This is a type that has ownership of a reference while allowing access to the
spare bits inside the pointer, but which can also safely hold an ObjC tagged pointer
reference (with no spare bits of course). It additionally blesses one
Foundation-coordinated bit with the meaning of "has swift refcounting" in order
to get a faster short-circuit to native refcounting. It supports the following
builtin operations:
- Builtin.castToBridgeObject<T>(ref: T, bits: Builtin.Word) ->
Builtin.BridgeObject
Creates a BridgeObject that contains the bitwise-OR of the bit patterns of
"ref" and "bits". It is the user's responsibility to ensure "bits" doesn't
interfere with the reference identity of the resulting value. In other words,
it is undefined behavior unless:
castReferenceFromBridgeObject(castToBridgeObject(ref, bits)) === ref
This means "bits" must be zero if "ref" is a tagged pointer. If "ref" is a real
object pointer, "bits" must not have any non-spare bits set (unless they're
already set in the pointer value). The native discriminator bit may only be set
if the object is Swift-refcounted.
- Builtin.castReferenceFromBridgeObject<T>(bo: Builtin.BridgeObject) -> T
Extracts the reference from a BridgeObject.
- Builtin.castBitPatternFromBridgeObject(bo: Builtin.BridgeObject) -> Builtin.Word
Presents the bit pattern of a BridgeObject as a Word.
BridgeObject's bits are set up as follows on the various platforms:
i386, armv7:
No ObjC tagged pointers
Swift native refcounting flag bit: 0x0000_0001
Other available spare bits: 0x0000_0002
x86_64:
Reserved for ObjC tagged pointers: 0x8000_0000_0000_0001
Swift native refcounting flag bit: 0x0000_0000_0000_0002
Other available spare bits: 0x7F00_0000_0000_0004
arm64:
Reserved for ObjC tagged pointers: 0x8000_0000_0000_0000
Swift native refcounting flag bit: 0x4000_0000_0000_0000
Other available spare bits: 0x3F00_0000_0000_0007
TODO: BridgeObject doesn't present any extra inhabitants. It ought to at least provide null as an extra inhabitant for Optional.
Swift SVN r22880
layouts. Introduce new SIL instructions to initialize
and open existential metatype values.
Don't actually, y'know, lift any of the restriction on
existential metatypes; just pointlessly burn extra
memory storing them.
Swift SVN r22592
This is controlled by a new isWholeModule() attribute in SILModule.
It gives about 9% code size reduction on the benchmark executables.
For test-suite reasons it is currently not done for the stdlib.
Swift SVN r22491
- A spot fix in SILGen for reabstracting the result of a downcast, which fixes checked casts to function types.
- Associate the layout information in type metadata records with the most abstract representation of the type. This is the correct thing to do in cases where we need the metadata as a tag for an opaque value--if we store a value in an Any, or pass it as an unconstrained generic parameter, we must maximally reabstract it. This fixes the value semantics of existentials containing trivial metatypes.
- To ensure that we get runtime layout of structs and enums correct when they contain reabstractable types, introduce a "metadata for layout" concept, which doesn't need to describe the canonical metadata for the type, but only needs to describe a type with equivalent layout and value semantics. This is a correctness fix that allows us to correctly lay out generic types containing dependent tuples and functions, and although we don't really take advantage of it here, it's also a potential runtime performance win down the road, because we could potentially produce direct metadata for a primitive type that's layout-equivalent with a runtime-instantiated type. To aid in type safety here, push SILType deeper into IRGen in places where we potentially care about specific representations of types.
- Finally, fix an inconsistency between the runtime and IRGen's concept of what spare bits unmanaged references and thick metatypes have.
Together, these fixes address rdar://problem/16406907, rdar://problem/17822208, rdar://problem/18189508, and likely many other related issues, and also fixes crash suite cases 012 and 024.
Swift SVN r21963
We were stopping too early when binding witness tables for local archetypes, causing us to miss binding witness tables for native protocols if the number of total protocols was greater than the number of protocols with witness tables, and we failed to increment the local type data key to match the Archetype::getConformsTo() ordinal when binding polymorphic parameters. Together these fix rdar://problem/18232916 (though adding any methods to a class still crashes because of rdar://problem/17480006).
