Change C front end to emit structured loop and switch tree nodes.

2020-08-12  Sandra Loosemore  <[email protected]>

	gcc/c
	* c-decl.c (c_break_label, c_cont_label): Delete, and replace
	with...
	(in_statement): New.
	(start_function): Adjust for above change.
	(c_push_function_context, c_pop_function_context): Likewise.
	* c-lang.h (struct language_function): Likewise.
	* c-objc-common.h (LANG_HOOKS_BLOCK_MAY_FALLTHRU): Define.
	* c-parser.c (objc_foreach_break_label, objc_foreach_continue_label):
	New.
	(c_parser_statement_after_labels): Adjust calls to c_finish_bc_stmt.
	(c_parser_switch_statement): Adjust break/switch context handling
	and calls to renamed functions.
	(c_parser_while_statement): Adjust break/switch context handling and
	build a WHILE_STMT.
	(c_parser_do_statement): Ditto, with DO_STMT respectively.
	(c_parser_for_statement): Ditto, with FOR_STMT respectively.
	(c_parser_omp_for_loop): Adjust break/switch context handling.
	* c-tree.h (c_break_label, c_cont_label): Delete.
	(IN_SWITCH_STMT, IN_ITERATION_STMT): Define.
	(IN_OMP_BLOCK, IN_OMP_FOR, IN_OBJC_FOREACH): Define.
	(in_statement, switch_statement_break_seen_p): Declare.
	(c_start_case, c_finish_case): Renamed to...
	(c_start_switch, c_finish_switch).
	(c_finish_bc_stmt): Adjust arguments.
	* c-typeck.c (build_function_call_vec): Don't try to print
	statements with %qE format.
	(struct c_switch):  Rename switch_expr field to switch_stmt.
	Add break_stmt_seen_p field.
	(c_start_case): Rename to c_start_switch.  Build a SWITCH_STMT
	instead of a SWITCH_EXPR.  Update for changes to struct c_switch.
	(do_case): Update for changes to struct c_switch.
	(c_finish_case): Rename to c_finish_switch.  Update for changes to
	struct c_switch and change of representation from SWITCH_EXPR to
	SWITCH_STMT.
	(c_finish_loop): Delete.
	(c_finish_bc_stmt): Update to reflect changes to break/continue
	state representation.  Build a BREAK_STMT or CONTINUE_STMT instead
	of a GOTO_EXPR except for objc foreach loops.

	gcc/objc
	* objc-act.c (objc_start_method_definition): Update to reflect
	changes to break/continue state bookkeeping in C front end.

	gcc/testsuite/
	* gcc.dg/gomp/block-7.c: Update expected error message wording.

Author: SandraLoosemore

gcc/c/c-decl.c

@@ -112,9 +112,9 @@ struct obstack parser_obstack;
 
 static GTY(()) struct stmt_tree_s c_stmt_tree;
 
-/* State saving variables.  */
-tree c_break_label;
-tree c_cont_label;
+/* Zero if we are not in an iteration or switch statement, otherwise
+   a bitmask.  See bitmask definitions in c-tree.h.  */
+unsigned char in_statement;
 
 /* A list of decls to be made automatically visible in each file scope.  */
 static GTY(()) tree visible_builtins;
@@ -9163,10 +9163,8 @@ start_function (struct c_declspecs *declspecs, struct c_declarator *declarator,
   warn_about_return_type = 0;
   c_switch_stack = NULL;
 
-  /* Indicate no valid break/continue context by setting these variables
-     to some non-null, non-label value.  We'll notice and emit the proper
-     error message in c_finish_bc_stmt.  */
-  c_break_label = c_cont_label = size_zero_node;
+  /* Indicate no valid break/continue context.  */
+  in_statement = 0;
 
   decl1 = grokdeclarator (declarator, declspecs, FUNCDEF, true, NULL,
 			  &attributes, NULL, NULL, DEPRECATED_NORMAL);
@@ -10167,8 +10165,7 @@ c_push_function_context (void)
 
   p->base.x_stmt_tree = c_stmt_tree;
   c_stmt_tree.x_cur_stmt_list = vec_safe_copy (c_stmt_tree.x_cur_stmt_list);
-  p->x_break_label = c_break_label;
-  p->x_cont_label = c_cont_label;
+  p->x_in_statement = in_statement;
   p->x_switch_stack = c_switch_stack;
   p->arg_info = current_function_arg_info;
   p->returns_value = current_function_returns_value;
@@ -10207,8 +10204,7 @@ c_pop_function_context (void)
 
