--- /dev/null
+/* valacfgbuilder.vala
+ *
+ * Copyright (C) 2008 Jürg Billeter
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Author:
+ * Jürg Billeter <j@bitron.ch>
+ */
+
+using GLib;
+using Gee;
+
+/**
+ * Code visitor building the control flow graph.
+ */
+public class Vala.CFGBuilder : CodeVisitor {
+ private CodeContext context;
+ private BasicBlock current_block;
+ private bool unreachable_reported;
+ private Method current_method;
+ private Gee.List<BasicBlock> breakable_stack = new ArrayList<BasicBlock> ();
+ private Gee.List<BasicBlock> continuable_stack = new ArrayList<BasicBlock> ();
+
+ public CFGBuilder () {
+ }
+
+ /**
+ * Build control flow graph in the specified context.
+ *
+ * @param context a code context
+ */
+ public void build_cfg (CodeContext! context) {
+ this.context = context;
+
+ /* we're only interested in non-pkg source files */
+ var source_files = context.get_source_files ();
+ foreach (SourceFile file in source_files) {
+ if (!file.pkg) {
+ file.accept (this);
+ }
+ }
+ }
+
+ public override void visit_source_file (SourceFile! source_file) {
+ source_file.accept_children (this);
+ }
+
+ public override void visit_class (Class! cl) {
+ cl.accept_children (this);
+ }
+
+ public override void visit_struct (Struct! st) {
+ st.accept_children (this);
+ }
+
+ public override void visit_interface (Interface! iface) {
+ iface.accept_children (this);
+ }
+
+ public override void visit_enum (Enum! en) {
+ en.accept_children (this);
+ }
+
+ public override void visit_method (Method! m) {
+ if (m.body == null) {
+ return;
+ }
+
+ var old_method = current_method;
+ current_method = m;
+
+ m.entry_block = new BasicBlock.entry ();
+ m.exit_block = new BasicBlock.exit ();
+
+ current_block = new BasicBlock ();
+ m.entry_block.connect (current_block);
+
+ m.accept_children (this);
+
+ if (current_block != null) {
+ // end of method body reachable
+
+ if (!(m.return_type is VoidType)) {
+ Report.error (m.source_reference, "missing return statement at end of method body");
+ m.error = true;
+ }
+
+ current_block.connect (m.exit_block);
+ }
+
+ current_method = old_method;
+ }
+
+ public override void visit_block (Block! b) {
+ b.accept_children (this);
+ }
+
+ public override void visit_declaration_statement (DeclarationStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ current_block.add_node (stmt);
+ }
+
+ public override void visit_expression_statement (ExpressionStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ current_block.add_node (stmt);
+ }
+
+ public override void visit_if_statement (IfStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ // condition
+ current_block.add_node (stmt.condition);
+
+ // true block
+ var last_block = current_block;
+ current_block = new BasicBlock ();
+ last_block.connect (current_block);
+ stmt.true_statement.accept (this);
+
+ // false block
+ var last_true_block = current_block;
+ current_block = new BasicBlock ();
+ last_block.connect (current_block);
+ if (stmt.false_statement != null) {
+ stmt.false_statement.accept (this);
+ }
+
+ // after if/else
+ var last_false_block = current_block;
+ // reachable?
+ if (last_true_block != null || last_false_block != null) {
+ current_block = new BasicBlock ();
+ if (last_true_block != null) {
+ last_true_block.connect (current_block);
+ }
+ if (last_false_block != null) {
+ last_false_block.connect (current_block);
+ }
+ }
+ }
+
+ public override void visit_while_statement (WhileStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ var condition_block = new BasicBlock ();
+ continuable_stack.add (condition_block);
+ var after_loop_block = new BasicBlock ();
+ breakable_stack.add (after_loop_block);
+
+ // condition
+ var last_block = current_block;
+ last_block.connect (condition_block);
+ condition_block.add_node (stmt.condition);
+
+ // loop block
+ current_block = new BasicBlock ();
+ condition_block.connect (current_block);
+ stmt.body.accept (this);
+ // end of loop block reachable?
+ if (current_block != null) {
+ current_block.connect (condition_block);
+ }
+
+ // after loop
+ condition_block.connect (after_loop_block);
+ current_block = after_loop_block;
+
+ continuable_stack.remove_at (continuable_stack.size - 1);
+ breakable_stack.remove_at (breakable_stack.size - 1);
+ }
+
+ public override void visit_do_statement (DoStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ var condition_block = new BasicBlock ();
+ continuable_stack.add (condition_block);
+ var after_loop_block = new BasicBlock ();
+ breakable_stack.add (after_loop_block);
+
+ // loop block
+ var last_block = current_block;
+ var loop_block = new BasicBlock ();
+ last_block.connect (loop_block);
+ current_block = loop_block;
+ stmt.body.accept (this);
+
+ // condition
+ // reachable?
