Merge pull request swiftlang#73645 from eeckstein/pointer-keypath-opt

Improve debug performance of `UnsafePointer.pointer(to:)`

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyKeyPath.swift

@@ -34,6 +34,7 @@ fileprivate func allUsesRemovable(instruction: Instruction) -> Bool {
       switch use.instruction {
       case is UpcastInst,
            is DestroyValueInst,
+           is StrongReleaseInst,
            is BeginBorrowInst,
            is EndBorrowInst,
            is MoveValueInst,

stdlib/public/core/UnsafePointer.swift

@@ -444,16 +444,14 @@ extension UnsafePointer {
   /// - Returns: A pointer to the stored property represented
   ///            by the key path, or `nil`.
   @_alwaysEmitIntoClient
-  #if $Embedded
   @_transparent
-  #endif
   public func pointer<Property>(
     to property: KeyPath<Pointee, Property>
   ) -> UnsafePointer<Property>? {
     guard let o = property._storedInlineOffset else { return nil }
     _internalInvariant(o >= 0)
     _debugPrecondition(
-      o == 0 || UnsafeRawPointer(self) < UnsafeRawPointer(bitPattern: 0 &- o)!,
+      !UInt(bitPattern: self).addingReportingOverflow(UInt(bitPattern: o)).overflow,
       "Overflow in pointer arithmetic"
     )
     return .init(Builtin.gepRaw_Word(_rawValue, o._builtinWordValue))
@@ -1332,16 +1330,14 @@ extension UnsafeMutablePointer {
   /// - Returns: A pointer to the stored property represented
   ///            by the key path, or `nil`.
   @_alwaysEmitIntoClient
-  #if $Embedded
   @_transparent
-  #endif
   public func pointer<Property>(
     to property: KeyPath<Pointee, Property>
   ) -> UnsafePointer<Property>? {
     guard let o = property._storedInlineOffset else { return nil }
     _internalInvariant(o >= 0)
     _debugPrecondition(
-      o == 0 || UnsafeRawPointer(self) < UnsafeRawPointer(bitPattern: 0 &- o)!,
+      !UInt(bitPattern: self).addingReportingOverflow(UInt(bitPattern: o)).overflow,
       "Overflow in pointer arithmetic"
     )
     return .init(Builtin.gepRaw_Word(_rawValue, o._builtinWordValue))
@@ -1356,16 +1352,14 @@ extension UnsafeMutablePointer {
   /// - Returns: A mutable pointer to the stored property represented
   ///            by the key path, or `nil`.
   @_alwaysEmitIntoClient
-  #if $Embedded
   @_transparent
-  #endif
   public func pointer<Property>(
     to property: WritableKeyPath<Pointee, Property>
   ) -> UnsafeMutablePointer<Property>? {
     guard let o = property._storedInlineOffset else { return nil }
     _internalInvariant(o >= 0)
     _debugPrecondition(
-      o == 0 || UnsafeRawPointer(self) < UnsafeRawPointer(bitPattern: 0 &- o)!,
+      !UInt(bitPattern: self).addingReportingOverflow(UInt(bitPattern: o)).overflow,
       "Overflow in pointer arithmetic"
     )
     return .init(Builtin.gepRaw_Word(_rawValue, o._builtinWordValue))

test/SILOptimizer/pointer-performance.swift

@@ -0,0 +1,17 @@
+// RUN: %target-swift-frontend %s -module-name=test -parse-as-library -emit-sil | %FileCheck %s
+
+// REQUIRES: swift_stdlib_no_asserts,optimized_stdlib
+
+public struct S {
+  var a: Int
+  var b: Int
+}
+
+// Check that even with -Onone, no keypath is created.
+
+// CHECK-LABEL: sil @$s4test6testitySPySiGSgSPyAA1SVGF :
+// CHECK-NOT:     keypath
+// CHECK:       } // end sil function '$s4test6testitySPySiGSgSPyAA1SVGF'
+public func testit(_ p: UnsafePointer<S>) -> UnsafePointer<Int>? {
+  return p.pointer(to: \.b)
+}

test/SILOptimizer/simplify_keypath.sil

@@ -0,0 +1,47 @@
+// RUN: %target-sil-opt -enable-sil-verify-all %s -onone-simplification -simplify-instruction=keypath | %FileCheck %s
+
+sil_stage canonical
+
+import Builtin
+import Swift
+
+struct S {
+  @_hasStorage var a: Int
+  @_hasStorage var b: Int
+}
+
+// CHECK-LABEL: sil [ossa] @remove_dead_keypath_ossa :
+// CHECK-NOT:     keypath
+// CHECK-NOT:     destroy_value
+// CHECK:         %0 = tuple
+// CHECK-NEXT:    return
+// CHECK:       } // end sil function 'remove_dead_keypath_ossa'
+sil [ossa] @remove_dead_keypath_ossa : $@convention(thin) () -> () {
+bb0:
+  %0 = keypath $WritableKeyPath<S, Int>, (root $S; stored_property #S.b : $Int)
+  %1 = upcast %0 : $WritableKeyPath<S, Int> to $KeyPath<S, Int>
+  %2 = begin_borrow %1 : $KeyPath<S, Int>
+  end_borrow %2 : $KeyPath<S, Int>
+  %4 = copy_value %1 : $KeyPath<S, Int>
+  %5 = move_value %4 : $KeyPath<S, Int>
+  destroy_value %1 : $KeyPath<S, Int>
+  destroy_value %5 : $KeyPath<S, Int>
+  %r = tuple()
+  return %r : $()
+}
+
+// CHECK-LABEL: sil @remove_dead_keypath :
+// CHECK-NOT:     keypath
+// CHECK-NOT:     strong_release
+// CHECK:         %0 = tuple
+// CHECK-NEXT:    return
+// CHECK:       } // end sil function 'remove_dead_keypath'
+sil @remove_dead_keypath : $@convention(thin) () -> () {
+bb0:
+  %0 = keypath $WritableKeyPath<S, Int>, (root $S; stored_property #S.b : $Int)
+  %1 = upcast %0 : $WritableKeyPath<S, Int> to $KeyPath<S, Int>
+  strong_release %1 : $KeyPath<S, Int>
+  %r = tuple()
+  return %r : $()
+}
+