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diff --git a/tools/profiler/core/platform-win32.cpp b/tools/profiler/core/platform-win32.cpp
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+++ b/tools/profiler/core/platform-win32.cpp
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+// Copyright (c) 2006-2011 The Chromium 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.
+
+#include <windows.h>
+#include <mmsystem.h>
+#include <process.h>
+
+#include "nsWindowsDllInterceptor.h"
+#include "mozilla/StackWalk_windows.h"
+#include "mozilla/WindowsVersion.h"
+
+int profiler_current_process_id() { return _getpid(); }
+
+int profiler_current_thread_id() {
+  DWORD threadId = GetCurrentThreadId();
+  MOZ_ASSERT(threadId <= INT32_MAX, "native thread ID is > INT32_MAX");
+  return int(threadId);
+}
+
+void* GetStackTop(void* aGuess) {
+  PNT_TIB pTib = reinterpret_cast<PNT_TIB>(NtCurrentTeb());
+  return reinterpret_cast<void*>(pTib->StackBase);
+}
+
+static void PopulateRegsFromContext(Registers& aRegs, CONTEXT* aContext) {
+#if defined(GP_ARCH_amd64)
+  aRegs.mPC = reinterpret_cast<Address>(aContext->Rip);
+  aRegs.mSP = reinterpret_cast<Address>(aContext->Rsp);
+  aRegs.mFP = reinterpret_cast<Address>(aContext->Rbp);
+#elif defined(GP_ARCH_x86)
+  aRegs.mPC = reinterpret_cast<Address>(aContext->Eip);
+  aRegs.mSP = reinterpret_cast<Address>(aContext->Esp);
+  aRegs.mFP = reinterpret_cast<Address>(aContext->Ebp);
+#elif defined(GP_ARCH_arm64)
+  aRegs.mPC = reinterpret_cast<Address>(aContext->Pc);
+  aRegs.mSP = reinterpret_cast<Address>(aContext->Sp);
+  aRegs.mFP = reinterpret_cast<Address>(aContext->Fp);
+#else
+#  error "bad arch"
+#endif
+  aRegs.mLR = 0;
+}
+
+// Gets a real (i.e. not pseudo) handle for the current thread, with the
+// permissions needed for profiling.
+// @return a real HANDLE for the current thread.
+static HANDLE GetRealCurrentThreadHandleForProfiling() {
+  HANDLE realCurrentThreadHandle;
+  if (!::DuplicateHandle(
+          ::GetCurrentProcess(), ::GetCurrentThread(), ::GetCurrentProcess(),
+          &realCurrentThreadHandle,
+          THREAD_GET_CONTEXT | THREAD_SUSPEND_RESUME | THREAD_QUERY_INFORMATION,
+          FALSE, 0)) {
+    return nullptr;
+  }
+
+  return realCurrentThreadHandle;
+}
+
+class PlatformData {
+ public:
+  // Get a handle to the calling thread. This is the thread that we are
+  // going to profile. We need a real handle because we are going to use it in
+  // the sampler thread.
