Multiple stubs can point to the same calling convention.

src/interface-descriptors.h

 // Copyright 2014 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_CALL_INTERFACE_DESCRIPTOR_H_
 #define V8_CALL_INTERFACE_DESCRIPTOR_H_
 
 #include "src/assembler.h"
 #include "src/macro-assembler.h"
 
@@ skipping 66 matching lines @@
   // assumed to be Tagged().
   SmartArrayPointer<Representation> register_param_representations_;
 
   PlatformInterfaceDescriptor* platform_specific_descriptor_;
 
   DISALLOW_COPY_AND_ASSIGN(InterfaceDescriptor);
 };
 
 
 enum CallDescriptorKey {
+  LoadICCall,
+  StoreICCall,
+  ElementTransitionAndStoreCall,
+  InstanceofCall,
+  VectorLoadICCall,
+  FastNewClosureCall,
+  FastNewContextCall,
+  ToNumberCall,
+  NumberToStringCall,
+  FastCloneShallowArrayCall,
+  FastCloneShallowObjectCall,
+  CreateAllocationSiteCall,
+  CallFunctionCall,
+  CallConstructCall,
+  RegExpConstructResultCall,
+  TransitionElementsKindCall,
+  ArrayConstructorConstantArgCountCall,
+  ArrayConstructorCall,
+  InternalArrayConstructorConstantArgCountCall,
+  InternalArrayConstructorCall,
+  CompareNilCall,
+  ToBooleanCall,
+  BinaryOpCall,
+  BinaryOpWithAllocationSiteCall,
+  StringAddCall,
   KeyedCall,
   NamedCall,
   CallHandler,
   ArgumentAdaptorCall,
   ApiFunctionCall,
   NUMBER_OF_CALL_DESCRIPTORS
 };
 
 
 class CallInterfaceDescriptor : public InterfaceDescriptor {
  public:
   CallInterfaceDescriptor() {}
 
   // A copy of the passed in registers and param_representations is made
   // and owned by the CallInterfaceDescriptor.
 
   // TODO(mvstanton): Instead of taking parallel arrays register and
   // param_representations, how about a struct that puts the representation
   // and register side by side (eg, RegRep(r1, Representation::Tagged()).
   // The same should go for the CodeStubInterfaceDescriptor class.
   void Initialize(int register_parameter_count, Register* registers,
                   Representation* param_representations,
                   PlatformInterfaceDescriptor* platform_descriptor = NULL);
 };
 
 
 class CallDescriptors {
  public:
   static void InitializeForIsolate(Isolate* isolate);
+
+ private:
+  static void InitializeForIsolateAllPlatforms(Isolate* isolate);
 };
 }
 }  // namespace v8::internal
 
 #if V8_TARGET_ARCH_ARM64
 #include "src/arm64/interface-descriptors-arm64.h"
 #elif V8_TARGET_ARCH_ARM
 #include "src/arm/interface-descriptors-arm.h"
 #endif
 
 #endif  // V8_CALL_INTERFACE_DESCRIPTOR_H_