Merge pull request #19480 from DougGregor/mangled-assoc-type-witness

[ABI] Use mangled names for associated type witnesses.

Author: DougGregor

docs/ABI/Mangling.rst

@@ -90,7 +90,7 @@ Globals
   global ::= protocol-conformance 'WI'   // generic protocol witness table instantiation function
   global ::= type protocol-conformance 'WL'   // lazy protocol witness table cache variable
 
-  global ::= protocol-conformance identifier 'Wt' // associated type metadata accessor
+  global ::= protocol-conformance identifier 'Wt' // associated type metadata accessor (HISTORICAL)
   global ::= protocol-conformance assoc-type-list nominal-type 'WT' // associated type witness table accessor
   global ::= type protocol-conformance 'Wl' // lazy protocol witness table accessor
 
@@ -138,7 +138,7 @@ types where the metadata itself has unknown layout.)
 
   global ::= protocol 'TL'               // protocol requirements base descriptor
   global ::= assoc-type-name 'Tl'        // associated type descriptor
-  global ::= assoc-type-name 'TM'        // default associated type witness accessor
+  global ::= assoc-type-name 'TM'        // default associated type witness accessor (HISTORICAL)
   global ::= type assoc-type-path protocol 'Tn' // associated conformance descriptor
   global ::= type assoc-type-path protocol 'TN' // default associated conformance witness accessor
 

include/swift/ABI/Metadata.h

@@ -1700,11 +1700,6 @@ using TargetWitnessTablePointer =
 
 using WitnessTablePointer = TargetWitnessTablePointer<InProcess>;
 
-using AssociatedTypeAccessFunction =
-  SWIFT_CC(swift) MetadataResponse(MetadataRequest request,
-                                  const Metadata *self,
-                                  const WitnessTable *selfConformance);
-
 using AssociatedWitnessTableAccessFunction =
   SWIFT_CC(swift) WitnessTable *(const Metadata *associatedType,
                                  const Metadata *self,
@@ -2013,7 +2008,10 @@ struct TargetGenericWitnessTable {
   /// The amount of private storage to allocate before the address point,
   /// in words. This memory is zeroed out in the instantiated witness table
   /// template.
-  uint16_t WitnessTablePrivateSizeInWords;
+  ///
+  /// The low bit is used to indicate whether this witness table is known
+  /// to require instantiation.
+  uint16_t WitnessTablePrivateSizeInWordsAndRequiresInstantiation;
 
   /// The protocol descriptor. Only used for resilient conformances.
   RelativeIndirectablePointer<ProtocolDescriptor,
@@ -2037,6 +2035,15 @@ struct TargetGenericWitnessTable {
   /// Private data for the instantiator.  Out-of-line so that the rest
   /// of this structure can be constant.
   RelativeDirectPointer<PrivateDataType> PrivateData;
+
+  uint16_t getWitnessTablePrivateSizeInWords() const {
+    return WitnessTablePrivateSizeInWordsAndRequiresInstantiation >> 1;
+  }
+
+  /// Whether the witness table is known to require instantiation.
+  uint16_t requiresInstantiation() const {
+    return WitnessTablePrivateSizeInWordsAndRequiresInstantiation & 0x01;
+  }
 };
 using GenericWitnessTable = TargetGenericWitnessTable<InProcess>;
 
@@ -2238,8 +2245,7 @@ struct TargetProtocolConformanceDescriptor final
 public:
   using WitnessTableAccessorFn
     = const TargetWitnessTable<Runtime> *(const TargetMetadata<Runtime>*,
-                                          const TargetWitnessTable<Runtime> **,
-                                          size_t);
+                                          const TargetWitnessTable<Runtime> **);
 
   using GenericRequirementDescriptor =
     TargetGenericRequirementDescriptor<Runtime>;

include/swift/ABI/MetadataValues.h

@@ -580,6 +580,19 @@ class ProtocolRequirementFlags {
   bool isInstance() const { return Value & IsInstanceMask; }
 
   int_type getIntValue() const { return Value; }
+
+  enum : uintptr_t {
+    /// Bit used to indicate that an associated type witness is a pointer to
+    /// a mangled name (vs. a pointer to metadata).
+    AssociatedTypeMangledNameBit = 0x01,
+  };
+
+  enum : uint8_t {
+    /// Prefix byte used to identify an associated type whose mangled name
+    /// is relative to the protocol's context rather than the conforming
+    /// type's context.
+    AssociatedTypeInProtocolContextByte = 0xFF
+  };
 };
 
