Direct call api functions (arm implementation)

src/arm/code-stubs-arm.h

 // Copyright 2010 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 438 matching lines @@
   RegExpCEntryStub() {}
   virtual ~RegExpCEntryStub() {}
   void Generate(MacroAssembler* masm);
 
  private:
   Major MajorKey() { return RegExpCEntry; }
   int MinorKey() { return 0; }
   const char* GetName() { return "RegExpCEntryStub"; }
 };
 
+// Stub used when returning from direct native call to generated code.

[antonm, 2011/01/21 17:56:36]

English is not native to me, so feel free to ignore.

May you rework the comment?  It's not obvious what's the difference between the
code stub and the stub is.

Maybe something along these lines: "Trampoline stub to call into native
code.\n\nTo call safely into native code in the presence of compacting GC (which
can move code objects) we need to keep the code which called into native pinned
in the memory.  Currently the simplest approach is to generate such stub early
enough so it can never be moved by GC".

My wording is far from perfect, just a stub :)

[Zaheer, 2011/01/24 09:43:31]

Thanks. I think your description is more accurate and complete.
Done.

+// Allows the code stub to move in case of a GC from the native call.
+// The stub itself is assumed to be unmovable.
+class DirectCEntryStub: public CodeStub {
+ public:
+  DirectCEntryStub() {}
+  void Generate(MacroAssembler* masm);
+
+ private:
+  Major MajorKey() { return DirectCEntry; }
+  int MinorKey() { return 0; }
+  const char* GetName() { return "DirectCEntryStub"; }
+};
+
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_CODE_STUBS_ARM_H_