Allow truncated and extend memory operations in Store Merge. NFCI.

As all store merges checks are based on the memory operation
performed, allow use of truncated stores and extended loads as valid
input candidates for merging.

Relanding after fixing selection between truncated and normal store.

llvm-svn: 305701

1 files changed, 46 insertions, 24 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index a7b411cecac..c2306a16d40 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -469,7 +469,8 @@ namespace {
     /// \return True if a merged store was created.
     bool MergeStoresOfConstantsOrVecElts(SmallVectorImpl<MemOpLink> &StoreNodes,
                                          EVT MemVT, unsigned NumStores,
-                                         bool IsConstantSrc, bool UseVector);
+                                         bool IsConstantSrc, bool UseVector,
+                                         bool UseTrunc);
 
     /// This is a helper function for MergeConsecutiveStores.
     /// Stores that may be merged are placed in StoreNodes.
@@ -12378,8 +12379,8 @@ SDValue DAGCombiner::getMergeStoreChains(SmallVectorImpl<MemOpLink> &StoreNodes,
 }
 
 bool DAGCombiner::MergeStoresOfConstantsOrVecElts(
-                  SmallVectorImpl<MemOpLink> &StoreNodes, EVT MemVT,
-                  unsigned NumStores, bool IsConstantSrc, bool UseVector) {
+    SmallVectorImpl<MemOpLink> &StoreNodes, EVT MemVT, unsigned NumStores,
+    bool IsConstantSrc, bool UseVector, bool UseTrunc) {
   // Make sure we have something to merge.
   if (NumStores < 2)
     return false;
@@ -12464,7 +12465,7 @@ bool DAGCombiner::MergeStoresOfConstantsOrVecElts(
 
   // make sure we use trunc store if it's necessary to be legal.
   SDValue NewStore;
-  if (TLI.isTypeLegal(StoredVal.getValueType())) {
+  if (UseVector || !UseTrunc) {
     NewStore = DAG.getStore(NewChain, DL, StoredVal, FirstInChain->getBasePtr(),
                             FirstInChain->getPointerInfo(),
                             FirstInChain->getAlignment());
@@ -12721,8 +12722,9 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
       LSBaseSDNode *FirstInChain = StoreNodes[0].MemNode;
       unsigned FirstStoreAS = FirstInChain->getAddressSpace();
       unsigned FirstStoreAlign = FirstInChain->getAlignment();
-      unsigned LastLegalType = 0;
-      unsigned LastLegalVectorType = 0;
+      unsigned LastLegalType = 1;
+      unsigned LastLegalVectorType = 1;
+      bool LastIntegerTrunc = false;
       bool NonZero = false;
       for (unsigned i = 0; i < NumConsecutiveStores; ++i) {
         StoreSDNode *ST = cast<StoreSDNode>(StoreNodes[i].MemNode);
@@ -12747,6 +12749,7 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
             TLI.allowsMemoryAccess(Context, DL, StoreTy, FirstStoreAS,
                                    FirstStoreAlign, &IsFast) &&
             IsFast) {
+          LastIntegerTrunc = false;
           LastLegalType = i + 1;
           // Or check whether a truncstore is legal.
         } else if (TLI.getTypeAction(Context, StoreTy) ==
@@ -12758,6 +12761,7 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
               TLI.allowsMemoryAccess(Context, DL, LegalizedStoredValueTy,
                                      FirstStoreAS, FirstStoreAlign, &IsFast) &&
               IsFast) {
+            LastIntegerTrunc = true;
             LastLegalType = i + 1;
           }
         }
@@ -12787,8 +12791,8 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
       bool UseVector = (LastLegalVectorType > LastLegalType) && !NoVectors;
       unsigned NumElem = (UseVector) ? LastLegalVectorType : LastLegalType;
 
-      bool Merged = MergeStoresOfConstantsOrVecElts(StoreNodes, MemVT, NumElem,
-                                                    true, UseVector);
+      bool Merged = MergeStoresOfConstantsOrVecElts(
+          StoreNodes, MemVT, NumElem, true, UseVector, LastIntegerTrunc);
       if (!Merged) {
         StoreNodes.erase(StoreNodes.begin(), StoreNodes.begin() + NumElem);
         continue;
@@ -12836,7 +12840,7 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
       }
 
