CTFE Status

[Stefan Koch via Digitalmars-d]

On Wednesday, 16 November 2016 at 09:45:24 UTC, Stefan Koch wrote:
> Here is a small demostration of the performance increase :
>
> [root at localhost dmd]# time src/dmd -c testSettingArrayLength.d
> > x 2> x
>
> real	0m0.199s
> user	0m0.180s
> sys	0m0.017s
> [root at localhost dmd]# time src/dmd -c testSettingArrayLength.d 
> -bc-ctfe > x 2> x
>
> real	0m0.072s
> user	0m0.050s
> sys	0m0.020s
>
> Please note that newCTFE only spends 15 ms inside the 
> evaluation, most time is spent clearing the 2^^24 Bytes of 
> heap-memory to zero.
>
> The sourcode of testSettingArrayLength is
> uint[] MakeAndInitArr(uint length)
> {
>     uint[] arr;
>     arr.length = length;
>
>     foreach(i;0 .. length)
>     {
>         arr[i] = i + 3;
>     }
>     return arr;
> }
>
> static assert(MakeAndInitArr(ushort.max).length == ushort.max);

A more accurate breakdown :

Initializing Heap:     18.6 ms
Generating Bytecode:    1.2 ms
Executing Bytecode:    13.2 ms
Converting to CTFE-EXp: 9.1 ms

For a second execution of the same function with the same 
arguments within the same file the numbers look like :

Initializing Heap:     16.7 ms
Generating Bytecode:    0.6 ms
Executing Bytecode:    13.2 ms
Converting to CTFE-EXp: 9.3 ms