What is the role of Elemwise.h(topi/include/topi)?

I added a compute in the tvm source code following the sigmoid. When detecting the dependencies of each file, I did not add a statement about sigmoid in elemwise.h, but found that there is no error after compiling the code, and the test case produces the correct result. .
But I found in intop.cc that intrin compute calls the function in elemwise.
At the same time, I would like to ask, is the order of calling tvm intrin op in the source code as follows?

Intrin_rule.cc–>intrin.py–>math.py–>elemwise.h–>topi.cc