FYI - mo' work on std.allocator

[Steven Schveighoffer via Digitalmars-d]

On Sun, 27 Apr 2014 01:43:08 -0400, Andrei Alexandrescu  
<SeeWebsiteForEmail at erdani.org> wrote:

> Added SbrkRegion, SimpleBlocklist, and Blocklist.
>
> http://erdani.com/d/phobos-prerelease/std_allocator.html#.SbrkRegion
> http://erdani.com/d/phobos-prerelease/std_allocator.html#.SimpleBlocklist
> http://erdani.com/d/phobos-prerelease/std_allocator.html#.Blocklist
>
> https://github.com/andralex/phobos/blob/allocator/std/allocator.d
>
> Destruction is as always welcome. I plan to get into tracing tomorrow  
> morning.

First time I've seen it, so I'm looking at everything.

In the design docs:

alignedAllocate(size_t s, uint a);, $(RES) is null ||
$(RES).length == s) $(TD Similar to $(D allocate), with the additional  
guarantee
that the memory returned is aligned to at least $(D a) bytes. $(D a) must  
be a
power of 2 greater than $(D (void*).sizeof).))

Why power of 2 greater than void*.sizeof? Seems like an extra check that  
isn't necessary.

Consider that any block that is aligned to a power of 2 called N, it's  
also aligned by any power of 2 < N. I think specifying any power of 2 is  
fine (including 1!). If anything, a maximum power of 2 may be good,  
because that's not as easy to ensure.

-Steve