There were two cache replay code exists, one for cache replay from
swift-frontend, the other for replay using C API from libSwiftScan. It
is easy to forget to update one copy when new specialized cache replay
logic is added for some output kinds. Now unify the replay logics to a
single location to avoid confusion. This is a rewrite of the existing
logic and NFCI.
The symbol graph output from a module can contain an arbitrary number of
files, depending on what extensions it contains, so cache a list of
symbol graph files with their base name and contents so that they can be
replayed.
rdar://140286819
Use IncludeTreeFileList instead of full feature CASFS for swift
dependency filesystem. This allows smaller CAS based VFS that is smaller
and faster. This is enabled by the CAS enabled compilation does not
need to iterate file system.
rdar://136787368
Fully support make-style `.d` dependencies file output by making
following improvements:
* All correct dependency file render when cache hit for a different
output file location. The dependency file should list the correct
output path, not the stale output path for the initial compilation
* When enable a path prefix mapper to canonicalize the path, the
dependency file should render the input file correctly as the input
file path on disk.
rdar://132250067
This patch adds support for MCCAS when a cache hit is encountered when
trying to replay a compilation, and uses the MCCAS serialization code
to materialize the object file that is the main output of the
compilation.
Add new APIs libSwiftScan that can be used for cache query and cache
replay. This enables swift-driver or build system to query the cache and
replay the compilation results without invocation swift-frontend for
better scheduling.
Update swift cache key computation mechanism from one cache key per
output, to one cache key per primary input file (for all outputs that
associated with that input).
The new schema allows fewer cache lookups while still preserving most of
the flexibility for batch mode and incremental mode.
Allow DependencyScanner to canonicalize path using a prefix map. When
option `-scanner-prefix-map` option is used, dependency scanner will
remap all the input paths in following:
* all the paths in the CAS file system or clang include tree
* all the paths related to input on the command-line returned by scanner
This allows all the input paths to be canonicalized so cache key can be
computed reguardless of the exact on disk path.
The sourceFile field is not remapped so build system can track the exact
file as on the local file system.
Rename `-enable-cas` to `-compile-cache-job` to align with clang option
names and promote that to a new driver only flag.
Few other additions to driver flag for caching behaviors:
* `-compile-cache-remarks`: now cache hit/miss remarks are guarded behind
this flag
* `-compile-cache-skip`: skip replaying from the cache. Useful as a
debugging tool to do the compilation using CAS inputs even the output
is a hit from the cache.
Teach swift dependency scanner to use CAS to capture the full dependencies for a build and construct build commands with immutable inputs from CAS.
This allows swift compilation caching using CAS.
