Emit a 16-bit constant that tracks the version of the reflection
metadata emitted into binaries. This can be used to cross-check
what is supported by the SwiftRemoteMirror library with the new
version API.
rdar://problem/27251582
The approach here is to split this into two cases:
- If all case payloads have a fixed size, spare bits may be
potentially used to differentiate between cases, and the
remote reflection library does not have enough information to
compute the layout itself.
However, the total size must be fixed, so IRGen just emits a
builtin type descriptor (which I need to rename to 'fixed type
descriptor' since these are also used for imported value types,
and now, certain enums).
- If at least one case has a size that depends on a generic
parameter or is a resilient type, IRGen does not know the size,
but this means fancy tricks with spare bits cannot be used either.
The remote reflection library uses the same approach as the
runtime, basically taking the maximum of the payload size and
alignment, and adding a tag byte.
As with single-payload enums, we produce a new kind of
RecordTypeInfo, this time with a field for every enum case.
All cases start at offset zero (but of course this might change,
if for example we put the enum tag before the address point).
Also, just as with single-payload enums, there is no remote
'project case index' operation on ReflectionContext yet.
So the the main benefit from this change is that we don't entirely
give up when doing layout of class instances containing enums;
however, tools still cannot look inside the enum values themselves,
except in the simplest cases involving optionals.
Notably, the remote reflection library finally understands all
of the standard library's collection types -- Array, Character,
Dictionary, Set, and String.
Attempt to lay out single-payload enums, using knowledge of extra
inhabitants where possible.
- The extra inhabitants of an aggregate are the extra inhabitants of
the first field. If the first field is empty, there are no extra
inhabitants, and subsequent fields do not affect anything.
- Function pointers and metatypes have different extra inhabitants
than Builtin.RawPointer, so have IRGen emit distinct builtin type
descriptors for those.
- Opaque existentials do not have extra inhabitants.
- Weak references do not have extra inhabitants.
Also, fix IRGen to emit more accurate enum reflection metadata in
these two cases:
- We now record whether enum cases are indirect or not. An indirect
case is the same as a payload case with Builtin.NativeObject.
- We now record whether a case is empty or not using the same logic
as the rest of IRGen. Previously, we would incorrectly emit a
payload type for a case with a payload that is an empty struct,
for example.
At this point we don't have a way to get the currently inhabited
enum case from a value. However, this is still an improvement because
we can still reflect other fields of aggregates containing enums,
instead of just giving up.
Finally make some methods on TypeCoverter private, and use 'friend'
to allow them to be accessed from other internal classes, making the
public API simpler.
COFF has restrictions on portable section length (8 characters). Use a FourCC
identifier for the section on COFF. Take the opportunity to replace a
std::string parameter with a StringRef.
Instead of hooking into nominal type and extension emission
and walking all conformances of those declarations, let's
just directly hook into the logic for emitting conformances.
This fixes an issue where we would apparently emit duplicate
conformances, as well as unnecessary conformances that are
defined elsewhere.
When we encounter a protocol typeref, we have to know if its @objc,
class-bound, or opaque, so make sure we provide the necessary
information when imported protocols are referenced.
While we can skip emitting metadata for imported classes (clients
should ask the Objective-C runtime instead) it was not correct to
do so for Swift-defined classes that used Objective-C reference
counting.
Previously we would emit both a builtin descriptor and field
descriptor for imported classes, but we only need the latter.
Untangle some code and fix a crash with imported Objective-C
generics in the process.
Fixes <rdar://problem/26498484>.
We were recovering metadata from generic boxes by reading
the instantiated payload metadata from the box's metadata,
but this approach doesn't work for fixed-size boxes, whose
metadata does not store the payload metadata at all.
Instead, emit a capture descriptor with no metadata sources
and a single capture, using the lowered AST type appearing
in the alloc_box instruction that emitted the box.
Since box metadata is shared by all POD types of the same
size, and all single-retainable pointer payloads, the
AST type might not accurately reflect what is actually in
the box.
However, this type is *layout compatible* with the box
payload, at least enough to know where the retainable
pointers are, because after all IRGen uses this type to
synthesize the destructor.
Fixes <rdar://problem/26314060>.
When emitting capture descriptors for functions with a smaller number of parameters
than SIL parameters, the compiler can crash indexing into the heap layout's element
types, because the capture index underflows to UINT_MAX.
rdar://problem/26404583
- Lower Objective-C class typerefs as strong references with unknown
reference counting.
- Lower other imported C types as builtin blobs of their known
size, alignment, etc.