   c_stmt_tree = p->base.x_stmt_tree;
   p->base.x_stmt_tree.x_cur_stmt_list = NULL;
-  c_break_label = p->x_break_label;
-  c_cont_label = p->x_cont_label;
+  in_statement = p->x_in_statement;
   c_switch_stack = p->x_switch_stack;
   current_function_arg_info = p->arg_info;
   current_function_returns_value = p->returns_value;

gcc/c/c-lang.h

@@ -51,8 +51,7 @@ struct GTY(()) lang_decl {
 
 struct GTY(()) language_function {
   struct c_language_function base;
-  tree x_break_label;
-  tree x_cont_label;
+  unsigned char x_in_statement;
   struct c_switch * GTY((skip)) x_switch_stack;
   struct c_arg_info * GTY((skip)) arg_info;
   int returns_value;

gcc/c/c-objc-common.h

@@ -56,6 +56,8 @@ along with GCC; see the file COPYING3.  If not see
 #define LANG_HOOKS_TYPES_COMPATIBLE_P c_types_compatible_p
 #undef LANG_HOOKS_MISSING_NORETURN_OK_P
 #define LANG_HOOKS_MISSING_NORETURN_OK_P c_missing_noreturn_ok_p
+#undef LANG_HOOKS_BLOCK_MAY_FALLTHRU
+#define LANG_HOOKS_BLOCK_MAY_FALLTHRU c_block_may_fallthru
 #undef  LANG_HOOKS_BUILTIN_FUNCTION
 #define LANG_HOOKS_BUILTIN_FUNCTION c_builtin_function
 #undef  LANG_HOOKS_BUILTIN_FUNCTION_EXT_SCOPE

gcc/c/c-parser.c

@@ -1479,6 +1479,9 @@ struct oacc_routine_data {
   location_t loc;
 };
 
+/* Used for parsing objc foreach statements.  */
+static tree objc_foreach_break_label, objc_foreach_continue_label;
+
 static bool c_parser_nth_token_starts_std_attributes (c_parser *,
 						      unsigned int);
 static tree c_parser_std_attribute_specifier_sequence (c_parser *);
@@ -6221,11 +6224,11 @@ c_parser_statement_after_labels (c_parser *parser, bool *if_p,
 	  goto expect_semicolon;
 	case RID_CONTINUE:
 	  c_parser_consume_token (parser);
-	  stmt = c_finish_bc_stmt (loc, &c_cont_label, false);
+	  stmt = c_finish_bc_stmt (loc, objc_foreach_continue_label, false);
 	  goto expect_semicolon;
 	case RID_BREAK:
 	  c_parser_consume_token (parser);
-	  stmt = c_finish_bc_stmt (loc, &c_break_label, true);
+	  stmt = c_finish_bc_stmt (loc, objc_foreach_break_label, true);
 	  goto expect_semicolon;
 	case RID_RETURN:
 	  c_parser_consume_token (parser);
@@ -6627,7 +6630,8 @@ static void
 c_parser_switch_statement (c_parser *parser, bool *if_p)
 {
   struct c_expr ce;
-  tree block, expr, body, save_break;
+  tree block, expr, body;
+  unsigned char save_in_statement;
   location_t switch_loc = c_parser_peek_token (parser)->location;
   location_t switch_cond_loc;
   gcc_assert (c_parser_next_token_is_keyword (parser, RID_SWITCH));
@@ -6653,26 +6657,18 @@ c_parser_switch_statement (c_parser *parser, bool *if_p)
       expr = error_mark_node;
       ce.original_type = error_mark_node;
     }
-  c_start_case (switch_loc, switch_cond_loc, expr, explicit_cast_p);
-  save_break = c_break_label;
-  c_break_label = NULL_TREE;
+  c_start_switch (switch_loc, switch_cond_loc, expr, explicit_cast_p);
+  save_in_statement = in_statement;
+  in_statement |= IN_SWITCH_STMT;
   location_t loc_after_labels;
   bool open_brace_p = c_parser_peek_token (parser)->type == CPP_OPEN_BRACE;
   body = c_parser_c99_block_statement (parser, if_p, &loc_after_labels);
   location_t next_loc = c_parser_peek_token (parser)->location;
   if (!open_brace_p && c_parser_peek_token (parser)->type != CPP_SEMICOLON)
     warn_for_multistatement_macros (loc_after_labels, next_loc, switch_loc,
 				    RID_SWITCH);
-  if (c_break_label)
-    {
-      location_t here = c_parser_peek_token (parser)->location;
-      tree t = build1 (LABEL_EXPR, void_type_node, c_break_label);
-      SET_EXPR_LOCATION (t, here);
-      SWITCH_BREAK_LABEL_P (c_break_label) = 1;
-      append_to_statement_list_force (t, &body);
-    }
-  c_finish_case (body, ce.original_type);
-  c_break_label = save_break;
+  c_finish_switch (body, ce.original_type);
+  in_statement = save_in_statement;
   add_stmt (c_end_compound_stmt (switch_loc, block, flag_isoc99));
   c_parser_maybe_reclassify_token (parser);
 }
@@ -6690,7 +6686,8 @@ static void
 c_parser_while_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 			  bool *if_p)
 {
-  tree block, cond, body, save_break, save_cont;
+  tree block, cond, body;
+  unsigned char save_in_statement;
   location_t loc;
   gcc_assert (c_parser_next_token_is_keyword (parser, RID_WHILE));
   token_indent_info while_tinfo
@@ -6709,19 +6706,16 @@ c_parser_while_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 		   build_int_cst (integer_type_node,
 				  annot_expr_unroll_kind),
 		   build_int_cst (integer_type_node, unroll));
-  save_break = c_break_label;
-  c_break_label = NULL_TREE;
-  save_cont = c_cont_label;
-  c_cont_label = NULL_TREE;
+  save_in_statement = in_statement;
+  in_statement = IN_ITERATION_STMT;
 