 /// Flags that go in a TargetConformanceDescriptor structure.

include/swift/IRGen/Linking.h

@@ -218,11 +218,6 @@ class LinkEntity {
     /// is stored in the data.
     DefaultAssociatedConformanceAccessor,
 
-    /// A function which returns the default type metadata for the associated
-    /// type of a protocol.  The secondary pointer is a ProtocolDecl*.
-    /// The index of the associated type declaration is stored in the data.
-    DefaultAssociatedTypeMetadataAccessFunction,
-
     /// A SIL function. The pointer is a SILFunction*.
     SILFunction,
 
@@ -263,11 +258,6 @@ class LinkEntity {
     /// A list of key/value pairs that resiliently specify a witness table.
     ResilientProtocolWitnessTable,
 
-    /// A function which returns the type metadata for the associated type
-    /// of a protocol.  The secondary pointer is a ProtocolConformance*.
-    /// The index of the associated type declaration is stored in the data.
-    AssociatedTypeMetadataAccessFunction,
-
     /// A function which returns the witness table for a protocol-constrained
     /// associated type of a protocol.  The secondary pointer is a
     /// ProtocolConformance*.  The index of the associated conformance
@@ -336,7 +326,7 @@ class LinkEntity {
   }
 
   static bool isDeclKind(Kind k) {
-    return k <= Kind::DefaultAssociatedTypeMetadataAccessFunction;
+    return k <= Kind::DefaultAssociatedConformanceAccessor;
   }
   static bool isTypeKind(Kind k) {
     return k >= Kind::ProtocolWitnessTableLazyAccessFunction;
@@ -810,24 +800,6 @@ class LinkEntity {
     return entity;
   }
 
-  static LinkEntity
-  forAssociatedTypeMetadataAccessFunction(const ProtocolConformance *C,
-                                          AssociatedType association) {
-    LinkEntity entity;
-    entity.setForProtocolConformanceAndAssociatedType(
-                     Kind::AssociatedTypeMetadataAccessFunction, C,
-                     association.getAssociation());
-    return entity;
-  }
-
-  static LinkEntity
-  forDefaultAssociatedTypeMetadataAccessFunction(AssociatedType association) {
-    LinkEntity entity;
-    entity.setForDecl(Kind::DefaultAssociatedTypeMetadataAccessFunction,
-                      association.getAssociation());
-    return entity;
-  }
-
   static LinkEntity
   forAssociatedTypeWitnessTableAccessFunction(const ProtocolConformance *C,
                                      const AssociatedConformance &association) {
@@ -925,12 +897,7 @@ class LinkEntity {
   }
 
   AssociatedTypeDecl *getAssociatedType() const {
-    if (getKind() == Kind::AssociatedTypeMetadataAccessFunction)
-      return getAssociatedTypeByIndex(getProtocolConformance(),
-                              LINKENTITY_GET_FIELD(Data, AssociatedTypeIndex));
-
-    assert(getKind() == Kind::AssociatedTypeDescriptor ||
-           getKind() == Kind::DefaultAssociatedTypeMetadataAccessFunction);
+    assert(getKind() == Kind::AssociatedTypeDescriptor);
     return reinterpret_cast<AssociatedTypeDecl *>(Pointer);
   }
 

include/swift/Runtime/Metadata.h

@@ -410,6 +410,20 @@ swift_getGenericWitnessTable(GenericWitnessTable *genericTable,
                              const Metadata *type,
                              void **const *instantiationArgs);
 
