From 83defd1902545f6e44b64d59931f6c4e7a905250 Mon Sep 17 00:00:00 2001
From: Nirav Dave <niravd@google.com>
Date: Tue, 11 Apr 2017 13:41:17 +0000
Subject: [PATCH] [SDAG] Factor ChainMerge into helper function NFCI.

llvm-svn: 299938
---
 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 47 +++++++++++++++------------
 1 file changed, 27 insertions(+), 20 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 8cb899f..9e4d6fe 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -451,6 +451,11 @@ namespace {
                           EVT LoadResultTy, EVT &ExtVT, EVT &LoadedVT,
                           bool &NarrowLoad);
 
+    /// Helper function for MergeConsecutiveStores which merges the
+    /// component store chains.
+    SDValue getMergeStoreChains(SmallVectorImpl<MemOpLink> &StoreNodes,
+                                unsigned NumStores);
+
     /// This is a helper function for MergeConsecutiveStores. When the source
     /// elements of the consecutive stores are all constants or all extracted
     /// vector elements, try to merge them into one larger store.
@@ -12094,6 +12099,26 @@ bool DAGCombiner::isMulAddWithConstProfitable(SDNode *MulNode,
   return false;
 }
 
+SDValue DAGCombiner::getMergeStoreChains(SmallVectorImpl<MemOpLink> &StoreNodes,
+                                         unsigned NumStores) {
+  SmallVector<SDValue, 8> Chains;
+  SmallPtrSet<const SDNode *, 8> Visited;
+  SDLoc StoreDL(StoreNodes[0].MemNode);
+
+  for (unsigned i = 0; i < NumStores; ++i) {
+    Visited.insert(StoreNodes[i].MemNode);
+  }
+
+  // don't include nodes that are children
+  for (unsigned i = 0; i < NumStores; ++i) {
+    if (Visited.count(StoreNodes[i].MemNode->getChain().getNode()) == 0)
+      Chains.push_back(StoreNodes[i].MemNode->getChain());
+  }
+
+  assert(Chains.size() > 0 && "Chain should have generated a chain");
+  return DAG.getNode(ISD::TokenFactor, StoreDL, MVT::Other, Chains);
+}
+
 bool DAGCombiner::MergeStoresOfConstantsOrVecElts(
                   SmallVectorImpl<MemOpLink> &StoreNodes, EVT MemVT,
                   unsigned NumStores, bool IsConstantSrc, bool UseVector) {
@@ -12176,17 +12201,8 @@ bool DAGCombiner::MergeStoresOfConstantsOrVecElts(
     StoredVal = DAG.getConstant(StoreInt, DL, StoreTy);
   }
 
-  SmallVector<SDValue, 8> Chains;
-
-  // Gather all Chains we're inheriting. As generally all chains are
-  // equal, do minor check to remove obvious redundancies.
-  Chains.push_back(StoreNodes[0].MemNode->getChain());
-  for (unsigned i = 1; i < NumStores; ++i)
-    if (StoreNodes[0].MemNode->getChain() != StoreNodes[i].MemNode->getChain())
-      Chains.push_back(StoreNodes[i].MemNode->getChain());
-
   LSBaseSDNode *FirstInChain = StoreNodes[0].MemNode;
-  SDValue NewChain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, Chains);
+  SDValue NewChain = getMergeStoreChains(StoreNodes, NumStores);
   SDValue NewStore = DAG.getStore(NewChain, DL, StoredVal,
                                   FirstInChain->getBasePtr(),
                                   FirstInChain->getPointerInfo(),
@@ -12635,14 +12651,6 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
   if (NumElem < 2)
     return false;
 
-  // Collect the chains from all merged stores. Because the common case
-  // all chains are the same, check if we match the first Chain.
-  SmallVector<SDValue, 8> MergeStoreChains;
-  MergeStoreChains.push_back(StoreNodes[0].MemNode->getChain());
-  for (unsigned i = 1; i < NumElem; ++i)
-    if (StoreNodes[0].MemNode->getChain() != StoreNodes[i].MemNode->getChain())
-      MergeStoreChains.push_back(StoreNodes[i].MemNode->getChain());
-
   // Find if it is better to use vectors or integers to load and store
   // to memory.
   EVT JointMemOpVT;
@@ -12662,8 +12670,7 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
                                 FirstLoad->getBasePtr(),
                                 FirstLoad->getPointerInfo(), FirstLoadAlign);
 
-  SDValue NewStoreChain =
-    DAG.getNode(ISD::TokenFactor, StoreDL, MVT::Other, MergeStoreChains);
+  SDValue NewStoreChain = getMergeStoreChains(StoreNodes, NumElem);
 
   AddToWorklist(NewStoreChain.getNode());
 
-- 
2.7.4