       bool Merged = MergeStoresOfConstantsOrVecElts(
-          StoreNodes, MemVT, NumStoresToMerge, false, true);
+          StoreNodes, MemVT, NumStoresToMerge, false, true, false);
       if (!Merged) {
         StoreNodes.erase(StoreNodes.begin(),
                          StoreNodes.begin() + NumStoresToMerge);
@@ -12919,10 +12923,11 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
     // Scan the memory operations on the chain and find the first
     // non-consecutive load memory address. These variables hold the index in
     // the store node array.
-    unsigned LastConsecutiveLoad = 0;
+    unsigned LastConsecutiveLoad = 1;
     // This variable refers to the size and not index in the array.
-    unsigned LastLegalVectorType = 0;
-    unsigned LastLegalIntegerType = 0;
+    unsigned LastLegalVectorType = 1;
+    unsigned LastLegalIntegerType = 1;
+    bool DoIntegerTruncate = false;
     StartAddress = LoadNodes[0].OffsetFromBase;
     SDValue FirstChain = FirstLoad->getChain();
     for (unsigned i = 1; i < LoadNodes.size(); ++i) {
@@ -12958,11 +12963,12 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
           IsFastSt &&
           TLI.allowsMemoryAccess(Context, DL, StoreTy, FirstLoadAS,
                                  FirstLoadAlign, &IsFastLd) &&
-          IsFastLd)
+          IsFastLd) {
         LastLegalIntegerType = i + 1;
-      // Or check whether a truncstore and extload is legal.
-      else if (TLI.getTypeAction(Context, StoreTy) ==
-               TargetLowering::TypePromoteInteger) {
+        DoIntegerTruncate = false;
+        // Or check whether a truncstore and extload is legal.
+      } else if (TLI.getTypeAction(Context, StoreTy) ==
+                 TargetLowering::TypePromoteInteger) {
         EVT LegalizedStoredValueTy = TLI.getTypeToTransformTo(Context, StoreTy);
         if (TLI.isTruncStoreLegal(LegalizedStoredValueTy, StoreTy) &&
             TLI.canMergeStoresTo(FirstStoreAS, LegalizedStoredValueTy) &&
@@ -12976,8 +12982,10 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
             IsFastSt &&
             TLI.allowsMemoryAccess(Context, DL, StoreTy, FirstLoadAS,
                                    FirstLoadAlign, &IsFastLd) &&
-            IsFastLd)
+            IsFastLd) {
           LastLegalIntegerType = i + 1;
+          DoIntegerTruncate = true;
+        }
       }
     }
 
@@ -13012,17 +13020,31 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
 
     // The merged loads are required to have the same incoming chain, so
     // using the first's chain is acceptable.
-    SDValue NewLoad = DAG.getLoad(JointMemOpVT, LoadDL, FirstLoad->getChain(),
-                                  FirstLoad->getBasePtr(),
-                                  FirstLoad->getPointerInfo(), FirstLoadAlign);
 
     SDValue NewStoreChain = getMergeStoreChains(StoreNodes, NumElem);
-
     AddToWorklist(NewStoreChain.getNode());
 
-    SDValue NewStore = DAG.getStore(
-        NewStoreChain, StoreDL, NewLoad, FirstInChain->getBasePtr(),
-        FirstInChain->getPointerInfo(), FirstStoreAlign);
+    SDValue NewLoad, NewStore;
+    if (UseVectorTy || !DoIntegerTruncate) {
+      NewLoad = DAG.getLoad(JointMemOpVT, LoadDL, FirstLoad->getChain(),
+                            FirstLoad->getBasePtr(),
+                            FirstLoad->getPointerInfo(), FirstLoadAlign);
+      NewStore = DAG.getStore(NewStoreChain, StoreDL, NewLoad,
+                              FirstInChain->getBasePtr(),
+                              FirstInChain->getPointerInfo(), FirstStoreAlign);
+    } else { // This must be the truncstore/extload case
+      EVT ExtendedTy =
+          TLI.getTypeToTransformTo(*DAG.getContext(), JointMemOpVT);
+      NewLoad =
+          DAG.getExtLoad(ISD::EXTLOAD, LoadDL, ExtendedTy, FirstLoad->getChain(),
+                         FirstLoad->getBasePtr(), FirstLoad->getPointerInfo(),
+                         JointMemOpVT, FirstLoadAlign);
+      NewStore = DAG.getTruncStore(NewStoreChain, StoreDL, NewLoad,
+                                   FirstInChain->getBasePtr(),
+                                   FirstInChain->getPointerInfo(), JointMemOpVT,
+                                   FirstInChain->getAlignment(),
+                                   FirstInChain->getMemOperand()->getFlags());
+    }
 
     // Transfer chain users from old loads to the new load.
     for (unsigned i = 0; i < NumElem; ++i) {