The client code doesn't actually call into these specialized functions even
though they have public linkage. This could lead to TBD verification failure
shown in rdar://44777994.
This patch also warns users' codebase when `export: true` is specified.
Type erasure requires a circular construction by its very nature:
@_typeEraser(AnyProto)
protocol Proto { /**/ }
public struct AnyProto : Proto {}
If we eagerly resolve AnyProto, the chain of resolution steps that
deserialization must make goes a little something like this:
Lookup(Proto)
-> Deserialize(@_typeEraser(AnyProto))
-> Lookup(AnyProto)
-> DeserializeInheritedStuff(AnyProto)
-> Lookup(Proto)
This cycle could be broken if the order of incremental inputs was
such that we had already cached the lookup of Proto.
Resolve this cycle in any case by suspending the deserialization of the
type eraser until the point it's demanded by adding
ResolveTypeEraserTypeRequest.
rdar://61270195
Remove logic for parsing and diagnosing `jvp:` and `vjp:` arguments for
`@differentiable` attribute. No logic remains for handling those arguments.
Follow-up to TF-1001.
Delete `@differentiable` attribute `jvp:` and `vjp:` arguments for derivative
registration. `@derivative` attribute is now the canonical way to register
derivatives.
Resolves TF-1001.
We were always dropping the error status when returning from parseExprImpl. We
were also incorrectly keeping error status after recovering by finding the
right close token in parseList. This change fixes both, and also updates a few
callers of parseList that assumed when they reported a failure parsing an
element the list as a whole would get error status, which isn't true due to
recovery.
In order to allow this, I've had to rework the syntax of substituted function types; what was previously spelled `<T> in () -> T for <X>` is now spelled `@substituted <T> () -> T for <X>`. I think this is a nice improvement for readability, but it did require me to churn a lot of test cases.
Distinguishing the substitutions has two chief advantages over the existing representation. First, the semantics seem quite a bit clearer at use points; the `implicit` bit was very subtle and not always obvious how to use. More importantly, it allows the expression of generic function types that must satisfy a particular generic abstraction pattern, which was otherwise impossible to express.
As an example of the latter, consider the following protocol conformance:
```
protocol P { func foo() }
struct A<T> : P { func foo() {} }
```
The lowered signature of `P.foo` is `<Self: P> (@in_guaranteed Self) -> ()`. Without this change, the lowered signature of `A.foo`'s witness would be `<T> (@in_guaranteed A<T>) -> ()`, which does not preserve information about the conformance substitution in any useful way. With this change, the lowered signature of this witness could be `<T> @substituted <Self: P> (@in_guaranteed Self) -> () for <A<T>>`, which nicely preserves the exact substitutions which relate the witness to the requirement.
When we adopt this, it will both obviate the need for the special witness-table conformance field in SILFunctionType and make it far simpler for the SILOptimizer to devirtualize witness methods. This patch does not actually take that step, however; it merely makes it possible to do so.
As another piece of unfinished business, while `SILFunctionType::substGenericArgs()` conceptually ought to simply set the given substitutions as the invocation substitutions, that would disturb a number of places that expect that method to produce an unsubstituted type. This patch only set invocation arguments when the generic type is a substituted type, which we currently never produce in type-lowering.
My plan is to start by producing substituted function types for accessors. Accessors are an important case because the coroutine continuation function is essentially an implicit component of the function type which the current substitution rules simply erase the intended abstraction of. They're also used in narrower ways that should exercise less of the optimizer.
Diagnose `@derivative` and `@transpose` attributes that are missing the
required comma before the `wrt:` clause:
```
@derivative(of: foo wrt: x)
@transpose(of: bar wrt: (x, y))
```
Previously, this was undiagnosed.
Resolves TF-1168.
If a CC token is right after the '{' we still don't know it's an implicit
getter or a start of a accessor block. Previously, the parser used to
parse it as an accessor block, but it prevents fast-completion kicks in.
Instead handle it as a part of function body parsing so the
fast-completion works.
rdar://problem/58851121
This will be used for compiler-driven type erasure for dynamic
replacement of functions with an opaque return type. For now, just
parse the attribute and ignore it.
Instead of interleaving typechecking and parsing
for SIL files, first parse the file for Swift
decls by skipping over any intermixed SIL decls.
Then we can perform type checking, and finally SIL
parsing where we now skip over Swift decls.
This is an intermediate step to requestifying the
parsing of a source file for its Swift decls.
Previously we would always return true if we
encountered a decl modifier keyword, however this
could cause us to incorrectly consider SIL's
usage of such keywords, e.g 'private', to be the
start of a Swift decl.
Adjust the logic to check the next token for the
start of a Swift decl.
SIL differentiability witnesses are a new top-level SIL construct mapping
"original" SIL functions to derivative SIL functions.
SIL differentiability witnesses have the following components:
- "Original" `SILFunction`.
- SIL linkage.
- Differentiability parameter indices (`IndexSubset`).
- Differentiability result indices (`IndexSubset`).
- Derivative `GenericSignature` representing differentiability generic
requirements (optional).
- JVP derivative `SILFunction` (optional).
- VJP derivative `SILFunction` (optional).
- "Is serialized?" bit.
This patch adds the `SILDifferentiabilityWitness` data structure, with
documentation, parsing, and printing.
Resolves TF-911.
Todos:
- TF-1136: upstream `SILDifferentiabilityWitness` serialization.
- TF-1137: upstream `SILDifferentiabilityWitness` verification.
- TF-1138: upstream `SILDifferentiabilityWitness` SILGen from
`@differentiable` and `@derivative` attributes.
- TF-20: robust mangling for `SILDifferentiabilityWitness` names.
The current way that VarDecl::isLazilyInitializedGlobal() is implemented does
not work in the debugger, since the DeclContext of all VarDecls are deserialized
Swift modules. By adding a bit to the VarDecl we can recover the fact that a
VarDecl was in fact a global even in the debugger.
<rdar://problem/58939370>
Store in `DifferentiableAttr` the original declaration on which the attribute
is declared.
The original declaration is resolved during parsing and deserialization
(not yet upstreamed).
Progress towards TF-828: upstream `@differentiable` attribute type-checking.
Rather than parsing all delayed bodies for
`-dump-parse` once we finish parsing, tell the
parser not to delay any bodies. This then allows
us to remove `DelayedDeclLists` from
PersistentParserState.
