diff --git a/src/frame-element.h b/src/frame-element.h
index a37a8dd350..3714ac9e66 100644
--- a/src/frame-element.h
+++ b/src/frame-element.h
@@ -28,7 +28,7 @@
 #ifndef V8_FRAME_ELEMENT_H_
 #define V8_FRAME_ELEMENT_H_
 
-#include "number-info.h"
+#include "number-info-inl.h"
 #include "macro-assembler.h"
 #include "zone.h"
 
@@ -58,13 +58,7 @@ class FrameElement BASE_EMBEDDED {
     // Copied elements do not have number info. Instead
     // we have to inspect their backing element in the frame.
     ASSERT(!is_copy());
-    if (!is_constant()) {
-      return NumberInfo::FromInt(NumberInfoField::decode(value_));
-    }
-    Handle<Object> value = handle();
-    if (value->IsSmi()) return NumberInfo::Smi();
-    if (value->IsHeapNumber()) return NumberInfo::HeapNumber();
-    return NumberInfo::Unknown();
+    return NumberInfo::FromInt(NumberInfoField::decode(value_));
   }
 
   inline void set_number_info(NumberInfo info) {
@@ -107,7 +101,8 @@ class FrameElement BASE_EMBEDDED {
   // compile time.
   static FrameElement ConstantElement(Handle<Object> value,
                                       SyncFlag is_synced) {
-    FrameElement result(value, is_synced);
+    NumberInfo info = NumberInfo::TypeFromValue(value);
+    FrameElement result(value, is_synced, info);
     return result;
   }
 
@@ -232,11 +227,11 @@ class FrameElement BASE_EMBEDDED {
   }
 
   // Used to construct constant elements.
-  FrameElement(Handle<Object> value, SyncFlag is_synced) {
+  FrameElement(Handle<Object> value, SyncFlag is_synced, NumberInfo info) {
     value_ = TypeField::encode(CONSTANT)
         | CopiedField::encode(false)
         | SyncedField::encode(is_synced != NOT_SYNCED)
-        | NumberInfoField::encode(NumberInfo::Uninitialized().ToInt())
+        | NumberInfoField::encode(info.ToInt())
         | DataField::encode(ConstantList()->length());
     ConstantList()->Add(value);
   }
diff --git a/src/ia32/codegen-ia32.cc b/src/ia32/codegen-ia32.cc
index d71b63988d..683b18a4ef 100644
--- a/src/ia32/codegen-ia32.cc
+++ b/src/ia32/codegen-ia32.cc
@@ -9728,7 +9728,7 @@ void FloatingPointHelper::LoadNumbersAsIntegers(MacroAssembler* masm,
   Label arg2_is_object, check_undefined_arg2;
   Label load_arg2, done;
 
-  if (!number_info.IsHeapNumber()) {
+  if (!number_info.IsDouble()) {
     if (!number_info.IsSmi()) {
       __ test(edx, Immediate(kSmiTagMask));
       __ j(not_zero, &arg1_is_object);
@@ -9747,7 +9747,7 @@ void FloatingPointHelper::LoadNumbersAsIntegers(MacroAssembler* masm,
 
   // Here edx has the untagged integer, eax has a Smi or a heap number.
   __ bind(&load_arg2);
-  if (!number_info.IsHeapNumber()) {
+  if (!number_info.IsDouble()) {
     // Test if arg2 is a Smi.
     if (!number_info.IsSmi()) {
       __ test(eax, Immediate(kSmiTagMask));
diff --git a/src/number-info-inl.h b/src/number-info-inl.h
new file mode 100644
index 0000000000..0b5a44d73f
--- /dev/null
+++ b/src/number-info-inl.h
@@ -0,0 +1,55 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_NUMBER_INFO_INL_H_
+#define V8_NUMBER_INFO_INL_H_
+
+#include "number-info.h"
+#include "objects-inl.h"
+
+namespace v8 {
+namespace internal {
+
+
+NumberInfo NumberInfo::TypeFromValue(Handle<Object> value) {
+  NumberInfo info;
+  if (value->IsSmi()) {
+    info = NumberInfo::Smi();
+  } else if (value->IsHeapNumber()) {
+    info = NumberInfo::IsInt32Double(HeapNumber::cast(*value)->value())
+        ? NumberInfo::Integer32()
+        : NumberInfo::Double();
+  } else {
+    info = NumberInfo::Unknown();
+  }
+  return info;
+}
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_NUMBER_INFO_INL_H_
diff --git a/src/number-info.h b/src/number-info.h
index 9537668a7d..6ecae532f6 100644
--- a/src/number-info.h
+++ b/src/number-info.h
@@ -37,7 +37,7 @@ namespace internal {
 //           |   \--------|
 //         Number      String
 //         /    |         |
-//  HeapNumber Integer32  |
+//    Double  Integer32   |
 //        |      |       /
 //        |     Smi     /
 //        |     /      /
@@ -57,7 +57,7 @@ class NumberInfo {
   // We know it's a Smi.
   static inline NumberInfo Smi();
   // We know it's a heap number.
-  static inline NumberInfo HeapNumber();
+  static inline NumberInfo Double();
   // We know it's a string.
   static inline NumberInfo String();
   // We haven't started collecting info yet.
@@ -85,7 +85,7 @@ class NumberInfo {
            t == kNumberType ||
            t == kInteger32Type ||
            t == kSmiType ||
-           t == kHeapNumberType);
+           t == kDoubleType);
     return NumberInfo(t);
   }
 
