[Isolates] Merge crankshaft (r5922 from bleeding_edge).

src/runtime-profiler.h

+// Copyright 2010 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_RUNTIME_PROFILER_H_
+#define V8_RUNTIME_PROFILER_H_
+
+#include "allocation.h"
+#include "atomicops.h"
+
+namespace v8 {
+namespace internal {
+
+class Isolate;
+class JSFunction;
+class Object;
+class PendingListNode;
+class Semaphore;
+
+class RuntimeProfiler {
+ public:
+  explicit RuntimeProfiler(Isolate* isolate);
+
+  static bool IsEnabled();
+
+  void OptimizeNow();
+  void OptimizeSoon(JSFunction* function);
+
+  void NotifyTick();
+
+  void Setup();
+  void Reset();
+  void TearDown();
+
+  void MarkCompactPrologue(bool is_compacting);
+  Object** SamplerWindowAddress();
+  int SamplerWindowSize();
+
+  // Rate limiting support.
+
+  // VM thread interface.
+  //
+  // Called by isolates when their states change.
+  static inline void IsolateEnteredJS(Isolate* isolate);
+  static inline void IsolateExitedJS(Isolate* isolate);
+
+  // Profiler thread interface.
+  //
+  // IsSomeIsolateInJS():
+  // The profiler thread can query whether some isolate is currently
+  // running JavaScript code.
+  //
+  // WaitForSomeIsolateToEnterJS():
+  // When no isolates are running JavaScript code for some time the
+  // profiler thread suspends itself by calling the wait function. The
+  // wait function returns true after it waited or false immediately.
+  // While the function was waiting the profiler may have been
+  // disabled so it *must check* whether it is allowed to continue.
+  static bool IsSomeIsolateInJS();
+  static bool WaitForSomeIsolateToEnterJS();
+
+  // When shutting down we join the profiler thread. Doing so while
+  // it's waiting on a semaphore will cause a deadlock, so we have to
+  // wake it up first.
+  static void WakeUpRuntimeProfilerThreadBeforeShutdown();
+
+ private:
+  static const int kSamplerWindowSize = 16;
+
+  static void HandleWakeUp(Isolate* isolate);
+
+  void Optimize(JSFunction* function, bool eager, int delay);
+
+  void AttemptOnStackReplacement(JSFunction* function);
+
+  void ClearSampleBuffer();
+
+  void ClearSampleBufferNewSpaceEntries();
+
+  int LookupSample(JSFunction* function);
+
+  void AddSample(JSFunction* function, int weight);
+
+  Isolate* isolate_;
+
+  int sampler_threshold_;
+  int sampler_threshold_size_factor_;
+
+  // The JSFunctions in the sampler window are not GC safe. Old-space
+  // pointers are not cleared during mark-sweep collection and therefore
+  // the window might contain stale pointers. The window is updated on
+  // scavenges and (parts of it) cleared on mark-sweep and
+  // mark-sweep-compact.
+  JSFunction* sampler_window_[kSamplerWindowSize];
+  int sampler_window_position_;
+  int sampler_window_weight_[kSamplerWindowSize];
+
+  // Support for pending 'optimize soon' requests.
+  PendingListNode* optimize_soon_list_;
+
+  // Possible state values:
+  //   -1            => the profiler thread is waiting on the semaphore
+  //   0 or positive => the number of isolates running JavaScript code.
+  static Atomic32 state_;
+  static Semaphore* semaphore_;
+};
+
+
+// Rate limiter intended to be used in the profiler thread.
+class RuntimeProfilerRateLimiter BASE_EMBEDDED {
+ public:
+  RuntimeProfilerRateLimiter() : non_js_ticks_(0) { }
+
+  // Suspends the current thread (which must be the profiler thread)
+  // when not executing JavaScript to minimize CPU usage. Returns
+  // whether the thread was suspended (and so must check whether
+  // profiling is still active.)
+  //
+  // Does nothing when runtime profiling is not enabled.
+  bool SuspendIfNecessary();
+
+ private:
+  int non_js_ticks_;
+
+  DISALLOW_COPY_AND_ASSIGN(RuntimeProfilerRateLimiter);
+};
+
+
+// Implementation of RuntimeProfiler inline functions.
+
+void RuntimeProfiler::IsolateEnteredJS(Isolate* isolate) {
+  Atomic32 new_state = NoBarrier_AtomicIncrement(&state_, 1);
+  if (new_state == 0) {
+    // Just incremented from -1 to 0. -1 can only be set by the
+    // profiler thread before it suspends itself and starts waiting on
+    // the semaphore.
+    HandleWakeUp(isolate);
+  }
+  ASSERT(new_state >= 0);
+}
+
+
+void RuntimeProfiler::IsolateExitedJS(Isolate* isolate) {
+  Atomic32 new_state = NoBarrier_AtomicIncrement(&state_, -1);
+  ASSERT(new_state >= 0);
+  USE(new_state);
+}
+
+} }  // namespace v8::internal
+
+#endif  // V8_RUNTIME_PROFILER_H_