From: Nirav Dave <niravd@google.com>
Date: Mon, 23 Jul 2018 16:43:42 +0000 (+0000)
Subject: [Legalize] Elide MERGE_VALUES created by scalarizeVectorLoad.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=eac6487bf2a30103b60b1b825563f251e0be6ce0;p=llvm

[Legalize] Elide MERGE_VALUES created by scalarizeVectorLoad.

scalarizeVectorLoad creates MERGE_VALUES nodes which are immediately
decomposed in expandLoad. Elide the node in these cases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@337708 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp b/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp
index ed88806ae8a..ee2906f9e82 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp
@@ -680,9 +680,14 @@ SDValue VectorLegalizer::ExpandLoad(SDValue Op) {
     Value = DAG.getBuildVector(Op.getNode()->getValueType(0), dl, Vals);
   } else {
     SDValue Scalarized = TLI.scalarizeVectorLoad(LD, DAG);
-
-    NewChain = Scalarized.getValue(1);
-    Value = Scalarized.getValue(0);
+    // Skip past MERGE_VALUE node if known.
+    if (Scalarized->getOpcode() == ISD::MERGE_VALUES) {
+      NewChain = Scalarized.getOperand(1);
+      Value = Scalarized.getOperand(0);
+    } else {
+      NewChain = Scalarized.getValue(1);
+      Value = Scalarized.getValue(0);
+    }
   }
 
   AddLegalizedOperand(Op.getValue(0), Value);
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 4c885f90363..75d0a6bd58e 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -3984,6 +3984,8 @@ TargetLowering::expandUnalignedLoad(LoadSDNode *LD, SelectionDAG &DAG) const {
       if (!isOperationLegalOrCustom(ISD::LOAD, intVT)) {
         // Scalarize the load and let the individual components be handled.
         SDValue Scalarized = scalarizeVectorLoad(LD, DAG);
+        if (Scalarized->getOpcode() == ISD::MERGE_VALUES)
+	  return std::make_pair(Scalarized.getOperand(0), Scalarized.getOperand(1));
         return std::make_pair(Scalarized.getValue(0), Scalarized.getValue(1));
       }