Can you shrink it further?

[Stefan Koch via Digitalmars-d]

On Tuesday, 11 October 2016 at 08:03:40 UTC, Stefan Koch wrote:
> On Tuesday, 11 October 2016 at 07:30:26 UTC, Matthias Bentrup 
> wrote:
>>
>> A branch-free version:
>>
>> void popFront4(ref char[] s) @trusted pure nothrow {
>>   immutable c = s[0];
>>   uint char_length = 1 + (c >= 192) + (c >= 240) + (c >= 248);
>>   s = s.ptr[char_length .. s.length];
>> }
>>
>> Theoretically the char_length could be computed with three sub 
>> and addc instructions, but no compiler is smart enough to 
>> detect that.
>
> You still need to special case c < 128
> as well as the follow chars.
>
> also smaller c's are more common the bigger ones making the 
> branching version faster on average.

Also the code produces conditional set instructions which have a 
higher latency.
And worse throughput.