1 files changed, 59 insertions, 0 deletions
diff --git a/hal/cocoa/CocoaHeterogeneousCpuInfo.cpp b/hal/cocoa/CocoaHeterogeneousCpuInfo.cpp
new file mode 100644
index 0000000000..065a25b930
--- /dev/null
+++ b/hal/cocoa/CocoaHeterogeneousCpuInfo.cpp
@@ -0,0 +1,59 @@
+/* -*- 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 https://mozilla.org/MPL/2.0/. */
+
+#include "Hal.h"
+#include "HalTypes.h"
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#include "mozilla/BitSet.h"
+
+namespace mozilla::hal_impl {
+
+mozilla::Maybe<hal::HeterogeneousCpuInfo> CreateHeterogeneousCpuInfo() {
+#ifdef __aarch64__
+  // As of now on Apple Silicon the number of *.logicalcpu_max is the same as
+  // *.physicalcpu_max.
+  size_t len = sizeof(uint32_t);
+  uint32_t pCores = 0;
+  if (sysctlbyname("hw.perflevel0.logicalcpu_max", &pCores, &len, nullptr, 0)) {
+    return Nothing();
+  }
+
+  len = sizeof(uint32_t);
+  uint32_t eCores = 0;
+  if (sysctlbyname("hw.perflevel1.logicalcpu_max", &eCores, &len, nullptr, 0)) {
+    return Nothing();
+  }
+
+  hal::HeterogeneousCpuInfo info;
+  info.mTotalNumCpus = pCores + eCores;
+
+  // The API has currently a limit how many cpu cores it can tell about.
+  for (uint32_t i = 0; i < hal::HeterogeneousCpuInfo::MAX_CPUS; ++i) {
+    if (pCores) {
+      --pCores;
+      info.mBigCpus[i] = true;
+    } else if (eCores) {
+      --eCores;
+      info.mLittleCpus[i] = true;
+    } else {
+      break;
+    }
+  }
+
+  return Some(info);
+#else
+  return Nothing();
+#endif
+}
+
+const Maybe<hal::HeterogeneousCpuInfo>& GetHeterogeneousCpuInfo() {
+  static const Maybe<hal::HeterogeneousCpuInfo> cpuInfo =
+      CreateHeterogeneousCpuInfo();
+  return cpuInfo;
+}
+
+}  // namespace mozilla::hal_impl