+/// Retrieve an associated type witness from the given witness table.
+///
+/// \param wtable The witness table.
+/// \param conformingType Metadata for the conforming type.
+/// \param assocType Associated type descriptor.
+///
+/// \returns metadata for the associated type witness.
+SWIFT_RUNTIME_EXPORT
+MetadataResponse swift_getAssociatedTypeWitness(
+                                          MetadataRequest request,
+                                          WitnessTable *wtable,
+                                          const Metadata *conformingType,
+                                          const ProtocolRequirement *assocType);
+
 /// \brief Fetch a uniqued metadata for a function type.
 SWIFT_RUNTIME_EXPORT
 const FunctionTypeMetadata *

include/swift/Runtime/RuntimeFunctions.def

@@ -645,6 +645,19 @@ FUNCTION(GetGenericWitnessTable, swift_getGenericWitnessTable, C_CC,
               WitnessTablePtrPtrTy),
          ATTRS(NoUnwind, ReadOnly))
 
+// MetadataResponse swift_getAssociatedTypeWitness(
+//                                            MetadataRequest request,
+//                                            WitnessTable *wtable,
+//                                            const Metadata *conformingType,
+//                                            ProtocolRequirement *assocType);
+FUNCTION(GetAssociatedTypeWitness, swift_getAssociatedTypeWitness, C_CC,
+         RETURNS(TypeMetadataResponseTy),
+         ARGS(SizeTy,
+              WitnessTablePtrTy,
+              TypeMetadataPtrTy,
+              ProtocolRequirementStructTy->getPointerTo()),
+         ATTRS(NoUnwind, ReadNone))
+
 // Metadata *swift_getMetatypeMetadata(Metadata *instanceTy);
 FUNCTION(GetMetatypeMetadata, swift_getMetatypeMetadata, C_CC,
          RETURNS(TypeMetadataPtrTy),

lib/IRGen/GenDecl.cpp

@@ -3685,7 +3685,7 @@ llvm::StructType *IRGenModule::getGenericWitnessTableCacheTy() {
     {
       // WitnessTableSizeInWords
       Int16Ty,
-      // WitnessTablePrivateSizeInWords
+      // WitnessTablePrivateSizeInWords + RequiresInstantiation bit
       Int16Ty,
       // Protocol
       RelativeAddressTy,
@@ -3804,27 +3804,6 @@ IRGenModule::getAddrOfWitnessTablePattern(const NormalProtocolConformance *conf,
                                WitnessTableTy, DebugTypeInfo());
 }
 
-llvm::Function *
-IRGenModule::getAddrOfAssociatedTypeMetadataAccessFunction(
-                                  const NormalProtocolConformance *conformance,
-                                  AssociatedType association) {
-  auto forDefinition = ForDefinition;
-
-  LinkEntity entity =
-    LinkEntity::forAssociatedTypeMetadataAccessFunction(conformance,
-                                                        association);
-  llvm::Function *&entry = GlobalFuncs[entity];
-  if (entry) {
-    if (forDefinition) updateLinkageForDefinition(*this, entry, entity);
-    return entry;
-  }
-
-  auto signature = getAssociatedTypeMetadataAccessFunctionSignature();
-  LinkInfo link = LinkInfo::get(*this, entity, forDefinition);
-  entry = createFunction(*this, link, signature);
-  return entry;
-}
-
 llvm::Function *
 IRGenModule::getAddrOfAssociatedTypeWitnessTableAccessFunction(
                                   const NormalProtocolConformance *conformance,
@@ -3846,25 +3825,6 @@ IRGenModule::getAddrOfAssociatedTypeWitnessTableAccessFunction(
   return entry;
 }
 
