Study: build times for D programs

[David Nadlinger]

On Thursday, 26 July 2012 at 18:59:14 UTC, Jonathan M Davis wrote:
> Clearly -O is where the big runtime speed difference is at 
> between dmd and gdc,
> which _is_ a bit obvious, but I'm surprised that -inline had no 
> differences,
> since dmd is generally accused at being poor at inlining. That 
> probably just
> indicates that it's a frontend issue (which I suppose makes 
> sense when I think
> about it).

GDC probably performs inlining by default on -O2/-O3, just like 
LDC does.

Also note that for the -release case (any performance 
measurements without it are most probably not worth it due to all 
the extra _d_invariant, etc. calls), -inline seems to increase 
the runtime of the DMD-produced executable by 10%. For inlining, 
you inevitably have to rely on heuristics, and there will always 
be cases where it slows down execution (worst case: the slight 
improvement in code size causes cache thrashing in a hot path), 
but 10% in a fairly standard application seems to be quite a lot.

David