Better typing and type verification

src/compiler/typer.cc

Index: src/compiler/typer.cc
diff --git a/src/compiler/typer.cc b/src/compiler/typer.cc
index f50adbd5ed10f742dd96a1f064a949d951fa9072..061b186f236200508dc32c41840d3914e0772639 100644
--- a/src/compiler/typer.cc
+++ b/src/compiler/typer.cc
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "src/bootstrapper.h"
 #include "src/compiler/graph-inl.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/node.h"
@@ -14,7 +15,19 @@ namespace v8 {
 namespace internal {
 namespace compiler {
 
-Typer::Typer(Zone* zone) : zone_(zone) {
+class Typer::Decorator : public GraphDecorator {
+ public:
+  explicit Decorator(Typer* typer) : typer_(typer) {}
+  virtual void Decorate(Node* node);
+
+ private:
+  Typer* typer_;
+};
+
+
+Typer::Typer(Graph* graph, MaybeHandle<Context> context)
+    : graph_(graph), context_(context), decorator_(NULL) {
+  Zone* zone = this->zone();
   Factory* f = zone->isolate()->factory();
 
   Type* number = Type::Number();
@@ -69,13 +82,20 @@ Typer::Typer(Zone* zone) : zone_(zone) {
   uint32_array_fun_ = Type::Function(uint32_array, arg1, arg2, arg3, zone);
   float32_array_fun_ = Type::Function(float32_array, arg1, arg2, arg3, zone);
   float64_array_fun_ = Type::Function(float64_array, arg1, arg2, arg3, zone);
+
+  decorator_ = new (zone) Decorator(this);
+  graph_->AddDecorator(decorator_);
+}
+
+
+Typer::~Typer() {
+  graph_->RemoveDecorator(decorator_);
 }
 
 
 class Typer::Visitor : public NullNodeVisitor {
  public:
-  Visitor(Typer* typer, MaybeHandle<Context> context)
-      : typer_(typer), context_(context) {}
+  explicit Visitor(Typer* typer) : typer_(typer) {}
 
   Bounds TypeNode(Node* node) {
     switch (node->opcode()) {
@@ -102,49 +122,47 @@ class Typer::Visitor : public NullNodeVisitor {
   VALUE_OP_LIST(DECLARE_METHOD)
 #undef DECLARE_METHOD
 
-  Bounds OperandType(Node* node, int i) {
-    return NodeProperties::GetBounds(NodeProperties::GetValueInput(node, i));
+  Bounds BoundsOrNone(Node* node) {
+    return NodeProperties::IsTyped(node)
+        ? NodeProperties::GetBounds(node) : Bounds(Type::None(zone()));
   }
 
-  Type* ContextType(Node* node) {
-    Bounds result =
-        NodeProperties::GetBounds(NodeProperties::GetContextInput(node));
+  Bounds Operand(Node* node, int i) {
+    Node* operand_node = NodeProperties::GetValueInput(node, i);
+    return BoundsOrNone(operand_node);
+  }
+
+  Bounds ContextOperand(Node* node) {
+    Bounds result = BoundsOrNone(NodeProperties::GetContextInput(node));
     DCHECK(result.upper->Maybe(Type::Internal()));
     // TODO(rossberg): More precisely, instead of the above assertion, we should
     // back-propagate the constraint that it has to be a subtype of Internal.
-    return result.upper;
+    return result;
   }
 
   Zone* zone() { return typer_->zone(); }
   Isolate* isolate() { return typer_->isolate(); }
-  MaybeHandle<Context> context() { return context_; }
+  Graph* graph() { return typer_->graph(); }
+  MaybeHandle<Context> context() { return typer_->context(); }
 
  private:
   Typer* typer_;
-  MaybeHandle<Context> context_;
 };
 
 
 class Typer::RunVisitor : public Typer::Visitor {
  public:
-  RunVisitor(Typer* typer, MaybeHandle<Context> context)
-      : Visitor(typer, context),
+  explicit RunVisitor(Typer* typer)
+      : Visitor(typer),
         redo(NodeSet::key_compare(), NodeSet::allocator_type(typer->zone())) {}
 
