Enable concurrent sweep on MIPS and ARM64.

runtime/vm/assembler_mips_test.cc

 // Copyright (c) 2013, 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 "vm/globals.h"
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/os.h"
@@ skipping 2151 matching lines @@
             RANGE_OF(Integer::New(static_cast<int64_t>(kMinInt32) - 1)));
   EXPECT_EQ(ICData::kInt64RangeBit, RANGE_OF(Integer::New(kMaxInt64)));
   EXPECT_EQ(ICData::kInt64RangeBit, RANGE_OF(Integer::New(kMinInt64)));
 
   EXPECT_EQ(-1, RANGE_OF(Bool::True().raw()));
 
 #undef RANGE_OF
 }
 
 
+ASSEMBLER_TEST_GENERATE(Semaphore, assembler) {
+  __ EnterFrame();
+  __ LoadImmediate(T0, 40);
+  __ LoadImmediate(T1, 42);
+  __ Push(T0);
+  Label retry;
+  __ Bind(&retry);
+  __ ll(T0, Address(SP));
+  __ mov(T2, T1);
+  __ sc(T2, Address(SP));  // T1 == 1, success
+  __ LoadImmediate(T3, 1);
+  __ bne(T2, T3, &retry);  // NE if context switch occurred between ll and sc
+  __ Pop(V0);  // 42
+  __ LeaveFrameAndReturn();
+}
+
+
+ASSEMBLER_TEST_RUN(Semaphore, test) {
+  EXPECT(test != NULL);
+  typedef int (*Semaphore)() DART_UNUSED;
+  EXPECT_EQ(42, EXECUTE_TEST_CODE_INT32(Semaphore, test->entry()));
+}
+
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS