[Bug target/117366] arm thumb1 epilogue size optimizer violates -ffixed

[matt.parks--- via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117366

--- Comment #1 from Matt Parks <matt.pa...@go-aps.com> ---
Side note - just to eliminate an undocumented magic number, I'd also suggest
the following diff in thumb1_extra_regs_pushed:
- while(reg_base + n_free < 8 && ...
+ while(reg_base + n_free <= LAST_LO_REGNUM && ...