[llvm] r279053 - Revert "ADT: Remove UB in ilist (and use a circular linked list)"
Diana Picus via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 18 04:17:53 PDT 2016
Author: rovka
Date: Thu Aug 18 06:17:53 2016
New Revision: 279053
URL: http://llvm.org/viewvc/llvm-project?rev=279053&view=rev
Log:
Revert "ADT: Remove UB in ilist (and use a circular linked list)"
This reverts commit r278974 which broke some of our bots (e.g.
clang-cmake-aarch64-42vma, clang-cmake-aarch64-full).
Modified:
llvm/trunk/include/llvm/ADT/ilist.h
llvm/trunk/include/llvm/ADT/ilist_node.h
llvm/trunk/unittests/ADT/ilistTest.cpp
Modified: llvm/trunk/include/llvm/ADT/ilist.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/ilist.h?rev=279053&r1=279052&r2=279053&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/ilist.h (original)
+++ llvm/trunk/include/llvm/ADT/ilist.h Thu Aug 18 06:17:53 2016
@@ -15,16 +15,17 @@
// replacement does not provide a constant time size() method, so be careful to
// use empty() when you really want to know if it's empty.
//
-// The ilist class is implemented as a circular list. The list itself contains
-// a sentinel node, whose Next points at begin() and whose Prev points at
-// rbegin(). The sentinel node itself serves as end() and rend().
+// The ilist class is implemented by allocating a 'tail' node when the list is
+// created (using ilist_traits<>::createSentinel()). This tail node is
+// absolutely required because the user must be able to compute end()-1. Because
+// of this, users of the direct next/prev links will see an extra link on the
+// end of the list, which should be ignored.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_ILIST_H
#define LLVM_ADT_ILIST_H
-#include "llvm/ADT/ilist_node.h"
#include "llvm/Support/Compiler.h"
#include <algorithm>
#include <cassert>
@@ -37,42 +38,37 @@ namespace llvm {
template<typename NodeTy, typename Traits> class iplist;
template<typename NodeTy> class ilist_iterator;
-/// An access class for ilist_node private API.
+/// An access class for next/prev on ilist_nodes.
///
/// This gives access to the private parts of ilist nodes. Nodes for an ilist
/// should friend this class if they inherit privately from ilist_node.
///
-/// It's strongly discouraged to *use* this class outside of the ilist
+/// It's strongly discouraged to *use* this class outside of ilist
/// implementation.
struct ilist_node_access {
- template <typename T> static ilist_node<T> *getNodePtr(T *N) { return N; }
- template <typename T> static const ilist_node<T> *getNodePtr(const T *N) {
- return N;
- }
-
- template <typename T> static ilist_node<T> *getPrev(ilist_node<T> *N) {
+ template <typename NodeTy> static NodeTy *getPrev(NodeTy *N) {
return N->getPrev();
}
- template <typename T> static ilist_node<T> *getNext(ilist_node<T> *N) {
+ template <typename NodeTy> static NodeTy *getNext(NodeTy *N) {
return N->getNext();
}
- template <typename T> static const ilist_node<T> *getPrev(const ilist_node<T> *N) {
+ template <typename NodeTy> static const NodeTy *getPrev(const NodeTy *N) {
return N->getPrev();
}
- template <typename T> static const ilist_node<T> *getNext(const ilist_node<T> *N) {
+ template <typename NodeTy> static const NodeTy *getNext(const NodeTy *N) {
return N->getNext();
}
- template <typename T> static void setPrev(ilist_node<T> *N, ilist_node<T> *Prev) {
+ template <typename NodeTy> static void setPrev(NodeTy *N, NodeTy *Prev) {
N->setPrev(Prev);
}
- template <typename T> static void setNext(ilist_node<T> *N, ilist_node<T> *Next) {
+ template <typename NodeTy> static void setNext(NodeTy *N, NodeTy *Next) {
N->setNext(Next);
}
- template <typename T> static void setPrev(ilist_node<T> *N, std::nullptr_t) {
+ template <typename NodeTy> static void setPrev(NodeTy *N, std::nullptr_t) {
N->setPrev(nullptr);
}
- template <typename T> static void setNext(ilist_node<T> *N, std::nullptr_t) {
+ template <typename NodeTy> static void setNext(NodeTy *N, std::nullptr_t) {
N->setNext(nullptr);
}
};
@@ -97,31 +93,111 @@ template <class TraitsT, class NodeT> st
static const bool value = sizeof(hasGetNext<TraitsT>(nullptr)) == sizeof(Yes);
};
-/// Type trait to check for a traits class that has a createSentinel member (as
-/// a canary for any of the ilist_sentinel_traits API).
