A64: Synchronize with r16489.

src/sampler.cc

Index: src/sampler.cc
diff --git a/src/sampler.cc b/src/sampler.cc
index f0d2b10c7f7e0d5d150c1d5552426dbaa2f64032..ef525f96faf870a14422cadab343eb7ccbc03d00 100644
--- a/src/sampler.cc
+++ b/src/sampler.cc
@@ -27,9 +27,7 @@
 
 #include "sampler.h"
 
-#if defined(__linux__) || defined(__FreeBSD__) || defined(__OpenBSD__) \
-    || defined(__NetBSD__) || defined(__sun) || defined(__ANDROID__) \
-    || defined(__native_client__) || defined(__MACH__)
+#if V8_OS_POSIX && !V8_OS_CYGWIN
 
 #define USE_SIGNALS
 
@@ -39,25 +37,25 @@
 #include <sys/time.h>
 #include <sys/syscall.h>
 
-#if defined(__MACH__)
+#if V8_OS_MACOSX
 #include <mach/mach.h>
 // OpenBSD doesn't have <ucontext.h>. ucontext_t lives in <signal.h>
 // and is a typedef for struct sigcontext. There is no uc_mcontext.
-#elif(!defined(__ANDROID__) || defined(__BIONIC_HAVE_UCONTEXT_T)) \
-    && !defined(__OpenBSD__)
+#elif(!V8_OS_ANDROID || defined(__BIONIC_HAVE_UCONTEXT_T)) \
+    && !V8_OS_OPENBSD
 #include <ucontext.h>
 #endif
 #include <unistd.h>
 
 // GLibc on ARM defines mcontext_t has a typedef for 'struct sigcontext'.
 // Old versions of the C library <signal.h> didn't define the type.
-#if defined(__ANDROID__) && !defined(__BIONIC_HAVE_UCONTEXT_T) && \
+#if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T) && \
     (defined(__arm__) || defined(__aarch64__)) && \
     !defined(__BIONIC_HAVE_STRUCT_SIGCONTEXT)
 #include <asm/sigcontext.h>
 #endif
 
-#elif defined(_WIN32) || defined(_WIN64) || defined(__CYGWIN__)
+#elif V8_OS_WIN || V8_OS_CYGWIN
 
 #include "win32-headers.h"
 
@@ -75,7 +73,7 @@
 #include "vm-state-inl.h"
 
 
-#if defined(__ANDROID__) && !defined(__BIONIC_HAVE_UCONTEXT_T)
+#if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T)
 
 // Not all versions of Android's C library provide ucontext_t.
 // Detect this and provide custom but compatible definitions. Note that these
@@ -159,7 +157,7 @@ typedef struct ucontext {
 enum { REG_EBP = 6, REG_ESP = 7, REG_EIP = 14 };
 #endif
 
-#endif  // __ANDROID__ && !defined(__BIONIC_HAVE_UCONTEXT_T)
+#endif  // V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T)
 
 
 namespace v8 {
@@ -192,7 +190,7 @@ class Sampler::PlatformData : public PlatformDataCommon {
   pthread_t vm_tid_;
 };
 
-#elif defined(_WIN32) || defined(_WIN64) || defined(__CYGWIN__)
+#elif V8_OS_WIN || V8_OS_CYGWIN
 
 // ----------------------------------------------------------------------------
 // Win32 profiler support. On Cygwin we use the same sampler implementation as
@@ -277,8 +275,25 @@ class SimulatorHelper {
 
 class SignalHandler : public AllStatic {
  public:
-  static inline void EnsureInstalled() {
-    if (signal_handler_installed_) return;
+  static void SetUp() { if (!mutex_) mutex_ = new Mutex(); }
+  static void TearDown() { delete mutex_; }
+
+  static void IncreaseSamplerCount() {
+    LockGuard<Mutex> lock_guard(mutex_);
+    if (++client_count_ == 1) Install();
+  }
+
+  static void DecreaseSamplerCount() {
+    LockGuard<Mutex> lock_guard(mutex_);
+    if (--client_count_ == 0) Restore();
+  }
+
+  static bool Installed() {
+    return signal_handler_installed_;
+  }
+
+ private:
+  static void Install() {
     struct sigaction sa;
     sa.sa_sigaction = &HandleProfilerSignal;
     sigemptyset(&sa.sa_mask);
@@ -287,30 +302,31 @@ class SignalHandler : public AllStatic {
         (sigaction(SIGPROF, &sa, &old_signal_handler_) == 0);
   }
 
