This attribute indicates that the given SILFunction has to be
added to "accessible functions" section and could be looked up
at runtime using a special API.
This invalidation kind is used when a compute-effects pass changes function effects.
Also, let optimization passes which don't change effects only invalidate the `FunctionBody` and not `Everything`.
Previously, when attempting to pattern-match bridged ObjC properties,
there was an assertion about the location of destroy_value instructions
in the code that we were trying to match. Instead, bail in the face of
an unexpected pattern.
rdar://99873905
Andy some time ago already created the new API but didn't go through and update
the old occurences. I did that in this PR and then deprecated the old API. The
tree is clean, so I could just remove it, but I decided to be nicer to
downstream people by deprecating it first.
Previously, for the BridgedProperty pattern, there were two flavors of
outlined function that would be formed, varying on the ownership of the
instance whose field is being access:
(1) guaranteed_in -- for use by addresses
(2) unowned -- for use by values which were not destroyed until some
time after the pattern of interest is matched
Now that the lifetime of the instance may be shortened to just after the
call to the objc method, the latter of these is not appropriate for
values. We would have to re-extend the lifetime until after the method
returns.
Instead, here, we add a new variant
(3) owned -- for use by values which were destroyed just after the objc
method call
Doing so requires new mangling.
Thanks to CopyPropagation canonicalizing all values, not just those for
which there is a copy_value instruction, the lifetime of the value that
is loaded in the BridgedProperty pattern is shortened and the
destroy_value appears right after its use rather than after the full CFG
for the bridged property. Updated the BridgedProperty pattern to match
that newly hoisted instruction.
Previously, the match failed to find the larger sequence that began with
load [copy] and ended with destroy_value because the iterator advanced
after finding the load [copy]. Advanced the iterator here.
Enables reverting the test outlining test changes introduced in
a52b8966c6.
The main point of this change is to make sure that a shared function always has a body: both, in the optimizer pipeline and in the swiftmodule file.
This is important because the compiler always needs to emit code for a shared function. Shared functions cannot be referenced from outside the module.
In several corner cases we missed to maintain this invariant which resulted in unresolved-symbol linker errors.
As side-effect of this change we can drop the shared_external SIL linkage and the IsSerializable flag, which simplifies the serialization and linkage concept.
When an instruction is "deleted" from the SIL, it is put into the SILModule::scheduledForDeletion list.
The instructions in this list are eventually deleted for real in SILModule::flushDeletedInsts(), which is called by the pass manager after each pass run.
In other words: instruction deletion is deferred to the end of a pass.
This avoids dangling instruction pointers within the run of a pass and in analysis caches.
Note that the analysis invalidation mechanism ensures that analysis caches are invalidated before flushDeletedInsts().
... with a fix for a non-assert build crash: I used the wrong ilist type for SlabList. This does not explain the crash, though. What I think happened here is that llvm miscompiled and put the llvm_unreachable from the Slab's deleteNode function unconditionally into the SILModule destructor.
Now by using simple_ilist, there is no need for a deleteNode at all.
If we know that we have a FunctionRefInst (and not another variant of FunctionRefBaseInst), we know that getting the referenced function will not be null (in contrast to FunctionRefBaseInst::getReferencedFunctionOrNull).
NFC
Since the two ExtInfos share a common ClangTypeInfo, and C++ doesn't let us
forward declare nested classes, we need to hoist out AnyFunctionType::ExtInfo
and SILFunctionType::ExtInfo to the top-level.
We also add some convenience APIs on (AST|SIL)ExtInfo for frequently used
withXYZ methods. Note that all non-default construction still goes through the
builder's build() method.
We do not add any checks for invariants here; those will be added later.
If there is a release of the bridged value in between the bridge call
and the objective-c call we need to account for that and can't just use
a guaranteed convention.
rdar://61911131
In order to allow this, I've had to rework the syntax of substituted function types; what was previously spelled `<T> in () -> T for <X>` is now spelled `@substituted <T> () -> T for <X>`. I think this is a nice improvement for readability, but it did require me to churn a lot of test cases.
