Add some basic Pool-allocation infrastructure. This adds a Recycler class,

for handling bookkeeping for deleted objects, as well as the alist class
template, for keeping lists of objects allocated from Recyclers, and some
related utilities.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53210 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/alist.h

@@ -0,0 +1,292 @@
+//==- llvm/ADT/alist.h - Linked lists with hooks -----------------*- 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 alist class template, and related infrastructure.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_ALIST_H
+#define LLVM_ADT_ALIST_H
+
+#include <cassert>
+#include "llvm/ADT/alist_node.h"
+#include "llvm/ADT/STLExtras.h"
+
+namespace llvm {
+
+/// alist_iterator - An iterator class for alist.
+///
+template<class T, class LargestT = T, class ValueT = T,
+         class NodeIterT = ilist_iterator<alist_node<T, LargestT> > >
+class alist_iterator : public bidirectional_iterator<ValueT, ptrdiff_t> {
+  typedef bidirectional_iterator<ValueT, ptrdiff_t> super;
+  typedef alist_node<T, LargestT> NodeTy;
+
+  /// NodeIter - The underlying iplist iterator that is being wrapped.
+  NodeIterT NodeIter;
+
+public:
+  typedef size_t size_type;
+  typedef typename super::pointer pointer;
+  typedef typename super::reference reference;
+
+  alist_iterator(NodeIterT NI) : NodeIter(NI) {}
+  alist_iterator(pointer EP) : NodeIter(NodeTy::getNode(EP)) {}
+  alist_iterator() : NodeIter() {}
+
+  // This is templated so that we can allow constructing a const iterator from
+  // a nonconst iterator...
+  template<class V, class W, class X, class Y>
+  alist_iterator(const alist_iterator<V, W, X, Y> &RHS)
+    : NodeIter(RHS.getNodeIterUnchecked()) {}
+
+  // This is templated so that we can allow assigning to a const iterator from
+  // a nonconst iterator...
+  template<class V, class W, class X, class Y>
+  const alist_iterator &operator=(const alist_iterator<V, W, X, Y> &RHS) {
+    NodeIter = RHS.getNodeIterUnchecked();
+    return *this;
+  }
+
+  operator pointer() const { return NodeIter->getElement((T*)0); }
+
+  reference operator*() const { return *NodeIter->getElement((T*)0); }
+  pointer   operator->() const { return &operator*(); }
+
+  bool operator==(const alist_iterator &RHS) const {
+    return NodeIter == RHS.NodeIter;
+  }
+  bool operator!=(const alist_iterator &RHS) const {
+    return NodeIter != RHS.NodeIter;
+  }
+
+  alist_iterator &operator--() {
+    --NodeIter;
+    return *this;
+  }
+  alist_iterator &operator++() {
+    ++NodeIter;
+    return *this;
+  }
+  alist_iterator operator--(int) {
+    alist_iterator tmp = *this;
+    --*this;
+    return tmp;
+  }
+  alist_iterator operator++(int) {
+    alist_iterator tmp = *this;
+    ++*this;
+    return tmp;
+  }
+
+  NodeIterT getNodeIterUnchecked() const { return NodeIter; }
+};
+
+// do not implement. this is to catch errors when people try to use
+// them as random access iterators
+template<class T, class LargestT, class ValueT, class NodeIterT>
+void operator-(int, alist_iterator<T, LargestT, ValueT, NodeIterT>);
+template<class T, class LargestT, class ValueT, class NodeIterT>
+void operator-(alist_iterator<T, LargestT, ValueT, NodeIterT>,int);
+
+template<class T, class LargestT, class ValueT, class NodeIterT>
+void operator+(int, alist_iterator<T, LargestT, ValueT, NodeIterT>);
+template<class T, class LargestT, class ValueT, class NodeIterT>
+void operator+(alist_iterator<T, LargestT, ValueT, NodeIterT>,int);
+
+// operator!=/operator== - Allow mixed comparisons without dereferencing
+// the iterator, which could very likely be pointing to end().
+template<class T, class V, class W, class X, class Y>
+bool operator!=(T* LHS, const alist_iterator<V, W, X, Y> &RHS) {
+  return LHS != RHS.getNodeIterUnchecked().getNodePtrUnchecked()
+                                                            ->getElement((T*)0);
+}
+template<class T, class V, class W, class X, class Y>
+bool operator==(T* LHS, const alist_iterator<V, W, X, Y> &RHS) {
+  return LHS == RHS.getNodeIterUnchecked().getNodePtrUnchecked()
+                                                            ->getElement((T*)0);
+}
+
+// Allow alist_iterators to convert into pointers to a node automatically when
+// used by the dyn_cast, cast, isa mechanisms...
+
+template<class From> struct simplify_type;
+
+template<class V, class W, class X, class Y>
+struct simplify_type<alist_iterator<V, W, X, Y> > {
+  typedef alist_node<V, W> NodeTy;
+  typedef NodeTy* SimpleType;
+
+  static SimpleType
+  getSimplifiedValue(const alist_iterator<V, W, X, Y> &Node) {
+    return &*Node;
+  }
+};
+template<class V, class W, class X, class Y>
+struct simplify_type<const alist_iterator<V, W, X, Y> > {
+  typedef alist_node<V, W> NodeTy;
+  typedef NodeTy* SimpleType;
+
+  static SimpleType
+  getSimplifiedValue(const alist_iterator<V, W, X, Y> &Node) {
+    return &*Node;
+  }
+};
+
+/// Template traits for alist.  By specializing this template class, you
