1 files changed, 52 insertions, 0 deletions
diff --git a/mozglue/baseprofiler/core/ProfilingStack.cpp b/mozglue/baseprofiler/core/ProfilingStack.cpp
new file mode 100644
index 0000000000..f5cd2ddd04
--- /dev/null
+++ b/mozglue/baseprofiler/core/ProfilingStack.cpp
@@ -0,0 +1,52 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "BaseProfilingStack.h"
+
+#include <algorithm>
+
+#include "mozilla/IntegerRange.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/UniquePtrExtensions.h"
+
+#include "BaseProfiler.h"
+
+namespace mozilla {
+namespace baseprofiler {
+
+ProfilingStack::~ProfilingStack() {
+  // The label macros keep a reference to the ProfilingStack to avoid a TLS
+  // access. If these are somehow not all cleared we will get a
+  // use-after-free so better to crash now.
+  MOZ_RELEASE_ASSERT(stackPointer == 0);
+
+  delete[] frames;
+}
+
+void ProfilingStack::ensureCapacitySlow() {
+  MOZ_ASSERT(stackPointer >= capacity);
+  const uint32_t kInitialCapacity = 128;
+
+  uint32_t sp = stackPointer;
+  auto newCapacity =
+      std::max(sp + 1, capacity ? capacity * 2 : kInitialCapacity);
+
+  auto* newFrames = new ProfilingStackFrame[newCapacity];
+
+  // It's important that `frames` / `capacity` / `stackPointer` remain
+  // consistent here at all times.
+  for (auto i : IntegerRange(capacity)) {
+    newFrames[i] = frames[i];
+  }
+
+  ProfilingStackFrame* oldFrames = frames;
+  frames = newFrames;
+  capacity = newCapacity;
+  delete[] oldFrames;
+}
+
+}  // namespace baseprofiler
+}  // namespace mozilla