initialization in-place on demand. Initialize parent metadata
references correctly on struct and enum metadata.
Also includes several minor improvements related to relative
pointers that I was using before deciding to simply switch the
parent reference to an absolute reference to get better access
patterns.
Includes a fix since the earlier commit to make enum metadata
writable if they have an unfilled payload size. This didn't show
up on Darwin because "constant" is currently unenforced there in
global data containing relocations.
This patch requires an associated LLDB change which is being
submitted in parallel.
initialization in-place on demand. Initialize parent metadata
references correctly on struct and enum metadata.
Also includes several minor improvements related to relative
pointers that I was using before deciding to simply switch the
parent reference to an absolute reference to get better access
patterns.
"minimal" is defined as the set of requirements that would be
passed to a function with the type's generic signature that
takes the thick metadata of the parent type as its only argument.
Similarly to how we've always handled parameter types, we
now recursively expand tuples in result types and separately
determine a result convention for each result.
The most important code-generation change here is that
indirect results are now returned separately from each
other and from any direct results. It is generally far
better, when receiving an indirect result, to receive it
as an independent result; the caller is much more likely
to be able to directly receive the result in the address
they want to initialize, rather than having to receive it
in temporary memory and then copy parts of it into the
target.
The most important conceptual change here that clients and
producers of SIL must be aware of is the new distinction
between a SILFunctionType's *parameters* and its *argument
list*. The former is just the formal parameters, derived
purely from the parameter types of the original function;
indirect results are no longer in this list. The latter
includes the indirect result arguments; as always, all
the indirect results strictly precede the parameters.
Apply instructions and entry block arguments follow the
argument list, not the parameter list.
A relatively minor change is that there can now be multiple
direct results, each with its own result convention.
This is a minor change because I've chosen to leave
return instructions as taking a single operand and
apply instructions as producing a single result; when
the type describes multiple results, they are implicitly
bound up in a tuple. It might make sense to split these
up and allow e.g. return instructions to take a list
of operands; however, it's not clear what to do on the
caller side, and this would be a major change that can
be separated out from this already over-large patch.
Unsurprisingly, the most invasive changes here are in
SILGen; this requires substantial reworking of both call
emission and reabstraction. It also proved important
to switch several SILGen operations over to work with
RValue instead of ManagedValue, since otherwise they
would be forced to spuriously "implode" buffers.
- Implement emission of type references for nominal type field
reflection, using a small custom encoder resulting in packed
structs, not strings. This will let us embed 7-bit encoded
32-bit relative offsets directly in the structure (not yet
hooked in).
- Use the AST Mangler for encoding type references
Archetypes and internal references were complicating this before, so we
can take the opportunity to reuse this machinery and avoid unique code
and new ABI.
Next up: Tests for reading the reflection sections and converting the
demangle tree into a tree of type references.
Todo: For concrete types, serialize the types for associated types of
their conformances to bootstrap the typeref substitution process.
rdar://problem/15617914
This is a preliminary refactoring toward emitting generic metadata
instantiation accessors. This will let us stop exporting metadata
template symbols and reference accessors from conformance tables
instead. The latter is required to enable conformances where the
conforming type is resilient.
This was fixed by Luke Howard as part of some other changes in the
following patch:
<b5880f386b>
After rebasing my fix, I noticed most of it disappeared.
However, it's still worth checking in the tests.
Fixes <rdar://problem/24183374>.
of associated types in protocol witness tables.
We use the global access functions when the result isn't
dependent, and a simple accessor when the result can be cheaply
recovered from the conforming metadata. Otherwise, we add a
cache slot to a private section of the witness table, forcing
an instantiation per conformance. Like generic type metadata,
concrete instantiations of generic conformances are memoized.
There's a fair amount of code in this patch that can't be
dynamically tested at the moment because of the widespread
reliance on recursive expansion of archetypes / dependent
types. That's something we're now theoretically in a position
to change, and as we do so, we'll test more of this code.
This speculatively re-applies 7576a91009,
i.e. reverts commit 11ab3d537f.
We have not been able to duplicate the build failure in
independent testing; it might have been spurious or unrelated.
of associated types in protocol witness tables.
We use the global access functions when the result isn't
dependent, and a simple accessor when the result can be cheaply
recovered from the conforming metadata. Otherwise, we add a
cache slot to a private section of the witness table, forcing
an instantiation per conformance. Like generic type metadata,
concrete instantiations of generic conformances are memoized.
