The majority of support comes in the form of emitting partial
application forwarders for partial applications of async functions.
Such a partial application forwarder must take an async context which
has been partially populated at the apply site. It is responsible for
populating it "the rest of the way". To do so, like sync partial
application forwarders, it takes a second argument, its context, from
which it pulls the additional arguments which were capture at
partial_apply time.
The size of the async context that is passed to the forwarder, however,
can't be known at the apply site by simply looking at the signature of
the function to be applied (not even by looking at the size associated
with the function in the special async function pointer constant which
will soon be emitted). The reason is that there are an unknown (at the
apply site) number of additional arguments which will be filled by the
partial apply forwarder (and in the case of repeated partial
applications, further filled in incrementally at each level). To enable
this, there will always be a heap object for thick async functions.
These heap objects will always store the size of the async context to be
allocated as their first element. (Note that it may be possible to
apply the same optimization that was applied for thick sync functions
where a single refcounted object could be used as the context; doing so,
however, must be made to interact properly with the async context size
stored in the heap object.)
To continue to allow promoting thin async functions to thick async
functions without incurring a thunk, at the apply site, a null-check
will be performed on the context pointer. If it is null, then the async
context size will be determined based on the signature. (When async
function pointers become pointers to a constant with a size i32 and a
relative address to the underlying function, the size will be read from
that constant.) When it is not-null, the size will be pulled from the
first field of the context (which will in that case be cast to
<{%swift.refcounted, i32}>).
To facilitate sharing code and preserving the original structure of
emitPartialApplicationForwarder (which weighed in at roughly 700 lines
prior to this change), a new small class hierarchy, descending from
PartialApplicationForwarderEmission has been added, with subclasses for
the sync and async case. The shuffling of arguments into and out of the
final explosion that was being performed in the synchronous case has
been preserved there, though the arguments are added and removed through
a number of methods on the superclass with more descriptive names. That
was necessary to enable the async class to handle these different
flavors of parameters correctly.
To get some initial test coverage, the preexisting
IRGen/partial_apply.sil and IRGen/partial_apply_forwarder.sil tests have
been duplicated into the async folder. Those tests cases within these
files which happened to have been crashing have each been extracted into
its own runnable test that both verifies that the compiler does not
crash and also that the partial application forwarder behaves correctly.
The FileChecks in these tests are extremely minimal, providing only
enough information to be sure that arguments are in fact squeezed into
an async context.
When the first element in the heap layout was non fixed we would use the
mininum size of the total heap layout for the initial offset. This would
create unneccessary large heap layouts.
rdar://61716736
Motivation: `GenericSignatureImpl::getCanonicalSignature` crashes for
`GenericSignature` with underlying `nullptr`. This led to verbose workarounds
when computing `CanGenericSignature` from `GenericSignature`.
Solution: `GenericSignature::getCanonicalSignature` is a wrapper around
`GenericSignatureImpl::getCanonicalSignature` that returns the canonical
signature, or `nullptr` if the underlying pointer is `nullptr`.
Rewrite all verbose workarounds using `GenericSignature::getCanonicalSignature`.
This mostly requires changing various entry points to pass around a
TypeConverter instead of a SILModule. I've left behind entry points
that take a SILModule for a few methods like SILType::subst() to
avoid creating even more churn.
box descriptors
We want to substitute opaque result types in addTypeRef but when we pass
SILFunctionTypes this would fail because AST type substitution does not
support lowered SIL types.
Instead add addLoweredTypeRef which substitutes based on SILTypes.
rdar://54529445
In too many places, we were calling into `emitDynamicTypeOfOpaqueHeapObject` even when we had
more specific type information about the heap object we were querying. Replace all calls with
`emitDynamicTypeOfHeapObject`, which uses the best available access path and completely avoids
runtime calls for pure Swift classes and heap objects. When targeting non-ObjC-interop platforms,
we also know we never need to call `swift_getObjectType`, so avoid doing so altogether.
This indicates that the "self" argument to the current function is always dynamically of the exact
static base class type, allowing metadata accesses in IRGen to use the local self metadata to answer
metadata requests for the class type. Set this attribute on allocating entry points of designated
inits, which is one of the most common places where we emit redundant metadata accesses.
Don't use the beginning of the basic block as insertion point if 'local
self' is an llvm::Instruction (i.e a cast from the argument llvm::Value
has been insterted) rather use the 'local self' value as insertion point.
Fixes a dominance issue because we inserted at the beginning of the
basic block.
rdar://51186963
An @objc convenience initializer can replace 'self'. Since IRGen
has no way to tell what the new 'self' value is from looking at
SIL, it always refers back to the original 'self' argument when
recovering DynamicSelfType metadata. This could cause a crash
if the metadata was used after the 'self' value had been
replaced.
To fix the crash, always insert the metadata recovery into the
entry block, where the 'self' value should be valid (even if
uninitialized, the 'isa' pointer should be correct).