   GenericGraphVisit::Control Post(Node* node) {
-    if (OperatorProperties::HasValueOutput(node->op())) {
+    if (OperatorProperties::HasValueOutput(node->op()) &&
+        !NodeProperties::IsTyped(node)) {
       Bounds bounds = TypeNode(node);
       NodeProperties::SetBounds(node, bounds);
       // Remember incompletely typed nodes for least fixpoint iteration.
-      int arity = OperatorProperties::GetValueInputCount(node->op());
-      for (int i = 0; i < arity; ++i) {
-        // TODO(rossberg): change once IsTyped is available.
-        // if (!NodeProperties::IsTyped(NodeProperties::GetValueInput(node, i)))
-        if (OperandType(node, i).upper->Is(Type::None())) {
-          redo.insert(node);
-          break;
-        }
-      }
+      if (!NodeProperties::AllValueInputsAreTyped(node)) redo.insert(node);
     }
     return GenericGraphVisit::CONTINUE;
   }
@@ -155,8 +173,7 @@ class Typer::RunVisitor : public Typer::Visitor {
 
 class Typer::NarrowVisitor : public Typer::Visitor {
  public:
-  NarrowVisitor(Typer* typer, MaybeHandle<Context> context)
-      : Visitor(typer, context) {}
+  explicit NarrowVisitor(Typer* typer) : Visitor(typer) {}
 
   GenericGraphVisit::Control Pre(Node* node) {
     if (OperatorProperties::HasValueOutput(node->op())) {
@@ -180,16 +197,15 @@ class Typer::NarrowVisitor : public Typer::Visitor {
 
 class Typer::WidenVisitor : public Typer::Visitor {
  public:
-  WidenVisitor(Typer* typer, MaybeHandle<Context> context)
-      : Visitor(typer, context) {}
+  explicit WidenVisitor(Typer* typer) : Visitor(typer) {}
 
   GenericGraphVisit::Control Pre(Node* node) {
     if (OperatorProperties::HasValueOutput(node->op())) {
-      Bounds previous = NodeProperties::GetBounds(node);
+      Bounds previous = BoundsOrNone(node);
       Bounds bounds = TypeNode(node);
       DCHECK(previous.lower->Is(bounds.lower));
       DCHECK(previous.upper->Is(bounds.upper));
-      NodeProperties::SetBounds(node, bounds);  // TODO(rossberg): Either?
+      NodeProperties::SetBounds(node, bounds);
       // Stop when nothing changed (but allow re-entry in case it does later).
       return bounds.Narrows(previous)
           ? GenericGraphVisit::DEFER : GenericGraphVisit::REENTER;
@@ -204,33 +220,37 @@ class Typer::WidenVisitor : public Typer::Visitor {
 };
 
 
-void Typer::Run(Graph* graph, MaybeHandle<Context> context) {
-  RunVisitor typing(this, context);
-  graph->VisitNodeInputsFromEnd(&typing);
+void Typer::Run() {
+  RunVisitor typing(this);
+  graph_->VisitNodeInputsFromEnd(&typing);
   // Find least fixpoint.
-  for (NodeSetIter i = typing.redo.begin(); i != typing.redo.end(); ++i) {
-    Widen(graph, *i, context);
+  WidenVisitor widen(this);
+  for (NodeSetIter it = typing.redo.begin(); it != typing.redo.end(); ++it) {
+    graph_->VisitNodeUsesFrom(*it, &widen);
   }
 }
 
 
-void Typer::Narrow(Graph* graph, Node* start, MaybeHandle<Context> context) {
-  NarrowVisitor typing(this, context);
-  graph->VisitNodeUsesFrom(start, &typing);
+void Typer::Narrow(Node* start) {
+  NarrowVisitor typing(this);
+  graph_->VisitNodeUsesFrom(start, &typing);
 }
 
