Merge pull request #76669 from eeckstein/class-existentials

embedded: support class existentials with generic classes

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/DataStructures/FunctionUses.swift

@@ -128,21 +128,21 @@ struct FunctionUses {
 
     for vTable in context.vTables {
       for entry in vTable.entries {
-        markUnknown(entry.function)
+        markUnknown(entry.implementation)
       }
     }
 
     for witnessTable in context.witnessTables {
       for entry in witnessTable.entries {
-        if entry.kind == .Method, let f = entry.methodFunction {
+        if entry.kind == .method, let f = entry.methodFunction {
           markUnknown(f)
         }
       }
     }
 
     for witnessTable in context.defaultWitnessTables {
       for entry in witnessTable.entries {
-        if entry.kind == .Method, let f = entry.methodFunction {
+        if entry.kind == .method, let f = entry.methodFunction {
           markUnknown(f)
         }
       }

SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyRefCasts.swift

@@ -116,7 +116,10 @@ private func insertCompensatingInstructions(for inst: Instruction, in failureBlo
   let newInst: SingleValueInstruction
   switch inst {
   case let ier as InitExistentialRefInst:
-    newInst = builder.createInitExistentialRef(instance: newArg, existentialType: ier.type, useConformancesOf: ier)
+    newInst = builder.createInitExistentialRef(instance: newArg,
+                                               existentialType: ier.type,
+                                               formalConcreteType: ier.formalConcreteType,
+                                               conformances: ier.conformances)
   case let uc as UpcastInst:
     newInst = builder.createUpcast(from: newArg, to: uc.type)
   default:

SwiftCompilerSources/Sources/Optimizer/ModulePasses/MandatoryPerformanceOptimizations.swift

@@ -33,13 +33,23 @@ let mandatoryPerformanceOptimizations = ModulePass(name: "mandatory-performance-
   // For embedded Swift, optimize all the functions (there cannot be any
   // generics, type metadata, etc.)
   if moduleContext.options.enableEmbeddedSwift {
+    // We need to specialize all vtables which are referenced from non-generic contexts. Beside
+    // `alloc_ref`s of generic classes in non-generic functions, we also need to specialize generic
+    // superclasses of non-generic classes. E.g. `class Derived : Base<Int> {}`
+    specializeVTablesOfSuperclasses(moduleContext)
+
     worklist.addAllNonGenericFunctions(of: moduleContext)
   } else {
     worklist.addAllPerformanceAnnotatedFunctions(of: moduleContext)
     worklist.addAllAnnotatedGlobalInitOnceFunctions(of: moduleContext)
   }
 
   optimizeFunctionsTopDown(using: &worklist, moduleContext)
+
+  if moduleContext.options.enableEmbeddedSwift {
+    // Print errors for generic functions in vtables, which is not allowed in embedded Swift.
+    checkVTablesForGenericFunctions(moduleContext)
+  }
 }
 
 private func optimizeFunctionsTopDown(using worklist: inout FunctionWorklist,
@@ -92,17 +102,26 @@ private func optimize(function: Function, _ context: FunctionPassContext, _ modu
       // Embedded Swift specific transformations
       case let alloc as AllocRefInst:
         if context.options.enableEmbeddedSwift {
-          specializeVTableAndAddEntriesToWorklist(for: alloc.type, in: function, context, moduleContext, &worklist)
+          specializeVTableAndAddEntriesToWorklist(for: alloc.type, in: function,
+                                                  errorLocation: alloc.location,
+                                                  moduleContext, &worklist)
         }
       case let metatype as MetatypeInst:
         if context.options.enableEmbeddedSwift {
-          specializeVTableAndAddEntriesToWorklist(for: metatype.type, in: function, context, moduleContext, &worklist)
+          specializeVTableAndAddEntriesToWorklist(for: metatype.type, in: function,
+                                                  errorLocation: metatype.location,
+                                                  moduleContext, &worklist)
         }
       case let classMethod as ClassMethodInst:
         if context.options.enableEmbeddedSwift {
           _ = context.specializeClassMethodInst(classMethod)
         }
 
+      case let initExRef as InitExistentialRefInst:
+        if context.options.enableEmbeddedSwift {
+          specializeWitnessTables(for: initExRef, moduleContext, &worklist)
+        }
+
       // We need to de-virtualize deinits of non-copyable types to be able to specialize the deinitializers.
       case let destroyValue as DestroyValueInst:
         if !devirtualizeDeinits(of: destroyValue, simplifyCtxt) {
@@ -144,19 +163,24 @@ private func optimize(function: Function, _ context: FunctionPassContext, _ modu
 }
 
 private func specializeVTableAndAddEntriesToWorklist(for type: Type, in function: Function,
-                                                     _ context: FunctionPassContext, _ moduleContext: ModulePassContext,
+                                                     errorLocation: Location,
+                                                     _ moduleContext: ModulePassContext,
                                                      _ worklist: inout FunctionWorklist) {
   let vTablesCountBefore = moduleContext.vTables.count
 
