Use a random seed for the string hash algorithm.

src/isolate.cc

 // Copyright 2011 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 1419 matching lines @@
       preallocated_storage_preallocated_(false),
       inner_pointer_to_code_cache_(NULL),
       write_input_buffer_(NULL),
       global_handles_(NULL),
       context_switcher_(NULL),
       thread_manager_(NULL),
       fp_stubs_generated_(false),
       has_installed_extensions_(false),
       string_tracker_(NULL),
       regexp_stack_(NULL),
-      embedder_data_(NULL) {
+      embedder_data_(NULL),
+      hasher_seed_(0) {
   TRACE_ISOLATE(constructor);
 
   memset(isolate_addresses_, 0,
       sizeof(isolate_addresses_[0]) * (kIsolateAddressCount + 1));
 
   heap_.isolate_ = this;
   zone_.isolate_ = this;
   stack_guard_.isolate_ = this;
 
   // ThreadManager is initialized early to support locking an isolate
@@ skipping 275 matching lines @@
   unicode_cache_ = new UnicodeCache();
   inner_pointer_to_code_cache_ = new InnerPointerToCodeCache(this);
   write_input_buffer_ = new StringInputBuffer();
   global_handles_ = new GlobalHandles(this);
   bootstrapper_ = new Bootstrapper();
   handle_scope_implementer_ = new HandleScopeImplementer(this);
   stub_cache_ = new StubCache(this);
   regexp_stack_ = new RegExpStack();
   regexp_stack_->isolate_ = this;
 
+  // Setup the seed that is used to randomize the string hash function.
+  ASSERT(hasher_seed_ == 0);
+  if (FLAG_randomize_string_hashes) {
+    if (FLAG_string_hash_seed == 0) {
+      hasher_seed_ = V8::RandomPrivate(this);
+    } else {
+      hasher_seed_ = FLAG_string_hash_seed;
+    }
+  }
+
   // Enable logging before setting up the heap
   logger_->Setup();
 
   CpuProfiler::Setup();
   HeapProfiler::Setup();
 
   // Initialize other runtime facilities
 #if defined(USE_SIMULATOR)
 #if defined(V8_TARGET_ARCH_ARM) || defined(V8_TARGET_ARCH_MIPS)
   Simulator::Initialize(this);
@@ skipping 155 matching lines @@
 
 #ifdef DEBUG
 #define ISOLATE_FIELD_OFFSET(type, name, ignored)                       \
 const intptr_t Isolate::name##_debug_offset_ = OFFSET_OF(Isolate, name##_);
 ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)
 ISOLATE_INIT_ARRAY_LIST(ISOLATE_FIELD_OFFSET)
 #undef ISOLATE_FIELD_OFFSET
 #endif
 
 } }  // namespace v8::internal