+  explicit PlatformData(int aThreadId)
+      : mProfiledThread(GetRealCurrentThreadHandleForProfiling()) {
+    MOZ_ASSERT(aThreadId == ::GetCurrentThreadId());
+    MOZ_COUNT_CTOR(PlatformData);
+  }
+
+  ~PlatformData() {
+    if (mProfiledThread != nullptr) {
+      CloseHandle(mProfiledThread);
+      mProfiledThread = nullptr;
+    }
+    MOZ_COUNT_DTOR(PlatformData);
+  }
+
+  HANDLE ProfiledThread() { return mProfiledThread; }
+
+  RunningTimes& PreviousThreadRunningTimesRef() {
+    return mPreviousThreadRunningTimes;
+  }
+
+ private:
+  HANDLE mProfiledThread;
+  RunningTimes mPreviousThreadRunningTimes;
+};
+
+#if defined(USE_MOZ_STACK_WALK)
+HANDLE
+GetThreadHandle(PlatformData* aData) { return aData->ProfiledThread(); }
+#endif
+
+static const HANDLE kNoThread = INVALID_HANDLE_VALUE;
+
+////////////////////////////////////////////////////////////////////////
+// BEGIN Sampler target specifics
+
+Sampler::Sampler(PSLockRef aLock) {}
+
+void Sampler::Disable(PSLockRef aLock) {}
+
+static void StreamMetaPlatformSampleUnits(PSLockRef aLock,
+                                          SpliceableJSONWriter& aWriter) {
+  aWriter.StringProperty("threadCPUDelta", "variable CPU cycles");
+}
+
+static RunningTimes GetThreadRunningTimesDiff(
+    PSLockRef aLock, const RegisteredThread& aRegisteredThread) {
+  AUTO_PROFILER_STATS(GetRunningTimes);
+
+  PlatformData* const platformData = aRegisteredThread.GetPlatformData();
+  MOZ_RELEASE_ASSERT(platformData);
+  const HANDLE profiledThread = platformData->ProfiledThread();
+
+  const RunningTimes newRunningTimes = GetRunningTimesWithTightTimestamp(
+      [profiledThread](RunningTimes& aRunningTimes) {
+        AUTO_PROFILER_STATS(GetRunningTimes_QueryThreadCycleTime);
+        if (ULONG64 cycles;
+            QueryThreadCycleTime(profiledThread, &cycles) != 0) {
+          aRunningTimes.ResetThreadCPUDelta(cycles);
+        } else {
+          aRunningTimes.ClearThreadCPUDelta();
+        }
+      });
+
+  const RunningTimes diff =
+      newRunningTimes - platformData->PreviousThreadRunningTimesRef();
+  platformData->PreviousThreadRunningTimesRef() = newRunningTimes;
+  return diff;
+}
+
+template <typename Func>
+void Sampler::SuspendAndSampleAndResumeThread(
+    PSLockRef aLock, const RegisteredThread& aRegisteredThread,
+    const TimeStamp& aNow, const Func& aProcessRegs) {
+  HANDLE profiled_thread =
+      aRegisteredThread.GetPlatformData()->ProfiledThread();
+  if (profiled_thread == nullptr) {
+    return;
+  }
+
+  // Context used for sampling the register state of the profiled thread.
+  CONTEXT context;
+  memset(&context, 0, sizeof(context));
+
+  //----------------------------------------------------------------//
+  // Suspend the samplee thread and get its context.
+
+  static const DWORD kSuspendFailed = static_cast<DWORD>(-1);
+  if (SuspendThread(profiled_thread) == kSuspendFailed) {
+    return;
+  }
+
+  // SuspendThread is asynchronous, so the thread may still be running.
+  // Call GetThreadContext first to ensure the thread is really suspended.
+  // See https://blogs.msdn.microsoft.com/oldnewthing/20150205-00/?p=44743.
+
+  // Using only CONTEXT_CONTROL is faster but on 64-bit it causes crashes in
+  // RtlVirtualUnwind (see bug 1120126) so we set all the flags.
+#if defined(GP_ARCH_amd64)
+  context.ContextFlags = CONTEXT_FULL;
+#else
+  context.ContextFlags = CONTEXT_CONTROL;
+#endif
+  if (!GetThreadContext(profiled_thread, &context)) {
+    ResumeThread(profiled_thread);
+    return;
+  }
+
+  //----------------------------------------------------------------//
+  // Sample the target thread.
+
+  // WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
+  //
+  // The profiler's "critical section" begins here.  We must be very careful
+  // what we do here, or risk deadlock.  See the corresponding comment in
+  // platform-linux-android.cpp for details.
+
+  Registers regs;
+  PopulateRegsFromContext(regs, &context);
+  aProcessRegs(regs, aNow);
+
+  //----------------------------------------------------------------//
+  // Resume the target thread.
+
+  ResumeThread(profiled_thread);
+
+  // The profiler's critical section ends here.
