Simplify the allocation and freeing of Users' operand lists, now that

every BranchInst has a fixed number of operands.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123027 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 4 insertions, 69 deletions

diff --git a/include/llvm/Instructions.h b/include/llvm/Instructions.h
index 626dd0ee45..7a53c429a1 100644
--- a/include/llvm/Instructions.h
+++ b/include/llvm/Instructions.h
@@ -2068,22 +2068,20 @@ protected:
   virtual BranchInst *clone_impl() const;
 public:
   static BranchInst *Create(BasicBlock *IfTrue, Instruction *InsertBefore = 0) {
-    return new(1, true) BranchInst(IfTrue, InsertBefore);
+    return new(1) BranchInst(IfTrue, InsertBefore);
   }
   static BranchInst *Create(BasicBlock *IfTrue, BasicBlock *IfFalse,
                             Value *Cond, Instruction *InsertBefore = 0) {
     return new(3) BranchInst(IfTrue, IfFalse, Cond, InsertBefore);
   }
   static BranchInst *Create(BasicBlock *IfTrue, BasicBlock *InsertAtEnd) {
-    return new(1, true) BranchInst(IfTrue, InsertAtEnd);
+    return new(1) BranchInst(IfTrue, InsertAtEnd);
   }
   static BranchInst *Create(BasicBlock *IfTrue, BasicBlock *IfFalse,
                             Value *Cond, BasicBlock *InsertAtEnd) {
     return new(3) BranchInst(IfTrue, IfFalse, Cond, InsertAtEnd);
   }
 
-  ~BranchInst();
-
   /// Transparently provide more efficient getOperand methods.
   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 
diff --git a/include/llvm/Use.h b/include/llvm/Use.h
index e1ebc6a51b..507504ecdc 100644
--- a/include/llvm/Use.h
+++ b/include/llvm/Use.h
@@ -112,8 +112,6 @@ public:
   /// a User changes.
   static void zap(Use *Start, const Use *Stop, bool del = false);
 
-  /// getPrefix - Return deletable pointer if appropriate
-  Use *getPrefix();
 private:
   const Use* getImpliedUser() const;
   static Use *initTags(Use *Start, Use *Stop, ptrdiff_t Done = 0);
diff --git a/include/llvm/User.h b/include/llvm/User.h
index f8277952ee..1b215e395e 100644
--- a/include/llvm/User.h
+++ b/include/llvm/User.h
@@ -61,7 +61,6 @@ protected:
   unsigned NumOperands;
 
   void *operator new(size_t s, unsigned Us);
-  void *operator new(size_t s, unsigned Us, bool Prefix);
   User(const Type *ty, unsigned vty, Use *OpList, unsigned NumOps)
     : Value(ty, vty), OperandList(OpList), NumOperands(NumOps) {}
   Use *allocHungoffUses(unsigned) const;
@@ -74,8 +73,7 @@ protected:
   }
 public:
   ~User() {
-    if ((intptr_t(OperandList) & 1) == 0)
-      Use::zap(OperandList, OperandList + NumOperands);
+    Use::zap(OperandList, OperandList + NumOperands);
   }
   /// operator delete - free memory allocated for User and Use objects
   void operator delete(void *Usr);
diff --git a/lib/VMCore/Instructions.cpp b/lib/VMCore/Instructions.cpp
index f465907735..33acd0d040 100644
--- a/lib/VMCore/Instructions.cpp
+++ b/lib/VMCore/Instructions.cpp
@@ -730,31 +730,6 @@ BranchInst::BranchInst(const BranchInst &BI) :
   SubclassOptionalData = BI.SubclassOptionalData;
 }
 
-
-Use* Use::getPrefix() {
-  PointerIntPair<Use**, 2, PrevPtrTag> &PotentialPrefix(this[-1].Prev);
-  if (PotentialPrefix.getOpaqueValue())
-    return 0;
-
-  return reinterpret_cast<Use*>((char*)&PotentialPrefix + 1);
-}
-
-BranchInst::~BranchInst() {
-  if (NumOperands == 1) {
-    if (Use *Prefix = OperandList->getPrefix()) {
-      Op<-1>() = 0;
-      //
-      // mark OperandList to have a special value for scrutiny
-      // by baseclass destructors and operator delete
-      OperandList = Prefix;
-    } else {
-      NumOperands = 3;
-      OperandList = op_begin();
-    }
-  }
-}
-
-
 BasicBlock *BranchInst::getSuccessorV(unsigned idx) const {
   return getSuccessor(idx);
 }
@@ -3329,8 +3304,7 @@ ReturnInst *ReturnInst::clone_impl() const {
 }
 
 BranchInst *BranchInst::clone_impl() const {
-  unsigned Ops(getNumOperands());
-  return new(Ops, Ops == 1) BranchInst(*this);
+  return new(getNumOperands()) BranchInst(*this);
 }
 
 SwitchInst *SwitchInst::clone_impl() const {
diff --git a/lib/VMCore/Use.cpp b/lib/VMCore/Use.cpp
index fec710b394..5dfe650685 100644
--- a/lib/VMCore/Use.cpp
+++ b/lib/VMCore/Use.cpp
@@ -191,31 +191,6 @@ void *User::operator new(size_t s, unsigned Us) {
   return Obj;
 }
 
-/// Prefixed allocation - just before the first Use, allocate a NULL pointer.
-/// The destructor can detect its presence and readjust the OperandList
-/// for deletition.
-///
-void *User::operator new(size_t s, unsigned Us, bool Prefix) {
-  // currently prefixed allocation only admissible for
-  // unconditional branch instructions
-  if (!Prefix)
-    return operator new(s, Us);
-
-  assert(Us == 1 && "Other than one Use allocated?");
-  typedef PointerIntPair<void*, 2, Use::PrevPtrTag> TaggedPrefix;
-  void *Raw = ::operator new(s + sizeof(TaggedPrefix) + sizeof(Use) * Us);
-  TaggedPrefix *Pre = static_cast<TaggedPrefix*>(Raw);
-  Pre->setFromOpaqueValue(0);
-  void *Storage = Pre + 1; // skip over prefix
-  Use *Start = static_cast<Use*>(Storage);
-  Use *End = Start + Us;
-  User *Obj = reinterpret_cast<User*>(End);
-  Obj->OperandList = Start;
-  Obj->NumOperands = Us;
-  Use::initTags(Start, End);
-  return Obj;
-}
-
 //===----------------------------------------------------------------------===//
 //                         User operator delete Implementation
 //===----------------------------------------------------------------------===//
@@ -230,14 +205,6 @@ void User::operator delete(void *Usr) {
     return;
   }
   //
-  // check for the flag whether the destructor has detected a prefixed
-  // allocation, in which case we remove the flag and delete starting
-  // at OperandList
-  if (reinterpret_cast<intptr_t>(Start->OperandList) & 1) {
-    ::operator delete(reinterpret_cast<char*>(Start->OperandList) - 1);
-    return;
-  }
-  //
   // in all other cases just delete the nullary User (covers hung-off
   // uses also
   ::operator delete(Usr);