[DAG] 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.

llvm-svn: 305468

1 files changed, 21 insertions, 10 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index b5e1b492e96..3a9c17045c1 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -12874,9 +12874,6 @@ bool DAGCombiner::MergeConsecutiveStores(StoreSDNode *St) {
       if (Ld->isVolatile() || Ld->isIndexed())
         break;
 
-      // We do not accept ext loads.
-      if (Ld->getExtensionType() != ISD::NON_EXTLOAD)
-        break;
 
       // The stored memory type must be the same.
       if (Ld->getMemoryVT() != MemVT)
@@ -13014,17 +13011,31 @@ 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 (TLI.isTypeLegal(JointMemOpVT)) {
+      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) {