Rebase GDBJIT interface solely on JITCodeEvent

src/gdb-jit.h

 // Copyright 2010 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_GDB_JIT_H_
 #define V8_GDB_JIT_H_
 
-#include "src/allocation.h"
+#include "src/v8.h"
 
 //
-// Basic implementation of GDB JIT Interface client.
-// GBD JIT Interface is supported in GDB 7.0 and above.
-// Currently on x64 and ia32 architectures and Linux OS are supported.
+// GDB has two ways of interacting with JIT code.  With the "JIT compilation
+// interface", V8 can tell GDB when it emits JIT code.  Unfortunately to do so,
+// it has to create platform-native object files, possibly with platform-native
+// debugging information.  Currently only ELF and Mach-O are supported, which
+// limits this interface to Linux and Mac OS.  This JIT compilation interface
+// was introduced in GDB 7.0.  V8 support can be enabled with the --gdbjit flag.
 //
-
-#ifdef ENABLE_GDB_JIT_INTERFACE
-#include "src/v8.h"
-
-#include "src/factory.h"
+// The other way that GDB can know about V8 code is via the "custom JIT reader"
+// interface, in which a GDB extension parses V8's private data to determine the
+// function, file, and line of a JIT frame, and how to unwind those frames.
+// This interface was introduced in GDB 7.6.  This interface still relies on V8
+// to register its code via the JIT compilation interface, but doesn't require
+// that V8 create ELF images.  Support will be added for this interface in the
+// future.
+//
 
 namespace v8 {
 namespace internal {
-
-class CompilationInfo;
-
-class GDBJITInterface: public AllStatic {
- public:
-  enum CodeTag { NON_FUNCTION, FUNCTION };
-
-  // Main entry point into GDB JIT realized as a JitCodeEventHandler.
-  static void EventHandler(const v8::JitCodeEvent* event);
-
-  static void AddCode(Handle<Name> name,
-                      Handle<Script> script,
-                      Handle<Code> code,
-                      CompilationInfo* info);
-
-  static void RemoveCodeRange(Address start, Address end);
-
- private:
-  static void AddCode(const char* name, Code* code, CodeTag tag, Script* script,
-                      CompilationInfo* info);
-
-  static void RemoveCode(Code* code);
-};
-
-#define GDBJIT(action) GDBJITInterface::action
-
-} }   // namespace v8::internal
-#else
-#define GDBJIT(action) ((void) 0)
+namespace GDBJITInterface {
+#ifdef ENABLE_GDB_JIT_INTERFACE
+// JitCodeEventHandler that creates ELF/Mach-O objects and registers them with
+// GDB.
+void EventHandler(const v8::JitCodeEvent* event);
 #endif
+}  // namespace GDBJITInterface
+}  // namespace internal
+}  // namespace v8
 
 #endif