Today, loads and stores are treated as having @unowned(unsafe) ownership
semantics. This leaves the user to specify ownership changes on the loaded or
stored value independently of the load/store by inserting ARC operations. With
the change to Semantic SIL, this will no longer be true. Instead loads, stores
have ownership semantics that one must reason about such as copy, take, and
trivial.
This change moves us closer to that world by eliminating the default
OwnershipQualification argument from create{Load,Store}. This means that the
compiler developer cannot ignore reasoning about the ownership semantics of the
memory operation that they are creating.
Operationally, this is a NFC change since I have just gone through the compiler
and updated all places where we create loads, stores to pass in the former
default argument ({Load,Store}OwnershipQualifier::Unqualified), to
SILBuilder::create{Load,Store}(...). For now, one can just do that in situations
where one needs to create loads/stores, but over time, I am going to tighten the
semantics up via the verifier.
rdar://28685236
id-as-Any lets you pass Optional to an ObjC API that takes `nonnull id`, and also lets you bridge containers of `Optional` to `NSArray` etc. When this occurs, we can unwrap the value and bridge it so that inhabited optionals still pass into ObjC in the expected way, but we need something to represent `none` other than the `nil` pointer. Cocoa provides `NSNull` as the canonical "null for containers" object, which is the least bad of many possible answers. If we happen to have the rare nested optional `T??`, there is no precedented analog for these in Cocoa, so just generate a unique sentinel object to preserve the `nil`-ness depth so we at least don't lose information round-tripping across the ObjC-Swift bridge.
Making Optional conform to _ObjectiveCBridgeable is more or less enough to make this all work, though there are a few additional edge case things that need to be fixed up. We don't want to accept `AnyObject??` as an @objc-compatible type, so special-case Optional in `getForeignRepresentable`.
Implements SR-0140 (rdar://problem/27905315).
The new instructions are: ref_tail_addr, tail_addr and a new attribute [ tail_elems ] for alloc_ref.
For details see docs/SIL.rst
As these new instructions are not generated so far, this is a NFC.
id-as-Any lets you pass Optional to an ObjC API that takes `nonnull id`, and also lets you bridge containers of `Optional` to `NSArray` etc. When this occurs, we can unwrap the value and bridge it so that inhabited optionals still pass into ObjC in the expected way, but we need something to represent `none` other than the `nil` pointer. Cocoa provides `NSNull` as the canonical "null for containers" object, which is the least bad of many possible answers. If we happen to have the rare nested optional `T??`, there is no precedented analog for these in Cocoa, so just generate a unique sentinel object to preserve the `nil`-ness depth so we at least don't lose information round-tripping across the ObjC-Swift bridge.
Making Optional conform to _ObjectiveCBridgeable is more or less enough to make this all work, though there are a few additional edge case things that need to be fixed up. We don't want to accept `AnyObject??` as an @objc-compatible type, so special-case Optional in `getForeignRepresentable`.
Implements SR-0140 (rdar://problem/27905315).
The new instructions are: ref_tail_addr, tail_addr and a new attribute [ tail_elems ] for alloc_ref.
For details see docs/SIL.rst
As these new instructions are not generated so far, this is a NFC.
Simplify e.g., ASTContext::getBridgedToObjC(), which no longer needs
the optional return.
Eliminate the now-unused constraint kind for checking bridging to
Objective-C.
This establishes a real def-use relation from the self-parameter to any instruction which uses the dynamic-self type.
This is an addition to what was already done for opened archetypes.
The biggest part of this commit is to rename "OpenedArchetypeOperands" to "TypeDependentOperands" as this name is now more appropriate.
