Re: [avr-gcc-list] saving __zero_reg__ in interrupt

[Marek Michalkiewicz]

> both gcc 2.97 and 2.95 save, clear and restore the __zero_reg__
> in interrupt routines. (-->6 Bytes for each interrupt).
> Saving/restoring seems redundant as this register 
> should hold (holds) zero anyway.

It is not - some code (generated by avr-gcc, or hand-optimized assembler)
uses this register as a second temporary register (it's OK as long as you
zero it after use).  Interrupt comes in at the right moment (when r1 is
nonzero) and you lose.

> Is there a way to switch off this behaviour?

Don't ;)

Marek