Completely rewrite support for the Value::use_* list. Now, all operations on

this list (except use_size()) are constant time.  Before the killUse method
(used whenever something stopped using a value) was linear time, and thus
very very slow for large programs.

This speeds GCCAS up _substantially_ on large programs: almost 2x for 176.gcc:

176.gcc:     77.07s -> 37.38s
177.mesa:     7.59s ->  5.57s
252.eon:     21.02s -> 19.52s (*)
253.perlbmk: 11.40s -> 13.05s
254.gap:      7.25s -> 7.42s

252.eon would speed up a whole lot more, but optimization time is being
dominated by the inlining pass, which needs to be fixed.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9159 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 185 insertions, 65 deletions

diff --git a/include/llvm/Use.h b/include/llvm/Use.h
new file mode 100644
index 0000000000..a0f920d2e5
--- /dev/null
+++ b/include/llvm/Use.h
@@ -0,0 +1,146 @@
+//===-- llvm/Use.h - Definition of the Use class ----------------*- C++ -*-===//
+//
+// This defines the Use class.  The Use class represents the operand of an
+// instruction or some other User instance which refers to a Value.  The Use
+// class keeps the "use list" of the referenced value up to date.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_USE_H
+#define LLVM_USE_H
+
+#include "Support/ilist"
+template<typename NodeTy> struct ilist_traits;
+class Value;
+class User;
+
+
+//===----------------------------------------------------------------------===//
+//                                  Use Class
+//===----------------------------------------------------------------------===//
+
+// Use is here to make keeping the "use" list of a Value up-to-date really easy.
+//
+class Use {
+  Value *Val;
+  User *U;
+  Use *Prev, *Next;
+  friend class ilist_traits<Use>;
+public:
+  inline Use(Value *v, User *user);
+  inline Use(const Use &u);
+  inline ~Use();
+
+  operator Value*() const { return Val; }
+  Value *get() const { return Val; }
+  User *getUser() const { return U; }
+
+  inline void set(Value *Val);
+
+  Value *operator=(Value *RHS) {
+    set(RHS);
+    return RHS;
+  }
+  const Use &operator=(const Use &RHS) {
+    set(RHS.Val);
+    return *this;
+  }
+
+        Value *operator->()       { return Val; }
+  const Value *operator->() const { return Val; }
+};
+
+template<>
+struct ilist_traits<Use> {
+  static Use *getPrev(Use *N) { return N->Prev; }
+  static Use *getNext(Use *N) { return N->Next; }
+  static const Use *getPrev(const Use *N) { return N->Prev; }
+  static const Use *getNext(const Use *N) { return N->Next; }
+  static void setPrev(Use *N, Use *Prev) { N->Prev = Prev; }
+  static void setNext(Use *N, Use *Next) { N->Next = Next; }
+
+  // createNode - this is used to create the end marker for the use list
+  static Use *createNode() { return new Use(0,0); }
+
+  void addNodeToList(Use *NTy) {}
+  void removeNodeFromList(Use *NTy) {}
+  void transferNodesFromList(iplist<Use, ilist_traits> &L2,
+                             ilist_iterator<Use> first,
+                             ilist_iterator<Use> last) {}
+};
+
+
+template<> struct simplify_type<Use> {
+  typedef Value* SimpleType;
+  static SimpleType getSimplifiedValue(const Use &Val) {
+    return (SimpleType)Val.get();
+  }
+};
+template<> struct simplify_type<const Use> {
+  typedef Value* SimpleType;
+  static SimpleType getSimplifiedValue(const Use &Val) {
+    return (SimpleType)Val.get();
+  }
+};
+
+struct UseListIteratorWrapper : public iplist<Use>::iterator {
+  typedef iplist<Use>::iterator Super;
+  UseListIteratorWrapper() {}
+  UseListIteratorWrapper(const Super &RHS) : Super(RHS) {}
+
+  UseListIteratorWrapper &operator=(const Super &RHS) {
+    Super::operator=(RHS);
+    return *this;
+  }
+
+  inline User *operator*() const;
+  User *operator->() const { return operator*(); }
+
+  UseListIteratorWrapper operator--() { return Super::operator--(); }
+  UseListIteratorWrapper operator++() { return Super::operator++(); }
+
+  UseListIteratorWrapper operator--(int) {    // postdecrement operators...
+    UseListIteratorWrapper tmp = *this;
+    --*this;
+    return tmp;
+  }
+  UseListIteratorWrapper operator++(int) {    // postincrement operators...
+    UseListIteratorWrapper tmp = *this;
+    ++*this;
+    return tmp;
+  }
+};
+
+struct UseListConstIteratorWrapper : public iplist<Use>::const_iterator {
+  typedef iplist<Use>::const_iterator Super;
+  UseListConstIteratorWrapper() {}
+  UseListConstIteratorWrapper(const Super &RHS) : Super(RHS) {}
+
+  // Allow conversion from non-const to const iterators
+  UseListConstIteratorWrapper(const UseListIteratorWrapper &RHS) : Super(RHS) {}
+  UseListConstIteratorWrapper(const iplist<Use>::iterator &RHS) : Super(RHS) {}
+
+  UseListConstIteratorWrapper &operator=(const Super &RHS) {
+    Super::operator=(RHS);
+    return *this;
+  }
+
+  inline const User *operator*() const;
+  const User *operator->() const { return operator*(); }
+
+  UseListConstIteratorWrapper operator--() { return Super::operator--(); }
+  UseListConstIteratorWrapper operator++() { return Super::operator++(); }
+
+  UseListConstIteratorWrapper operator--(int) {    // postdecrement operators...
+    UseListConstIteratorWrapper tmp = *this;
+    --*this;
+    return tmp;
+  }
+  UseListConstIteratorWrapper operator++(int) {    // postincrement operators...
+    UseListConstIteratorWrapper tmp = *this;
+    ++*this;
+    return tmp;
+  }
+};
+
+#endif
diff --git a/include/llvm/Value.h b/include/llvm/Value.h
index 7b50c94954..5fa1497dae 100644
--- a/include/llvm/Value.h
+++ b/include/llvm/Value.h
@@ -11,12 +11,11 @@
 #define LLVM_VALUE_H
 
