[Bug tree-optimization/78604] [7 regression] test case gcc.target/powerpc/p8vector-vectorize-1.c fails starting with r242750

[amker at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78604

--- Comment #4 from amker at gcc dot gnu.org ---
(In reply to amker from comment #3)
> For function sign_lt and uns_lt, the change causes worse code generation
> unfortunately.  Take uns_lt as example, the difference in optimized dump is

> So powerpc has to compute ">=" with "> || =="?  Apart from this, the change
> itself only introduces additional canonicalization during tree-ifcvt,
> transforming "<" to "<=".  If the former form is more efficient on powerpc,
> shall we take this into consideration when canonicalization?
In powerpc backend, function rs6000_emit_vector_cond_expr only inverts
unordered comparisons.  If I understand correctly, it could be improved to
handle more cases like this one.  So this is a backend issue?
Thanks.