[SDAG] Remove the reliance on MI's allocation strategy for `MachineMemOperand` pointers attached to `MachineSDNodes` and instead have the `SelectionDAG` fully manage the memory for this array.

[chandlerc]

Summary

Prior to this change, the memory management was deeply confusing here --
The way the MI was built relied on the SelectionDAG allocating memory
for these arrays of pointers using the MachineFunction's allocator so
that the raw pointer to the array could be blindly copied into an
eventual MachineInstr. This creates a hard coupling between how
MachineInstrs allocate their array of MachineMemOperand pointers and
how the MachineSDNode does.

This change is motivated in large part by a change I am making to how
MachineFunction allocates these pointers, but it seems like a layering
improvement as well.

This would run the risk of increasing allocations overall, but I've
implemented an optimization that should avoid that by storing a single
MachineMemOperand pointer directly instead of allocating anything.
This is expected to be a net win because the vast majority of uses of
these only need a single pointer.

As a side-effect, this makes the API for updating a MachineSDNode and
a MachineInstr reasonably different which seems nice to avoid
unexpected coupling of these two layers. We can map between them, but we
shouldn't be *surprised* at where that occurs. =]

[chandlerc]

Doh, this doesn't have the change to do the clever optimization mentioned in the change description. I'll update it with that momentarily. But that will be just a tiny implementation detail, so probably fin eto start reviewing.

[chandlerc]

Update to include the optimization where we store a single MMO inline to avoid
allocation. Almost nothing changed, all tests continue to pass.

[hfinkel]

This code certainly looks cleaner.

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

7099

Use std::copy?

[chandlerc]

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

7099

Yep, made exactly this change when getting the right implementation here for the optimized form.

[hfinkel]

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

2256

Should we use TinyPtrVector here instead of making this PointerUnion and keeping NumMemRefs below?

[chandlerc]

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

2256

We can't. I tried so hard to do this. It was terrible.

In a word, MorphNodeTo.

We don't actually run constructors or destructors reliably for any SDNode subclasses. We allocate enough memory and with enough alignment for any of the subclasses, and then we just "switch" the subclass by writing to NodeType. Yay.

We have manual code in MorphNodeTo to "clean up" and "initialize" the members as needed.

I tried fixing this, and it is terrible. Nothing works.

We essentially *have* to allocate any extra storage off the DAG's allocator so it gets freed for us, and we have to use POD-ish data types here that we can update with a simple store regardless of what uninitialized garbage memory is left there due to MorphNodeTo.

Sorry I couldn't find anything less awful than this.

[hfinkel]

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

2256

Makes sense. Can you please add this as a comment?

Otherwise, I'm happy with this patch.

[bogner]

LGTM as long as Hal's good with your explanation of why we can't use TinyPtrVector.

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

2258–2262

Yep, sizeof(MachineSDNode) is 96 bytes either way (it's exactly 96 before this change, and 92 + 4 bytes padding after). I don't know if we need quite this long of a comment explaining that it's fine, but I guess it doesn't hurt.

2270

Should the doxygen of MachineSDNode mention SelectionDAG::setNodeMemRefs somewhere?

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

7112

C++ style casts are arguably a bit clearer (but feel free to ignore this if you disagree)

[chandlerc]

Address review feedback.

[chandlerc]

I think all done.

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

2270

Added comments explaining this.

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

7112

For primitive types, it never seems worth it to me, but I don't feel strongly here. Changed.

[rnk]

+1

llvm/lib/Target/X86/X86InstrInfo.cpp

5521–5522

There is only one other call site of extractLoadMemRefs, and its only called from X86InstrInfo.cpp. Can you migrate the other call site over to your extractLoadMMOs helper and delete MachineFunction::extractLoadMemRefs? Now that we can get an ArrayRef<MachineMemOperand*> from both MachineSDNodes and MachineInstr, we should be able to share.

5631–5632

Ditto for stores, I think.

[chandlerc]

Thanks all. Think I have everything so landing. Give a shout if anything else jumps out.

llvm/lib/Target/X86/X86InstrInfo.cpp

5521–5522

See the next patch? ;] It does exactly that.

5631–5632

Yep, also done in the next patch.

llvm/include/llvm/CodeGen/SelectionDAG.h

#endif
   SDNode *UpdateNodeOperands(SDNode *N, SDValue Op1, SDValue Op2,
                                SDValue Op3);
   SDNode *UpdateNodeOperands(SDNode *N, SDValue Op1, SDValue Op2,
                                SDValue Op3, SDValue Op4);
   SDNode *UpdateNodeOperands(SDNode *N, SDValue Op1, SDValue Op2,
                                SDValue Op3, SDValue Op4, SDValue Op5);
   SDNode *UpdateNodeOperands(SDNode *N, ArrayRef<SDValue> Ops);
 
+  /// *Mutate* the specified machine node's memory references to the provided
+  /// list.
+  void setNodeMemRefs(MachineSDNode *N,
+                      ArrayRef<MachineMemOperand *> NewMemRefs);
+
   // Propagates the change in divergence to users
   void updateDivergence(SDNode * N);
 
   /// These are used for target selectors to *mutate* the
   /// specified node to have the specified return type, Target opcode, and
   /// operands.  Note that target opcodes are stored as
   /// ~TargetOpcode in the node opcode field.  The resultant node is returned.
   SDNode *SelectNodeTo(SDNode *N, unsigned MachineOpc, EVT VT);

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

static bool classof(const SDNode *N) {
     return N->getOpcode() == ISD::MSCATTER;
   }
 };
 
 /// An SDNode that represents everything that will be needed
 /// to construct a MachineInstr. These nodes are created during the
 /// instruction selection proper phase.
 class MachineSDNode : public SDNode {
-public:
-  using mmo_iterator = MachineMemOperand **;
-
 private:
   friend class SelectionDAG;
 
   MachineSDNode(unsigned Opc, unsigned Order, const DebugLoc &DL, SDVTList VTs)
       : SDNode(Opc, Order, DL, VTs) {}
 
