The buffer deallocation pass checks the IR ("operation preconditions")
to make sure that there is no IR that is unsupported. In such a case,
the pass signals a failure.
The pass now rejects all ops with unknown memory effects. We do not know
whether such an op allocates memory or not. Therefore, the buffer
deallocation pass does not know whether a deallocation op should be
inserted or not.
Memory effects are queried from the `MemoryEffectOpInterface` interface.
Ops that do not implement this interface but have the
`RecursiveMemoryEffects` trait do not have any side effects (apart from
the ones that their nested ops may have).
Unregistered ops are now rejected by the pass because they do not
implement the `MemoryEffectOpInterface` and neither do we know if they
have `RecursiveMemoryEffects` or not. All test cases that currently have
unregistered ops are updated to use registered ops.
Since ownership based buffer deallocation requires a few passes to be run in a somewhat fixed sequence, it makes sense to have a pipeline for convenience (and to reduce the number of transform ops to represent default deallocation).
Add a new Buffer Deallocation pass with the intend to replace the old
one. For now it is added as a separate pass alongside in order to allow
downstream users to migrate over gradually. This new pass has the goal
of inserting fewer clone operations and supporting additional use-cases.
Please refer to the Buffer Deallocation section in the updated
Bufferization.md file for more information on how this new pass works.
