narrowed down the problem area

[Tim Burrell]

downs wrote:
> Tim Burrell wrote:
>> downs wrote:
>>>> Strangely, Vec v = void; Vec.sub(center, ray.orig, v); runs in 8.8s, producing a correct output once the printf at the bottom has been fixed,
>>>> but Vec v = center - ray.orig; runs in 11.1s.
>>> For some reason, the bad case, although inlined, stores its values back into memory. The fast case keeps working with them.
>>>
>>> So it comes down to a GDC FP "bug". I think changing to 4.2 or 4.3 might help. Does anybody have an up-to-date version of the 4.2.x patch?
>> 
>> Hey good deal on figuring this out!  It's good to know, especially for
>> those of us using D for real-time simulation type stuff.
>> 
>> Is there really a GDC that compiles against gcc >= 4.2?!
> 
> I'm not sure; I remember somebody saying he'd managed to build it. And there's a post on d.gnu from somebody saying he'd gotten it to work, although he couldn't build phobos.
> 
> Since GDC seems to be .. inert at the moment, it'd probably up to some volunteer effort to upgrade it to 4.[23]. That, or get llvmdc up to speed.
> 
> Myself of course is mostly clueless about both compilers. :/

I notice that the Ubuntu team appears to have a working 4.2 based gdc
that the changelog also says works with 4.3:

http://packages.ubuntu.com/hardy/devel/gdc-4.2

Changelog is here:
http://changelogs.ubuntu.com/changelogs/pool/universe/g/gdc-4.2/gdc-4.2_0.25-4.2.3-0ubuntu1/changelog

It'd be really nice to see a new gdc release!

I wonder if David even knows about these patches!?