This code rearchitects and simplifies the projectEnumValue support by
introducing a new `TypeInfo` subclass for each kind of enum, including trivial,
no-payload, single-payload, and three different classes for multi-payload enums:
* "UnsupportedEnum" that we don't understand. This returns "don't know" answers for all requests in cases where the runtime lacks enough information to accurately handle a particular enum.
* MP Enums that only use a separate tag value. This includes generic enums and other dynamic layouts, as well as enums whose payloads have no spare bits.
* MP Enums that use spare bits, possibly in addition to a separate tag. This logic can only be used, of course, if we can in fact compute a spare bit mask that agrees with the compiler.
The final challenge is to choose one of the above three handlings for every MPE. Currently, we do not have an accurate source of information for the spare bit mask, so we never choose the third option above. We use the second option for dynamic MPE layouts (including generics) and the first for everything else.
TODO: Once we can arrange for the compiler to expose spare bit mask data, we'll be able to use that to drive more MPE cases.
Teach RemoteMirror how to project enum values
This adds two new functions to the SwiftRemoteMirror
facility that support inspecting enum values.
Currently, these support non-payload enums and
single-payload enums, including nested enums and
payloads with struct, tuple, and reference payloads.
In particular, it handles nested `Optional` types.
TODO: Multi-payload enums use different strategies for
encoding the cases that aren't yet supported by this
code.
Note: This relies on information from dataLayoutQuery
to correctly decode invalid pointer values that are used
to encode enums. Existing clients will need to augment
their DLQ functions before using these new APIs.
Resolves rdar://59961527
```
/// Projects the value of an enum.
///
/// Takes the address and typeref for an enum and determines the
/// index of the currently-selected case within the enum.
///
/// Returns true iff the enum case could be successfully determined.
/// In particular, note that this code may fail for valid in-memory data
/// if the compiler is using a strategy we do not yet understand.
SWIFT_REMOTE_MIRROR_LINKAGE
int swift_reflection_projectEnumValue(SwiftReflectionContextRef ContextRef,
swift_addr_t EnumAddress,
swift_typeref_t EnumTypeRef,
uint64_t *CaseIndex);
/// Finds information about a particular enum case.
///
/// Given an enum typeref and index of a case, returns:
/// * Typeref of the associated payload or zero if there is no payload
/// * Name of the case if known.
///
/// The Name points to a freshly-allocated C string on the heap. You
/// are responsible for freeing the string (via `free()`) when you are finished.
SWIFT_REMOTE_MIRROR_LINKAGE
int swift_reflection_getEnumCaseTypeRef(SwiftReflectionContextRef ContextRef,
swift_typeref_t EnumTypeRef,
unsigned CaseIndex,
char **CaseName,
swift_typeref_t *PayloadTypeRef);
```
Co-authored-by: Mike Ash <mikeash@apple.com>
PE/COFF does not permit weak linking semantics. This means that the
expression `&symbol == NULL` is tautologically false. In order to
support this semantic, the symbol needs to be dynamically looked up at
runtime. Since the ObjC runtime is not in use on Windows currently,
just ignore this for the time being. Silences a warning from clang
about the tautological comparison.
Also have swift-reflection-test check if the symbol exists. This allows swift-reflection-test to work with older Remote Mirror dylibs that don't have it.
rdar://problem/50030805
Recent Swift uses 2 as the is-Swift bit when running on newer versions, and 1 on older versions. Since it's difficult or impossible to know what we'll be running on at build time, make the selection at runtime.
If one thinks about it, swift's build has two sections: a runtime or target
section (i.e. ./stdlib) and a host section (everything
else). swift-reflection-test is an abberation from that pattern since it is
built for target platforms but is in the section of host tools.
In this commit, I move it into ./stdlib. Beyond being a bitter location
conceptually this will additionally allow me to avoid a dependency cycle in
between the compiler and the stdlib build.
After this, there is only one more target in the compiler code: swift-lang. From
talking with Xi Ge, we can move that into its own separate project as a
package. Once that is done, I will not have any more cycles.
