ADT: Separate some list manipulation API into ilist_base, NFC

Separate algorithms in iplist<T> that don't depend on T into ilist_base,
and unit test them.

While I was adding unit tests for these algorithms anyway, I also added
unit tests for ilist_node_base and ilist_sentinel<T>.

To make the algorithms and unit tests easier to write, I also did the
following minor changes as a drive-by:
- encapsulate Prev/Next in ilist_node_base to so that algorithms are
  easier to read, and
- update ilist_node_access API to take nodes by reference.

There should be no real functionality change here.

llvm-svn: 279484

include/llvm/ADT/ilist.h

@@ -50,30 +50,19 @@ struct ilist_node_access {
     return N;
   }
 
-  template <typename T> static ilist_node<T> *getPrev(ilist_node<T> *N) {
-    return N->getPrev();
+  template <typename T> static ilist_node<T> *getPrev(ilist_node<T> &N) {
+    return N.getPrev();
   }
-  template <typename T> static ilist_node<T> *getNext(ilist_node<T> *N) {
-    return N->getNext();
+  template <typename T> static ilist_node<T> *getNext(ilist_node<T> &N) {
+    return N.getNext();
   }
-  template <typename T> static const ilist_node<T> *getPrev(const ilist_node<T> *N) {
-    return N->getPrev();
+  template <typename T>
+  static const ilist_node<T> *getPrev(const ilist_node<T> &N) {
+    return N.getPrev();
   }
-  template <typename T> static const ilist_node<T> *getNext(const ilist_node<T> *N) {
-    return N->getNext();
-  }
-
-  template <typename T> static void setPrev(ilist_node<T> *N, ilist_node<T> *Prev) {
-    N->setPrev(Prev);
-  }
-  template <typename T> static void setNext(ilist_node<T> *N, ilist_node<T> *Next) {
-    N->setNext(Next);
-  }
-  template <typename T> static void setPrev(ilist_node<T> *N, std::nullptr_t) {
-    N->setPrev(nullptr);
-  }
-  template <typename T> static void setNext(ilist_node<T> *N, std::nullptr_t) {
-    N->setNext(nullptr);
+  template <typename T>
+  static const ilist_node<T> *getNext(const ilist_node<T> &N) {
+    return N.getNext();
   }
 };
 
@@ -228,12 +217,12 @@ public:
 
   // Increment and decrement operators...
   ilist_iterator &operator--() {
-    NodePtr = ilist_node_access::getPrev(NodePtr);
+    NodePtr = ilist_node_access::getPrev(*NodePtr);
     assert(NodePtr && "--'d off the beginning of an ilist!");
     return *this;
   }
   ilist_iterator &operator++() {
-    NodePtr = ilist_node_access::getNext(NodePtr);
+    NodePtr = ilist_node_access::getNext(*NodePtr);
     return *this;
   }
   ilist_iterator operator--(int) {
@@ -271,6 +260,64 @@ template<typename NodeTy> struct simplify_type<const ilist_iterator<NodeTy> > {
   }
 };
 
+/// Implementations of list algorithms using ilist_node_base.
+class ilist_base {
+public:
+  static void insertBeforeImpl(ilist_node_base &Next, ilist_node_base &N) {
+    ilist_node_base &Prev = *Next.getPrev();
+    N.setNext(&Next);
+    N.setPrev(&Prev);
+    Prev.setNext(&N);
+    Next.setPrev(&N);
+  }
+
+  static void removeImpl(ilist_node_base &N) {
+    ilist_node_base *Prev = N.getPrev();
+    ilist_node_base *Next = N.getNext();
+    Next->setPrev(Prev);
+    Prev->setNext(Next);
+
+    // Not strictly necessary, but helps catch a class of bugs.
+    N.setPrev(nullptr);
+    N.setNext(nullptr);
+  }
+
+  static void transferBeforeImpl(ilist_node_base &Next, ilist_node_base &First,
+                                 ilist_node_base &Last) {
+    assert(&Next != &Last && "Should be checked by callers");
+    assert(&First != &Last && "Should be checked by callers");
+    // Position cannot be contained in the range to be transferred.
+    assert(&Next != &First &&
+           // Check for the most common mistake.
+           "Insertion point can't be one of the transferred nodes");
+
+    ilist_node_base &Final = *Last.getPrev();
+
+    // Detach from old list/position.
+    First.getPrev()->setNext(&Last);
+    Last.setPrev(First.getPrev());
+
+    // Splice [First, Final] into its new list/position.
+    ilist_node_base &Prev = *Next.getPrev();
+    Final.setNext(&Next);
+    First.setPrev(&Prev);
+    Prev.setNext(&First);
+    Next.setPrev(&Final);
+  }
+
+  template <class T>
+  static void insertBefore(ilist_node<T> &Next, ilist_node<T> &N) {
+    insertBeforeImpl(Next, N);
+  }
+
+  template <class T> static void remove(ilist_node<T> &N) { removeImpl(N); }
+
+  template <class T>
+  static void transferBefore(ilist_node<T> &Next, ilist_node<T> &First,
+                             ilist_node<T> &Last) {
+    transferBeforeImpl(Next, First, Last);
+  }
+};
 
