AVR prologue & epilogue

[Svein E. Seldal]

Hi,

I'm working with some code targetted for the AVR platform. In an 
interrupt service routine, I need to switch stack just _prior_ to the 
push'es of this routine and then switch back the stack just after the 
pop's of the function. (This switch code is written assembly.)

1) Are there any ways I can insert some code before the push'es and 
after the pop's of a function (yet still before the ret[i] in the latter 
case)?

According to my reading of gcc/config/avr/avr.c it does not seem like 
this is possible, as the epilogue and the prologue seems very hardcoded.

So my second approach would be to declare the interrupt func as naked, 
but then my problem is that I need to manage myself which registers are 
clobbered and which are not.

2) Is there a way for me to instruct gcc to manually insert push's and 
pop's before and after a function i called. Does something like this exist:

	__builtin_push_used_regiserter();
	do_some_func();
	__builtin_pop_used_registers();


Regards,
Svein