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//===--- SimplifyRetainReleaseValue.swift ---------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2023 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
extension RetainValueInst : Simplifyable, SILCombineSimplifyable {
func simplify(_ context: SimplifyContext) {
// Remove pairs of
// ```
// release_value %0 // the release is before the retain!
// retain_value %0
// ```
// which sometimes the ARC optimizations cannot do.
//
if optimizeReleaseRetainPair(context) {
return
}
// Replace
// ```
// %1 = enum #E.A, %0
// retain_value %1
// ```
// with
// ```
// %1 = enum #E.A, %0 // maybe dead
// retain_value %0
// ```
replaceOperandWithPayloadOfEnum(context)
// Remove if the operand is trivial (but not necessarily its type), e.g.
// ```
// %1 = value_to_bridge_object %0 : $UInt64
// retain_value %1 : $Builtin.BridgeObject
// ```
if removeIfOperandIsTrivial(context) {
return
}
// Replace e.g.
// ```
// retain_value %1 : $SomeClass
// ```
// with
// ```
// strong_retain %1 : $SomeClass
// ```
replaceWithStrongOrUnownedRetain(context)
}
}
extension ReleaseValueInst : Simplifyable, SILCombineSimplifyable {
func simplify(_ context: SimplifyContext) {
// Replace
// ```
// %1 = enum #E.A, %0
// release_value %1
// ```
// with
// ```
// %1 = enum #E.A, %0 // maybe dead
// release_value %0
// ```
replaceOperandWithPayloadOfEnum(context)
// Remove if the operand is trivial (but not necessarily its type), e.g.
// ```
// %1 = value_to_bridge_object %0 : $UInt64
// release_value %1 : $Builtin.BridgeObject
// ```
if removeIfOperandIsTrivial(context) {
return
}
// Replace e.g.
// ```
// release_value %1 : $SomeClass
// ```
// with
// ```
// release_value %1 : $SomeClass
// ```
replaceWithStrongOrUnownedRelease(context)
}
}
private extension RetainValueInst {
func optimizeReleaseRetainPair(_ context: SimplifyContext) -> Bool {
if let prevInst = self.previous,
let release = prevInst as? ReleaseValueInst,
release.value == self.value {
context.erase(instruction: release)
context.erase(instruction: self)
return true
}
return false
}
func replaceWithStrongOrUnownedRetain(_ context: SimplifyContext) {
if value.type.isReferenceCounted(in: parentFunction) {
let builder = Builder(before: self, context)
if value.type.isUnownedStorageType {
builder.createUnownedRetain(operand: value)
} else {
builder.createStrongRetain(operand: value)
}
context.erase(instruction: self)
}
}
}
private extension ReleaseValueInst {
func replaceWithStrongOrUnownedRelease(_ context: SimplifyContext) {
if value.type.isReferenceCounted(in: parentFunction) {
let builder = Builder(before: self, context)
if value.type.isUnownedStorageType {
builder.createUnownedRelease(operand: value)
} else {
builder.createStrongRelease(operand: value)
}
context.erase(instruction: self)
}
}
}
private extension UnaryInstruction {
func replaceOperandWithPayloadOfEnum(_ context: SimplifyContext) {
if let e = operand.value as? EnumInst,
!e.type.isValueTypeWithDeinit,
let payload = e.payload {
operand.set(to: payload, context)
}
}
func removeIfOperandIsTrivial(_ context: SimplifyContext) -> Bool {
if operand.value.isTrivial(context) {
context.erase(instruction: self)
return true
}
return false
}
}
|
