Optimizer: replace explicit_copy_value and explicit_copy_addr with their non-explicit counterparts

The `explicit_copy_value` and `explicit_copy_addr` instructions are only used for non-copyable diagnostics in the mandatory pipeline.
After that we can replace them by their non-explicit counterparts so that optimizations (which only know of `copy_value` and `copy_addr`) can do their work.

rdar://159039552

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/CMakeLists.txt

@@ -25,6 +25,7 @@ swift_compiler_sources(Optimizer
   SimplifyDestroyValue.swift
   SimplifyDestructure.swift
   SimplifyEndCOWMutationAddr.swift
+  SimplifyExplicitCopy.swift
   SimplifyFixLifetime.swift
   SimplifyGlobalValue.swift
   SimplifyInitEnumDataAddr.swift

SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyExplicitCopy.swift

@@ -0,0 +1,64 @@
+//===--- SimplifyExplicitCopy.swift ---------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 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
+
+// The `explicit_copy_value` and `explicit_copy_addr` instructions are only used for non-copyable
+// diagnostics in the mandatory pipeline. After that we can replace them by their non-explicit counterparts
+// so that optimizations (which only know of `copy_value` and `copy_addr`) can do their work.
+
+/// Replaces
+///
+/// ```
+///   %1 = explicit_copy_value %0
+/// ```
+/// ->
+/// ```
+///   %1 = copy_value %0
+/// ```
+///
+extension ExplicitCopyValueInst : Simplifiable, SILCombineSimplifiable {
+  func simplify(_ context: SimplifyContext) {
+    if context.silStage == .raw {
+      // Make sure we don't remove `explicit_copy_value` in the diagnostic pipeline.
+      return
+    }
+
+    let builder = Builder(before: self, context)
+    let copyValue = builder.createCopyValue(operand: fromValue)
+    replace(with: copyValue, context)
+  }
+}
+
+/// Replaces
+///
+/// ```
+///   explicit_copy_addr %0 to %1
+/// ```
+/// ->
+/// ```
+///   copy_addr %0 to %1
+/// ```
+///
+extension ExplicitCopyAddrInst : Simplifiable, SILCombineSimplifiable {
+  func simplify(_ context: SimplifyContext) {
+    if context.silStage == .raw {
+      // Make sure we don't remove `explicit_copy_addr` in the diagnostic pipeline.
+      return
+    }
+
+    let builder = Builder(before: self, context)
+    builder.createCopyAddr(from: source, to: destination,
+                           takeSource: isTakeOfSource, initializeDest: isInitializationOfDestination)
+    context.erase(instruction: self)
+  }
+}

lib/SILOptimizer/SILCombiner/Simplifications.def

@@ -32,6 +32,8 @@
 INSTRUCTION_SIMPLIFICATION(BeginBorrowInst)
 INSTRUCTION_SIMPLIFICATION(BeginCOWMutationInst)
 INSTRUCTION_SIMPLIFICATION(ClassifyBridgeObjectInst)
+INSTRUCTION_SIMPLIFICATION(ExplicitCopyAddrInst)
+INSTRUCTION_SIMPLIFICATION(ExplicitCopyValueInst)
 INSTRUCTION_SIMPLIFICATION(FixLifetimeInst)
 INSTRUCTION_SIMPLIFICATION(GlobalValueInst)
 INSTRUCTION_SIMPLIFICATION(StrongRetainInst)

test/SILOptimizer/simplify_explicit_copy_addr.sil

@@ -0,0 +1,38 @@
+// RUN: %target-sil-opt -enable-sil-verify-all %s -onone-simplification -simplify-instruction=explicit_copy_addr | %FileCheck %s --check-prefix=CHECK-ONONE --check-prefix=CHECK
+// RUN: %target-sil-opt -enable-sil-verify-all %s -simplification -simplify-instruction=explicit_copy_addr | %FileCheck %s --check-prefix=CHECK-O --check-prefix=CHECK
+
+// REQUIRES: swift_in_compiler
+
+sil_stage canonical
+
+import Swift
+import Builtin
+
+// CHECK-LABEL:      sil [ossa] @simplify_copy_take_init :
+// CHECK:            bb0(%0 : $*String, %1 : $*String):
+// CHECK-O-NEXT:       {{ }}copy_addr [take] %1 to [init] %0
+// CHECK-ONONE-NEXT:   explicit_copy_addr [take] %1 to [init] %0
+// CHECK-NEXT:         %3 = tuple ()
+// CHECK:            } // end sil function 'simplify_copy_take_init'
+sil [ossa] @simplify_copy_take_init : $@convention(thin) (@in String) -> @out String {
+bb0(%0 : $*String, %1 : $*String):
+  explicit_copy_addr [take] %1 to [init] %0
+  %3 = tuple ()
+  return %3
+}
+
+// CHECK-LABEL:      sil [ossa] @simplify_copy_assign :
+// CHECK:            bb0(%0 : $*String, %1 : $*String):
+// CHECK-O-NEXT:       {{ }}copy_addr %1 to %0
+// CHECK-ONONE-NEXT:   explicit_copy_addr %1 to %0
+// CHECK-NEXT:         %3 = tuple ()
+// CHECK:            } // end sil function 'simplify_copy_assign'
+sil [ossa] @simplify_copy_assign : $@convention(thin) (@inout String, @inout String) -> () {
+bb0(%0 : $*String, %1 : $*String):
+  explicit_copy_addr %1 to %0
+  %3 = tuple ()
+  return %3
+}
+
+
+

test/SILOptimizer/simplify_explicit_copy_value.sil

@@ -0,0 +1,21 @@
+// RUN: %target-sil-opt -enable-sil-verify-all %s -onone-simplification -simplify-instruction=explicit_copy_value | %FileCheck %s --check-prefix=CHECK-ONONE --check-prefix=CHECK
+// RUN: %target-sil-opt -enable-sil-verify-all %s -simplification -simplify-instruction=explicit_copy_value | %FileCheck %s --check-prefix=CHECK-O --check-prefix=CHECK
+
+// REQUIRES: swift_in_compiler
+
+sil_stage canonical
+
+import Swift
+import Builtin
+
+// CHECK-LABEL: sil [ossa] @simplify_explicit_copy_value :
+// CHECK-O:       %1 = copy_value %0
+// CHECK-ONONE:   %1 = explicit_copy_value %0
+// CHECK-NEXT:    return %1
+// CHECK:       } // end sil function 'simplify_explicit_copy_value'
+sil [ossa] @simplify_explicit_copy_value : $@convention(thin) (@guaranteed String) -> @owned String {
+bb0(%0 : @guaranteed $String):
+  %1 = explicit_copy_value %0
+  return %1
+}
+