Add VerifiedMemory helper for write-barrier verification.

runtime/vm/verified_memory_test.cc

Index: runtime/vm/verified_memory_test.cc
===================================================================
--- runtime/vm/verified_memory_test.cc	(revision 0)
+++ runtime/vm/verified_memory_test.cc	(revision 0)
@@ -0,0 +1,85 @@
+// Copyright (c) 2014, 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/verified_memory.h"
+
+namespace dart {
+
+void Init() {
+#if defined(DEBUG)
+  FLAG_verified_mem = true;
+#endif
+}
+
+
+UNIT_TEST_CASE(VerifiedMemoryBasic) {
+  Init();
+  const intptr_t kReservationSize = 64 * KB;
+  VirtualMemory* vm = VerifiedMemory::Reserve(kReservationSize);
+  EXPECT_EQ(kReservationSize, vm->size());
+  vm->Commit(false);
+  double* addr = reinterpret_cast<double*>(vm->address());
+  VerifiedMemory::Write(&addr[0], 0.5);
+  EXPECT_EQ(0.5, addr[0]);
+  VerifiedMemory::Write(&addr[1], 1.5);
+  VerifiedMemory::Write(&addr[2], 2.5);
+  VerifiedMemory::Write(&addr[0], 0.25);
+  static const double kNaN = NAN;
+  VerifiedMemory::Write(&addr[0], kNaN);  // Bitwise comparison should be used.
+  VerifiedMemory::Write(&addr[0], 0.5);
+  int64_t* unverified = reinterpret_cast<int64_t*>(&addr[3]);
+  *unverified = 123;
+  VerifiedMemory::Verify(reinterpret_cast<uword>(addr), 3 * sizeof(double));
+}
+
+
+UNIT_TEST_CASE(VerifiedMemoryAccept) {
+  Init();
+  const intptr_t kReservationSize = 64 * KB;
+  VirtualMemory* vm = VerifiedMemory::Reserve(kReservationSize);
+  EXPECT_EQ(kReservationSize, vm->size());
+  vm->Commit(false);
+  double* addr = reinterpret_cast<double*>(vm->address());
+  VerifiedMemory::Write(&addr[0], 0.5);
+  VerifiedMemory::Write(&addr[1], 1.5);
+  VerifiedMemory::Write(&addr[2], 2.5);
+  VerifiedMemory::Write(&addr[0], 0.25);
+  // Unverified write followed by Accept ("I know what I'm doing").
+  memset(addr, 0xf3, 2 * sizeof(double));
+  VerifiedMemory::Accept(reinterpret_cast<uword>(addr), 2 * sizeof(double));
+  VerifiedMemory::Verify(reinterpret_cast<uword>(addr), 3 * sizeof(double));
+}
+
+
+// Negative tests below.
+
+UNIT_TEST_CASE(VerifyImplicit_Crash) {
+  Init();
+  const intptr_t kReservationSize = 64 * KB;
+  VirtualMemory* vm = VerifiedMemory::Reserve(kReservationSize);
+  EXPECT_EQ(kReservationSize, vm->size());
+  vm->Commit(false);
+  double* addr = reinterpret_cast<double*>(vm->address());
+  addr[0] = 0.5;  // Forget to use Write.
+  VerifiedMemory::Write(&addr[0], 1.5);
+}
+
+
+UNIT_TEST_CASE(VerifyExplicit_Crash) {
+  Init();
+  const intptr_t kReservationSize = 64 * KB;
+  VirtualMemory* vm = VerifiedMemory::Reserve(kReservationSize);
+  EXPECT_EQ(kReservationSize, vm->size());
+  vm->Commit(false);
+  double* addr = reinterpret_cast<double*>(vm->address());
+  VerifiedMemory::Write(&addr[0], 0.5);
+  VerifiedMemory::Write(&addr[1], 1.5);
+  addr[1] = 3.5;  // Forget to use Write.
+  VerifiedMemory::Write(&addr[2], 2.5);
+  VerifiedMemory::Verify(reinterpret_cast<uword>(addr), 3 * sizeof(double));
+}
+
+}  // namespace dart