1 files changed, 35 insertions, 15 deletions

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index d5d3f7a61a9f..432c86dd6f1e 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1118,22 +1118,30 @@ SDValue DAGCombiner::PromoteIntBinOp(SDValue Op) {
     SDValue RV =
         DAG.getNode(ISD::TRUNCATE, DL, VT, DAG.getNode(Opc, DL, PVT, NN0, NN1));
 
-    // New replace instances of N0 and N1
-    if (Replace0 && N0 && N0.getOpcode() != ISD::DELETED_NODE && NN0 &&
-        NN0.getOpcode() != ISD::DELETED_NODE) {
+    // We are always replacing N0/N1's use in N and only need
+    // additional replacements if there are additional uses.
+    Replace0 &= !N0->hasOneUse();
+    Replace1 &= (N0 != N1) && !N1->hasOneUse();
+
+    // Combine Op here so it is presreved past replacements.
+    CombineTo(Op.getNode(), RV);
+
+    // If operands have a use ordering, make sur we deal with
+    // predecessor first.
+    if (Replace0 && Replace1 && N0.getNode()->isPredecessorOf(N1.getNode())) {
+      std::swap(N0, N1);
+      std::swap(NN0, NN1);
+    }
+
+    if (Replace0) {
       AddToWorklist(NN0.getNode());
       ReplaceLoadWithPromotedLoad(N0.getNode(), NN0.getNode());
     }
-
-    if (Replace1 && N1 && N1.getOpcode() != ISD::DELETED_NODE && NN1 &&
-        NN1.getOpcode() != ISD::DELETED_NODE) {
+    if (Replace1) {
       AddToWorklist(NN1.getNode());
       ReplaceLoadWithPromotedLoad(N1.getNode(), NN1.getNode());
     }
-
-    // Deal with Op being deleted.
-    if (Op && Op.getOpcode() != ISD::DELETED_NODE)
-      return RV;
+    return Op;
   }
   return SDValue();
 }
@@ -12599,25 +12607,37 @@ void DAGCombiner::getStoreMergeCandidates(
         }
 }
 
-// We need to check that merging these stores does not cause a loop
-// in the DAG. Any store candidate may depend on another candidate
+// We need to check that merging these stores does not cause a loop in
+// the DAG. Any store candidate may depend on another candidate
 // indirectly through its operand (we already consider dependencies
 // through the chain). Check in parallel by searching up from
 // non-chain operands of candidates.
+
 bool DAGCombiner::checkMergeStoreCandidatesForDependencies(
     SmallVectorImpl<MemOpLink> &StoreNodes, unsigned NumStores) {
+
+  // FIXME: We should be able to truncate a full search of
+  // predecessors by doing a BFS and keeping tabs the originating
+  // stores from which worklist nodes come from in a similar way to
+  // TokenFactor simplfication.
+
   SmallPtrSet<const SDNode *, 16> Visited;
   SmallVector<const SDNode *, 8> Worklist;
-  // search ops of store candidates
+  unsigned int Max = 8192;
+  // Search Ops of store candidates.
   for (unsigned i = 0; i < NumStores; ++i) {
     SDNode *n = StoreNodes[i].MemNode;
     // Potential loops may happen only through non-chain operands
     for (unsigned j = 1; j < n->getNumOperands(); ++j)
       Worklist.push_back(n->getOperand(j).getNode());
   }
-  // search through DAG. We can stop early if we find a storenode
+  // Search through DAG. We can stop early if we find a store node.
   for (unsigned i = 0; i < NumStores; ++i) {
-    if (SDNode::hasPredecessorHelper(StoreNodes[i].MemNode, Visited, Worklist))
+    if (SDNode::hasPredecessorHelper(StoreNodes[i].MemNode, Visited, Worklist,
+                                     Max))
+      return false;
+    // Check if we ended early, failing conservatively if so.
+    if (Visited.size() >= Max)
       return false;
   }
   return true;