-  guard context.specializeVTable(for: type, in: function) != nil else {
+  guard specializeVTable(forClassType: type, errorLocation: errorLocation, moduleContext) != nil else {
     return
   }
 
   // More than one new vtable might have been created (superclasses), process them all
   let vTables = moduleContext.vTables
   for i in vTablesCountBefore ..< vTables.count {
-    for entry in vTables[i].entries {
-      worklist.pushIfNotVisited(entry.function)
+    for entry in vTables[i].entries
+      // A new vtable can still contain a generic function if the method couldn't be specialized for some reason
+      // and an error has been printed. Exclude generic functions to not run into an assert later.
+      where !entry.implementation.isGeneric
+    {
+      worklist.pushIfNotVisited(entry.implementation)
     }
   }
 }
@@ -240,6 +264,45 @@ private func shouldInline(apply: FullApplySite, callee: Function, alreadyInlined
   return false
 }
 
+private func specializeWitnessTables(for initExRef: InitExistentialRefInst, _ context: ModulePassContext,
+                                     _ worklist: inout FunctionWorklist)
+{
+  for conformance in initExRef.conformances where conformance.isConcrete {
+    let origWitnessTable = context.lookupWitnessTable(for: conformance)
+    if conformance.isSpecialized {
+      if origWitnessTable == nil {
+        let wt = specializeWitnessTable(forConformance: conformance, errorLocation: initExRef.location, context)
+        worklist.addWitnessMethods(of: wt)
+      }
+    } else if let origWitnessTable {
+      checkForGenericMethods(in: origWitnessTable, errorLocation: initExRef.location, context)
+    }
+  }
+}
+
+private func checkForGenericMethods(in witnessTable: WitnessTable,
+                                    errorLocation: Location,
+                                    _ context: ModulePassContext)
+{
+  for entry in witnessTable.entries where entry.kind == .method {
+    if let method = entry.methodFunction,
+       method.isGeneric
+    {
+      context.diagnosticEngine.diagnose(errorLocation.sourceLoc, .cannot_specialize_witness_method,
+                                        entry.methodRequirement)
+      return
+    }
+  }
+}
+
+private func checkVTablesForGenericFunctions(_ context: ModulePassContext) {
+  for vTable in context.vTables where !vTable.class.isGenericAtAnyLevel {
+    for entry in vTable.entries where entry.implementation.isGeneric {
+      context.diagnosticEngine.diagnose(entry.methodDecl.location.sourceLoc, .non_final_generic_class_function)
+    }
+  }
+}
+
 private extension FullApplySite {
   func resultIsUsedInGlobalInitialization() -> SmallProjectionPath? {
     guard parentFunction.isGlobalInitOnceFunction,
@@ -445,6 +508,18 @@ fileprivate struct FunctionWorklist {
     }
   }
 
+  mutating func addWitnessMethods(of witnessTable: WitnessTable) {
+    for entry in witnessTable.entries where entry.kind == .method {
+      if let method = entry.methodFunction,
+         // A new witness table can still contain a generic function if the method couldn't be specialized for
+         // some reason and an error has been printed. Exclude generic functions to not run into an assert later.
+         !method.isGeneric
+      {
+        pushIfNotVisited(method)
+      }
+    }
+  }
+
   mutating func pushIfNotVisited(_ element: Function) {
     if pushedFunctions.insert(element).inserted {
       functions.append(element)

SwiftCompilerSources/Sources/Optimizer/PassManager/Context.swift

@@ -61,6 +61,18 @@ extension Context {
     }
   }
 
+  func lookupWitnessTable(for conformance: ProtocolConformance) -> WitnessTable? {
+    return _bridged.lookupWitnessTable(conformance.bridged).witnessTable
+  }
+
+  func lookupVTable(for classDecl: NominalTypeDecl) -> VTable? {
+    return _bridged.lookupVTable(classDecl.bridged).vTable
+  }
+
+  func lookupSpecializedVTable(for classType: Type) -> VTable? {
+    return _bridged.lookupSpecializedVTable(classType.bridged).vTable
+  }
+
   func notifyNewFunction(function: Function, derivedFrom: Function) {
     _bridged.addFunctionToPassManagerWorklist(function.bridged, derivedFrom.bridged)
   }
@@ -221,7 +233,7 @@ extension MutatingContext {
   }
 
   func getContextSubstitutionMap(for type: Type) -> SubstitutionMap {
-    SubstitutionMap(_bridged.getContextSubstitutionMap(type.bridged))
+    SubstitutionMap(bridged: _bridged.getContextSubstitutionMap(type.bridged))
   }
 
   func notifyInstructionsChanged() {
@@ -327,13 +339,6 @@ struct FunctionPassContext : MutatingContext {
     return false
   }
 
-  func specializeVTable(for type: Type, in function: Function) -> VTable? {
-    guard let vtablePtr = _bridged.specializeVTableForType(type.bridged, function.bridged) else {
-      return nil
-    }
-    return VTable(bridged: BridgedVTable(vTable: vtablePtr))
-  }
-
   func specializeClassMethodInst(_ cm: ClassMethodInst) -> Bool {
     if _bridged.specializeClassMethodInst(cm.bridged) {
       notifyInstructionsChanged()

