Revert r20974: Unify and simplify the FastCloneShallowArrayStub

src/code-stubs.h

 // Copyright 2012 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
@@ skipping 282 matching lines @@
 struct CodeStubInterfaceDescriptor {
   CodeStubInterfaceDescriptor();
   int register_param_count_;
 
   Register stack_parameter_count_;
   // if hint_stack_parameter_count_ > 0, the code stub can optimize the
   // return sequence. Default value is -1, which means it is ignored.
   int hint_stack_parameter_count_;
   StubFunctionMode function_mode_;
   Register* register_params_;
-  Representation* register_param_representations_;
 
   Address deoptimization_handler_;
   HandlerArgumentsMode handler_arguments_mode_;
 
   bool initialized() const { return register_param_count_ >= 0; }
 
   int environment_length() const {
     return register_param_count_;
   }
 
@@ skipping 284 matching lines @@
   static const int kFunction = 0;
 
  private:
   int slots_;
 };
 
 
 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;
 
   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_);
   }
 };
 
 
 class FastCloneShallowObjectStub : public HydrogenCodeStub {
  public:
   // Maximum number of properties in copied object.
   static const int kMaximumClonedProperties = 6;
 
   FastCloneShallowObjectStub(Isolate* isolate, int length)
@@ skipping 1845 matching lines @@
 
 
 class CallDescriptors {
  public:
   static void InitializeForIsolate(Isolate* isolate);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_CODE_STUBS_H_