Hi Holger, Ian,
Thanks for the tips! :-)
> 1) Optimizer is turned on. Xcode/ProjectBuilder have multiple places
> where a -O0 might sneak into your otherwise -O3 build.
For now, Xcode isn't involved, gcc 3.3 -O3 is used in command line.
[snip]
> though it can be more readable if you do it the way Holger suggested.
> Note that reordering non-dependent lines of C code on an optimizing
> compiler typically has no significant effect -- the compiler is going
> to reorder them the way it wants to anyway. One just has to be able to
> predict what the compiler will think is dependent and what is not, and
> order the dependent stuff the way you think will lead to the best speed
> improvement.
Yes, I just realized this.
gcc 3.3 re-ordered the instructions the way it wants.
Since it seems like a direct mapping from the AltiVec C to AltiVec assembly
for what I need to do, I plan to re-write the part in in-line assembly.
Could somebody recommend examples of (Altivec) in-line assembly in C?
> All bets are off with GCC-2.95. That would sometimes spontaneously
> decide that it only had 8 or 24 vector registers and spill accordingly.
> Get a newer compiler.
I'm using gcc 3.3. I guess you already know this by now. :-)
Thanks! happy Halloween
Stan.
_______________________________________________
Do not post admin requests to the list. They will be ignored.
PerfOptimization-dev mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/perfoptimization-dev/email@hidden
This email sent to email@hidden