   token_indent_info body_tinfo
     = get_token_indent_info (c_parser_peek_token (parser));
 
   location_t loc_after_labels;
   bool open_brace = c_parser_next_token_is (parser, CPP_OPEN_BRACE);
   body = c_parser_c99_block_statement (parser, if_p, &loc_after_labels);
-  c_finish_loop (loc, loc, cond, UNKNOWN_LOCATION, NULL, body,
-		 c_break_label, c_cont_label, true);
+  add_stmt (build_stmt (loc, WHILE_STMT, cond, body));
   add_stmt (c_end_compound_stmt (loc, block, flag_isoc99));
   c_parser_maybe_reclassify_token (parser);
 
@@ -6733,8 +6727,7 @@ c_parser_while_statement (c_parser *parser, bool ivdep, unsigned short unroll,
     warn_for_multistatement_macros (loc_after_labels, next_tinfo.location,
 				    while_tinfo.location, RID_WHILE);
 
-  c_break_label = save_break;
-  c_cont_label = save_cont;
+  in_statement = save_in_statement;
 }
 
 /* Parse a do statement (C90 6.6.5, C99 6.8.5, C11 6.8.5).
@@ -6746,7 +6739,8 @@ c_parser_while_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 static void
 c_parser_do_statement (c_parser *parser, bool ivdep, unsigned short unroll)
 {
-  tree block, cond, body, save_break, save_cont, new_break, new_cont;
+  tree block, cond, body;
+  unsigned char save_in_statement;
   location_t loc;
   gcc_assert (c_parser_next_token_is_keyword (parser, RID_DO));
   c_parser_consume_token (parser);
@@ -6756,17 +6750,11 @@ c_parser_do_statement (c_parser *parser, bool ivdep, unsigned short unroll)
 		"suggest braces around empty body in %<do%> statement");
   block = c_begin_compound_stmt (flag_isoc99);
   loc = c_parser_peek_token (parser)->location;
-  save_break = c_break_label;
-  c_break_label = NULL_TREE;
-  save_cont = c_cont_label;
-  c_cont_label = NULL_TREE;
+  save_in_statement = in_statement;
+  in_statement = IN_ITERATION_STMT;
   body = c_parser_c99_block_statement (parser, NULL);
   c_parser_require_keyword (parser, RID_WHILE, "expected %<while%>");
-  new_break = c_break_label;
-  c_break_label = save_break;
-  new_cont = c_cont_label;
-  c_cont_label = save_cont;
-  location_t cond_loc = c_parser_peek_token (parser)->location;
+  in_statement = save_in_statement;
   cond = c_parser_paren_condition (parser);
   if (ivdep && cond != error_mark_node)
     cond = build3 (ANNOTATE_EXPR, TREE_TYPE (cond), cond,
@@ -6780,8 +6768,8 @@ c_parser_do_statement (c_parser *parser, bool ivdep, unsigned short unroll)
  		   build_int_cst (integer_type_node, unroll));
   if (!c_parser_require (parser, CPP_SEMICOLON, "expected %<;%>"))
     c_parser_skip_to_end_of_block_or_statement (parser);
-  c_finish_loop (loc, cond_loc, cond, UNKNOWN_LOCATION, NULL, body,
-		 new_break, new_cont, false);
+
+  add_stmt (build_stmt (loc, DO_STMT, cond, body));
   add_stmt (c_end_compound_stmt (loc, block, flag_isoc99));
 }
 
