This patch makes a few small, but key, changes to enable ccache on
Windows. First, it replaces the hendrikmuhs/ccache-action action with
command line invocations to the ccache binary, since the action has two
bugs, one of which causes CI to refer to different ccache artifacts
before versus after the build on Windows whereas the other bug can
sometimes cause the action to incorrectly infer that the cache is empty.
Second, this patch slightly alters the cache key, so that our old cache
artifacts, which have grown too big, are eventually discarded in favor
of the new, smaller cache artifacts. Along the way, this patch also
keeps the RollPyTorch's cache artifact separate from the regular build's
cache artifact so as to keep these artifacts small, and also because the
RollPyTorch action is off the critical path for most contributors.
Finally, this patch makes small changes to the CMake file so that on
Windows, the ccache binary is added as a prefix, as recommended on the
[ccache Wiki](https://github.com/ccache/ccache/wiki/MS-Visual-Studio).
* ci: update versions of external actions
Node.js 12 actions are deprecated and will eventually go away, so this
patch bumps the old actions to their latest versions that use Node.js
16.
* ci: replace deprecated action with bash commands
The llvm/actions/install-ninja action uses Node.js 12, which is
deprecated. Since that action is not updated to work with Node.js 16,
this patch replaces that action with equivalent bash commands to install
Ninja.
* ci: use smaller ccache artifacts to reduce evictions
Over time, our ccache sizes have grown quite large (some as large as
1.3 GB), which results in us routinely exceeding GitHub's limits, thus
triggering frequent cache evictions. As a result, cache downloads and
uploads take unnecessary long, in addition to fewer cache entries being
available.
Based on experiments on a clean cache state, it appears that we need
less than 300 MB of (compressed) ccache artifacts for each build type.
Anything larger than that will accrue changes from the past that aren't
needed.
To alleviate the cache burden, this patch sets the maximum ccache size
to be 300 MB. This change should not affect the success or failure of
our builds. I will monitor the build times to check whether this change
causes any performance degradation.
* ci: use consistent platform identifiers
Prior to this patch, some of our builds ran on `ubuntu-latest`, while
some others ran on `ubuntu-20.04` and others ran on `ubuntu-22.04`, with
similar situations for macOS and windows. This patch instead sets all
Linux builds to run on `ubuntu-latest`, all macOS builds to run on
`macos-latest`, and all Windows builds to run on `windows-latest`, to
make debugging future CI failures a little easier.
This enables building Pytorch from source in the CI.
The build should mostly hit the ccache.
Release builds will follow once we have some runtime on the CI.
Since they run in distinct jobs, using the same ccache would
cause one job to overwrite the cache of the other.
See https://github.com/ljfitz/torch-mlir/pull/16 for a proof
that this works. The first build takes a long time but ccache
takes over in the dummy commit.