+/// can register custom actions to be run when a node is added to or removed
+/// from an alist. A common use of this is to update parent pointers.
+///
+template<class T, class LargestT = T>
+class alist_traits {
+  typedef alist_iterator<T, LargestT> iterator;
+
+public:
+  void addNodeToList(T *) {}
+  void removeNodeFromList(T *) {}
+  void transferNodesFromList(alist_traits &, iterator, iterator) {}
+  void deleteNode(T *E) { delete alist_node<T, LargestT>::getNode(E); }
+};
+
+/// alist - This class is an ilist-style container that automatically
+/// adds the next/prev pointers. It is designed to work in cooperation
+/// with <llvm/Support/Recycler.h>.
+///
+template<class T, class LargestT = T>
+class alist {
+  typedef alist_node<T, LargestT> NodeTy;
+
+public:
+  typedef typename ilist<NodeTy>::size_type size_type;
+
+private:
+  /// NodeListTraits - ilist traits for NodeList.
+  ///
+  struct NodeListTraits : ilist_traits<alist_node<T, LargestT> > {
+    alist_traits<T, LargestT> UserTraits;
+
+    void addNodeToList(NodeTy *N) {
+      UserTraits.addNodeToList(N->getElement((T*)0));
+    }
+    void removeNodeFromList(NodeTy *N) {
+      UserTraits.removeNodeFromList(N->getElement((T*)0));
+    }
+    void transferNodesFromList(iplist<NodeTy, NodeListTraits> &L2,
+                               ilist_iterator<NodeTy> first,
+                               ilist_iterator<NodeTy> last) {
+      UserTraits.transferNodesFromList(L2.UserTraits,
+                                       iterator(first),
+                                       iterator(last));
+    }
+  };
+
+  /// NodeList - Doubly-linked list of nodes that have constructed
+  /// contents and may be in active use.
+  ///
+  iplist<NodeTy, NodeListTraits> NodeList;
+
+public:
+  ~alist() { clear(); }
+
+  typedef alist_iterator<T, LargestT, T, ilist_iterator<NodeTy> >
+    iterator;
+  typedef alist_iterator<T, LargestT, const T, ilist_iterator<const NodeTy> >
+    const_iterator;
+  typedef std::reverse_iterator<iterator> reverse_iterator;
+  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+
+  iterator begin() { return iterator(NodeList.begin()); }
+  iterator end() { return iterator(NodeList.end()); }
+  const_iterator begin() const { return const_iterator(NodeList.begin()); }
+  const_iterator end() const { return const_iterator(NodeList.end()); }
+  reverse_iterator rbegin() { return reverse_iterator(NodeList.rbegin()); }
+  reverse_iterator rend() { return reverse_iterator(NodeList.rend()); }
+  const_reverse_iterator rbegin() const {
+    return const_reverse_iterator(NodeList.rbegin());
+  }
+  const_reverse_iterator rend() const {
+    return const_reverse_iterator(NodeList.rend());
+  }
+
+  typedef T& reference;
+  typedef const T& const_reference;
+  reference front() { return *NodeList.front().getElement((T*)0); }
+  reference back()  { return *NodeList.back().getElement((T*)0); }
+  const_reference front() const { return *NodeList.front().getElement((T*)0); }
+  const_reference back()  const { return *NodeList.back().getElement((T*)0); }
+
+  bool empty() const { return NodeList.empty(); }
+  size_type size() const { return NodeList.size(); }
+
+  void push_front(T *E) {
+    NodeTy *N = alist_node<T, LargestT>::getNode(E);
+    assert(N->getPrev() == 0);
+    assert(N->getNext() == 0);
+    NodeList.push_front(N);
+  }
+  void push_back(T *E) {
+    NodeTy *N = alist_node<T, LargestT>::getNode(E);
+    assert(N->getPrev() == 0);
+    assert(N->getNext() == 0);
+    NodeList.push_back(N);
+  }
+  iterator insert(iterator I, T *E) {
+    NodeTy *N = alist_node<T, LargestT>::getNode(E);
+    assert(N->getPrev() == 0);
+    assert(N->getNext() == 0);
+    return iterator(NodeList.insert(I.getNodeIterUnchecked(), N));
+  }
+  void splice(iterator where, alist &Other) {
+    NodeList.splice(where.getNodeIterUnchecked(), Other.NodeList);
+  }
+  void splice(iterator where, alist &Other, iterator From) {
+    NodeList.splice(where.getNodeIterUnchecked(), Other.NodeList,
+                    From.getNodeIterUnchecked());
+  }
+  void splice(iterator where, alist &Other, iterator From,
+              iterator To) {
+    NodeList.splice(where.getNodeIterUnchecked(), Other.NodeList,
+                    From.getNodeIterUnchecked(), To.getNodeIterUnchecked());
+  }
+
+  void pop_front() {
+    erase(NodeList.begin());
+  }
+  void pop_back() {
+    erase(prior(NodeList.end()));
+  }
+  iterator erase(iterator I) {
+    iterator Next = next(I);
+    NodeTy *N = NodeList.remove(I.getNodeIterUnchecked());
+    NodeList.UserTraits.deleteNode(N->getElement((T*)0));
+    return Next;
+  }
+  iterator erase(iterator first, iterator last) {
+    while (first != last)
+      first = erase(first);
+    return last;
+  }
+
+  T *remove(T *E) {
+    NodeTy *N = alist_node<T, LargestT>::getNode(E);
+    return NodeList.remove(N)->getElement((T*)0);
+  }
+
+  void clear() {
+    while (!empty()) pop_front();
+  }
+
+  alist_traits<T, LargestT> &getTraits() {
+    return NodeList.UserTraits;
+  }
+};
+
+}
+
+#endif