@@ -6848,15 +6836,15 @@ static void
 c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 			bool *if_p)
 {
-  tree block, cond, incr, save_break, save_cont, body;
+  tree block, cond, incr, body;
+  unsigned char save_in_statement;
+  tree save_objc_foreach_break_label, save_objc_foreach_continue_label;
   /* The following are only used when parsing an ObjC foreach statement.  */
   tree object_expression;
   /* Silence the bogus uninitialized warning.  */
   tree collection_expression = NULL;
   location_t loc = c_parser_peek_token (parser)->location;
   location_t for_loc = loc;
-  location_t cond_loc = UNKNOWN_LOCATION;
-  location_t incr_loc = UNKNOWN_LOCATION;
   bool is_foreach_statement = false;
   gcc_assert (c_parser_next_token_is_keyword (parser, RID_FOR));
   token_indent_info for_tinfo
@@ -6966,7 +6954,6 @@ c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
       gcc_assert (!parser->objc_could_be_foreach_context);
       if (!is_foreach_statement)
 	{
-	  cond_loc = c_parser_peek_token (parser)->location;
 	  if (c_parser_next_token_is (parser, CPP_SEMICOLON))
 	    {
 	      if (ivdep)
@@ -7007,7 +6994,7 @@ c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
       /* Parse the increment expression (the third expression in a
 	 for-statement).  In the case of a foreach-statement, this is
 	 the expression that follows the 'in'.  */
-      loc = incr_loc = c_parser_peek_token (parser)->location;
+      loc = c_parser_peek_token (parser)->location;
       if (c_parser_next_token_is (parser, CPP_CLOSE_PAREN))
 	{
 	  if (is_foreach_statement)
@@ -7033,10 +7020,17 @@ c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 	}
       parens.skip_until_found_close (parser);
     }
-  save_break = c_break_label;
-  c_break_label = NULL_TREE;
-  save_cont = c_cont_label;
-  c_cont_label = NULL_TREE;
+  save_in_statement = in_statement;
+  if (is_foreach_statement)
+    {
+      in_statement = IN_OBJC_FOREACH;
+      save_objc_foreach_break_label = objc_foreach_break_label;
+      save_objc_foreach_continue_label = objc_foreach_continue_label;
+      objc_foreach_break_label = create_artificial_label (loc);
+      objc_foreach_continue_label = create_artificial_label (loc);
+    }
+  else
+    in_statement = IN_ITERATION_STMT;
 
   token_indent_info body_tinfo
     = get_token_indent_info (c_parser_peek_token (parser));
@@ -7047,11 +7041,12 @@ c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
 
   if (is_foreach_statement)
     objc_finish_foreach_loop (for_loc, object_expression,
-			      collection_expression, body, c_break_label,
-			      c_cont_label);
+			      collection_expression, body,
+			      objc_foreach_break_label,
+			      objc_foreach_continue_label);
   else
-    c_finish_loop (for_loc, cond_loc, cond, incr_loc, incr, body,
-		   c_break_label, c_cont_label, true);
+    add_stmt (build_stmt (for_loc, FOR_STMT, NULL_TREE, cond, incr,
+			  body, NULL_TREE));
   add_stmt (c_end_compound_stmt (for_loc, block,
 				 flag_isoc99 || c_dialect_objc ()));
   c_parser_maybe_reclassify_token (parser);
@@ -7064,8 +7059,12 @@ c_parser_for_statement (c_parser *parser, bool ivdep, unsigned short unroll,
     warn_for_multistatement_macros (loc_after_labels, next_tinfo.location,
 				    for_tinfo.location, RID_FOR);
 
-  c_break_label = save_break;
-  c_cont_label = save_cont;
+  in_statement = save_in_statement;
+  if (is_foreach_statement)
+    {
+      objc_foreach_break_label = save_objc_foreach_break_label;
+      objc_foreach_continue_label = save_objc_foreach_continue_label;
+    }
 }
 
