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//===--- ReachableBlocks.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
/// A utility for finding reachable and unreachable blocks.
///
/// Reachable blocks are all blocks which are reachable from the entry block of
/// the function. All other blocks are dead blocks.
struct ReachableBlocks : CustomStringConvertible, NoReflectionChildren {
private var worklist: BasicBlockWorklist
private var function: Function
init(function: Function, _ context: FunctionPassContext) {
self.function = function
self.worklist = BasicBlockWorklist(context)
worklist.pushIfNotVisited(function.entryBlock)
// Propagate lifeness down the control flow.
while let block = worklist.pop() {
worklist.pushIfNotVisited(contentsOf: block.successors)
}
}
func isReachable(block: BasicBlock) -> Bool {
return worklist.hasBeenPushed(block)
}
var description: String {
let blockNames = function.blocks.filter(isReachable).map(\.name)
return "[" + blockNames.joined(separator: ",") + "]"
}
/// TODO: once we have move-only types, make this a real deinit.
mutating func deinitialize() {
worklist.deinitialize()
}
}
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