ProtocolConformanceRef already has an invalid state. Drop all of the
uses of Optional<ProtocolConformanceRef> and just use
ProtocolConformanceRef::forInvalid() to represent it. Mechanically
translate all of the callers and callsites to use this new
representation.
This memoizes the result, which is fine for all callers; the only
exception is open existential types where each new open existential
now explicitly gets a unique generic environment, allocated by
calling GenericEnvironment::getIncomplete().
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.
Asking for the layout of the interface type apparently gives the wrong answer,
causing key paths to access stored properties of generic classes using the wrong
strategy.
Fixes SR-10167 | rdar://problem/49230751.
This ensures that the trivial property descriptors is externally
accessible on targets like Windows which does not export symbols by
default. Thanks to Joe Groff for the pointer about the global aliases
for trivial property descriptors!
If a key path literal appears in a generic context with an existing context descriptor, this will allow us to
save some code size by not having to emit a separate GenericEnvironment descriptor.
This can happen when emitting an inlinable function in a resilient
module, because inlinable functions use the most conservative
access pattern.
This allows some earlier tests for keypaths inside inlinable
functions to pass IR emission, too.
An existing test used an external reference within the same module
to test external references; move this part to a separate test that
builds a separate module to correctly test this functionality.
Always use mangled type names to represent type metadata in keypath patterns.
For generic types, use the generic environment to pull substituted types
from the instantiation arguments.
Finishes the type metadata part of rdar://problem/38038799.
Extend the key-path pattern with a representation of the generic environment
of the key-path, which includes the generic parameters and generic
requirements of the environment.
When we emit "false" symbolic references to accesors for conformances or
type metadata, ensure that we end up with two-byte-aligned symbolic
references. This addresses a problem with ARM+Thumb compilation where the
low bit wasn't getting set for Thumb code.
Fixes rdar://problem/46067353.
When a type in keypath metadata is non-dependent, use a mangled type name
rather than a symbolic reference to an accessor function.
Part of rdar://problem/38038799.
Switch key path metadata over to mangled names for each of the places it
refers to either a type metadata accessor or a witness table accessor. For
now, the mangled name is a symbolic reference to the existing accessors.
Part of rdar://problem/38038799.
We were emitting relative references to entities that might be in
another translation unit. Use a GOT entry or thunk where appropriate.
Fixes <rdar://problem/45901706>.
Dynamic replacements are currently written in extensions as
extension ExtendedType {
@_dynamicReplacement(for: replacedFun())
func replacement() { }
}
The runtime implementation allows an implementation in the future where
dynamic replacements are gather in a scope and can be dynamically
enabled and disabled.
For example:
dynamic_extension_scope CollectionOfReplacements {
extension ExtentedType {
func replacedFun() {}
}
extension ExtentedType2 {
func replacedFun() {}
}
}
CollectionOfReplacements.enable()
CollectionOfReplacements.disable()
Use relative references instead of pointers so that the pattern can be true-const. Instead of trying
to instantiate a constant key path literal in-place, point to a cache variable that we can store
a pointer to the shared instance into when instantiated. Now that the pattern format has diverged
significantly from the instance format, simplify and refactor the instantiation code using a walker
for the pattern format instead of trying to reuse the code for working with instantiated instances.
rdar://problem/42674576
If we know a key path component can be accessed as a stored property, then we should also know whether it's a `let` or not, so it should be safe to encode this in the key path pattern. Stage this change in by changing the number of bits used to store in-line offsets, fixing up the parts of the key path implementation that assumed that it took up the entire payload bitfield.
Certain uses of protocols only formally need the requirement
signature, not any of the method requirements. This results in IRGen
seeing a protocol where none of the members have been validated except
the associated types. Account for this by allowing ProtocolInfo to
only contain the layout for the base protocols and associated types,
if requested.
Note that this relies on the layout of a witness table always putting
the "requirement signature part" at the front, or at least at offsets
that aren't affected by function requirements.
rdar://problem/43260117
When emitting fixed class metadata, we emit field offsets for all fields,
including those from superclasses, if any.
Get the ClassLayout for the correct class before looking up a field that
might potentially belong to a superclass. Soon, I'm going to slim down
ClassLayout instances to only store the fields belonging to the class
itself, removing the InheritedStoredProperites array altogether.
