Upgrade AlignedMemory to support dynamic allocations.

base/compiler_specific.h

Index: base/compiler_specific.h
diff --git a/base/compiler_specific.h b/base/compiler_specific.h
index 64273a98db93c4fc0158690958bc7cd4de225d32..342f3ea8b2f7e338bc9a7973c0eae948e45b7930 100644
--- a/base/compiler_specific.h
+++ b/base/compiler_specific.h
@@ -114,11 +114,13 @@
 #define ALIGNAS(byte_alignment) __attribute__((aligned(byte_alignment)))
 #endif
 
-// Return the byte alignment of the given type (available at compile time).
+// Return the byte alignment of the given type (available at compile time).  Use
+// sizeof(type) prior to checking __alignof to workaround Visual C++ bug:
+// http://goo.gl/isH0C

[scherkus (not reviewing), 2012/07/19 21:49:39]

FYI it's ok to exceed 80 chars for long urls

[DaleCurtis, 2012/07/20 02:38:56]

Yeah, this one is 131 chars though, so it seemed nicer to shorten it.

 // Use like:
 //   ALIGNOF(int32)  // this would be 4
 #if defined(COMPILER_MSVC)
-#define ALIGNOF(type) __alignof(type)
+#define ALIGNOF(type) (sizeof(type) - sizeof(type)) + __alignof(type)

[jbates, 2012/07/19 03:45:37]

parens should probably go around the whole expression.

[DaleCurtis, 2012/07/20 02:38:56]

Done.

 #elif defined(COMPILER_GCC)
 #define ALIGNOF(type) __alignof__(type)
 #endif