Implement SIL generation for "async let" constructs, which involves:
1. Creating a child task future at the point of declaration of the "async let",
which runs the initializer in an async closure.
2. Entering a cleanup to destroy the child task.
3. Entering a cleanup to cancel the child task.
4. Waiting for the child task when any of the variables is reference.
5. Decomposing the result of the child task to write the results into the
appropriate variables.
Implements rdar://71123479.
Rather than produce an "unowned" result from `getCurrentAsyncTask()`,
take advantage of the fact that the task is effectively guaranteed in
the scope. Do so be returning it as "unowned", and push an
end_lifetime cleanup to end the lifetime. This eliminates unnecessary
ref-count traffic as well as introducing another use of unowned.
Approach is thanks to Michael Gottesman, bugs are mine.
This has been a long standing issue that we have been hacking around in various
points in SILGen. Now CleanupCloner just does the right thing.
I was unable to cause any issues to pop up in tree (since I believe we hacked
around this and converged on correctness). But it does come up in combination
with new code in https://github.com/apple/swift/pull/31779.
rdar://63514765
VarPattern is today used to implement both 'let' and 'var' pattern bindings, so
today is already misleading. The reason why the name Var was chosen was done b/c
it is meant to represent a pattern that performs 'variable binding'. Given that
I am going to add a new 'inout' pattern binding to this, it makes sense to
give it now a better fitting name before I make things more confusing.
* [SILGenFunction] Don't create redundant nested debug scopes
Instead of emitting:
```
sil_scope 4 { loc "main.swift":6:19 parent 3 }
sil_scope 5 { loc "main.swift":7:3 parent 4 }
sil_scope 6 { loc "main.swift":7:3 parent 5 }
sil_scope 7 { loc "main.swift":7:3 parent 5 }
sil_scope 8 { loc "main.swift":9:5 parent 4 }
```
Emit:
```
sil_scope 4 { loc "main.swift":6:19 parent 3 }
sil_scope 5 { loc "main.swift":7:3 parent 4 }
sil_scope 6 { loc "main.swift":9:5 parent 5 }
```
* [IRGenSIL] Diagnose conflicting shadow copies
If we attempt to store a value with the wrong type into a slot reserved
for a shadow copy, diagnose what went wrong.
* [SILGenPattern] Defer debug description of case variables
Create unique nested debug scopes for a switch, each of its case labels,
and each of its case bodies. This looks like:
```
switch ... { // Enter scope 1.
case ... : // Enter scope 2, nested within scope 1.
<body-1> // Enter scope 3, nested within scope 2.
case ... : // Enter scope 4, nested within scope 1.
<body-2> // Enter scope 5, nested within scope 4.
}
```
Use the new scope structure to defer emitting debug descriptions of case
bindings. Specifically, defer the work until we can nest the scope for a
case body under the scope for a pattern match.
This fixes SR-7973, a problem where it was impossible to inspect a case
binding in lldb when stopped at a case with multiple items.
Previously, we would emit the debug descriptions too early (in the
pattern match), leading to duplicate/conflicting descriptions. The only
reason that the ambiguous description was allowed to compile was because
the debug scopes were nested incorrectly.
rdar://41048339
* Update tests
Switch most callers to explicit indices. The exceptions lie in things that needs to manipulate the parsed output directly including the Parser and components of the ASTScope. These are included as friend class exceptions.
This removes an intricate set of invariants that must be kept consistent
between Parse and SILGen. It will also make it easier to implement local
variables with 'lazy' and property wrappers in the future.
Just as with conformances, we can detect that a delayed function
needs to be added to the queue from 'first principles' rather than
walking the ExternalDefinitions list.
This completely eliminates the ExternalDefinitions walk from SILGen,
which has several advantages:
- It fixes a source of quadratic behavior. In batch mode, type checking
produces a list of external definitions shared across all primary
files. Then, SILGen runs once per primary file, building a delayed
emission map every time.
- It allows SILGen to emit external definitions which only come into
existence as a result of lazy conformance checking. Previously,
anything that was added after SILGen performed its walk over the
external definitions list would not be emitted.