-  static inline void Restore() {
+  static void Restore() {
     if (signal_handler_installed_) {
       sigaction(SIGPROF, &old_signal_handler_, 0);
       signal_handler_installed_ = false;
     }
   }
 
-  static inline bool Installed() {
-    return signal_handler_installed_;
-  }
-
- private:
   static void HandleProfilerSignal(int signal, siginfo_t* info, void* context);
+  // Protects the process wide state below.
+  static Mutex* mutex_;
+  static int client_count_;
   static bool signal_handler_installed_;
   static struct sigaction old_signal_handler_;
 };
 
+
+Mutex* SignalHandler::mutex_ = NULL;
+int SignalHandler::client_count_ = 0;
 struct sigaction SignalHandler::old_signal_handler_;
 bool SignalHandler::signal_handler_installed_ = false;
 
 
 void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
                                          void* context) {
-#if defined(__native_client__)
+#if V8_OS_NACL
   // As Native Client does not support signal handling, profiling
   // is disabled.
   return;
@@ -328,7 +344,7 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
   }
 
   Sampler* sampler = isolate->logger()->sampler();
-  if (sampler == NULL || !sampler->IsActive()) return;
+  if (sampler == NULL) return;
 
   RegisterState state;
 
@@ -344,10 +360,10 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
 #else
   // Extracting the sample from the context is extremely machine dependent.
   ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
-#if !defined(__OpenBSD__)
+#if !V8_OS_OPENBSD
   mcontext_t& mcontext = ucontext->uc_mcontext;
 #endif
-#if defined(__linux__) || defined(__ANDROID__)
+#if V8_OS_LINUX
 #if V8_HOST_ARCH_IA32
   state.pc = reinterpret_cast<Address>(mcontext.gregs[REG_EIP]);
   state.sp = reinterpret_cast<Address>(mcontext.gregs[REG_ESP]);
@@ -380,7 +396,7 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
   state.sp = reinterpret_cast<Address>(mcontext.gregs[29]);
   state.fp = reinterpret_cast<Address>(mcontext.gregs[30]);
 #endif  // V8_HOST_ARCH_*
-#elif defined(__MACH__)
+#elif V8_OS_MACOSX
 #if V8_HOST_ARCH_X64
 #if __DARWIN_UNIX03
   state.pc = reinterpret_cast<Address>(mcontext->__ss.__rip);
@@ -402,7 +418,7 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
   state.fp = reinterpret_cast<Address>(mcontext->ss.ebp);
 #endif  // __DARWIN_UNIX03
 #endif  // V8_HOST_ARCH_IA32
-#elif defined(__FreeBSD__)
+#elif V8_OS_FREEBSD
 #if V8_HOST_ARCH_IA32
   state.pc = reinterpret_cast<Address>(mcontext.mc_eip);
   state.sp = reinterpret_cast<Address>(mcontext.mc_esp);
@@ -416,7 +432,7 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
   state.sp = reinterpret_cast<Address>(mcontext.mc_r13);
   state.fp = reinterpret_cast<Address>(mcontext.mc_r11);
 #endif  // V8_HOST_ARCH_*
-#elif defined(__NetBSD__)
+#elif V8_OS_NETBSD
 #if V8_HOST_ARCH_IA32
   state.pc = reinterpret_cast<Address>(mcontext.__gregs[_REG_EIP]);
   state.sp = reinterpret_cast<Address>(mcontext.__gregs[_REG_ESP]);
@@ -426,7 +442,7 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
   state.sp = reinterpret_cast<Address>(mcontext.__gregs[_REG_RSP]);
   state.fp = reinterpret_cast<Address>(mcontext.__gregs[_REG_RBP]);
 #endif  // V8_HOST_ARCH_*
-#elif defined(__OpenBSD__)
+#elif V8_OS_OPENBSD
 #if V8_HOST_ARCH_IA32
   state.pc = reinterpret_cast<Address>(ucontext->sc_eip);
   state.sp = reinterpret_cast<Address>(ucontext->sc_esp);
@@ -436,14 +452,14 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
   state.sp = reinterpret_cast<Address>(ucontext->sc_rsp);
   state.fp = reinterpret_cast<Address>(ucontext->sc_rbp);
 #endif  // V8_HOST_ARCH_*
-#elif defined(__sun)
+#elif V8_OS_SOLARIS
   state.pc = reinterpret_cast<Address>(mcontext.gregs[REG_PC]);
   state.sp = reinterpret_cast<Address>(mcontext.gregs[REG_SP]);
   state.fp = reinterpret_cast<Address>(mcontext.gregs[REG_FP]);
-#endif  // __sun
+#endif  // V8_OS_SOLARIS
 #endif  // USE_SIMULATOR
   sampler->SampleStack(state);
-#endif  // __native_client__
+#endif  // V8_OS_NACL
 }
 