-llvm::Function *
-IRGenModule::getAddrOfDefaultAssociatedTypeMetadataAccessFunction(
-                                  AssociatedType association) {
-  auto forDefinition = ForDefinition;
-
-  LinkEntity entity =
-    LinkEntity::forDefaultAssociatedTypeMetadataAccessFunction(association);
-  llvm::Function *&entry = GlobalFuncs[entity];
-  if (entry) {
-    if (forDefinition) updateLinkageForDefinition(*this, entry, entity);
-    return entry;
-  }
-
-  auto signature = getAssociatedTypeMetadataAccessFunctionSignature();
-  LinkInfo link = LinkInfo::get(*this, entity, forDefinition);
-  entry = createFunction(*this, link, signature);
-  return entry;
-}
-
 llvm::Function *
 IRGenModule::getAddrOfDefaultAssociatedConformanceAccessor(
                                          AssociatedConformance requirement) {

lib/IRGen/GenMeta.cpp

@@ -457,7 +457,8 @@ namespace {
 
     void addExtendedContext() {
       auto string = IGM.getTypeRef(
-          E->getSelfInterfaceType()->getCanonicalType());
+          E->getSelfInterfaceType()->getCanonicalType(),
+          MangledTypeRefRole::Metadata);
       B.addRelativeAddress(string);
     }
 
@@ -602,7 +603,6 @@ namespace {
       auto var = cast<llvm::GlobalVariable>(addr);
 
       var->setConstant(true);
-      disableAddressSanitizer(IGM, var);
       IGM.setTrueConstGlobal(var);
     }
 
@@ -765,51 +765,16 @@ namespace {
             entry.getAssociatedTypeWitness().Requirement != assocType)
           continue;
 
-        auto witness = entry.getAssociatedTypeWitness().Witness;
-        return getDefaultAssociatedTypeMetadataAccessFunction(
-                 AssociatedType(assocType), witness);
+        auto witness =
+          entry.getAssociatedTypeWitness().Witness->mapTypeOutOfContext()
+            ->getCanonicalType();
+        return IGM.getAssociatedTypeWitness(witness,
+                                            /*inProtocolContext=*/true);
       }
 
       return nullptr;
     }
 
-    /// Create an associated type metadata access function for the default
-    /// associated type witness.
-    llvm::Constant *getDefaultAssociatedTypeMetadataAccessFunction(
-                      AssociatedType requirement, CanType witness) {
-      auto accessor =
-        IGM.getAddrOfDefaultAssociatedTypeMetadataAccessFunction(requirement);
-
-      IRGenFunction IGF(IGM, accessor);
-      if (IGM.DebugInfo)
-        IGM.DebugInfo->emitArtificialFunction(IGF, accessor);
-
-      Explosion parameters = IGF.collectParameters();
-      auto request = DynamicMetadataRequest(parameters.claimNext());
-
-      llvm::Value *self = parameters.claimNext();
-      llvm::Value *wtable = parameters.claimNext();
-
-      CanType selfInContext =
-          Proto->mapTypeIntoContext(Proto->getProtocolSelfType())
-            ->getCanonicalType();
-
-      // Bind local Self type data from the metadata argument.
-      IGF.bindLocalTypeDataFromTypeMetadata(selfInContext, IsExact, self,
-                                            MetadataState::Abstract);
-      IGF.setUnscopedLocalTypeData(
-          selfInContext,
-          LocalTypeDataKind::forAbstractProtocolWitnessTable(Proto),
-          wtable);
-
-      // Emit a reference to the type metadata.
-      auto response = IGF.emitTypeMetadataRef(witness, request);
-      response.ensureDynamicState(IGF);
-      auto returnValue = response.combine(IGF);
-      IGF.Builder.CreateRet(returnValue);
-      return accessor;
-    }
-
     llvm::Constant *findDefaultAssociatedConformanceWitness(
                                                   CanType association,
                                                   ProtocolDecl *requirement) {
@@ -4237,7 +4202,8 @@ GenericRequirementsMetadata irgen::addGenericRequirements(
 
       auto flags = GenericRequirementFlags(abiKind, false, false);
       auto typeName =
-        IGM.getTypeRef(requirement.getSecondType()->getCanonicalType());
+        IGM.getTypeRef(requirement.getSecondType()->getCanonicalType(),
+                       MangledTypeRefRole::Metadata);
 
       addGenericRequirement(IGM, B, metadata, sig, flags,
                             requirement.getFirstType(),