Swift SVN r21796
instances of Swift subclasses of ObjC classes.
We were already doing this in the runtime. This patch
unhides the runtime's mask word (swift_isaMask) and makes
IR-gen take advantage of it when it can.
Swift SVN r21592
If a type has to be passed or returned resiliently, it
will necessarily be passed indirectly, which is already
represented in SILFunctionType. There is no need to
represent this as a separate channel of information.
NFC. Also fixes a problem where the signature cache
for ExtraData::Block was writing past the end of an
array (but into the storage for an adjacent array
which was fortunately never used).
ExtraData should also disappear as a concept, but we're
still relying on that for existential protocol witnesses.
Swift SVN r21548
pass the size and alignment of each field. Take advantage
of this to pass a constant size and alignment when
possible.
This avoids the need to recursively find type metadata for
every field type, allowing generic recursively-structured
classes to be built. There are a number of more complicated
cases that this approach isn't good enough for, but this
is good enough for now to fix rdar://18067671.
Also make an effort to properly support generic subclasses
of Objective-C classes.
Swift SVN r21506
refcounting and take advantage of it.
Also, set the Swift1 flag in classes we generate.
Also, initialize a global cache of the non-pointer-isa
mask and use that instead of object_getClass, at least
within the runtime.
Also, centralize the runtime on a _swift_getSuperclass
function and make that use a direct access while we
await word from Greg on the desired ABI requirements.
Swift SVN r21077
of a generic superclass.
A new generic class gets its metaclass's superclass pointer from the
superclass's metaclass. On arm64 the superclass's metaclass may not be
a pointer and must be fetched using object_getClass().
Three existing tests caught this bug but only when running on an iOS 8
device. On iOS 7, the arclite implementation of objc_readClassPair()
happened to rewrite the field before the runtime tripped over it.
Swift SVN r20811
unexpected forematter from the superclass.
This requires a pretty substantial shift in the
generic-metadata allocation/initialization dance
because (1) we can't allocate class metadata without
knowing what the superclass is and (2) the offset
from the metadata cache entry to the address point is
no longer determined solely by the metadata pattern.
While I'm making invasive changes to metadata, fix
two race conditions in metadata creation. The first
is that we need to ensure that only one thread succeeds
at lazily creating a generic-metadata cache. The second
is that we need to ensure that only one thread actually
attempts to create a particular metadata; any others
should block until the metadata is successfully built.
This commit finishes rdar://17776354. LLDB will
need to adjust to the runtime-private metadata layout
changes.
Swift SVN r20537
Expose Substitution's archetype, replacement, and conformances only through getters so we can actually assert invariants about them. To start, require replacement types to be materializable in order to catch cases where the type-checker tries to bind type variables to lvalue or inout types, and require the conformance array to match the number of protocol conformances required by the archetype. This exposes some latent bugs in the test suite I've marked as failures for now:
- test/Constraints/overload.swift was quietly suffering from <rdar://problem/17507421>, but we didn't notice because we never tried to codegen it.
- test/SIL/Parser/array_roundtrip.swift doesn't correctly roundtrip substitutions, which I filed as <rdar://problem/17781140>.
Swift SVN r20418
functions, and make those functions memoize the result.
This memoization can be both threadsafe and extremely
fast because of the memory ordering rules of the platforms
we're targeting: x86 is very permissive, and ARM has a
very convenient address-dependence rule which happens to
exactly match the semantics we need.
Swift SVN r20381
a flags field, add an instance address point field, and reserve
some additional space.
This change must be coordinated with a corresponding change
to ObjC runtime bits in libarclite; without this, dynamic
subclassing features like KVO will break.
The actual contents of the new fields can change without
bothering the ObjC runtime.
Swift SVN r20183
lldb needs this to be able to tell how many generic parameters are actually needed to instantiate a generic type. Fixes <rdar://problem/17425286>.
Swift SVN r19573
r210062 they can point at arbitrary ConstantExprs again, and as of
r210734 our use of this can actually pass the IR verifier again.
Patch by Justin Bogner.