+  //
+  // WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
+}
+
+// END Sampler target specifics
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+// BEGIN SamplerThread target specifics
+
+static unsigned int __stdcall ThreadEntry(void* aArg) {
+  auto thread = static_cast<SamplerThread*>(aArg);
+  thread->Run();
+  return 0;
+}
+
+SamplerThread::SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
+                             double aIntervalMilliseconds)
+    : mSampler(aLock),
+      mActivityGeneration(aActivityGeneration),
+      mIntervalMicroseconds(
+          std::max(1, int(floor(aIntervalMilliseconds * 1000 + 0.5)))) {
+  // By default we'll not adjust the timer resolution which tends to be
+  // around 16ms. However, if the requested interval is sufficiently low
+  // we'll try to adjust the resolution to match.
+  if (mIntervalMicroseconds < 10 * 1000) {
+    ::timeBeginPeriod(mIntervalMicroseconds / 1000);
+  }
+
+  // Create a new thread. It is important to use _beginthreadex() instead of
+  // the Win32 function CreateThread(), because the CreateThread() does not
+  // initialize thread-specific structures in the C runtime library.
+  mThread = reinterpret_cast<HANDLE>(_beginthreadex(nullptr,
+                                                    /* stack_size */ 0,
+                                                    ThreadEntry, this,
+                                                    /* initflag */ 0, nullptr));
+  if (mThread == 0) {
+    MOZ_CRASH("_beginthreadex failed");
+  }
+}
+
+SamplerThread::~SamplerThread() {
+  WaitForSingleObject(mThread, INFINITE);
+
+  // Close our own handle for the thread.
+  if (mThread != kNoThread) {
+    CloseHandle(mThread);
+  }
+
+  // Just in the unlikely case some callbacks were added between the end of the
+  // thread and now.
+  InvokePostSamplingCallbacks(std::move(mPostSamplingCallbackList),
+                              SamplingState::JustStopped);
+}
+
+void SamplerThread::SleepMicro(uint32_t aMicroseconds) {
+  // For now, keep the old behaviour of minimum Sleep(1), even for
+  // smaller-than-usual sleeps after an overshoot, unless the user has
+  // explicitly opted into a sub-millisecond profiler interval.
+  if (mIntervalMicroseconds >= 1000) {
+    ::Sleep(std::max(1u, aMicroseconds / 1000));
+  } else {
+    TimeStamp start = TimeStamp::NowUnfuzzed();
+    TimeStamp end = start + TimeDuration::FromMicroseconds(aMicroseconds);
+
+    // First, sleep for as many whole milliseconds as possible.
+    if (aMicroseconds >= 1000) {
+      ::Sleep(aMicroseconds / 1000);
+    }
+
+    // Then, spin until enough time has passed.
+    while (TimeStamp::NowUnfuzzed() < end) {
+      YieldProcessor();
+    }
+  }
+}
+
+void SamplerThread::Stop(PSLockRef aLock) {
+  // Disable any timer resolution changes we've made. Do it now while
+  // gPSMutex is locked, i.e. before any other SamplerThread can be created
+  // and call ::timeBeginPeriod().
+  //
+  // It's safe to do this now even though this SamplerThread is still alive,
+  // because the next time the main loop of Run() iterates it won't get past
+  // the mActivityGeneration check, and so it won't make any more ::Sleep()
+  // calls.
+  if (mIntervalMicroseconds < 10 * 1000) {
+    ::timeEndPeriod(mIntervalMicroseconds / 1000);
+  }
+
+  mSampler.Disable(aLock);
+}
+
+// END SamplerThread target specifics
+////////////////////////////////////////////////////////////////////////
+
+static void PlatformInit(PSLockRef aLock) {}
+
+#if defined(HAVE_NATIVE_UNWIND)
+void Registers::SyncPopulate() {
+  CONTEXT context;
+  RtlCaptureContext(&context);
+  PopulateRegsFromContext(*this, &context);
+}
+#endif
+
+#if defined(GP_PLAT_amd64_windows)
+
+// Use InitializeWin64ProfilerHooks from the base profiler.
+
+namespace mozilla {
+namespace baseprofiler {
+MFBT_API void InitializeWin64ProfilerHooks();
+}  // namespace baseprofiler
+}  // namespace mozilla
+
+using mozilla::baseprofiler::InitializeWin64ProfilerHooks;
+
+#endif  // defined(GP_PLAT_amd64_windows)