From Reddit

[Frits van Bommel]

bearophile wrote:
> Frits van Bommel:
> 
>> [LDC] [1]: It currently does not realize the array load can be done before the function call, but I submitted a patch to LLVM for that. (This is why it currently needs to be split up, so that LDC emits the load before the function call)<
> 
> I guess you mean this:
> http://llvm.org/bugs/show_bug.cgi?id=4323

Yes, but the mailing list post in the last comment has the latest version of the 
patch attached. (removing a prerequisite change that has already been applied, 
and fixing one of the tests which was too imprecise)

> It seems they are accepting such changes of yours, you are good :-)

Getting patches in isn't all that hard as long as they're not buggy and change 
something for the better :).

Keeping them small helps too, since it makes for easier (and quicker) reviews.

>> Note that if the accumulator is introduced manually, the tail recursion indeed gets eliminated by DMD (and turned into a loop).<
> 
> Very good, thank you for modifying the code.

No problem.