Fixes <rdar://problem/50594689>.
This simplifies some boilerplate, and in particular, some SIL verifier
logic; and fixes a couple bugs related to always loadable reference
storage types.
At Odebug we print the full path to the file and in optimized mode no
file name will be included.
This mirrors what we do in Swift's asserts.
rdar://47880964
This silences the instances of the warning from Visual Studio about not all
codepaths returning a value. This makes the output more readable and less
likely to lose useful warnings. NFC.
This does the same thing as taking the AST type and running it through mapTypeOutOfContext, but
saves call sites from having to do the unwrap-rewrap dance.
These functions don't accept local variable heap memory, although the names make it sound like they work on anything. When you try, they mistakenly identify such things as ObjC objects, call through to the equivalent objc_* function, and crash confusingly. This adds Object to the name of each one to make it more clear what they accept.
rdar://problem/37285743
This allows us to layout-optimize Optional<T> when T is a struct with an
extra-inhabitant-bearing field anywhere in its definition, not only at
the beginning. rdar://problem/43019427
ClassDecl::getSuperclass() produces a complete interface type describing the
superclass of a class, including any generic arguments (for a generic type).
Most callers only need the referenced ClassDecl, which is (now) cheaper
to compute: switch those callers over to ClassDecl::getSuperclassDecl().
Fixes an existing test for SR-5993.
A Swift subclass of an ObjC class can be dynamically subclassed, but `type(of:)` shouldn't return the artificial subclass, since that's not what -class does for ObjC classes, and people expect `Bundle(for: type(of: c))` to work like `[NSBundle bundleForClass: [c class]]` would in ObjC. Fixes rdar://problem/37319860.
When we use type(of: x) on a class in an ObjC bridged context, the optimizer turns this into a SIL `value_metatype @objc` operation, which is supposed to get the dynamic type of the object as an ObjC class. This was previously lowered by IRGen into a `object_getClass` call, which extracts the isa pointer from the object, but is inconsistent with the `-class` method in ObjC or with the Swift-native behavior, which both look through artificial subclasses, proxies, and so on. This inconsistency led to observably different behavior between debug and release builds and between ObjC-bridged and native entry points, so provide an alternative runtime entry point that replicates the behavior of getting a native Swift class. Fixes SR-7258.
Most of the work of this patch is just propagating metadata states
throughout the system, especially local-type-data caching and
metadata-path resolution. It took a few design revisions to get both
DynamicMetadataRequest and MetadataResponse to a shape that felt
right and seemed to make everything easier.
The design is laid out pretty clearly (I hope) in the comments on
DynamicMetadataRequest and MetadataResponse, so I'm not going to
belabor it again here. Instead, I'll list out the work that's still
outstanding:
- I'm sure there are places we're asking for complete metadata where
we could be asking for something weaker.
- I need to actually test the runtime behavior to verify that it's
breaking the cycles it's supposed to, instead of just not regressing
anything else.
- I need to add something to the runtime to actually force all the
generic arguments of a generic type to be complete before reporting
completion. I think we can get away with this for now because all
existing types construct themselves completely on the first request,
but there might be a race condition there if another asks for the
type argument, gets an abstract metadata, and constructs a type with
it without ever needing it to be completed.
- Non-generic resilient types need to be switched over to an IRGen
pattern that supports initialization suspension.
- We should probably space out the MetadataStates so that there's some
space between Abstract and Complete.
- The runtime just calmly sits there, never making progress and
permanently blocking any waiting threads, if you actually form an
unresolvable metadata dependency cycle. It is possible to set up such
a thing in a way that Sema can't diagnose, and we should detect it at
runtime. I've set up some infrastructure so that it should be
straightforward to diagnose this, but I haven't actually implemented
the diagnostic yet.
- It's not clear to me that swift_checkMetadataState is really cheap
enough that it doesn't make sense to use a cache for type-fulfilled
metadata in associated type access functions. Fortunately this is not
ABI-affecting, so we can evaluate it anytime.
- Type layout really seems like a lot of code now that we sometimes
need to call swift_checkMetadataState for generic arguments. Maybe
we can have the runtime do this by marking low bits or something, so
that a TypeLayoutRef is actually either (1) a TypeLayout, (2) a known
layout-complete metadata, or (3) a metadata of unknown state. We could
do that later with a flag, but we'll need to at least future-proof by
allowing the runtime functions to return a MetadataDependency.
Abstract type/heap metadata access goes into MetadataRequest.
Metadata access starting from a heap object goes into GenHeap.
Accessing various components of class metadata goes into GenClass
or MetadataLayout.
Will be used to verify that withoutActuallyEscaping's block does not
escape the closure.
``%escaping = is_escaping_closure %closure`` tests the reference count. If the
closure is not uniquely referenced it prints out and error message and
returns true. Otherwise, it returns false. The returned result can be
used with a ``cond_fail %escaping`` instruction to abort the program.
rdar://35525730