-template <class TraitsT> struct HasCreateSentinel {
- typedef char Yes[1];
- typedef char No[2];
- template <size_t N> struct SFINAE {};
+} // end namespace ilist_detail
- template <class U>
- static Yes &
- hasCreateSentinel(SFINAE<sizeof(make<U>().createSentinel())> * = 0);
- template <class U> static No &hasCreateSentinel(...);
+template<typename NodeTy>
+struct ilist_traits;
- static const bool value =
- sizeof(hasCreateSentinel<TraitsT>(nullptr)) == sizeof(Yes);
+/// ilist_sentinel_traits - A fragment for template traits for intrusive list
+/// that provides default sentinel implementations for common operations.
+///
+/// ilist_sentinel_traits implements a lazy dynamic sentinel allocation
+/// strategy. The sentinel is stored in the prev field of ilist's Head.
+///
+template<typename NodeTy>
+struct ilist_sentinel_traits {
+ /// createSentinel - create the dynamic sentinel
+ static NodeTy *createSentinel() { return new NodeTy(); }
+
+ /// destroySentinel - deallocate the dynamic sentinel
+ static void destroySentinel(NodeTy *N) { delete N; }
+
+ /// provideInitialHead - when constructing an ilist, provide a starting
+ /// value for its Head
+ /// @return null node to indicate that it needs to be allocated later
+ static NodeTy *provideInitialHead() { return nullptr; }
+
+ /// ensureHead - make sure that Head is either already
+ /// initialized or assigned a fresh sentinel
+ /// @return the sentinel
+ static NodeTy *ensureHead(NodeTy *&Head) {
+ if (!Head) {
+ Head = ilist_traits<NodeTy>::createSentinel();
+ ilist_traits<NodeTy>::noteHead(Head, Head);
+ ilist_node_access::setNext(Head, nullptr);
+ return Head;
+ }
+ return ilist_node_access::getPrev(Head);
+ }
+
+ /// noteHead - stash the sentinel into its default location
+ static void noteHead(NodeTy *NewHead, NodeTy *Sentinel) {
+ ilist_node_access::setPrev(NewHead, Sentinel);
+ }
};
-} // end namespace ilist_detail
+template <typename NodeTy> class ilist_half_node;
+template <typename NodeTy> class ilist_node;
+
+/// Traits with an embedded ilist_node as a sentinel.
+template <typename NodeTy> struct ilist_embedded_sentinel_traits {
+ /// Get hold of the node that marks the end of the list.
+ ///
+ /// FIXME: This downcast is UB. See llvm.org/PR26753.
+ LLVM_NO_SANITIZE("object-size")
+ NodeTy *createSentinel() const {
+ // Since i(p)lists always publicly derive from their corresponding traits,
+ // placing a data member in this class will augment the i(p)list. But since
+ // the NodeTy is expected to be publicly derive from ilist_node<NodeTy>,
+ // there is a legal viable downcast from it to NodeTy. We use this trick to
+ // superimpose an i(p)list with a "ghostly" NodeTy, which becomes the
+ // sentinel. Dereferencing the sentinel is forbidden (save the
+ // ilist_node<NodeTy>), so no one will ever notice the superposition.
