Add unit test for freeing VirtualMemory.

runtime/vm/virtual_memory_test.cc

 // Copyright (c) 2012, 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 "vm/unit_test.h"
 #include "vm/virtual_memory.h"
 
 namespace dart {
 
@@ skipping 21 matching lines @@
   buf[1] = 'c';
   buf[2] = '/';
   buf[3] = 'd';
   buf[4] = 'c';
   buf[5] = 0;
   EXPECT_STREQ("ac/dc", buf);
 
   delete vm;
 }
 
+
+UNIT_TEST_CASE(FreeVirtualMemory) {
+  // Reservations should always be handed back to OS upon destruction.
+  const intptr_t kVirtualMemoryBlockSize = 10 * MB;
+  const intptr_t kIterations = 900;  // Enough to exhaust 32-bit address space.
+  for (intptr_t i = 0; i < kIterations; ++i) {
+    VirtualMemory* vm = VirtualMemory::Reserve(kVirtualMemoryBlockSize);
+    vm->Commit(false);

[Ivan Posva, 2014/10/09 18:31:56]

You might want to alternate the value for the executable flag, just to ensure it
has not impact.

+    delete vm;
+  }
+  // Check that truncation does not introduce leaks.
+  for (intptr_t i = 0; i < kIterations; ++i) {
+    VirtualMemory* vm = VirtualMemory::Reserve(kVirtualMemoryBlockSize);
+    vm->Commit(false);
+    vm->Truncate(kVirtualMemoryBlockSize / 2, true);
+    delete vm;
+  }
+  for (intptr_t i = 0; i < kIterations; ++i) {
+    VirtualMemory* vm = VirtualMemory::Reserve(kVirtualMemoryBlockSize);
+    vm->Commit(false);
+    vm->Truncate(kVirtualMemoryBlockSize / 2, false);
+    delete vm;
+  }
+  for (intptr_t i = 0; i < kIterations; ++i) {
+    VirtualMemory* vm = VirtualMemory::Reserve(kVirtualMemoryBlockSize);
+    vm->Commit(false);
+    vm->Truncate(0, true);
+    delete vm;
+  }
+  for (intptr_t i = 0; i < kIterations; ++i) {
+    VirtualMemory* vm = VirtualMemory::Reserve(kVirtualMemoryBlockSize);
+    vm->Commit(false);
+    vm->Truncate(0, false);
+    delete vm;
+  }
+}
+
 }  // namespace dart