Offhand, I don't have any cases. The cases where they're the most likely to occur is in the codegen pipeline, but codegen is already acknowledged to be a situa

Offhand, I don't have any cases. The cases where they're the most likely to occur is in the codegen pipeline, but codegen is already acknowledged to be a situation where you have non-optional passes that have to occur in a particular order, so I suspect you're already discounting those scenarios.