Other than that the change includes:
*) type-dependent operands are now printed after a SIL instruction in a comment as "type-defs:" (for debugging)
*) FuncationSignatureOpts doesn't need to explicitly check if a function doesn't bind dynamic self to remove a dead self metadata argument
*) the check if a function binds dynamic self (used in the inliner) is much simpler now
*) also collect type-dependent operands for ApplyInstBase::SubstCalleeType and not only in the substitution list
*) with this SILInstruction::mayHaveOpenedArchetypeOperands (used in CSE) is not needed anymore and removed
*) add type dependent operands to dynamic_method instruction
Regarding the generated code it should be a NFC.
*) cast optimizer: when a bridging cast is replaced with a function call and the owning convention of the instruction and the call parameter do not match, compensating retain/release instructions must be inserted.
*) cast optimizer: when a consuming dead cast instruction is removed a compensating release instruction must be inserted
*) mem2reg: An alloc_stack location which contains a destroy_addr must not be considered as a write-only location. The destroy_addr must be preserved.
rdar://problem/27601057
One minor revision: this lifts the proposed restriction against
overriding a non-open method with an open one. On reflection,
that was inconsistent with the existing rule permitting non-public
methods to be overridden with public ones. The restriction on
subclassing a non-open class with an open class remains, and is
in fact consistent with the existing access rule.
Previously it assumed that if we succeed in looking up the method in the current
module we must be able to request a definition (vs a declaration).
This is not true. It could be that we had declared the type in a different
module. Always ask for a declaration.
rdar://27547957
'fileprivate' is considered a broader level of access than 'private',
but for now both of them are still available to the entire file. This
is intended as a migration aid.
One interesting fallout of the "access scope" model described in
758cf64 is that something declared 'private' at file scope is actually
treated as 'fileprivate' for diagnostic purposes. This is something
we can fix later, once the full model is in place. (It's not really
/wrong/ in that they have identical behavior, but diagnostics still
shouldn't refer to a type explicitly declared 'private' as
'fileprivate'.)
As a note, ValueDecl::getEffectiveAccess will always return 'FilePrivate'
rather than 'Private'; for purposes of optimization and code generation,
we should never try to distinguish these two cases.
This should have essentially no effect on code that's /not/ using
'fileprivate' other than altered diagnostics.
Progress on SE-0025 ('fileprivate' and 'private')
Introduce bridging of NSError to ErrorProtocol, so an Objective-C API
expressed via an "NSError *" will be imported using ErrorProtocol in
the Swift. For example, the Objective-C method:
- (void)handleError:(NSError *)error userInteractionPermitted:(BOOL)userInteractionPermitted;
will now be imported as:
func handleError(_ error: ErrorProtocol, userInteractionPermitted: Bool)
This is bullet (3) under the proposed solution of SE-0112. Note that
we made one semantic change here: instead of removing the conformance
of NSError to ErrorProtocol, which caused numerous problems both
theoretical and actual because the model expects that an NSError
conforms to ErrorProtocol without requiring wrapping, we instead limit
the ErrorProtocol -> NSError conversion that would be implied by
bridging. This is defensible in the short term because it also
eliminates the implicit conversion, and aligns with SE-0072, which
eliminates implicit bridging conversions altogether.
Formerly SILGen would never emit this sequence. In fact in most places
we lower away dynamic Self, replacing it with the concrete Self type
instead.
However, with an upcoming change, I'm using 'metatype $Self' as a handy
way to grab IRGenSILFunction::LocalSelfMetadata, since that's what it
already does.
Note that the tests for this are in the next patch.
It is a hint to the optimizer that the code, where this builtin is called, is on the fast path.
Specifically, the inliner takes it into account and increases the assumed benefit for code where the builtin is located.
Compared to the fastPath/slowPath builtins, this builtin can be placed into plain linear code and doesn't need to be used in conditions.
Compared to the @inline(__always) attribute, this builtin has also an effect on the caller function. Let's assume
foo() calls bar() contains onFastPath
and both foo and bar are small functions. Then if bar gets inlined into foo, the builtin also increases the chances that foo gets inlined.
This would not be the case if @inline(__always) is used just for bar.