 
-void Typer::Widen(Graph* graph, Node* start, MaybeHandle<Context> context) {
-  WidenVisitor typing(this, context);
-  graph->VisitNodeUsesFrom(start, &typing);
-}
-
-
-void Typer::Init(Node* node) {
+void Typer::Decorator::Decorate(Node* node) {
   if (OperatorProperties::HasValueOutput(node->op())) {
-    Visitor typing(this, MaybeHandle<Context>());
-    Bounds bounds = typing.TypeNode(node);
-    NodeProperties::SetBounds(node, bounds);
+    // Only eagerly type-decorate nodes with known input types.
+    // Other cases will generally require a proper fixpoint iteration with Run.
+    bool is_typed = NodeProperties::IsTyped(node);
+    if (is_typed || NodeProperties::AllValueInputsAreTyped(node)) {
+      Visitor typing(typer_);
+      Bounds bounds = typing.TypeNode(node);
+      if (is_typed) {
+        bounds =
+          Bounds::Both(bounds, NodeProperties::GetBounds(node), typer_->zone());
+      }
+      NodeProperties::SetBounds(node, bounds);
+    }
   }
 }
 
@@ -241,7 +261,7 @@ void Typer::Init(Node* node) {
 // Control operators.
 
 Bounds Typer::Visitor::TypeStart(Node* node) {
-  return Bounds(Type::Internal(zone()));
+  return Bounds(Type::None(zone()), Type::Internal(zone()));
 }
 
 
@@ -289,15 +309,15 @@ Bounds Typer::Visitor::TypeHeapConstant(Node* node) {
 
 
 Bounds Typer::Visitor::TypeExternalConstant(Node* node) {
-  return Bounds(Type::Internal(zone()));
+  return Bounds(Type::None(zone()), Type::Internal(zone()));
 }
 
 
 Bounds Typer::Visitor::TypePhi(Node* node) {
   int arity = OperatorProperties::GetValueInputCount(node->op());
-  Bounds bounds = OperandType(node, 0);
+  Bounds bounds = Operand(node, 0);
   for (int i = 1; i < arity; ++i) {
-    bounds = Bounds::Either(bounds, OperandType(node, i), zone());
+    bounds = Bounds::Either(bounds, Operand(node, i), zone());
   }
   return bounds;
 }
@@ -316,18 +336,18 @@ Bounds Typer::Visitor::TypeValueEffect(Node* node) {
 
 
 Bounds Typer::Visitor::TypeFinish(Node* node) {
-  return OperandType(node, 0);
+  return Operand(node, 0);
 }
 
 
 Bounds Typer::Visitor::TypeFrameState(Node* node) {
   // TODO(rossberg): Ideally FrameState wouldn't have a value output.
-  return Bounds(Type::Internal(zone()));
+  return Bounds(Type::None(zone()), Type::Internal(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeStateValues(Node* node) {
-  return Bounds(Type::Internal(zone()));
+  return Bounds(Type::None(zone()), Type::Internal(zone()));
 }
 
 
@@ -344,9 +364,9 @@ Bounds Typer::Visitor::TypeProjection(Node* node) {
 
 // JS comparison operators.
 
-#define DEFINE_METHOD(x)                       \
+#define DEFINE_METHOD(x) \
   Bounds Typer::Visitor::Type##x(Node* node) { \
-    return Bounds(Type::Boolean(zone()));      \
+    return Bounds(Type::None(zone()), Type::Boolean(zone())); \
   }
 JS_COMPARE_BINOP_LIST(DEFINE_METHOD)
 #undef DEFINE_METHOD
@@ -355,8 +375,8 @@ JS_COMPARE_BINOP_LIST(DEFINE_METHOD)
 // JS bitwise operators.
 
 Bounds Typer::Visitor::TypeJSBitwiseOr(Node* node) {
-  Bounds left = OperandType(node, 0);
-  Bounds right = OperandType(node, 1);
+  Bounds left = Operand(node, 0);
+  Bounds right = Operand(node, 1);
   Type* upper = Type::Union(left.upper, right.upper, zone());
   if (!upper->Is(Type::Signed32())) upper = Type::Signed32(zone());
   Type* lower = Type::Intersect(Type::SignedSmall(zone()), upper, zone());
@@ -365,8 +385,8 @@ Bounds Typer::Visitor::TypeJSBitwiseOr(Node* node) {
 