-  /// Memory reference descriptions for this instruction.
-  mmo_iterator MemRefs = nullptr;
-  mmo_iterator MemRefsEnd = nullptr;
-
-public:
-  mmo_iterator memoperands_begin() const { return MemRefs; }
-  mmo_iterator memoperands_end() const { return MemRefsEnd; }
-  bool memoperands_empty() const { return MemRefsEnd == MemRefs; }
-
-  /// Assign this MachineSDNodes's memory reference descriptor
-  /// list. This does not transfer ownership.
-  void setMemRefs(mmo_iterator NewMemRefs, mmo_iterator NewMemRefsEnd) {
-    for (mmo_iterator MMI = NewMemRefs, MME = NewMemRefsEnd; MMI != MME; ++MMI)
-      assert(*MMI && "Null mem ref detected!");
-    MemRefs = NewMemRefs;
-    MemRefsEnd = NewMemRefsEnd;
+  PointerUnion<MachineMemOperand *, MachineMemOperand **> MemRefs = {};
+
+  // Note that this could be folded into the above `MemRefs` member if doing so
+  // is advantageous at some point. We don't need to store this in most cases.
+  // However, at the moment this doesn't appear to make the allocation any
+  // smaller and makes the code somewhat simpler to read.
+  int NumMemRefs = 0;
+
+public:
+  using mmo_iterator = ArrayRef<MachineMemOperand *>::const_iterator;
+
+  ArrayRef<MachineMemOperand *> memoperands() const {
+    // Special case the common cases.
+    if (NumMemRefs == 0)
+      return {};
+    if (NumMemRefs == 1)
+      return makeArrayRef(MemRefs.getAddrOfPtr1(), 1);
+
+    // Otherwise we have an actual array.
+    return makeArrayRef(MemRefs.get<MachineMemOperand **>(), NumMemRefs);
+  }
+  mmo_iterator memoperands_begin() const { return memoperands().begin(); }
+  mmo_iterator memoperands_end() const { return memoperands().end(); }
+  bool memoperands_empty() const { return memoperands().empty(); }
+
+  /// Clear out the memory reference descriptor list.
+  void clearMemRefs() {
+    MemRefs = nullptr;
+    NumMemRefs = 0;
   }
 
   static bool classof(const SDNode *N) {
     return N->isMachineOpcode();
   }
 };
 
 class SDNodeIterator : public std::iterator<std::forward_iterator_tag,

llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp

#endif
 
   // Add scratch registers as implicit def and early clobber
   if (ScratchRegs)
     for (unsigned i = 0; ScratchRegs[i]; ++i)
       MIB.addReg(ScratchRegs[i], RegState::ImplicitDefine |
                                  RegState::EarlyClobber);
 
   // Transfer all of the memory reference descriptions of this instruction.
-  MIB.setMemRefs(cast<MachineSDNode>(Node)->memoperands_begin(),
-                 cast<MachineSDNode>(Node)->memoperands_end());
+  ArrayRef<MachineMemOperand *> SDNodeMemRefs =
+      cast<MachineSDNode>(Node)->memoperands();
+  MachineMemOperand **MemRefs = MF->allocateMemRefsArray(SDNodeMemRefs.size());
+  std::copy(SDNodeMemRefs.begin(), SDNodeMemRefs.end(), MemRefs);
+  MIB.setMemRefs({MemRefs, SDNodeMemRefs.size()});
 
   // Insert the instruction into position in the block. This needs to
   // happen before any custom inserter hook is called so that the
   // hook knows where in the block to insert the replacement code.
   MBB->insert(InsertPos, MIB);
 
   // The MachineInstr may also define physregs instead of virtregs.  These
   // physreg values can reach other instructions in different ways:

llvm/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp

 // Helper for AddGlue to clone node operands.
 static void CloneNodeWithValues(SDNode *N, SelectionDAG *DAG, ArrayRef<EVT> VTs,
                                 SDValue ExtraOper = SDValue()) {
   SmallVector<SDValue, 8> Ops(N->op_begin(), N->op_end());
   if (ExtraOper.getNode())
     Ops.push_back(ExtraOper);
 
   SDVTList VTList = DAG->getVTList(VTs);
-  MachineSDNode::mmo_iterator Begin = nullptr, End = nullptr;
   MachineSDNode *MN = dyn_cast<MachineSDNode>(N);
 
   // Store memory references.
-  if (MN) {
-    Begin = MN->memoperands_begin();
-    End = MN->memoperands_end();
-  }
+  SmallVector<MachineMemOperand *, 2> MMOs;
+  if (MN)
+    MMOs.assign(MN->memoperands_begin(), MN->memoperands_end());
 
   DAG->MorphNodeTo(N, N->getOpcode(), VTList, Ops);
 
   // Reset the memory references
   if (MN)
-    MN->setMemRefs(Begin, End);
+    DAG->setNodeMemRefs(MN, MMOs);
 }
 
 static bool AddGlue(SDNode *N, SDValue Glue, bool AddGlue, SelectionDAG *DAG) {
   SDNode *GlueDestNode = Glue.getNode();
 
   // Don't add glue from a node to itself.
   if (GlueDestNode == N) return false;
 

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

void SDNode::DropOperands() {
   // Unlike the code in MorphNodeTo that does this, we don't need to
   // watch for dead nodes here.
   for (op_iterator I = op_begin(), E = op_end(); I != E; ) {
     SDUse &Use = *I++;
     Use.set(SDValue());
   }
 }
 
+void SelectionDAG::setNodeMemRefs(MachineSDNode *N,
+                                  ArrayRef<MachineMemOperand *> NewMemRefs) {
+  if (NewMemRefs.empty()) {
+    N->clearMemRefs();
+    return;
+  }
+
+  // Check if we can avoid allocating by storing a single reference directly.
+  if (NewMemRefs.size() == 1) {
+    N->MemRefs = NewMemRefs[0];
+    N->NumMemRefs = 1;
+    return;
+  }
+
+  MachineMemOperand **MemRefsBuffer =
+      Allocator.template Allocate<MachineMemOperand *>(NewMemRefs.size());
+  std::copy(NewMemRefs.begin(), NewMemRefs.end(), MemRefsBuffer);
+  N->MemRefs = MemRefsBuffer;
+  N->NumMemRefs = (int)NewMemRefs.size();
+}
+
 /// SelectNodeTo - These are wrappers around MorphNodeTo that accept a
 /// machine opcode.
 ///
 SDNode *SelectionDAG::SelectNodeTo(SDNode *N, unsigned MachineOpc,
                                    EVT VT) {
   SDVTList VTs = getVTList(VT);
   return SelectNodeTo(N, MachineOpc, VTs, None);
 }
for (SDNode::op_iterator I = N->op_begin(), E = N->op_end(); I != E; ) {
     SDNode *Used = Use.getNode();
     Use.set(SDValue());
     if (Used->use_empty())
       DeadNodeSet.insert(Used);
   }
 
