbd-81bc-ab7137061e5c@baylibre.com |
|---|---|
| State | New |
| Headers | show |
| Series | OpenMP/Fortran: Fix defaultmap(none) issue with dummy procedures [PR114283] | expand |
On Mon, Mar 11, 2024 at 11:07:46AM +0100, Tobias Burnus wrote: > Using dummy procedures in a target region with 'defaultmap(none)' leads to: > > Error: 'g' not specified in enclosing 'target' > > and this cannot be fixed by using 'firstprivate' as non-pointer dummy routines > are rejected as "Error: Object 'g' is not a variable". > > Fixed by doing the same for mapping as for data sharing: using predetermined > firstprivate. > > BTW: Only since GCC 14, 'declare target indirect' makes it possible to > simply use dummy procedures and procedures pointers in a target region. So firstprivate clause handling remaps them then if declare target indirect is used? If so, the patch looks reasonable to me. Jakub
Jakub Jelinek wrote: > So firstprivate clause handling remaps them then if declare target indirect > is used? If so, the patch looks reasonable to me. [I have now updated the patch to turn the testcase to ensure that is also keeps works at runtime.] OpenMP leaves it a bit open when the remapping has to happen, but one can construct cases – in particular with unified-shared memory – where it is not possible to do this upon entry to a target region. Thus, it has to be done when the function is invoked, e.g. i = (*g) (); is turned (in the target region but only on the device side) into i = (*GOMP_target_map_indirect_ptr (g)) (); Thus, as long as the host pointer value is transferred to the device, it works – as the lookup is done on the device side. Directly using a device address (remap when mapping to the target) will also not shorten the lookup, i.e. there is no need for it. Does it still look reasonable to you? Tobias PS: The current OpenMP specification, it is listed mainly described via the glossary (newest change is the addition of dummy procedure): "indirect device invocation – An indirect call to the _device_ version of a _procedure_ on a _device_ other than the _host-device_, through a function pointer (C/C++), a pointer to a member function (C++), a dummy procedure (Fortran), or a procedure pointer (Fortran) that refers to the host version of the _procedure_."
OpenMP/Fortran: Fix defaultmap(none) issue with dummy procedures [PR114283] Dummy procedures look similar to variables but aren't - neither in Fortran nor in OpenMP. As the middle end sees PARM_DECLs, mark them as predetermined firstprivate for mapping (as already done in gfc_omp_predetermined_sharing). This does not address the isses related to procedure pointers, which are still discussed on spec level [see PR]. PR fortran/114283 gcc/fortran/ChangeLog: * trans-openmp.cc (gfc_omp_predetermined_mapping): Map dummy procedures as firstprivate. gcc/testsuite/ChangeLog: * gfortran.dg/gomp/target4.f90: New test. gcc/fortran/trans-openmp.cc | 9 +++++++++ gcc/testsuite/gfortran.dg/gomp/target4.f90 | 18 ++++++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/gcc/fortran/trans-openmp.cc b/gcc/fortran/trans-openmp.cc index a2bf15665b3..1dba47126ed 100644 --- a/gcc/fortran/trans-openmp.cc +++ b/gcc/fortran/trans-openmp.cc @@ -343,6 +343,15 @@ gfc_omp_predetermined_mapping (tree decl) && GFC_DECL_SAVED_DESCRIPTOR (decl))) return OMP_CLAUSE_DEFAULTMAP_TO; + /* Dummy procedures aren't considered variables by OpenMP, thus are + disallowed in OpenMP clauses. They are represented as PARM_DECLs + in the middle-end, so return OMP_CLAUSE_DEFAULTMAP_FIRSTPRIVATE here + to avoid complaining about their uses with defaultmap(none). */ + if (TREE_CODE (decl) == PARM_DECL + && TREE_CODE (TREE_TYPE (decl)) == POINTER_TYPE + && TREE_CODE (TREE_TYPE (TREE_TYPE (decl))) == FUNCTION_TYPE) + return OMP_CLAUSE_DEFAULTMAP_FIRSTPRIVATE; + /* These are either array or derived parameters, or vtables. */ if (VAR_P (decl) && TREE_READONLY (decl) && (TREE_STATIC (decl) || DECL_EXTERNAL (decl))) diff --git a/gcc/testsuite/gfortran.dg/gomp/target4.f90 b/gcc/testsuite/gfortran.dg/gomp/target4.f90 new file mode 100644 index 00000000000..09364e707f1 --- /dev/null +++ b/gcc/testsuite/gfortran.dg/gomp/target4.f90 @@ -0,0 +1,18 @@ +! { dg-additional-options "-fdump-tree-gimple" } + +! PR fortran/114283 + +! { dg-final { scan-tree-dump "#pragma omp parallel default\\(none\\) firstprivate\\(g\\)" "gimple" } } +! { dg-final { scan-tree-dump "#pragma omp target num_teams\\(-2\\) thread_limit\\(0\\) defaultmap\\(none\\) firstprivate\\(g\\)" "gimple" } } + +subroutine f(g) +procedure() :: g + +!$omp parallel default(none) + call g +!$omp end parallel + +!$omp target defaultmap(none) + call g +!$omp end target +end