[turbofan] First step towards sanitizing for-in and making it optimizable.

src/compiler/typer.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/base/flags.h"
 #include "src/bootstrapper.h"
 #include "src/compiler/graph-reducer.h"
 #include "src/compiler/js-operator.h"
 #include "src/compiler/node.h"
 #include "src/compiler/node-properties.h"
@@ skipping 1584 matching lines @@
       return Bounds(Type::None(), Type::Range(0, 32, zone()));
     case Runtime::kInlineStringGetLength:
       return Bounds(Type::None(), Type::Range(0, String::kMaxLength, zone()));
     default:
       break;
   }
   return Bounds::Unbounded(zone());
 }
 
 
+Bounds Typer::Visitor::TypeJSForInNext(Node* node) {
+  return Bounds(Type::None(zone()),
+                Type::Union(Type::Name(), Type::Undefined(), zone()));
+}
+
+
+Bounds Typer::Visitor::TypeJSForInPrepare(Node* node) {
+  // TODO(bmeurer): Return a tuple type here.
+  return Bounds::Unbounded(zone());
+}
+
+
+Bounds Typer::Visitor::TypeJSForInDone(Node* node) {
+  return Bounds(Type::None(zone()), Type::Boolean(zone()));
+}
+
+
+Bounds Typer::Visitor::TypeJSForInStep(Node* node) {
+  STATIC_ASSERT(Map::EnumLengthBits::kMax <= FixedArray::kMaxLength);
+  return Bounds(Type::None(zone()),
+                Type::Range(1, FixedArray::kMaxLength + 1, zone()));
+}
+
+
 Bounds Typer::Visitor::TypeJSStackCheck(Node* node) {
   return Bounds::Unbounded(zone());
 }
 
 
 // Simplified operators.
 
 
 Bounds Typer::Visitor::TypeBooleanNot(Node* node) {
   return Bounds(Type::None(zone()), Type::Boolean(zone()));
@@ skipping 751 matching lines @@
       TYPED_ARRAYS(TYPED_ARRAY_CASE)
 #undef TYPED_ARRAY_CASE
     }
   }
   return Type::Constant(value, zone());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8