[Bug target/64580] very high rs6000_stack_info() usage during LTO Firefox build on ppc64

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64580

--- Comment #3 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Hi again,

Unfortunately it seems I am unable to build a version of GCC that is
compatible with that (every version I tried either complains or ICEs).

Maybe you can answer the above questions yourself?  How often
is rs6000_output_mi_thunk called (+ some sense of scale, e.g.
how many "real" functions are emitted)?  Is there a real hotspot
in rs6000_stack_info itself?  I haven't been able to get it above
0.16% of cpu time, and no hotspots.

Can perf be used to analyze results on a different machine than
used to generate the data?