[Error] Unresolved call Op(tir.likely)

Hi I’am trying to understand how different scheduler primitive affect the code generation, however with below simple code I encountered the above error.

# tile test
A = te.placeholder((m, n), name="A")
B = te.compute((m, n), lambda i, j: A[i, j], name="B")
s = te.create_schedule(B.op)
xo, yo, xi, yi = s[B].tile(B.op.axis[0], B.op.axis[1], x_factor=10, y_factor=5)
# tvm.lower will show "tir.likely" code and I don't know what does it mean.
ir_m = tvm.lower(s, [A, B], simple_mode=True)
rt_m = tvm.build(ir_m, [A, B], target='c', name='test')
# print source code
print("source code:\n", rt_m.get_source())

Any help will be appreciated, basically 3 questions:

  1. where to find “tir.likely” document ?
  2. does C code gen support “tir.likely” ?
  3. If not in 2, how does it achieve to arrive the module compile stage ?

You can try simple_mode=False, simple mode disables some passes that are required for symbolic shape.