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Implement MultiPayloadEnum support for projectEnumValue (#30635)

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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.
This commit is contained in:
tbkka
2020-03-31 15:12:44 -07:00
committed by GitHub
parent 8d68607681
commit 3c8fde7885
12 changed files with 1110 additions and 554 deletions
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17
include/swift/SwiftRemoteMirror/SwiftRemoteMirror.h
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@@ -241,6 +241,8 @@ int swift_reflection_projectExistential(SwiftReflectionContextRef ContextRef,
///
/// Takes the address and typeref for an enum and determines the
/// index of the currently-selected case within the enum.
/// You can use this index with `swift_reflection_childOfTypeRef`
/// to get detailed information about the specific case.
///
/// Returns true if the enum case could be successfully determined.
/// In particular, note that this code may fail for valid in-memory data
@@ -251,21 +253,6 @@ int swift_reflection_projectEnumValue(SwiftReflectionContextRef ContextRef,
swift_typeref_t EnumTypeRef,
int *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 when you are finished.
SWIFT_REMOTE_MIRROR_LINKAGE
int swift_reflection_getEnumCaseTypeRef(SwiftReflectionContextRef ContextRef,
swift_typeref_t EnumTypeRef,
int CaseIndex,
char **CaseName,
swift_typeref_t *PayloadTypeRef);
/// Dump a brief description of the typeref as a tree to stderr.
SWIFT_REMOTE_MIRROR_LINKAGE
void swift_reflection_dumpTypeRef(swift_typeref_t OpaqueTypeRef);