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//===--- SimplifyCheckedCast.swift ----------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2024 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
import AST
extension CheckedCastAddrBranchInst : OnoneSimplifiable {
func simplify(_ context: SimplifyContext) {
guard let castWillSucceed = self.dynamicCastResult else {
return
}
if castWillSucceed {
// TODO: handle cases where the operand address types are different.
if source.type == destination.type {
replaceSuccess(context)
}
} else {
replaceFailure(context)
}
}
}
private extension CheckedCastAddrBranchInst {
func replaceSuccess(_ context: SimplifyContext) {
let builder = Builder(before: self, context)
switch consumptionKind {
case .TakeAlways, .TakeOnSuccess:
builder.createCopyAddr(from: source, to: destination, takeSource: true, initializeDest: true)
case .CopyOnSuccess:
builder.createCopyAddr(from: source, to: destination, takeSource: false, initializeDest: true)
}
builder.createBranch(to: successBlock)
context.erase(instruction: self)
}
func replaceFailure(_ context: SimplifyContext) {
let builder = Builder(before: self, context)
switch consumptionKind {
case .TakeAlways:
builder.createDestroyAddr(address: source)
case .CopyOnSuccess, .TakeOnSuccess:
break
}
builder.createBranch(to: failureBlock)
context.erase(instruction: self)
}
}
extension UnconditionalCheckedCastInst : Simplifiable, SILCombineSimplifiable {
func simplify(_ context: SimplifyContext) {
tryOptimizeCastToExistentialMetatype(context)
}
}
private extension UnconditionalCheckedCastInst {
// Replace
// %1 = unconditional_checked_cast %0 : $@thick T.Type to any P.Type
// with
// %1 = init_existential_metatype %0 : $@thick S.Type, $@thick any P.Type
// if type T conforms to protocol P.
// Note that init_existential_metatype is better than unconditional_checked_cast because it does not need
// to do any runtime casting.
func tryOptimizeCastToExistentialMetatype(_ context: SimplifyContext) {
guard targetFormalType.isExistentialMetatype, sourceFormalType.isMetatype else {
return
}
let instanceTy = targetFormalType.instanceTypeOfMetatype
guard let nominal = instanceTy.nominal,
let proto = nominal as? ProtocolDecl
else {
return
}
let conformance = sourceFormalType.instanceTypeOfMetatype.checkConformance(to: proto)
guard conformance.isValid,
conformance.matchesActorIsolation(in: parentFunction)
else {
return
}
let builder = Builder(before: self, context)
let iemt = builder.createInitExistentialMetatype(metatype: operand.value, existentialType: self.type, conformances: [conformance])
self.replace(with: iemt, context)
}
}
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