Swift SVN r18834
Blocks need their own type metadata with value witnesses appropriate to the block representation. Fixes <rdar://problem/16918740> and <rdar://problem/16981126>.
Swift SVN r18508
At long last, our generic classes are legal ObjC citizens. Note that you'll need to be either on OSX 10.10, or on OSX 10.9 with a recent enough Xcode 6.0 to have a not-broken arclite (6A207 worksforme) and building against a OSX 10.10 SDK, for this to work going forward.
Swift SVN r17916
If we officially register our classes with the ObjC runtime, we can't get away with generic class instances sharing a runtime name or a metaclass anymore, so pack the metaclass and rodata templates into the generic metadata template and add codegen to the fill function to wire up the references at instantiation time. Since we don't have a runtime mangler yet, create a stupid unique name for classes by tacking on the pointer value.
Swift SVN r17882
This basically just means "it's a CF class" for now,
but you could imagine applying this to all sorts of
class-like types from peer runtimes that we can't
support all possible language features for.
There are quite a few language features that require
fairly deep object-model integration to implement,
like subclassing and adding polymorphic methods.
Some of those features, like final classes, are useful
to generally support as attributes, but most of
them aren't. At least in the short term, it makes
sense to have a big hammer we can hit things with.
Swift SVN r17428
I've put these fields on the class object for now, just
so we can at least theoretically update them. A superclass
that grew left rather than right could maybe even be made
to work with this schema, but probably not.
rdar://16705821
Swift SVN r16880
We really don't need to support individual objects
this large, much less more than 4 billion fields in
a single type.
Also rearrange the fields to bring the instance
size/alignment fields closer to the class header,
just for a minor locality win.
Swift SVN r16879
We can't know whether a mixed-heritage class has a non-pointer isa, so use object_getClass to get its isa pointer. Fixes <rdar://problem/16656489>.
Swift SVN r16549
Blocks need to be born on the stack, so we need a way to represent that on-stack storage. @block_storage T will represent the layout of a block that contains storage for a capture of type T.
Swift SVN r16355
We should never actually try to emit metadata for dependent types, lvalues, inouts, or SIL function types; these cases indicate upstream bugs in Sema or SILGen.
Swift SVN r16058
ObjC protocol descriptors are uniqued by the ObjC runtime and lazily emitted by Clang, so we shouldn't burn time eagerly emitting descriptors for every protocol in the universe. Addresses some of the performance issue in <rdar://problem/16520314>.
Swift SVN r15924
Create a global alias into the metadata of @objc-visible classes at their address point, which should make these classes visible for linking from ObjC, fixing <rdar://problem/14449644>.
Swift SVN r15921
Language features like erasing concrete metatype
values are also left for the future. Still, baby steps.
The singleton ordinary metatype for existential types
is still potentially useful; we allow it to be written
as P.Protocol.
I've been somewhat cavalier in making code accept
AnyMetatypeType instead of a more specific type, and
it's likely that a number of these places can and
should be more restrictive.
When T is an existential type, parse T.Type as an
ExistentialMetatypeType instead of a MetatypeType.
An existential metatype is the formal type
\exists t:P . (t.Type)
whereas the ordinary metatype is the formal type
(\exists t:P . t).Type
which is singleton. Our inability to express that
difference was leading to an ever-increasing cascade
of hacks where information is shadily passed behind
the scenes in order to make various operations with
static members of protocols work correctly.
This patch takes the first step towards fixing that
by splitting out existential metatypes and giving
them a pointer representation. Eventually, we will
need them to be able to carry protocol witness tables
Swift SVN r15716
Eventually, SILGen will need to do something like this, and it
should go in the sil_vtable, and we should base the IR vtable
on that information. For now, emitting multiple entries with
the same pointer in each is just bogus.
Swift SVN r15533
As part of the nominal type descriptor for a struct or class, build a function that lazily generates the vector of type metadata for the fields of the nominal type given an instantiation of the type's metadata. To cache this for nongeneric types, produce a global variable we can stash the result in, or for generic types, reserve some space in the metadata template so that generic metadata instantiation naturally provides a space for every instance of the type.
Reapplying now that the missing Float80 builtin metadata is available.
Swift SVN r15260