+ return static_cast<NodeTy *>(&Sentinel);
+ }
+ static void destroySentinel(NodeTy *) {}
+
+ NodeTy *provideInitialHead() const { return createSentinel(); }
+ NodeTy *ensureHead(NodeTy *) const { return createSentinel(); }
+ static void noteHead(NodeTy *, NodeTy *) {}
-template <typename NodeTy> struct ilist_traits;
+private:
+ mutable ilist_node<NodeTy> Sentinel;
+};
-// TODO: Delete uses from subprojects, then delete these.
-template <typename NodeTy> struct ilist_sentinel_traits {};
-template <typename NodeTy> struct ilist_embedded_sentinel_traits {};
-template <typename NodeTy> struct ilist_half_embedded_sentinel_traits {};
-template <typename NodeTy> struct ilist_full_embedded_sentinel_traits {};
+/// Trait with an embedded ilist_half_node as a sentinel.
+template <typename NodeTy> struct ilist_half_embedded_sentinel_traits {
+ /// Get hold of the node that marks the end of the list.
+ ///
+ /// FIXME: This downcast is UB. See llvm.org/PR26753.
+ LLVM_NO_SANITIZE("object-size")
+ NodeTy *createSentinel() const {
+ // See comment in ilist_embedded_sentinel_traits::createSentinel().
+ return static_cast<NodeTy *>(&Sentinel);
+ }
+ static void destroySentinel(NodeTy *) {}
+
+ NodeTy *provideInitialHead() const { return createSentinel(); }
+ NodeTy *ensureHead(NodeTy *) const { return createSentinel(); }
+ static void noteHead(NodeTy *, NodeTy *) {}
+
+private:
+ mutable ilist_half_node<NodeTy> Sentinel;
+};
+
+/// Traits with an embedded full node as a sentinel.
+template <typename NodeTy> struct ilist_full_embedded_sentinel_traits {
+ /// Get hold of the node that marks the end of the list.
+ NodeTy *createSentinel() const { return &Sentinel; }
+ static void destroySentinel(NodeTy *) {}
+
+ NodeTy *provideInitialHead() const { return createSentinel(); }
+ NodeTy *ensureHead(NodeTy *) const { return createSentinel(); }
+ static void noteHead(NodeTy *, NodeTy *) {}
+
+private:
+ mutable NodeTy Sentinel;
+};
/// ilist_node_traits - A fragment for template traits for intrusive list
/// that provides default node related operations.
@@ -143,7 +219,8 @@ struct ilist_node_traits {
/// for all common operations.
///
template <typename NodeTy>
-struct ilist_default_traits : public ilist_node_traits<NodeTy> {};
+struct ilist_default_traits : public ilist_sentinel_traits<NodeTy>,
+ public ilist_node_traits<NodeTy> {};
// Template traits for intrusive list. By specializing this template class, you
// can change what next/prev fields are used to store the links...
@@ -186,15 +263,16 @@ public:
typedef node_type &node_reference;
private:
- node_pointer NodePtr = nullptr;
+ pointer NodePtr;
public:
/// Create from an ilist_node.
- explicit ilist_iterator(node_reference N) : NodePtr(&N) {}
+ explicit ilist_iterator(node_reference N)
+ : NodePtr(static_cast<NodeTy *>(&N)) {}
explicit ilist_iterator(pointer NP) : NodePtr(NP) {}
explicit ilist_iterator(reference NR) : NodePtr(&NR) {}
- ilist_iterator() = default;
+ ilist_iterator() : NodePtr(nullptr) {}
// This is templated so that we can allow constructing a const iterator from
// a nonconst iterator...
@@ -203,23 +281,20 @@ public:
const ilist_iterator<node_ty> &RHS,
typename std::enable_if<std::is_convertible<node_ty *, NodeTy *>::value,
void *>::type = nullptr)
- : NodePtr(RHS.getNodePtr()) {}
+ : NodePtr(RHS.getNodePtrUnchecked()) {}
// This is templated so that we can allow assigning to a const iterator from
// a nonconst iterator...
template <class node_ty>
const ilist_iterator &operator=(const ilist_iterator<node_ty> &RHS) {
- NodePtr = RHS.getNodePtr();
+ NodePtr = RHS.getNodePtrUnchecked();
return *this;
}
void reset(pointer NP) { NodePtr = NP; }
// Accessors...
