mirror of
https://github.com/wpilibsuite/allwpilib
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d90cf843e8
This is a breaking change to dependencies that use the static ntcore library. Unless the wpiutil library is also linked, linker errors will result. This does not affect the shared ntcore library.
98 lines
3.2 KiB
C++
98 lines
3.2 KiB
C++
//===- llvm/ADT/EpochTracker.h - ADT epoch tracking --------------*- C++ -*-==//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the DebugEpochBase and DebugEpochBase::HandleBase classes.
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// These can be used to write iterators that are fail-fast when LLVM is built
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// with asserts enabled.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_EPOCH_TRACKER_H
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#define LLVM_ADT_EPOCH_TRACKER_H
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#include <cstdint>
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namespace llvm {
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#ifdef NDEBUG //ifndef LLVM_ENABLE_ABI_BREAKING_CHECKS
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class DebugEpochBase {
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public:
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void incrementEpoch() {}
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class HandleBase {
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public:
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HandleBase() = default;
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explicit HandleBase(const DebugEpochBase *) {}
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bool isHandleInSync() const { return true; }
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const void *getEpochAddress() const { return nullptr; }
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};
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};
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#else
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/// \brief A base class for data structure classes wishing to make iterators
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/// ("handles") pointing into themselves fail-fast. When building without
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/// asserts, this class is empty and does nothing.
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///
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/// DebugEpochBase does not by itself track handles pointing into itself. The
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/// expectation is that routines touching the handles will poll on
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/// isHandleInSync at appropriate points to assert that the handle they're using
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/// is still valid.
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///
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class DebugEpochBase {
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uint64_t Epoch;
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public:
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DebugEpochBase() : Epoch(0) {}
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/// \brief Calling incrementEpoch invalidates all handles pointing into the
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/// calling instance.
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void incrementEpoch() { ++Epoch; }
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/// \brief The destructor calls incrementEpoch to make use-after-free bugs
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/// more likely to crash deterministically.
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~DebugEpochBase() { incrementEpoch(); }
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/// \brief A base class for iterator classes ("handles") that wish to poll for
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/// iterator invalidating modifications in the underlying data structure.
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/// When LLVM is built without asserts, this class is empty and does nothing.
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///
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/// HandleBase does not track the parent data structure by itself. It expects
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/// the routines modifying the data structure to call incrementEpoch when they
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/// make an iterator-invalidating modification.
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///
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class HandleBase {
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const uint64_t *EpochAddress;
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uint64_t EpochAtCreation;
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public:
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HandleBase() : EpochAddress(nullptr), EpochAtCreation(UINT64_MAX) {}
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explicit HandleBase(const DebugEpochBase *Parent)
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: EpochAddress(&Parent->Epoch), EpochAtCreation(Parent->Epoch) {}
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/// \brief Returns true if the DebugEpochBase this Handle is linked to has
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/// not called incrementEpoch on itself since the creation of this
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/// HandleBase instance.
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bool isHandleInSync() const { return *EpochAddress == EpochAtCreation; }
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/// \brief Returns a pointer to the epoch word stored in the data structure
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/// this handle points into. Can be used to check if two iterators point
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/// into the same data structure.
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const void *getEpochAddress() const { return EpochAddress; }
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};
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};
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#endif // LLVM_ENABLE_ABI_BREAKING_CHECKS
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} // namespace llvm
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#endif
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