More zero-initialization optimizations pending in std.experimental.allocator?

[Per Nordlöw]

On Saturday, 20 October 2018 at 15:10:38 UTC, Nathan S. wrote:
>> are there more zero-initializations that can be optimized in 
>> std.experimental.allocator?
>
> I looked and identified low-hanging fruit in 
> std.mutation.initializeAll & moveEmplace and in 
> std.typecons.RefCounted (PR #6698), and in 
> std.conv.emplaceInitializer (PR #6461).

What did you search for to find these?

> Other opportunities would rely on being able to identify if 
> it's ever more efficient to write `memset(&x, 0, 
> typeof(x).sizeof)` instead of `x = typeof(x).init` which seems 
> like the kind of optimization that belongs in the compiler 
> instead.

So in which cases is `memset` faster than assignment?

Thanks!