When generic metadata for a class is requested in the same module where
the class is defined, rather than a call to the generic metadata
accessor or to a variant of typeForMangledNode, a call to a new
accessor--a canonical specialized generic metadata accessor--is emitted.
The new function is defined schematically as follows:
MetadataResponse `canonical specialized metadata accessor for C<K>`(MetadataRequest request) {
(void)`canonical specialized metadata accessor for superclass(C<K>)`(::Complete)
(void)`canonical specialized metadata accessor for generic_argument_class(C<K>, 1)`(::Complete)
...
(void)`canonical specialized metadata accessor for generic_argument_class(C<K>, count)`(::Complete)
auto *metadata = objc_opt_self(`canonical specialized metadata for C<K>`);
return {metadata, MetadataState::Complete};
}
where generic_argument_class(C<K>, N) denotes the Nth generic argument
which is both (1) itself a specialized generic type and is also (2) a
class. These calls to the specialized metadata accessors for these
related types ensure that all generic class types are registered with
the Objective-C runtime.
To enable these new canonical specialized generic metadata accessors,
metadata for generic classes is prespecialized as needed. So are the
metaclasses and the corresponding rodata.
Previously, the lazy objc naming hook was registered during process
execution when the first generic class metadata was instantiated. Since
that instantiation may occur "before process launch" (i.e. if the
generic metadata is prespecialized), the lazy naming hook is now
installed at process launch.
Clang provides options to override that default value.
These options are accessible via the -Xcc flag.
Some Swift functions explicitly disable the frame pointer.
The clang options will not override those.
The Objective-C runtime expects a signed pointer here. The existing test
would have caught this, except it was always disabled because the
symbol name passed to the dlsym() check should not have had the leading
'_'.
Fixes <rdar://problem/57679510>.
swift::GeneratedModule encapsulates an llvm::Module, llvm::LLVMContext
pair that must live and die together. It has convenient accessors for
projecting the module and context components. The meat of this type is
the two conversion functions, which transfer ownership of either the
module component to the caller or the module and context to ORCJIT.
This is because ORC enforces an ownership contract that is distinct from
LLVM's rather wild ownership story for modules and their associated
contexts. See http://llvm.org/docs/ORCv2.html#how-to-use-threadsafemodule-and-threadsafecontext
`SynthesizedFileUnit` is a container for synthesized declarations. Currently, it
only supports module-level declarations.
It is used by the SIL differentiation transform, which generates implicit struct
and enum declarations.
Without whole module optimization, the metadata accessors are emitted on
a per-file basis. The result is that if the file containing a generic
type is processed before the file containing a usage of that type that
would result in that prespecialization, the metadata accessor would have
already been emitted by the time that the usage is noted, making it
impossible for the newly created prespecialization to be returned from
the already-emitted metadata accessor.
Here, require that either whole module optimization is enabled so that
the metadata accessors are all emitted at once at the end, or else that
the usage of the prespecialization is in the same file as the type is
declared.
This adds code that can be used to build recursive type layouts. And
code that generates value witness IR based on the recursive type
layouts.
Value witnesses generated based on type layouts will only refer to
archetypes when computing fields offsets for frozen generic types (vs
instantiated type medata).
rdar://51988441
SIL differentiability witnesses are a new top-level SIL construct mapping
an "original" SIL function and derivative configuration to derivative SIL
functions.
This patch adds `SILDifferentiabilityWitness` IRGen.
`SILDifferentiabilityWitness` has a fixed `{ i8*, i8* }` layout:
JVP and VJP derivative function pointers.
Resolves TF-1146.
This was being done at an odd point in the frontend presumably because by that point the private discriminator had been fully computed. Instead, push the conditions for generating the prefix data down to debug info generation and stop mutating IRGenOptions::DebugFlag in the frontend.
Metadata accessors are dependent on prespecializations of the metadata
of generic, in-module types. Those prespecializations are themselves
dependent on usages of the types in functions. Consequently, the
accessors must be emitted after all the functions are emitted.
Prespecialized records contain direct references to the generic
arguments and protocol witnesses with which it is specialized for now.
Both prespecialized records and the records that are specialized at
runtime gain a trailing pointer-sized flagset. For now, the flags in it
include whether the record was prespecialized and whether it was known
to be canonical at compile time (which is true for prespecialized
records within the module which defines the type whose metadata is
specialized since in those cases the metadata accessor can be modified).
rdar://problem/56960307
Added worklist of prespecializations awaiting lazy emission to
IRGenModule. Added map from type decl to list of bound types for which
prespecializations will be emitted.
For now, no specializations are emitted.
Compatibility with earlier swift runtimes would require modifying the
runtime compatibility libraries to adjust the behavior of
checkMetadataState by way of typeForMangledNode or even
typeForMangledName. For now, simply require that a version of swift
whose runtime knows about prespecialized metadata is being targeted.
Associated type witnesses were not getting canonicalized with respect to
their appropriate generic signatures, causing types to be emitted into
the metadata that could not be properly demangled. Be consistent about
providing a generic signature for canonicalization.
Fixes SR-11642 / rdar://problem/56466693.
All the context dependencies in SIL type lowering have been eradicated, but IRGen's
type info lowering is still context-dependent and doesn't systemically pass generic
contexts around. Sink GenericContextScope bookkeeping entirely into IRGen for now.
https://forums.swift.org/t/improving-the-representation-of-polymorphic-interfaces-in-sil-with-substituted-function-types/29711
This prepares SIL to be able to more accurately preserve the calling convention of
polymorphic generic interfaces by letting the type system represent "substituted function types".
