IR tracer for try statements.

pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library tree_ir_tracer;
 
 import 'dart:async' show EventSink;
 import '../tracer.dart';
 import 'tree_ir_nodes.dart';
 import 'optimization/optimization.dart';
 
 class Block {
   Label label;
   int index;
   /// Mixed list of [Statement] and [Block].
   /// A [Block] represents a synthetic goto statement.
   final List statements = [];
   final List<Block> predecessors = <Block>[];
   final List<Block> successors = <Block>[];
 
+  /// The catch block associated with the immediately enclosing try block or
+  /// `null` if not inside a try block.
+  Block catcher;
+
   String get name => 'B$index';
 
   Block([this.label]);
 
   void addEdgeTo(Block successor) {
     successors.add(successor);
     successor.predecessors.add(this);
   }
 }
 
 class BlockCollector extends StatementVisitor {
   // Accumulate a list of blocks.  The current block is the last block in
   // the list.
   final List<Block> blocks = [new Block()..index = 0];
 
   // Map tree [Label]s (break or continue targets) and [Statement]s
   // (if targets) to blocks.
   final Map<Label, Block> breakTargets = <Label, Block>{};
   final Map<Label, Block> continueTargets = <Label, Block>{};
-  final Map<Statement, Block> ifTargets = <Statement, Block>{};
+  final Map<Statement, Block> substatements = <Statement, Block>{};
+
+  Block catcher;
 
   void _addStatement(Statement statement) {
     blocks.last.statements.add(statement);
   }
   void _addGotoStatement(Block target) {
     blocks.last.statements.add(target);
   }
 
   void _addBlock(Block block) {
     block.index = blocks.length;
+    block.catcher = catcher;
     blocks.add(block);
   }
 
   void collect(ExecutableDefinition node) {
     if (node.body != null) {
       if (node is ConstructorDefinition) {
         for (Initializer initializer in node.initializers) {
           if (initializer is FieldInitializer) {
             visitStatement(initializer.body);
           }
@@ skipping 27 matching lines @@
 
   visitContinue(Continue node) {
     _addStatement(node);
     blocks.last.addEdgeTo(continueTargets[node.target]);
   }
 
   visitIf(If node) {
     _addStatement(node);
     Block thenTarget = new Block();
     Block elseTarget = new Block();
-    ifTargets[node.thenStatement] = thenTarget;
-    ifTargets[node.elseStatement] = elseTarget;
+    substatements[node.thenStatement] = thenTarget;
+    substatements[node.elseStatement] = elseTarget;
     blocks.last.addEdgeTo(thenTarget);
     blocks.last.addEdgeTo(elseTarget);
     _addBlock(thenTarget);
     visitStatement(node.thenStatement);
     _addBlock(elseTarget);
     visitStatement(node.elseStatement);
   }
 
   visitWhileTrue(WhileTrue node) {
     Block continueTarget = new Block();
@@ skipping 20 matching lines @@
     whileBlock.addEdgeTo(bodyBlock);
     whileBlock.addEdgeTo(nextBlock);
 
     continueTargets[node.label] = bodyBlock;
     _addBlock(bodyBlock);
     visitStatement(node.body);
 
     _addBlock(nextBlock);
     visitStatement(node.next);
 
-    ifTargets[node.body] = bodyBlock;
-    ifTargets[node.next] = nextBlock;
+    substatements[node.body] = bodyBlock;
+    substatements[node.next] = nextBlock;
   }
 
   visitTry(Try node) {
-    // It's not obvious how we want to represent try statements here.
-    // TODO(kmillikin).
+    _addStatement(node);
+    Block tryBlock = new Block();
+    Block catchBlock = new Block();
+
+    Block oldCatcher = catcher;
+    catcher = catchBlock;
+    _addBlock(tryBlock);
+    visitStatement(node.tryBody);
+    catcher = oldCatcher;
+
+    _addBlock(catchBlock);
+    visitStatement(node.catchBody);
+
+    substatements[node.tryBody] = tryBlock;
+    substatements[node.catchBody] = catchBlock;
   }
 
   visitExpressionStatement(ExpressionStatement node) {
     _addStatement(node);
     visitStatement(node.next);
   }
 
   visitFunctionDeclaration(FunctionDeclaration node) {
     _addStatement(node);
     visitStatement(node.next);
@@ skipping 48 matching lines @@
         tag("locals", () {
           printProperty("size", 0);
           printProperty("method", "None");
         });
       });
       tag("HIR", () {
         if (block.label != null) {
           printStatement(null,
               "Label ${block.name}, useCount=${block.label.useCount}");
         }
+        if (block.catcher != null) {
+          printStatement(null, 'Catch exceptions at ${block.catcher.name}');
+        }
         block.statements.forEach(visitBlockMember);
       });
     });
   }
 
   void visitBlockMember(member) {
     if (member is Block) {
       printStatement(null, "goto block B${member.name}");
     } else {
       assert(member is Statement);
@@ skipping 31 matching lines @@
     printStatement(null, "break ${collector.breakTargets[node.target].name}");
   }
 
   visitContinue(Continue node) {
     printStatement(null,
         "continue ${collector.continueTargets[node.target].name}");
   }
 
   visitIf(If node) {
     String condition = expr(node.condition);
-    String thenTarget = collector.ifTargets[node.thenStatement].name;
-    String elseTarget = collector.ifTargets[node.elseStatement].name;
+    String thenTarget = collector.substatements[node.thenStatement].name;
+    String elseTarget = collector.substatements[node.elseStatement].name;
     printStatement(null, "if $condition then $thenTarget else $elseTarget");
   }
 
   visitWhileTrue(WhileTrue node) {
     printStatement(null, "while true do");
   }
 
   visitWhileCondition(WhileCondition node) {
-    String bodyTarget = collector.ifTargets[node.body].name;
-    String nextTarget = collector.ifTargets[node.next].name;
+    String bodyTarget = collector.substatements[node.body].name;
+    String nextTarget = collector.substatements[node.next].name;
     printStatement(null, "while ${expr(node.condition)}");
     printStatement(null, "do $bodyTarget");
     printStatement(null, "then $nextTarget" );
   }
 
   visitTry(Try node) {
-    // It's not obvious how we want to represent try statements here.
-    // TODO(kmillikin).
+    String tryTarget = collector.substatements[node.tryBody].name;
+    String catchParams = node.catchParameters.map(names.varName).join(',');
+    String catchTarget = collector.substatements[node.catchBody].name;
+    printStatement(null, 'try $tryTarget catch($catchParams) $catchTarget');
   }
 
   visitExpressionStatement(ExpressionStatement node) {
     printStatement(null, expr(node.expression));
   }
 
   visitFunctionDeclaration(FunctionDeclaration node) {
     printStatement(null, 'function ${node.definition.element.name}');
   }
 
@@ skipping 188 matching lines @@
       String prefix = v.element == null ? 'v' : '${v.element.name}_';
       while (name == null || _usedNames.contains(name)) {
         name = "$prefix${_counter++}";
       }
       _names[v] = name;
       _usedNames.add(name);
     }
     return name;
   }
 }