[LAD] GCC Vector extensions

[Maurizio De Cecco]

On Monday25/7/11 2:45 PM, Robin Gareus wrote:

> Thanks for coming up with and sharing the tests!

Thanks for trying :->

> would need to look into asm output.

As Stéphane said, i have to generate the assembler code.
I'll modify the scripts and send the assembler generated assembler code 
later.

> BTW. I'm pretty much impressed that some tests run faster on vmware
> virtualization compared to native OSX. But yeah it's also no big
> surprise either (and may further be related to ubuntu using a never
> version of gcc).

Yes, the compiler is different, and the code is a lot faster with more 
recent gcc versions. Apple froze the environment to gcc 4.2 waiting for 
clang. And, afaik, there is no reason for a vm to be slower in 
computational code than the real iron, qs long as no system calls are done.

> So are you now considering use some #ifdef to select float/4 instead of
> double/8 vectors in jMax or just change all of them?

Well, at the moment on gcc the perfomance with vector types is the same 
as without vector types, so i'll leave the Linux version without vector 
types (the code is #ifdef'ed).

It seems that it would be interesting to compile jMax with clang,
vector types and vector size 8 vector; i tried, but i find a lot of 
problems with include files (a lot of system level includes are not 
found by clang). I'll investigate this later :->.

By the way, i forgot to mentions that all my tests where at 64 bits; 
i'll try later on a 32 bit Ubuntu.


About the -funroll-loops and the various buffer strategies, i'll give a 
try and report later ..

Maurizio