[K/N] Optimize safepoint implementation

kotlin-native/runtime/src/gc/stms/cpp/SameThreadMarkAndSweep.cpp

@@ -99,16 +99,23 @@ void gc::SameThreadMarkAndSweep::ThreadData::OnOOM(size_t size) noexcept {
     PerformFullGC();
 }
 
-void gc::SameThreadMarkAndSweep::ThreadData::SafePointRegular(size_t weight) noexcept {
-    size_t counterOverhead = gc_.GetThreshold() == 0 ? safePointsCounter_ : safePointsCounter_ % gc_.GetThreshold();
-    if (threadData_.suspensionData().suspendIfRequested()) {
-        safePointsCounter_ = 0;
-    } else if (counterOverhead + weight >= gc_.GetThreshold() && konan::getTimeMicros() - timeOfLastGcUs_ >= gc_.GetCooldownThresholdUs()) {
+void gc::SameThreadMarkAndSweep::ThreadData::SafePointRegularSlowPath() noexcept {
+    safePointsCounter_ = 0;
+    if (konan::getTimeMicros() - timeOfLastGcUs_ >= gc_.GetCooldownThresholdUs()) {
         timeOfLastGcUs_ = konan::getTimeMicros();
-        safePointsCounter_ = 0;
         PerformFullGC();
     }
-    safePointsCounter_ += weight;
+}
+
+void gc::SameThreadMarkAndSweep::ThreadData::SafePointRegular(size_t weight) noexcept {
+    if (threadData_.suspensionData().suspendIfRequested()) {
+        safePointsCounter_ = 0;
+    } else {
+        safePointsCounter_ += weight;
+        if (safePointsCounter_ >= gc_.GetThreshold()) {
+            SafePointRegularSlowPath();
+        }
+    }
 }
 
 gc::SameThreadMarkAndSweep::SameThreadMarkAndSweep() noexcept {

kotlin-native/runtime/src/gc/stms/cpp/SameThreadMarkAndSweep.hpp

@@ -56,6 +56,7 @@ public:
 
     private:
         void SafePointRegular(size_t weight) noexcept;
+        void SafePointRegularSlowPath() noexcept;
 
         SameThreadMarkAndSweep& gc_;
         mm::ThreadData& threadData_;

kotlin-native/runtime/src/mm/cpp/ThreadSuspension.cpp

@@ -46,12 +46,17 @@ std::condition_variable gSuspendsionCondVar;
 
 NO_EXTERNAL_CALLS_CHECK bool kotlin::mm::ThreadSuspensionData::suspendIfRequested() noexcept {
     if (IsThreadSuspensionRequested()) {
-        std::unique_lock lock(gSuspensionMutex);
-        if (IsThreadSuspensionRequested()) {
-            AutoReset scopedAssign(&suspended_, true);
-            gSuspendsionCondVar.wait(lock, []() { return !IsThreadSuspensionRequested(); });
-            return true;
-        }
+        return suspendIfRequestedSlowPath();
+    }
+    return false;
+}
+
+NO_EXTERNAL_CALLS_CHECK bool kotlin::mm::ThreadSuspensionData::suspendIfRequestedSlowPath() noexcept {
+    std::unique_lock lock(gSuspensionMutex);
+    if (IsThreadSuspensionRequested()) {
+        AutoReset scopedAssign(&suspended_, true);
+        gSuspendsionCondVar.wait(lock, []() { return !IsThreadSuspensionRequested(); });
+        return true;
     }
     return false;
 }

kotlin-native/runtime/src/mm/cpp/ThreadSuspension.hpp

@@ -36,6 +36,7 @@ public:
 private:
     std::atomic<ThreadState> state_;
     std::atomic<bool> suspended_;
+    bool suspendIfRequestedSlowPath() noexcept;
 };
 
 bool IsThreadSuspensionRequested() noexcept;