Allow platforms (linux and win32) to not force 16-byte alignment...

src/platform-macos.cc

 // 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 282 matching lines @@
   if (memory_) munmap(memory_, size_);
   fclose(file_);
 }
 
 
 void OS::LogSharedLibraryAddresses() {
   // TODO(1233579): Implement.
 }
 
 
-double OS::nan_value() { return NAN; }
+double OS::nan_value() {
+  return NAN;
+}
+
+
+int OS::ActivationFrameAlignment() {
+  // OS X activation frames must be 16 byte-aligned; see "Mac OS X ABI
+  // Function Call Guide".
+  return 16;
+}
 
 
 int OS::StackWalk(StackFrame* frames, int frames_size) {
 #ifndef MAC_OS_X_VERSION_10_5
   return 0;
 #else
   void** addresses = NewArray<void*>(frames_size);
   int frames_count = backtrace(addresses, frames_size);
 
   char** symbols;
@@ skipping 320 matching lines @@
   }
 
   // This sampler is no longer the active sampler.
   active_sampler_ = NULL;
   active_ = false;
 }
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal