analyzer: Break cyclic references of BasicBlock

https://bugzilla.gnome.org/show_bug.cgi?id=794979

2 files changed, 41 insertions, 17 deletions

diff --git a/vala/valabasicblock.vala b/vala/valabasicblock.vala
index f1c3ea810..759bb9ce0 100644
--- a/vala/valabasicblock.vala
+++ b/vala/valabasicblock.vala
@@ -31,12 +31,12 @@ public class Vala.BasicBlock {
 
 	// control flow graph
 	private List<weak BasicBlock> predecessors = new ArrayList<weak BasicBlock> ();
-	private List<BasicBlock> successors = new ArrayList<BasicBlock> ();
+	private List<weak BasicBlock> successors = new ArrayList<weak BasicBlock> ();
 
 	// dominator tree
-	public BasicBlock parent { get; private set; }
-	List<BasicBlock> children = new ArrayList<BasicBlock> ();
-	Set<BasicBlock> df = new HashSet<BasicBlock> ();
+	public weak BasicBlock parent { get; private set; }
+	List<weak BasicBlock> children = new ArrayList<weak BasicBlock> ();
+	Set<weak BasicBlock> df = new HashSet<weak BasicBlock> ();
 
 	Set<PhiFunction> phi_functions = new HashSet<PhiFunction> ();
 
@@ -73,7 +73,7 @@ public class Vala.BasicBlock {
 		return predecessors;
 	}
 
-	public List<BasicBlock> get_successors () {
+	public List<weak BasicBlock> get_successors () {
 		return successors;
 	}
 
@@ -82,7 +82,7 @@ public class Vala.BasicBlock {
 		block.parent = this;
 	}
 
-	public List<BasicBlock> get_children () {
+	public List<weak BasicBlock> get_children () {
 		return children;
 	}
 
@@ -90,7 +90,7 @@ public class Vala.BasicBlock {
 		df.add (block);
 	}
 
-	public Set<BasicBlock> get_dominator_frontier () {
+	public Set<weak BasicBlock> get_dominator_frontier () {
 		return df;
 	}
 
diff --git a/vala/valaflowanalyzer.vala b/vala/valaflowanalyzer.vala
index 7f362783e..ff7c03edc 100644
--- a/vala/valaflowanalyzer.vala
+++ b/vala/valaflowanalyzer.vala
@@ -89,6 +89,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 	private BasicBlock current_block;
 	private bool unreachable_reported;
 	private List<JumpTarget> jump_stack = new ArrayList<JumpTarget> ();
+	private Set<BasicBlock> all_basic_blocks;
 
 	// check_variables
 	Map<Symbol, List<Variable>> var_map;
@@ -105,6 +106,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 	 */
 	public void analyze (CodeContext context) {
 		this.context = context;
+		all_basic_blocks = new HashSet<BasicBlock> ();
 
 		/* we're only interested in non-pkg source files */
 		var source_files = context.get_source_files ();
@@ -114,6 +116,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 			}
 		}
 
+		all_basic_blocks = null;
 		this.context = null;
 	}
 
@@ -194,8 +197,11 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 		}
 
 		m.entry_block = new BasicBlock.entry ();
+		all_basic_blocks.add (m.entry_block);
 		m.return_block = new BasicBlock ();
+		all_basic_blocks.add (m.return_block);
 		m.exit_block = new BasicBlock.exit ();
+		all_basic_blocks.add (m.exit_block);
 
 		m.return_block.connect (m.exit_block);
 
@@ -211,6 +217,8 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 		}
 
 		current_block = new BasicBlock ();
+		all_basic_blocks.add (current_block);
+
 		m.entry_block.connect (current_block);
 		current_block.add_node (m);
 
@@ -256,7 +264,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 			return;
 		}
 		current.postorder_visited = true;
-		foreach (BasicBlock succ in current.get_successors ()) {
+		foreach (weak BasicBlock succ in current.get_successors ()) {
 			depth_first_traverse (succ, list);
 		}
 		current.postorder_number = list.size;
@@ -279,7 +287,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 				// new immediate dominator
 				BasicBlock new_idom = null;
 				bool first = true;
-				foreach (BasicBlock pred in block.get_predecessors ()) {
+				foreach (weak BasicBlock pred in block.get_predecessors ()) {
 					if (idoms[pred.postorder_number] != null) {
 						if (first) {
 							new_idom = pred;
@@ -322,15 +330,15 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 		for (int i = block_list.size - 1; i >= 0; i--) {
 			var block = block_list[i];
 
-			foreach (BasicBlock succ in block.get_successors ()) {
+			foreach (weak BasicBlock succ in block.get_successors ()) {
 				// if idom(succ) != block
 				if (succ.parent != block) {
 					block.add_dominator_frontier (succ);
 				}
 			}
 
