Fixed the range information for string lengths.

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 1562 matching lines @@
     case Runtime::kInlineMathFloor:
     case Runtime::kInlineMathSqrt:
     case Runtime::kInlineMathAcos:
     case Runtime::kInlineMathAsin:
     case Runtime::kInlineMathAtan:
     case Runtime::kInlineMathAtan2:
       return Bounds(Type::None(zone()), Type::Number());
     case Runtime::kInlineMathClz32:
       return Bounds(Type::None(), Type::Range(0, 32, zone()));
     case Runtime::kInlineStringGetLength:
-      // The string::length property is always an unsigned smi.
-      return Bounds(Type::None(), Type::Intersect(Type::UnsignedSmall(),
-                                                  Type::TaggedSigned()));
+      return Bounds(Type::None(), Type::Range(0, String::kMaxLength, zone()));
     default:
       break;
   }
   return Bounds::Unbounded(zone());
 }
 
 
 Bounds Typer::Visitor::TypeJSStackCheck(Node* node) {
   return Bounds::Unbounded(zone());
 }
@@ skipping 741 matching lines @@
       TYPED_ARRAYS(TYPED_ARRAY_CASE)
 #undef TYPED_ARRAY_CASE
     }
   }
   return Type::Constant(value, zone());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8