 
 Bounds Typer::Visitor::TypeJSBitwiseAnd(Node* node) {
-  Bounds left = OperandType(node, 0);
-  Bounds right = OperandType(node, 1);
+  Bounds left = Operand(node, 0);
+  Bounds right = Operand(node, 1);
   Type* upper = Type::Union(left.upper, right.upper, zone());
   if (!upper->Is(Type::Signed32())) upper = Type::Signed32(zone());
   Type* lower = Type::Intersect(Type::SignedSmall(zone()), upper, zone());
@@ -375,30 +395,30 @@ Bounds Typer::Visitor::TypeJSBitwiseAnd(Node* node) {
 
 
 Bounds Typer::Visitor::TypeJSBitwiseXor(Node* node) {
-  return Bounds(Type::SignedSmall(zone()), Type::Signed32(zone()));
+  return Bounds(Type::None(zone()), Type::Signed32(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSShiftLeft(Node* node) {
-  return Bounds(Type::SignedSmall(zone()), Type::Signed32(zone()));
+  return Bounds(Type::None(zone()), Type::Signed32(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSShiftRight(Node* node) {
-  return Bounds(Type::SignedSmall(zone()), Type::Signed32(zone()));
+  return Bounds(Type::None(zone()), Type::Signed32(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSShiftRightLogical(Node* node) {
-  return Bounds(Type::UnsignedSmall(zone()), Type::Unsigned32(zone()));
+  return Bounds(Type::None(zone()), Type::Unsigned32(zone()));
 }
 
 
 // JS arithmetic operators.
 
 Bounds Typer::Visitor::TypeJSAdd(Node* node) {
-  Bounds left = OperandType(node, 0);
-  Bounds right = OperandType(node, 1);
+  Bounds left = Operand(node, 0);
+  Bounds right = Operand(node, 1);
   Type* lower =
       left.lower->Is(Type::None()) || right.lower->Is(Type::None()) ?
           Type::None(zone()) :
@@ -418,46 +438,46 @@ Bounds Typer::Visitor::TypeJSAdd(Node* node) {
 
 
 Bounds Typer::Visitor::TypeJSSubtract(Node* node) {
-  return Bounds(Type::SignedSmall(zone()), Type::Number(zone()));
+  return Bounds(Type::None(zone()), Type::Number(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSMultiply(Node* node) {
-  return Bounds(Type::SignedSmall(zone()), Type::Number(zone()));
+  return Bounds(Type::None(zone()), Type::Number(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSDivide(Node* node) {
-  return Bounds(Type::SignedSmall(zone()), Type::Number(zone()));
+  return Bounds(Type::None(zone()), Type::Number(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSModulus(Node* node) {
-  return Bounds(Type::SignedSmall(zone()), Type::Number(zone()));
+  return Bounds(Type::None(zone()), Type::Number(zone()));
 }
 
 
 // JS unary operators.
 
 Bounds Typer::Visitor::TypeJSUnaryNot(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSTypeOf(Node* node) {
-  return Bounds(Type::InternalizedString(zone()));
+  return Bounds(Type::None(zone()), Type::InternalizedString(zone()));
 }
 
 
 // JS conversion operators.
 
 Bounds Typer::Visitor::TypeJSToBoolean(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSToNumber(Node* node) {
-  return Bounds(Type::SignedSmall(zone()), Type::Number(zone()));
+  return Bounds(Type::None(zone()), Type::Number(zone()));
 }
 
 
@@ -484,8 +504,8 @@ Bounds Typer::Visitor::TypeJSCreate(Node* node) {
 
 
 Bounds Typer::Visitor::TypeJSLoadProperty(Node* node) {
-  Bounds object = OperandType(node, 0);
-  Bounds name = OperandType(node, 1);
+  Bounds object = Operand(node, 0);
+  Bounds name = Operand(node, 1);
   Bounds result = Bounds::Unbounded(zone());
   // TODO(rossberg): Use range types and sized array types to filter undefined.
   if (object.lower->IsArray() && name.lower->Is(Type::Integral32())) {
@@ -518,24 +538,24 @@ Bounds Typer::Visitor::TypeJSStoreNamed(Node* node) {
 
 
 Bounds Typer::Visitor::TypeJSDeleteProperty(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSHasProperty(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSInstanceOf(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 // JS context operators.
 
