* loop-iv.c (suitable_set_for_replacement): Renamed from
simplify_using_assignment; changed to return bool and to accept new
args DEST and SRC. Return true iff we find a source/destination pair
that can be used to make a replacement, and fill SRC and DEST if so.
Remove arg ALTERED. Don't deal with altered regs here. All callers
changed.
(simplify_using_initial_values): Deal with altered regs here and track
more precisely the effect they have on the validity of our expression.
From-SVN: r145351
