Document inplace_on_inputs method and remove TODO comment

Co-authored-by: ricardoV94 <[email protected]>

Author: Copilot

doc/extending/inplace.rst

@@ -206,6 +206,45 @@ input(s)'s memory). From there, go to the previous section.
    Consider using :class:`DebugMode` when developing
    a new :class:`Op` that uses :attr:`Op.view_map` and/or :attr:`Op.destroy_map`.
 
+The `inplace_on_inputs` Method
+==============================
+
+PyTensor provides a method :meth:`Op.inplace_on_inputs` that allows an `Op` to
+create a version of itself that operates inplace on as many of the requested
+inputs as possible while avoiding inplace operations on non-requested inputs.
+
+This method takes a list of input indices where inplace operations are allowed
+and returns a new `Op` instance that will perform inplace operations only on
+those inputs where it is safe and beneficial to do so.
+
+.. testcode::
+
+   def inplace_on_inputs(self, allowed_inplace_inputs: list[int]) -> "Op":
+       """Try to return a version of self that tries to inplace in as many as `allowed_inplace_inputs`."""
+       # Implementation would create a new Op with appropriate destroy_map
+       # Return self by default if no inplace version is available
+       return self
+
+Currently, this method is primarily used with Blockwise operations through PyTensor's
+rewriting system, but it will be extended to support core ops directly in future versions.
+The rewriting system automatically calls this method to optimize memory usage by
+enabling inplace operations where they do not interfere with the computation graph's
+correctness.
+
+When implementing this method in a custom `Op`:
+
+- Return a new instance of your `Op` with a :attr:`destroy_map` that reflects
+  the inplace operations on the allowed inputs
+- Ensure that inplace operations are only performed on inputs that are in the
+  `allowed_inplace_inputs` list
+- Return `self` if no inplace optimization is possible or beneficial
+- The returned `Op` should be functionally equivalent to the original but with
+  better memory efficiency
+
+.. note::
+   This method is automatically used by PyTensor's optimization pipeline and typically
+   does not need to be called directly by user code.
+
 Inplace Rewriting and `DebugMode`
 =================================
 

pytensor/graph/op.py

@@ -605,7 +605,6 @@ def make_thunk(
 
     def inplace_on_inputs(self, allowed_inplace_inputs: list[int]) -> "Op":
         """Try to return a version of self that tries to inplace in as many as `allowed_inplace_inputs`."""
-        # TODO: Document this in the Create your own Op docs
         # By default, do nothing
         return self