Rework CallApi*Stubs.

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 49 matching lines @@
   V(Compare)                                  \
   V(ToBoolean)                                \
   V(BinaryOp)                                 \
   V(BinaryOpWithAllocationSite)               \
   V(StringAdd)                                \
   V(StringCompare)                            \
   V(Keyed)                                    \
   V(Named)                                    \
   V(CallHandler)                              \
   V(ArgumentAdaptor)                          \
-  V(ApiFunction)                              \
-  V(ApiAccessor)                              \
+  V(ApiCallbackWith0Args)                     \
+  V(ApiCallbackWith1Args)                     \
+  V(ApiCallbackWith2Args)                     \
+  V(ApiCallbackWith3Args)                     \
+  V(ApiCallbackWith4Args)                     \
+  V(ApiCallbackWith5Args)                     \
+  V(ApiCallbackWith6Args)                     \
+  V(ApiCallbackWith7Args)                     \
   V(ApiGetter)                                \
   V(LoadGlobalViaContext)                     \
   V(StoreGlobalViaContext)                    \
   V(MathPowTagged)                            \
   V(MathPowInteger)                           \
   V(ContextOnly)                              \
   V(GrowArrayElements)                        \
   V(InterpreterDispatch)                      \
   V(InterpreterPushArgsAndCall)               \
   V(InterpreterPushArgsAndConstruct)          \
@@ skipping 110 matching lines @@
     return BuildDefaultFunctionType(isolate, register_param_count);
   }
 
   virtual void InitializePlatformSpecific(CallInterfaceDescriptorData* data) {
     UNREACHABLE();
   }
 
   void Initialize(Isolate* isolate, CallDescriptors::Key key) {
     if (!data()->IsInitialized()) {
       CallInterfaceDescriptorData* d = isolate->call_descriptor_data(key);
+      DCHECK(d == data());  // d should be a modifiable pointer to data().
       InitializePlatformSpecific(d);
       FunctionType* function_type = BuildCallInterfaceDescriptorFunctionType(
           isolate, d->register_param_count());
       d->InitializePlatformIndependent(function_type);
     }
   }
 
  private:
   const CallInterfaceDescriptorData* data_;
 };
 
+#define DECLARE_DESCRIPTOR_WITH_BASE(name, base)           \
+ public:                                                   \
+  explicit name(Isolate* isolate) : base(isolate, key()) { \
+    Initialize(isolate, key());                            \
+  }                                                        \
+  static inline CallDescriptors::Key key();
 
 #define DECLARE_DESCRIPTOR(name, base)                                         \
-  explicit name(Isolate* isolate) : base(isolate, key()) {                     \
-    Initialize(isolate, key());                                                \
-  }                                                                            \
-                                                                               \
+  DECLARE_DESCRIPTOR_WITH_BASE(name, base)                                     \
  protected:                                                                    \
   void InitializePlatformSpecific(CallInterfaceDescriptorData* data) override; \
   name(Isolate* isolate, CallDescriptors::Key key) : base(isolate, key) {}     \
                                                                                \
- public:                                                                       \
-  static inline CallDescriptors::Key key();
+ public:
 
 #define DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE(name, base) \
   DECLARE_DESCRIPTOR(name, base)                                 \
  protected:                                                      \
   FunctionType* BuildCallInterfaceDescriptorFunctionType(        \
       Isolate* isolate, int register_param_count) override;      \
                                                                  \
  public:
 
 class VoidDescriptor : public CallInterfaceDescriptor {
@@ skipping 447 matching lines @@
   DECLARE_DESCRIPTOR(CallHandlerDescriptor, CallInterfaceDescriptor)
 };
 
 
 class ArgumentAdaptorDescriptor : public CallInterfaceDescriptor {
  public:
   DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE(ArgumentAdaptorDescriptor,
                                                CallInterfaceDescriptor)
 };
 
+// The ApiCallback*Descriptors have a lot of boilerplate. Because
+// - the macros in this file assumes a class name ends in "Descriptor",
+// - the platform-specific part is independent of the number of arguments,
+// - several macros assume static dispatch,
+// we have a regular 'base' class, plus a templated base class for a given
+// number of arguments.
+//
+// Neither 'base' class is meant to be instantiated directly, and neither
+// has public constructors to ensure this is so.
+//
+// The simplest usage for all the ApiCallback*Descriptors is probably
+//   ApiCallbackDescriptorBase::ForArgs(isolate, argc)
+class ApiCallbackDescriptorBase : public CallInterfaceDescriptor {
+ public:
+  static CallInterfaceDescriptor ForArgs(Isolate* isolate, int argc);
 
-class ApiFunctionDescriptor : public CallInterfaceDescriptor {
+ protected:
+  void InitializePlatformSpecific(CallInterfaceDescriptorData* data) override;
+  ApiCallbackDescriptorBase(Isolate* isolate, CallDescriptors::Key key)
+      : CallInterfaceDescriptor(isolate, key) {}
+};
+
+template <int argc>

[danno, 2016/03/04 18:07:43]

Is this template magic really necessary? Can you not just create a new macro
DECLARE_API_CALLBACK_WITH_ARGS_DESCRIPTOR with a integer argument that does that
same? It seems a little less magic.

