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54 lines
1.5 KiB
C++
54 lines
1.5 KiB
C++
//===--- BasicBlockUtils.h - Utilities for SILBasicBlock -------*- C++ -*-===//
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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 - 2017 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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#ifndef SWIFT_SIL_DEADENDBLOCKS_H
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#define SWIFT_SIL_DEADENDBLOCKS_H
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#include "llvm/ADT/SetVector.h"
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namespace swift {
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class SILFunction;
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class SILBasicBlock;
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/// A utility for finding dead-end blocks.
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///
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/// Dead-end blocks are blocks from which there is no path to the function exit
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/// (either return or throw). These are blocks which end with an unreachable
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/// instruction and blocks from which all paths end in "unreachable" blocks.
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/// This utility is needed to determine if the a value definition can have a
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/// lack of users ignored along a specific path.
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class DeadEndBlocks {
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llvm::SetVector<const SILBasicBlock *> ReachableBlocks;
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const SILFunction *F;
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bool isComputed = false;
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void compute();
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public:
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DeadEndBlocks(const SILFunction *F) : F(F) {}
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/// Returns true if \p BB is a dead-end block.
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bool isDeadEnd(SILBasicBlock *BB) {
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if (!isComputed) {
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// Lazily compute the dataflow.
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compute();
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isComputed = true;
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}
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return ReachableBlocks.count(BB) == 0;
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}
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};
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} // namespace swift
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#endif
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