[Layout] Add layout transformation analysis for PrimFunc

[psrivas2]

This change adds a PrimFunc level analysis to propose layout transformations to block and buffers in the PrimFunc based on the layout transformations to PrimFunc outputs. It analyzes buffer access to figure this out. It tries to preserve sequential access to buffers when it does this.

For example given the following PrimFunc and write buffer "relu" transformation lambda n, c, h, w: (n, h, w, c // 4, c % 4), it will suggest to make the following transformations.

• Block transformation on "compute": lambda n, c, h, w: (n, h, w, c // 4, c % 4)
• Buffer transformation on "relu": lambda n, c, h, w: (n, h, w, c // 4, c % 4)
• Buffer transformation on "arg": lambda n, c, h, w: (n, h, w, c // 4, c % 4)

@T.prim_func
  def elemwise_relu(
      arg: T.Buffer((32, 64, 224, 224), "float32"),
      relu: T.Buffer((32, 64, 224, 224), "float32"),
  ):
      for i0, i1, i2, i3 in T.grid(32, 64, 224, 224):
          with T.block("compute"):
              v_i0, v_i1, v_i2, v_i3 = T.axis.remap("SSSS", [i0, i1, i2, i3])
              T.reads(arg[v_i0, v_i1, v_i2, v_i3])
              T.writes(relu[v_i0, v_i1, v_i2, v_i3])
              relu[v_i0, v_i1, v_i2, v_i3] = T.max(arg[v_i0, v_i1, v_i2, v_i3], T.float32(0))

These transformations can then be applied on the PrimFunc to get the PrimFunc with new layout.

@T.prim_func
def elemwise_relu(
    arg: T.Buffer((32, 224, 224, 16, 4), "float32"),
    relu: T.Buffer((32, 224, 224, 16, 4), "float32"),
):
    for ax0, ax1, ax2, ax3, ax4 in T.grid(32, 224, 224, 16, 4):
        with T.block("compute"):
            v0, v1, v2, v3, v4 = T.axis.remap("SSSSS", [ax0, ax1, ax2, ax3, ax4])
            T.reads(arg[v0, v1, v2, v3, v4])
            T.writes(relu[v0, v1, v2, v3, v4])
            relu[v0, v1, v2, v3, v4] = T.max(arg[v0, v1, v2, v3, v4], T.float32(0))

[tqchen]

#453, this PR should be part of PRs to send to unity. We can either directly transition to PR to unity, or continue review merge before transition, depending on what authors and reviewers want

[psrivas2]

cc @sunggg @masahi @YuchenJin

[psrivas2]

Migrated to unity branch apache/tvm#14066