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Comment by groby_b | Hacker News Reader

That does not hold for Intel x86 architecture chips, which are perfectly happy to have unaligned integers.

As for struct members, the alignment is (of course) "implementation defined", which is the fancy way of throwing up your hands and saying "whatever". (Since C++11 we actually have alignas(), which at least gives manual control)

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Many (most? all?) allocators are guaranteed to give you back aligned pointers.

For instance, jemalloc(3) on amd64 platforms will give back 16-byte aligned pointers:

  [...] The allocated space is suitably aligned
  (after possible pointer coercion) for storage of any type of object.

One can construct an aligned pointer on a chunk of allocated memory by asking for the needed quantity plus the size of the alignment and the "nudge" the pointer you get to the next word boundary (and you can do something with the "wasted" byte before it, like storing the size of the object).

But that sort of trick is only worth it if you are writing a compiler and its runtime, an interpreter, a memory allocator (in particular GCs) or at the very last some sort of high performance library (you would return your "featured pointer" as an opaque type to the user).

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