- reference operator*() const {
- assert(!NodePtr->isKnownSentinel());
- return static_cast<NodeTy &>(*getNodePtr());
- }
+ reference operator*() const { return *NodePtr; }
pointer operator->() const { return &operator*(); }
// Comparison operators
@@ -253,6 +328,9 @@ public:
/// Get the underlying ilist_node.
node_pointer getNodePtr() const { return static_cast<node_pointer>(NodePtr); }
+
+ // Internal interface, do not use...
+ pointer getNodePtrUnchecked() const { return NodePtr; }
};
// Allow ilist_iterators to convert into pointers to a node automatically when
@@ -278,33 +356,56 @@ template<typename NodeTy> struct simplif
//===----------------------------------------------------------------------===//
//
-/// The subset of list functionality that can safely be used on nodes of
-/// polymorphic types, i.e. a heterogeneous list with a common base class that
-/// holds the next/prev pointers. The only state of the list itself is an
-/// ilist_sentinel, which holds pointers to the first and last nodes in the
-/// list.
+/// iplist - The subset of list functionality that can safely be used on nodes
+/// of polymorphic types, i.e. a heterogeneous list with a common base class that
+/// holds the next/prev pointers. The only state of the list itself is a single
+/// pointer to the head of the list.
+///
+/// This list can be in one of three interesting states:
+/// 1. The list may be completely unconstructed. In this case, the head
+/// pointer is null. When in this form, any query for an iterator (e.g.
+/// begin() or end()) causes the list to transparently change to state #2.
+/// 2. The list may be empty, but contain a sentinel for the end iterator. This
+/// sentinel is created by the Traits::createSentinel method and is a link
+/// in the list. When the list is empty, the pointer in the iplist points
+/// to the sentinel. Once the sentinel is constructed, it
+/// is not destroyed until the list is.
+/// 3. The list may contain actual objects in it, which are stored as a doubly
+/// linked list of nodes. One invariant of the list is that the predecessor
+/// of the first node in the list always points to the last node in the list,
+/// and the successor pointer for the sentinel (which always stays at the
+/// end of the list) is always null.
+///
template <typename NodeTy, typename Traits = ilist_traits<NodeTy>>
class iplist : public Traits, ilist_node_access {
- // TODO: Drop these assertions anytime after 4.0 is branched (keep them for
- // one release to help out-of-tree code update).
#if !defined(_MSC_VER)
// FIXME: This fails in MSVC, but it's worth keeping around to help
// non-Windows users root out bugs in their ilist_traits.
static_assert(!ilist_detail::HasGetNext<Traits, NodeTy>::value,
"ilist next and prev links are not customizable!");
- static_assert(!ilist_detail::HasCreateSentinel<Traits>::value,
- "ilist sentinel is not customizable!");
#endif
- ilist_sentinel<NodeTy> Sentinel;
+ mutable NodeTy *Head;
- typedef ilist_node<NodeTy> node_type;
- typedef const ilist_node<NodeTy> const_node_type;
+ // Use the prev node pointer of 'head' as the tail pointer. This is really a
+ // circularly linked list where we snip the 'next' link from the sentinel node
+ // back to the first node in the list (to preserve assertions about going off
+ // the end of the list).
+ NodeTy *getTail() { return this->ensureHead(Head); }
+ const NodeTy *getTail() const { return this->ensureHead(Head); }
+ void setTail(NodeTy *N) const { this->noteHead(Head, N); }
+
+ /// CreateLazySentinel - This method verifies whether the sentinel for the
+ /// list has been created and lazily makes it if not.
+ void CreateLazySentinel() const {
+ this->ensureHead(Head);
+ }
static bool op_less(NodeTy &L, NodeTy &R) { return L < R; }
static bool op_equal(NodeTy &L, NodeTy &R) { return L == R; }
- // Copying intrusively linked nodes doesn't make sense.
