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...
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.
Code Completion operates on a CompilerInstance that passes a primary
file down for type checking. This means it creates and registers
dependencies in the referenced name trackers. Despite the fact that
those dependencty edges are unused,
because the would-be swiftdeps file is never written to disk,
it is still a dependency source that should participate in the
request-based dependency tracking refactor.
Like the last commit, SourceFile is used a lot by Parse and Sema, but
less so by the ClangImporter and (de)Serialization. Split it out to
cut down on recompilation times when something changes.
This commit does /not/ split the implementation of SourceFile out of
Module.cpp, which is where most of it lives. That might also be a
reasonable change, but the reason I was reluctant to is because a
number of SourceFile members correspond to the entry points in
ModuleDecl. Someone else can pick this up later if they decide it's a
good idea.
No functionality change.
Most of AST, Parse, and Sema deal with FileUnits regularly, but SIL
and IRGen certainly don't. Split FileUnit out into its own header to
cut down on recompilation times when something changes.
No functionality change.
The build on Windows has been failing due to the ambiguous constructor
overload:
```
lib\Parse\ParseRequests.cpp(83): error C2666: 'swift::Parser::Parser': 2 overloads have similar conversions
include\swift\Parse\Parser.h(412): note: could be 'swift::Parser::Parser(std::unique_ptr<swift::Lexer,std::default_delete<_Ty>>,swift::SourceFile &,swift::SILParserTUStateBase *,swift::PersistentParserState *,std::shared_ptr<swift::SyntaxParseActions>,bool)'
with
[
_Ty=swift::Lexer
]
include\swift\Parse\Parser.h(408): note: or 'swift::Parser::Parser(unsigned int,swift::SourceFile &,swift::SILParserTUStateBase *,swift::PersistentParserState *,std::shared_ptr<swift::SyntaxParseActions>,bool)'
include\swift\Parse\Parser.h(403): note: or 'swift::Parser::Parser(unsigned int,swift::SourceFile &,swift::DiagnosticEngine *,swift::SILParserTUStateBase *,swift::PersistentParserState *,std::shared_ptr<swift::SyntaxParseActions>,bool)'
lib\Parse\ParseRequests.cpp(84): note: while trying to match the argument list '(unsigned int, swift::SourceFile, nullptr, nullptr, nullptr, bool)'
```
Rework the lazy function body parsing mechanism to use the
request-evaluator, so that asking for the body of a function will
initiate parsing. Clean up a number of callers to
AbstractFunctionDecl::getBody() that don't actually need the body, so
we don't perform unnecessary parsing.
This change does not delay parsing of function bodies in the general
case; rather, it sets up the infrastructure to always delay parsing of
function bodies.
Rework the lazy function body parsing mechanism to use the
request-evaluator, so that asking for the body of a function will
initiate parsing. Clean up a number of callers to
AbstractFunctionDecl::getBody() that don't actually need the body, so
we don't perform unnecessary parsing.
This change does not delay parsing of function bodies in the general
case; rather, it sets up the infrastructure to always delay parsing of
function bodies.
Lazy parsing for the members of nominal types and extensions depends
only on information already present in
`IterableDeclContext`. Eliminate the use of PersistentParserState as
an intermediary and have the member-parsing request construct a new
`Parser` instance itself to handle parsing. Make this possible even
for ill-formed nominal types/extensions to simplify the code path.
Eliminate `LazyMemberParser` and all of its uses, because it was only
present for lazy member parsing, which no longer needs it.
Ensure that lazy parsing of the members of nominal type definitions
and extensions is handled through a request. Most of the effort here
is in establishing a new request zone for parser requests.