-			foreach (BasicBlock child in block.get_children ()) {
-				foreach (BasicBlock child_frontier in child.get_dominator_frontier ()) {
+			foreach (weak BasicBlock child in block.get_children ()) {
+				foreach (weak BasicBlock child_frontier in child.get_dominator_frontier ()) {
 					// if idom(child_frontier) != block
 					if (child_frontier.parent != block) {
 						block.add_dominator_frontier (child_frontier);
@@ -475,9 +483,9 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 			}
 		}
 
-		foreach (BasicBlock succ in block.get_successors ()) {
+		foreach (weak BasicBlock succ in block.get_successors ()) {
 			int j = 0;
-			foreach (BasicBlock pred in succ.get_predecessors ()) {
+			foreach (weak BasicBlock pred in succ.get_predecessors ()) {
 				if (pred == block) {
 					break;
 				}
@@ -492,7 +500,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 			}
 		}
 
-		foreach (BasicBlock child in block.get_children ()) {
+		foreach (weak BasicBlock child in block.get_children ()) {
 			check_block_variables (child);
 		}
 
@@ -620,6 +628,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 			mark_unreachable ();
 		} else {
 			current_block = new BasicBlock ();
+			all_basic_blocks.add (current_block);
 			last_block.connect (current_block);
 		}
 		stmt.true_statement.accept (this);
@@ -630,6 +639,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 			mark_unreachable ();
 		} else {
 			current_block = new BasicBlock ();
+			all_basic_blocks.add (current_block);
 			last_block.connect (current_block);
 		}
 		if (stmt.false_statement != null) {
@@ -641,6 +651,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 		// reachable?
 		if (last_true_block != null || last_false_block != null) {
 			current_block = new BasicBlock ();
+			all_basic_blocks.add (current_block);
 			if (last_true_block != null) {
 				last_true_block.connect (current_block);
 			}
@@ -656,6 +667,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 		}
 
 		var after_switch_block = new BasicBlock ();
+		all_basic_blocks.add (after_switch_block);
 		jump_stack.add (new JumpTarget.break_target (after_switch_block));
 
 		// condition
@@ -668,6 +680,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 
 		foreach (SwitchSection section in stmt.get_sections ()) {
 			current_block = new BasicBlock ();
+			all_basic_blocks.add (current_block);
 			condition_block.connect (current_block);
 			foreach (Statement section_stmt in section.get_statements ()) {
 				section_stmt.accept (this);
@@ -709,8 +722,10 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 		}
 
 		var loop_block = new BasicBlock ();
+		all_basic_blocks.add (loop_block);
 		jump_stack.add (new JumpTarget.continue_target (loop_block));
 		var after_loop_block = new BasicBlock ();
+		all_basic_blocks.add (after_loop_block);
 		jump_stack.add (new JumpTarget.break_target (after_loop_block));
 
 		// loop block
@@ -748,8 +763,10 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 		handle_errors (stmt.collection);
 
 		var loop_block = new BasicBlock ();
+		all_basic_blocks.add (loop_block);
 		jump_stack.add (new JumpTarget.continue_target (loop_block));
 		var after_loop_block = new BasicBlock ();
+		all_basic_blocks.add (after_loop_block);
 		jump_stack.add (new JumpTarget.break_target (after_loop_block));
 
 		// loop block
@@ -893,6 +910,7 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 			// normal control flow
 			if (!always_fail) {
 				current_block = new BasicBlock ();
+				all_basic_blocks.add (current_block);
 				last_block.connect (current_block);
 			}
 		}
@@ -922,14 +940,17 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 
 		var before_try_block = current_block;
 		var after_try_block = new BasicBlock ();
+		all_basic_blocks.add (after_try_block);
 
 		BasicBlock finally_block = null;
 		if (stmt.finally_body != null) {
 			finally_block = new BasicBlock ();
+			all_basic_blocks.add (finally_block);
 			current_block = finally_block;
 
 			// trap all forbidden jumps
 			var invalid_block = new BasicBlock ();
+			all_basic_blocks.add (invalid_block);
 			jump_stack.add (new JumpTarget.any_target (invalid_block));
 
 			stmt.finally_body.accept (this);
@@ -950,11 +971,14 @@ public class Vala.FlowAnalyzer : CodeVisitor {
 		var catch_clauses = stmt.get_catch_clauses ();
 		for (int i = catch_clauses.size - 1; i >= 0; i--) {
 			var catch_clause = catch_clauses[i];
+			var error_block = new BasicBlock ();
+			all_basic_blocks.add (error_block);
+
 			if (catch_clause.error_type != null) {
 				var error_type = (ErrorType) catch_clause.error_type;
-				jump_stack.add (new JumpTarget.error_target (new BasicBlock (), catch_clause, catch_clause.error_type.data_type as ErrorDomain, error_type.error_code, null));
+				jump_stack.add (new JumpTarget.error_target (error_block, catch_clause, catch_clause.error_type.data_type as ErrorDomain, error_type.error_code, null));
 			} else {
-				jump_stack.add (new JumpTarget.error_target (new BasicBlock (), catch_clause, null, null, null));
+				jump_stack.add (new JumpTarget.error_target (error_block, catch_clause, null, null, null));
 			}
 		}