OpenMP: lvalue parsing for map/to/from clauses (C++)

This patch supports "lvalue" parsing (or "locator list item type" parsing)
for several OpenMP clause types for C++, as required for OpenMP 5.0
and above.

This version has been rebased -- some things have changed around
template handling recently, e.g. removal of build_non_dependent_expr and
tsubst_copy.  A new potential corner-case issue has shown up regarding
implicit mapping of references to pointer to pointers -- an interaction
with the post-review fixes/rework for the patch here:

  https://gcc.gnu.org/pipermail/gcc-patches/2023-November/638602.html

Which fixed the (new) tests baseptrs-[6789].C.  I've noted that for now in
the patch, and adjusted the baseptrs-[46].C tests slightly to accommodate.

2024-01-08  Julian Brown  <julian@codesourcery.com>

gcc/c-family/
	* c-common.h (c_omp_address_inspector): Remove static from get_origin
	and maybe_unconvert_ref methods.
	* c-omp.cc (c_omp_split_clauses): Support OMP_ARRAY_SECTION.
	(c_omp_address_inspector::map_supported_p): Handle OMP_ARRAY_SECTION.
	(c_omp_address_inspector::get_origin): Avoid dereferencing possibly
	NULL type when processing template decls.
	(c_omp_address_inspector::maybe_unconvert_ref): Likewise.

gcc/cp/
	* constexpr.cc (potential_consant_expression_1): Handle
	OMP_ARRAY_SECTION.
	* cp-tree.h (grok_omp_array_section, build_omp_array_section): Add
	prototypes.
	* decl2.cc (grok_omp_array_section): New function.
	* error.cc (dump_expr): Handle OMP_ARRAY_SECTION.
	* parser.cc (cp_parser_new): Initialize parser->omp_array_section_p.
	(cp_parser_statement_expr): Disallow array sections.
	(cp_parser_postfix_open_square_expression): Support OMP_ARRAY_SECTION
	parsing.
	(cp_parser_parenthesized_expression_list, cp_parser_lambda_expression,
	cp_parser_braced_list): Disallow array sections.
	(cp_parser_omp_var_list_no_open): Remove ALLOW_DEREF parameter, add
	MAP_LVALUE in its place.  Support generalised lvalue parsing for
	OpenMP map, to and from clauses.  Use OMP_ARRAY_SECTION
	code instead of TREE_LIST to represent OpenMP array sections.
	(cp_parser_omp_var_list): Remove ALLOW_DEREF parameter, add MAP_LVALUE.
	Pass to cp_parser_omp_var_list_no_open.
	(cp_parser_oacc_data_clause): Update call to cp_parser_omp_var_list.
	(cp_parser_omp_clause_map): Add sk_omp scope around
	cp_parser_omp_var_list_no_open call.
	* parser.h (cp_parser): Add omp_array_section_p field.
	* pt.cc (tsubst, tsubst_copy, tsubst_omp_clause_decl,
	tsubst_copy_and_build): Add OMP_ARRAY_SECTION support.
	* semantics.cc (handle_omp_array_sections_1, handle_omp_array_sections,
	cp_oacc_check_attachments, finish_omp_clauses): Use OMP_ARRAY_SECTION
	instead of TREE_LIST where appropriate.  Handle more types of map
	expression.
	* typeck.cc (build_omp_array_section): New function.

gcc/
	* gimplify.cc (gimplify_expr): Ensure OMP_ARRAY_SECTION has been
	processed out before gimplification.
	* tree-pretty-print.cc (dump_generic_node): Support OMP_ARRAY_SECTION.
	* tree.def (OMP_ARRAY_SECTION): New tree code.

gcc/testsuite/
	* c-c++-common/gomp/map-6.c: Update expected output.
	* c-c++-common/gomp/target-enter-data-1.c: Update scan test.
	* g++.dg/gomp/array-section-1.C: New test.
	* g++.dg/gomp/array-section-2.C: New test.
	* g++.dg/gomp/bad-array-section-1.C: New test.
	* g++.dg/gomp/bad-array-section-2.C: New test.
	* g++.dg/gomp/bad-array-section-3.C: New test.
	* g++.dg/gomp/bad-array-section-4.C: New test.
	* g++.dg/gomp/bad-array-section-5.C: New test.
	* g++.dg/gomp/bad-array-section-6.C: New test.
	* g++.dg/gomp/bad-array-section-7.C: New test.
	* g++.dg/gomp/bad-array-section-8.C: New test.
	* g++.dg/gomp/bad-array-section-9.C: New test.
	* g++.dg/gomp/bad-array-section-10.C: New test.
	* g++.dg/gomp/bad-array-section-11.C: New test.
	* g++.dg/gomp/has_device_addr-non-lvalue-1.C: New test.
	* g++.dg/gomp/pr67522.C: Update expected output.
	* g++.dg/gomp/ind-base-3.C: New test.
	* g++.dg/gomp/map-assignment-1.C: New test.
	* g++.dg/gomp/map-inc-1.C: New test.
	* g++.dg/gomp/map-lvalue-ref-1.C: New test.
	* g++.dg/gomp/map-ptrmem-1.C: New test.
	* g++.dg/gomp/map-ptrmem-2.C: New test.
	* g++.dg/gomp/map-static-cast-lvalue-1.C: New test.
	* g++.dg/gomp/map-ternary-1.C: New test.
	* g++.dg/gomp/member-array-2.C: New test.

