xla

c8b09f5f - Cache bazel builds with `--disk_cache` using GitHub cache action. (#9695)

Cache bazel builds with `--disk_cache` using GitHub cache action. (#9695) This PR addresses issue #9659, caching bazel build artifacts on `--disk_cache` using GitHub `cache` action. This should allow PRs from external repositories (i.e. forks) to benefit from build caching. That's because remote cache is only enabled for PRs from within `pytorch/xla` repository. In summary, this PR will add the following cache behavior: 1. Every commit pushed to `master` or any release candidate branch (e.g. `rX.X`) will: - Create a new disk cache - Populate the cache as it builds PyTorch/XLA - Save the populated disk cache, associating it with the current branch, and the current commit 2. Every PR on branch `X` (either `master` or a release candidate branch) will: - Try to restore the cache associated with `X` at the commit it's trying to merge with - Build PyTorch/XLA using the restored disk cache - If we don't actually find a cache to restore, we won't use a disk cache Note that we only have 10GB of cache storage. So, in order to minimize it, I made the following decisions: - The disk caches created in (1) won't restore any cache in the beginning - Smaller caches - The disk caches restored in (2) won't be saved in the end - Fewer caches