1 files changed, 74 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 98206b7..adfb960 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -12114,3 +12114,77 @@ SDValue TargetLowering::expandVectorNaryOpBySplitting(SDNode *Node,
   SDValue SplitOpHi = DAG.getNode(Opcode, DL, HiVT, HiOps);
   return DAG.getNode(ISD::CONCAT_VECTORS, DL, VT, SplitOpLo, SplitOpHi);
 }
+
+SDValue TargetLowering::scalarizeExtractedVectorLoad(EVT ResultVT,
+                                                     const SDLoc &DL,
+                                                     EVT InVecVT, SDValue EltNo,
+                                                     LoadSDNode *OriginalLoad,
+                                                     SelectionDAG &DAG) const {
+  assert(OriginalLoad->isSimple());
+
+  EVT VecEltVT = InVecVT.getVectorElementType();
+
+  // If the vector element type is not a multiple of a byte then we are unable
+  // to correctly compute an address to load only the extracted element as a
+  // scalar.
+  if (!VecEltVT.isByteSized())
+    return SDValue();
+
+  ISD::LoadExtType ExtTy =
+      ResultVT.bitsGT(VecEltVT) ? ISD::EXTLOAD : ISD::NON_EXTLOAD;
+  if (!isOperationLegalOrCustom(ISD::LOAD, VecEltVT) ||
+      !shouldReduceLoadWidth(OriginalLoad, ExtTy, VecEltVT))
+    return SDValue();
+
+  Align Alignment = OriginalLoad->getAlign();
+  MachinePointerInfo MPI;
+  if (auto *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo)) {
+    int Elt = ConstEltNo->getZExtValue();
+    unsigned PtrOff = VecEltVT.getSizeInBits() * Elt / 8;
+    MPI = OriginalLoad->getPointerInfo().getWithOffset(PtrOff);
+    Alignment = commonAlignment(Alignment, PtrOff);
+  } else {
+    // Discard the pointer info except the address space because the memory
+    // operand can't represent this new access since the offset is variable.
+    MPI = MachinePointerInfo(OriginalLoad->getPointerInfo().getAddrSpace());
+    Alignment = commonAlignment(Alignment, VecEltVT.getSizeInBits() / 8);
+  }
+
+  unsigned IsFast = 0;
+  if (!allowsMemoryAccess(*DAG.getContext(), DAG.getDataLayout(), VecEltVT,
+                          OriginalLoad->getAddressSpace(), Alignment,
+                          OriginalLoad->getMemOperand()->getFlags(), &IsFast) ||
+      !IsFast)
+    return SDValue();
+
+  SDValue NewPtr =
+      getVectorElementPointer(DAG, OriginalLoad->getBasePtr(), InVecVT, EltNo);
+
+  // We are replacing a vector load with a scalar load. The new load must have
+  // identical memory op ordering to the original.
+  SDValue Load;
+  if (ResultVT.bitsGT(VecEltVT)) {
+    // If the result type of vextract is wider than the load, then issue an
+    // extending load instead.
+    ISD::LoadExtType ExtType = isLoadExtLegal(ISD::ZEXTLOAD, ResultVT, VecEltVT)
+                                   ? ISD::ZEXTLOAD
+                                   : ISD::EXTLOAD;
+    Load = DAG.getExtLoad(ExtType, DL, ResultVT, OriginalLoad->getChain(),
+                          NewPtr, MPI, VecEltVT, Alignment,
+                          OriginalLoad->getMemOperand()->getFlags(),
+                          OriginalLoad->getAAInfo());
+    DAG.makeEquivalentMemoryOrdering(OriginalLoad, Load);
+  } else {
+    // The result type is narrower or the same width as the vector element
+    Load = DAG.getLoad(VecEltVT, DL, OriginalLoad->getChain(), NewPtr, MPI,
+                       Alignment, OriginalLoad->getMemOperand()->getFlags(),
+                       OriginalLoad->getAAInfo());
+    DAG.makeEquivalentMemoryOrdering(OriginalLoad, Load);
+    if (ResultVT.bitsLT(VecEltVT))
+      Load = DAG.getNode(ISD::TRUNCATE, DL, ResultVT, Load);
+    else
+      Load = DAG.getBitcast(ResultVT, Load);
+  }
+
+  return Load;
+}