Add monomorphic CompareNilICs and Crankshaft support

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index 55d7e5d809d12227531bded89766b17576d1e3e4..fa609240e0850ad1b427e992c101330e90c00585 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -47,6 +47,7 @@ namespace internal {
   V(StringCompare)                       \
   V(Compare)                             \
   V(CompareIC)                           \
+  V(CompareNilIC)                        \
   V(MathPow)                             \
   V(StringLength)                        \
   V(FunctionPrototype)                   \
@@ -946,6 +947,102 @@ class ICCompareStub: public PlatformCodeStub {
 };
 
 
+class CompareNilICStub : public HydrogenCodeStub  {
+ public:
+  enum Types {
+    kCompareAgainstNull = 1 << 0,
+    kCompareAgainstUndefined = 1 << 1,
+    kCompareAgainstMonomorphicMap = 1 << 2,
+    kCompareAgainstUndetectable = 1 << 3,
+    kFullCompare = kCompareAgainstNull | kCompareAgainstUndefined |
+        kCompareAgainstUndetectable
+  };
+
+  CompareNilICStub(EqualityKind kind, NilValue nil, Types types)
+      : HydrogenCodeStub(CODE_STUB_IS_NOT_MISS), bit_field_(0) {
+    bit_field_ = EqualityKindField::encode(kind) |
+        NilValueField::encode(nil) |
+        TypesField::encode(types);
+  }
+
+  virtual InlineCacheState GetICState() {
+    Types types = GetTypes();
+    if (types == kFullCompare) {
+      return MEGAMORPHIC;
+    } else if ((types & kCompareAgainstMonomorphicMap) != 0) {
+      return MONOMORPHIC;
+    } else {
+      return PREMONOMORPHIC;
+    }
+  }
+
+  virtual Code::Kind GetCodeKind() const { return Code::COMPARE_NIL_IC; }
+
+  Handle<Code> GenerateCode();
+
+  static Handle<Code> GetUninitialized(Isolate* isolate,
+                                       EqualityKind kind,
+                                       NilValue nil) {
+    return CompareNilICStub(kind, nil).GetCode(isolate);
+  }
+
+  virtual void InitializeInterfaceDescriptor(
+      Isolate* isolate,
+      CodeStubInterfaceDescriptor* descriptor);
+
+  static void InitializeForIsolate(Isolate* isolate) {
+    CompareNilICStub compare_stub(kStrictEquality, kNullValue);
+    compare_stub.InitializeInterfaceDescriptor(
+        isolate,
+        isolate->code_stub_interface_descriptor(CodeStub::CompareNilIC));
+  }
+
+  virtual Code::ExtraICState GetExtraICState() {
+    return bit_field_;
+  }
+
+  EqualityKind GetKind() { return EqualityKindField::decode(bit_field_); }
+  NilValue GetNilValue() { return NilValueField::decode(bit_field_); }
+  Types GetTypes() { return TypesField::decode(bit_field_); }
+
+  static Types TypesFromExtraICState(
+      Code::ExtraICState state) {
+    return TypesField::decode(state);
+  }
+  static EqualityKind EqualityKindFromExtraICState(
+      Code::ExtraICState state) {
+    return EqualityKindField::decode(state);
+  }
+  static NilValue NilValueFromExtraICState(Code::ExtraICState state) {
+    return NilValueField::decode(state);
+  }
+
+  static Types GetPatchedICFlags(Code::ExtraICState extra_ic_state,
+                                 Handle<Object> object,
+                                 bool* already_monomorphic);
+
+ private:
+  friend class CompareNilIC;
+
+  class EqualityKindField : public BitField<EqualityKind, 0, 1> {};
+  class NilValueField : public BitField<NilValue, 1, 1> {};
+  class TypesField : public BitField<Types, 3, 4> {};
+
+  CompareNilICStub(EqualityKind kind, NilValue nil)
+      : HydrogenCodeStub(CODE_STUB_IS_MISS), bit_field_(0) {
+    bit_field_ = EqualityKindField::encode(kind) |
+        NilValueField::encode(nil);
+  }
+
+  virtual CodeStub::Major MajorKey() { return CompareNilIC; }
+  virtual int NotMissMinorKey() { return bit_field_; }
+
+  int bit_field_;
+
+  DISALLOW_COPY_AND_ASSIGN(CompareNilICStub);
+};
+
+
 class CEntryStub : public PlatformCodeStub {
  public:
   explicit CEntryStub(int result_size,