Revert r20974: Unify and simplify the FastCloneShallowArrayStub

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index 23acaef357cdc11fde021e1a0191d07c7142bd30..f33713737fca0815c36074e3f86d50d15190ab1c 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -300,7 +300,6 @@ struct CodeStubInterfaceDescriptor {
   int hint_stack_parameter_count_;
   StubFunctionMode function_mode_;
   Register* register_params_;
-  Representation* register_param_representations_;
 
   Address deoptimization_handler_;
   HandlerArgumentsMode handler_arguments_mode_;
@@ -605,18 +604,50 @@ class FastNewContextStub V8_FINAL : public HydrogenCodeStub {
 class FastCloneShallowArrayStub : public HydrogenCodeStub {
  public:
   // Maximum length of copied elements array.
-  static const int kMaximumInlinedCloneLength = 8;
+  static const int kMaximumClonedLength = 8;
+  enum Mode {
+    CLONE_ELEMENTS,
+    CLONE_DOUBLE_ELEMENTS,
+    COPY_ON_WRITE_ELEMENTS,
+    CLONE_ANY_ELEMENTS,
+    LAST_CLONE_MODE = CLONE_ANY_ELEMENTS
+  };
+
+  static const int kFastCloneModeCount = LAST_CLONE_MODE + 1;
 
   FastCloneShallowArrayStub(Isolate* isolate,
-                            AllocationSiteMode allocation_site_mode)
+                            Mode mode,
+                            AllocationSiteMode allocation_site_mode,
+                            int length)
       : HydrogenCodeStub(isolate),
-      allocation_site_mode_(allocation_site_mode) {}
+        mode_(mode),
+        allocation_site_mode_(allocation_site_mode),
+        length_((mode == COPY_ON_WRITE_ELEMENTS) ? 0 : length) {
+    ASSERT_GE(length_, 0);
+    ASSERT_LE(length_, kMaximumClonedLength);
+  }
 
+  Mode mode() const { return mode_; }
+  int length() const { return length_; }
   AllocationSiteMode allocation_site_mode() const {
     return allocation_site_mode_;
   }
 
-  virtual Handle<Code> GenerateCode();
+  ElementsKind ComputeElementsKind() const {
+    switch (mode()) {
+      case CLONE_ELEMENTS:
+      case COPY_ON_WRITE_ELEMENTS:
+        return FAST_ELEMENTS;
+      case CLONE_DOUBLE_ELEMENTS:
+        return FAST_DOUBLE_ELEMENTS;
+      case CLONE_ANY_ELEMENTS:
+        /*fall-through*/;
+    }
+    UNREACHABLE();
+    return LAST_ELEMENTS_KIND;
+  }
+
+  virtual Handle<Code> GenerateCode() V8_OVERRIDE;
 
   virtual void InitializeInterfaceDescriptor(
       CodeStubInterfaceDescriptor* descriptor) V8_OVERRIDE;
@@ -624,13 +655,22 @@ class FastCloneShallowArrayStub : public HydrogenCodeStub {
   static void InstallDescriptors(Isolate* isolate);
 
  private:
+  Mode mode_;
   AllocationSiteMode allocation_site_mode_;
+  int length_;
 
   class AllocationSiteModeBits: public BitField<AllocationSiteMode, 0, 1> {};
+  class ModeBits: public BitField<Mode, 1, 4> {};
+  class LengthBits: public BitField<int, 5, 4> {};
   // Ensure data fits within available bits.
+  STATIC_ASSERT(LAST_ALLOCATION_SITE_MODE == 1);
+  STATIC_ASSERT(kFastCloneModeCount < 16);
+  STATIC_ASSERT(kMaximumClonedLength < 16);
   Major MajorKey() { return FastCloneShallowArray; }
   int NotMissMinorKey() {
-    return AllocationSiteModeBits::encode(allocation_site_mode_);
+    return AllocationSiteModeBits::encode(allocation_site_mode_)
+        | ModeBits::encode(mode_)
+        | LengthBits::encode(length_);
   }
 };