[Bug target/64379] VFP register restore in ARM epilogue can break indirect tailcalls

[donn.seeley at windriver dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64379

--- Comment #7 from Donn Seeley <donn.seeley at windriver dot com> ---
Re -mapcs-frame:  Yes, the failure is due to code in
arm_expand_epilogue_apcs_frame() that explicitly requires / stomps on IP in
order to restore VFP/NEON registers.  Sorry, I should have mentioned that.  The
indirect tailcall register is chosen from CALLER_SAVE_REGS via the "Cs"
constraint, and CALLER_SAVE_REGS contains the arg regs plus IP; if the arg regs
are in use, then the tailcall register ends up being IP.  Hence the conflict.