Merge pull request #82890 from meg-gupta/simplifyendcowaddr

Add simplification for end_cow_mutation_addr

Author: meg-gupta

SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/CMakeLists.txt

@@ -24,6 +24,7 @@ swift_compiler_sources(Optimizer
   SimplifyDebugStep.swift
   SimplifyDestroyValue.swift
   SimplifyDestructure.swift
+  SimplifyEndCOWMutationAddr.swift
   SimplifyFixLifetime.swift
   SimplifyGlobalValue.swift
   SimplifyInitEnumDataAddr.swift

SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyEndCOWMutationAddr.swift

@@ -0,0 +1,32 @@
+//===--- SimplifyEndCOWMutationAddr.swift ---------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2025 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
+
+// Simplify end_cow_mutation_addr to end_cow_mutation when it's operand is loadable
+extension EndCOWMutationAddrInst: OnoneSimplifiable, SILCombineSimplifiable {
+  func simplify(_ context: SimplifyContext) {
+    let address = operand.value
+    if !address.type.isLoadable(in: parentFunction) {
+      return
+    }
+    if address.type.isTrivial(in: parentFunction) {
+      context.erase(instruction: self)
+      return
+    }
+    let builder = Builder(before: self, context)
+    let load = builder.createLoad(fromAddress: address, ownership: parentFunction.hasOwnership ? .take : .unqualified)
+    let endCOWMutation = builder.createEndCOWMutation(instance: load, keepUnique: false) 
+    builder.createStore(source: endCOWMutation, destination: address, ownership: parentFunction.hasOwnership ? .initialize : .unqualified)
+    context.erase(instruction: self)
+  }
+}

SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyMisc.swift

@@ -30,3 +30,4 @@ extension TypeValueInst: OnoneSimplifiable, SILCombineSimplifiable {
     context.erase(instruction: self)
   }
 }
+

SwiftCompilerSources/Sources/Optimizer/PassManager/PassRegistration.swift

@@ -136,6 +136,7 @@ private func registerSwiftPasses() {
   registerForSILCombine(AllocStackInst.self,        { run(AllocStackInst.self, $0) })
   registerForSILCombine(ApplyInst.self,             { run(ApplyInst.self, $0) })
   registerForSILCombine(TryApplyInst.self,          { run(TryApplyInst.self, $0) })
+  registerForSILCombine(EndCOWMutationAddrInst.self, { run(EndCOWMutationAddrInst.self, $0) })
 
   // Test passes
   registerPass(aliasInfoDumper, { aliasInfoDumper.run($0) })

lib/IRGen/LoadableByAddress.cpp

@@ -3984,6 +3984,14 @@ class AssignAddressToDef : SILInstructionVisitor<AssignAddressToDef> {
     singleValueInstructionFallback(kp);
   }
 
+  void visitEndCOWMutationInst(EndCOWMutationInst *endCOW) {
+    // This instruction is purely for semantic tracking in SIL.
+    // Simply forward the value and delete the instruction.
+    auto valAddr = assignment.getAddressForValue(endCOW->getOperand());
+    assignment.mapValueToAddress(endCOW, valAddr);
+    assignment.markForDeletion(endCOW);
+  }
+
   void visitMarkDependenceInst(MarkDependenceInst *mark) {
     // This instruction is purely for semantic tracking in SIL.
     // Simply forward the value and delete the instruction.

lib/SILOptimizer/SILCombiner/Simplifications.def

@@ -52,6 +52,7 @@ INSTRUCTION_SIMPLIFICATION(TypeValueInst)
 INSTRUCTION_SIMPLIFICATION(UncheckedAddrCastInst)
 INSTRUCTION_SIMPLIFICATION(UncheckedEnumDataInst)
 INSTRUCTION_SIMPLIFICATION(WitnessMethodInst)
+INSTRUCTION_SIMPLIFICATION(EndCOWMutationAddrInst)
 INSTRUCTION_SIMPLIFICATION_WITH_LEGACY(AllocStackInst)
 INSTRUCTION_SIMPLIFICATION_WITH_LEGACY(UnconditionalCheckedCastInst)
 INSTRUCTION_SIMPLIFICATION_WITH_LEGACY(ApplyInst)

test/SILOptimizer/simplify_end_cow_mutation_addr.sil

@@ -0,0 +1,45 @@
+// RUN: %target-sil-opt %s -onone-simplification -simplify-instruction=end_cow_mutation_addr -enable-experimental-feature Lifetimes | %FileCheck %s
+
+// REQUIRES: swift_feature_Lifetimes
+
+import Swift
+import Builtin
+
+protocol P {
+  mutating func getMutableSpan() -> MutableSpan<Int>
+}
+
+struct C : P {
+  @_hasStorage var array: [Int] { get set }
+  mutating func getMutableSpan() -> MutableSpan<Int>
+  init(array: [Int])
+}
+
+extension Array : P where Element == Int {
+  mutating func getMutableSpan() -> MutableSpan<Int>
+}
+
+sil @getMutableSpan : $@convention(method) (@inout Array<Int>) -> @lifetime(borrow 0) @owned MutableSpan<Int>
+sil @write : $@convention(thin) (@lifetime(copy 0) @inout MutableSpan<Int>) -> ()
+
+// CHECK-LABEL: sil hidden @test_end_cow_mutation_addr :
+// CHECK-NOT: end_cow_mutation_addr
+// CHECK: end_cow_mutation
+// CHECK:       } // end sil function 'test_end_cow_mutation_addr'
+sil hidden @test_end_cow_mutation_addr : $@convention(thin) (@inout C) -> () {
+bb0(%0 : $*C):
+  %3 = alloc_stack [lexical] [var_decl] $MutableSpan<Int>, var, name "span"
+  %5 = struct_element_addr %0, #C.array
+  %6 = function_ref @getMutableSpan : $@convention(method) (@inout Array<Int>) -> @lifetime(borrow 0) @owned MutableSpan<Int>
+  %7 = apply %6(%5) : $@convention(method) (@inout Array<Int>) -> @lifetime(borrow 0) @owned MutableSpan<Int>
+  %8 = mark_dependence [nonescaping] %7 on %0
+  %9 = mark_dependence [nonescaping] %8 on %0
+  %10 = mark_dependence [nonescaping] %9 on %0
+  store %10 to %3
+  %12 = function_ref @write : $@convention(thin) (@lifetime(copy 0) @inout MutableSpan<Int>) -> ()
+  %13 = apply %12(%3) : $@convention(thin) (@lifetime(copy 0) @inout MutableSpan<Int>) -> ()
+  end_cow_mutation_addr %0
+  dealloc_stack %3
+  %17 = tuple ()
+  return %17
+}