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[ADT][CMake][AutoConf] Fail-fast iterators for DenseMap

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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
This commit is contained in:
Sanjoy Das
2015-03-26 19:25:01 +00:00
parent 55a5cb1a4d
commit 784545fba0
11 changed files with 241 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

63
include/llvm/ADT/DenseMap.h
View File

@@ -15,6 +15,7 @@
#define LLVM_ADT_DENSEMAP_H
#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/EpochTracker.h"
#include "llvm/Support/AlignOf.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/MathExtras.h"
@@ -50,7 +51,7 @@ class DenseMapIterator;
template <typename DerivedT, typename KeyT, typename ValueT, typename KeyInfoT,
typename BucketT>
class DenseMapBase {
class DenseMapBase : public DebugEpochBase {
public:
typedef unsigned size_type;
typedef KeyT key_type;
@@ -62,16 +63,17 @@ public:
const_iterator;
inline iterator begin() {
// When the map is empty, avoid the overhead of AdvancePastEmptyBuckets().
return empty() ? end() : iterator(getBuckets(), getBucketsEnd());
return empty() ? end() : iterator(getBuckets(), getBucketsEnd(), *this);
}
inline iterator end() {
return iterator(getBucketsEnd(), getBucketsEnd(), true);
return iterator(getBucketsEnd(), getBucketsEnd(), *this, true);
}
inline const_iterator begin() const {
return empty() ? end() : const_iterator(getBuckets(), getBucketsEnd());
return empty() ? end()
: const_iterator(getBuckets(), getBucketsEnd(), *this);
}
inline const_iterator end() const {
return const_iterator(getBucketsEnd(), getBucketsEnd(), true);
return const_iterator(getBucketsEnd(), getBucketsEnd(), *this, true);
}
bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const {
@@ -81,11 +83,13 @@ public:
/// Grow the densemap so that it has at least Size buckets. Does not shrink
void resize(size_type Size) {
incrementEpoch();
if (Size > getNumBuckets())
grow(Size);
}
void clear() {
incrementEpoch();
if (getNumEntries() == 0 && getNumTombstones() == 0) return;
// If the capacity of the array is huge, and the # elements used is small,
@@ -118,13 +122,13 @@ public:
iterator find(const KeyT &Val) {
BucketT *TheBucket;
if (LookupBucketFor(Val, TheBucket))
return iterator(TheBucket, getBucketsEnd(), true);
return iterator(TheBucket, getBucketsEnd(), *this, true);
return end();
}
const_iterator find(const KeyT &Val) const {
const BucketT *TheBucket;
if (LookupBucketFor(Val, TheBucket))
return const_iterator(TheBucket, getBucketsEnd(), true);
return const_iterator(TheBucket, getBucketsEnd(), *this, true);
return end();
}
@@ -137,14 +141,14 @@ public:
iterator find_as(const LookupKeyT &Val) {
BucketT *TheBucket;
if (LookupBucketFor(Val, TheBucket))
return iterator(TheBucket, getBucketsEnd(), true);
return iterator(TheBucket, getBucketsEnd(), *this, true);
return end();
}
template<class LookupKeyT>
const_iterator find_as(const LookupKeyT &Val) const {
const BucketT *TheBucket;
if (LookupBucketFor(Val, TheBucket))
return const_iterator(TheBucket, getBucketsEnd(), true);
return const_iterator(TheBucket, getBucketsEnd(), *this, true);
return end();
}
@@ -163,12 +167,13 @@ public:
std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
BucketT *TheBucket;
if (LookupBucketFor(KV.first, TheBucket))
return std::make_pair(iterator(TheBucket, getBucketsEnd(), true),
return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
false); // Already in map.
// Otherwise, insert the new element.
