Reinstate r133435 and r133449 (reverted in r133499) now that the clang

self-hosted build failure has been fixed (r133512).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133513 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 61 insertions, 34 deletions

diff --git a/include/llvm/BasicBlock.h b/include/llvm/BasicBlock.h
index 7e7c9e7694..b02c249c7e 100644
--- a/include/llvm/BasicBlock.h
+++ b/include/llvm/BasicBlock.h
@@ -110,7 +110,7 @@ public:
         Function *getParent()       { return Parent; }
 
   /// use_back - Specialize the methods defined in Value, as we know that an
-  /// BasicBlock can only be used by Users (specifically PHI nodes, terminators,
+  /// BasicBlock can only be used by Users (specifically terminators
   /// and BlockAddress's).
   User       *use_back()       { return cast<User>(*use_begin());}
   const User *use_back() const { return cast<User>(*use_begin());}
@@ -248,6 +248,10 @@ public:
   /// other than direct branches, switches, etc. to it.
   bool hasAddressTaken() const { return getSubclassDataFromValue() != 0; }
 
+  /// replaceSuccessorsPhiUsesWith - Update all phi nodes in all our successors
+  /// to refer to basic block New instead of to us.
+  void replaceSuccessorsPhiUsesWith(BasicBlock *New);
+
 private:
   /// AdjustBlockAddressRefCount - BasicBlock stores the number of BlockAddress
   /// objects using it.  This is almost always 0, sometimes one, possibly but
diff --git a/include/llvm/Instructions.h b/include/llvm/Instructions.h
index 54dfe3957f..cc3801043e 100644
--- a/include/llvm/Instructions.h
+++ b/include/llvm/Instructions.h
@@ -1814,7 +1814,7 @@ class PHINode : public Instruction {
   explicit PHINode(const Type *Ty, unsigned NumReservedValues,
                    const Twine &NameStr = "", Instruction *InsertBefore = 0)
     : Instruction(Ty, Instruction::PHI, 0, 0, InsertBefore),
-      ReservedSpace(NumReservedValues * 2) {
+      ReservedSpace(NumReservedValues) {
     setName(NameStr);
     OperandList = allocHungoffUses(ReservedSpace);
   }
@@ -1822,11 +1822,16 @@ class PHINode : public Instruction {
   PHINode(const Type *Ty, unsigned NumReservedValues, const Twine &NameStr,
           BasicBlock *InsertAtEnd)
     : Instruction(Ty, Instruction::PHI, 0, 0, InsertAtEnd),
-      ReservedSpace(NumReservedValues * 2) {
+      ReservedSpace(NumReservedValues) {
     setName(NameStr);
     OperandList = allocHungoffUses(ReservedSpace);
   }
 protected:
+  // allocHungoffUses - this is more complicated than the generic
+  // User::allocHungoffUses, because we have to allocate Uses for the incoming
+  // values and pointers to the incoming blocks, all in one allocation.
+  Use *allocHungoffUses(unsigned) const;
+
   virtual PHINode *clone_impl() const;
 public:
   /// Constructors - NumReservedValues is a hint for the number of incoming
@@ -1845,32 +1850,55 @@ public:
   /// Provide fast operand accessors
   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 
+  // Block iterator interface. This provides access to the list of incoming
+  // basic blocks, which parallels the list of incoming values.
+
+  typedef BasicBlock **block_iterator;
+  typedef BasicBlock * const *const_block_iterator;
+
+  block_iterator block_begin() {
+    Use::UserRef *ref =
+      reinterpret_cast<Use::UserRef*>(op_begin() + ReservedSpace);
+    return reinterpret_cast<block_iterator>(ref + 1);
+  }
+
+  const_block_iterator block_begin() const {
+    const Use::UserRef *ref =
+      reinterpret_cast<const Use::UserRef*>(op_begin() + ReservedSpace);
+    return reinterpret_cast<const_block_iterator>(ref + 1);
+  }
+
+  block_iterator block_end() {
+    return block_begin() + getNumOperands();
+  }
+
+  const_block_iterator block_end() const {
+    return block_begin() + getNumOperands();
+  }
+
   /// getNumIncomingValues - Return the number of incoming edges
   ///
-  unsigned getNumIncomingValues() const { return getNumOperands()/2; }
+  unsigned getNumIncomingValues() const { return getNumOperands(); }
 
   /// getIncomingValue - Return incoming value number x
   ///
   Value *getIncomingValue(unsigned i) const {
-    assert(i*2 < getNumOperands() && "Invalid value number!");
-    return getOperand(i*2);
+    return getOperand(i);
   }
   void setIncomingValue(unsigned i, Value *V) {
-    assert(i*2 < getNumOperands() && "Invalid value number!");
-    setOperand(i*2, V);
+    setOperand(i, V);
   }
   static unsigned getOperandNumForIncomingValue(unsigned i) {
-    return i*2;
+    return i;
   }
   static unsigned getIncomingValueNumForOperand(unsigned i) {
-    assert(i % 2 == 0 && "Invalid incoming-value operand index!");
-    return i/2;
+    return i;
   }
 
