GenericSpecialization: change how new specialized witness tables are added to MandatoryPerformanceOptimization's worklist

Do it by passing a closure instead of returning the new witness table.
This allows to add more than one new witness table to the worklist

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/ModulePasses/MandatoryPerformanceOptimizations.swift

@@ -271,8 +271,9 @@ private func specializeWitnessTables(for initExRef: InitExistentialRefInst, _ co
     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)
+        specializeWitnessTable(forConformance: conformance, errorLocation: initExRef.location, context) {
+          worklist.addWitnessMethods(of: $0)
+        }
       }
     } else if let origWitnessTable {
       checkForGenericMethods(in: origWitnessTable, errorLocation: initExRef.location, context)

SwiftCompilerSources/Sources/Optimizer/Utilities/GenericSpecialization.swift

@@ -78,7 +78,8 @@ func specializeVTablesOfSuperclasses(_ moduleContext: ModulePassContext) {
 
 func specializeWitnessTable(forConformance conformance: Conformance,
                             errorLocation: Location,
-                            _ context: ModulePassContext) -> WitnessTable
+                            _ context: ModulePassContext,
+                            _ notifyNewWitnessTable: (WitnessTable) -> ())
 {
   let genericConformance = conformance.genericConformance
   guard let witnessTable = context.lookupWitnessTable(for: genericConformance) else {
@@ -107,5 +108,7 @@ func specializeWitnessTable(forConformance conformance: Conformance,
     }
     return origEntry
   }
-  return context.createWitnessTable(entries: newEntries, conformance: conformance, linkage: .shared, serialized: false)
+  let newWT = context.createWitnessTable(entries: newEntries,conformance: conformance,
+                                         linkage: .shared, serialized: false)
+  notifyNewWitnessTable(newWT)
 }