[fullcode] Change fullcode to compile finally using the token approach.

src/compiler/ast-graph-builder.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/ast-graph-builder.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
@@ skipping 188 matching lines @@
   int context_length() const { return context_length_; }
   int stack_height() const { return stack_height_; }
 
  private:
   AstGraphBuilder* builder_;
   ControlScope* outer_;
   int context_length_;
   int stack_height_;
 };
 
-
 // Helper class for a try-finally control scope. It can record intercepted
 // control-flow commands that cause entry into a finally-block, and re-apply
 // them after again leaving that block. Special tokens are used to identify
 // paths going through the finally-block to dispatch after leaving the block.
 class AstGraphBuilder::ControlScope::DeferredCommands : public ZoneObject {
  public:
   explicit DeferredCommands(AstGraphBuilder* owner)
-      : owner_(owner), deferred_(owner->local_zone()) {}
+      : owner_(owner),
+        deferred_(owner->local_zone()),
+        return_token_(nullptr),
+        throw_token_(nullptr) {}
 
   // One recorded control-flow command.
   struct Entry {
     Command command;       // The command type being applied on this path.
     Statement* statement;  // The target statement for the command or {nullptr}.
     Node* token;           // A token identifying this particular path.
   };
 
   // Records a control-flow command while entering the finally-block. This also
   // generates a new dispatch token that identifies one particular path.
   Node* RecordCommand(Command cmd, Statement* stmt, Node* value) {
-    Node* token = NewPathTokenForDeferredCommand();
+    Node* token = nullptr;
+    switch (cmd) {
+      case CMD_BREAK:
+      case CMD_CONTINUE:
+        token = WrapToken(dispenser_.GetBreakContinueToken());
+        break;
+      case CMD_THROW:
+        if (throw_token_) return throw_token_;
+        token = WrapToken(TokenDispenserForFinally::kThrowToken);
+        throw_token_ = token;
+        break;
+      case CMD_RETURN:
+        if (return_token_) return return_token_;
+        token = WrapToken(TokenDispenserForFinally::kReturnToken);
+        return_token_ = token;
+        break;
+    }
+    DCHECK_NOT_NULL(token);
     deferred_.push_back({cmd, stmt, token});
     return token;
   }
 
   // Returns the dispatch token to be used to identify the implicit fall-through
   // path at the end of a try-block into the corresponding finally-block.
   Node* GetFallThroughToken() { return NewPathTokenForImplicitFallThrough(); }
 
   // Applies all recorded control-flow commands after the finally-block again.
   // This generates a dynamic dispatch on the token from the entry point.
   void ApplyDeferredCommands(Node* token, Node* value) {
     SwitchBuilder dispatch(owner_, static_cast<int>(deferred_.size()));
     dispatch.BeginSwitch();
     for (size_t i = 0; i < deferred_.size(); ++i) {
       Node* condition = NewPathDispatchCondition(token, deferred_[i].token);
       dispatch.BeginLabel(static_cast<int>(i), condition);
       dispatch.EndLabel();
     }
     for (size_t i = 0; i < deferred_.size(); ++i) {
       dispatch.BeginCase(static_cast<int>(i));
       owner_->execution_control()->PerformCommand(
           deferred_[i].command, deferred_[i].statement, value);
       dispatch.EndCase();
     }
     dispatch.EndSwitch();
   }
 
  protected:
-  Node* NewPathTokenForDeferredCommand() {
-    return owner_->jsgraph()->Constant(static_cast<int>(deferred_.size()));
+  Node* WrapToken(int token_id) {

[Michael Starzinger, 2016/02/05 13:44:57]

nit: Can we call this "NewPathToken" instead? Because it really creates a new
node.

[Jarin, 2016/02/05 13:55:07]

Done.

+    return owner_->jsgraph()->Constant(token_id);
   }
   Node* NewPathTokenForImplicitFallThrough() {
-    return owner_->jsgraph()->Constant(-1);
+    return owner_->jsgraph()->Constant(

[Michael Starzinger, 2016/02/05 13:44:57]

nit: "return WrapToken(TokenDispenserForFinally::kFallThroughToken);"

[Jarin, 2016/02/05 13:55:08]

Done.

+        TokenDispenserForFinally::kFallThroughToken);
   }
   Node* NewPathDispatchCondition(Node* t1, Node* t2) {
     // TODO(mstarzinger): This should be machine()->WordEqual(), but our Phi
     // nodes all have kRepTagged|kTypeAny, which causes representation mismatch.
     return owner_->NewNode(owner_->javascript()->StrictEqual(), t1, t2);
   }
 
  private:
+  TokenDispenserForFinally dispenser_;
   AstGraphBuilder* owner_;
   ZoneVector<Entry> deferred_;
+  Node* return_token_;
+  Node* throw_token_;
 };
 
 
 // Control scope implementation for a BreakableStatement.
 class AstGraphBuilder::ControlScopeForBreakable : public ControlScope {
  public:
   ControlScopeForBreakable(AstGraphBuilder* owner, BreakableStatement* target,
                            ControlBuilder* control)
       : ControlScope(owner), target_(target), control_(control) {}
 
@@ skipping 1197 matching lines @@
   //  - ReturnStatement: It represents the return value being returned.
   //  - ThrowStatement: It represents the exception being thrown.
   //  - BreakStatement/ContinueStatement: Filled with the hole.
   //  - Falling through into finally-block: Filled with the hole.
   Node* result = try_control.GetResultValueNode();
   Node* token = try_control.GetDispatchTokenNode();
 
   // The result value, dispatch token and message is expected on the operand
   // stack (this is in sync with FullCodeGenerator::EnterFinallyBlock).
   Node* message = NewNode(javascript()->LoadMessage());
   environment()->Push(token);  // TODO(mstarzinger): Cook token!

[Michael Starzinger, 2016/02/05 13:44:58]

nit: Can we drop this TODO?

[Jarin, 2016/02/05 13:55:08]

Done.

   environment()->Push(result);
   environment()->Push(message);
 
   // Clear message object as we enter the finally block.
   Node* the_hole = jsgraph()->TheHoleConstant();
   NewNode(javascript()->StoreMessage(), the_hole);
 
   // Evaluate the finally-block.
   Visit(stmt->finally_block());
   try_control.EndFinally();
 
   // The result value, dispatch token and message is restored from the operand
   // stack (this is in sync with FullCodeGenerator::ExitFinallyBlock).
   message = environment()->Pop();
   result = environment()->Pop();
   token = environment()->Pop();  // TODO(mstarzinger): Uncook token!

[Michael Starzinger, 2016/02/05 13:44:57]

nit: Can we drop this TODO?

[Jarin, 2016/02/05 13:55:07]

Done.

   NewNode(javascript()->StoreMessage(), message);
 
   // Dynamic dispatch after the finally-block.
   commands->ApplyDeferredCommands(token, result);
 
   // TODO(mstarzinger): Remove bailout once everything works.
   if (!FLAG_turbo_try_finally) SetStackOverflow();
 }
 
 
@@ skipping 2825 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8