   // For MachineNode, initialize the memory references information.
   if (MachineSDNode *MN = dyn_cast<MachineSDNode>(N))
-    MN->setMemRefs(nullptr, nullptr);
+    MN->clearMemRefs();
 
   // Swap for an appropriately sized array from the recycler.
   removeOperands(N);
   createOperands(N, Ops);
 
   // Delete any nodes that are still dead after adding the uses for the
   // new operands.
   if (!DeadNodeSet.empty()) {

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

static SDValue getLoadStackGuard(SelectionDAG &DAG, const SDLoc &DL,
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
   EVT PtrTy = TLI.getPointerTy(DAG.getDataLayout());
   MachineFunction &MF = DAG.getMachineFunction();
   Value *Global = TLI.getSDagStackGuard(*MF.getFunction().getParent());
   MachineSDNode *Node =
       DAG.getMachineNode(TargetOpcode::LOAD_STACK_GUARD, DL, PtrTy, Chain);
   if (Global) {
     MachinePointerInfo MPInfo(Global);
-    MachineInstr::mmo_iterator MemRefs = MF.allocateMemRefsArray(1);
     auto Flags = MachineMemOperand::MOLoad | MachineMemOperand::MOInvariant |
                  MachineMemOperand::MODereferenceable;
-    *MemRefs = MF.getMachineMemOperand(MPInfo, Flags, PtrTy.getSizeInBits() / 8,
-                                       DAG.getEVTAlignment(PtrTy));
-    Node->setMemRefs(MemRefs, MemRefs + 1);
+    MachineMemOperand *MemRef = MF.getMachineMemOperand(
+        MPInfo, Flags, PtrTy.getSizeInBits() / 8, DAG.getEVTAlignment(PtrTy));
+    DAG.setNodeMemRefs(Node, {MemRef});
   }
   return SDValue(Node, 0);
 }
 
 /// Codegen a new tail for a stack protector check ParentMBB which has had its
 /// tail spliced into a stack protector check success bb.
 ///
 /// For a high level explanation of how this fits into the stack protector

llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

case OPC_MorphNodeTo0: case OPC_MorphNodeTo1: case OPC_MorphNodeTo2: {
       // loads.
       if (EmitNodeInfo & OPFL_MemRefs) {
         // Only attach load or store memory operands if the generated
         // instruction may load or store.
         const MCInstrDesc &MCID = TII->get(TargetOpc);
         bool mayLoad = MCID.mayLoad();
         bool mayStore = MCID.mayStore();
 
-        unsigned NumMemRefs = 0;
-        for (SmallVectorImpl<MachineMemOperand *>::const_iterator I =
-               MatchedMemRefs.begin(), E = MatchedMemRefs.end(); I != E; ++I) {
-          if ((*I)->isLoad()) {
+        // We expect to have relatively few of these so just filter them into a
+        // temporary buffer so that we can easily add them to the instruction.
+        SmallVector<MachineMemOperand *, 4> FilteredMemRefs;
+        for (MachineMemOperand *MMO : MatchedMemRefs) {
+          if (MMO->isLoad()) {
             if (mayLoad)
-              ++NumMemRefs;
-          } else if ((*I)->isStore()) {
+              FilteredMemRefs.push_back(MMO);
+          } else if (MMO->isStore()) {
             if (mayStore)
-              ++NumMemRefs;
+              FilteredMemRefs.push_back(MMO);
           } else {
-            ++NumMemRefs;
+            FilteredMemRefs.push_back(MMO);
           }
         }
 
-        MachineSDNode::mmo_iterator MemRefs =
-          MF->allocateMemRefsArray(NumMemRefs);
-
-        MachineSDNode::mmo_iterator MemRefsPos = MemRefs;
-        for (SmallVectorImpl<MachineMemOperand *>::const_iterator I =
-               MatchedMemRefs.begin(), E = MatchedMemRefs.end(); I != E; ++I) {
-          if ((*I)->isLoad()) {
-            if (mayLoad)
-              *MemRefsPos++ = *I;
-          } else if ((*I)->isStore()) {
-            if (mayStore)
-              *MemRefsPos++ = *I;
-          } else {
-            *MemRefsPos++ = *I;
-          }
-        }
-
-        Res->setMemRefs(MemRefs, MemRefs + NumMemRefs);
+        CurDAG->setNodeMemRefs(Res, FilteredMemRefs);
       }
 
       LLVM_DEBUG(if (!MatchedMemRefs.empty() && Res->memoperands_empty()) dbgs()
                      << "  Dropping mem operands\n";
                  dbgs() << "  " << (IsMorphNodeTo ? "Morphed" : "Created")
                         << " node: ";
                  Res->dump(CurDAG););
 

llvm/lib/CodeGen/StackColoring.cpp

#endif
 
         // Fix the machine instructions.
         int ToSlot = SlotRemap[FromSlot];
         MO.setIndex(ToSlot);
         FixedInstr++;
       }
 
       // We adjust AliasAnalysis information for merged stack slots.
-      MachineSDNode::mmo_iterator NewMemOps =
+      MachineInstr::mmo_iterator NewMemOps =
           MF->allocateMemRefsArray(I.getNumMemOperands());
       unsigned MemOpIdx = 0;
       bool ReplaceMemOps = false;
       for (MachineMemOperand *MMO : I.memoperands()) {
         // If this memory location can be a slot remapped here,
         // we remove AA information.
         bool MayHaveConflictingAAMD = false;
         if (MMO->getAAInfo()) {

llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp

void AArch64DAGToDAGISel::SelectLoad(SDNode *N, unsigned NumVecs, unsigned Opc,
   SDValue SuperReg = SDValue(Ld, 0);
   for (unsigned i = 0; i < NumVecs; ++i)
     ReplaceUses(SDValue(N, i),
         CurDAG->getTargetExtractSubreg(SubRegIdx + i, dl, VT, SuperReg));
 