 //===----------------------------------------------------------------------===//
 //
@@ -280,7 +327,7 @@ template<typename NodeTy> struct simplify_type<const ilist_iterator<NodeTy> > {
 /// ilist_sentinel, which holds pointers to the first and last nodes in the
 /// list.
 template <typename NodeTy, typename Traits = ilist_traits<NodeTy>>
-class iplist : public Traits, ilist_node_access {
+class iplist : public Traits, ilist_base, ilist_node_access {
   // TODO: Drop this assertion and the transitive type traits anytime after
   // v4.0 is branched (i.e,. keep them for one release to help out-of-tree code
   // update).
@@ -356,13 +403,7 @@ public:
   }
 
   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);
+    ilist_base::insertBefore(*where.getNodePtr(), *this->getNodePtr(New));
 
     this->addNodeToList(New);  // Notify traits that we added a node...
     return iterator(New);
@@ -381,24 +422,9 @@ 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 *Node = &*IT++;
+    ilist_base::remove(*this->getNodePtr(Node));
     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);
     return Node;
   }
 
@@ -431,32 +457,11 @@ private:
   // [first, last) into position.
   //
   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.
-    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);
+    ilist_base::transferBefore(*position.getNodePtr(), *first.getNodePtr(),
+                               *last.getNodePtr());
 
     // Callback.  Note that the nodes have moved from before-last to
     // before-position.

include/llvm/ADT/ilist_node.h

@@ -23,18 +23,22 @@ template<typename NodeTy>
 struct ilist_traits;
 
 /// Base class for ilist nodes.
-struct ilist_node_base {
+class ilist_node_base {
 #ifdef LLVM_ENABLE_ABI_BREAKING_CHECKS
   PointerIntPair<ilist_node_base *, 1> PrevAndSentinel;
+#else
+  ilist_node_base *Prev = nullptr;
+#endif
+  ilist_node_base *Next = nullptr;
 
+public:
+#ifdef LLVM_ENABLE_ABI_BREAKING_CHECKS
   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; }
 
@@ -42,7 +46,8 @@ struct ilist_node_base {
   void initializeSentinel() {}
 #endif
 
-  ilist_node_base *Next = nullptr;
+  void setNext(ilist_node_base *Next) { this->Next = Next; }
+  ilist_node_base *getNext() const { return Next; }
 };
 
 struct ilist_node_access;
@@ -51,6 +56,7 @@ template <typename NodeTy> class ilist_sentinel;
 
 /// Templated wrapper class.
 template <typename NodeTy> class ilist_node : ilist_node_base {
+  friend class ilist_base;
   friend struct ilist_node_access;
   friend struct ilist_traits<NodeTy>;
   friend class ilist_iterator<NodeTy>;
@@ -63,15 +69,19 @@ private:
   ilist_node *getPrev() {
     return static_cast<ilist_node *>(ilist_node_base::getPrev());
   }
-  ilist_node *getNext() { return static_cast<ilist_node *>(Next); }
+  ilist_node *getNext() {
+    return static_cast<ilist_node *>(ilist_node_base::getNext());
+  }
 
