[Bug target/67391] [SH] Convert clrt addc to normal add insn

[olegendo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67391

--- Comment #4 from Oleg Endo <olegendo at gcc dot gnu.org> ---
(In reply to Kazumoto Kojima from comment #3)
> 
> Ugh, those checks look just wrong and I can't remind why I've
> added them.  33707 didn't do that and checked overlapping at
> the split condition only.  Perhaps I mixed up the final patch
> with the one of test codes to collect CSiBE results.  You can
> install the above patch as the rather obvious one, though I'm
> running "make -k check" on sh4-unknown-linux-gnu.  Sorry for
> adding that thinko.

No problem.  I'd like to wait for your test results though before committing.

I've just checked, the code is also present in GCC 5.  Because of the funny
side effects even with LRA disabled (this PR) I'd like to backport this to the
GCC 5 branch, too.