This change introduces a thread-safe version of the 'SerializedDiagnosticConsumer' and refactors scanning compilation instance creation code to ensure this consumer gets added when the scanner query configuration command-line includes '-serialized-diagnostics-path' option.
Move per-query state out of ScanningService. There is still a check to
make sure the CASOptions are matching between queries because of the
requirement on clang scanner. Otherwise, the scanning service should
contain no per-query information anymore.
Resolves: https://github.com/swiftlang/swift/issues/82490
While this made sense in the distant past where the scanning service provided backing storage for the dependency cache, it no longer does so and now makes for awkard layering where clients get at the service via the cache. Now the cache is a simple data structure while all the clients that need access to the scanning service will get it explicitly.
- 'SwiftModuleScanner' will now be owned directly by the 'ModuleDependencyScanningWorker' and will contain all the necessary custom logic, instead of being instantiated by the module interface loader for each query
- Moves ownership over module output path and sdk module output path directly into the scanning worker, instead of the cache
Checking each module dependency info if it is up-to-date with respect to when the cache contents were serialized in a prior scan.
- Add a timestamp field to the serialization format for the dependency scanner cache
- Add a flag "-validate-prior-dependency-scan-cache" which, when combined with "-load-dependency-scan-cache" will have the scanner prune dependencies from the deserialized cache which have inputs that are newer than the prior scan itself
With the above in-place, the scan otherwise proceeds as-is, getting cache hits for entries still valid since the prior scan.
Batch dependency scanning was added as a mechanism to support multiple compilation contexts within a single module dependency graph.
The Swift compiler and the Explicitly-built modules model has long since abandoned this approach and this code has long been stale. It is time to remove it and its associated C API.
'ModuleDependencyScanner' maintains a Thread Pool along with a pool of workers
which are capable of executing a filesystem lookup of a named module dependency.
When resolving imports of a given Swift module, each import's resolution
operation can be issued asunchronously.
From being a scattered collection of 'static' methods in ScanDependencies.cpp
and member methods of ASTContext. This makes 'ScanDependencies.cpp' much easier
to read, and abstracts the actual scanning logic away to a place with common
state which will make it easier to reason about in the future.
Adopts Clang's 'DependencyScanningWorkerFilesystem' for use by the scanner, with the persistent
scanner instance keeping a 'DependencyScanningFilesystemSharedCache'.
This change causes the cache to be layered with a local "cache" that wraps the global cache, which will serve as the source of truth. The local cache persists only for the duration of a given scanning action, and has a store of references to dependencies resolved as a part of the current scanning action only, while the global cache is the one that persists across scanning actions (e.g. in `DependencyScanningTool`) and stores actual module dependency info values.
Only the local cache can answer dependency lookup queries, checking current scanning action results first, before falling back to querying the global cache, with queries disambiguated by the current scannning action's search paths, ensuring we never resolve a dependency lookup query with a module info that could not be found in the current action's search paths.
This change is required because search-path disambiguation can lead to false-negatives: for example, the Clang dependency scanner may find modules relative to the compiler's path that are not on the compiler's direct search paths. While such false-negative query responses should be functionally safe, we rely on the current scanning action's results being always-present-in-the-cache for the scanner's functionality. This layering ensures that the cache use-sites remain unchanged and that we get both: preserved global state which can be queried disambiguated with the search path details, and an always-consistent local (current action) cache state.
Adds a C API layer consisting of:
- Data structures used to represent in-memory result of dependency scanning
- Opaque dependency scanner tool (C wrapper for `DependencyScanningTool`)
Refactors `ScanDependencies.cpp` to produce dependency scanning result in the form of the above binary format.
This commit refactors ScanDependencies.cpp to split the functionality into two functional groups:
- Scan execution code that performs the mechanics of the scan and produces an in-memory result
- Dependency scanner entry-points used when the scanning action is invoked as a `swift-frontend` execution mode
This commit also adds the aforementioned in-memory dependency scanning result in `FullDependencies.h`, modeled after the InterModuleDependencyGraph representation in swift-driver
