Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
Rename the member on ASTLoweringDescriptor and
IRGenDescriptor to make it more explicit it returns
the files that need emitting, rather than just the
files that happen to be present. This distinction
will become important once we start emitting code
only for a specific set of symbols.
And also rename the underlying request and
descriptor.
This rename is motivated by the fact that the
operation may instead perform parsing of SIL files
and/or deserialization of SIB files.
Split off the notion of "recording" dependencies from the notion of
"collecting" dependencies. This corrects an oversight in the previous
design where dependency replay and recording were actually not "free" in
WMO where we actually never track dependencies. This architecture also
lays the groundwork for the removal of the referenced name trackers.
The algorithm builds upon the infrastructure for dependency sources and
sinks laid down during the cut over to request-based dependency tracking
in #30723.
The idea of the naive algorithm is this:
For a chain of requests A -> B* -> C -> D* -> ... -> L where L is a lookup
request and all starred requests are cached, once L writes into the
dependency collector, the active stack is walked and at each cache-point
the results of dependency collection are associated with the request
itself (in this example, B* and D* have all the names L found associated
with them). Subsequent evaluations of these cached requests (B* and D*
et al) will then *replay* the previous lookup results from L into the
active referenced name tracker. One complication is, suppose the
evaluation of a cached request involves multiple downstream name
lookups. More concretely, suppose we have the following request trace:
A* -> B -> L
|
-> C -> L
|
-> D -> L
|
-> ...
Then A* must see the union of the results of each L. If this reminds
anyone of a union-find, that is no accident! A persistent union-find
a la Conchon and Filliatre is probably in order to help bring down peak
heap usage...
They both do essentially the same thing, with the
single-file request being the single-element case
of the whole-module request, with only the call to
`getAllForModule` really caring about the
difference.
Define a new type DependencyCollector that abstracts over the
incremental dependency gathering logic. This will insulate the
request-based name tracking code from future work on private,
intransitive dependencies.
