best ABI strategy ?

[Aurelien Buhrig]

Hi,

I'm trying to optimize our target ABI, and I'm wondering what is the
best strategy to define it.
Is there a paper, or any hint, dealing with this topic ?
For instance,
- which ratio between call-used-reg vs "static regs"
- which ratio between arg regs vs call-used-reg
- what should be return regs
- ...
I guess this problem is very target dependent, but there are maybe
general ideas about this.


In particular, for now my call-used regs set is the same that arg regs
set. I noticed GCC would not use arg regs for reloading, (or would
prefer others), even if they are not actually used by function args.
and it generates extra push/pop of static regs. I there a way force
gcc preferring using "free" arg regs ?

Thank you by advance!

Aurélien