+ // No fundamental reason why iplist can't be copyable, but the default
+ // copy/copy-assign won't do.
iplist(const iplist &) = delete;
void operator=(const iplist &) = delete;
@@ -321,14 +422,30 @@ public:
typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
typedef std::reverse_iterator<iterator> reverse_iterator;
- iplist() = default;
- ~iplist() { clear(); }
+ iplist() : Head(this->provideInitialHead()) {}
+ ~iplist() {
+ if (!Head) return;
+ clear();
+ Traits::destroySentinel(getTail());
+ }
// Iterator creation methods.
- iterator begin() { return ++iterator(Sentinel); }
- const_iterator begin() const { return ++const_iterator(Sentinel); }
- iterator end() { return iterator(Sentinel); }
- const_iterator end() const { return const_iterator(Sentinel); }
+ iterator begin() {
+ CreateLazySentinel();
+ return iterator(Head);
+ }
+ const_iterator begin() const {
+ CreateLazySentinel();
+ return const_iterator(Head);
+ }
+ iterator end() {
+ CreateLazySentinel();
+ return iterator(getTail());
+ }
+ const_iterator end() const {
+ CreateLazySentinel();
+ return const_iterator(getTail());
+ }
// reverse iterator creation methods.
reverse_iterator rbegin() { return reverse_iterator(end()); }
@@ -339,39 +456,44 @@ public:
// Miscellaneous inspection routines.
size_type max_size() const { return size_type(-1); }
- bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const { return Sentinel.empty(); }
+ bool LLVM_ATTRIBUTE_UNUSED_RESULT empty() const {
+ return !Head || Head == getTail();
+ }
// Front and back accessor functions...
reference front() {
assert(!empty() && "Called front() on empty list!");
- return *begin();
+ return *Head;
}
const_reference front() const {
assert(!empty() && "Called front() on empty list!");
- return *begin();
+ return *Head;
}
reference back() {
assert(!empty() && "Called back() on empty list!");
- return *--end();
+ return *this->getPrev(getTail());
}
const_reference back() const {
assert(!empty() && "Called back() on empty list!");
- return *--end();
+ return *this->getPrev(getTail());
}
void swap(iplist &RHS) {
assert(0 && "Swap does not use list traits callback correctly yet!");
- std::swap(Sentinel, RHS.Sentinel);
+ std::swap(Head, RHS.Head);
}
iterator insert(iterator where, NodeTy *New) {
- node_type *NewN = this->getNodePtr(New);
- node_type *Next = where.getNodePtr();
- node_type *Prev = this->getPrev(Next);
- this->setNext(NewN, Next);
- this->setPrev(NewN, Prev);
- this->setNext(Prev, NewN);
- this->setPrev(Next, NewN);
+ NodeTy *CurNode = where.getNodePtrUnchecked();
+ NodeTy *PrevNode = this->getPrev(CurNode);
+ this->setNext(New, CurNode);
+ this->setPrev(New, PrevNode);
+
+ if (CurNode != Head) // Is PrevNode off the beginning of the list?
+ this->setNext(PrevNode, New);
+ else
+ Head = New;
+ this->setPrev(CurNode, New);
this->addNodeToList(New); // Notify traits that we added a node...
return iterator(New);
@@ -391,23 +513,24 @@ public:
NodeTy *remove(iterator &IT) {
assert(IT != end() && "Cannot remove end of list!");
NodeTy *Node = &*IT;
- node_type *Base = this->getNodePtr(Node);
- node_type *Next = this->getNext(Base);
- node_type *Prev = this->getPrev(Base);
-
- this->setNext(Prev, Next);
- this->setPrev(Next, Prev);
- IT = iterator(*Next);
+ NodeTy *NextNode = this->getNext(Node);
+ NodeTy *PrevNode = this->getPrev(Node);
+
+ if (Node != Head) // Is PrevNode off the beginning of the list?
