mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-16 11:30:51 +00:00
784545fba0
Summary: This patch is an attempt at making `DenseMapIterator`s "fail-fast". Fail-fast iterators that have been invalidated due to insertion into the host `DenseMap` deterministically trip an assert (in debug mode) on access, instead of non-deterministically hitting memory corruption issues. Enabling fail-fast iterators breaks the LLVM C++ ABI, so they are predicated on `LLVM_ENABLE_ABI_BREAKING_CHECKS`. `LLVM_ENABLE_ABI_BREAKING_CHECKS` by default flips with `LLVM_ENABLE_ASSERTS`, but can be clamped to ON or OFF using the CMake / autoconf build system. Reviewers: chandlerc, dexonsmith, rnk, zturner Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D8351 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233310 91177308-0d34-0410-b5e6-96231b3b80d8
100 lines
3.2 KiB
C++
100 lines
3.2 KiB
C++
//===- llvm/ADT/EpochTracker.h - ADT epoch tracking --------------*- C++ -*-==//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file defines the DebugEpochBase and DebugEpochBase::HandleBase classes.
|
|
// These can be used to write iterators that are fail-fast when LLVM is built
|
|
// with asserts enabled.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_ADT_EPOCH_TRACKER_H
|
|
#define LLVM_ADT_EPOCH_TRACKER_H
|
|
|
|
#include "llvm/Config/llvm-config.h"
|
|
|
|
#include <cstdint>
|
|
|
|
namespace llvm {
|
|
|
|
#ifndef LLVM_ENABLE_ABI_BREAKING_CHECKS
|
|
|
|
class DebugEpochBase {
|
|
public:
|
|
void incrementEpoch() {}
|
|
|
|
class HandleBase {
|
|
public:
|
|
HandleBase() {}
|
|
explicit HandleBase(const DebugEpochBase *) {}
|
|
bool isHandleInSync() const { return true; }
|
|
const void *getEpochAddress() const { return nullptr; }
|
|
};
|
|
};
|
|
|
|
#else
|
|
|
|
/// \brief A base class for data structure classes wishing to make iterators
|
|
/// ("handles") pointing into themselves fail-fast. When building without
|
|
/// asserts, this class is empty and does nothing.
|
|
///
|
|
/// DebugEpochBase does not by itself track handles pointing into itself. The
|
|
/// expectation is that routines touching the handles will poll on
|
|
/// isHandleInSync at appropriate points to assert that the handle they're using
|
|
/// is still valid.
|
|
///
|
|
class DebugEpochBase {
|
|
uint64_t Epoch;
|
|
|
|
public:
|
|
DebugEpochBase() : Epoch(0) {}
|
|
|
|
/// \brief Calling incrementEpoch invalidates all handles pointing into the
|
|
/// calling instance.
|
|
void incrementEpoch() { ++Epoch; }
|
|
|
|
/// \brief The destructor calls incrementEpoch to make use-after-free bugs
|
|
/// more likely to crash deterministically.
|
|
~DebugEpochBase() { incrementEpoch(); }
|
|
|
|
/// \brief A base class for iterator classes ("handles") that wish to poll for
|
|
/// iterator invalidating modifications in the underlying data structure.
|
|
/// When LLVM is built without asserts, this class is empty and does nothing.
|
|
///
|
|
/// HandleBase does not track the parent data structure by itself. It expects
|
|
/// the routines modifying the data structure to call incrementEpoch when they
|
|
/// make an iterator-invalidating modification.
|
|
///
|
|
class HandleBase {
|
|
const uint64_t *EpochAddress;
|
|
uint64_t EpochAtCreation;
|
|
|
|
public:
|
|
HandleBase() : EpochAddress(nullptr), EpochAtCreation(UINT64_MAX) {}
|
|
|
|
explicit HandleBase(const DebugEpochBase *Parent)
|
|
: EpochAddress(&Parent->Epoch), EpochAtCreation(Parent->Epoch) {}
|
|
|
|
/// \brief Returns true if the DebugEpochBase this Handle is linked to has
|
|
/// not called incrementEpoch on itself since the creation of this
|
|
/// HandleBase instance.
|
|
bool isHandleInSync() const { return *EpochAddress == EpochAtCreation; }
|
|
|
|
/// \brief Returns a pointer to the epoch word stored in the data structure
|
|
/// this handle points into. Can be used to check if two iterators point
|
|
/// into the same data structure.
|
|
const void *getEpochAddress() const { return EpochAddress; }
|
|
};
|
|
};
|
|
|
|
#endif // LLVM_ENABLE_ABI_BREAKING_CHECKS
|
|
|
|
} // namespace llvm
|
|
|
|
#endif
|