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

2020-08-12  Sandra Loosemore  <sandra@codesourcery.com>

	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.

1 files changed, 7 insertions, 11 deletions

diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
index 190c00b..8204db2 100644
--- a/gcc/c/c-decl.c
+++ b/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;