   ReplaceUses(SDValue(N, NumVecs), SDValue(Ld, 1));
 
   // Transfer memoperands.
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(Ld)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(Ld), {MemOp});
 
   CurDAG->RemoveDeadNode(N);
 }
 
 void AArch64DAGToDAGISel::SelectPostLoad(SDNode *N, unsigned NumVecs,
                                          unsigned Opc, unsigned SubRegIdx) {
   SDLoc dl(N);
   EVT VT = N->getValueType(0);
void AArch64DAGToDAGISel::SelectStore(SDNode *N, unsigned NumVecs,
   bool Is128Bit = VT.getSizeInBits() == 128;
   SmallVector<SDValue, 4> Regs(N->op_begin() + 2, N->op_begin() + 2 + NumVecs);
   SDValue RegSeq = Is128Bit ? createQTuple(Regs) : createDTuple(Regs);
 
   SDValue Ops[] = {RegSeq, N->getOperand(NumVecs + 2), N->getOperand(0)};
   SDNode *St = CurDAG->getMachineNode(Opc, dl, N->getValueType(0), Ops);
 
   // Transfer memoperands.
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(St)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(St), {MemOp});
 
   ReplaceNode(N, St);
 }
 
 void AArch64DAGToDAGISel::SelectPostStore(SDNode *N, unsigned NumVecs,
                                           unsigned Opc) {
   SDLoc dl(N);
   EVT VT = N->getOperand(2)->getValueType(0);
void AArch64DAGToDAGISel::SelectStoreLane(SDNode *N, unsigned NumVecs,
   unsigned LaneNo =
       cast<ConstantSDNode>(N->getOperand(NumVecs + 2))->getZExtValue();
 
   SDValue Ops[] = {RegSeq, CurDAG->getTargetConstant(LaneNo, dl, MVT::i64),
                    N->getOperand(NumVecs + 3), N->getOperand(0)};
   SDNode *St = CurDAG->getMachineNode(Opc, dl, MVT::Other, Ops);
 
   // Transfer memoperands.
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(St)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(St), {MemOp});
 
   ReplaceNode(N, St);
 }
 
 void AArch64DAGToDAGISel::SelectPostStoreLane(SDNode *N, unsigned NumVecs,
                                               unsigned Opc) {
   SDLoc dl(N);
   EVT VT = N->getOperand(2)->getValueType(0);
void AArch64DAGToDAGISel::SelectPostStoreLane(SDNode *N, unsigned NumVecs,
 
   SDValue Ops[] = {RegSeq, CurDAG->getTargetConstant(LaneNo, dl, MVT::i64),
                    N->getOperand(NumVecs + 2), // Base Register
                    N->getOperand(NumVecs + 3), // Incremental
                    N->getOperand(0)};
   SDNode *St = CurDAG->getMachineNode(Opc, dl, ResTys, Ops);
 
   // Transfer memoperands.
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(St)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(St), {MemOp});
 
   ReplaceNode(N, St);
 }
 
 static bool isBitfieldExtractOpFromAnd(SelectionDAG *CurDAG, SDNode *N,
                                        unsigned &Opc, SDValue &Opd0,
                                        unsigned &LSB, unsigned &MSB,
                                        unsigned NumberOfIgnoredLowBits,
bool AArch64DAGToDAGISel::SelectCMP_SWAP(SDNode *N) {
 
   MVT RegTy = MemTy == MVT::i64 ? MVT::i64 : MVT::i32;
   SDValue Ops[] = {N->getOperand(1), N->getOperand(2), N->getOperand(3),
                    N->getOperand(0)};
   SDNode *CmpSwap = CurDAG->getMachineNode(
       Opcode, SDLoc(N),
       CurDAG->getVTList(RegTy, MVT::i32, MVT::Other), Ops);
 
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(CmpSwap)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(CmpSwap), {MemOp});
 
   ReplaceUses(SDValue(N, 0), SDValue(CmpSwap, 0));
   ReplaceUses(SDValue(N, 1), SDValue(CmpSwap, 2));
   CurDAG->RemoveDeadNode(N);
 
   return true;
 }
 
case Intrinsic::aarch64_ldxp: {
       SDValue MemAddr = Node->getOperand(2);
       SDLoc DL(Node);
       SDValue Chain = Node->getOperand(0);
 
       SDNode *Ld = CurDAG->getMachineNode(Op, DL, MVT::i64, MVT::i64,
                                           MVT::Other, MemAddr, Chain);
 
       // Transfer memoperands.
-      MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-      MemOp[0] = cast<MemIntrinsicSDNode>(Node)->getMemOperand();
-      cast<MachineSDNode>(Ld)->setMemRefs(MemOp, MemOp + 1);
+      MachineMemOperand *MemOp =
+          cast<MemIntrinsicSDNode>(Node)->getMemOperand();
+      CurDAG->setNodeMemRefs(cast<MachineSDNode>(Ld), {MemOp});
       ReplaceNode(Node, Ld);
       return;
     }
     case Intrinsic::aarch64_stlxp:
     case Intrinsic::aarch64_stxp: {
       unsigned Op =
           IntNo == Intrinsic::aarch64_stlxp ? AArch64::STLXPX : AArch64::STXPX;
       SDLoc DL(Node);
       SDValue Chain = Node->getOperand(0);
       SDValue ValLo = Node->getOperand(2);
       SDValue ValHi = Node->getOperand(3);
       SDValue MemAddr = Node->getOperand(4);
 
       // Place arguments in the right order.
       SDValue Ops[] = {ValLo, ValHi, MemAddr, Chain};
 
       SDNode *St = CurDAG->getMachineNode(Op, DL, MVT::i32, MVT::Other, Ops);
       // Transfer memoperands.
-      MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-      MemOp[0] = cast<MemIntrinsicSDNode>(Node)->getMemOperand();
-      cast<MachineSDNode>(St)->setMemRefs(MemOp, MemOp + 1);
+      MachineMemOperand *MemOp =
+          cast<MemIntrinsicSDNode>(Node)->getMemOperand();
+      CurDAG->setNodeMemRefs(cast<MachineSDNode>(St), {MemOp});
 
