[Bug target/60300] [avr] Suboptimal stack pointer manipulation for frame setup

[matthijs at stdin dot nl]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60300

--- Comment #3 from Matthijs Kooijman <matthijs at stdin dot nl> ---
Hmm, I don't think the gcc sources support that. AFAICT, they attempt to just
find the shortest approach, without caring for speed. For example, look at
avr.c, around line 1265, where it says:

              /************ Use shortest method ************/

              emit_insn (get_sequence_length (sp_plus_insns)
                         < get_sequence_length (fp_plus_insns)
                         ? sp_plus_insns
                         : fp_plus_insns);

https://github.com/mirrors/gcc/blob/c2e306f5efb32b7eed856a1844487cff09aa86ac/gcc/config/avr/avr.c#L1265-L1270