[Bug target/103302] wrong code with -fharden-compares

[aoliva at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103302

--- Comment #9 from Alexandre Oliva <aoliva at gcc dot gnu.org> ---
Thanks, this alternate testcase confirms my suspicion that the original issue
was only going latent.  It's clearly a preexisting register allocation issue on
riscv, that was latent and that -fharden-compares exposed rather than
introduced.

If I understand correctly its pervasiveness, it may very well make
-fharden-compares too risky to use on riscv, so I may be on the hook to fix it
regardless.

ISTM that a post-reload insn_and_split would at least avoid the problem.  Is
there any reason why this approach is not in use on riscv?