   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); }
+  const ilist_node *getNext() const {
+    return static_cast<ilist_node *>(ilist_node_base::getNext());
+  }
 
   void setPrev(ilist_node *N) { ilist_node_base::setPrev(N); }
-  void setNext(ilist_node *N) { Next = N; }
+  void setNext(ilist_node *N) { ilist_node_base::setNext(N); }
 
 public:
   ilist_iterator<NodeTy> getIterator() { return ilist_iterator<NodeTy>(*this); }

unittests/ADT/CMakeLists.txt

@@ -18,6 +18,9 @@ set(ADTSources
   FunctionRefTest.cpp
   HashingTest.cpp
   ilistTest.cpp
+  IListBaseTest.cpp
+  IListNodeBaseTest.cpp
+  IListSentinelTest.cpp
   ImmutableMapTest.cpp
   ImmutableSetTest.cpp
   IntEqClassesTest.cpp

unittests/ADT/IListBaseTest.cpp

@@ -0,0 +1,102 @@
+//===- unittests/ADT/IListBaseTest.cpp - ilist_base unit tests ------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/ilist.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+TEST(IListBaseTest, insertBeforeImpl) {
+  ilist_node_base S, A, B;
+  // [S] <-> [S]
+  S.setPrev(&S);
+  S.setNext(&S);
+
+  // [S] <-> A <-> [S]
+  ilist_base::insertBeforeImpl(S, A);
+  EXPECT_EQ(&A, S.getPrev());
+  EXPECT_EQ(&S, A.getPrev());
+  EXPECT_EQ(&A, S.getNext());
+  EXPECT_EQ(&S, A.getNext());
+
+  // [S] <-> A <-> B <-> [S]
+  ilist_base::insertBeforeImpl(S, B);
+  EXPECT_EQ(&B, S.getPrev());
+  EXPECT_EQ(&A, B.getPrev());
+  EXPECT_EQ(&S, A.getPrev());
+  EXPECT_EQ(&A, S.getNext());
+  EXPECT_EQ(&B, A.getNext());
+  EXPECT_EQ(&S, B.getNext());
+}
+
+TEST(IListBaseTest, removeImpl) {
+  ilist_node_base S, A, B;
+
+  // [S] <-> A <-> B <-> [S]
+  S.setPrev(&S);
+  S.setNext(&S);
+  ilist_base::insertBeforeImpl(S, A);
+  ilist_base::insertBeforeImpl(S, B);
+
+  // [S] <-> B <-> [S]
+  ilist_base::removeImpl(A);
+  EXPECT_EQ(&B, S.getPrev());
+  EXPECT_EQ(&S, B.getPrev());
+  EXPECT_EQ(&B, S.getNext());
+  EXPECT_EQ(&S, B.getNext());
+  EXPECT_EQ(nullptr, A.getPrev());
+  EXPECT_EQ(nullptr, A.getNext());
+
+  // [S] <-> [S]
+  ilist_base::removeImpl(B);
+  EXPECT_EQ(&S, S.getPrev());
+  EXPECT_EQ(&S, S.getNext());
+  EXPECT_EQ(nullptr, B.getPrev());
+  EXPECT_EQ(nullptr, B.getNext());
+}
+
+TEST(IListBaseTest, transferBeforeImpl) {
+  ilist_node_base S1, S2, A, B, C, D, E;
+
+  // [S1] <-> A <-> B <-> C <-> [S1]
+  S1.setPrev(&S1);
+  S1.setNext(&S1);
+  ilist_base::insertBeforeImpl(S1, A);
+  ilist_base::insertBeforeImpl(S1, B);
+  ilist_base::insertBeforeImpl(S1, C);
+
+  // [S2] <-> D <-> E <-> [S2]
+  S2.setPrev(&S2);
+  S2.setNext(&S2);
+  ilist_base::insertBeforeImpl(S2, D);
+  ilist_base::insertBeforeImpl(S2, E);
+
+  // [S1] <-> C <-> [S1]
+  ilist_base::transferBeforeImpl(D, A, C);
+  EXPECT_EQ(&C, S1.getPrev());
+  EXPECT_EQ(&S1, C.getPrev());
+  EXPECT_EQ(&C, S1.getNext());
+  EXPECT_EQ(&S1, C.getNext());
+
+  // [S2] <-> A <-> B <-> D <-> E <-> [S2]
+  EXPECT_EQ(&E, S2.getPrev());
+  EXPECT_EQ(&D, E.getPrev());
+  EXPECT_EQ(&B, D.getPrev());
+  EXPECT_EQ(&A, B.getPrev());
+  EXPECT_EQ(&S2, A.getPrev());
+  EXPECT_EQ(&A, S2.getNext());
+  EXPECT_EQ(&B, A.getNext());
+  EXPECT_EQ(&D, B.getNext());
+  EXPECT_EQ(&E, D.getNext());
+  EXPECT_EQ(&S2, E.getNext());
+}
+
+} // end namespace

