Piers Cawley wrote:
Dan Sugalski <[EMAIL PROTECTED]> writes:
There are ways to get around that, and there are some inefficiencies in the implementation there. I think we can work around some of those--I am rather tempted to have invoke promise not to alter non-parameter registers or something so you don't have to pushall every time you make a call to what could be assumed to be an atomic and non-parrot function.
Doesn't that rather invalidate the whole 'caller saves' principle?
The 'caller save' principle is IMHO subotimal. The caller doesn't know, how a sub is implemented, so has always to save everything. When the called sub is responsible for preserving the environment, only a minimal set of needed registers can be saved in the sub.
I would vote for above "non-parameter registers are preserved".
BTW imcc needs some extensions:
- subroutine return values in registers are OUT params WRT the invoke call, which imcc isn't aware of
- popX/clearX/restoreall do change registers, though this isn't flagged in the opcode.
imcc assumes, that all registers are preserved over function calls.
leo