       ReplaceNode(Node, St);
       return;
     }
     case Intrinsic::aarch64_neon_ld1x2:
       if (VT == MVT::v8i8) {
         SelectLoad(Node, 2, AArch64::LD1Twov8b, AArch64::dsub0);
         return;

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

if (Subtarget->hasLSE()) {
     // so lower it here, wrapped in REG_SEQUENCE and EXTRACT_SUBREG.
     SDValue Ops[] = {
         createGPRPairNode(DAG, N->getOperand(2)), // Compare value
         createGPRPairNode(DAG, N->getOperand(3)), // Store value
         N->getOperand(1), // Ptr
         N->getOperand(0), // Chain in
     };
 
-    MachineFunction &MF = DAG.getMachineFunction();
-    MachineSDNode::mmo_iterator MemOp = MF.allocateMemRefsArray(1);
-    MemOp[0] = cast<MemSDNode>(N)->getMemOperand();
+    MachineMemOperand *MemOp = cast<MemSDNode>(N)->getMemOperand();
 
     unsigned Opcode;
-    switch (MemOp[0]->getOrdering()) {
+    switch (MemOp->getOrdering()) {
     case AtomicOrdering::Monotonic:
       Opcode = AArch64::CASPX;
       break;
     case AtomicOrdering::Acquire:
       Opcode = AArch64::CASPAX;
       break;
     case AtomicOrdering::Release:
       Opcode = AArch64::CASPLX;
       break;
     case AtomicOrdering::AcquireRelease:
     case AtomicOrdering::SequentiallyConsistent:
       Opcode = AArch64::CASPALX;
       break;
     default:
       llvm_unreachable("Unexpected ordering!");
     }
 
     MachineSDNode *CmpSwap = DAG.getMachineNode(
         Opcode, SDLoc(N), DAG.getVTList(MVT::Untyped, MVT::Other), Ops);
-    CmpSwap->setMemRefs(MemOp, MemOp + 1);
+    DAG.setNodeMemRefs(CmpSwap, {MemOp});
 
     unsigned SubReg1 = AArch64::sube64, SubReg2 = AArch64::subo64;
     if (DAG.getDataLayout().isBigEndian())
       std::swap(SubReg1, SubReg2);
     Results.push_back(DAG.getTargetExtractSubreg(SubReg1, SDLoc(N), MVT::i64,
                                                  SDValue(CmpSwap, 0)));
     Results.push_back(DAG.getTargetExtractSubreg(SubReg2, SDLoc(N), MVT::i64,
                                                  SDValue(CmpSwap, 0)));
     Results.push_back(SDValue(CmpSwap, 1)); // Chain out
     return;
   }
 
   auto Desired = splitInt128(N->getOperand(2), DAG);
   auto New = splitInt128(N->getOperand(3), DAG);
   SDValue Ops[] = {N->getOperand(1), Desired.first, Desired.second,
                    New.first,        New.second,    N->getOperand(0)};
   SDNode *CmpSwap = DAG.getMachineNode(
       AArch64::CMP_SWAP_128, SDLoc(N),
       DAG.getVTList(MVT::i64, MVT::i64, MVT::i32, MVT::Other), Ops);
 
-  MachineFunction &MF = DAG.getMachineFunction();
-  MachineSDNode::mmo_iterator MemOp = MF.allocateMemRefsArray(1);
-  MemOp[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(CmpSwap)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemSDNode>(N)->getMemOperand();
+  DAG.setNodeMemRefs(cast<MachineSDNode>(CmpSwap), {MemOp});
 
   Results.push_back(SDValue(CmpSwap, 0));
   Results.push_back(SDValue(CmpSwap, 1));
   Results.push_back(SDValue(CmpSwap, 3));
 }
 
 void AArch64TargetLowering::ReplaceNodeResults(
     SDNode *N, SmallVectorImpl<SDValue> &Results, SelectionDAG &DAG) const {

llvm/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp

if (!CmpSwap) {
     }
   }
 
   if (!CmpSwap) {
     SelectCode(N);
     return;
   }
 
-  MachineSDNode::mmo_iterator MMOs = MF->allocateMemRefsArray(1);
-  *MMOs = Mem->getMemOperand();
-  CmpSwap->setMemRefs(MMOs, MMOs + 1);
+  MachineMemOperand *MMO = Mem->getMemOperand();
+  CurDAG->setNodeMemRefs(CmpSwap, {MMO});
 
   unsigned SubReg = Is32 ? AMDGPU::sub0 : AMDGPU::sub0_sub1;
   SDValue Extract
     = CurDAG->getTargetExtractSubreg(SubReg, SL, VT, SDValue(CmpSwap, 0));
 
   ReplaceUses(SDValue(N, 0), Extract);
   ReplaceUses(SDValue(N, 1), SDValue(CmpSwap, 1));
   CurDAG->RemoveDeadNode(N);

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

static bool parseCachePolicy(SDValue CachePolicy, SelectionDAG &DAG,
 
   return Value == 0;
 }
 
 SDValue SITargetLowering::lowerImage(SDValue Op,
                                      const AMDGPU::ImageDimIntrinsicInfo *Intr,
                                      SelectionDAG &DAG) const {
   SDLoc DL(Op);
-  MachineFunction &MF = DAG.getMachineFunction();
   const AMDGPU::MIMGBaseOpcodeInfo *BaseOpcode =
       AMDGPU::getMIMGBaseOpcodeInfo(Intr->BaseOpcode);
   const AMDGPU::MIMGDimInfo *DimInfo = AMDGPU::getMIMGDimInfo(Intr->Dim);
   const AMDGPU::MIMGLZMappingInfo *LZMappingInfo =
       AMDGPU::getMIMGLZMappingInfo(Intr->BaseOpcode);
   unsigned IntrOpcode = Intr->BaseOpcode;
 
   SmallVector<EVT, 2> ResultTypes(Op->value_begin(), Op->value_end());
Opcode = AMDGPU::getMIMGOpcode(IntrOpcode, AMDGPU::MIMGEncGfx8,
                                    NumVDataDwords, NumVAddrDwords);
   if (Opcode == -1)
     Opcode = AMDGPU::getMIMGOpcode(IntrOpcode, AMDGPU::MIMGEncGfx6,
                                    NumVDataDwords, NumVAddrDwords);
   assert(Opcode != -1);
 
