Official DMD compiler written in D

[Dmitry Olshansky]

11-Jan-2013 05:43, Timon Gehr пишет:
> On 01/10/2013 08:52 PM, Dmitry Olshansky wrote:
[snip]
>>
>> Cool! I'd love to take even the very preliminary peek at the speed
>> profile of this CTFE engine.
>>
>> If you are interested I'd love to test a small (the code though contains
>> a lot of static data) CTFE benchmark that is the bottleneck in the
>> compilation of current ctRegex.
>>
>> See the attachment here:
>> http://d.puremagic.com/issues/show_bug.cgi?id=7442
>>
>> would be nice to see some rough numbers for this vs DMD.
>>
>
> I'll let you know as soon as the example runs. Currently this is blocked
> by the missing implementation for the following language features:
>
> - import declarations
> - UFCS
> - Optional parens on function calls
> - Struct literals
> - Static struct data
> - debug declarations
> - Some of the built-in array operations
> - Missing object.d (no string, size_t, hash_t alias.)
> - (static) foreach
> - __ctfe
>

I guess that core.bitop intrinsics too. Either way, thanks in advance.

> I will prioritize those features. Except import declarations, they are
> mostly easy to implement, but I haven't gotten around to them yet.
>
> For the meantime, maybe these quick measurements are somewhat useful:
>

They truly are. As I've been long wondering that CTFE could be quite 
fast if it wasn't for it's current architecture in DMD. Just needed the 
hard data to go by.

> int[] erathos(int x){
>      bool[] p;
>      for(int i=0;i<=x;i++) p~=true;
>      for(int i=3;i*i<=x;i+=2){
>          if(p[i]) for(int k=i*i;k<=x;k=k+i) p[k]=false;
>      }
>      int[] r;
>      if(x>=2) r~=2;
>      for(int i=3;i<=x;i+=2) if(p[i]) r~=i;
>      return r;
> }
>
> pragma(msg, "erathos: ",erathos(40000).length);
>
>
> The frontend (32-bit dmd build, without -inline, otherwise DMD ICEs):
> $ time ./d erathos.d
> erathos: 4203U
>
> real    0m0.077s
> user    0m0.076s
> sys    0m0.000s
>
>
> DMD 2.060 (64 bit):
> $ time dmd -o- erathos.d
> erathos: 4203u
>
> real    0m2.594s
> user    0m0.716s
> sys    0m1.696s
>
>
> ...
>
> pragma(msg, "erathos: ",erathos(400000)); // (that is one 0 more)
>
> The frontend:
> erathos: 33860U
>
> real    0m0.662s
> user    0m0.660s
> sys    0m0.000s
>
> DMD: brings down the machine
>
> pragma(msg, "erathos: ",erathos(4000000)); // (yet another 0 more)
>
> The frontend:
> erathos: 283146U
>
> real    0m6.867s
> user    0m6.832s
> sys    0m0.016s
>
> // pragma(msg, "erathos: ",erathos(4000000));
> void main(){
>      import std.stdio;
>      writeln(erathos(4000000).length);
> }
>
> $ dmd -O -release -inline -noboundscheck erathos.d && time ./erathos
> dmd: module.c:829: void Module::semantic3(): Assertion `semanticstarted
> == 2' failed.

I bet this one was fixed in 2.061, I've recently seen the similar bug as 
resolved "works for me".

> (I'll see if it also fails with DMD 2.061.)
>
> $ dmd -O -release -noboundscheck erathos.d && time ./erathos
> 283146
>
> real    0m0.144s
> user    0m0.132s
> sys    0m0.008s
>

> So CTFE in the front end seems to be ~50 times slower than a optimized
> DMD build of the same code in this case. But note that it is powered by
> a simple-minded bytecode interpreter I hacked together mostly during two
> weekends.

Yes, yes and yes! Simple bytecode interpreter is what I've been waiting 
for :)

> (the array append is the one from druntime) A lot more is
> possible. I guess it is already fast enough to power std.regex.

Sure and a simple threaded-code interpreter should make it fly (when D 
has e.g. explicit tail call).

-- 
Dmitry Olshansky