There's a fair amount of code in this patch that can't be
dynamically tested at the moment because of the widespread
reliance on recursive expansion of archetypes / dependent
types. That's something we're now theoretically in a position
to change, and as we do so, we'll test more of this code.
This reverts commit 6528ec2887, i.e.
it reapplies b1e3120a28, with a fix
to unbreak release builds.
This reverts commit b1e3120a28.
Reverting because this patch uses WitnessTableBuilder::PI in NDEBUG code.
That field only exists when NDEBUG is not defined, but now NextCacheIndex, a
field that exists regardless, is being updated based on information from PI.
This problem means that Release builds do not work.
ClassLayoutBuilder computes a bunch of stuff in addition to the
StructLayout, which is then stashed in ClassTypeInfo. Extract this
into a new ClassLayout type. It probably should not exist at all,
if we only generalized StructLayout a bit.
of associated types in protocol witness tables.
We use the global access functions when the result isn't
dependent, and a simple accessor when the result can be cheaply
recovered from the conforming metadata. Otherwise, we add a
cache slot to a private section of the witness table, forcing
an instantiation per conformance. Like generic type metadata,
concrete instantiations of generic conformances are memoized.
There's a fair amount of code in this patch that can't be
dynamically tested at the moment because of the widespread
reliance on recursive expansion of archetypes / dependent
types. That's something we're now theoretically in a position
to change, and as we do so, we'll test more of this code.
This is the first part of making class method dispatch resilient.
If we have the following class hierarchy:
// Module A
class Parent {
func foo() {}
}
class Child : Parent {}
// Module B
class Grandchild : Child {
override func foo() {
super.foo()
}
}
dispatch to `Parent.foo` will be static via a `function_ref`, so if
someone adds a `foo()` to `Child` later on, `Grandchild` won't know
about it without recompiling.
Stage in the IRGen portion of dynamic dispatch when calling methods on
`super`:
- Don't assert in IRGen if we see a native super_method instruction.
- Perform virtual lookup on superclass's metadata. If we see a
`super_method` instruction for a native class:
- Get the address of the superclass's metadata at offset 1
- Load the superclass's metadata
- Perform virtual lookup on this metadata instead
TODO: SILGen super_method instructions for native classes.
TODO: Devirtualize back down to static dispatch with a reslience lookup
mechanism.
rdar://problem/22749732
If a struct has fixed layout but contains fields which are opaque,
or if the struct itself is opaque, use a metadata accessor function
instead of loading the metadata directly.
Let's say that A and B are two structs defined in the same module,
and B has a fixed size. This patch adds support for these two cases:
1) Fixed-layout struct A contains resilient struct B
2) Resilient struct A contains resilient struct B
In case 1),
a) Inside X: A is fixed-size and has constant metadata
i) Direct metadata access can be performed on A and B
ii) Direct field access can be performed on A and B
d) Outside X: B has an opaque layout
i) Metadata accessor must be called for A and B
ii) Fields of A do not have constant offsets, instead the offsets
must be loaded from type metadata
Case 2) is the same as above except ii) does not apply, since fields
of resilient structs are manipulated via accessors.
Eventually, we will use metadata accessor functions for all public
struct and enum types.
NFC, but this set of access modes applies more generally to other kinds of metadata that may need to be guarded by accessors, such as witness tables.
Swift SVN r31838
Full type metadata isn't necessary to calculate the runtime layout of a dependent struct or enum; we only need the non-function data from the value witness table (size, alignment, extra inhabitant count, and POD/BT/etc. flags). This can be generated more efficiently than the type metadata for many types--if we know a specific instantiation is fixed-layout, we can regenerate the layout information, or if we know the type has the same layout as another well-known type, we can get the layout from a common value witness table. This breaks a deadlock in most (but not all) cases where a value type is recursive using classes or fixed-layout indirected structs like UnsafePointer. rdar://problem/19898165
This time, factor out the ObjC-dependent parts of the tests so they only run with ObjC interop.
Swift SVN r30266
Full type metadata isn't necessary to calculate the runtime layout of a dependent struct or enum; we only need the non-function data from the value witness table (size, alignment, extra inhabitant count, and POD/BT/etc. flags). This can be generated more efficiently than the type metadata for many types--if we know a specific instantiation is fixed-layout, we can regenerate the layout information, or if we know the type has the same layout as another well-known type, we can get the layout from a common value witness table. This breaks a deadlock in most (but not all) cases where a value type is recursive using classes or fixed-layout indirected structs like UnsafePointer. rdar://problem/19898165
Swift SVN r30243
It looks like John and Joe already did a good part of this. The previous
patch to enable polymorphic @objc_method signatures takes us further, and
I think this patch fills in the rest.
