[Bug target/117818] [13/14/15/16 regression] vec_add incorrectly generates vadduwm for vector char const inputs.

[segher at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117818

--- Comment #12 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Hrm, yeah, the ISA says bits 57..63 of VRB.  That seems wrong, 121..127 is more
logical.  Let me test what existing hardware does.