[Mlir-commits] [mlir] [mlir] Avoid rewriting unreachable blocks in the greedy driver (PR #225814)

[Matthias Springer]

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matthias-springer wrote:

What would happen if a pattern produces invalid IR that is later cleaned up again? E.g. let's say a block operand refers to a block from another region.

We currently phrase "Patterns should transform verifiable IR into verifiable IR" as a best practice and not a strict requirement. (That being said, I cannot think of a case where a user would write such a pattern.)

edit: I see that `notifyBlockInserted` already takes care of the case where a block is moved to another region. So the only other (edge) case that I can think of is: changing a block operand (`notifyOperationModified` would trigger).

https://github.com/llvm/llvm-project/pull/225814