SwiftCompilerSources/Sources/Optimizer/PassManager/ModulePassContext.swift

@@ -54,14 +54,14 @@ struct ModulePassContext : Context, CustomStringConvertible {
   }
 
   struct VTableArray : BridgedRandomAccessCollection {
-    fileprivate let bridged: BridgedPassContext.VTableArray
+    fileprivate let bridgedCtxt: BridgedPassContext
 
     var startIndex: Int { return 0 }
-    var endIndex: Int { return bridged.count }
+    var endIndex: Int { return bridgedCtxt.getNumVTables() }
 
     subscript(_ index: Int) -> VTable {
       assert(index >= startIndex && index < endIndex)
-      return VTable(bridged: BridgedVTable(vTable: bridged.base![index]))
+      return VTable(bridged: bridgedCtxt.getVTable(index))
     }
   }
 
@@ -101,9 +101,7 @@ struct ModulePassContext : Context, CustomStringConvertible {
     GlobalVariableList(first: _bridged.getFirstGlobalInModule().globalVar)
   }
 
-  var vTables: VTableArray {
-    VTableArray(bridged: _bridged.getVTables())
-  }
+  var vTables: VTableArray { VTableArray(bridgedCtxt: _bridged) }
 
   var witnessTables: WitnessTableList {
     WitnessTableList(first: _bridged.getFirstWitnessTableInModule().witnessTable)
@@ -131,6 +129,44 @@ struct ModulePassContext : Context, CustomStringConvertible {
     return function.isDefinition
   }
 
+  func specialize(function: Function, for substitutions: SubstitutionMap) -> Function? {
+    return _bridged.specializeFunction(function.bridged, substitutions.bridged).function
+  }
+
+  enum DeserializationMode {
+    case allFunctions
+    case onlySharedFunctions
+  }
+
+  func deserializeAllCallees(of function: Function, mode: DeserializationMode) {
+    _bridged.deserializeAllCallees(function.bridged, mode == .allFunctions ? true : false)
+  }
+
+  @discardableResult
+  func createWitnessTable(entries: [WitnessTable.Entry],
+                          conformance: ProtocolConformance,
+                          linkage: Linkage,
+                          serialized: Bool) -> WitnessTable
+  {
+    let bridgedEntries = entries.map { $0.bridged }
+    let bridgedWitnessTable = bridgedEntries.withBridgedArrayRef {
+      _bridged.createWitnessTable(linkage.bridged, serialized, conformance.bridged, $0)
+    }
+    return WitnessTable(bridged: bridgedWitnessTable)
+  }
+
+  @discardableResult
+  func createSpecializedVTable(entries: [VTable.Entry],
+                               for classType: Type,
+                               isSerialized: Bool) -> VTable
+  {
+    let bridgedEntries = entries.map { $0.bridged }
+    let bridgedVTable = bridgedEntries.withBridgedArrayRef {
+      _bridged.createSpecializedVTable(classType.bridged, isSerialized, $0)
+    }
+    return VTable(bridged: bridgedVTable)
+  }
+
   func createEmptyFunction(
     name: String,
     parameters: [ParameterInfo],
@@ -176,4 +212,8 @@ extension Function {
   func set(linkage: Linkage, _ context: ModulePassContext) {
     bridged.setLinkage(linkage.bridged)
   }
+
+  func set(isSerialized: Bool, _ context: ModulePassContext) {
+    bridged.setIsSerialized(isSerialized)
+  }
 }

SwiftCompilerSources/Sources/Optimizer/Utilities/CMakeLists.txt

@@ -17,6 +17,7 @@ swift_compiler_sources(Optimizer
   EscapeUtils.swift
   ForwardingUtils.swift
   FunctionSignatureTransforms.swift
+  GenericSpecialization.swift
   LifetimeDependenceUtils.swift
   LocalVariableUtils.swift
   OptUtils.swift

SwiftCompilerSources/Sources/Optimizer/Utilities/DiagnosticEngine.swift

@@ -13,6 +13,7 @@
 import ASTBridging
 
 import Basic
+import SIL
 
 public typealias DiagID = BridgedDiagID
 
@@ -29,6 +30,16 @@ extension Int: DiagnosticArgument {
     fn(BridgedDiagnosticArgument(self))
   }
 }
+extension Type: DiagnosticArgument {
+  public func _withBridgedDiagnosticArgument(_ fn: (BridgedDiagnosticArgument) -> Void) {
+    fn(bridged.asDiagnosticArgument())
+  }
+}
+extension DeclRef: DiagnosticArgument {
+  public func _withBridgedDiagnosticArgument(_ fn: (BridgedDiagnosticArgument) -> Void) {
+    fn(bridged.asDiagnosticArgument())
+  }
+}
 
 public struct DiagnosticFixIt {
   public let start: SourceLoc