+ this->setNext(PrevNode, NextNode);
+ else
+ Head = NextNode;
+ this->setPrev(NextNode, PrevNode);
+ IT.reset(NextNode);
this->removeNodeFromList(Node); // Notify traits that we removed a node...
// Set the next/prev pointers of the current node to null. This isn't
// strictly required, but this catches errors where a node is removed from
// an ilist (and potentially deleted) with iterators still pointing at it.
- // After those iterators are incremented or decremented, they become
- // default-constructed iterators, and will assert on increment, decrement,
- // and dereference instead of "usually working".
- this->setNext(Base, nullptr);
- this->setPrev(Base, nullptr);
+ // When those iterators are incremented or decremented, they will assert on
+ // the null next/prev pointer instead of "usually working".
+ this->setNext(Node, nullptr);
+ this->setPrev(Node, nullptr);
return Node;
}
@@ -433,7 +556,12 @@ public:
///
/// This should only be used immediately before freeing nodes in bulk to
/// avoid traversing the list and bringing all the nodes into cache.
- void clearAndLeakNodesUnsafely() { Sentinel.reset(); }
+ void clearAndLeakNodesUnsafely() {
+ if (Head) {
+ Head = getTail();
+ this->setPrev(Head, Head);
+ }
+ }
private:
// transfer - The heart of the splice function. Move linked list nodes from
@@ -442,34 +570,48 @@ private:
void transfer(iterator position, iplist &L2, iterator first, iterator last) {
assert(first != last && "Should be checked by callers");
// Position cannot be contained in the range to be transferred.
+ // Check for the most common mistake.
assert(position != first &&
- // Check for the most common mistake.
"Insertion point can't be one of the transferred nodes");
- if (position == last)
- return;
-
- // Get raw hooks to the first and final nodes being transferred.
- node_type *First = first.getNodePtr();
- node_type *Final = (--last).getNodePtr();
-
- // Detach from old list/position.
- node_type *Prev = this->getPrev(First);
- node_type *Next = this->getNext(Final);
- this->setNext(Prev, Next);
- this->setPrev(Next, Prev);
-
- // Splice [First, Final] into its new list/position.
- Next = position.getNodePtr();
- Prev = this->getPrev(Next);
- this->setNext(Final, Next);
- this->setPrev(First, Prev);
- this->setNext(Prev, First);
- this->setPrev(Next, Final);
-
- // Callback. Note that the nodes have moved from before-last to
- // before-position.
- this->transferNodesFromList(L2, first, position);
+ if (position != last) {
+ // Note: we have to be careful about the case when we move the first node
+ // in the list. This node is the list sentinel node and we can't move it.
+ NodeTy *ThisSentinel = getTail();
+ setTail(nullptr);
+ NodeTy *L2Sentinel = L2.getTail();
+ L2.setTail(nullptr);
+
+ // Remove [first, last) from its old position.
+ NodeTy *First = &*first, *Prev = this->getPrev(First);
+ NodeTy *Next = last.getNodePtrUnchecked(), *Last = this->getPrev(Next);
+ if (Prev)
+ this->setNext(Prev, Next);
+ else
+ L2.Head = Next;
+ this->setPrev(Next, Prev);
+
+ // Splice [first, last) into its new position.
+ NodeTy *PosNext = position.getNodePtrUnchecked();
+ NodeTy *PosPrev = this->getPrev(PosNext);
+
+ // Fix head of list...
+ if (PosPrev)
+ this->setNext(PosPrev, First);
+ else
+ Head = First;
+ this->setPrev(First, PosPrev);
+
+ // Fix end of list...
+ this->setNext(Last, PosNext);
+ this->setPrev(PosNext, Last);
+
+ this->transferNodesFromList(L2, iterator(First), iterator(PosNext));
+
+ // Now that everything is set, restore the pointers to the list sentinels.