@@ -100,7 +100,7 @@ class NumberInfo {
            t == kNumberType ||
            t == kInteger32Type ||
            t == kSmiType ||
-           t == kHeapNumberType ||
+           t == kDoubleType ||
            t == kStringType);
     return NumberInfo(t);
   }
@@ -110,6 +110,22 @@ class NumberInfo {
     return NumberInfo(static_cast<Type>(a.type_ & b.type_));
   }
 
+
+  // Integer32 is an integer that can be represented as either a signed
+  // 32-bit integer or as an unsigned 32-bit integer. It has to be
+  // in the range [-2^31, 2^32 - 1].
+  static inline bool IsInt32Double(double value) {
+    if (value >= -0x80000000 && value <= 0xffffffffu) {
+      if (value <= 0x7fffffff && value == static_cast<int32_t>(value)) {
+        return true;
+      }
+      if (value == static_cast<uint32_t>(value)) return true;
+    }
+    return false;
+  }
+
+  static inline NumberInfo TypeFromValue(Handle<Object> value);
+
   inline bool IsUnknown() {
     return type_ == kUnknownType;
   }
@@ -129,9 +145,9 @@ class NumberInfo {
     return ((type_ & kInteger32Type) == kInteger32Type);
   }
 
-  inline bool IsHeapNumber() {
+  inline bool IsDouble() {
     ASSERT(type_ != kUninitializedType);
-    return ((type_ & kHeapNumberType) == kHeapNumberType);
+    return ((type_ & kDoubleType) == kDoubleType);
   }
 
   inline bool IsUninitialized() {
@@ -145,7 +161,7 @@ class NumberInfo {
       case kNumberType: return "NumberType";
       case kInteger32Type: return "Integer32Type";
       case kSmiType: return "SmiType";
-      case kHeapNumberType: return "HeapNumberType";
+      case kDoubleType: return "DoubleType";
       case kStringType: return "StringType";
       case kUninitializedType:
         UNREACHABLE();
@@ -163,7 +179,7 @@ class NumberInfo {
     kNumberType = 0x11,        // 010001
     kInteger32Type = 0x13,     // 010011
     kSmiType = 0x17,           // 010111
-    kHeapNumberType = 0x19,    // 011001
+    kDoubleType = 0x19,        // 011001
     kStringType = 0x30,        // 110000
     kUninitializedType = 0x3f  // 111111
   };
@@ -198,8 +214,8 @@ NumberInfo NumberInfo::Smi() {
 }
 
 
-NumberInfo NumberInfo::HeapNumber() {
-  return NumberInfo(kHeapNumberType);
+NumberInfo NumberInfo::Double() {
+  return NumberInfo(kDoubleType);
 }
 
 
diff --git a/src/register-allocator-inl.h b/src/register-allocator-inl.h
index 8453104ee2..396c73f9fe 100644
--- a/src/register-allocator-inl.h
+++ b/src/register-allocator-inl.h
@@ -106,13 +106,7 @@ void RegisterAllocator::Unuse(Register reg) {
 
 NumberInfo Result::number_info() const {
   ASSERT(is_valid());
-  if (!is_constant()) {
-    return NumberInfo::FromInt(NumberInfoField::decode(value_));
-  }
-  Handle<Object> value = handle();
-  if (value->IsSmi()) return NumberInfo::Smi();
-  if (value->IsHeapNumber()) return NumberInfo::HeapNumber();
-  return NumberInfo::Unknown();
+  return NumberInfo::FromInt(NumberInfoField::decode(value_));
 }
 
 
@@ -138,8 +132,8 @@ bool Result::is_integer32() const {
 }
 
 
-bool Result::is_heap_number() const {
-  return number_info().IsHeapNumber();
+bool Result::is_double() const {
+  return number_info().IsDouble();
 }
 
