Emit a once token when adding canonical prespecialized metadata records
to a nominal type descriptor and add the token itself as a trailing
object to the type descriptor. The new token will, in subsequent
commits, enable the canonical prespecialized metadata records attached
to the type descriptor to be added to the metadata cache exactly once.
When a generic type from a different module is not resilient within the
current module and at least one of its arguments is from the current
module, emit a non-canonical prespecialized record, and access that
metadata via a call to swift_getCanonicalSpecializedMetadata, passing in
the non-canonical record.
rdar://problem/56996727
rdar://problem/56997022
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.
MSVC does not realize that the switch is exhaustive and requires that
the path is explicitly marked as unreachable. This silences the C4715
warning ("not all control paths return a value").
It looks like the only thing that fails is the linkage computation
for the dynamic replacement key of class methods. Even though
methods have hidden linkage to prevent them from being directly
referenced from outside a resilient module, we need to ensure
the dynamic replacement key is visible.
Fixes <rdar://problem/58457716>.
This slightly regresses the standard library build (intentionally) while
generally improving the build of dispatch, foundation, xctest.
Rather than continuing to rely on the short-term hack of special casing
the standard library, identify the module where the decl originates
from. If the module is the current module, then assume that the symbol
need not be imported (static linking does not currently work on Windows
anyways). This allows for properly identifying the module where the
symbol will be homed.
Because we no longer special case the standard library here, a few known
metadata types will be incorrectly marked as being imported rather than
local.
Since linked entities which have `Shared` SILLinkage should be module
local, special case them to always be local. Without this the metadata
access function is still marked incorrectly.
With this computation we now get nearly all the cases correct. Dispatch
no longer has to rely on the linker relaxing the import to a local
binding. XCTest is also clean. Foundation misses the following case:
- `$sSS10FoundationE19_bridgeToObjectiveCAA8NSStringCyF`
The regressed cases in swiftCore are:
- `$sBi64_WV`
- `$sBi8_WV`
- `$sBi16_WV`
- `$sBi32_WV`
- `$sBpWV`
- `$syycWV`
- `$sBoWV`
- `$sBOWV`
- `$sBbWV`
- `$sytWV`
This seems unused currently, as attempting to query the DeclContext of
these types results in an immediate assertion that the kind of entity is
invalid. These are non-root protocol conformances, use
`getProtocolConformance` instead of the copy-paste value of
`getRootProtocolConformance`.
Prespecialized metadata may be requested in multiple modules and those
definitions must be deduplicated when statically linking those modules
together.
Here, the SILLinkage for prespecialized metadata is specified to be
Shared. Consequently, the IRLinkage's Linkage for this record is made
to be LinkOnceODRLinkage.
rdar://problem/56997414
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.
The weak imported flag is now only set if the attribute is unconditionally
weak linked, which is the case when it or one of its parent contexts has a
@_weakLinked attribute.
To correctly handle weak linking based availability with serialized SIL
functions, we need to serialize the actual version tuple when the SIL function
was introduced. This is because the deployment target of the client app can
be older than the deployment target that the original module was built with.
Fixes <rdar://problem/52783668>.
First, remove the AvailabilityContext parameter; it was confusing because
we actually always want to use the deployment target here.
Then, split this method up into three methods:
- isAlwaysWeakImported(): simply checks for a @_weakLinked attribute, either
on the declaration itself or one of its parent contexts.
- getAvailabilityForLinkage(): returns the OS version availability when
this declaration was introduced, or if the declaration does not have
explicit availability, check it's storage (if its an accessor), or its
parent contexts.
- isWeakImported(ModuleDecl *fromModule): combines these two checks to
determine if the declaration should be weak linked when referenced from
the given module, or if it might be weak referenced from some module
(if the module parameter is null).
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.
Since the return value of getAccessor() depends on mutable state, it
does not make sense in the request evaluator world. Let's begin by
removing some utility methods derived from getAccessor(), replacing
calls to them with calls to getAccessor().
This was done even for non-public inits because subclasses would always
override the base class's designated initializers, even if they were
inaccessible.
This is an ABI break, however in practice the only affected class
initializer was ManagedBuffer.init(_doNotCallMe:()), and we can just
make it @usableFromInline.
They aren't normally decl contexts, but if one has an opaque type, we want to be able to record
the property as a context so that we can reconstruct it in RemoteAST.
When Swift always copied the overlay dylibs into app bundles, it was OK
for these symbol references to be non-weak, but with the overlays now
part of the OS on Apple platforms, we need to handle backward deployment
scenarios where a new overlay does not exist on an old OS version.
A weak reference will serve to pull in the overlay dylib if it exists,
without causing a fatal error if it does not. rdar://problem/50110036
This is to support dynamic function replacement of functions with opaque
result type.
This approach requires that all state is thrown away (that could contain the
old returned type for an opaque type) between replacements.
rdar://48887938
Instead of a wholly separate lazyness mechanism for foreign metadata where
the first call to getAddrOfForeignTypeMetadataCandidate() would emit the
metadata, emit it using the lazy metadata mechanism.
This eliminates some code duplication. It also ensures that foreign
metadata is only emitted once per SIL module, and not once per LLVM
module, avoiding duplicate copies that must be ODR'd away in multi-threaded
mode.
This fixes the test case from <rdar://problem/49710077>.
In LLDB expressions, references to private metadata accessors may be
emitted and need to be bound to symbols available in the attached
program, even if these symbols are only supposed to have private
visibility within the program.
Also rdar://problem/48018240
To correctly call designated super class initializers the designated
intializer (and not the allocator) is dynamically replaceable.
Convenience allocators are dynamically replaceable as before.
Create two new semantic names: `ExternalImport` and `ExternalExport`.
These are for symbols which are either imported from an external module
or exported for consumption by external modules.
This is essentially a long-belated follow-up to Arnold's #12606.
The key observation here is that the enum-tag-single-payload witnesses
are strictly more powerful than the XI witnesses: you can simulate
the XI witnesses by using an extra case count that's <= the XI count.
Of course the result is less efficient than the XI witnesses, but
that's less important than overall code size, and we can work on
fast-paths for that.
The extra inhabitant count is stored in a 32-bit field (always present)
following the ValueWitnessFlags, which now occupy a fixed 32 bits.
This inflates non-XI VWTs on 32-bit targets by a word, but the net effect
on XI VWTs is to shrink them by two words, which is likely to be the
more important change. Also, being able to access the XI count directly
should be a nice win.
Now that we're never relatively addressing an Objective-C class reference,
stop emitting them as file-local (by eliminating the \01l_ prefix). This
is both a minor optimization and also a way to ensure that things will
break more consistently if a problem remains.
Start emitting associated conformance requirement descriptors for
inherited protocols, so we have a symbol to reference from resilient
witness tables and mangled names in the future.
