[Bug target/71709] powerpc64le: argument to strcpy() optimised out

[amodra at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71709

--- Comment #7 from Alan Modra <amodra at gmail dot com> ---
find_call_crossed_cheap_reg is certainly confusing.  On looking at it again
this morning, I can't see why it uses reg_overlap_mentioned_p to break out of
the loop.  Who cares if the reg is referenced (except autoinc)?  I'm thinking
now that the correct exit condition is simply reg_set_p (reg, prev).