The `OwnershipBasedBufferDeallocation` pass crashes when the IR contains
memrefs that are live in the same Block but are defined in different
Blocks. During this pass, live memrefs in a given block are sorted
according to the comparison function `ValueComparator`. This causes an
assertion to be triggered when sorting memref values using
`ValueComparator` as the comparison function. The assertion triggered is
found in `Operation::isBeforeInBlock`, which requires `this` and `other`
to reside in the same block. (See the definition
[here](https://github.com/llvm/llvm-project/blob/main/mlir/lib/IR/Operation.cpp#L385-L386).)
The fix is to handle values from different blocks in the
`ValueComparator` by sorting based on Block number if the compared ops
aren't in the same block. While `computeBlockNumber` is intended for
debugging and error messages, it is a convenient utility that can
provide a sufficient weak ordering for `llvm::sort` while handling
operations from different parent blocks. I'm not aware of another
ordering relation for Blocks that would be appropriate as well as cheap
to compute here.
I've added a test to exercise this that would fail otherwise. As I was
already editing the test file, I thought I would refactor it according
to the recommendations of the [MLIR Testing
Guide](https://mlir.llvm.org/getting_started/TestingGuide/#contributor-guidelines)
Fixes#137342Fixes#116363
47331ae735