   MachineSDNode *NewNode = DAG.getMachineNode(Opcode, DL, ResultTypes, Ops);
   if (auto MemOp = dyn_cast<MemSDNode>(Op)) {
-    MachineInstr::mmo_iterator MemRefs = MF.allocateMemRefsArray(1);
-    *MemRefs = MemOp->getMemOperand();
-    NewNode->setMemRefs(MemRefs, MemRefs + 1);
+    MachineMemOperand *MemRef = MemOp->getMemOperand();
+    DAG.setNodeMemRefs(NewNode, {MemRef});
   }
 
   if (BaseOpcode->AtomicX2) {
     SmallVector<SDValue, 1> Elt;
     DAG.ExtractVectorElements(SDValue(NewNode, 0), Elt, 0, 1);
     return DAG.getMergeValues({Elt[0], SDValue(NewNode, 1)}, DL);
   } else if (IsD16 && !BaseOpcode->Store) {
     MVT LoadVT = Op.getSimpleValueType();
SDVTList NewVTList = HasChain ?
     DAG.getVTList(ResultVT, MVT::Other) : DAG.getVTList(ResultVT);
 
 
   MachineSDNode *NewNode = DAG.getMachineNode(NewOpcode, SDLoc(Node),
                                               NewVTList, Ops);
 
   if (HasChain) {
     // Update chain.
-    NewNode->setMemRefs(Node->memoperands_begin(), Node->memoperands_end());
+    DAG.setNodeMemRefs(NewNode, Node->memoperands());
     DAG.ReplaceAllUsesOfValueWith(SDValue(Node, 1), SDValue(NewNode, 1));
   }
 
   if (BitsSet == 1) {
     assert(Node->hasNUsesOfValue(1, 0));
     SDNode *Copy = DAG.getMachineNode(TargetOpcode::COPY,
                                       SDLoc(Node), Users[Lane]->getValueType(0),
                                       SDValue(NewNode, 0));

llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp

 //===--------------------------------------------------------------------===//
 
 /// getAL - Returns a ARMCC::AL immediate node.
 static inline SDValue getAL(SelectionDAG *CurDAG, const SDLoc &dl) {
   return CurDAG->getTargetConstant((uint64_t)ARMCC::AL, dl, MVT::i32);
 }
 
 void ARMDAGToDAGISel::transferMemOperands(SDNode *N, SDNode *Result) {
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(Result)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(Result), {MemOp});
 }
 
 bool ARMDAGToDAGISel::tryARMIndexedLoad(SDNode *N) {
   LoadSDNode *LD = cast<LoadSDNode>(N);
   ISD::MemIndexedMode AM = LD->getAddressingMode();
   if (AM == ISD::UNINDEXED)
     return false;
 
if (is64BitVector || NumVecs <= 2) {
     Ops.push_back(SDValue(VLdA, 0));
     Ops.push_back(Pred);
     Ops.push_back(Reg0);
     Ops.push_back(Chain);
     VLd = CurDAG->getMachineNode(QOpcodes1[OpcodeIndex], dl, ResTys, Ops);
   }
 
   // Transfer memoperands.
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(VLd)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(VLd), {MemOp});
 
   if (NumVecs == 1) {
     ReplaceNode(N, VLd);
     return;
   }
 
   // Extract out the subregisters.
   SDValue SuperReg = SDValue(VLd, 0);
void ARMDAGToDAGISel::SelectVST(SDNode *N, bool isUpdating, unsigned NumVecs,
   SDValue MemAddr, Align;
   bool IsIntrinsic = !isUpdating;  // By coincidence, all supported updating
                                    // nodes are not intrinsics.
   unsigned AddrOpIdx = IsIntrinsic ? 2 : 1;
   unsigned Vec0Idx = 3; // AddrOpIdx + (isUpdating ? 2 : 1)
   if (!SelectAddrMode6(N, N->getOperand(AddrOpIdx), MemAddr, Align))
     return;
 
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+  MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
 
   SDValue Chain = N->getOperand(0);
   EVT VT = N->getOperand(Vec0Idx).getValueType();
   bool is64BitVector = VT.is64BitVector();
   Align = GetVLDSTAlign(Align, dl, NumVecs, is64BitVector);
 
   unsigned OpcodeIndex;
   switch (VT.getSimpleVT().SimpleTy) {
if (is64BitVector || NumVecs <= 2) {
     }
     Ops.push_back(SrcReg);
     Ops.push_back(Pred);
     Ops.push_back(Reg0);
     Ops.push_back(Chain);
     SDNode *VSt = CurDAG->getMachineNode(Opc, dl, ResTys, Ops);
 
     // Transfer memoperands.
-    cast<MachineSDNode>(VSt)->setMemRefs(MemOp, MemOp + 1);
+    CurDAG->setNodeMemRefs(cast<MachineSDNode>(VSt), {MemOp});
 
     ReplaceNode(N, VSt);
     return;
   }
 
   // Otherwise, quad registers are stored with two separate instructions,
   // where one stores the even registers and the other stores the odd registers.
 
   // Form the QQQQ REG_SEQUENCE.
   SDValue V0 = N->getOperand(Vec0Idx + 0);
   SDValue V1 = N->getOperand(Vec0Idx + 1);
   SDValue V2 = N->getOperand(Vec0Idx + 2);
   SDValue V3 = (NumVecs == 3)
     ? SDValue(CurDAG->getMachineNode(TargetOpcode::IMPLICIT_DEF, dl, VT), 0)
     : N->getOperand(Vec0Idx + 3);
   SDValue RegSeq = SDValue(createQuadQRegsNode(MVT::v8i64, V0, V1, V2, V3), 0);
 
   // Store the even D registers.  This is always an updating store, so that it
   // provides the address to the second store for the odd subregs.
   const SDValue OpsA[] = { MemAddr, Align, Reg0, RegSeq, Pred, Reg0, Chain };
   SDNode *VStA = CurDAG->getMachineNode(QOpcodes0[OpcodeIndex], dl,
                                         MemAddr.getValueType(),
                                         MVT::Other, OpsA);
-  cast<MachineSDNode>(VStA)->setMemRefs(MemOp, MemOp + 1);
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(VStA), {MemOp});
   Chain = SDValue(VStA, 1);
 