+ if (current_block != null || condition_block.get_predecessors ().size > 0) {
+ if (current_block != null) {
+ last_block = current_block;
+ last_block.connect (condition_block);
+ }
+ condition_block.add_node (stmt.condition);
+ condition_block.connect (loop_block);
+ current_block = condition_block;
+ }
+
+ // after loop
+ // reachable?
+ if (current_block != null || after_loop_block.get_predecessors ().size > 0) {
+ if (current_block != null) {
+ last_block = current_block;
+ last_block.connect (after_loop_block);
+ }
+ current_block = after_loop_block;
+ }
+
+ continuable_stack.remove_at (continuable_stack.size - 1);
+ breakable_stack.remove_at (breakable_stack.size - 1);
+ }
+
+ public override void visit_for_statement (ForStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ // initializer
+ foreach (Expression init_expr in stmt.get_initializer ()) {
+ current_block.add_node (init_expr);
+ }
+
+ var iterator_block = new BasicBlock ();
+ continuable_stack.add (iterator_block);
+ var after_loop_block = new BasicBlock ();
+ breakable_stack.add (after_loop_block);
+
+ // condition
+ var condition_block = new BasicBlock ();
+ current_block.connect (condition_block);
+ condition_block.add_node (stmt.condition);
+
+ // loop block
+ current_block = new BasicBlock ();
+ condition_block.connect (current_block);
+ stmt.body.accept (this);
+
+ // iterator
+ // reachable?
+ if (current_block != null || iterator_block.get_predecessors ().size > 0) {
+ if (current_block != null) {
+ current_block.connect (iterator_block);
+ }
+ foreach (Expression it_expr in stmt.get_iterator ()) {
+ iterator_block.add_node (it_expr);
+ }
+ iterator_block.connect (condition_block);
+ }
+
+ // after loop
+ condition_block.connect (after_loop_block);
+ current_block = after_loop_block;
+
+ continuable_stack.remove_at (continuable_stack.size - 1);
+ breakable_stack.remove_at (breakable_stack.size - 1);
+ }
+
+ public override void visit_foreach_statement (ForeachStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ var loop_block = new BasicBlock ();
+ continuable_stack.add (loop_block);
+ var after_loop_block = new BasicBlock ();
+ breakable_stack.add (after_loop_block);
+
+ // loop block
+ var last_block = current_block;
+ last_block.connect (loop_block);
+ current_block = loop_block;
+ stmt.body.accept (this);
+ if (current_block != null) {
+ current_block.connect (loop_block);
+ }
+
+ // after loop
+ last_block.connect (after_loop_block);
+ if (current_block != null) {
+ current_block.connect (after_loop_block);
+ }
+ current_block = after_loop_block;
+
+ continuable_stack.remove_at (continuable_stack.size - 1);
+ breakable_stack.remove_at (breakable_stack.size - 1);
+ }
+
+ public override void visit_break_statement (BreakStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ current_block.add_node (stmt);
+ current_block.connect (top_breakable ());
+ current_block = null;
+ unreachable_reported = false;
+ }
+
+ public override void visit_continue_statement (ContinueStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ current_block.add_node (stmt);
+ current_block.connect (top_continuable ());
+ current_block = null;
+ unreachable_reported = false;
+ }
+
+ public override void visit_return_statement (ReturnStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ current_block.add_node (stmt);
+ current_block.connect (current_method.exit_block);
+ current_block = null;
+ unreachable_reported = false;
+ }
+
+ public override void visit_throw_statement (ThrowStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ current_block.add_node (stmt);
+ // TODO connect to catch blocks instead of exit block if appropriate
+ current_block.connect (current_method.exit_block);
+ current_block = null;
+ unreachable_reported = false;
+ }
+
+ public override void visit_try_statement (TryStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ stmt.body.accept (this);
+
+ // TODO exceptional control flow
+ }
+
+ public override void visit_lock_statement (LockStatement! stmt) {
+ if (unreachable (stmt)) {
+ return;
+ }
+
+ stmt.body.accept (this);
+ }
+
+ private bool unreachable (CodeNode node) {
+ if (current_block == null) {
+ if (!unreachable_reported) {
+ Report.warning (node.source_reference, "unreachable code detected");
+ unreachable_reported = true;
+ }
+ return true;
+ }
+
+ return false;
+ }
+
+ private BasicBlock top_breakable () {
+ return breakable_stack.get (breakable_stack.size - 1);
+ }
+
+ private BasicBlock top_continuable () {
+ return continuable_stack.get (continuable_stack.size - 1);
+ }
+}
projects / thirdparty / vala.git / commitdiff
