Upgrade AlignedMemory to support dynamic allocations.

base/memory/aligned_memory.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/memory/aligned_memory.h"
+
+#include "base/logging.h"
+
+#if defined(OS_ANDROID) || defined(OS_NACL)
+#include <malloc.h>
+#endif
+
+namespace base {
+
+void* AlignedAlloc(size_t size, size_t alignment) {
+  DCHECK_GT(size, 0U);
+  DCHECK_EQ(alignment & (alignment - 1), 0U);
+  DCHECK_EQ(alignment % sizeof(void*), 0U);
+  void* ptr = NULL;
+#if defined(COMPILER_MSVC)
+  ptr = _aligned_malloc(size, alignment);
+// Both Android and NaCl technically support posix_memalign(), but do not expose
+// it in the current version of the library headers used by Chrome.  Luckily,
+// memalign() on both platforms returns pointers which can safely be used with
+// free(), so we can use it instead.
+#elif defined(OS_ANDROID) || defined(OS_NACL)
+  ptr = memalign(alignment, size);
+#else
+  if (posix_memalign(&ptr, alignment, size))
+    ptr = NULL;
+#endif
+  // Since aligned allocations may fail for non-memory related reasons, force a
+  // crash if we encounter a failed allocation; maintaining consistent behavior
+  // with a normal allocation failure in Chrome.
+  if (!ptr) {
+    // Instead of CHECK(ptr) << msg, avoid binary bloat by moving msg into DLOG.

[willchan no longer on Chromium, 2012/07/23 20:37:18]

No need for this comment. It's just a general principle that should be followed
(I don't think we want this type of comment for every DLOG, just keep educating
people and updating online docs).

[DaleCurtis, 2012/07/23 21:15:04]

Done.

+    DLOG(ERROR) << "If you crashed here, your aligned allocation is incorrect: "
+        << "size=" << size << ", alignment=" << alignment;

[willchan no longer on Chromium, 2012/07/23 20:37:18]

<< should line up with previous line, as per Google style guide.

[DaleCurtis, 2012/07/23 21:15:04]

Done.

+    CHECK(false);
+  }
+  // Sanity check alignment just to be safe.
+  DCHECK_EQ(reinterpret_cast<uintptr_t>(ptr) & (alignment - 1), 0U);
+  return ptr;
+}
+
+}  // namespace base