 Bounds Typer::Visitor::TypeJSLoadContext(Node* node) {
-  Bounds outer = OperandType(node, 0);
+  Bounds outer = Operand(node, 0);
   DCHECK(outer.upper->Maybe(Type::Internal()));
   // TODO(rossberg): More precisely, instead of the above assertion, we should
   // back-propagate the constraint that it has to be a subtype of Internal.
@@ -580,39 +600,39 @@ Bounds Typer::Visitor::TypeJSStoreContext(Node* node) {
 
 
 Bounds Typer::Visitor::TypeJSCreateFunctionContext(Node* node) {
-  Type* outer = ContextType(node);
-  return Bounds(Type::Context(outer, zone()));
+  Bounds outer = ContextOperand(node);
+  return Bounds(Type::Context(outer.upper, zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSCreateCatchContext(Node* node) {
-  Type* outer = ContextType(node);
-  return Bounds(Type::Context(outer, zone()));
+  Bounds outer = ContextOperand(node);
+  return Bounds(Type::Context(outer.upper, zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSCreateWithContext(Node* node) {
-  Type* outer = ContextType(node);
-  return Bounds(Type::Context(outer, zone()));
+  Bounds outer = ContextOperand(node);
+  return Bounds(Type::Context(outer.upper, zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSCreateBlockContext(Node* node) {
-  Type* outer = ContextType(node);
-  return Bounds(Type::Context(outer, zone()));
+  Bounds outer = ContextOperand(node);
+  return Bounds(Type::Context(outer.upper, zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSCreateModuleContext(Node* node) {
   // TODO(rossberg): this is probably incorrect
-  Type* outer = ContextType(node);
-  return Bounds(Type::Context(outer, zone()));
+  Bounds outer = ContextOperand(node);
+  return Bounds(Type::Context(outer.upper, zone()));
 }
 
 
 Bounds Typer::Visitor::TypeJSCreateGlobalContext(Node* node) {
-  Type* outer = ContextType(node);
-  return Bounds(Type::Context(outer, zone()));
+  Bounds outer = ContextOperand(node);
+  return Bounds(Type::Context(outer.upper, zone()));
 }
 
 
@@ -629,7 +649,7 @@ Bounds Typer::Visitor::TypeJSCallConstruct(Node* node) {
 
 
 Bounds Typer::Visitor::TypeJSCallFunction(Node* node) {
-  Bounds fun = OperandType(node, 0);
+  Bounds fun = Operand(node, 0);
   Type* lower = fun.lower->IsFunction()
       ? fun.lower->AsFunction()->Result() : Type::None(zone());
   Type* upper = fun.upper->IsFunction()
@@ -651,57 +671,57 @@ Bounds Typer::Visitor::TypeJSDebugger(Node* node) {
 // Simplified operators.
 
 Bounds Typer::Visitor::TypeBooleanNot(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeBooleanToNumber(Node* node) {
-  return Bounds(Type::Number(zone()));
+  return Bounds(Type::None(zone()), Type::Number(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeNumberEqual(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeNumberLessThan(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeNumberLessThanOrEqual(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeNumberAdd(Node* node) {
-  return Bounds(Type::Number(zone()));
+  return Bounds(Type::None(zone()), Type::Number(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeNumberSubtract(Node* node) {
-  return Bounds(Type::Number(zone()));
+  return Bounds(Type::None(zone()), Type::Number(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeNumberMultiply(Node* node) {
-  return Bounds(Type::Number(zone()));
+  return Bounds(Type::None(zone()), Type::Number(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeNumberDivide(Node* node) {
-  return Bounds(Type::Number(zone()));
+  return Bounds(Type::None(zone()), Type::Number(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeNumberModulus(Node* node) {
-  return Bounds(Type::Number(zone()));
+  return Bounds(Type::None(zone()), Type::Number(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeNumberToInt32(Node* node) {
-  Bounds arg = OperandType(node, 0);
+  Bounds arg = Operand(node, 0);
   Type* s32 = Type::Signed32(zone());
   Type* lower = arg.lower->Is(s32) ? arg.lower : s32;
   Type* upper = arg.upper->Is(s32) ? arg.upper : s32;
@@ -710,7 +730,7 @@ Bounds Typer::Visitor::TypeNumberToInt32(Node* node) {
 