+ L2.setTail(L2Sentinel);
+ setTail(ThisSentinel);
+ }
}
public:
@@ -479,6 +621,7 @@ public:
//
size_type LLVM_ATTRIBUTE_UNUSED_RESULT size() const {
+ if (!Head) return 0; // Don't require construction of sentinel if empty.
return std::distance(begin(), end());
}
@@ -488,7 +631,7 @@ public:
return last;
}
- void clear() { erase(begin(), end()); }
+ void clear() { if (Head) erase(begin(), end()); }
// Front and back inserters...
void push_front(NodeTy *val) { insert(begin(), val); }
Modified: llvm/trunk/include/llvm/ADT/ilist_node.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/ilist_node.h?rev=279053&r1=279052&r2=279053&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/ilist_node.h (original)
+++ llvm/trunk/include/llvm/ADT/ilist_node.h Thu Aug 18 06:17:53 2016
@@ -15,8 +15,6 @@
#ifndef LLVM_ADT_ILIST_NODE_H
#define LLVM_ADT_ILIST_NODE_H
-#include <llvm/ADT/PointerIntPair.h>
-
namespace llvm {
template<typename NodeTy>
@@ -24,81 +22,46 @@ struct ilist_traits;
template <typename NodeTy> struct ilist_embedded_sentinel_traits;
template <typename NodeTy> struct ilist_half_embedded_sentinel_traits;
-/// Base class for ilist nodes.
-struct ilist_node_base {
-#ifdef LLVM_ENABLE_ABI_BREAKING_CHECKS
- PointerIntPair<ilist_node_base *, 1> PrevAndSentinel;
-
- void setPrev(ilist_node_base *Prev) { PrevAndSentinel.setPointer(Prev); }
- ilist_node_base *getPrev() const { return PrevAndSentinel.getPointer(); }
-
- bool isKnownSentinel() const { return PrevAndSentinel.getInt(); }
- void initializeSentinel() { PrevAndSentinel.setInt(true); }
-#else
- ilist_node_base *Prev = nullptr;
-
- void setPrev(ilist_node_base *Prev) { this->Prev = Prev; }
- ilist_node_base *getPrev() const { return Prev; }
-
- bool isKnownSentinel() const { return false; }
- void initializeSentinel() {}
-#endif
-
- ilist_node_base *Next = nullptr;
+/// ilist_half_node - Base class that provides prev services for sentinels.
+///
+template<typename NodeTy>
+class ilist_half_node {
+ friend struct ilist_traits<NodeTy>;
+ friend struct ilist_half_embedded_sentinel_traits<NodeTy>;
+ NodeTy *Prev;
+protected:
+ NodeTy *getPrev() { return Prev; }
+ const NodeTy *getPrev() const { return Prev; }
+ void setPrev(NodeTy *P) { Prev = P; }
+ ilist_half_node() : Prev(nullptr) {}
};
struct ilist_node_access;
template <typename NodeTy> class ilist_iterator;
-template <typename NodeTy> class ilist_sentinel;
-/// Templated wrapper class.
-template <typename NodeTy> class ilist_node : ilist_node_base {
+/// Base class that provides next/prev services for ilist nodes.
+template<typename NodeTy>
+class ilist_node : private ilist_half_node<NodeTy> {
friend struct ilist_node_access;
friend struct ilist_traits<NodeTy>;
friend struct ilist_half_embedded_sentinel_traits<NodeTy>;
friend struct ilist_embedded_sentinel_traits<NodeTy>;
- friend class ilist_iterator<NodeTy>;
- friend class ilist_sentinel<NodeTy>;
-
+ NodeTy *Next;
+ NodeTy *getNext() { return Next; }
+ const NodeTy *getNext() const { return Next; }
+ void setNext(NodeTy *N) { Next = N; }
protected:
- ilist_node() = default;
-
-private:
- ilist_node *getPrev() {
- return static_cast<ilist_node *>(ilist_node_base::getPrev());
- }
- ilist_node *getNext() { return static_cast<ilist_node *>(Next); }
-
- const ilist_node *getPrev() const {
- return static_cast<ilist_node *>(ilist_node_base::getPrev());
- }
- const ilist_node *getNext() const { return static_cast<ilist_node *>(Next); }
-
- void setPrev(ilist_node *N) { ilist_node_base::setPrev(N); }
- void setNext(ilist_node *N) { Next = N; }
+ ilist_node() : Next(nullptr) {}
public:
- ilist_iterator<NodeTy> getIterator() { return ilist_iterator<NodeTy>(*this); }
- ilist_iterator<const NodeTy> getIterator() const {
- return ilist_iterator<const NodeTy>(*this);
+ ilist_iterator<NodeTy> getIterator() {
+ // FIXME: Stop downcasting to create the iterator (potential UB).
