Make NoReloadScope thread safe

runtime/vm/atomic_test.cc

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/atomic.h"
 #include "vm/globals.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
 UNIT_TEST_CASE(FetchAndIncrement) {
   uintptr_t v = 42;
   EXPECT_EQ(static_cast<uintptr_t>(42),
             AtomicOperations::FetchAndIncrement(&v));
   EXPECT_EQ(static_cast<uintptr_t>(43), v);
 }
 
 
 UNIT_TEST_CASE(FetchAndDecrement) {
   uintptr_t v = 42;
   EXPECT_EQ(static_cast<uintptr_t>(42),
             AtomicOperations::FetchAndDecrement(&v));
   EXPECT_EQ(static_cast<uintptr_t>(41), v);
 }
 
 
+UNIT_TEST_CASE(FetchAndIncrementSigned) {
+  intptr_t v = -42;
+  EXPECT_EQ(static_cast<intptr_t>(-42),
+            AtomicOperations::FetchAndIncrement(&v));
+  EXPECT_EQ(static_cast<intptr_t>(-41), v);
+}
+
+
+UNIT_TEST_CASE(FetchAndDecrementSigned) {
+  intptr_t v = -42;
+  EXPECT_EQ(static_cast<intptr_t>(-42),
+            AtomicOperations::FetchAndDecrement(&v));
+  EXPECT_EQ(static_cast<intptr_t>(-43), v);
+}
+
+
 UNIT_TEST_CASE(IncrementBy) {
   intptr_t v = 42;
   AtomicOperations::IncrementBy(&v, 100);
   EXPECT_EQ(static_cast<intptr_t>(142), v);
 }
 
 
 UNIT_TEST_CASE(DecrementBy) {
   intptr_t v = 42;
   AtomicOperations::DecrementBy(&v, 41);
@@ skipping 18 matching lines @@
 
 TEST_CASE(CompareAndSwapUint32) {
   uint32_t old_value = 42;
   uint32_t new_value = 100;
   uint32_t result = AtomicOperations::CompareAndSwapUint32(
       &old_value, old_value, new_value);
   EXPECT_EQ(static_cast<uint32_t>(42), result);
 }
 
 }  // namespace dart