Mail Archives: djgpp/1997/06/03/09:45:50
> >it is very easy to crash. Try compiling a floating point
> >using program with -ffast-math -funroll-loops. Watch it SIGFPE.
>
> Why does it do that, a bug?
Yep. I believe that -ffast-mast -mno-ieee is broken in the
FSF snapshot. Also -funroll loops. Several of the more
obscure pentium only options don't work right now from the PCG
stuff. But, everything that is enabled by -O6 does work.
> >all of the optimizations have been accepted by the FSF ( I know the
> >schedule-insns2 is the PCGs but aside from that not sure...).
>
> What optimizations specifically?
There are a lot, you would have to check the PCG faq. It has details.
>
> >> (POV uses DJGPP?! I never knew that.)
> >
> >The default DOS binary provided is compiled by Watcom. The source
> >distribution (for DOS) works with Watcom, Borland, DJGPP, and others.
>
> How does that work... it uses graphics for godsakes. Conditional compilation?
> Also, which compiler makes the fastest POV, Watcom, Borland, or PGCC?
>
POVRay is also supported on Unix systems, as well as Mac and Amiga I
believe. But yes, they use conditional compilation. The DJGPP version
doesn't have a UI like Watcom, but it can still render to a VESA 2.0
driven screen.
WRT Fastest - I'm not a normal POVRay user. I just picked it up as
something good to test with. Maybe some other DJGPPers could
post benchmark results...
> >> How did Pentium-optimized Allegro perform?
>
> >Slight improvement.
>
> Slight? Well, of course a lot is already Pentium-optimized asm.
> What about the 3d?
Don't know haven't written anything using the allegro 3D stuff.
> >> (Would using PGCC affect Allegro much? Much of it, except the 3d stuff, is
> >> assembly.
>
> >Yep - PGCCs no help here
>
> Optimizer won't touch files already in asm then?
Nope. A static code analyzer would, but I don't think GCC has ever used one
of those. All optimization is done from the .c->.s step.
>
> >> Is the assembly in Allegro's .S files pentium-optimal?)
>
> >Its pretty good assembly, but can be improved for pentium and pentium pro.
>
> Can it be? Has anyone taken a whack at that?
The new GCC comes with a new profiling program called gcov (gnu coverage).
Its kind of like BFA. I am also going to write up a tutorial
for the Pentium MSR optimization techniques. I was planning
on working on a section of Allegro for it. I should be done in a
month or so.
Andrew
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