Implement glue for V8 JIT code profiling.

base/debug/profiler.h

Index: base/debug/profiler.h
diff --git a/base/debug/profiler.h b/base/debug/profiler.h
index d703876b4df5d0151bf0c05ca021de33cc66c12a..2f08a677b78d0e1bd97d78cc3b2585754a6cc575 100644
--- a/base/debug/profiler.h
+++ b/base/debug/profiler.h
@@ -1,67 +1,90 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef BASE_DEBUG_PROFILER_H
-#define BASE_DEBUG_PROFILER_H
-
-#include <string>
-
-#include "base/base_export.h"
-#include "base/basictypes.h"
-
-// The Profiler functions allow usage of the underlying sampling based
-// profiler. If the application has not been built with the necessary
-// flags (-DENABLE_PROFILING and not -DNO_TCMALLOC) then these functions
-// are noops.
-namespace base {
-namespace debug {
-
-// Start profiling with the supplied name.
-// {pid} will be replaced by the process' pid and {count} will be replaced
-// by the count of the profile run (starts at 1 with each process).
-BASE_EXPORT void StartProfiling(const std::string& name);
-
-// Stop profiling and write out data.
-BASE_EXPORT void StopProfiling();
-
-// Force data to be written to file.
-BASE_EXPORT void FlushProfiling();
-
-// Returns true if process is being profiled.
-BASE_EXPORT bool BeingProfiled();
-
-// Reset profiling after a fork, which disables timers.
-BASE_EXPORT void RestartProfilingAfterFork();
-
-// Returns true iff this executable is instrumented with the Syzygy profiler.
-BASE_EXPORT bool IsBinaryInstrumented();
-
-// There's a class of profilers that use "return address swizzling" to get a
-// hook on function exits. This class of profilers uses some form of entry hook,
-// like e.g. binary instrumentation, or a compiler flag, that calls a hook each
-// time a function is invoked. The hook then switches the return address on the
-// stack for the address of an exit hook function, and pushes the original
-// return address to a shadow stack of some type. When in due course the CPU
-// executes a return to the exit hook, the exit hook will do whatever work it
-// does on function exit, then arrange to return to the original return address.
-// This class of profiler does not play well with programs that look at the
-// return address, as does e.g. V8. V8 uses the return address to certain
-// runtime functions to find the JIT code that called it, and from there finds
-// the V8 data structures associated to the JS function involved.
-// A return address resolution function is used to fix this. It allows such
-// programs to resolve a location on stack where a return address originally
-// resided, to the shadow stack location where the profiler stashed it.
-typedef uintptr_t (*ReturnAddressLocationResolver)(
-    uintptr_t return_addr_location);
-
-// If this binary is instrumented and the instrumentation supplies a return
-// address resolution function, finds and returns the address resolution
-// function. Otherwise returns NULL.
-BASE_EXPORT ReturnAddressLocationResolver
-    GetProfilerReturnAddrResolutionFunc();
-
-}  // namespace debug
-}  // namespace base
-
-#endif  // BASE_DEBUG_DEBUGGER_H
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_DEBUG_PROFILER_H
+#define BASE_DEBUG_PROFILER_H
+
+#include <string>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+
+// The Profiler functions allow usage of the underlying sampling based
+// profiler. If the application has not been built with the necessary
+// flags (-DENABLE_PROFILING and not -DNO_TCMALLOC) then these functions
+// are noops.
+namespace base {
+namespace debug {
+
+// Start profiling with the supplied name.
+// {pid} will be replaced by the process' pid and {count} will be replaced
+// by the count of the profile run (starts at 1 with each process).
+BASE_EXPORT void StartProfiling(const std::string& name);
+
+// Stop profiling and write out data.
+BASE_EXPORT void StopProfiling();
+
+// Force data to be written to file.
+BASE_EXPORT void FlushProfiling();
+
+// Returns true if process is being profiled.
+BASE_EXPORT bool BeingProfiled();
+
+// Reset profiling after a fork, which disables timers.
+BASE_EXPORT void RestartProfilingAfterFork();
+
+// Returns true iff this executable is instrumented with the Syzygy profiler.
+BASE_EXPORT bool IsBinaryInstrumented();
+
+// There's a class of profilers that use "return address swizzling" to get a
+// hook on function exits. This class of profilers uses some form of entry hook,
+// like e.g. binary instrumentation, or a compiler flag, that calls a hook each
+// time a function is invoked. The hook then switches the return address on the
+// stack for the address of an exit hook function, and pushes the original
+// return address to a shadow stack of some type. When in due course the CPU
+// executes a return to the exit hook, the exit hook will do whatever work it
+// does on function exit, then arrange to return to the original return address.
+// This class of profiler does not play well with programs that look at the
+// return address, as does e.g. V8. V8 uses the return address to certain
+// runtime functions to find the JIT code that called it, and from there finds
+// the V8 data structures associated to the JS function involved.
+// A return address resolution function is used to fix this. It allows such
+// programs to resolve a location on stack where a return address originally
+// resided, to the shadow stack location where the profiler stashed it.
+typedef uintptr_t (*ReturnAddressLocationResolver)(
+    uintptr_t return_addr_location);
+
+// This type declaration must match V8's FunctionEntryHook.
+typedef void (*DynamicFunctionEntryHook)(uintptr_t function,
+                                         uintptr_t return_addr_location);
+
+// The functions below here are to support profiling V8-generated code.
+// V8 has provisions for generating a call to an entry hook for newly generated
+// JIT code, and it can push symbol information on code generation and advise
+// when the garbage collector moves code. The functions declarations below here
+// make glue between V8's facilities and a profiler.
+
+// This type declaration must match V8's FunctionEntryHook.
+typedef void (*DynamicFunctionEntryHook)(uintptr_t function,
+                                         uintptr_t return_addr_location);
+
+typedef void (*AddDynamicSymbol)(const void* address,
+                                 size_t length,
+                                 const char* name,
+                                 size_t name_len);
+typedef void (*MoveDynamicSymbol)(const void* address, const void* new_address);
+
+
+// If this binary is instrumented and the instrumentation supplies a function
+// for each of those purposes, find and return the function in question.
+// Otherwise returns NULL.
+BASE_EXPORT ReturnAddressLocationResolver GetProfilerReturnAddrResolutionFunc();
+BASE_EXPORT DynamicFunctionEntryHook GetProfilerDynamicFunctionEntryHookFunc();
+BASE_EXPORT AddDynamicSymbol GetProfilerAddDynamicSymbolFunc();
+BASE_EXPORT MoveDynamicSymbol GetProfilerMoveDynamicSymbolFunc();
+
+}  // namespace debug
+}  // namespace base
+
+#endif  // BASE_DEBUG_DEBUGGER_H