[Bug target/97437] builtins subcarry and addcarry still not generate the right code. Not get optimized to immediate value

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97437

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
And fwprop that perhaps wouldn't "simplify" them that much punts on these
because the instructions are multiple sets.  It is unclear why, I mean, sure,
it can't be adding REG_EQUAL notes in that case, but otherwise why can't it
propagate at least constants to all the SET_SRCs of the pattern and try to
validate all the changes at once?