In the future, it might be beneficial to track which stored properties
of imported types are pointers, for better conservative scanning of
outgoing pointers to the heap.
rdar://problem/26240258
rdar://problem/26240394
Getting metadata from a metatype source just means loading from an offset;
with a reference source we have to dereference the isa pointer first.
Thanks to @bitjammer for pointing out this was broken.
- Fix caller/callee confusion, and use the right SIL function type
for obtaining the generic signature.
- Correctly interpret the NecessaryBindings structure and the
substitutions therein.
- Fix alignment for capture and builtin type descriptors
- Put capture descriptor typerefs in the correct section
Add new SIL-level tests to precisely trigger various scenarios.
Rather than collection nominal type and extension decls and emit
reflection metadata records in one go, we can emit them as they
are encountered and instead collection builtin types referenced
by those at the end.
If there are any builtin types referenced by closure captures
[in the standard library], make sure to collect them so we emit
reflection metadata for them in the builtin section.
For now, just enough for lowering.
Perhaps we should have a way to always just get this information
from metadata instead, since protocol metadata is always static
and not instantiated.
This would require the static "object file" interface used by
swift-reflection-dump to take a callback for symbol lookup.
These types are not directly referenced as fields of aggregate types,
but are needed for reflection type lowering.
Also, use a SetVector to collect referenced builtin types, instead of
a SmallPtrSet, to ensure compiler output is deterministic.
MCJIT doesn't like offset relocations into the data sections, so the
capture descriptors and their typerefs/metadata source encoded strings
will need to be emitted as globals and not go into the reflection data
sections.
For convenience when reading looking at heap closure metadata.
Also move the capture typerefs above the metadata sources, since
they're more likely to be accessed than generic metadata sources.
Now we can discern the types of values in heap boxes at runtime!
Closure reference captures are a common way of creating reference
cycles, so this provides some basic infrastructure for detecting those
someday.
A closure capture descriptor has the following:
- The number of captures.
- The number of sources of metadata reachable from the closure.
This is important for substituting generics at runtime since we
can't know precisely what will get captured until we observe a
closure.
- The number of types in the NecessaryBindings structure.
This is a holding tank in a closure for sources of metadata that
can't be gotten from the captured values themselves.
- The metadata source map, a list of pairs, for each
source of metadata for every generic argument needed to perform
substitution at runtime.
Key: The typeref for the generic parameter visible from the closure
in the Swift source.
Value: The metadata source, which describes how to crawl the heap from
the closure to get to the metadata for that generic argument.
- A list of typerefs for the captured values themselves.
Follow-up: IRGen tests for various capture scenarios, which will include
MetadataSource encoding tests.
rdar://problem/24989531
In order to perform layout, the remote mirrors library needs to know
about the size, alignment and extra inhabitants of builtin types.
Ideally we would emit a reflection info section in libswiftRuntime.o,
but in the meantime just duplicate builtin type metadata for all
builtin types referenced from the current module instead.
In practice only the stdlib and a handful of overlays like the SIMD
overlay use builtin types, and only a few at a time.
Tested manually by running swift-reflection-tool on the standard
library -- I'll add automated tests by using -parse-stdlib to
reference Builtin types in a subsequent patch that adds more layout
logic.
NFC if -enable-reflection-metadata is off.
Otherwise, we will insert padding if the field metadata section size
is not a multiple of the word size, which will cause a crash when
we later try to read it.
This turns on the remote reflection metadata by default for swift
invocations and the standard library. The size delta for all of the
sections is:
Section __swift3_typeref: 20176
Section __swift3_reflstr: 2556
Section __swift3_fieldmd: 8172
Section __swift3_assocty: 18112
Recognizing that this is a nontrivial increase in binary size, we can
reduce this with a few methods:
- Trie for strings (typerefs and field names are both strings) but would
need an implementation
- Compress the entire sections: this would need an implementation
available on all platforms where we support the functionality.
- Don't use the AST mangler but a custom mangling, which may be slightly
more compact because it can specialize by need and maybe not include
some mangle nodes that typerefs don't need.
Similiar to the change to field reflection metadata, don't use the
interface for the key of associated type lookup, because the nominal
type descriptors don't include generics in their mangled name strings.
Nominal type descriptors use declared types for their mangled names,
so we need to use them when scanning the fieldmd section for a
matching record. This is fine because the descriptor can tell us
about the type's generics. Individual field records continue to use
the interface type.
These likely don't have Swift type metadata but might be useful to
record or instantiate based on what kind of metadata is encountered for
the sake of memory tools.
