Implements a new API to set a function entry hook for profiling.

include/v8.h

 // Copyright 2012 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 2897 matching lines @@
  * of entropy.
  */
 typedef bool (*EntropySource)(unsigned char* buffer, size_t length);
 
 
 /**
  * ReturnAddressLocationResolver is used as a callback function when v8 is
  * resolving the location of a return address on the stack. Profilers that
  * change the return address on the stack can use this to resolve the stack
  * location to whereever the profiler stashed the original return address.
- * When invoked, return_addr_location will point to a location on stack where
- * a machine return address resides, this function should return either the
- * same pointer, or a pointer to the profiler's copy of the original return
- * address.
+ *
+ * \param return_addr_location points to a location on stack where a machine
+ *    return address resides.
+ * \returns either return_addr_location, or else a pointer to the profiler's
+ *    copy of the original return address.
+ *
+ * \note the resolver function must not cause garbage collection.
  */
 typedef uintptr_t (*ReturnAddressLocationResolver)(
     uintptr_t return_addr_location);
 
 
 /**
+ * FunctionEntryHook is the type of the profile entry hook called at entry to
+ * any generated function when function-level profiling is enabled.
+ *
+ * \param function the address of the function that's being entered.
+ * \param return_addr_location points to a location on stack where the machine
+ *    return address resides. This can be used to identify the caller of
+ *    \p function, and/or modified to divert execution when \p function exits.
+ *
+ * \note the entry hook must not cause garbage collection.
+ */
+typedef void (*FunctionEntryHook)(uintptr_t function,
+                                  uintptr_t return_addr_location);
+
+
+/**
  * Interface for iterating though all external resources in the heap.
  */
 class V8EXPORT ExternalResourceVisitor {  // NOLINT
  public:
   virtual ~ExternalResourceVisitor() {}
   virtual void VisitExternalString(Handle<String> string) {}
 };
 
 
 /**
@@ skipping 240 matching lines @@
   static void SetEntropySource(EntropySource source);
 
   /**
    * Allows the host application to provide a callback that allows v8 to
    * cooperate with a profiler that rewrites return addresses on stack.
    */
   static void SetReturnAddressLocationResolver(
       ReturnAddressLocationResolver return_address_resolver);
 
   /**
+   * Allows the host application to provide the address of a function that's
+   * invoked on entry to every V8-generated function.
+   * Note that \p entry_hook is invoked at the very start of each
+   * generated function.
+   *
+   * \param entry_hook a function that will be invoked on entry to every
+   *   V8-generated function.
+   * \returns true on success on supported platforms, false on failure.
+   * \note Setting a new entry hook function when one is already active will
+   *   fail.
+   */
+  static bool SetFunctionEntryHook(FunctionEntryHook entry_hook);
+
+  /**
    * Adjusts the amount of registered external memory.  Used to give
    * V8 an indication of the amount of externally allocated memory
    * that is kept alive by JavaScript objects.  V8 uses this to decide
    * when to perform global garbage collections.  Registering
    * externally allocated memory will trigger global garbage
    * collections more often than otherwise in an attempt to garbage
    * collect the JavaScript objects keeping the externally allocated
    * memory alive.
    *
    * \param change_in_bytes the change in externally allocated memory
@@ skipping 1304 matching lines @@
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_