include/llvm/ADT/alist_node.h

@@ -0,0 +1,126 @@
+//==- llvm/ADT/alist_node.h - Next/Prev helper class for alist ---*- 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 alist_node class template, which is used by the alist
+// class template to provide next/prev pointers for arbitrary objects.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_ALIST_NODE_H
+#define LLVM_ADT_ALIST_NODE_H
+
+#include <cassert>
+#include "llvm/ADT/ilist.h"
+#include "llvm/Support/AlignOf.h"
+#include "llvm/Support/DataTypes.h"
+
+namespace llvm {
+
+/// alist_node - This is a utility class used by alist. It holds prev and next
+/// pointers for use with ilists, as well as storage for objects as large as
+/// LargestT, that are in T's inheritance tree.
+///
+template<class T, class LargestT = T>
+class alist_node {
+  alist_node *Prev, *Next;
+
+public:
+  alist_node() : Prev(0), Next(0) {}
+
+  alist_node *getPrev() const { return Prev; }
+  alist_node *getNext() const { return Next; }
+  void setPrev(alist_node *N) { Prev = N; }
+  void setNext(alist_node *N) { Next = N; }
+
+  union {
+    char Bytes[sizeof(LargestT)];
+    long long L;
+    void *P;
+  } Storage;
+
+  template<class SubClass>
+  SubClass *getElement(SubClass *) {
+    assert(sizeof(SubClass) <= sizeof(LargestT));
+    assert(unsigned(AlignOf<SubClass>::Alignment) <=
+           unsigned(AlignOf<LargestT>::Alignment));
+    return reinterpret_cast<SubClass*>(&Storage.Bytes);
+  }
+
+  template<class SubClass>
+  const SubClass *getElement(SubClass *) const {
+    assert(sizeof(SubClass) <= sizeof(LargestT));
+    assert(unsigned(AlignOf<SubClass>::Alignment) <=
+           unsigned(AlignOf<LargestT>::Alignment));
+    return reinterpret_cast<const SubClass*>(&Storage.Bytes);
+  }
+
+  // This code essentially does offsetof, but actual offsetof hits an ICE in
+  // GCC 4.0 relating to offsetof being used inside a template.
+  static alist_node* getNode(T *D) {
+    return reinterpret_cast<alist_node*>(reinterpret_cast<char*>(D) -
+                                                (uintptr_t)&getNull()->Storage);
+  }
+  static const alist_node* getNode(const T *D) {
+    return reinterpret_cast<alist_node*>(reinterpret_cast<char*>(D) -
+                                                (uintptr_t)&getNull()->Storage);
+  }
+private:
+  static alist_node* getNull() { return 0; }
+};
+
+// A specialization of ilist_traits for alist_nodes.
+template<class T, class LargestT>
+class ilist_traits<alist_node<T, LargestT> > {
+  typedef alist_node<T, LargestT> NodeTy;
+
+protected:
+  // Allocate a sentinel inside the traits class. This works
+  // because iplist carries an instance of the traits class.
+  NodeTy Sentinel;
+
+public:
+  static NodeTy *getPrev(NodeTy *N) { return N->getPrev(); }
+  static NodeTy *getNext(NodeTy *N) { return N->getNext(); }
+  static const NodeTy *getPrev(const NodeTy *N) { return N->getPrev(); }
+  static const NodeTy *getNext(const NodeTy *N) { return N->getNext(); }
+
+  static void setPrev(NodeTy *N, NodeTy *Prev) { N->setPrev(Prev); }
+  static void setNext(NodeTy *N, NodeTy *Next) { N->setNext(Next); }
+
+  NodeTy *createSentinel() const {
+    assert(Sentinel.getPrev() == 0);
+    assert(Sentinel.getNext() == 0);
+    return const_cast<NodeTy*>(&Sentinel);
+  }
+
+  void destroySentinel(NodeTy *N) {
+    assert(N == &Sentinel);
+    Sentinel.setPrev(0);
+    Sentinel.setNext(0);
+  }
+
+  void addNodeToList(NodeTy *N) {}
+  void removeNodeFromList(NodeTy *N) {}
+  void transferNodesFromList(iplist<NodeTy, ilist_traits> &L2,
+                             ilist_iterator<NodeTy> first,
+                             ilist_iterator<NodeTy> last) {}
+
+  // Ideally we wouldn't implement this, but ilist's clear calls it,
+  // which is called from ilist's destructor. We won't ever call
+  // either of those with a non-empty list, but statically this
+  // method needs to exist.
+  void deleteNode(NodeTy *N) { assert(0); }
+
+private:
+  static NodeTy *createNode(const NodeTy &V); // do not implement
+};
+
+}
+
+#endif

