Reapply commit 112699, speculatively reverted by echristo, since

I'm sure it is harmless.  Original commit message:
If PrototypeValue is erased in the middle of using the SSAUpdator
then the SSAUpdator may access freed memory.  Instead, simply pass
in the type and name explicitly, which is all that was used anyway.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112810 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 12 insertions, 14 deletions

diff --git a/lib/Transforms/Utils/LCSSA.cpp b/lib/Transforms/Utils/LCSSA.cpp
index 409b4bd..275b265 100644
--- a/lib/Transforms/Utils/LCSSA.cpp
+++ b/lib/Transforms/Utils/LCSSA.cpp
@@ -206,7 +206,7 @@ bool LCSSA::ProcessInstruction(Instruction *Inst,
   DomTreeNode *DomNode = DT->getNode(DomBB);
 
   SSAUpdater SSAUpdate;
-  SSAUpdate.Initialize(Inst);
+  SSAUpdate.Initialize(Inst->getType(), Inst->getName());
   
   // Insert the LCSSA phi's into all of the exit blocks dominated by the
   // value, and add them to the Phi's map.
diff --git a/lib/Transforms/Utils/SSAUpdater.cpp b/lib/Transforms/Utils/SSAUpdater.cpp
index 9dc2a1e..c855988 100644
--- a/lib/Transforms/Utils/SSAUpdater.cpp
+++ b/lib/Transforms/Utils/SSAUpdater.cpp
@@ -29,20 +29,21 @@ static AvailableValsTy &getAvailableVals(void *AV) {
 }
 
 SSAUpdater::SSAUpdater(SmallVectorImpl<PHINode*> *NewPHI)
-  : AV(0), PrototypeValue(0), InsertedPHIs(NewPHI) {}
+  : AV(0), ProtoType(0), ProtoName(), InsertedPHIs(NewPHI) {}
 
 SSAUpdater::~SSAUpdater() {
   delete &getAvailableVals(AV);
 }
 
 /// Initialize - Reset this object to get ready for a new set of SSA
-/// updates.  ProtoValue is the value used to name PHI nodes.
-void SSAUpdater::Initialize(Value *ProtoValue) {
+/// updates with type 'Ty'.  PHI nodes get a name based on 'Name'.
+void SSAUpdater::Initialize(const Type *Ty, StringRef Name) {
   if (AV == 0)
     AV = new AvailableValsTy();
   else
     getAvailableVals(AV).clear();
-  PrototypeValue = ProtoValue;
+  ProtoType = Ty;
+  ProtoName = Name;
 }
 
 /// HasValueForBlock - Return true if the SSAUpdater already has a value for
@@ -54,8 +55,8 @@ bool SSAUpdater::HasValueForBlock(BasicBlock *BB) const {
 /// AddAvailableValue - Indicate that a rewritten value is available in the
 /// specified block with the specified value.
 void SSAUpdater::AddAvailableValue(BasicBlock *BB, Value *V) {
-  assert(PrototypeValue != 0 && "Need to initialize SSAUpdater");
-  assert(PrototypeValue->getType() == V->getType() &&
+  assert(ProtoType != 0 && "Need to initialize SSAUpdater");
+  assert(ProtoType == V->getType() &&
          "All rewritten values must have the same type");
   getAvailableVals(AV)[BB] = V;
 }
@@ -148,7 +149,7 @@ Value *SSAUpdater::GetValueInMiddleOfBlock(BasicBlock *BB) {
 
   // If there are no predecessors, just return undef.
   if (PredValues.empty())
-    return UndefValue::get(PrototypeValue->getType());
+    return UndefValue::get(ProtoType);
 
   // Otherwise, if all the merged values are the same, just use it.
   if (SingularValue != 0)
@@ -168,9 +169,7 @@ Value *SSAUpdater::GetValueInMiddleOfBlock(BasicBlock *BB) {
   }
 
   // Ok, we have no way out, insert a new one now.
-  PHINode *InsertedPHI = PHINode::Create(PrototypeValue->getType(),
-                                         PrototypeValue->getName(),
-                                         &BB->front());
+  PHINode *InsertedPHI = PHINode::Create(ProtoType, ProtoName, &BB->front());
   InsertedPHI->reserveOperandSpace(PredValues.size());
 
   // Fill in all the predecessors of the PHI.
@@ -282,15 +281,14 @@ public:
   /// GetUndefVal - Get an undefined value of the same type as the value
   /// being handled.
   static Value *GetUndefVal(BasicBlock *BB, SSAUpdater *Updater) {
-    return UndefValue::get(Updater->PrototypeValue->getType());
+    return UndefValue::get(Updater->ProtoType);
   }
 
   /// CreateEmptyPHI - Create a new PHI instruction in the specified block.
   /// Reserve space for the operands but do not fill them in yet.
   static Value *CreateEmptyPHI(BasicBlock *BB, unsigned NumPreds,
                                SSAUpdater *Updater) {
-    PHINode *PHI = PHINode::Create(Updater->PrototypeValue->getType(),
-                                   Updater->PrototypeValue->getName(),
+    PHINode *PHI = PHINode::Create(Updater->ProtoType, Updater->ProtoName,
                                    &BB->front());
     PHI->reserveOperandSpace(NumPreds);
     return PHI;