Fixes <rdar://problem/18505295>, <rdar://problem/20700287>.
Swift SVN r29259
It looks like John and Joe already did a good part of this. The previous
patch to enable polymorphic @objc_method signatures takes us further, and
I think this patch fills in the rest.
Fixes <rdar://problem/18505295>, <rdar://problem/20700287>.
Swift SVN r29137
Store the number of payload and no-payload cases, the case names, and a lazy case type accessor function for enums, like we do for stored properties of structs and classes. This will be useful for multi-payload runtime support, and should also be enough info to hack together a reflection implementation for enums.
For dynamic multi-payload enums to not be ridiculously inefficient, we'll need to track the size of the payload area in the enum, like we do the field offsets of generic structs and classes, so hack off a byte in the payload case count to track the offset of that field in metadata records. 16 million payloads ought to be enough for anyone, right? (and 256 words between the enum metadata's address point and the payload size offset)
Swift SVN r27789
The field type generator may end up producing recursive static references to metadata while we're generating metadata. Fixes rdar://problem/19838839.
Swift SVN r25534
Previously, we were not respecting the representation of the existential
metatype and were treating all existential metatypes as if the metatype
was a thick metatype. Instead now we properly grab the instance of the
class from the existential and then query the runtime for the
objc_class. This is done via the new entrypoint
emitHeapMetadataRefForUnknownHeapObject.
I also modified emitHeapMetadataRefForHeapObject to use
emitHeapMetadataRefForUnknownHeapObject instead of
emitLoadOfObjCHeapMetadataRef since the latter does not properly handle
tagged pointers. This bug was found on inspection when Joe and I were
talking about this change.
rdar://18841292
Swift SVN r23308
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
If a type has to be passed or returned resiliently, it
will necessarily be passed indirectly, which is already
represented in SILFunctionType. There is no need to
represent this as a separate channel of information.
NFC. Also fixes a problem where the signature cache
for ExtraData::Block was writing past the end of an
array (but into the storage for an adjacent array
which was fortunately never used).
ExtraData should also disappear as a concept, but we're
still relying on that for existential protocol witnesses.
Swift SVN r21548
unexpected forematter from the superclass.
This requires a pretty substantial shift in the
generic-metadata allocation/initialization dance
because (1) we can't allocate class metadata without
knowing what the superclass is and (2) the offset
from the metadata cache entry to the address point is
no longer determined solely by the metadata pattern.
While I'm making invasive changes to metadata, fix
two race conditions in metadata creation. The first
is that we need to ensure that only one thread succeeds
at lazily creating a generic-metadata cache. The second
is that we need to ensure that only one thread actually
attempts to create a particular metadata; any others
should block until the metadata is successfully built.
This commit finishes rdar://17776354. LLDB will
need to adjust to the runtime-private metadata layout
changes.
Swift SVN r20537
functions, and make those functions memoize the result.
This memoization can be both threadsafe and extremely
fast because of the memory ordering rules of the platforms
we're targeting: x86 is very permissive, and ARM has a
very convenient address-dependence rule which happens to
exactly match the semantics we need.
Swift SVN r20381
Create a global alias into the metadata of @objc-visible classes at their address point, which should make these classes visible for linking from ObjC, fixing <rdar://problem/14449644>.
Swift SVN r15921
LLVM doesn't have interior symbols as a first-class concept, so generate module inline asm that defines the OBJC_CLASS symbol relative to the Swift metadata symbol. To prevent our system linkers from considering this symbol as the start of a new object and breaking apart class metadata objects, put the class metadata object into a no_dead_strip section.
This isn't quite enough to get the OBJC_CLASS symbol to be available--the symbol appears to show up in the .o as an undefined symbol and stripped out of the .dylib. John is investigating with the backend and linker teams as to why this is the case.
Swift SVN r14927
Emit vtable entries for abstract initializers. When we're constructing
an object using an abstract initializer based on a metatype value that
is not statically derivable, use the vtable entry to call the
subclass's allocating constructor.
Most of the IRGen work here is hacking around the lossy SILDeclRef ->
(Code|Function)Ref -> SILDeclRef conversion. I'd feel bad about this
if John hadn't already agreed to clean this up at some point.
Swift SVN r14238
