pytorch

3264ba06 - observers: use clamp instead of min/max in calculate_qparams (#43150)

observers: use clamp instead of min/max in calculate_qparams (#43150) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/43150 The current logic was expensive because it created tensors on CUDA. Switching to clamp since it can work without needing to create tensors. Test Plan: benchmarks Imported from OSS Reviewed By: jerryzh168 Differential Revision: D23170427 fbshipit-source-id: 6fe3a728e737aca9f6c2c4d518c6376738577e21