Remove unneeded zeroing TLS (#4480)

kotlin-native/backend.native/tests/build.gradle

@@ -1044,6 +1044,12 @@ task worker11(type: KonanLocalTest) {
     source = "runtime/workers/worker11.kt"
 }
 
+standaloneTest("worker_threadlocal_no_leak") {
+    disabled = project.globalTestArgs.contains('-opt') || (project.testTarget == 'wasm32') // Needs debug build and pthreads.
+    source = "runtime/workers/worker_threadlocal_no_leak.kt"
+    flags = ['-g']
+}
+
 task freeze0(type: KonanLocalTest) {
     enabled = (project.testTarget != 'wasm32') // No workers on WASM.
     goldValue = "frozen bit is true\n" +

kotlin-native/backend.native/tests/runtime/workers/worker_threadlocal_no_leak.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+import kotlin.native.concurrent.*
+
+@ThreadLocal
+var x = Any()
+
+fun main() {
+    val worker = Worker.start()
+
+    worker.execute(TransferMode.SAFE, {}) {
+        println(x)  // Make sure x is initialized
+    }.result
+
+    worker.requestTermination().result
+}

kotlin-native/runtime/src/main/cpp/Runtime.cpp

@@ -224,11 +224,6 @@ KBoolean Konan_Platform_isDebugBinary() {
   return KonanNeedDebugInfo ? true : false;
 }
 
-void Kotlin_zeroOutTLSGlobals() {
-  if (runtimeState != nullptr && runtimeState->memoryState != nullptr)
-    InitOrDeinitGlobalVariables(DEINIT_THREAD_LOCAL_GLOBALS, runtimeState->memoryState);
-}
-
 bool Kotlin_memoryLeakCheckerEnabled() {
   return g_checkLeaks;
 }

kotlin-native/runtime/src/main/cpp/Runtime.h

@@ -31,9 +31,6 @@ void Kotlin_deinitRuntimeIfNeeded();
 // Appends given node to an initializer list.
 void AppendToInitializersTail(struct InitNode*);
 
-// Zero out all Kotlin thread local globals.
-void Kotlin_zeroOutTLSGlobals();
-
 bool Kotlin_memoryLeakCheckerEnabled();
 
 bool Kotlin_cleanersLeakCheckerEnabled();

kotlin-native/runtime/src/main/cpp/Worker.cpp

@@ -815,10 +815,6 @@ void* workerRoutine(void* argument) {
     if (worker->processQueueElement(true) == JOB_TERMINATE) break;
   } while (true);
 
-  // Runtime deinit callback could be called when TLS is already zeroed out, so clear memory
-  // here explicitly. to make sure leak detector properly works.
-  Kotlin_zeroOutTLSGlobals();
-
   return nullptr;
 }