unittests/ADT/IListNodeBaseTest.cpp

@@ -0,0 +1,60 @@
+//===- unittests/ADT/IListNodeBaseTest.cpp - ilist_node_base unit tests ---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/ilist_node.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+TEST(IListNodeBaseTest, DefaultConstructor) {
+  ilist_node_base A;
+  EXPECT_EQ(nullptr, A.getPrev());
+  EXPECT_EQ(nullptr, A.getNext());
+  EXPECT_FALSE(A.isKnownSentinel());
+}
+
+TEST(IListNodeBaseTest, setPrevAndNext) {
+  ilist_node_base A, B, C;
+  A.setPrev(&B);
+  EXPECT_EQ(&B, A.getPrev());
+  EXPECT_EQ(nullptr, A.getNext());
+  EXPECT_EQ(nullptr, B.getPrev());
+  EXPECT_EQ(nullptr, B.getNext());
+  EXPECT_EQ(nullptr, C.getPrev());
+  EXPECT_EQ(nullptr, C.getNext());
+
+  A.setNext(&C);
+  EXPECT_EQ(&B, A.getPrev());
+  EXPECT_EQ(&C, A.getNext());
+  EXPECT_EQ(nullptr, B.getPrev());
+  EXPECT_EQ(nullptr, B.getNext());
+  EXPECT_EQ(nullptr, C.getPrev());
+  EXPECT_EQ(nullptr, C.getNext());
+}
+
+TEST(IListNodeBaseTest, isKnownSentinel) {
+  ilist_node_base A, B;
+  EXPECT_FALSE(A.isKnownSentinel());
+  A.setPrev(&B);
+  A.setNext(&B);
+  EXPECT_EQ(&B, A.getPrev());
+  EXPECT_EQ(&B, A.getNext());
+  A.initializeSentinel();
+#ifdef LLVM_ENABLE_ABI_BREAKING_CHECKS
+  EXPECT_TRUE(A.isKnownSentinel());
+#else
+  EXPECT_FALSE(A.isKnownSentinel());
+#endif
+  EXPECT_EQ(&B, A.getPrev());
+  EXPECT_EQ(&B, A.getNext());
+}
+
+} // end namespace

unittests/ADT/IListSentinelTest.cpp

@@ -0,0 +1,37 @@
+//===- unittests/ADT/IListSentinelTest.cpp - ilist_sentinel unit tests ----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/ilist.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+class Node : public ilist_node<Node> {};
+
+TEST(IListSentinelTest, DefaultConstructor) {
+  ilist_sentinel<Node> S;
+  EXPECT_EQ(&S, ilist_node_access::getPrev(S));
+  EXPECT_EQ(&S, ilist_node_access::getNext(S));
+#ifdef LLVM_ENABLE_ABI_BREAKING_CHECKS
+  EXPECT_TRUE(S.isKnownSentinel());
+#else
+  EXPECT_FALSE(S.isKnownSentinel());
+#endif
+}
+
+TEST(IListSentinelTest, NormalNodeIsNotKnownSentinel) {
+  Node N;
+  EXPECT_EQ(nullptr, ilist_node_access::getPrev(N));
+  EXPECT_EQ(nullptr, ilist_node_access::getNext(N));
+  EXPECT_FALSE(N.isKnownSentinel());
+}
+
+} // end namespace