We add a couple of fields to SILFunctionType to support this:
- A substitution map, accessed by `getSubstitutions()`, which maps the generic signature
of the function to its concrete implementation. This will allow, for instance, a protocol
witness for a requirement of type `<Self: P> (Self, ...) -> ...` for a concrete conforming
type `Foo` to express its type as `<Self: P> (Self, ...) -> ... for <Foo>`, preserving the relation
to the protocol interface without relying on the pile of hacks that is the `witness_method`
protocol.
- A bool for whether the generic signature of the function is "implied" by the substitutions.
If true, the generic signature isn't really part of the calling convention of the function.
This will allow closure types to distinguish a closure being passed to a generic function, like
`<T, U> in (*T, *U) -> T for <Int, String>`, from the concrete type `(*Int, *String) -> Int`,
which will make it easier for us to differentiate the representation of those as types, for
instance by giving them different pointer authentication discriminators to harden arm64e
code.
This patch is currently NFC, it just introduces the new APIs and takes a first pass at updating
code to use them. Much more work will need to be done once we start exercising these new
fields.
This does bifurcate some existing APIs:
- SILFunctionType now has two accessors to get its generic signature.
`getSubstGenericSignature` gets the generic signature that is used to apply its
substitution map, if any. `getInvocationGenericSignature` gets the generic signature
used to invoke the function at apply sites. These differ if the generic signature is
implied.
- SILParameterInfo and SILResultInfo values carry the unsubstituted types of the parameters
and results of the function. They now have two APIs to get that type. `getInterfaceType`
returns the unsubstituted type of the generic interface, and
`getArgumentType`/`getReturnValueType` produce the substituted type that is used at
apply sites.
Structurally prevent a number of common anti-patterns involving generic
signatures by separating the interface into GenericSignature and the
implementation into GenericSignatureBase. In particular, this allows
the comparison operators to be deleted which forces callers to
canonicalize the signature or ask to compare pointers explicitly.
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 uniquing key for these was just the number of witness tables,
but the function itself referenced the specific existential type
it was instantiated with.
Everything still worked because getOrCreateHelperFunction() would
bitcast an existing function to the correct type, and in practice
the layout of an existential type only depends on the number of
witness tables.
However on master-next, other changes were made that stripped
off the bitcasts. This would result in assertions or LLVM
verifier failures when multiple existential types were used in
a single translation unit.
Fixes <rdar://problem/54780404>.
box descriptors
We want to substitute opaque result types in addTypeRef but when we pass
SILFunctionTypes this would fail because AST type substitution does not
support lowered SIL types.
Instead add addLoweredTypeRef which substitutes based on SILTypes.
rdar://54529445
If we're allowed to know at IRGen time what the underlying type of an opaque type is, we can
satisfy references to the opaque type's metadata or protocol witness tables by directly referencing
the underlying type instead.
When we generate code that asks for complete metadata for a fully concrete specific type that
doesn't have trivial metadata access, like `(Int, String)` or `[String: [Any]]`,
generate a cache variable that points to a mangled name, and use a common accessor function
that turns that cache variable into a pointer to the instantiated metadata. This saves a bunch
of code size, and should have minimal runtime impact, since the demangling of any string only
has to happen once.
This mostly just works, though it exposed a couple of issues:
- Mangling a type ref including objc protocols didn't cause the objc protocol record to get
instantiated. Fixed as part of this patch.
- The runtime type demangler doesn't correctly handle retroactive conformances. If there are
multiple retroactive conformances in a process at runtime, then even though the mangled string
refers to a specific conformance, the runtime still just picks one without listening to the
mangler. This is left to fix later, rdar://problem/53828345.
There is some more follow-up work that we can do to further improve the gains:
- We could improve the runtime-provided entry points, adding versions that don't require size
to be cached, and which can handle arbitrary metadata requests. This would allow for mangled
names to also be used for incomplete metadata accesses and improve code size of some generic
type accessors. However, we'd only be able to take advantage of the new entry points in
OSes that ship a new runtime.
- We could choose to always symbolic reference all type references, which would generally reduce
the size of mangled strings, as well as make runtime demangling more efficient, since it wouldn't
need to hit the runtime caches. This would however require that we be able to handle symbolic
references across files in the MetadataReader in order to avoid regressing remote mirror
functionality.
When referencing a superclass type from a subclass, for example, the
type uses the subclass's generic parameters, not the superclass's.
This can be important if a nested type constrains away some of its
parent type's generic parameters.
This doesn't solve all the problems around mis-referenced generic
parameters when some are constrained away, though. That might
require a runtime change. See the FIXME comments in the test cases.
rdar://problem/51627403
Instead of a thunk insert the dispatch into the original function.
If the original function should be executed the prolog just jumps to the "real" code in the function. Otherwise the replacement function is called.
There is one little complication here: when the replacement function calls the original function, the original function should not dispatch to the replacement again.
To pass this information, we use a flag in thread local storage.
The setting and reading of the flag is done in two new runtime functions.
rdar://problem/51043781
- In Sema, don't traverse nested declarations while deducing the opaque return type. This would
cause returns inside nested functions to clobber the return type of the outer function.
- In IRGen, walk the list of opaque return types we keep in the SourceFile already for type
reconstruction, instead of trying to visit them ad-hoc as part of walking the AST, since
IRGen doesn't normally walk the bodies of function decls directly.
Fixes rdar://problem/50459091
