pytorch

6b3802a7 - [Gradient Compression] Export sizes, along with length and offset of each variable to GradBucket for PowerSGD (#47203)

[Gradient Compression] Export sizes, along with length and offset of each variable to GradBucket for PowerSGD (#47203) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/47203 1. Create a new field in BucketReplica to store sizes info for each variable. 2. Export sizes list, along with lengths and offsets to GradBuceket. These fields are needed for PowerSGD. Original PR issue: Investigate Applying PowerSGD to Communication Hook for Gradient Compression #47202 ghstack-source-id: 115875194 Test Plan: Checked the field values from log. Reviewed By: rohan-varma Differential Revision: D24644137 fbshipit-source-id: bcec0daf0d02cbf25389bfd9be90df1e6fd8fc56