OpenMP/Fortran: Combined directives with map/firstprivate of same symbol

This patch fixes a case where a combined directive (e.g. "!$omp target
parallel ...") contains both a map and a firstprivate clause for the
same variable.  When the combined directive is split into two nested
directives, the outer "target" gets the "map" clause, and the inner
"parallel" gets the "firstprivate" clause, like so:

  !$omp target parallel map(x) firstprivate(x)

  -->

  !$omp target map(x)
    !$omp parallel firstprivate(x)
      ...

When there is no map of the same variable, the firstprivate is distributed
to both directives, e.g. for 'y' in:

  !$omp target parallel map(x) firstprivate(y)

  -->

  !$omp target map(x) firstprivate(y)
    !$omp parallel firstprivate(y)
      ...

This is not a recent regression, but appear to fix a long-standing ICE.
(The included testcase is based on one by Tobias.)

2022-12-06  Julian Brown  <julian@codesourcery.com>

gcc/fortran/
	* trans-openmp.cc (gfc_add_firstprivate_if_unmapped): New function.
	(gfc_split_omp_clauses): Call above.

libgomp/
	* testsuite/libgomp.fortran/combined-directive-splitting-1.f90: New
	test.

1 files changed, 35 insertions, 2 deletions

diff --git a/gcc/fortran/trans-openmp.cc b/gcc/fortran/trans-openmp.cc
index 7a4a339..395bcc9 100644
--- a/gcc/fortran/trans-openmp.cc
+++ b/gcc/fortran/trans-openmp.cc
@@ -5968,6 +5968,39 @@ gfc_add_clause_implicitly (gfc_omp_clauses *clauses_out,
     }
 }
 
+/* Kind of opposite to above, add firstprivate to CLAUSES_OUT if it is mapped
+   in CLAUSES_IN's FIRSTPRIVATE list but not its MAP list.  */
+
+static void
+gfc_add_firstprivate_if_unmapped (gfc_omp_clauses *clauses_out,
+				  gfc_omp_clauses *clauses_in)
+{
+  gfc_omp_namelist *n = clauses_in->lists[OMP_LIST_FIRSTPRIVATE];
+  gfc_omp_namelist **tail = NULL;
+
+  for (; n != NULL; n = n->next)
+    {
+      gfc_omp_namelist *n2 = clauses_out->lists[OMP_LIST_MAP];
+      for (; n2 != NULL; n2 = n2->next)
+	if (n->sym == n2->sym)
+	  break;
+      if (n2 == NULL)
+	{
+	  gfc_omp_namelist *dup = gfc_get_omp_namelist ();
+	  *dup = *n;
+	  dup->next = NULL;
+	  if (!tail)
+	    {
+	      tail = &clauses_out->lists[OMP_LIST_FIRSTPRIVATE];
+	      while (*tail && (*tail)->next)
+		tail = &(*tail)->next;
+	    }
+	  *tail = dup;
+	  tail = &(*tail)->next;
+	}
+    }
+}
+
 static void
 gfc_free_split_omp_clauses (gfc_code *code, gfc_omp_clauses *clausesa)
 {
@@ -6351,8 +6384,8 @@ gfc_split_omp_clauses (gfc_code *code,
 	 simd and masked/master.  Put it on the outermost of those and duplicate
 	 on parallel and teams.  */
       if (mask & GFC_OMP_MASK_TARGET)
-	clausesa[GFC_OMP_SPLIT_TARGET].lists[OMP_LIST_FIRSTPRIVATE]
-	  = code->ext.omp_clauses->lists[OMP_LIST_FIRSTPRIVATE];
+	gfc_add_firstprivate_if_unmapped (&clausesa[GFC_OMP_SPLIT_TARGET],
+					  code->ext.omp_clauses);
       if (mask & GFC_OMP_MASK_TEAMS)
 	clausesa[GFC_OMP_SPLIT_TEAMS].lists[OMP_LIST_FIRSTPRIVATE]
 	  = code->ext.omp_clauses->lists[OMP_LIST_FIRSTPRIVATE];