pytorch

e05ee4c4 - Remove BUILD_NAMEDTENSOR macros (#30894)

Remove BUILD_NAMEDTENSOR macros (#30894) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/30894 This PR begins the process of removing BUILD_NAMEDTENSOR macros. There will be followups. Reasons for removing the macros: - BUILD_NAMEDTENSOR is always on and has been on since pytorch 1.3.0. - Since we don't test building without it, it is useless to keep around. - Code becomes nicer to read without the macros Reasons for not removing the macros: - potential for feature flagging Now, I argue against needing to feature flag. The main reason why we might want to feature flag is if we need to disable the feature. We'd need a fast switch to disable the feature if someone discovers in the future that named tensors caused some regression in some existing workflows. In https://github.com/pytorch/pytorch/pull/25798, I did a variety of macro- and micro- benchmarks to determine the performance impact of named tensors on regular tensors. [The microbenchmarks](https://github.com/pytorch/pytorch/pull/25798#issuecomment-529014810) were not very stable, and running the microbenchmarks for more iterations doesn't actually help because the noise is not distributed in a nice way. Instead of microbenchmarks I ran a [profiler (perf)](https://github.com/pytorch/pytorch/pull/25798#issuecomment-555707645) to estimate how much overhead named tensors add to unnamed code. I estimated the overhead to be less than 100ns for `add` and even smaller for `mm`; there are ways to optimize even futher if we find this to be a problem. [Initial macrobenchmarks](https://github.com/pytorch/pytorch/pull/25798#issuecomment-530539104) were also not very stable. I ran imagenet for some number of epochs. To make them more stable, I got rid of the data loading (which seemed to vary between runs). [In some benchmarkers without data loading](https://github.com/pytorch/pytorch/pull/25798#issuecomment-562214053), we can see that the results are less noisy now. These results support no noticeable regressions in speed. Test Plan: - wait for CI Differential Revision: D18858543 Pulled By: zou3519 fbshipit-source-id: 08bf3853a9f506c6b084808dc9ddd1e835f48c13