ll_prof: Reduce profiling hooks overhead from >400% to 25%.

src/utils.h

 // Copyright 2006-2008 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 233 matching lines @@
   hash = ~hash + (hash << 15);  // hash = (hash << 15) - hash - 1;
   hash = hash ^ (hash >> 12);
   hash = hash + (hash << 2);
   hash = hash ^ (hash >> 4);
   hash = hash * 2057;  // hash = (hash + (hash << 3)) + (hash << 11);
   hash = hash ^ (hash >> 16);
   return hash;
 }
 
 
+static inline uint32_t ComputePointerHash(void* ptr) {
+  return ComputeIntegerHash(
+      static_cast<uint32_t>(reinterpret_cast<intptr_t>(ptr)));
+}
+
+
 // ----------------------------------------------------------------------------
 // Miscellaneous
 
 // A static resource holds a static instance that can be reserved in
 // a local scope using an instance of Access.  Attempts to re-reserve
 // the instance will cause an error.
 template <typename T>
 class StaticResource {
  public:
   StaticResource() : is_reserved_(false)  {}
@@ skipping 523 matching lines @@
 INLINE(Dest BitCast(const Source& source));
 
 template <class Dest, class Source>
 inline Dest BitCast(const Source& source) {
   return BitCastHelper<Dest, Source>::cast(source);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_UTILS_H_