Create a version of the metadata specialization code which is abstracted so that it can work in different contexts, such as building specialized metadata from dylibs on disk rather than from inside a running process.
The GenericMetadataBuilder class is templatized on a ReaderWriter. The ReaderWriter abstracts out everything that's different between in-process and external construction of this data. Instead of reading and writing pointers directly, the builder calls the ReaderWriter to resolve and write pointers. The ReaderWriter also handles symbol lookups and looking up other Swift types by name.
This is accompanied by a simple implementation of the ReaderWriter which works in-process. The abstracted calls to resolve and write pointers are implemented using standard pointer dereferencing.
A new SWIFT_DEBUG_VALIDATE_EXTERNAL_GENERIC_METADATA_BUILDER environment variable uses the in-process ReaderWriter to validate the builder by running it in parallel with the existing metadata builder code in the runtime. When enabled, the GenericMetadataBuilder is used to build a second copy of metadata built by the runtime, and the two are compared to ensure that they match. When this environment variable is not set, the new builder code is inactive.
The builder is incomplete, and this initial version only works on structs. Any unsupported type produces an error, and skips the validation.
rdar://116592420
For calloc, the variable denoting the of elements comes first,
then the variable denoting the size of each element. However, both
arguments are swapped when calling this function in many places in this codebase.
We can't use `malloc_type_aligned_alloc()` because `aligned_alloc()` requires
that `size` be a multiple of `alignment`, which isn't something we expect here.
rdar://119137861
In the event that the backtracer fails to suspend a thread, it emits a
warning message. Unfortunately the exact meaning of this message isn't
obvious and it doesn't make clear that it's a secondary problem (that is,
you've already crashed at this point).
Update the message to make things clearer.
rdar://116593541
The static bridgeableProtocol inherits the ptrauth_struct attribute which uses the B key, and that's not allowed on global data in the shared cache. Pass the value directly as a parameter instead.
rdar://118606044
The initWithTakeTable accidentally referenced bridgeRetain instead of copyingInitWithTake, which caused a leak when an object containing a bridge reference was also not bitwise takable.
Accessing the thread context structures is complicated because their
member variables change name depending on various macros. This caused
a build failure for ARM64e.
rdar://118402226
* [Runtime] Use threaded code in compact value witness runtime
These changed reduce branching and yield performance improvements of up to 10% for some cases.
* Fix offset in handleRefCountsInitWithTake
We shouldn't try to erase the message when in non-color mode; mostly
that's intended for redirected output scenarios anyway, and in that case
we don't really want garbage in the output.
Also, improve the failure messages when the backtracer itself goes
wrong or can't be executed.
Finally, change the behaviour slightly so that *if* we're explicitly
enabled, *and* the backtracer path wasn't explicitly specified, *and*
we can't find the backtracer, we print a warning on start-up. We
don't do that in any other case because we don't want spurious warnings
everywhere.
rdar://118055527
When we crash, emit a message straight away that says we're working
on a backtrace. If starting the backtracer fails, report that also.
Finally, add a duration to the messages output by the backtracer, so
that we can see how long it took.
rdar://118055527
Make SwiftValue hash/equality work the same as SwiftObject
For Equatable types that are not Hashable, this proxies ObjC `-isEqual:` to Swift `Equatable` and returns a constant for ObjC `-hash`
Thanks to a missing `-` sign, we were returning garbage rather than
indicating that the memory region in question was inaccessible. This
mainly affects register dumps (since that's the time we expect to have
to cope with out-of-bounds reads).
rdar://117900760
Update PR #68720 with lessons learned in reviewing #69464
Background:
* SwiftValue can expose Swift value types (structs/enums)
to ObjC by wrapping them in an Obj-C object on the heap
* SwiftObject is the Obj-C type that Swift class objects all
inherit from (when viewed from Obj-C). This allows arbitrary
Swift class objects to be passed into Obj-C.
History:
* PR #4124 made Obj-C `-hash` and `-isEqual:` work for SwiftValue for Hashable Swift types
* PR #68720 extended SwiftValue to also support Equatable Swift types
* PR #69464 added similar support to SwiftObject
In the process of working through #69464, we found a better way
to handle an ObjC request for `-hash` for a type that is Swift
Equatable but not Hashable. This PR updates SwiftValue to use
the same approach. The approach considers three cases:
1. A Hashable type can forward both `-hash` and `-isEqual:` to
the Swift object.
2. A type that is neither Equatable nor Hashable can implement
`-isEqual:` as the identity check and `-hash` as returning
the address of the object in memory.
3. A type is that Equatable but not Hashable is more complex.
In this last case, we can easily forward `-isEqual:` to the
Equatable conformance but ObjC also requires us to
always provide a compatible `-hash` implementation.
The only way to do this is to have `-hash` return a constant,
but that is a very bad idea in general, so we're also including
a log message whenever we see a request for `-hash` on
a Swift value that is Equatable but not Hashable.
To limit performance problems from the logging itself, we
emit the log message only once for each type.
This is worth telling people about:
Since we're being asked for the hash value, that probably means someone is
trying to put this object into some form of set or dictionary. But we don't know
anything about the Equatable implementation, so the only valid hash value we can
possibly return is a constant. And hash table implementations typically degrade
into unsorted lists when provided constant hash values.
Note: In order to avoid hammering the logs, we only emit the
warning once for each class that hits this path.
There's no need for fatalError() to try to generate its own backtraces
when the runtime's backtracer is enabled. Not only is the code it uses
more fragile but it also doesn't support async or inline frames and it
can't look-up symbols properly either.
rdar://117470489
For an Equatable type, we need a hash implementation that
is compatible with any possible definition of `==`.
Conservatively, that means `-hash` must return a constant.
For non-Equatable types, we know that `==` is identity based,
so we can get better hash behavior by using the object address.
Caveat: This means that non-Equatable types will do two
protocol conformance checks on every call to `hash`.
Add a `SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE` CMake option. When set to true, swift_retain/release and the other functions in InstrumentsSupport.h can be overridden by setting the appropriate global function pointer, as is already the case. When set to false, those function pointers are removed and the functions always go into the default implementation.
Set `SWIFT_STDLIB_OVERRIDABLE_RETAIN_RELEASE` to false when building the minimal stdlib, and set it to true otherwise by default.
rdar://115987924
