Multiple stubs can point to the same calling convention.

src/code-stubs.h

 // Copyright 2012 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.
 
 #ifndef V8_CODE_STUBS_H_
 #define V8_CODE_STUBS_H_
 
 #include "src/allocation.h"
 #include "src/assembler.h"
 #include "src/codegen.h"
@@ skipping 263 matching lines @@
  protected:
   // Generates the assembler code for the stub.
   virtual void Generate(MacroAssembler* masm) = 0;
 };
 
 
 enum StubFunctionMode { NOT_JS_FUNCTION_STUB_MODE, JS_FUNCTION_STUB_MODE };
 enum HandlerArgumentsMode { DONT_PASS_ARGUMENTS, PASS_ARGUMENTS };
 
 
-class CodeStubInterfaceDescriptor: public InterfaceDescriptor {
+class CodeStubInterfaceDescriptor {
  public:
   CodeStubInterfaceDescriptor();
 
-  void Initialize(CodeStub::Major major, int register_parameter_count,
-                  Register* registers, Address deoptimization_handler = NULL,
-                  Representation* register_param_representations = NULL,
+  void Initialize(CodeStub::Major major,
+                  CallInterfaceDescriptor* call_descriptor,
+                  Address deoptimization_handler = NULL,
                   int hint_stack_parameter_count = -1,
                   StubFunctionMode function_mode = NOT_JS_FUNCTION_STUB_MODE);
-  void Initialize(CodeStub::Major major, int register_parameter_count,
-                  Register* registers, Register stack_parameter_count,
+  void Initialize(CodeStub::Major major,
+                  CallInterfaceDescriptor* call_descriptor,
+                  Register stack_parameter_count,
                   Address deoptimization_handler = NULL,
-                  Representation* register_param_representations = NULL,
                   int hint_stack_parameter_count = -1,
                   StubFunctionMode function_mode = NOT_JS_FUNCTION_STUB_MODE,
                   HandlerArgumentsMode handler_mode = DONT_PASS_ARGUMENTS);
 
   void SetMissHandler(ExternalReference handler) {
     miss_handler_ = handler;
     has_miss_handler_ = true;
     // Our miss handler infrastructure doesn't currently support
     // variable stack parameter counts.
     DCHECK(!stack_parameter_count_.is_valid());
   }
 
+  bool IsInitialized() const { return call_descriptor_ != NULL; }
+
+  CallInterfaceDescriptor* call_descriptor() const { return call_descriptor_; }
+
+  int GetEnvironmentLength() const {
+    return call_descriptor()->GetEnvironmentLength();
+  }
+
+  int GetRegisterParameterCount() const {
+    return call_descriptor()->GetRegisterParameterCount();
+  }
+
+  Register GetParameterRegister(int index) const {
+    return call_descriptor()->GetParameterRegister(index);
+  }
+
+  Representation GetParameterRepresentation(int index) const {
+    return call_descriptor()->GetParameterRepresentation(index);
+  }
+
+  int GetEnvironmentParameterCount() const {
+    return call_descriptor()->GetEnvironmentParameterCount();
+  }
+
+  Register GetEnvironmentParameterRegister(int index) const {
+    return call_descriptor()->GetEnvironmentParameterRegister(index);
+  }
+
+  Representation GetEnvironmentParameterRepresentation(int index) const {
+    return call_descriptor()->GetEnvironmentParameterRepresentation(index);
+  }
+
   ExternalReference miss_handler() const {
     DCHECK(has_miss_handler_);
     return miss_handler_;
   }
 
   bool has_miss_handler() const {
     return has_miss_handler_;
   }
 
   bool IsEnvironmentParameterCountRegister(int index) const {
-    return GetEnvironmentParameterRegister(index).is(stack_parameter_count_);
+    return call_descriptor()->GetEnvironmentParameterRegister(index).is(
+        stack_parameter_count_);
   }
 
   int GetHandlerParameterCount() const {
-    int params = GetEnvironmentParameterCount();
+    int params = call_descriptor()->GetEnvironmentParameterCount();
     if (handler_arguments_mode_ == PASS_ARGUMENTS) {
       params += 1;
     }
     return params;
   }
 
   int hint_stack_parameter_count() const { return hint_stack_parameter_count_; }
   Register stack_parameter_count() const { return stack_parameter_count_; }
   StubFunctionMode function_mode() const { return function_mode_; }
   Address deoptimization_handler() const { return deoptimization_handler_; }
   CodeStub::Major MajorKey() const { return major_; }
 
  private:
+  CallInterfaceDescriptor* call_descriptor_;
   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_;
 
   Address deoptimization_handler_;
   HandlerArgumentsMode handler_arguments_mode_;
 
   ExternalReference miss_handler_;
@@ skipping 317 matching lines @@
     kCallSiteInlineCheck = 1 << 1,
     kReturnTrueFalseObject = 1 << 2
   };
 
   InstanceofStub(Isolate* isolate, Flags flags) : PlatformCodeStub(isolate) {
     minor_key_ = FlagBits::encode(flags);
   }
 
   void Generate(MacroAssembler* masm);
 
-  static Register left();
-  static Register right();
+  static Register left() { return InstanceofConvention::left(); }
+  static Register right() { return InstanceofConvention::right(); }
 
   virtual void InitializeInterfaceDescriptor(
       CodeStubInterfaceDescriptor* descriptor);
 
  private:
   virtual Major MajorKey() const V8_OVERRIDE { return Instanceof; }
 
   Flags flags() const { return FlagBits::decode(minor_key_); }
 
   bool HasArgsInRegisters() const { return (flags() & kArgsInRegisters) != 0; }
@@ skipping 1881 matching lines @@
 
   void Generate(MacroAssembler* masm);
 
   DISALLOW_COPY_AND_ASSIGN(ProfileEntryHookStub);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_CODE_STUBS_H_