A request is intended to be a pure function of its inputs. That function could, in theory, fail. In practice, there were basically no requests taking advantage of this ability - the few that were using it to explicitly detect cycles can just return reasonable defaults instead of forwarding the error on up the stack.
This is because cycles are checked by *the Evaluator*, and are unwound by the Evaluator.
Therefore, restore the idea that the evaluate functions are themselves pure, but keep the idea that *evaluation* of those requests may fail. This model enables the best of both worlds: we not only keep the evaluator flexible enough to handle future use cases like cancellation and diagnostic invalidation, but also request-based dependencies using the values computed at the evaluation points. These aforementioned use cases would use the llvm::Expected interface and the regular evaluation-point interface respectively.
Using std::string in the function signature copies the constant string
into a stack allocated copy, which is the one referenced by the
StringRef that DiagnosticInfo stores. when the stack is abandoned, the
string seems to be modificed in VC++, which makes the test fail in
Windows.
Using const char * in the signature avoids the std::string creation, and
StringRef will refer to the static data instead.
`AutoDiffIndexSubset` is a fixed-size bit vector that is used for efficiently representing a subset of indices in automatic differentiation, specifically for representing a subset of parameters and results of a function to differentiate with respect to. It is uniqued in `ASTContext`.
This patch adds definition and unit tests for `AutoDiffIndexSubset` along with new files `AutoDiff.h` and `AutoDiff.cpp` into the 'AST' target, with no changes to the compiler's behavior. More data structures used for AutoDiff will be added to these files.
----------------------------
This is part of the ongoing effort to merge the experimental [differentiable programming feature](https://forums.swift.org/t/differentiable-programming-mega-proposal/28547) (informally referred to as "AutoDiff") to the 'master' branch for code reviews and better maintenance.
Upstreaming task: [TF-879](https://bugs.swift.org/browse/TF-879)
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.
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.
Begin refactoring the request evaluator by swapping SWIFT_TYPEID for
SWIFT_REQUEST. Introduce the Zone of the request as a formal parameter
to the macro, then re-expand the request macro to get the type info
back.
SWIFT_REQUEST will eventually grow to encompass more information about
requests as we seek to reduce the boilerplate involved in their
definitions.
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances in the swift repo.
Encode the input and output parameters for a SimpleRequest instance in a
function type and move the CacheKind to the end, making it easier to
sort out inputs from outputs:
```
class DefaultTypeRequest
: public SimpleRequest<DefaultTypeRequest,
Type(KnownProtocolKind, const DeclContext *),
CacheKind::SeparatelyCached>
```
