Upgrade AlignedMemory to support dynamic allocations.

base/memory/aligned_memory.h

Index: base/memory/aligned_memory.h
diff --git a/base/memory/aligned_memory.h b/base/memory/aligned_memory.h
index 0a176347a6dd47768c20c9585870fcd9cef417f1..201337a6cba34f1233e6a2f691b0205c58807151 100644
--- a/base/memory/aligned_memory.h
+++ b/base/memory/aligned_memory.h
@@ -18,13 +18,31 @@
 //
 //   // ... later, to destruct my_class:
 //   my_class.data_as<MyClass>()->MyClass::~MyClass();
+//
+// Alternatively, a runtime sized aligned allocation can be created:
+//
+//   float* my_array = reinterpret_cast<float*>(AlignedAlloc(size, alignment));
+//
+//   // ... later, to release the memory:
+//   AlignedFree(my_array);
+//
+// Or using scoped_ptr_malloc:
+//
+//   scoped_ptr_malloc<float, ScopedPtrAlignedFree> my_array(
+//       reinterpret_cast<float*>(AlignedAlloc(size, alignment)));

[Jeffrey Yasskin, 2012/07/23 18:34:40]

These reinterpret_casts only need to be static_casts because they're void*->T*,
and _should_ be static_casts to make it clearer that every use of
reinterpret_cast<T*> is a potential bug.

[DaleCurtis, 2012/07/23 19:04:27]

Fixed all over.

 
 #ifndef BASE_MEMORY_ALIGNED_MEMORY_H_
 #define BASE_MEMORY_ALIGNED_MEMORY_H_
 
+#if defined(COMPILER_MSVC)

[willchan no longer on Chromium, 2012/07/23 18:48:45]

Platform specific #includes should be behind the cross-platform #includes, as
per Chromium style guide, unless you have a special need for these to be first
(AFAICT, not true).

[DaleCurtis, 2012/07/23 19:04:27]

Done. Causes a lint error though.

+#include <malloc.h>
+#else
+#include <stdlib.h>
+#endif
+
+#include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
-#include "base/logging.h"
 
 namespace base {
 
@@ -37,7 +55,6 @@ struct AlignedMemory {};
     template <size_t Size> \
     class AlignedMemory<Size, byte_alignment> { \
      public: \
-      ALIGNAS(byte_alignment) uint8 data_[Size]; \
       void* void_data() { return reinterpret_cast<void*>(data_); } \
       const void* void_data() const { \
         return reinterpret_cast<const void*>(data_); \
@@ -49,6 +66,7 @@ struct AlignedMemory {};
         return reinterpret_cast<const Type*>(void_data()); \
       } \
      private: \
+      ALIGNAS(byte_alignment) uint8 data_[Size]; \
       void* operator new(size_t); \
       void operator delete(void*); \
     }
@@ -71,6 +89,26 @@ BASE_DECL_ALIGNED_MEMORY(1024);
 BASE_DECL_ALIGNED_MEMORY(2048);
 BASE_DECL_ALIGNED_MEMORY(4096);
 
-}  // base
+#undef BASE_DECL_ALIGNED_MEMORY
+
+BASE_EXPORT void* AlignedAlloc(size_t size, size_t alignment);
+
+inline void AlignedFree(void* ptr) {
+#if defined(COMPILER_MSVC)
+  _aligned_free(ptr);
+#else
+  free(ptr);
+#endif
+}
+
+// Helper class for use with scoped_ptr_malloc.
+class BASE_EXPORT ScopedPtrAlignedFree {
+ public:
+  inline void operator()(void* x) const {
+    AlignedFree(x);
+  }
+};
+
+}  // namespace base
 
 #endif  // BASE_MEMORY_ALIGNED_MEMORY_H_