[Grappler] RemoveIdentityTranspose also removes conjugate

[jheymann85]

• Have I written custom code (as opposed to using a stock example script provided in TensorFlow): yes
• OS Platform and Distribution (e.g., Linux Ubuntu 16.04): Linux Ubuntu 18.04
• Mobile device (e.g. iPhone 8, Pixel 2, Samsung Galaxy) if the issue happens on mobile device: N/A
• TensorFlow installed from (source or binary): binary
• TensorFlow version (use command below): 1.13
• Python version: 3.6
• Bazel version (if compiling from source): N/A
• GCC/Compiler version (if compiling from source): N/A
• CUDA/cuDNN version: 10.0
• GPU model and memory: N/A
• Exact command to reproduce: see below

During graph optimization, RemoveIdentityTranspose also removes a transpose if it conjugates the input (see here)

Simple example:

import tensorflow as tf
with tf.Graph().as_default():
    sess = tf.Session()
    a = tf.placeholder(tf.complex64)
    data = [[1j], [1j]]
    print(sess.run(tf.transpose(a, (0, 1), conjugate=True), {a: data}))  # not optimized
    print(sess.run(tf.transpose(a, (0, 1), conjugate=True) + 1, {a: data}))  # optimized, no conjugate will be applied
    print(sess.run(tf.conj(a) + 1, {a: data}))

Output:

[[0.-1.j]
 [0.-1.j]]
[[1.+1.j]
 [1.+1.j]]
[[1.-1.j]
 [1.-1.j]]

This can happen when using einsum/tensordot and a probably related issue is #19771

A possible fix would be to also check for IsConjugateTranspose here

[mohantym]

Hi @jheymann85 ! PR #40223 has fixed this issue. Attaching resolved gist for reference. Can we move this issue to closed status now? Thanks!

[google-ml-butler]

This issue has been automatically marked as stale because it has no recent activity. It will be closed if no further activity occurs. Thank you.

[google-ml-butler]

Closing as stale. Please reopen if you'd like to work on this further.

[google-ml-butler]

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