[Bug target/69501] PowerPC rs6000_adjust_cost doesn't recognize float/sign/zero extend memory operations

[meissner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69501

--- Comment #1 from Michael Meissner <meissner at gcc dot gnu.org> ---
insn_is_load_p in rs6000.c probably also needs to be modified.