From 523e9495fc763e5924ad6e0b140ae88e0e4afe9b Mon Sep 17 00:00:00 2001
From: Pavel Kunyavskiy <pavel.kunyavskiy@jetbrains.com>
Date: Tue, 17 Aug 2021 10:08:40 +0300
Subject: [PATCH] [K/N] Optimize safepoint implementation

---
 .../gc/stms/cpp/SameThreadMarkAndSweep.cpp    | 21 ++++++++++++-------
 .../gc/stms/cpp/SameThreadMarkAndSweep.hpp    |  1 +
 .../runtime/src/mm/cpp/ThreadSuspension.cpp   | 17 +++++++++------
 .../runtime/src/mm/cpp/ThreadSuspension.hpp   |  1 +
 4 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/kotlin-native/runtime/src/gc/stms/cpp/SameThreadMarkAndSweep.cpp b/kotlin-native/runtime/src/gc/stms/cpp/SameThreadMarkAndSweep.cpp
index 52162c236b2..5e32a10944d 100644
--- a/kotlin-native/runtime/src/gc/stms/cpp/SameThreadMarkAndSweep.cpp
+++ b/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 {
diff --git a/kotlin-native/runtime/src/gc/stms/cpp/SameThreadMarkAndSweep.hpp b/kotlin-native/runtime/src/gc/stms/cpp/SameThreadMarkAndSweep.hpp
index 7af6898523d..f8f83b40770 100644
--- a/kotlin-native/runtime/src/gc/stms/cpp/SameThreadMarkAndSweep.hpp
+++ b/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_;
diff --git a/kotlin-native/runtime/src/mm/cpp/ThreadSuspension.cpp b/kotlin-native/runtime/src/mm/cpp/ThreadSuspension.cpp
index 1d3cc90c266..e3ef95ca275 100644
--- a/kotlin-native/runtime/src/mm/cpp/ThreadSuspension.cpp
+++ b/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;
 }
diff --git a/kotlin-native/runtime/src/mm/cpp/ThreadSuspension.hpp b/kotlin-native/runtime/src/mm/cpp/ThreadSuspension.hpp
index f55018e77f8..f2c52e6832c 100644
--- a/kotlin-native/runtime/src/mm/cpp/ThreadSuspension.hpp
+++ b/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;