https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55212
--- Comment #137 from Oleg Endo <olegendo at gcc dot gnu.org> ---
(In reply to Kazumoto Kojima from comment #136)
> Hope these observations help for clarifying issues.
Kaz, thanks so much for chiming in and looking at these after such a long time!
It's really appreciated!
My concern is that, LRA was supposed to make things _better_ than old reload.
But now we have to add even more hacks....
Perhaps some of the fixes should go into LRA itself -- in particular the one
for R0 in comment #135.
We already have the R0 constraint:
(define_insn "*extend<mode>si2_compact_mem_disp"
[(set (match_operand:SI 0 "arith_reg_dest" "=z,r")
^^^
.. your patch to add an explicit R0 clobber seems a good workaround, but also
shows that something in LRA land is not working properly, I think.