include/llvm/ADT/ilist.h

@@ -60,6 +60,7 @@ struct ilist_traits {
   static void setNext(NodeTy *N, NodeTy *Next) { N->setNext(Next); }
 
   static NodeTy *createNode(const NodeTy &V) { return new NodeTy(V); }
+  static void deleteNode(NodeTy *V) { delete V; }
 
   static NodeTy *createSentinel() { return new NodeTy(); }
   static void destroySentinel(NodeTy *N) { delete N; }
@@ -121,8 +122,7 @@ public:
     assert(Traits::getNext(NodePtr) != 0 && "Dereferencing end()!");
     return *NodePtr;
   }
-  pointer operator->() { return &operator*(); }
+  pointer operator->() const { return &operator*(); }
-  const pointer operator->() const { return &operator*(); }
 
   // Comparison operators
   bool operator==(const ilist_iterator &RHS) const {
@@ -380,7 +380,7 @@ public:
 
   // erase - remove a node from the controlled sequence... and delete it.
   iterator erase(iterator where) {
-    delete remove(where);
+    deleteNode(remove(where));
     return where;
   }
 

include/llvm/Support/Recycler.h

@@ -0,0 +1,97 @@
+//==- llvm/Support/Recycler.h - Recycling Allocator --------------*- 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 Recycler class template.  See the doxygen comment for
+// Recycler for more details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_RECYCLER_H
+#define LLVM_SUPPORT_RECYCLER_H
+
+#include <cassert>
+#include "llvm/ADT/alist_node.h"
+
+namespace llvm {
+
+/// PrintRecyclingAllocatorStats - Helper for RecyclingAllocator for
+/// printing statistics.
+///
+void PrintRecyclerStats(size_t LargestTypeSize, size_t FreeListSize);
+
+/// Recycler - This class manages a linked-list of deallocated nodes
+/// and facilitates reusing deallocated memory in place of allocating
+/// new memory. The objects it allocates are stored in alist_node
+/// containers, so they may be used in alists.
+///
+template<class T, class LargestT = T>
+class Recycler {
+  typedef alist_node<T, LargestT> NodeTy;
+
+  /// FreeListTraits - ilist traits for FreeList.
+  ///
+  struct FreeListTraits : ilist_traits<alist_node<T, LargestT> > {
+    NodeTy &getSentinel() { return this->Sentinel; }
+  };
+
+  /// FreeList - Doubly-linked list of nodes that have deleted contents and
+  /// are not in active use.
+  ///
+  iplist<NodeTy, FreeListTraits> FreeList;
+
+  /// CreateNewNode - Allocate a new node object and initialize its
+  /// prev and next pointers to 0.
+  ///
+  template<class AllocatorType>
+  NodeTy *CreateNewNode(AllocatorType &Allocator) {
+    // Note that we're calling new on the *node*, to initialize its
+    // Next/Prev pointers, not new on the end-user object.
+    return new (Allocator.Allocate<NodeTy>()) NodeTy();
+  }
+
+public:
+  ~Recycler() { assert(FreeList.empty()); }
+
+  template<class AllocatorType>
+  void clear(AllocatorType &Allocator) {
+    while (!FreeList.empty())
+      Allocator.Deallocate(FreeList.remove(FreeList.begin()));
+  }
+
+  template<class SubClass, class AllocatorType>
+  SubClass *Allocate(AllocatorType &Allocator) {
+    NodeTy *N = !FreeList.empty() ?
+                FreeList.remove(FreeList.front()) :
