[SelectionDAG] Remove an early-out from computeKnownBits for smin/smax
Even if we know nothing about LHS, it can still be useful to know that
smax(LHS, RHS) >= RHS and smin(LHS, RHS) <= RHS.
Differential Revision: https://reviews.llvm.org/D87145
foad on Sep 3 2020, 11:22 AM.Authored by