Distinguishing the substitutions has two chief advantages over the existing representation. First, the semantics seem quite a bit clearer at use points; the `implicit` bit was very subtle and not always obvious how to use. More importantly, it allows the expression of generic function types that must satisfy a particular generic abstraction pattern, which was otherwise impossible to express.
As an example of the latter, consider the following protocol conformance:
```
protocol P { func foo() }
struct A<T> : P { func foo() {} }
```
The lowered signature of `P.foo` is `<Self: P> (@in_guaranteed Self) -> ()`. Without this change, the lowered signature of `A.foo`'s witness would be `<T> (@in_guaranteed A<T>) -> ()`, which does not preserve information about the conformance substitution in any useful way. With this change, the lowered signature of this witness could be `<T> @substituted <Self: P> (@in_guaranteed Self) -> () for <A<T>>`, which nicely preserves the exact substitutions which relate the witness to the requirement.
When we adopt this, it will both obviate the need for the special witness-table conformance field in SILFunctionType and make it far simpler for the SILOptimizer to devirtualize witness methods. This patch does not actually take that step, however; it merely makes it possible to do so.
As another piece of unfinished business, while `SILFunctionType::substGenericArgs()` conceptually ought to simply set the given substitutions as the invocation substitutions, that would disturb a number of places that expect that method to produce an unsubstituted type. This patch only set invocation arguments when the generic type is a substituted type, which we currently never produce in type-lowering.
My plan is to start by producing substituted function types for accessors. Accessors are an important case because the coroutine continuation function is essentially an implicit component of the function type which the current substitution rules simply erase the intended abstraction of. They're also used in narrower ways that should exercise less of the optimizer.
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.
https://forums.swift.org/t/improving-the-representation-of-polymorphic-interfaces-in-sil-with-substituted-function-types/29711
This prepares SIL to be able to more accurately preserve the calling convention of
polymorphic generic interfaces by letting the type system represent "substituted function types".
We add a couple of fields to SILFunctionType to support this:
- A substitution map, accessed by `getSubstitutions()`, which maps the generic signature
of the function to its concrete implementation. This will allow, for instance, a protocol
witness for a requirement of type `<Self: P> (Self, ...) -> ...` for a concrete conforming
type `Foo` to express its type as `<Self: P> (Self, ...) -> ... for <Foo>`, preserving the relation
to the protocol interface without relying on the pile of hacks that is the `witness_method`
protocol.
- A bool for whether the generic signature of the function is "implied" by the substitutions.
If true, the generic signature isn't really part of the calling convention of the function.
This will allow closure types to distinguish a closure being passed to a generic function, like
`<T, U> in (*T, *U) -> T for <Int, String>`, from the concrete type `(*Int, *String) -> Int`,
which will make it easier for us to differentiate the representation of those as types, for
instance by giving them different pointer authentication discriminators to harden arm64e
code.
This patch is currently NFC, it just introduces the new APIs and takes a first pass at updating
code to use them. Much more work will need to be done once we start exercising these new
fields.
This does bifurcate some existing APIs:
- SILFunctionType now has two accessors to get its generic signature.
`getSubstGenericSignature` gets the generic signature that is used to apply its
substitution map, if any. `getInvocationGenericSignature` gets the generic signature
used to invoke the function at apply sites. These differ if the generic signature is
implied.
- SILParameterInfo and SILResultInfo values carry the unsubstituted types of the parameters
and results of the function. They now have two APIs to get that type. `getInterfaceType`
returns the unsubstituted type of the generic interface, and
`getArgumentType`/`getReturnValueType` produce the substituted type that is used at
apply sites.
With the advent of dynamic_function_ref the actual callee of such a ref
my vary. Optimizations should not assume to know the content of a
function referenced by dynamic_function_ref. Introduce
getReferencedFunctionOrNull which will return null for such function
refs. And getInitialReferencedFunction to return the referenced
function.
Use as appropriate.
rdar://50959798
