[Bug target/61298] redundant compare instructions for powerpc64

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61298

--- Comment #5 from Peter Bergner <bergner at gcc dot gnu.org> ---
(In reply to baoshan from comment #4)
> Yes, SUBREG_PROMOTED_UNSIGNED_P is supposed to be set for this case, it has
> been set originally, but the setting is lost while doing mode converting in
> function convert_modes():expr.c, do you think the following code is good
> enough to fix this issue?

I would post the patch and see what the rtl maintainers think.
I do know I had a lot of problems with my earlier patch of having
the TYPE_UNSIGNED() bit being lost and had to patch a few places
to ensure it was propagated correctly.  I wouldn't doubt that you
are having the same issue.