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digitalmars.D - staticIndexOf is incredibly slow and memory intensive

reply Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
Maybe this is CTFE to blame more than the function itself.

I have a project where I have a TypeTuple that holds a class tree of a
wrapped C++ library. The tuple is iterated from in several places
where an index has to be retrieved. Compiling this project takes 46
seconds when using staticIndexOf and uses 700 MB RAM. If I replace it
with my own hardcoded function below it takes only 5 seconds and uses
150 MB RAM. This is what the function looks like:

template myStaticIndexOf(T, TList...)
{
    static if (is(typeof(T == TList[0])) && is(T == TList[0]))
        enum myStaticIndexOf = 0;
    else
    static if (is(typeof(T == TList[1])) && is(T == TList[1]))
        enum myStaticIndexOf = 1;
    else
    // ... and so on ...
}

The body is pregenerated of course, using mixin() would slow down
compilation here as well.

When wrapping larger libraries (and hence having a larger TypeTuple)
and using staticIndexOf the memory usage becomes so high that the
compiler runs out of memory and crashes.

I really think it sucks that I have to resort to manually
pre-generating a function body externally as if I were using a lame
(CTFE-wise) language like C++03.

D *has* to be better than this..
Aug 26 2012
parent reply "Peter Alexander" <peter.alexander.au gmail.com> writes:
On Sunday, 26 August 2012 at 21:03:31 UTC, Andrej Mitrovic wrote:

 Maybe this is CTFE to blame more than the function itself.

 I have a project where I have a TypeTuple that holds a class 
 tree of a
 wrapped C++ library. The tuple is iterated from in several 
 places
 where an index has to be retrieved. Compiling this project 
 takes 46
 seconds when using staticIndexOf and uses 700 MB RAM.


Do you have a minimal repro case for this? It makes it a lot 
easier to track down the problem if we have a solid repro case 
that we can test.
Aug 26 2012
parent Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
On 8/26/12, Peter Alexander <peter.alexander.au gmail.com> wrote:

 Do you have a minimal repro case for this?


http://dpaste.dzfl.pl/4a267350

win32 using timeit:

$ timeit dmd -version=OLD myStaticIndex.d
Done in 626 msecs.

$ timeit dmd -version=NEW myStaticIndex.d
Done in 183 msecs.
Aug 26 2012