[vogelheim, 2016/03/08 12:59:27]

Removed, and replaced with DECLARE_DESCRIPTOR_WITH_BASE_AND_FUNCTION_TYPE_ARG.

This does look nicer.

+class ApiCallbackWithArgsBase : public ApiCallbackDescriptorBase {
+ protected:
+  ApiCallbackWithArgsBase(Isolate* isolate, CallDescriptors::Key key)
+      : ApiCallbackDescriptorBase(isolate, key) {}
+  FunctionType* BuildCallInterfaceDescriptorFunctionType(
+      Isolate* isolate, int register_param_count) override;
+};
+
+class ApiCallbackWith0ArgsDescriptor : public ApiCallbackWithArgsBase<0> {
  public:
-  DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE(ApiFunctionDescriptor,
-                                               CallInterfaceDescriptor)
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith0ArgsDescriptor,
+                               ApiCallbackWithArgsBase<0>)
+};
+
+class ApiCallbackWith1ArgsDescriptor : public ApiCallbackWithArgsBase<1> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith1ArgsDescriptor,
+                               ApiCallbackWithArgsBase<1>)
+};
+
+class ApiCallbackWith2ArgsDescriptor : public ApiCallbackWithArgsBase<2> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith2ArgsDescriptor,
+                               ApiCallbackWithArgsBase<2>)
+};
+
+class ApiCallbackWith3ArgsDescriptor : public ApiCallbackWithArgsBase<3> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith3ArgsDescriptor,
+                               ApiCallbackWithArgsBase<3>)
+};
+
+class ApiCallbackWith4ArgsDescriptor : public ApiCallbackWithArgsBase<4> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith4ArgsDescriptor,
+                               ApiCallbackWithArgsBase<4>)
+};
+
+class ApiCallbackWith5ArgsDescriptor : public ApiCallbackWithArgsBase<5> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith5ArgsDescriptor,
+                               ApiCallbackWithArgsBase<5>)
+};
+
+class ApiCallbackWith6ArgsDescriptor : public ApiCallbackWithArgsBase<6> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith6ArgsDescriptor,
+                               ApiCallbackWithArgsBase<6>)
+};
+
+class ApiCallbackWith7ArgsDescriptor : public ApiCallbackWithArgsBase<7> {
+ public:
+  DECLARE_DESCRIPTOR_WITH_BASE(ApiCallbackWith7ArgsDescriptor,
+                               ApiCallbackWithArgsBase<7>)
 };
 
 
-class ApiAccessorDescriptor : public CallInterfaceDescriptor {
- public:
-  DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE(ApiAccessorDescriptor,
-                                               CallInterfaceDescriptor)
-};
-
-
 class ApiGetterDescriptor : public CallInterfaceDescriptor {
  public:
   DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE(ApiGetterDescriptor,
                                                CallInterfaceDescriptor)
 
   static const Register function_address();
 };
 
 
 class MathPowTaggedDescriptor : public CallInterfaceDescriptor {
@@ skipping 20 matching lines @@
 
 class GrowArrayElementsDescriptor : public CallInterfaceDescriptor {
  public:
   DECLARE_DESCRIPTOR(GrowArrayElementsDescriptor, CallInterfaceDescriptor)
 
   enum RegisterInfo { kObjectIndex, kKeyIndex };
   static const Register ObjectRegister();
   static const Register KeyRegister();
 };
 
-class InterpreterDispatchDescriptor  : public CallInterfaceDescriptor {
+class InterpreterDispatchDescriptor : public CallInterfaceDescriptor {
  public:
   DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE(InterpreterDispatchDescriptor,
                                                CallInterfaceDescriptor)
 
   static const int kAccumulatorParameter = 0;
   static const int kRegisterFileParameter = 1;
   static const int kBytecodeOffsetParameter = 2;
   static const int kBytecodeArrayParameter = 3;
   static const int kDispatchTableParameter = 4;
   static const int kContextParameter = 5;
@@ skipping 12 matching lines @@
   DECLARE_DESCRIPTOR(InterpreterPushArgsAndConstructDescriptor,
                      CallInterfaceDescriptor)
 };
 
 
 class InterpreterCEntryDescriptor : public CallInterfaceDescriptor {
  public:
   DECLARE_DESCRIPTOR(InterpreterCEntryDescriptor, CallInterfaceDescriptor)
 };
 
+#undef DECLARE_DESCRIPTOR_WITH_BASE
 #undef DECLARE_DESCRIPTOR
-
+#undef DECLARE_DESCRIPTOR_WITH_CUSTOM_FUNCTION_TYPE
 
 // We define the association between CallDescriptors::Key and the specialized
 // descriptor here to reduce boilerplate and mistakes.
 #define DEF_KEY(name) \
   CallDescriptors::Key name##Descriptor::key() { return CallDescriptors::name; }
 INTERFACE_DESCRIPTOR_LIST(DEF_KEY)
 #undef DEF_KEY
 }  // namespace internal
 }  // namespace v8
 
 
 #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_