[Bug target/113623] [14 Regression] ICE in aarch64_pair_mem_from_base since r14-6605

[acoplan at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113623

--- Comment #3 from Alex Coplan <acoplan at gcc dot gnu.org> ---
I think ldp_fusion is exposing a latent issue here.  We trip the assert:

gcc_assert (aarch64_mem_pair_lanes_operand (mem, pair_mode));

on the RTL:

(rr) pr mem
(mem/f:V2x8QI (reg:DI 63 v31) [0 +0 S16 A64])

because v31 isn't a valid base register according to
aarch64_regno_ok_for_base_p.  This comes from the following RTL in sched1,
where we already have:

   30: x0:DI=[v31:DI]
   29: x1:DI=[v31:DI+0x8]

but again these mems look invalid as per aarch64_regno_ok_for_base_p.