[Mlir-commits] [mlir] [mlir][llvm] Drop unreachable basic block during import (PR #78467)

[Tobias Gysi]

gysit wrote:

I prototyped a version that imports the code as is without deleting the unreachable blocks. It turns out to be quite tricky to get right since the change interferes with the error handling of the import. In particular, the `convertValue` method is used in different contexts and only in some of them it is ok to introduce a placeholder value. After the import, the unreachable blocks either way need to be deleted since the conversion infrastructure does not support them AFAIK.

As this PR fixes an existing bug, I suggest to land it (it is definitely an improvement over the status quo). Once we have a concrete use case, we can follow up with an version that introduces placeholder variables to support self-referencing instructions.


https://github.com/llvm/llvm-project/pull/78467