3 files changed, 45 insertions, 22 deletions

diff --git a/include/llvm/CodeGen/SelectionDAG.h b/include/llvm/CodeGen/SelectionDAG.h
index 4b3f904bc6..82becca315 100644
--- a/include/llvm/CodeGen/SelectionDAG.h
+++ b/include/llvm/CodeGen/SelectionDAG.h
@@ -1149,7 +1149,8 @@ public:
 
   /// SplitVectorOperand - Split the node's operand with EXTRACT_SUBVECTOR and
   /// return the low/high part.
-  std::pair<SDValue, SDValue> SplitVectorOperand(SDNode *N, unsigned OpNo) {
+  std::pair<SDValue, SDValue> SplitVectorOperand(const SDNode *N, unsigned OpNo)
+  {
     return SplitVector(N->getOperand(OpNo), SDLoc(N));
   }
 
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 15b4ddc033..20b0981e97 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -4327,6 +4327,23 @@ SDValue DAGCombiner::visitSELECT(SDNode *N) {
   return SDValue();
 }
 
+static
+std::pair<SDValue, SDValue> SplitVSETCC(const SDNode *N, SelectionDAG &DAG) {
+  SDLoc DL(N);
+  EVT LoVT, HiVT;
+  llvm::tie(LoVT, HiVT) = DAG.GetSplitDestVTs(N->getValueType(0));
+
+  // Split the inputs.
+  SDValue Lo, Hi, LL, LH, RL, RH;
+  llvm::tie(LL, LH) = DAG.SplitVectorOperand(N, 0);
+  llvm::tie(RL, RH) = DAG.SplitVectorOperand(N, 1);
+
+  Lo = DAG.getNode(N->getOpcode(), DL, LoVT, LL, RL, N->getOperand(2));
+  Hi = DAG.getNode(N->getOpcode(), DL, HiVT, LH, RH, N->getOperand(2));
+
+  return std::make_pair(Lo, Hi);
+}
+
 SDValue DAGCombiner::visitVSELECT(SDNode *N) {
   SDValue N0 = N->getOperand(0);
   SDValue N1 = N->getOperand(1);
@@ -4364,27 +4381,32 @@ SDValue DAGCombiner::visitVSELECT(SDNode *N) {
     }
   }
 
-  // Treat SETCC as a vector mask and promote the result type based on the
-  // targets expected SETCC result type. This will ensure that SETCC and VSELECT
-  // are both split by the type legalizer. This is done to prevent the type
-  // legalizer from unrolling SETCC into scalar comparions.
-  EVT SelectVT = N->getValueType(0);
-  EVT MaskVT = getSetCCResultType(SelectVT);
-  assert(MaskVT.isVector() && "Expected a vector type.");
-  if (N0.getOpcode() == ISD::SETCC && N0.getValueType() != MaskVT) {
-    SDLoc MaskDL(N0);
+  // If the VSELECT result requires splitting and the mask is provided by a
+  // SETCC, then split both nodes and its operands before legalization. This
+  // prevents the type legalizer from unrolling SETCC into scalar comparisons
+  // and enables future optimizations (e.g. min/max pattern matching on X86).
+  if (N0.getOpcode() == ISD::SETCC) {
+    EVT VT = N->getValueType(0);
+
+    // Check if any splitting is required.
+    if (TLI.getTypeAction(*DAG.getContext(), VT) !=
+        TargetLowering::TypeSplitVector)
+      return SDValue();
 
-    // Extend the mask to the desired value type.
-    ISD::NodeType ExtendCode =
-      TargetLowering::getExtendForContent(TLI.getBooleanContents(true));
-    SDValue Mask = DAG.getNode(ExtendCode, MaskDL, MaskVT, N0);
+    SDValue Lo, Hi, CCLo, CCHi, LL, LH, RL, RH;
+    llvm::tie(CCLo, CCHi) = SplitVSETCC(N0.getNode(), DAG);
+    llvm::tie(LL, LH) = DAG.SplitVectorOperand(N, 1);
+    llvm::tie(RL, RH) = DAG.SplitVectorOperand(N, 2);
 
-    AddToWorkList(Mask.getNode());
+    Lo = DAG.getNode(N->getOpcode(), DL, LL.getValueType(), CCLo, LL, RL);
+    Hi = DAG.getNode(N->getOpcode(), DL, LH.getValueType(), CCHi, LH, RH);
 
-    SDValue LHS = N->getOperand(1);
-    SDValue RHS = N->getOperand(2);
+    // Add the new VSELECT nodes to the work list in case they need to be split
+    // again.
+    AddToWorkList(Lo.getNode());
+    AddToWorkList(Hi.getNode());
 
-    return DAG.getNode(ISD::VSELECT, DL, SelectVT, Mask, LHS, RHS);
+    return DAG.getNode(ISD::CONCAT_VECTORS, DL, VT, Lo, Hi);
   }
 
   return SDValue();
diff --git a/lib/CodeGen/SelectionDAG/LegalizeTypesGeneric.cpp b/lib/CodeGen/SelectionDAG/LegalizeTypesGeneric.cpp
index 9e97c49ddf..b3174fd373 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeTypesGeneric.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeTypesGeneric.cpp
@@ -488,11 +488,11 @@ void DAGTypeLegalizer::SplitRes_SELECT(SDNode *N, SDValue &Lo,
   SDValue Cond = N->getOperand(0);
   CL = CH = Cond;
   if (Cond.getValueType().isVector()) {
-    if (Cond.getOpcode() == ISD::SETCC) {
-      assert(Cond.getValueType() == getSetCCResultType(N->getValueType(0)) &&
-             "Condition has not been prepared for split!");
+    // Check if there are already splitted versions of the vector available and
+    // use those instead of splitting the mask operand again.
+    if (getTypeAction(Cond.getValueType()) == TargetLowering::TypeSplitVector)
       GetSplitVector(Cond, CL, CH);
-    } else
+    else
       llvm::tie(CL, CH) = DAG.SplitVector(Cond, dl);
   }