Support for return-address rewriting profilers.

src/platform.h

 // 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 238 matching lines @@
   // Support for the profiler.  Can do nothing, in which case ticks
   // occuring in shared libraries will not be properly accounted for.
   static void LogSharedLibraryAddresses();
 
   // Support for the profiler.  Notifies the external profiling
   // process that a code moving garbage collection starts.  Can do
   // nothing, in which case the code objects must not move (e.g., by
   // using --never-compact) if accurate profiling is desired.
   static void SignalCodeMovingGC();
 
+  // Support for profilers that change the return address for functions under
+  // profiling. The input is a pointer to a return address on the stack, and the
+  // return value is either that same pointer, or a pointer to the location
+  // where the profiler has stashed the actual return address.
+  // This is implemented only for the Syzygy instrumenting performance profiler
+  // on Win32 at present.
+#ifdef _WIN32
+  static Address* ResolveReturnAddressLocation(Address* pc_address);
+#else
+  static Address* ResolveReturnAddressLocation(Address* pc_address) {
+    return pc_address;
+  }
+#endif
+
   // The return value indicates the CPU features we are sure of because of the
   // OS.  For example MacOSX doesn't run on any x86 CPUs that don't have SSE2
   // instructions.
   // This is a little messy because the interpretation is subject to the cross
   // of the CPU and the OS.  The bits in the answer correspond to the bit
   // positions indicated by the members of the CpuFeature enum from globals.h
   static uint64_t CpuFeaturesImpliedByPlatform();
 
   // Maximum size of the virtual memory.  0 means there is no artificial
   // limit.
@@ skipping 425 matching lines @@
   Atomic32 active_;
   PlatformData* data_;  // Platform specific data.
   int samples_taken_;  // Counts stack samples taken.
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_