Add a transform to make `tensor.pad` and `tensor.empty` ops independent of SCF loop IVs. Such ops can then be hoisted.

E.g.:

scf.for %iv = %lb to %ub step %step { %high = affine.apply affine_map<(d0)[s0] -> (s0 - d0)> (%i)[%ub] %p = tensor.pad %t low[5] high[%high] ... ... }

Is transformed to:

%high_new = affine.apply affine_map<()[s0, s1] -> (-s0 + s1)> ()[%lb, %ub] %p_hoistable = tensor.pad %t low[5] high[%high_new] %dim = tensor.dim %t, %c0 %size = affine.apply affine_map<(d0)[s0, s1] -> (-d0 + s0 + s1 + 5)>(%iv)[%ub, %dim] %slice = tensor.extract_slice %p_hoistable [0] [%size] [1]

Depends On: D146524