Why is this D code slower than C++?

[Bradley Smith]

Yes, I see that behavior too. Using doubles, here is what I get.

    dmc    6 sec
    dmd    19 sec
    gdc    17 sec
    msvc   4 sec

It is also interesting that the msvc gets better where the dmc gets 
worse. I wouldn't stake to much on it though, since these are 
approximate timings.

Thanks,
   Bradley

Daniel Giddings wrote:
> Try this version. In MSVC C++, float -> double, funcf -> func for the 
> floating funcs (sqrtf, expf). It improves the time from 8.6 to 5.7 
> seconds on my computer. The same process makes the D version slower.
> 
> Bradley Smith wrote:
>>
>> Bradley Smith wrote:
>>> As Bill Baxter pointed out, I missed an optimization on version 2. 
>>> The pass by reference optimization using the inout on the Intersect's 
>>> Ray argument. I had applied inout only to the Raytrace's Ray argument.
>>>
>>> The further optimization brings the following approx. timings:
>>>
>>>         time     factor
>>>   dmc    5 sec    1.0
>>>   dmd    9 sec    1.8
>>>   gdc    13 sec   2.6
>>     gdc    10 sec   2.0      <-- correction
>>>   msvc   5 sec    1.0
>>>   g++    doesn't compile
>>>
>>
>> Here is a correction to the gdc results. The wrong optimization flag 
>> was used. The build_d_gdc.bat should have "-O3" rather than "-O".
>