+ return ilist_iterator<NodeTy>(static_cast<NodeTy *>(this));
}
-
- using ilist_node_base::isKnownSentinel;
-};
-
-template <typename NodeTy> class ilist_sentinel : public ilist_node<NodeTy> {
-public:
- ilist_sentinel() {
- ilist_node_base::initializeSentinel();
- reset();
- }
-
- void reset() {
- this->setPrev(this);
- this->setNext(this);
+ ilist_iterator<const NodeTy> getIterator() const {
+ // FIXME: Stop downcasting to create the iterator (potential UB).
+ return ilist_iterator<const NodeTy>(static_cast<const NodeTy *>(this));
}
-
- bool empty() const { return this == this->getPrev(); }
};
/// An ilist node that can access its parent list.
Modified: llvm/trunk/unittests/ADT/ilistTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/ADT/ilistTest.cpp?rev=279053&r1=279052&r2=279053&view=diff
==============================================================================
--- llvm/trunk/unittests/ADT/ilistTest.cpp (original)
+++ llvm/trunk/unittests/ADT/ilistTest.cpp Thu Aug 18 06:17:53 2016
@@ -128,66 +128,4 @@ TEST(ilistTest, UnsafeClear) {
EXPECT_EQ(6, List.back().Value);
}
-struct NodeWithCallback : ilist_node<NodeWithCallback> {
- int Value = 0;
- bool IsInList = false;
-
- NodeWithCallback() = default;
- NodeWithCallback(int Value) : Value(Value) {}
- NodeWithCallback(const NodeWithCallback &) = delete;
-};
-
-} // end namespace
-
-namespace llvm {
-template <>
-struct ilist_traits<NodeWithCallback>
- : public ilist_node_traits<NodeWithCallback> {
- void addNodeToList(NodeWithCallback *N) { N->IsInList = true; }
- void removeNodeFromList(NodeWithCallback *N) { N->IsInList = false; }
-};
-} // end namespace llvm
-
-namespace {
-
-TEST(ilistTest, addNodeToList) {
- ilist<NodeWithCallback> L;
- NodeWithCallback N(7);
- ASSERT_FALSE(N.IsInList);
-
- L.insert(L.begin(), &N);
- ASSERT_EQ(1u, L.size());
- ASSERT_EQ(&N, &*L.begin());
- ASSERT_TRUE(N.IsInList);
-
- L.remove(&N);
- ASSERT_EQ(0u, L.size());
- ASSERT_FALSE(N.IsInList);
}
-
-struct PrivateNode : private ilist_node<PrivateNode> {
- friend struct llvm::ilist_node_access;
-
- int Value = 0;
-
- PrivateNode() = default;
- PrivateNode(int Value) : Value(Value) {}
- PrivateNode(const PrivateNode &) = delete;
-};
-
-TEST(ilistTest, privateNode) {
- // Instantiate various APIs to be sure they're callable when ilist_node is
- // inherited privately.
- ilist<NodeWithCallback> L;
- NodeWithCallback N(7);
- L.insert(L.begin(), &N);
- ++L.begin();
- (void)*L.begin();
- (void)(L.begin() == L.end());
-
- ilist<NodeWithCallback> L2;
- L2.splice(L2.end(), L);
- L2.remove(&N);
-}
-
-} // end namespace
More information about the llvm-commits
mailing list