 #endif
@@ -457,12 +473,12 @@ class SamplerThread : public Thread {
       : Thread(Thread::Options("SamplerThread", kSamplerThreadStackSize)),
         interval_(interval) {}
 
-  static void SetUp() { if (!mutex_) mutex_ = OS::CreateMutex(); }
-  static void TearDown() { delete mutex_; }
+  static void SetUp() { if (!mutex_) mutex_ = new Mutex(); }
+  static void TearDown() { delete mutex_; mutex_ = NULL; }
 
   static void AddActiveSampler(Sampler* sampler) {
     bool need_to_start = false;
-    ScopedLock lock(mutex_);
+    LockGuard<Mutex> lock_guard(mutex_);
     if (instance_ == NULL) {
       // Start a thread that will send SIGPROF signal to VM threads,
       // when CPU profiling will be enabled.
@@ -475,16 +491,13 @@ class SamplerThread : public Thread {
     ASSERT(instance_->interval_ == sampler->interval());
     instance_->active_samplers_.Add(sampler);
 
-#if defined(USE_SIGNALS)
-    SignalHandler::EnsureInstalled();
-#endif
     if (need_to_start) instance_->StartSynchronously();
   }
 
   static void RemoveActiveSampler(Sampler* sampler) {
     SamplerThread* instance_to_remove = NULL;
     {
-      ScopedLock lock(mutex_);
+      LockGuard<Mutex> lock_guard(mutex_);
 
       ASSERT(sampler->IsActive());
       bool removed = instance_->active_samplers_.RemoveElement(sampler);
@@ -496,9 +509,6 @@ class SamplerThread : public Thread {
       if (instance_->active_samplers_.is_empty()) {
         instance_to_remove = instance_;
         instance_ = NULL;
-#if defined(USE_SIGNALS)
-        SignalHandler::Restore();
-#endif
       }
     }
 
@@ -511,7 +521,7 @@ class SamplerThread : public Thread {
   virtual void Run() {
     while (true) {
       {
-        ScopedLock lock(mutex_);
+        LockGuard<Mutex> lock_guard(mutex_);
         if (active_samplers_.is_empty()) break;
         // When CPU profiling is enabled both JavaScript and C++ code is
         // profiled. We must not suspend.
@@ -587,12 +597,18 @@ DISABLE_ASAN void TickSample::Init(Isolate* isolate,
 
 
 void Sampler::SetUp() {
+#if defined(USE_SIGNALS)
+  SignalHandler::SetUp();
+#endif
   SamplerThread::SetUp();
 }
 
 
 void Sampler::TearDown() {
   SamplerThread::TearDown();
+#if defined(USE_SIGNALS)
+  SignalHandler::TearDown();
+#endif
 }
 
 
@@ -628,6 +644,22 @@ void Sampler::Stop() {
 }
 
 
+void Sampler::IncreaseProfilingDepth() {
+  NoBarrier_AtomicIncrement(&profiling_, 1);
+#if defined(USE_SIGNALS)
+  SignalHandler::IncreaseSamplerCount();
+#endif
+}
+
+
+void Sampler::DecreaseProfilingDepth() {
+#if defined(USE_SIGNALS)
+  SignalHandler::DecreaseSamplerCount();
+#endif
+  NoBarrier_AtomicIncrement(&profiling_, -1);
+}
+
+
 void Sampler::SampleStack(const RegisterState& state) {
   TickSample* sample = isolate_->cpu_profiler()->StartTickSample();
   TickSample sample_obj;
@@ -645,15 +677,6 @@ void Sampler::SampleStack(const RegisterState& state) {
 }
 
 
-bool Sampler::CanSampleOnProfilerEventsProcessorThread() {
-#if defined(USE_SIGNALS)
-  return true;
-#else
-  return false;
-#endif
-}
-
-
 #if defined(USE_SIGNALS)
 
 void Sampler::DoSample() {
@@ -661,7 +684,7 @@ void Sampler::DoSample() {
   pthread_kill(platform_data()->vm_tid(), SIGPROF);
 }
 
-#elif defined(_WIN32) || defined(_WIN64) || defined(__CYGWIN__)
+#elif V8_OS_WIN || V8_OS_CYGWIN
 
 void Sampler::DoSample() {
   HANDLE profiled_thread = platform_data()->profiled_thread();