   // Store the odd D registers.
   Ops.push_back(SDValue(VStA, 0));
   Ops.push_back(Align);
   if (isUpdating) {
     SDValue Inc = N->getOperand(AddrOpIdx + 1);
     assert(isa<ConstantSDNode>(Inc.getNode()) &&
            "only constant post-increment update allowed for VST3/4");
     (void)Inc;
     Ops.push_back(Reg0);
   }
   Ops.push_back(RegSeq);
   Ops.push_back(Pred);
   Ops.push_back(Reg0);
   Ops.push_back(Chain);
   SDNode *VStB = CurDAG->getMachineNode(QOpcodes1[OpcodeIndex], dl, ResTys,
                                         Ops);
-  cast<MachineSDNode>(VStB)->setMemRefs(MemOp, MemOp + 1);
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(VStB), {MemOp});
   ReplaceNode(N, VStB);
 }
 
 void ARMDAGToDAGISel::SelectVLDSTLane(SDNode *N, bool IsLoad, bool isUpdating,
                                       unsigned NumVecs,
                                       const uint16_t *DOpcodes,
                                       const uint16_t *QOpcodes) {
   assert(NumVecs >=2 && NumVecs <= 4 && "VLDSTLane NumVecs out-of-range");
   SDLoc dl(N);
 
   SDValue MemAddr, Align;
   bool IsIntrinsic = !isUpdating;  // By coincidence, all supported updating
                                    // nodes are not intrinsics.
   unsigned AddrOpIdx = IsIntrinsic ? 2 : 1;
   unsigned Vec0Idx = 3; // AddrOpIdx + (isUpdating ? 2 : 1)
   if (!SelectAddrMode6(N, N->getOperand(AddrOpIdx), MemAddr, Align))
     return;
 
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+  MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
 
   SDValue Chain = N->getOperand(0);
   unsigned Lane =
     cast<ConstantSDNode>(N->getOperand(Vec0Idx + NumVecs))->getZExtValue();
   EVT VT = N->getOperand(Vec0Idx).getValueType();
   bool is64BitVector = VT.is64BitVector();
 
   unsigned Alignment = 0;
void ARMDAGToDAGISel::SelectVLDSTLane(SDNode *N, bool IsLoad, bool isUpdating,
   Ops.push_back(getI32Imm(Lane, dl));
   Ops.push_back(Pred);
   Ops.push_back(Reg0);
   Ops.push_back(Chain);
 
   unsigned Opc = (is64BitVector ? DOpcodes[OpcodeIndex] :
                                   QOpcodes[OpcodeIndex]);
   SDNode *VLdLn = CurDAG->getMachineNode(Opc, dl, ResTys, Ops);
-  cast<MachineSDNode>(VLdLn)->setMemRefs(MemOp, MemOp + 1);
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(VLdLn), {MemOp});
   if (!IsLoad) {
     ReplaceNode(N, VLdLn);
     return;
   }
 
   // Extract the subregisters.
   SuperReg = SDValue(VLdLn, 0);
   static_assert(ARM::dsub_7 == ARM::dsub_0 + 7 &&
if (is64BitVector || NumVecs == 1) {
 
     SDValue SuperReg = SDValue(VLdA, 0);
     Chain = SDValue(VLdA, 1);
     const SDValue OpsB[] = { MemAddr, Align, SuperReg, Pred, Reg0, Chain };
     VLdDup = CurDAG->getMachineNode(QOpcodes1[OpcodeIndex], dl, ResTys, OpsB);
   }
 
   // Transfer memoperands.
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(VLdDup)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(VLdDup), {MemOp});
 
   // Extract the subregisters.
   if (NumVecs == 1) {
     ReplaceUses(SDValue(N, 0), SDValue(VLdDup, 0));
   } else {
     SDValue SuperReg = SDValue(VLdDup, 0);
     static_assert(ARM::dsub_7 == ARM::dsub_0 + 7, "Unexpected subreg numbering");
     unsigned SubIdx = is64BitVector ? ARM::dsub_0 : ARM::qsub_0;
else
     llvm_unreachable("Unknown AtomicCmpSwap type");
 
   SDValue Ops[] = {N->getOperand(1), N->getOperand(2), N->getOperand(3),
                    N->getOperand(0)};
   SDNode *CmpSwap = CurDAG->getMachineNode(
       Opcode, SDLoc(N),
       CurDAG->getVTList(MVT::i32, MVT::i32, MVT::Other), Ops);
 
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(CmpSwap)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(CmpSwap), {MemOp});
 
   ReplaceUses(SDValue(N, 0), SDValue(CmpSwap, 0));
   ReplaceUses(SDValue(N, 1), SDValue(CmpSwap, 2));
   CurDAG->RemoveDeadNode(N);
 }
 
 static Optional<std::pair<unsigned, unsigned>>
 getContiguousRangeOfSetBits(const APInt &A) {
if (ConstantMaterializationCost(Val) > 2) {
         };
         ResNode = CurDAG->getMachineNode(ARM::LDRcp, dl, MVT::i32, MVT::Other,
                                          Ops);
       }
       // Annotate the Node with memory operand information so that MachineInstr
       // queries work properly. This e.g. gives the register allocation the
       // required information for rematerialization.
       MachineFunction& MF = CurDAG->getMachineFunction();
-      MachineSDNode::mmo_iterator MemOp = MF.allocateMemRefsArray(1);
-      MemOp[0] = MF.getMachineMemOperand(
-          MachinePointerInfo::getConstantPool(MF),
+      MachineMemOperand *MemOp =
+          MF.getMachineMemOperand(MachinePointerInfo::getConstantPool(MF),
                                   MachineMemOperand::MOLoad, 4, 4);
 
-      cast<MachineSDNode>(ResNode)->setMemRefs(MemOp, MemOp+1);
+      CurDAG->setNodeMemRefs(cast<MachineSDNode>(ResNode), {MemOp});
 
       ReplaceNode(N, ResNode);
       return;
     }
 
     // Other cases are autogenerated.
     break;
   }
case Intrinsic::arm_ldrexd: {
         ResTys.push_back(MVT::Untyped);
       ResTys.push_back(MVT::Other);
 
