Merge pull request #69955 from eeckstein/deinit-devirtualizer

Optimizer: de-virtualize deinits of non-copyable types

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/CMakeLists.txt

@@ -13,6 +13,7 @@ swift_compiler_sources(Optimizer
   ComputeEscapeEffects.swift
   ComputeSideEffects.swift
   DeadStoreElimination.swift
+  DeinitDevirtualizer.swift
   InitializeStaticGlobals.swift
   LetPropertyLowering.swift
   ObjectOutliner.swift

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/DeinitDevirtualizer.swift

@@ -0,0 +1,30 @@
+//===--- DeinitDevirtualizer.swift ----------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import SIL
+
+/// Devirtualizes destroys of non-copyable values.
+///
+let deinitDevirtualizer = FunctionPass(name: "deinit-devirtualizer") {
+  (function: Function, context: FunctionPassContext) in
+
+  for inst in function.instructions {
+    switch inst {
+    case let destroyValue as DestroyValueInst:
+      _ = devirtualizeDeinits(of: destroyValue, context)
+    case let destroyAddr as DestroyAddrInst:
+      _ = devirtualizeDeinits(of: destroyAddr, context)
+    default:
+      break
+    }
+  }
+}

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/InitializeStaticGlobals.swift

@@ -181,7 +181,13 @@ private func getSequenceOfElementStores(firstStore: StoreInst) -> ([StoreInst],
     return nil
   }
   let structAddr = elementAddr.struct
-  let numElements = structAddr.type.getNominalFields(in: firstStore.parentFunction).count
+  if structAddr.type.isMoveOnly {
+    return nil
+  }
+  guard let fields = structAddr.type.getNominalFields(in: firstStore.parentFunction) else {
+    return nil
+  }
+  let numElements = fields.count
   var elementStores = Array<StoreInst?>(repeating: nil, count: numElements)
   var numStoresFound = 0
 

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/ObjCBridgingOptimization.swift

@@ -185,9 +185,9 @@ private func optimizeNonOptionalBridging(_ apply: ApplyInst,
   // empty value.
   // Create the needed blocks of the `switch_enum` CFG diamond.
   let origBlock = bridgeToSwiftCall.parentBlock
-  let someBlock = context.splitBlock(at: bridgeToSwiftCall)
-  let noneBlock = context.splitBlock(at: bridgeToSwiftCall)
-  let continueBlock = context.splitBlock(at: bridgeToSwiftCall)
+  let someBlock = context.splitBlock(before: bridgeToSwiftCall)
+  let noneBlock = context.splitBlock(before: bridgeToSwiftCall)
+  let continueBlock = context.splitBlock(before: bridgeToSwiftCall)
 
 
   let builder = Builder(atEndOf: origBlock, location: bridgeToSwiftCall.location, context)

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/ObjectOutliner.swift

@@ -410,7 +410,7 @@ private extension AllocRefInstBase {
 
   var numClassFields: Int {
     assert(type.isClass)
-    return type.getNominalFields(in: parentFunction).count
+    return type.getNominalFields(in: parentFunction)!.count
   }
 
   var numStoresPerTailElement: Int {
@@ -475,7 +475,7 @@ private func replace(findStringCall: ApplyInst,
                      with cachedFindStringFunc: Function,
                      _ context: FunctionPassContext) {
   let cacheType = cachedFindStringFunc.argumentTypes[2].objectType
-  let wordTy = cacheType.getNominalFields(in: findStringCall.parentFunction)[0]
+  let wordTy = cacheType.getNominalFields(in: findStringCall.parentFunction)![0]
 
   let name = context.mangleOutlinedVariable(from: findStringCall.parentFunction)
 

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/ReleaseDevirtualizer.swift

@@ -167,7 +167,7 @@ private extension Type {
       return true
     }
     if isStruct {
-      return getNominalFields(in: function).containsSingleReference(in: function)
+      return getNominalFields(in: function)?.containsSingleReference(in: function) ?? false
     } else if isTuple {
       return tupleElements.containsSingleReference(in: function)
     } else {

SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyBeginBorrow.swift

@@ -192,7 +192,7 @@ private extension ForwardingInstruction {
         return false
       }
       let structFields = si.struct.type.getNominalFields(in: parentFunction)
-      return structFields.hasSingleNonTrivialElement(at: si.fieldIndex, in: parentFunction)
+      return structFields?.hasSingleNonTrivialElement(at: si.fieldIndex, in: parentFunction) ?? false
     case let ti as TupleExtractInst:
       return ti.tuple.type.tupleElements.hasSingleNonTrivialElement(at: ti.fieldIndex, in: parentFunction)
     default:

SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyLoad.swift

@@ -135,7 +135,10 @@ extension LoadInst : OnoneSimplifyable, SILCombineSimplifyable {
       case let sea as StructElementAddrInst:
         let structType = sea.struct.type
         if structType.nominal.name == "_SwiftArrayBodyStorage" {
-          switch structType.getNominalFields(in: parentFunction).getNameOfField(withIndex: sea.fieldIndex) {
+          guard let fields = structType.getNominalFields(in: parentFunction) else {
+            return false
+          }
+          switch fields.getNameOfField(withIndex: sea.fieldIndex) {
           case "count":
             break
           case "_capacityAndFlags":
@@ -153,7 +156,10 @@ extension LoadInst : OnoneSimplifyable, SILCombineSimplifyable {
         case "__RawDictionaryStorage",
               "__RawSetStorage":
           // For Dictionary and Set we support "count" and "capacity".
-          switch classType.getNominalFields(in: parentFunction).getNameOfField(withIndex: rea.fieldIndex) {
+          guard let fields = classType.getNominalFields(in: parentFunction) else {
+            return false
+          }
+          switch fields.getNameOfField(withIndex: rea.fieldIndex) {
           case "_count", "_capacity":
             break
           default:

SwiftCompilerSources/Sources/Optimizer/ModulePasses/MandatoryPerformanceOptimizations.swift

@@ -90,6 +90,16 @@ private func optimize(function: Function, _ context: FunctionPassContext, _ work
           _ = context.specializeClassMethodInst(classMethod)
         }
 
+      // 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) {
+          context.diagnosticEngine.diagnose(destroyValue.location.sourceLoc, .deinit_not_visible)
+        }
+      case let destroyAddr as DestroyAddrInst:
+        if !devirtualizeDeinits(of: destroyAddr, simplifyCtxt) {
+          context.diagnosticEngine.diagnose(destroyAddr.location.sourceLoc, .deinit_not_visible)
+        }
+
       default:
         break
       }

SwiftCompilerSources/Sources/Optimizer/PassManager/Context.swift

@@ -21,6 +21,10 @@ protocol Context {
 extension Context {
   var options: Options { Options(_bridged: _bridged) }
 
+  var diagnosticEngine: DiagnosticEngine {
+    return DiagnosticEngine(bridged: _bridged.getDiagnosticEngine())
+  }
+
   // The calleeAnalysis is not specific to a function and therefore can be provided in
   // all contexts.
   var calleeAnalysis: CalleeAnalysis {
@@ -38,6 +42,10 @@ extension Context {
       default:         fatalError("unhandled SILStage case")
     }
   }
+
+  func lookupDeinit(ofNominal: NominalTypeDecl) -> Function? {
+    _bridged.lookUpNominalDeinitFunction(ofNominal.bridged).function
+  }
 }
 
 /// A context which allows mutation of a function's SIL.
@@ -55,9 +63,24 @@ extension MutatingContext {
   ///
   /// `inst` and all subsequent instructions are moved to the new block, while all
   /// instructions _before_ `inst` remain in the original block.
-  func splitBlock(at inst: Instruction) -> BasicBlock {
+  func splitBlock(before inst: Instruction) -> BasicBlock {
+    notifyBranchesChanged()
+    return _bridged.splitBlockBefore(inst.bridged).block
+  }
+
+  /// Splits the basic block, which contains `inst`, after `inst` and returns the
+  /// new block.
+  ///
+  /// All subsequent instructions after `inst` are moved to the new block, while `inst` and all
+  /// instructions _before_ `inst` remain in the original block.
+  func splitBlock(after inst: Instruction) -> BasicBlock {
+    notifyBranchesChanged()
+    return _bridged.splitBlockAfter(inst.bridged).block
+  }
+
+  func createBlock(after block: BasicBlock) -> BasicBlock {
     notifyBranchesChanged()
-    return _bridged.splitBlock(inst.bridged).block
+    return _bridged.createBlockAfter(block.bridged).block
   }
 
   func erase(instruction: Instruction) {