 /* Parse an asm statement, a GNU extension.  This is a full-blown asm
@@ -18038,7 +18037,8 @@ static tree
 c_parser_omp_for_loop (location_t loc, c_parser *parser, enum tree_code code,
 		       tree clauses, tree *cclauses, bool *if_p)
 {
-  tree decl, cond, incr, save_break, save_cont, body, init, stmt, cl;
+  tree decl, cond, incr, body, init, stmt, cl;
+  unsigned char save_in_statement;
   tree declv, condv, incrv, initv, ret = NULL_TREE;
   tree pre_body = NULL_TREE, this_pre_body;
   tree ordered_cl = NULL_TREE;
@@ -18106,6 +18106,11 @@ c_parser_omp_for_loop (location_t loc, c_parser *parser, enum tree_code code,
   for_loc = c_parser_peek_token (parser)->location;
   c_parser_consume_token (parser);
 
+  /* Forbid break/continue in the loop initializer, condition, and
+     increment expressions.  */
+  save_in_statement = in_statement;
+  in_statement = IN_OMP_BLOCK;
+
   for (i = 0; i < count; i++)
     {
       int bracecount = 0;
@@ -18279,10 +18284,7 @@ c_parser_omp_for_loop (location_t loc, c_parser *parser, enum tree_code code,
   if (nbraces)
     if_p = NULL;
 
-  save_break = c_break_label;
-  c_break_label = size_one_node;
-  save_cont = c_cont_label;
-  c_cont_label = NULL_TREE;
+  in_statement = IN_OMP_FOR;
   body = push_stmt_list ();
 
   if (inscan)
@@ -18296,16 +18298,9 @@ c_parser_omp_for_loop (location_t loc, c_parser *parser, enum tree_code code,
     }
   else
     add_stmt (c_parser_c99_block_statement (parser, if_p));
-  if (c_cont_label)
-    {
-      tree t = build1 (LABEL_EXPR, void_type_node, c_cont_label);
-      SET_EXPR_LOCATION (t, loc);
-      add_stmt (t);
-    }
 
   body = pop_stmt_list (body);
-  c_break_label = save_break;
-  c_cont_label = save_cont;
+  in_statement = save_in_statement;
 
   while (nbraces)
     {

gcc/c/c-tree.h

@@ -547,8 +547,19 @@ extern void gen_aux_info_record (tree, int, int, int);
 struct c_spot_bindings;
 class c_struct_parse_info;
 extern struct obstack parser_obstack;
-extern tree c_break_label;
-extern tree c_cont_label;
+/* Set to IN_ITERATION_STMT if parsing an iteration-statement,
+   to IN_OMP_BLOCK if parsing OpenMP structured block and
+   IN_OMP_FOR if parsing OpenMP loop.  If parsing a switch statement,
+   this is bitwise ORed with IN_SWITCH_STMT, unless parsing an
+   iteration-statement, OpenMP block or loop within that switch.  */
+#define IN_SWITCH_STMT		1
+#define IN_ITERATION_STMT	2
+#define IN_OMP_BLOCK		4
+#define IN_OMP_FOR		8
+#define IN_OBJC_FOREACH		16
+extern unsigned char in_statement;
+
+extern bool switch_statement_break_seen_p;
 
 extern bool global_bindings_p (void);
 extern tree pushdecl (tree);
@@ -714,8 +725,8 @@ extern void process_init_element (location_t, struct c_expr, bool,
 extern tree build_compound_literal (location_t, tree, tree, bool,
 				    unsigned int);
 extern void check_compound_literal_type (location_t, struct c_type_name *);
-extern tree c_start_case (location_t, location_t, tree, bool);
-extern void c_finish_case (tree, tree);
+extern tree c_start_switch (location_t, location_t, tree, bool);
+extern void c_finish_switch (tree, tree);
 extern tree build_asm_expr (location_t, tree, tree, tree, tree, tree, bool,
 			    bool);
 extern tree build_asm_stmt (bool, tree);
@@ -730,7 +741,7 @@ extern tree c_finish_stmt_expr (location_t, tree);
 extern tree c_process_expr_stmt (location_t, tree);
 extern tree c_finish_expr_stmt (location_t, tree);
 extern tree c_finish_return (location_t, tree, tree);
-extern tree c_finish_bc_stmt (location_t, tree *, bool);
+extern tree c_finish_bc_stmt (location_t, tree, bool);
 extern tree c_finish_goto_label (location_t, tree);
 extern tree c_finish_goto_ptr (location_t, tree);
 extern tree c_expr_to_decl (tree, bool *, bool *);