 
 Bounds Typer::Visitor::TypeNumberToUint32(Node* node) {
-  Bounds arg = OperandType(node, 0);
+  Bounds arg = Operand(node, 0);
   Type* u32 = Type::Unsigned32(zone());
   Type* lower = arg.lower->Is(u32) ? arg.lower : u32;
   Type* upper = arg.upper->Is(u32) ? arg.upper : u32;
@@ -719,74 +739,75 @@ Bounds Typer::Visitor::TypeNumberToUint32(Node* node) {
 
 
 Bounds Typer::Visitor::TypeReferenceEqual(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeStringEqual(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeStringLessThan(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeStringLessThanOrEqual(Node* node) {
-  return Bounds(Type::Boolean(zone()));
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeStringAdd(Node* node) {
-  return Bounds(Type::String(zone()));
+  return Bounds(Type::None(zone()), Type::String(zone()));
 }
 
 
 Bounds Typer::Visitor::TypeChangeTaggedToInt32(Node* node) {
   // TODO(titzer): type is type of input, representation is Word32.
-  return Bounds(Type::Integral32());
+  return Bounds(Type::None(zone()), Type::Integral32());
 }
 
 
 Bounds Typer::Visitor::TypeChangeTaggedToUint32(Node* node) {
-  return Bounds(Type::Integral32());  // TODO(titzer): add appropriate rep
+  // TODO(titzer): add appropriate rep
+  return Bounds(Type::None(zone()), Type::Integral32());
 }
 
 
 Bounds Typer::Visitor::TypeChangeTaggedToFloat64(Node* node) {
   // TODO(titzer): type is type of input, representation is Float64.
-  return Bounds(Type::Number());
+  return Bounds(Type::None(zone()), Type::Number());
 }
 
 
 Bounds Typer::Visitor::TypeChangeInt32ToTagged(Node* node) {
   // TODO(titzer): type is type of input, representation is Tagged.
-  return Bounds(Type::Integral32());
+  return Bounds(Type::None(zone()), Type::Integral32());
 }
 
 
 Bounds Typer::Visitor::TypeChangeUint32ToTagged(Node* node) {
   // TODO(titzer): type is type of input, representation is Tagged.
-  return Bounds(Type::Unsigned32());
+  return Bounds(Type::None(zone()), Type::Unsigned32());
 }
 
 
 Bounds Typer::Visitor::TypeChangeFloat64ToTagged(Node* node) {
   // TODO(titzer): type is type of input, representation is Tagged.
-  return Bounds(Type::Number());
+  return Bounds(Type::None(zone()), Type::Number());
 }
 
 
 Bounds Typer::Visitor::TypeChangeBoolToBit(Node* node) {
   // TODO(titzer): type is type of input, representation is Bit.
-  return Bounds(Type::Boolean());
+  return Bounds(Type::None(zone()), Type::Boolean());
 }
 
 
 Bounds Typer::Visitor::TypeChangeBitToBool(Node* node) {
   // TODO(titzer): type is type of input, representation is Tagged.
-  return Bounds(Type::Boolean());
+  return Bounds(Type::None(zone()), Type::Boolean());
 }
 
 
@@ -814,7 +835,6 @@ Bounds Typer::Visitor::TypeStoreElement(Node* node) {
 
 // Machine operators.
 
-
 Bounds Typer::Visitor::TypeLoad(Node* node) {
   return Bounds::Unbounded(zone());
 }
@@ -1206,25 +1226,6 @@ Type* Typer::Visitor::TypeConstant(Handle<Object> value) {
   return Type::Constant(value, zone());
 }
 
-
-namespace {
-
-class TyperDecorator : public GraphDecorator {
- public:
-  explicit TyperDecorator(Typer* typer) : typer_(typer) {}
-  virtual void Decorate(Node* node) { typer_->Init(node); }
-
- private:
-  Typer* typer_;
-};
-
-}
-
-
-void Typer::DecorateGraph(Graph* graph) {
-  graph->AddDecorator(new (zone()) TyperDecorator(this));
-}
-
 }
 }
 }  // namespace v8::internal::compiler