1 files changed, 34 insertions, 11 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 2771e0e1c19..91fdda45ac7 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -2166,7 +2166,7 @@ Instruction *InstCombiner::optimizeBitCastFromPhi(CastInst &CI, PHINode *PN) {
   SmallSetVector<PHINode *, 4> OldPhiNodes;
 
   // Find all of the A->B casts and PHI nodes.
-  // We need to inpect all related PHI nodes, but PHIs can be cyclic, so
+  // We need to inspect all related PHI nodes, but PHIs can be cyclic, so
   // OldPhiNodes is used to track all known PHI nodes, before adding a new
   // PHI to PhiWorklist, it is checked against and added to OldPhiNodes first.
   PhiWorklist.push_back(PN);
@@ -2241,20 +2241,43 @@ Instruction *InstCombiner::optimizeBitCastFromPhi(CastInst &CI, PHINode *PN) {
     }
   }
 
+  // Traverse all accumulated PHI nodes and process its users,
+  // which are Stores and BitcCasts. Without this processing
+  // NewPHI nodes could be replicated and could lead to extra
+  // moves generated after DeSSA.
   // If there is a store with type B, change it to type A.
-  for (User *U : PN->users()) {
-    auto *SI = dyn_cast<StoreInst>(U);
-    if (SI && SI->isSimple() && SI->getOperand(0) == PN) {
-      Builder.SetInsertPoint(SI);
-      auto *NewBC =
-          cast<BitCastInst>(Builder.CreateBitCast(NewPNodes[PN], SrcTy));
-      SI->setOperand(0, NewBC);
-      Worklist.Add(SI);
-      assert(hasStoreUsersOnly(*NewBC));
+
+
+  // Replace users of BitCast B->A with NewPHI. These will help
+  // later to get rid off a closure formed by OldPHI nodes.
+  Instruction *RetVal = nullptr;
+  for (auto *OldPN : OldPhiNodes) {
+    PHINode *NewPN = NewPNodes[OldPN];
+    for (User *V : OldPN->users()) {
+      if (auto *SI = dyn_cast<StoreInst>(V)) {
+        if (SI->isSimple() && SI->getOperand(0) == OldPN) {
+          Builder.SetInsertPoint(SI);
+          auto *NewBC =
+            cast<BitCastInst>(Builder.CreateBitCast(NewPN, SrcTy));
+          SI->setOperand(0, NewBC);
+          Worklist.Add(SI);
+          assert(hasStoreUsersOnly(*NewBC));
+        }
+      }
+      else if (auto *BCI = dyn_cast<BitCastInst>(V)) {
+        // Verify it's a B->A cast.
+        Type *TyB = BCI->getOperand(0)->getType();
+        Type *TyA = BCI->getType();
+        if (TyA == DestTy && TyB == SrcTy) {
+          Instruction *I = replaceInstUsesWith(*BCI, NewPN);
+          if (BCI == &CI)
+            RetVal = I;
+        }
+      }
     }
   }
 
-  return replaceInstUsesWith(CI, NewPNodes[PN]);
+  return RetVal;
 }
 
 Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {