On Fri, Oct 21, 2022 at 3:46 PM Takayuki 'January June' Suwa <jjsuwa_sys3...@yahoo.co.jp> wrote: > > This patch offers an additional allocable register by RA for the CALL0 > ABI. > > > Register a0 holds the return address upon entry to a function, but > > unlike the windowed register ABI, it is not reserved for this purpose > > and may hold other values after the return address has been saved. > - Xtensa ISA Reference Manual, > 8.1.2 "CALL0 Register Usage and Stack Layout" [p.589] > > gcc/ChangeLog: > > * config/xtensa/xtensa.cc (xtensa_conditional_register_usage): > Remove register A0 from FIXED_REGS if the CALL0 ABI. > (xtensa_expand_epilogue): Change to emit '(use (reg:SI A0_REG))' > unconditionally after restoring callee-saved registers for > sibling-call functions, in order to prevent misleading that > register A0 is free to use. > --- > gcc/config/xtensa/xtensa.cc | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-)
Regtested for target=xtensa-linux-uclibc, no new regressions. Committed to master. -- Thanks. -- Max