 #include "llvm/AbstractTypeUser.h"
+#include "llvm/Use.h"
 #include "Support/Annotation.h"
 #include "Support/Casting.h"
 #include <iostream>
-#include <vector>
 
-class User;
 class Type;
 class Constant;
 class Argument;
@@ -46,7 +45,7 @@ struct Value : public Annotable {         // Values are annotable
   };
 
 private:
-  std::vector<User *> Uses;
+  iplist<Use> Uses;
   std::string Name;
   PATypeHolder Ty;
   ValueTy VTy;
@@ -94,8 +93,8 @@ public:
   //----------------------------------------------------------------------
   // Methods for handling the vector of uses of this Value.
   //
-  typedef std::vector<User*>::iterator       use_iterator;
-  typedef std::vector<User*>::const_iterator use_const_iterator;
+  typedef UseListIteratorWrapper      use_iterator;
+  typedef UseListConstIteratorWrapper use_const_iterator;
 
   unsigned           use_size()  const { return Uses.size();  }
   bool               use_empty() const { return Uses.empty(); }
@@ -103,17 +102,23 @@ public:
   use_const_iterator use_begin() const { return Uses.begin(); }
   use_iterator       use_end()         { return Uses.end();   }
   use_const_iterator use_end()   const { return Uses.end();   }
-  User              *use_back()        { return Uses.back();  }
-  const User        *use_back()  const { return Uses.back();  }
+  User             *use_back()         { return Uses.back().getUser(); }
+  const User       *use_back()  const  { return Uses.back().getUser(); }
 
-  /// hasOneUse - Return true if there is exactly one user of this value.
+  /// hasOneUse - Return true if there is exactly one user of this value.  This
+  /// is specialized because it is a common request and does not require
+  /// traversing the whole use list.
   ///
-  bool hasOneUse() const { return use_size() == 1; }
+  bool hasOneUse() const {
+    iplist<Use>::const_iterator I = Uses.begin(), E = Uses.end();
+    if (I == E) return false;
+    return ++I == E;
+  }
 
-  /// addUse/killUse - These two methods should only be used by the Use class
-  /// below.
-  void addUse(User *I)      { Uses.push_back(I); }
-  void killUse(User *I);
+  /// addUse/killUse - These two methods should only be used by the Use class.
+  ///
+  void addUse(Use &U)  { Uses.push_back(&U); }
+  void killUse(Use &U) { Uses.remove(&U); }
 };
 
 inline std::ostream &operator<<(std::ostream &OS, const Value *V) {
@@ -130,64 +135,33 @@ inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
 }
 
 
-//===----------------------------------------------------------------------===//
-//                                  Use Class
-//===----------------------------------------------------------------------===//
+inline User *UseListIteratorWrapper::operator*() const {
+  return Super::operator*().getUser();
+}
 
-// Use is here to make keeping the "use" list of a Value up-to-date really easy.
-//
-class Use {
-  Value *Val;
-  User *U;
-public:
-  inline Use(Value *v, User *user) {
-    Val = v; U = user;
-    if (Val) Val->addUse(U);
-  }
+inline const User *UseListConstIteratorWrapper::operator*() const {
+  return Super::operator*().getUser();
+}
 
-  inline Use(const Use &user) {
-    Val = 0;
-    U = user.U;
-    operator=(user.Val);
-  }
-  inline ~Use() { if (Val) Val->killUse(U); }
-  inline operator Value*() const { return Val; }
-
-  inline Value *operator=(Value *V) { 
-    if (Val) Val->killUse(U);
-    Val = V;
-    if (V) V->addUse(U);
-    return V;
-  }
 
-  inline       Value *operator->()       { return Val; }
-  inline const Value *operator->() const { return Val; }
+Use::Use(Value *v, User *user) : Val(v), U(user) {
+  if (Val) Val->addUse(*this);
+}
+
+Use::Use(const Use &u) : Val(u.Val), U(u.U) {
+  if (Val) Val->addUse(*this);
+}
 
-  inline       Value *get()       { return Val; }
-  inline const Value *get() const { return Val; }
+Use::~Use() {
+  if (Val) Val->killUse(*this);
+}
 
-  inline const Use &operator=(const Use &user) {
-    if (Val) Val->killUse(U);
-    Val = user.Val;
-    Val->addUse(U);
-    return *this;
-  }
-};
+void Use::set(Value *V) { 
+  if (Val) Val->killUse(*this);
+  Val = V;
+  if (V) V->addUse(*this);
+}
 
-template<> struct simplify_type<Use> {
-  typedef Value* SimpleType;
-  
-  static SimpleType getSimplifiedValue(const Use &Val) {
-    return (SimpleType)Val.get();
-  }
-};
-template<> struct simplify_type<const Use> {
-  typedef Value* SimpleType;
-  
-  static SimpleType getSimplifiedValue(const Use &Val) {
-    return (SimpleType)Val.get();
-  }
-};
 
 // isa - Provide some specializations of isa so that we don't have to include
 // the subtype header files to test to see if the value is a subclass...