[Static Runtime] Fix bug in ClipRangesGatherRangesX2SigridHash (#53799)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53799
Fix two issues with ClipRangesGatherRangesX2SigridHash and ClipRangesGatherRangesX2SigridHashPrecompute:
- The first issue is with the two step graph rewrite process. If step 2 doesn't happen after step 1, then we're stuck with a graph with a `fb::placeholder` op that can't run. Step 3 is added to revert step 1 so we restore the original graph if there's any `fb::placeholder` op left.
- The second issue is with `SigridHashPrecompute`. The coupling with `freeze_module` is not ideal and limits its use to Static Runtime only. By running `ConstantPropagation` and `ConstantPooling` after splitting SigridHash, we can move all the Constant ops to the front of the graph and fusion can happen right afterwards.
Reviewed By: ajyu
Differential Revision: D26920008
fbshipit-source-id: e4bc67c7a15181bac5dbbfbb95d861849652bddf
