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Swift Optimizer: add a simplification for pointer_to_address
For a redundant pair of pointer-address conversions, e.g. %2 = address_to_pointer %1 %3 = pointer_to_address %2 [strict] replace all uses of %3 with %1.
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‎SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/CMakeLists.txt

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@@ -19,6 +19,7 @@ swift_compiler_sources(Optimizer
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SimplifyInitEnumDataAddr.swift
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SimplifyLoad.swift
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SimplifyPartialApply.swift
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SimplifyPointerToAddress.swift
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SimplifyRefCasts.swift
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SimplifyRetainReleaseValue.swift
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SimplifyStrongRetainRelease.swift

‎SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyPointerToAddress.swift

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//===--- SimplifyPointerToAddress.swift -----------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import SIL
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extension PointerToAddressInst : OnoneSimplifyable {
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/// For a redundant pair of pointer-address conversions, e.g.
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///
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/// %2 = address_to_pointer %1
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/// %3 = pointer_to_address %2 [strict]
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///
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/// replace all uses of %3 with %1.
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///
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func simplify(_ context: SimplifyContext) {
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if let atp = self.pointer as? AddressToPointerInst,
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atp.address.type == self.type,
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self.isStrict,
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// If the pointer is within an ownership scope, the transformation can break ownership rules, e.g.
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// %2 = begin_borrow %1
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// %3 = ref_tail_addr %2
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// %4 = address_to_pointer %3
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// end_borrow %2
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// %5 = pointer_to_address %4 <- cannot replace %5 with %3!
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//
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!atp.address.accessBase.hasLocalOwnershipLifetime
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{
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self.uses.replaceAll(with: atp.address, context)
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}
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}
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}

‎SwiftCompilerSources/Sources/SIL/Instruction.swift

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@@ -457,6 +457,7 @@ class AddressToPointerInst : SingleValueInstruction, UnaryInstruction {
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final public
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class PointerToAddressInst : SingleValueInstruction, UnaryInstruction {
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public var pointer: Value { operand.value }
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public var isStrict: Bool { bridged.PointerToAddressInst_isStrict() }
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}
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final public

‎include/swift/SIL/SILBridging.h

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@@ -546,6 +546,9 @@ struct BridgedInstruction {
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return getAs<swift::BuiltinInst>()->getSubstitutions();
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}
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bool PointerToAddressInst_isStrict() const {
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return getAs<swift::PointerToAddressInst>()->isStrict();
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}
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bool AddressToPointerInst_needsStackProtection() const {
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return getAs<swift::AddressToPointerInst>()->needsStackProtection();

‎test/SILOptimizer/simplify_pointer_to_address.sil

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// RUN: %target-sil-opt -enable-sil-verify-all %s -onone-simplification -simplify-instruction=pointer_to_address | %FileCheck %s
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// REQUIRES: swift_in_compiler
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sil_stage canonical
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import Builtin
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import Swift
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import SwiftShims
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class C {}
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// CHECK-LABEL: sil @remove_conversion :
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// CHECK-NOT: address_to_pointer
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// CHECK-NOT: pointer_to_address
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// CHECK: [[L:%.*]] = load %0
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// CHECK: return [[L]]
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// CHECK: } // end sil function 'remove_conversion'
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sil @remove_conversion : $@convention(thin) (@in Int) -> Int {
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bb0(%0 : $*Int):
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%1 = address_to_pointer %0 : $*Int to $Builtin.RawPointer
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%2 = pointer_to_address %1 : $Builtin.RawPointer to [strict] $*Int
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%3 = load %2 : $*Int
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return %3 : $Int
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}
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// CHECK-LABEL: sil @mismatching_type :
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// CHECK: address_to_pointer
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// CHECK: [[A:%.*]] = pointer_to_address
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// CHECK: [[L:%.*]] = load [[A]]
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// CHECK: return [[L]]
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// CHECK: } // end sil function 'mismatching_type'
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sil @mismatching_type : $@convention(thin) (@in Int) -> Bool {
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bb0(%0 : $*Int):
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%1 = address_to_pointer %0 : $*Int to $Builtin.RawPointer
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%2 = pointer_to_address %1 : $Builtin.RawPointer to [strict] $*Bool
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%3 = load %2 : $*Bool
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return %3 : $Bool
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}
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// CHECK-LABEL: sil @no_strict :
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// CHECK: address_to_pointer
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// CHECK: [[A:%.*]] = pointer_to_address
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// CHECK: [[L:%.*]] = load [[A]]
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// CHECK: return [[L]]
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// CHECK: } // end sil function 'no_strict'
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sil @no_strict : $@convention(thin) (@in Int) -> Int {
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bb0(%0 : $*Int):
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%1 = address_to_pointer %0 : $*Int to $Builtin.RawPointer
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%2 = pointer_to_address %1 : $Builtin.RawPointer to $*Int
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%3 = load %2 : $*Int
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return %3 : $Int
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}
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// CHECK-LABEL: sil [ossa] @borrow_escape :
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// CHECK: address_to_pointer
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// CHECK: [[A:%.*]] = pointer_to_address
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// CHECK: [[L:%.*]] = load [trivial] [[A]]
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// CHECK: return [[L]]
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// CHECK: } // end sil function 'borrow_escape'
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sil [ossa] @borrow_escape : $@convention(thin) (@guaranteed C) -> Int {
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bb0(%0 : @guaranteed $C):
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%1 = begin_borrow %0 : $C
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%2 = ref_tail_addr %1: $C, $Int
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%3 = address_to_pointer %2 : $*Int to $Builtin.RawPointer
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end_borrow %1 : $C
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%5 = pointer_to_address %3 : $Builtin.RawPointer to [strict] $*Int
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%6 = load [trivial] %5 : $*Int
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return %6 : $Int
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}
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sil @createC : $@convention(thin) () -> @owned C
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// CHECK-LABEL: sil @non_ossa_local_ownership :
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// CHECK: [[A:%.*]] = ref_tail_addr
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// CHECK-NOT: address_to_pointer
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// CHECK-NOT: pointer_to_address
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// CHECK: [[L:%.*]] = load [[A]]
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// CHECK: return [[L]]
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// CHECK: } // end sil function 'non_ossa_local_ownership'
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sil @non_ossa_local_ownership : $@convention(thin) () -> Int {
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bb0:
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%f = function_ref @createC : $@convention(thin) () -> @owned C
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%0 = apply %f() : $@convention(thin) () -> @owned C
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%2 = ref_tail_addr %0: $C, $Int
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%3 = address_to_pointer %2 : $*Int to $Builtin.RawPointer
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%5 = pointer_to_address %3 : $Builtin.RawPointer to [strict] $*Int
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%6 = load %5 : $*Int
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strong_release %0 : $C
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return %6 : $Int
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}
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