Acyclic partition patch (#86511)
Fixes #86159 and #86108
Refactored graph partition to check for cyclic dependency on each partition merge, instead of relying on a pre-baked dependency map.
The previous implementation suffers from not updating dependency on existing partition. When a fusion happens, the updated dependency map needs to be propagated to all nodes in the graph, so each node in a partition shares an identical dependency set. Previous implementation suffers from the not identifying cyclic dependency in issue #86159.
Updated implementation does a cyclic check on partitioned graph before attempting a merge of two partitions.
- [x] python repro added with cyclic dependency after partition `TestFXGraphPasses.forward12`
- [x] fix dependency map with updated implementation using cyclic check
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86511
Approved by: https://github.com/SherlockNoMad
