SelectionDAG: Select min/max when both are used

Allow two users of the condition if the other user
is also a min/max select. i.e.

%c = icmp slt i32 %x, %y
%min = select i1 %c, i32 %x, i32 %y
%max = select i1 %c, i32 %y, i32 %x

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269699 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed