fix loop unroll and jam - operand mapping - imperfect nest case

[bondhugula]

• fix operand mapping while cloning sub-blocks to jam - was incorrect for imperfect nests where def/use was across sub-blocks
• strengthen/generalize the first test case to cover the previously missed scenario
• clean up the other cases while on this.

Previously, unroll-jamming the following nest

    affine.for %arg0 = 0 to 2048 {
      %0 = alloc() : memref<512x10xf32>
      affine.for %arg1 = 0 to 10 {
        %1 = affine.load %0[%arg0, %arg1] : memref<512x10xf32>
      }
      dealloc %0 : memref<512x10xf32>
    }

would yield

      %0 = alloc() : memref<512x10xf32>
      %1 = affine.apply #map0(%arg0)
      %2 = alloc() : memref<512x10xf32>
      affine.for %arg1 = 0 to 10 {
        %4 = affine.load %0[%arg0, %arg1] : memref<512x10xf32>
        %5 = affine.apply #map0(%arg0)
        %6 = affine.load %0[%5, %arg1] : memref<512x10xf32>
      }
      dealloc %0 : memref<512x10xf32>
      %3 = affine.apply #map0(%arg0)
      dealloc %0 : memref<512x10xf32>

instead of

module {
    affine.for %arg0 = 0 to 2048 step 2 {
      %0 = alloc() : memref<512x10xf32>
      %1 = affine.apply #map0(%arg0)
      %2 = alloc() : memref<512x10xf32>
      affine.for %arg1 = 0 to 10 {
        %4 = affine.load %0[%arg0, %arg1] : memref<512x10xf32>
        %5 = affine.apply #map0(%arg0)
        %6 = affine.load %2[%5, %arg1] : memref<512x10xf32>
      }
      dealloc %0 : memref<512x10xf32>
      %3 = affine.apply #map0(%arg0)
      dealloc %2 : memref<512x10xf32>
    }

Signed-off-by: Uday Bondhugula uday@polymagelabs.com