openmp: Introduce gimple_omp_ordered_standalone_p

On Sat, Sep 03, 2022 at 10:07:27AM +0200, Jakub Jelinek via Gcc-patches wrote:
> Incrementally, I'd like to change the way we differentiate between
> stand-alone and block-associated ordered constructs, because the current
> way of looking for presence of doacross clause doesn't work well if those
> clauses are removed because they had been invalid (wrong syntax or
> unknown variables in it etc.)

The following, so far only lightly tested, patch implements that.

2022-09-06  Jakub Jelinek  <jakub@redhat.com>

gcc/
	* gimple.h (enum gf_mask): Add GF_OMP_ORDERED_STANDALONE enumerator.
	(gimple_omp_subcode):  Use GIMPLE_OMP_ORDERED instead of
	GIMPLE_OMP_TEAMS as upper bound.
	(gimple_omp_ordered_standalone_p, gimple_omp_ordered_standalone): New
	inline functions.
	* gimplify.cc (find_standalone_omp_ordered): Look for OMP_ORDERED with
	NULL OMP_ORDERED_BODY rather than with OMP_DOACROSS clause.
	(gimplify_expr): Call gimple_omp_ordered_standalone for OMP_ORDERED
	with NULL OMP_ORDERED_BODY.
	* omp-low.cc (check_omp_nesting_restrictions): Use
	gimple_omp_ordered_standalone_p test instead of
	omp_find_clause (..., OMP_CLAUSE_DOACROSS).
	(lower_omp_ordered): Likewise.
	* omp-expand.cc (expand_omp, build_omp_regions_1,
	omp_make_gimple_edges): Likewise.
gcc/cp/
	* pt.cc (tsubst_expr) <case OMP_ORDERED>: If OMP_BODY was NULL, keep
	it NULL after instantiation too.
gcc/testsuite/
	* c-c++-common/gomp/sink-3.c: Don't expect a superfluous error during
	error recovery.
	* c-c++-common/gomp/doacross-6.c (foo): Add further tests.

1 files changed, 8 insertions, 3 deletions

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index cd0d892..c5fc0f1 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -19526,9 +19526,14 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl,
     case OMP_ORDERED:
       tmp = tsubst_omp_clauses (OMP_ORDERED_CLAUSES (t), C_ORT_OMP, args,
 				complain, in_decl);
-      stmt = push_stmt_list ();
-      RECUR (OMP_BODY (t));
-      stmt = pop_stmt_list (stmt);
+      if (OMP_BODY (t))
+	{
+	  stmt = push_stmt_list ();
+	  RECUR (OMP_BODY (t));
+	  stmt = pop_stmt_list (stmt);
+	}
+      else
+	stmt = NULL_TREE;
 
       t = copy_node (t);
       OMP_BODY (t) = stmt;