[Patch] OpenMP/Fortran: Fix defaultmap(none) issue with dummy procedures [PR114283]

[Tobias Burnus <tburnus@baylibre.com>]

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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.

Comments? Suggestions?

Tobias

PS: Procedure pointers aren't variables either, but they act even more like
variables as they permit changing pointer association such that '(first)private'
vs. 'shared'/'map' can both make sense. — GCC accepts those in (nearly) all clauses,
ifort only in (first)private while flang not at all. The spec is somewhat silent
about it. This is tracked in the same PR (PR114283) and in the specification
issue #3823.

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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