Make sure we mangle opaque types using the same settings as the
debugger mangling (with OptimizeProtocolNames = false) to ensure
that we can reconstruct those names again.
Make `SynthesizedFileUnit` attached to a `SourceFile`. This seemed like the
least ad-hoc approach to avoid doing unnecessary work for other `FileUnit`s.
TBDGen: when visiting a `SourceFile`, also visit its `SynthesizedFileUnit` if
it exists.
Serialization: do not treat `SynthesizedFileUnit` declarations as xrefs when
serializing the companion `SourceFile`.
Resolves TF-1239: AutoDiff test failures.
Start fixing SR-12526: `@derivative` attribute cross-module deserialization
crash. Remove original `AbstractFunctionDecl *` from `DerivativeAttr` and store
`DeclID` instead, mimicking `DynamicReplacementAttr`.
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
Serialize derivative function configurations per module.
`@differentiable` and `@derivative` attributes register derivatives for
`AbstractFunctionDecl`s for a particular "derivative function configuration":
parameter indices and dervative generic signature.
To find `@derivative` functions registered in other Swift modules, derivative
function configurations must be serialized per module. When configurations for
a `AbstractFunctionDecl` are requested, all configurations from imported
modules are deserialized. This module serialization technique has precedent: it
is used for protocol conformances (e.g. extension declarations for a nominal
type) and Obj-C members for a class type.
Add `AbstractFunctionDecl::getDerivativeFunctionConfigurations` entry point
for accessing derivative function configurations.
In the differentiation transform: use
`AbstractFunctionDecl::getDerivativeFunctionConfigurations` to implement
`findMinimalDerivativeConfiguration` for canonical derivative function
configuration lookup, replacing `getMinimalASTDifferentiableAttr`.
Resolves TF-1100.
Serialize "is linear?" flag, differentiability parameter indices, and
differentiability generic signature.
Deserialization has some ad-hoc logic for setting the original declaration and
parameter indices for `@differentiable` attributes because
`DeclDeserializer::deserializeDeclAttributes` does not have access to the
original declaration.
Resolves TF-836.
Delete `@differentiable` attribute `jvp:` and `vjp:` arguments for derivative
registration. `@derivative` attribute is now the canonical way to register
derivatives.
Resolves TF-1001.
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.
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.
Remove the option to switch off nested types tables. In a world where
re-entrant direct lookup will cause deserialization to fail (or worse),
disabling these tables will only lead to further instability in the
compiler.
As part of this, we have to change the type export rules to
prevent `@convention(c)` function types from being used in
exported interfaces if they aren't serializable. This is a
more conservative version of the original rule I had, which
was to import such function-pointer types as opaque pointers.
That rule would've completely prevented importing function-pointer
types defined in bridging headers and so simply doesn't work,
so we're left trying to catch the unsupportable cases
retroactively. This has the unfortunate consequence that we
can't necessarily serialize the internal state of the compiler,
but that was already true due to normal type uses of aggregate
types from bridging headers; if we can teach the compiler to
reliably serialize such types, we should be able to use the
same mechanisms for function types.
This PR doesn't flip the switch to use Clang function types
by default, so many of the clang-function-type-serialization
FIXMEs are still in place.
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>
The `@noDerivative` attribute marks the non-differentiability parameters of a
`@differentiable` function type. All parameters except those marked with
`@noDerivative` are differentiability parameters.
For example, `@differentiable (Float, @noDerivative Float) -> Float` is only
differentiable with respect to its first parameter.
The `@noDerivative` attribute is represented as a
`SILParameterDifferentiability` bit on `SILParameterInfo`.
Add round-trip serialization tests.
Resolves TF-872.
Motivation: `GenericSignatureImpl::getCanonicalSignature` crashes for
`GenericSignature` with underlying `nullptr`. This led to verbose workarounds
when computing `CanGenericSignature` from `GenericSignature`.
Solution: `GenericSignature::getCanonicalSignature` is a wrapper around
`GenericSignatureImpl::getCanonicalSignature` that returns the canonical
signature, or `nullptr` if the underlying pointer is `nullptr`.
Rewrite all verbose workarounds using `GenericSignature::getCanonicalSignature`.
