Reintroduce r135730, this is indeed the right approach, there is no

native 256-bit vector instruction to do scalar_to_vector.

llvm-svn: 136001

1 files changed, 18 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index d2c8778debd..0b5ac6a2519 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -983,6 +983,7 @@ X86TargetLowering::X86TargetLowering(X86TargetMachine &TM)
       setOperationAction(ISD::VECTOR_SHUFFLE,     SVT, Custom);
       setOperationAction(ISD::INSERT_VECTOR_ELT,  SVT, Custom);
       setOperationAction(ISD::EXTRACT_VECTOR_ELT, SVT, Custom);
+      setOperationAction(ISD::SCALAR_TO_VECTOR,   SVT, Custom);
       setOperationAction(ISD::INSERT_SUBVECTOR,   SVT, Custom);
     }
 
@@ -6324,9 +6325,26 @@ X86TargetLowering::LowerINSERT_VECTOR_ELT(SDValue Op, SelectionDAG &DAG) const {
 
 SDValue
 X86TargetLowering::LowerSCALAR_TO_VECTOR(SDValue Op, SelectionDAG &DAG) const {
+  LLVMContext *Context = DAG.getContext();
   DebugLoc dl = Op.getDebugLoc();
   EVT OpVT = Op.getValueType();
 
+  // If this is a 256-bit vector result, first insert into a 128-bit
+  // vector and then insert into the 256-bit vector.
+  if (OpVT.getSizeInBits() > 128) {
+    // Insert into a 128-bit vector.
+    EVT VT128 = EVT::getVectorVT(*Context,
+                                 OpVT.getVectorElementType(),
+                                 OpVT.getVectorNumElements() / 2);
+
+    Op = DAG.getNode(ISD::SCALAR_TO_VECTOR, dl, VT128, Op.getOperand(0));
+
+    // Insert the 128-bit vector.
+    return Insert128BitVector(DAG.getNode(ISD::UNDEF, dl, OpVT), Op,
+                              DAG.getConstant(0, MVT::i32),
+                              DAG, dl);
+  }
+
   if (Op.getValueType() == MVT::v1i64 &&
       Op.getOperand(0).getValueType() == MVT::i64)
     return DAG.getNode(ISD::SCALAR_TO_VECTOR, dl, MVT::v1i64, Op.getOperand(0));