TheBucket = InsertIntoBucket(KV.first, KV.second, TheBucket);
return std::make_pair(iterator(TheBucket, getBucketsEnd(), true), true);
return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
true);
}
// Inserts key,value pair into the map if the key isn't already in the map.
@@ -177,14 +182,15 @@ public:
std::pair<iterator, bool> insert(std::pair<KeyT, ValueT> &&KV) {
BucketT *TheBucket;
if (LookupBucketFor(KV.first, TheBucket))
return std::make_pair(iterator(TheBucket, getBucketsEnd(), true),
return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
false); // Already in map.
// Otherwise, insert the new element.
TheBucket = InsertIntoBucket(std::move(KV.first),
std::move(KV.second),
TheBucket);
return std::make_pair(iterator(TheBucket, getBucketsEnd(), true), true);
return std::make_pair(iterator(TheBucket, getBucketsEnd(), *this, true),
true);
}
/// insert - Range insertion of pairs.
@@ -431,6 +437,8 @@ private:
}
BucketT *InsertIntoBucketImpl(const KeyT &Key, BucketT *TheBucket) {
incrementEpoch();
// If the load of the hash table is more than 3/4, or if fewer than 1/8 of
// the buckets are empty (meaning that many are filled with tombstones),
// grow the table.
@@ -987,9 +995,10 @@ private:
template <typename KeyT, typename ValueT, typename KeyInfoT, typename Bucket,
bool IsConst>
class DenseMapIterator {
class DenseMapIterator : DebugEpochBase::HandleBase {
typedef DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, true> ConstIterator;
friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, true>;
friend class DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, false>;
public:
typedef ptrdiff_t difference_type;
@@ -1003,8 +1012,10 @@ private:
public:
DenseMapIterator() : Ptr(nullptr), End(nullptr) {}
DenseMapIterator(pointer Pos, pointer E, bool NoAdvance = false)
: Ptr(Pos), End(E) {
DenseMapIterator(pointer Pos, pointer E, const DebugEpochBase &Epoch,
bool NoAdvance = false)
: DebugEpochBase::HandleBase(&Epoch), Ptr(Pos), End(E) {
assert(isHandleInSync() && "invalid construction!");
if (!NoAdvance) AdvancePastEmptyBuckets();
}
@@ -1015,28 +1026,40 @@ public:
typename = typename std::enable_if<!IsConstSrc && IsConst>::type>
DenseMapIterator(
const DenseMapIterator<KeyT, ValueT, KeyInfoT, Bucket, IsConstSrc> &I)
: Ptr(I.Ptr), End(I.End) {}
: DebugEpochBase::HandleBase(I), Ptr(I.Ptr), End(I.End) {}
reference operator*() const {
assert(isHandleInSync() && "invalid iterator access!");
return *Ptr;
}
pointer operator->() const {
assert(isHandleInSync() && "invalid iterator access!");
return Ptr;
}
bool operator==(const ConstIterator &RHS) const {
return Ptr == RHS.operator->();
assert((!Ptr || isHandleInSync()) && "handle not in sync!");
assert((!RHS.Ptr || RHS.isHandleInSync()) && "handle not in sync!");
assert(getEpochAddress() == RHS.getEpochAddress() &&
"comparing incomparable iterators!");
return Ptr == RHS.Ptr;
}
bool operator!=(const ConstIterator &RHS) const {
return Ptr != RHS.operator->();
assert((!Ptr || isHandleInSync()) && "handle not in sync!");
assert((!RHS.Ptr || RHS.isHandleInSync()) && "handle not in sync!");
assert(getEpochAddress() == RHS.getEpochAddress() &&
"comparing incomparable iterators!");
return Ptr != RHS.Ptr;
}
inline DenseMapIterator& operator++() { // Preincrement
assert(isHandleInSync() && "invalid iterator access!");
++Ptr;
AdvancePastEmptyBuckets();
return *this;
}
DenseMapIterator operator++(int) { // Postincrement
assert(isHandleInSync() && "invalid iterator access!");
DenseMapIterator tmp = *this; ++*this; return tmp;
}