Problems with dmd inlining

[Walter Bright]

Jason House wrote:
> Walter Bright Wrote:
> 
>> Jason House wrote:
>>> I wish I had your problems. I ported a sizable set of C++ code to D2 and 
>>> discovered D2 with dmd was 50x slower than C++ with gcc! I've been to 
>>> busy/disappointed to track down the bug(s) causing such a slowdown. If
>>> anyone is sufficiently inspired to find the bugs, I can make the GPL
>>> source code available.
>>> 
>> 50 times slower is not likely to be a problem with inlining, it's likely to
>> be an algorithmic one.
> 
> Normally, yes, I'd agree. But in this case, it's merely a port of the C++
> source code, so all algorithms are identical. The only change I did initially
> was to use ranges, but even after replacing those with mixins, the
> performance was equally as bad. There's also no memory allocations, so the GC
> isn't an issue either. There are also benchmarks on behavior that make me
> fairly confident the behavior is comparable.

There's something funky going on. Inlining can't explain anywhere near a 50x change.