+                CreateNewNode(Allocator);
+    assert(N->getPrev() == 0);
+    assert(N->getNext() == 0);
+    return N->getElement((SubClass*)0);
+  }
+
+  template<class AllocatorType>
+  T *Allocate(AllocatorType &Allocator) {
+    return Allocate<T>(Allocator);
+  }
+
+  template<class SubClass, class AllocatorType>
+  void Deallocate(AllocatorType &Allocator, SubClass* Element) {
+    NodeTy *N = NodeTy::getNode(Element);
+    assert(N->getPrev() == 0);
+    assert(N->getNext() == 0);
+    FreeList.push_front(N);
+  }
+
+  void PrintStats() {
+    PrintRecyclerStats(sizeof(LargestT), FreeList.size());
+  }
+};
+
+}
+
+#endif

include/llvm/Support/RecyclingAllocator.h

@@ -0,0 +1,60 @@
+//==- llvm/Support/RecyclingAllocator.h - Recycling Allocator ----*- 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 RecyclingAllocator class.  See the doxygen comment for
+// RecyclingAllocator for more details on the implementation.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_RECYCLINGALLOCATOR_H
+#define LLVM_SUPPORT_RECYCLINGALLOCATOR_H
+
+#include <cassert>
+#include "llvm/Support/Recycler.h"
+#include "llvm/ADT/STLExtras.h"
+
+namespace llvm {
+
+/// RecyclingAllocator - This class wraps an Allocator, adding the
+/// functionality of recycling deleted objects.
+///
+template<class AllocatorType, class T, class LargestT = T>
+class RecyclingAllocator {
+private:
+  /// Base - Implementation details.
+  ///
+  Recycler<T, LargestT> Base;
+
+  /// Allocator - The wrapped allocator.
+  ///
+  AllocatorType Allocator;
+
+public:
+  ~RecyclingAllocator() { Base.clear(Allocator); }
+
+  /// Allocate - Return a pointer to storage for an object of type
+  /// SubClass. The storage may be either newly allocated or recycled.
+  ///
+  template<class SubClass>
+  SubClass *Allocate() { return Base.Allocate<SubClass>(Allocator); }
+
+  T *Allocate() { return Base.Allocate(Allocator); }
+
+  /// Deallocate - Release storage for the pointed-to object. The
+  /// storage will be kept track of and may be recycled.
+  ///
+  template<class SubClass>
+  void Deallocate(SubClass* E) { return Base.Deallocate(Allocator, E); }
+
+  void PrintStats() { Base.PrintStats(); }
+};
+
+}
+
+#endif

include/llvm/SymbolTableListTraits.h

@@ -57,6 +57,10 @@ public:
     return V->getNext();
   }
 
+  void deleteNode(ValueSubClass *V) {
+    delete V;
+  }
+
   static void setPrev(ValueSubClass *V, ValueSubClass *P) { V->setPrev(P); }
   static void setNext(ValueSubClass *V, ValueSubClass *N) { V->setNext(N); }
 

lib/Support/Allocator.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/Recycler.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/Streams.h"
 #include <ostream>
@@ -130,3 +131,9 @@ void BumpPtrAllocator::PrintStats() const {
   cerr << "\nNumber of memory regions: " << NumRegions << "\n";
   cerr << "Bytes allocated: " << BytesUsed << "\n";
 }
+
+void llvm::PrintRecyclerStats(size_t LargestTypeSize,
+                              size_t FreeListSize) {
+  cerr << "Recycler element size: " << LargestTypeSize << '\n';
+  cerr << "Number of elements free for recycling: " << FreeListSize << '\n';
+}