Instead of visiting all types in the ExternalDefinitions list and
queuing up their conformances, just emit conformances as needed
when they are first referenced.
ManagedValue::{forward,assign}Into both have the signature SILGenFunction &,
SILLocation, SILValue. For some reason copyInto has SILLocation and SILValue
swapped. This commit standardizes copyInto to match the others.
These can be recreated if needed in a client library. To do this, I've
added a new ConformanceLookupKind::NonInherited, which can also be
used elsewhere in the project where we're already filtering out
inherited conformances some other way.
Note that this doesn't drop inherited conformances from the entire
serialized interface, just from the list that a class explicitly
declares. They still get referenced sometimes.
rdar://problem/50541451 and possibly others
This is a large patch; I couldn't split it up further while still
keeping things working. There are four things being changed at
once here:
- Places that call SILType::isAddressOnly()/isLoadable() now call
the SILFunction overload and not the SILModule one.
- SILFunction's overloads of getTypeLowering() and getLoweredType()
now pass the function's resilience expansion down, instead of
hardcoding ResilienceExpansion::Minimal.
- Various other places with '// FIXME: Expansion' now use a better
resilience expansion.
- A few tests were updated to reflect SILGen's improved code
generation, and some new tests are added to cover more code paths
that previously were uncovered and only manifested themselves as
standard library build failures while I was working on this change.
Currently Sema completes all _ObjectiveCBridgeable conformances it thinks
are needed in SILGen and runtime dynamic casts, but that's about to change.
When emitting conformances for an imported type we would skip incomplete
conformances. Now that we have a long-lived type checker instance, there
is no longer any reason to do that. Looking up witnesses from an
incomplete conformance will trigger conformance checking as needed.
Furthermore, conformances emitted in this path are emitted lazily, so if
a conformance is not used, no conformance checking will take place.
A change in behavior only occurs after subsequent changes to remove Sema's
eager checking of ClangImporter-synthesized _ObjectiveCBridgeable
conformances; at that point, we must be prepared to lazily emit these
incomplete conformances.
The initializer associated with a lazy property should not be executed
directly, because it is subsumed by code synthesized into the
getter. Generalize the terminology here so we can re-use this path for
property delegate initialization.
To represent the abstracted interface of an opaque type, we need a generic signature that refines
the outer context generic signature with an additional generic parameter representing the underlying
type and its exposed constraints. Opaque types also need to be keyed by their originating decl, so
that we can treat values of the same opaque type as the same. When we check a FuncDecl with an
opaque type specified as its return type, create an OpaqueTypeDecl and associate it with the
originating decl. (A representation for *types* derived from the opaque decl will come next.)
Sorting of DeclContext-local protocols and conformances shouldn't ever
be necessary, because the underlying data structures that produce
these lists should be deterministic. Sorting can hide any
non-determinism, so stop doing it and we can address the underlying
nondeterminism.
Removes the _getBuiltinLogicValue intrinsic in favor of an open-coded
struct_extract in SIL. This removes Sema's last non-literal use of builtin
integer types and unblocks a bunch of cleanup.
This patch would be NFC, but it improves line information for conditional expression codegen.
When an on-demand accessor is synthesized while checking a conformance,
make sure it ends up in the 'external declarations' list so that SILGen
can emit it.
Fixes <rdar://problem/46503121>, and part of <rdar://problem/46186045>.
The problem here is that we were taking advantage of swift not-trashing the
original memory location after performing a load [take] to use load [take] as a
+0 load. This breaks the ownership verifier since the load [take] is never
actually destroyed. Instead this commit changes this code to use a load_borrow.
I found this when trying to enable ownership verification on
test/SILGen/indirect_enum.swift using some out of tree work that should have
fixed all of the ownership issues with SILGenPattern. Turns out I can just
enable ownership verification with just this change... so I did that as well in
this PR.
rdar://29791263
Delay allocating the result buffer for an opened Self return until right before it's needed. When a mutating method is invoked on an existential, the Self type won't be opened until late, when the formal access to the mutable value begins. Fixes rdar://problem/43507711.
