[Bug target/49881] [AVR] Inefficient stack manipulation around calls

[eric.weddington at atmel dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49881

--- Comment #1 from Eric Weddington <eric.weddington at atmel dot com> 2011-07-27 23:13:31 UTC ---
(In reply to comment #0)
> Created attachment 24848 [details]
> Hack to set ACCUMULATE_OUTGOING_ARGS
> 
> While looking at PR49864 I noticed some awful code.
> 
> First, the argument setup code doesn't use push:
> 
>         rcall .
>         rcall .
>         rcall .

Please note that the rcall instruction has a side effect of subtracting 2 bytes
from the SP (or 3 bytes if the avr device has a 22-bit PC). This side effect is
used in doing the "rcall ." instructions as an optimization to avoid doing 2
pushes (the rcall and push instructions are the same size).

But I agree that the code looks bad, and you show an improvement.

Where is this test case that you're referring to? I can only find your patch at
this PR, and only a patch at PR49864.

Thanks,
Eric Weddington