   /// getIncomingBlock - Return incoming basic block number @p i.
   ///
   BasicBlock *getIncomingBlock(unsigned i) const {
-    return cast<BasicBlock>(getOperand(i*2+1));
+    return block_begin()[i];
   }
 
   /// getIncomingBlock - Return incoming basic block corresponding
@@ -1878,7 +1906,7 @@ public:
   ///
   BasicBlock *getIncomingBlock(const Use &U) const {
     assert(this == U.getUser() && "Iterator doesn't point to PHI's Uses?");
-    return cast<BasicBlock>((&U + 1)->get());
+    return getIncomingBlock(&U - op_begin());
   }
 
   /// getIncomingBlock - Return incoming basic block corresponding
@@ -1889,16 +1917,8 @@ public:
     return getIncomingBlock(I.getUse());
   }
 
-
   void setIncomingBlock(unsigned i, BasicBlock *BB) {
-    setOperand(i*2+1, (Value*)BB);
-  }
-  static unsigned getOperandNumForIncomingBlock(unsigned i) {
-    return i*2+1;
-  }
-  static unsigned getIncomingBlockNumForOperand(unsigned i) {
-    assert(i % 2 == 1 && "Invalid incoming-block operand index!");
-    return i/2;
+    block_begin()[i] = BB;
   }
 
   /// addIncoming - Add an incoming value to the end of the PHI list
@@ -1908,13 +1928,12 @@ public:
     assert(BB && "PHI node got a null basic block!");
     assert(getType() == V->getType() &&
            "All operands to PHI node must be the same type as the PHI node!");
-    unsigned OpNo = NumOperands;
-    if (OpNo+2 > ReservedSpace)
+    if (NumOperands == ReservedSpace)
       growOperands();  // Get more space!
     // Initialize some new operands.
-    NumOperands = OpNo+2;
-    OperandList[OpNo] = V;
-    OperandList[OpNo+1] = (Value*)BB;
+    ++NumOperands;
+    setIncomingValue(NumOperands - 1, V);
+    setIncomingBlock(NumOperands - 1, BB);
   }
 
   /// removeIncomingValue - Remove an incoming value.  This is useful if a
@@ -1937,14 +1956,16 @@ public:
   /// block in the value list for this PHI.  Returns -1 if no instance.
   ///
   int getBasicBlockIndex(const BasicBlock *BB) const {
-    Use *OL = OperandList;
-    for (unsigned i = 0, e = getNumOperands(); i != e; i += 2)
-      if (OL[i+1].get() == (const Value*)BB) return i/2;
+    for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
+      if (block_begin()[i] == BB)
+        return i;
     return -1;
   }
 
   Value *getIncomingValueForBlock(const BasicBlock *BB) const {
-    return getIncomingValue(getBasicBlockIndex(BB));
+    int Idx = getBasicBlockIndex(BB);
+    assert(Idx >= 0 && "Invalid basic block argument!");
+    return getIncomingValue(Idx);
   }
 
   /// hasConstantValue - If the specified PHI node always merges together the
diff --git a/include/llvm/Support/CFG.h b/include/llvm/Support/CFG.h
index d2ea12364e..7e193ff15e 100644
--- a/include/llvm/Support/CFG.h
+++ b/include/llvm/Support/CFG.h
@@ -33,7 +33,7 @@ class PredIterator : public std::iterator<std::forward_iterator_tag,
   USE_iterator It;
 
   inline void advancePastNonTerminators() {
-    // Loop to ignore non terminator uses (for example PHI nodes).
+    // Loop to ignore non terminator uses (for example BlockAddresses).
     while (!It.atEnd() && !isa<TerminatorInst>(*It))
       ++It;
   }
diff --git a/include/llvm/Use.h b/include/llvm/Use.h
index 1bdacb48f4..a496325c1f 100644
--- a/include/llvm/Use.h
+++ b/include/llvm/Use.h
@@ -112,13 +112,16 @@ public:
   Use *getNext() const { return Next; }
 
   
+  /// initTags - initialize the waymarking tags on an array of Uses, so that
+  /// getUser() can find the User from any of those Uses.
+  static Use *initTags(Use *Start, Use *Stop);
+
   /// zap - This is used to destroy Use operands when the number of operands of
   /// a User changes.
   static void zap(Use *Start, const Use *Stop, bool del = false);
 
 private:
   const Use* getImpliedUser() const;
-  static Use *initTags(Use *Start, Use *Stop);
   
   Value *Val;
   Use *Next;
@@ -140,7 +143,6 @@ private:
   }
 
   friend class Value;
-  friend class User;
 };
 
 // simplify_type - Allow clients to treat uses just like values when using