Clients of the dependency scanning service may need to add dependencies
based on the visibility of importing modules, for example, when
determining whether a Swift overlay dependency should be brought in
based on whether there's a corresponding **visible** clang module for
it.
This patch introduces a new field `VisibleModules` that contains all the
visible top-level modules in a given TU.
Because visibility is determined by which headers or (sub)modules were
imported, and not top-level module dependencies, the scanner now
performs a separate DFS starting from what was directly imported for
this computation.
In my local performance testing, there was no observable performance
impact.
resolves: rdar://151416358
---------
Co-authored-by: Jan Svoboda <jan@svoboda.ai>
While the source code isn't supposed to change during a build, in some
environments it does. This adds an option that disables caching of stat
failures, meaning that source files can be added to the build during
scanning.
This adds a `-no-cache-negative-stats` option to clang-scan-deps to
enable this behavior. There are no tests for clang-scan-deps as there's
no reliable way to do so from it. A unit test has been added that
modifies the filesystem between scans to test it.
Update Dependency scanner so it can scan the dependency of a TU with
a provided buffer rather than relying on the on disk file system to
provide the input file.
This makes it possible to pass "-o /dev/null" to `clang-scan-deps` and
skip some potentially expensive work, making timings less noisy. Also
removes the need for stream redirection.
Make it easier to control which optimizations are enabled by making
OptimizeArgs a bit masked enum. There's currently only one such
optimization, but more will be added in followup commits.
This patch adds new `-print-timing` option to `clang-scan-deps`. It measures the wall and process time taken to scan dependencies for the compilation database. This provides more representative data compared to measuring the timing for the whole tool invocation, since that includes parsing and generating JSON files, which can be significant for larger inputs.
Reviewed By: akyrtzi
Differential Revision: https://reviews.llvm.org/D147815