libgomp/
	* testsuite/libgomp.c++/baseptrs-4.C: Remove commented-out cases that
	now work.
	* testsuite/libgomp.c++/baseptrs-6.C: New test.
	* testsuite/libgomp.c++/ind-base-1.C: New test.
	* testsuite/libgomp.c++/ind-base-2.C: New test.
	* testsuite/libgomp.c++/lvalue-tofrom-1.C: New test.
	* testsuite/libgomp.c++/lvalue-tofrom-2.C: New test.
	* testsuite/libgomp.c++/map-comma-1.C: New test.
	* testsuite/libgomp.c++/map-rvalue-ref-1.C: New test.
	* testsuite/libgomp.c++/struct-ref-1.C: New test.
	* testsuite/libgomp.c-c++-common/array-field-1.c: New test.
	* testsuite/libgomp.c-c++-common/array-of-struct-1.c: New test.
	* testsuite/libgomp.c-c++-common/array-of-struct-2.c: New test.

2 files changed, 23 insertions, 4 deletions

diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 3c2d75a..2d5f539 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1373,8 +1373,8 @@ public:
 
   bool map_supported_p ();
 
-  static tree get_origin (tree);
-  static tree maybe_unconvert_ref (tree);
+  tree get_origin (tree);
+  tree maybe_unconvert_ref (tree);
 
   bool maybe_zero_length_array_section (tree);
 
diff --git a/gcc/c-family/c-omp.cc b/gcc/c-family/c-omp.cc
index 5bceb9c..5117022 100644
--- a/gcc/c-family/c-omp.cc
+++ b/gcc/c-family/c-omp.cc
@@ -2830,6 +2830,9 @@ c_omp_split_clauses (location_t loc, enum tree_code code,
 		    }
 		  else if (TREE_CODE (OMP_CLAUSE_DECL (c)) == TREE_LIST)
 		    {
+		      /* TODO: This can go away once we transition all uses of
+			 TREE_LIST for representing OMP array sections to
+			 OMP_ARRAY_SECTION.  */
 		      tree t;
 		      for (t = OMP_CLAUSE_DECL (c);
 			   TREE_CODE (t) == TREE_LIST; t = TREE_CHAIN (t))
@@ -2838,6 +2841,17 @@ c_omp_split_clauses (location_t loc, enum tree_code code,
 			bitmap_clear_bit (&allocate_head, DECL_UID (t));
 		      break;
 		    }
+		  else if (TREE_CODE (OMP_CLAUSE_DECL (c)) == OMP_ARRAY_SECTION)
+		    {
+		      tree t;
+		      for (t = OMP_CLAUSE_DECL (c);
+			   TREE_CODE (t) == OMP_ARRAY_SECTION;
+			   t = TREE_OPERAND (t, 0))
+			;
+		      if (DECL_P (t))
+			bitmap_clear_bit (&allocate_head, DECL_UID (t));
+		      break;
+		    }
 		  /* FALLTHRU */
 		case OMP_CLAUSE_PRIVATE:
 		case OMP_CLAUSE_FIRSTPRIVATE:
@@ -3379,6 +3393,7 @@ c_omp_address_inspector::map_supported_p ()
 	 || TREE_CODE (t) == SAVE_EXPR
 	 || TREE_CODE (t) == POINTER_PLUS_EXPR
 	 || TREE_CODE (t) == NON_LVALUE_EXPR
+	 || TREE_CODE (t) == OMP_ARRAY_SECTION
 	 || TREE_CODE (t) == NOP_EXPR)
     if (TREE_CODE (t) == COMPOUND_EXPR)
       t = TREE_OPERAND (t, 1);
@@ -3408,7 +3423,8 @@ c_omp_address_inspector::get_origin (tree t)
       else if (TREE_CODE (t) == POINTER_PLUS_EXPR
 	       || TREE_CODE (t) == SAVE_EXPR)
 	t = TREE_OPERAND (t, 0);
-      else if (TREE_CODE (t) == INDIRECT_REF
+      else if (!processing_template_decl_p ()
+	       && TREE_CODE (t) == INDIRECT_REF
 	       && TREE_CODE (TREE_TYPE (TREE_OPERAND (t, 0))) == REFERENCE_TYPE)
 	t = TREE_OPERAND (t, 0);
       else
@@ -3425,7 +3441,10 @@ c_omp_address_inspector::get_origin (tree t)
 tree
 c_omp_address_inspector::maybe_unconvert_ref (tree t)
 {
-  if (TREE_CODE (t) == INDIRECT_REF
+  /* Be careful not to dereference the type if we're processing a
+     template decl, else it might be NULL.  */
+  if (!processing_template_decl_p ()
+      && TREE_CODE (t) == INDIRECT_REF
       && TREE_CODE (TREE_TYPE (TREE_OPERAND (t, 0))) == REFERENCE_TYPE)
     return TREE_OPERAND (t, 0);