[ODE] Autotools added to UNSTABLE

[Tanguy Fautre]

Rodrigo Hernandez wrote:
> Well, this is going to be tricky, I dont know whether it is posible to 
> pass separate flags to each source file, I know it is posible to pass 
> different flags for each target, so I guess I better start poking things 
> around, so what do you think would be a better default option while I 
> figure this out?
> passing -O1 o -O2 to everything? I figure -O1, but I though I should ask :)
> 

Now that's a tricky choice ;-).

Because of the code generation bug, OPCODE *must* be compiled with -O1. 
So if you're going to use the same compilation flags for ODE and OPCODE, 
you're probably better of with -O1 (although it may significantly slow 
down ODE :-( ). Otherwise OPCODE will be broken.

Now if you can specify compilation flag separately for OPCODE and ODE, 
it may be a nice idea to specify -O1 for OPCODE and -O2 for ODE.

I'm not sure how big is the performance difference with -O1 vs -O2 for 
ODE. I don't know ODE enough to know whether the auto-tuned *.c files 
are going to make ODE slower with -O2 instead of -O1 (used for ODE as a 
whole).

As a side note, I think it would be interesting to see how GCC 4.0 
performs with -O1/O2 on those autotuned *.c files.

Cheers,

Tanguy