This change emits debug info for witness tables passed into generic
functions when a generic type is constrained to a protocol. This
information is required for LLDB's generic expression evaluator
to work in such functions.
rdar://104446865
Introduce a new runtime entry point, swift_getAssociatedConformanceWitness(),
which extracts an associated conformance witness from a witness table.
Teach IRGen to use this entry point rather than loading the witness
from the witness table and calling it directly.
There’s no advantage to doing this now, but it is staging for changing the
representation of associated conformances in witness tables.
When we’re creating an associated type witness metadata accessor for
resilience reasons, but the associated type witness doesn’t involve any
type parameters, directly form the type metadata reference (and don’t
cache it).
While here… update all of the IRGen/SILGen test cases perturbed by the
introduction of resilient associated type access patterns.
This includes global generic and non-generic global access
functions, protocol associated type access functions,
swift_getGenericMetadata, and generic type completion functions.
The main part of this change is that the functions now need to take
a MetadataRequest and return a MetadataResponse, which is capable
of expressing that the request can fail. The state of the returned
metadata is reported as an second, independent return value; this
allows the caller to easily check the possibility of failure without
having to mask it out from the returned metadata pointer, as well
as allowing it to be easily ignored.
Also, change metadata access functions to use swiftcc to ensure that
this return value is indeed returned in two separate registers.
Also, change protocol associated conformance access functions to use
swiftcc. This isn't really related, but for some reason it snuck in.
Since it's clearly the right thing to do, and since I really didn't
want to retroactively tease that back out from all the rest of the
test changes, I've left it in.
Also, change generic metadata access functions to either pass all
the generic arguments directly or pass them all indirectly. I don't
know how we ended up with the hybrid approach. I needed to change all
the code-generation and calls here anyway in order to pass the request
parameter, and I figured I might as well change the ABI to something
sensible.
Extend witness tables with a pointer to the protocol conformance
descriptor from which the witness table was generated. This will allow
us to determine (for example) whether two witness tables were
generated from the same (or equivalent) conformances in the future, as
well as discover more information about the witness table itself.
Fixes rdar://problem/36287959.
When forming a conformance access path, remove from consideration any
requirement sources that contain protocol requirements that aren't
found in the requirement signature. This ensure well-formedness of the
resulting conformance access path. Huge thanks to Slava for reducing
this one, and apologies to Arnold for having to track it down a second
time before I fixed it.
Fixes SR-6200 / rdar://problem/35113583.
