Merge pull request swiftlang#84739 from atrick/lifedep-unsafeaddress

LifetimeDependenceDefUseWalker: store to unsafeMutableAddress

Author: atrick

SwiftCompilerSources/Sources/AST/Type.swift

@@ -147,15 +147,8 @@ extension TypeProperties {
   public var isDynamicSelf: Bool { rawType.bridged.isDynamicSelf()}
   public var isBox: Bool { rawType.bridged.isBox() }
 
-  /// True if this is the type which represents an integer literal used in a type position.
-  /// For example `N` in `struct T<let N: Int> {}`
-  public var isInteger: Bool { rawType.bridged.isInteger() }
-
   public var canBeClass: Type.TraitResult { rawType.bridged.canBeClass().result }
 
-  /// True if this the nominal type `Swift.Optional`.
-  public var isOptional: Bool { rawType.bridged.isOptional() }
-
   /// True if this type is a value type (struct/enum) that defines a `deinit`.
   public var isValueTypeWithDeinit: Bool {
     if let nominal = nominal, nominal.valueTypeDestructor != nil {
@@ -164,6 +157,34 @@ extension TypeProperties {
     return false
   }
 
+  //===--------------------------------------------------------------------===//
+  //                      Checks for stdlib types
+  //===--------------------------------------------------------------------===//
+
+  /// True if this is the type which represents an integer literal used in a type position.
+  /// For example `N` in `struct T<let N: Int> {}`
+  public var isInteger: Bool { rawType.bridged.isInteger() }
+
+  /// True if this the nominal type `Swift.Optional`.
+  public var isOptional: Bool { rawType.bridged.isOptional() }
+
+  /// A non-nil result type implies isUnsafe[Raw][Mutable]Pointer. A raw
+  /// pointer has a `void` element type.
+  public var unsafePointerElementType: Type? {
+    Type(bridgedOrNil: rawType.bridged.getAnyPointerElementType())
+  }
+
+  public var isAnyUnsafePointer: Bool {
+    unsafePointerElementType != nil
+  }
+
+  public var isAnyUnsafeBufferPointer: Bool {
+    rawType.bridged.isUnsafeBufferPointerType()
+      || rawType.bridged.isUnsafeMutableBufferPointerType()
+      || rawType.bridged.isUnsafeRawBufferPointerType()
+      || rawType.bridged.isUnsafeMutableRawBufferPointerType()
+  }
+
   //===--------------------------------------------------------------------===//
   //                Properties of lowered `SILFunctionType`s
   //===--------------------------------------------------------------------===//

SwiftCompilerSources/Sources/Optimizer/Utilities/LifetimeDependenceUtils.swift

@@ -862,7 +862,7 @@ extension LifetimeDependenceDefUseWalker {
     return walkDownUses(of: value, using: operand)
   }    
 
-  // copy_addr
+  // copy_addr %operand to %address; %_newAddr = mark_dependence %address on %operand
   mutating func loadedAddressUse(of operand: Operand, intoAddress address: Operand) -> WalkResult {
     if leafUse(of: operand) == .abortWalk {
       return .abortWalk
@@ -971,7 +971,29 @@ extension LifetimeDependenceDefUseWalker {
       break
     case .yield:
       return storeToYieldDependence(address: address, of: operand)
-    case .global, .class, .tail, .storeBorrow, .pointer, .index, .unidentified:
+    case let .pointer(p2a):
+      if !address.isEscapable, let base = p2a.isResultOfUnsafeAddressor() {
+        let selfValue = base.value
+        if selfValue.type.isAddress {
+          // Normally an unsafeMutableAddressor is mutating, so this is the common case (address-type
+          // 'selfValue'). Treat the store to this pointer-to-address projection just like any store to the local
+          // variable holding 'selfValue'.
+          return visitStoredUses(of: operand, into: selfValue)
+        }
+        // selfValue.type might not an be address:
+        // (1) mark_dependence on unsafeAddress is handled like a storedUse
+        // (2) nonmutating unsafeMutableAddress (e.g. UnsafeMutable[Buffer]Pointer).
+        // A nonmutating unsafeMutableAddress is only expected to happen for UnsafeMutable[Buffer]Pointer, in which case
+
+        // If selfValue is trivial (UnsafeMutable[Buffer]Pointer), its uses can be ignored.
+        if selfValue.type.isTrivial(in: selfValue.parentFunction) {
+          return .continueWalk
+        }
+        // Otherwise a store to indirect memory is conservatively escaping.
+        return escapingDependence(on: operand)
+      }
+      break
+    case .global, .class, .tail, .storeBorrow, .index, .unidentified:
       // An address produced by .storeBorrow should never be stored into.
       //
       // TODO: allow storing an immortal value into a global.
@@ -1045,7 +1067,7 @@ extension LifetimeDependenceDefUseWalker {
       }
     case .dependenceDest:
       // Simply a marker that indicates the start of an in-memory dependent value. If this was a mark_dependence, uses
-      // of its forwarded address has were visited by LocalVariableAccessWalker and recorded as separate local accesses.
+      // of its forwarded address were visited by LocalVariableAccessWalker and recorded as separate local accesses.
       return .continueWalk
     case .store, .storeBorrow:
       // A store does not use the previous in-memory value.

