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

[Mehdi Amini]

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joker-eph wrote:

`markBlockErased` is called from `notifyBlockErased`, which receives an existing block before destruction. `RewriterBase::eraseBlock` already dereferences that pointer before sending the notification, so a null block isn’t supported there.

`markBlockChanged` instead receives `op->getBlock()`, which can be null for a detached operation. The parent region can still be null in the erased-block case, which is why that separate check remains.

I can document these API contracts...

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