Discussion Thread: DIP 1036--String Interpolation Tuple Literals--Community Review Round 2

Adam D. Ruppe destructionator at gmail.com
Tue Feb 2 13:53:18 UTC 2021

On Tuesday, 2 February 2021 at 13:06:06 UTC, Andrei Alexandrescu 
> Thought: std.bitmanip.bitfields has some gnarly code that 
> generates shifting and masking code for bitfields. It would be 
> great to show how that code is vastly improved by the DIP.

Indeed, yikes.

And all that CTFE ~ work... ctfe performs very poorly with ~. So 
it would be worth making the interpolation function (idup or 
whatever we call it) be sure to avoid that. Doing array copies 
into preallocated buffers (buffer[spot .. spot + what.length] = 
what[], spot += what.length) is *significantly* faster, you can 
double or triple the speed of builds and cut dmd memory use down 
by 10x with those simple changes if you use the concated mixins 
heavily (my little jni.d did it like this at first and I did 
realize such enormous gains there, it was incredible).

That's fairly easy to do with the dip too since 1) the string 
literal pieces themselves are all known at compile time and 2) 
the length and types of the argument tuple is also known ahead of 
time, so you can use a static array to cache their intermediates 
(as necessary) while gathering their runtime lengths for the 
final copy.

If I can find some time later today I'll see what I can do with 

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