1 files changed, 20 insertions, 13 deletions

diff --git a/lib/Transforms/ObjCARC/ObjCARCOpts.cpp b/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
index 21e2848030fc..9a02174556fc 100644
--- a/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
+++ b/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
@@ -600,6 +600,17 @@ ObjCARCOpt::OptimizeRetainRVCall(Function &F, Instruction *RetainRV) {
     }
   }
 
+  // Track PHIs which are equivalent to our Arg.
+  SmallDenseSet<const Value*, 2> EquivalentArgs;
+  EquivalentArgs.insert(Arg);
+
+  // Add PHIs that are equivalent to Arg to ArgUsers.
+  if (const PHINode *PN = dyn_cast<PHINode>(Arg)) {
+    SmallVector<const Value *, 2> ArgUsers;
+    getEquivalentPHIs(*PN, ArgUsers);
+    EquivalentArgs.insert(ArgUsers.begin(), ArgUsers.end());
+  }
+
   // Check for being preceded by an objc_autoreleaseReturnValue on the same
   // pointer. In this case, we can delete the pair.
   BasicBlock::iterator I = RetainRV->getIterator(),
@@ -609,7 +620,7 @@ ObjCARCOpt::OptimizeRetainRVCall(Function &F, Instruction *RetainRV) {
       --I;
     while (I != Begin && IsNoopInstruction(&*I));
     if (GetBasicARCInstKind(&*I) == ARCInstKind::AutoreleaseRV &&
-        GetArgRCIdentityRoot(&*I) == Arg) {
+        EquivalentArgs.count(GetArgRCIdentityRoot(&*I))) {
       Changed = true;
       ++NumPeeps;
 
@@ -914,8 +925,8 @@ void ObjCARCOpt::OptimizeIndividualCalls(Function &F) {
           GetRCIdentityRoot(PN->getIncomingValue(i));
         if (IsNullOrUndef(Incoming))
           HasNull = true;
-        else if (cast<TerminatorInst>(PN->getIncomingBlock(i)->back())
-                   .getNumSuccessors() != 1) {
+        else if (PN->getIncomingBlock(i)->getTerminator()->getNumSuccessors() !=
+                 1) {
           HasCriticalEdges = true;
           break;
         }
@@ -1084,18 +1095,15 @@ ObjCARCOpt::CheckForCFGHazards(const BasicBlock *BB,
            "Unknown top down sequence state.");
 
     const Value *Arg = I->first;
-    const TerminatorInst *TI = cast<TerminatorInst>(&BB->back());
     bool SomeSuccHasSame = false;
     bool AllSuccsHaveSame = true;
     bool NotAllSeqEqualButKnownSafe = false;
 
-    succ_const_iterator SI(TI), SE(TI, false);
-
-    for (; SI != SE; ++SI) {
+    for (const BasicBlock *Succ : successors(BB)) {
       // If VisitBottomUp has pointer information for this successor, take
       // what we know about it.
       const DenseMap<const BasicBlock *, BBState>::iterator BBI =
-        BBStates.find(*SI);
+          BBStates.find(Succ);
       assert(BBI != BBStates.end());
       const BottomUpPtrState &SuccS = BBI->second.getPtrBottomUpState(Arg);
       const Sequence SuccSSeq = SuccS.GetSeq();
@@ -1414,21 +1422,20 @@ ComputePostOrders(Function &F,
   BasicBlock *EntryBB = &F.getEntryBlock();
   BBState &MyStates = BBStates[EntryBB];
   MyStates.SetAsEntry();
-  TerminatorInst *EntryTI = cast<TerminatorInst>(&EntryBB->back());
+  Instruction *EntryTI = EntryBB->getTerminator();
   SuccStack.push_back(std::make_pair(EntryBB, succ_iterator(EntryTI)));
   Visited.insert(EntryBB);
   OnStack.insert(EntryBB);
   do {
   dfs_next_succ:
     BasicBlock *CurrBB = SuccStack.back().first;
-    TerminatorInst *TI = cast<TerminatorInst>(&CurrBB->back());
-    succ_iterator SE(TI, false);
+    succ_iterator SE(CurrBB->getTerminator(), false);
 
     while (SuccStack.back().second != SE) {
       BasicBlock *SuccBB = *SuccStack.back().second++;
       if (Visited.insert(SuccBB).second) {
-        TerminatorInst *TI = cast<TerminatorInst>(&SuccBB->back());
-        SuccStack.push_back(std::make_pair(SuccBB, succ_iterator(TI)));
+        SuccStack.push_back(
+            std::make_pair(SuccBB, succ_iterator(SuccBB->getTerminator())));
         BBStates[CurrBB].addSucc(SuccBB);
         BBState &SuccStates = BBStates[SuccBB];
         SuccStates.addPred(CurrBB);