add stub for api function calls with known number of parameters

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index 4fa440bb70658f9131bf71d36e674a9623b50ef4..03075d92372fe7da40c6244ab42d0c2cd3e80b38 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -1153,7 +1153,18 @@ class CallApiAccessorStub : public PlatformCodeStub {
   CallApiAccessorStub(Isolate* isolate, bool is_store, bool call_data_undefined)
       : PlatformCodeStub(isolate) {
     minor_key_ = IsStoreBits::encode(is_store) |
-                 CallDataUndefinedBits::encode(call_data_undefined);
+                 CallDataUndefinedBits::encode(call_data_undefined) |
+                 ArgumentBits::encode(is_store ? 1 : 0);
+  }
+
+ protected:
+  // For CallApiFunctionWithFixedArgsStub, see below.
+  static const int kArgBits = 3;
+  CallApiAccessorStub(Isolate* isolate, int argc, bool call_data_undefined)
+      : PlatformCodeStub(isolate) {
+    minor_key_ = IsStoreBits::encode(false) |
+                 CallDataUndefinedBits::encode(call_data_undefined) |
+                 ArgumentBits::encode(argc);
   }
 
  private:
@@ -1161,15 +1172,35 @@ class CallApiAccessorStub : public PlatformCodeStub {
   bool call_data_undefined() const {
     return CallDataUndefinedBits::decode(minor_key_);
   }
+  int argc() const { return ArgumentBits::decode(minor_key_); }
 
   class IsStoreBits: public BitField<bool, 0, 1> {};
   class CallDataUndefinedBits: public BitField<bool, 1, 1> {};
+  class ArgumentBits : public BitField<int, 2, kArgBits> {};
 
   DEFINE_CALL_INTERFACE_DESCRIPTOR(ApiAccessor);
   DEFINE_PLATFORM_CODE_STUB(CallApiAccessor, PlatformCodeStub);
 };
 
 
+// TODO(dcarney): see if it's possible to remove this later without performance
+// degradation.
+// This is not a real stub, but a way of generating the CallApiAccessorStub
+// (which has the same abi) which makes it clear that it is not an accessor.
+class CallApiFunctionWithFixedArgsStub : public CallApiAccessorStub {
+ public:
+  static const int kMaxFixedArgs = (1 << kArgBits) - 1;
+  CallApiFunctionWithFixedArgsStub(Isolate* isolate, int argc,
+                                   bool call_data_undefined)
+      : CallApiAccessorStub(isolate, argc, call_data_undefined) {
+    DCHECK(0 <= argc && argc <= kMaxFixedArgs);
+  }
+};
+
+
+typedef ApiAccessorDescriptor ApiFunctionWithFixedArgsDescriptor;
+
+
 class CallApiGetterStub : public PlatformCodeStub {
  public:
   explicit CallApiGetterStub(Isolate* isolate) : PlatformCodeStub(isolate) {}