tree 4de94bd588a5177e6148b46c32be589fd235d970
parent 5c64255f32275911f0b4805701d72630488e5465
author Michael Gester <mgester@google.com> 1638294634 -0800
committer TensorFlower Gardener <gardener@tensorflow.org> 1638295127 -0800

Clean up Embedding op side effect handling

- now we have two Embedding side effects, read and write
- now dependencies between EnqueueTPUEmbedding ops with same device ordinal are
  properly modeled
- we now finally don't have any Embedding-specific code left in side effect
  analysis
- introduced new `TF_MustExecute` trait that avoids pruning of an op; this is
  useful for side-effecting ops that don't produce any output and don't have
  dependencies to/from other ops
- for ops that just used `TF_TPUEmbeddingSideEffect` to avoid pruning, use new
  `TF_MustExecute` trait instead
- in contrast to the old `TF_TPUEmbeddingSideEffect`, `TF_MustExecute` avoids
  pruning independent of reachability (see new graph pruning test)

PiperOrigin-RevId: 413175982
Change-Id: I7b65c7a0e8a17b8a1683a0e01d1fd0614f7ac95a