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
Modeling builtins as first-class function values doesn't really make sense because there's no real function value to emit, and modeling them this way complicates passes that work with builtins because they have to invent function types for builtin invocations. It's much more straightforward to have a single instruction that references the builtin by ID, along with the type information for the necessary values, type parameters, and results, so add a new "builtin" instruction that directly represents a builtin invocation. NFC yet.
Swift SVN r22690
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 necessary to be able to properly stash values with nontrivial lowerings, such as metatypes and functions, inside existential containers. Modify SILGen to lower values to the proper abstraction level before storing them in an existential container. Part of the fix for rdar://problem/18189508, though runtime problems still remain when trying to actually dynamicCast out a metatype from an Any container.
Swift SVN r21830
We want to be able to work around problems with non-failable
Objective-C initializers actually failing, which can happen when the
API audit data incorrectly marks an initializer as non-failable.
Swift SVN r21711
These instructions do a bitcast operation without stack traffic (at the SIL level). unchecked_trivial_bit_cast represents a conversion from a potentially nontrivial type to a trivial type, such as from a class reference to Int. unchecked_ref_bit_cast represents a conversion between types for which retain_value and release_value has equivalent effects when applied on the input or output values.
Swift SVN r19053
Add objc_metatype_to_object and objc_existential_metatype_to_object to convert metatypes to AnyObject, and objc_protocol to get a reference to an @objc protocol descriptor as a Protocol class instance.
Swift SVN r18824
put the result in a different place.
WIP: no IRGen support yet.
This will eventually be the required form when casting
to an address-only type; the existing instructions will
have only scalar outputs.
Swift SVN r18780
We now enforce via an assert that each witness table is unique and that
every protocol conformance that is referenceable from SIL must have a
witness table matched to it.
Also, I taught the linker that it should deserialize witness tables for
InitExistentialRefInst instructions, something that was missed before.
Swift SVN r17283
An unsafe cast from a base to a derived class isn't really all that different from one from Builtin.NativeObject to an arbitrary class, so relax this pair of instructions to allow an arbitrary bitcast. This only combines the instructions; it doesn't attempt to simplify any codegen that was emitting round-trip casts before yet.
Swift SVN r16736
This allows the payload for a loadable enum to be unsafely projected without branching, enabling more enum optimizations when switch branches can be culled or when indirect enum code can be promoted.
Swift SVN r16729
This was part of the original weak design that
there was never any particular reason to rush the
implementation for. It's convenient to do this now
so that we can use it to implement Unmanaged<T> for
importing CF types.
Swift SVN r16693
Give us a way to formally represent autoreleases in SIL separate from autoreleased returns, allowing us to lifetime-extend inner pointer parameters the lazy way and hopefully clean up some asmname hacks in the stdlib implementation too.
Swift SVN r16632
Add project_block_storage, to project the capture storage from within a block_storage, and init_block_storage_header, to represent filling out the block header.
Swift SVN r16358
These bits are orthogonal to each other, so combine them into one, and diagnose attempts to produce a type that's both. Spot-fix a bunch of places this revealed by inspection that we would have crashed in SILGen or IRGen if blocks were be handled.
Swift SVN r16088
Make ObjCMutablePointer @objc-able for (potentially optional) class types, and bridge it down to UnsafePointer when calling @objc entry points.
Swift SVN r15838
retain_value instructions, just like we do for strong_retain/release.
This wraps up rdar://15889208, which is admittedly more of a moral
victory than a practical one.
Swift SVN r15804
I am going to use this in a forth coming fix to the Specializer. The reason I
refactored it out into SILBuilder is this seems like generic useful
functionality.
rdar://16490450
Swift SVN r15745
