Some URLs for those who want to dig deeper into AltiVec:
Freescale's page as mentioned by bbrv (including the instruction set manuals for both assembly and C/C++):
http://www.freescale.com/webapp/sps/sit ... dGmKqW5Nf2
They also have the MPC7450 processor User Manual:
http://www.freescale.com/files/32bit/do ... 7450UM.pdf
And the PowerPC 32 bit assembler reference manual, for those who don't want to heed my advice to stick with C/C++
:
http://www.freescale.com/files/product/ ... FPE32B.pdf
and the corrections to this manual:
http://www.freescale.com/files/product/ ... E32BAD.pdf
Apple's page (with a thorough AltiVec tuning tutorial):
http://developer.apple.com/hardware/ve/
Ars Technica hosts Jon "Hannibal" Stokes' articles on pipelining in modern CPUs:
http://arstechnica.com/articles/paedia/cpu.ars
Then there is simdtech.org, which hosts some AltiVec files and the AltiVec mailinglist (with archives):
http://www.simdtech.org/altivec
There is still Ian Ollmann's original AltiVec tutorial floating around as PDF document, but it has since been superceded by Apple's online tutorial (Ian works at Apple these days).
Then there is my claim to fame, a table of optimal code sequences to create constant values in registers (this is not something you would need every day, but for ultimate tuning it can be handy. It somewhat alleviates AltiVec's lack of immediate operands):
http://www.informatik.uni-bremen.de/~ho ... tiVec.html
You will also need a good code profiler, but I don't know what is available on PowerPC Linux and/or MorphOS, so somebody else will have to supply that information. Just keep this thread going with more URLs!