 } }  // namespace v8::internal
diff --git a/src/register-allocator.h b/src/register-allocator.h
index 2382f8a658..5798fa2d16 100644
--- a/src/register-allocator.h
+++ b/src/register-allocator.h
@@ -29,7 +29,7 @@
 #define V8_REGISTER_ALLOCATOR_H_
 
 #include "macro-assembler.h"
-#include "number-info.h"
+#include "number-info-inl.h"
 
 #if V8_TARGET_ARCH_IA32
 #include "ia32/register-allocator-ia32.h"
@@ -69,8 +69,9 @@ class Result BASE_EMBEDDED {
 
   // Construct a Result whose value is a compile-time constant.
   explicit Result(Handle<Object> value) {
+    NumberInfo info = NumberInfo::TypeFromValue(value);
     value_ = TypeField::encode(CONSTANT)
-        | NumberInfoField::encode(NumberInfo::Uninitialized().ToInt())
+        | NumberInfoField::encode(info.ToInt())
         | IsUntaggedInt32Field::encode(false)
         | DataField::encode(ConstantList()->length());
     ConstantList()->Add(value);
@@ -107,7 +108,7 @@ class Result BASE_EMBEDDED {
   inline bool is_number() const;
   inline bool is_smi() const;
   inline bool is_integer32() const;
-  inline bool is_heap_number() const;
+  inline bool is_double() const;
 
   bool is_valid() const { return type() != INVALID; }
   bool is_register() const { return type() == REGISTER; }
diff --git a/src/x64/virtual-frame-x64.cc b/src/x64/virtual-frame-x64.cc
index 79be20b1bd..ca1042334d 100644
--- a/src/x64/virtual-frame-x64.cc
+++ b/src/x64/virtual-frame-x64.cc
@@ -211,12 +211,7 @@ void VirtualFrame::EmitPush(Smi* smi_value) {
 
 void VirtualFrame::EmitPush(Handle<Object> value) {
   ASSERT(stack_pointer_ == element_count() - 1);
-  NumberInfo info = NumberInfo::Unknown();
-  if (value->IsSmi()) {
-    info = NumberInfo::Smi();
-  } else if (value->IsHeapNumber()) {
-    info = NumberInfo::HeapNumber();
-  }
+  NumberInfo info = NumberInfo::TypeFromValue(value);
   elements_.Add(FrameElement::MemoryElement(info));
   stack_pointer_++;
   __ Push(value);
diff --git a/tools/gyp/v8.gyp b/tools/gyp/v8.gyp
index d53143784e..9517533b9a 100644
--- a/tools/gyp/v8.gyp
+++ b/tools/gyp/v8.gyp
@@ -330,6 +330,7 @@
         '../../src/messages.cc',
         '../../src/messages.h',
         '../../src/natives.h',
+	'../../src/number-info-inl.h',
 	'../../src/number-info.h',
         '../../src/objects-debug.cc',
         '../../src/objects-inl.h',
diff --git a/tools/visual_studio/v8_base.vcproj b/tools/visual_studio/v8_base.vcproj
index 193e2a0968..6ab09ef5ab 100644
--- a/tools/visual_studio/v8_base.vcproj
+++ b/tools/visual_studio/v8_base.vcproj
@@ -688,6 +688,10 @@
 				RelativePath="..\..\src\natives.h"
 				>
 			</File>
+			<File
+				RelativePath="..\..\src\number-info-inl.h"
+				>
+			</File>
 			<File
 				RelativePath="..\..\src\number-info.h"
 				>
diff --git a/tools/visual_studio/v8_base_arm.vcproj b/tools/visual_studio/v8_base_arm.vcproj
index 9043d58acc..34dfbd0675 100644
--- a/tools/visual_studio/v8_base_arm.vcproj
+++ b/tools/visual_studio/v8_base_arm.vcproj
@@ -668,6 +668,10 @@
 				RelativePath="..\..\src\natives.h"
 				>
 			</File>
+			<File
+				RelativePath="..\..\src\number-info-inl.h"
+				>
+			</File>
 			<File
 				RelativePath="..\..\src\number-info.h"
 				>
diff --git a/tools/visual_studio/v8_base_x64.vcproj b/tools/visual_studio/v8_base_x64.vcproj
index 30437530a9..852fc8fc7b 100644
--- a/tools/visual_studio/v8_base_x64.vcproj
+++ b/tools/visual_studio/v8_base_x64.vcproj
@@ -665,6 +665,10 @@
 				RelativePath="..\..\src\natives.h"
 				>
 			</File>
+			<File
+				RelativePath="..\..\src\number-info-inl.h"
+				>
+			</File>
 			<File
 				RelativePath="..\..\src\number-info.h"
 				>