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.
Prevent the optimizer from eliminating alloc_box instructions
in box_descriptors.sil by returning the boxes, and inhibit
literal capture propagation in functions.swift.
Fixes <rdar://problem/26561954>.
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>.
Child processes were exiting too early before the parent has a chance
to read a null pointer from the child, indicating that there are no
more instances to reflect. This wasn't a problem on OS X because the
I/O latency is so small compared to the iOS simulator, where the
problem would come up under heavy load. This makes the end-to-end
remote mirror tests deterministic again.
rdar://problem/26230879
There is an issue with writing to pipes under heavy load in the iOS
simulator but is intermittent. Disabling the tests there while I
investigate.
rdar://problem/26230879
Without this, offsets of captures in closure contexts may be
incorrect if there is a non-empty necessary bindings structure
at the front.
rdar://problem/26312900
Also add end-to-end tests for this finally, and fix a bug in
the SwiftReflectionTest library where we would give up on an
module completely if it did not have a field metadata section.
This is of course wrong if the module defines closures but
not nominal types.