SwiftCompilerSources/Sources/SIL/Function.swift

@@ -52,6 +52,8 @@ final public class Function : CustomStringConvertible, HasShortDescription, Hash
 
   public var isConvertPointerToPointerArgument: Bool { bridged.isConvertPointerToPointerArgument() }
 
+  public var isAddressor: Bool { bridged.isAddressor() }
+
   public var specializationLevel: Int { bridged.specializationLevel() }
 
   public var isSpecialization: Bool { bridged.isSpecialization() }

SwiftCompilerSources/Sources/SIL/Utilities/AccessUtils.swift

@@ -512,6 +512,22 @@ public extension PointerToAddressInst {
     }
     return nil
   }
+
+  // If this address is the result of a call to unsafe[Mutable]Address, return the 'self' operand of the apply. This
+  // represents the base value into which this address projects.
+  func isResultOfUnsafeAddressor() -> Operand? {
+    if isStrict,
+       let extract = pointer as? StructExtractInst,
+       extract.`struct`.type.isAnyUnsafePointer,
+       let addressorApply = extract.`struct` as? ApplyInst,
+       let addressorFunc = addressorApply.referencedFunction,
+       addressorFunc.isAddressor
+    {
+      let selfArgIdx = addressorFunc.selfArgumentIndex!
+      return addressorApply.argumentOperands[selfArgIdx]
+    }
+    return nil
+  }
 }
 
 /// TODO: migrate AccessBase to use this instead of GlobalVariable because many utilities need to get back to a

include/swift/AST/ASTBridging.h

@@ -2955,6 +2955,11 @@ struct BridgedASTType {
   BRIDGED_INLINE bool isBuiltinFixedWidthInteger(SwiftInt width) const;
   BRIDGED_INLINE bool isOptional() const;
   BRIDGED_INLINE bool isBuiltinType() const;
+  SWIFT_IMPORT_UNSAFE BRIDGED_INLINE BridgedASTType getAnyPointerElementType() const;
+  BRIDGED_INLINE bool isUnsafeBufferPointerType() const;
+  BRIDGED_INLINE bool isUnsafeMutableBufferPointerType() const;
+  BRIDGED_INLINE bool isUnsafeRawBufferPointerType() const;
+  BRIDGED_INLINE bool isUnsafeMutableRawBufferPointerType() const;
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE OptionalBridgedDeclObj getNominalOrBoundGenericNominal() const;
   BRIDGED_INLINE TraitResult canBeClass() const;
   SWIFT_IMPORT_UNSAFE BRIDGED_INLINE OptionalBridgedDeclObj getAnyNominal() const;

include/swift/AST/ASTBridgingImpl.h

@@ -566,6 +566,26 @@ bool BridgedASTType::isBuiltinType() const {
   return unbridged()->isBuiltinType();
 }
 
+BridgedASTType BridgedASTType::getAnyPointerElementType() const {
+  return {unbridged()->getCanonicalType()->getAnyPointerElementType().getPointer()};
+}
+
+bool BridgedASTType::isUnsafeBufferPointerType() const {
+  return unbridged()->isUnsafeBufferPointer();
+}
+
+bool BridgedASTType::isUnsafeMutableBufferPointerType() const {
+  return unbridged()->isUnsafeMutableBufferPointer();
+}
+
+bool BridgedASTType::isUnsafeRawBufferPointerType() const {
+  return unbridged()->isUnsafeRawBufferPointer();
+}
+
+bool BridgedASTType::isUnsafeMutableRawBufferPointerType() const {
+  return unbridged()->isUnsafeMutableRawBufferPointer();
+}
+
 OptionalBridgedDeclObj BridgedASTType::getNominalOrBoundGenericNominal() const {
   return {unbridged()->getNominalOrBoundGenericNominal()};
 }

include/swift/SIL/SILBridging.h

@@ -562,6 +562,7 @@ struct BridgedFunction {
   BRIDGED_INLINE bool isSpecialization() const;
   bool isTrapNoReturn() const;
   bool isConvertPointerToPointerArgument() const;
+  bool isAddressor() const;
   bool isAutodiffVJP() const;
   SwiftInt specializationLevel() const;
   SWIFT_IMPORT_UNSAFE BridgedSubstitutionMap getMethodSubstitutions(BridgedSubstitutionMap contextSubs,

lib/SILOptimizer/Utils/OptimizerBridging.cpp

@@ -511,6 +511,13 @@ bool BridgedFunction::isConvertPointerToPointerArgument() const {
   return false;
 }
 
+bool BridgedFunction::isAddressor() const {
+  if (auto declRef = dyn_cast_or_null<AccessorDecl>(getFunction()->getDeclRef().getDecl())) {
+    return declRef->isAnyAddressor();
+  }
+  return false;
+}
+
 bool BridgedFunction::isAutodiffVJP() const {
   return swift::isDifferentiableFuncComponent(
       getFunction(), swift::AutoDiffFunctionComponent::VJP);