       // Place arguments in the right order.
       SDValue Ops[] = {MemAddr, getAL(CurDAG, dl),
                        CurDAG->getRegister(0, MVT::i32), Chain};
       SDNode *Ld = CurDAG->getMachineNode(NewOpc, dl, ResTys, Ops);
       // Transfer memoperands.
-      MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-      MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
-      cast<MachineSDNode>(Ld)->setMemRefs(MemOp, MemOp + 1);
+      MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+      CurDAG->setNodeMemRefs(cast<MachineSDNode>(Ld), {MemOp});
 
       // Remap uses.
       SDValue OutChain = isThumb ? SDValue(Ld, 2) : SDValue(Ld, 1);
       if (!SDValue(N, 0).use_empty()) {
         SDValue Result;
         if (isThumb)
           Result = SDValue(Ld, 0);
         else {
case Intrinsic::arm_strexd: {
       Ops.push_back(Chain);
 
       bool IsRelease = IntNo == Intrinsic::arm_stlexd;
       unsigned NewOpc = isThumb ? (IsRelease ? ARM::t2STLEXD : ARM::t2STREXD)
                                 : (IsRelease ? ARM::STLEXD : ARM::STREXD);
 
       SDNode *St = CurDAG->getMachineNode(NewOpc, dl, ResTys, Ops);
       // Transfer memoperands.
-      MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-      MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
-      cast<MachineSDNode>(St)->setMemRefs(MemOp, MemOp + 1);
+      MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+      CurDAG->setNodeMemRefs(cast<MachineSDNode>(St), {MemOp});
 
       ReplaceNode(N, St);
       return;
     }
 
     case Intrinsic::arm_neon_vld1: {
       static const uint16_t DOpcodes[] = { ARM::VLD1d8, ARM::VLD1d16,
                                            ARM::VLD1d32, ARM::VLD1d64 };

llvm/lib/Target/ARM/ARMISelLowering.cpp

static void ReplaceCMP_SWAP_64Results(SDNode *N,
   SDValue Ops[] = {N->getOperand(1),
                    createGPRPairNode(DAG, N->getOperand(2)),
                    createGPRPairNode(DAG, N->getOperand(3)),
                    N->getOperand(0)};
   SDNode *CmpSwap = DAG.getMachineNode(
       ARM::CMP_SWAP_64, SDLoc(N),
       DAG.getVTList(MVT::Untyped, MVT::i32, MVT::Other), Ops);
 
-  MachineFunction &MF = DAG.getMachineFunction();
-  MachineSDNode::mmo_iterator MemOp = MF.allocateMemRefsArray(1);
-  MemOp[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(CmpSwap)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemSDNode>(N)->getMemOperand();
+  DAG.setNodeMemRefs(cast<MachineSDNode>(CmpSwap), {MemOp});
 
   bool isBigEndian = DAG.getDataLayout().isBigEndian();
 
   Results.push_back(
       DAG.getTargetExtractSubreg(isBigEndian ? ARM::gsub_1 : ARM::gsub_0,
                                  SDLoc(N), MVT::i32, SDValue(CmpSwap, 0)));
   Results.push_back(
       DAG.getTargetExtractSubreg(isBigEndian ? ARM::gsub_0 : ARM::gsub_1,

llvm/lib/Target/Hexagon/HexagonISelDAGToDAG.cpp

if (isAlignedMemNode(LD)) {
       Opcode = IsValidInc ? Hexagon::V6_vL32Ub_pi : Hexagon::V6_vL32Ub_ai;
     }
     break;
   default:
     llvm_unreachable("Unexpected memory type in indexed load");
   }
 
   SDValue IncV = CurDAG->getTargetConstant(Inc, dl, MVT::i32);
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = LD->getMemOperand();
+  MachineMemOperand *MemOp = LD->getMemOperand();
 
   auto getExt64 = [this,ExtType] (MachineSDNode *N, const SDLoc &dl)
         -> MachineSDNode* {
     if (ExtType == ISD::ZEXTLOAD || ExtType == ISD::EXTLOAD) {
       SDValue Zero = CurDAG->getTargetConstant(0, dl, MVT::i32);
       return CurDAG->getMachineNode(Hexagon::A4_combineir, dl, MVT::i64,
                                     Zero, SDValue(N, 0));
     }
if (ValueVT == MVT::i64 && ExtType != ISD::NON_EXTLOAD) {
     assert(LoadedVT.getSizeInBits() <= 32);
     ValueVT = MVT::i32;
   }
 
   if (IsValidInc) {
     MachineSDNode *L = CurDAG->getMachineNode(Opcode, dl, ValueVT,
                                               MVT::i32, MVT::Other, Base,
                                               IncV, Chain);
-    L->setMemRefs(MemOp, MemOp+1);
+    CurDAG->setNodeMemRefs(L, {MemOp});
     To[1] = SDValue(L, 1); // Next address.
     To[2] = SDValue(L, 2); // Chain.
     // Handle special case for extension to i64.
     if (LD->getValueType(0) == MVT::i64)
       L = getExt64(L, dl);
     To[0] = SDValue(L, 0); // Loaded (extended) value.
   } else {
     SDValue Zero = CurDAG->getTargetConstant(0, dl, MVT::i32);
     MachineSDNode *L = CurDAG->getMachineNode(Opcode, dl, ValueVT, MVT::Other,
                                               Base, Zero, Chain);
-    L->setMemRefs(MemOp, MemOp+1);
+    CurDAG->setNodeMemRefs(L, {MemOp});
     To[2] = SDValue(L, 1); // Chain.
     MachineSDNode *A = CurDAG->getMachineNode(Hexagon::A2_addi, dl, MVT::i32,
                                               Base, IncV);
     To[1] = SDValue(A, 0); // Next address.
     // Handle special case for extension to i64.
     if (LD->getValueType(0) == MVT::i64)
       L = getExt64(L, dl);
     To[0] = SDValue(L, 0); // Loaded (extended) value.
if (FLI != LoadBrevMap.end()) {
     EVT RTys[] = { ValTy, MVT::i32, MVT::Other };
     // Operands of Intrinsic: {chain, enum ID of intrinsic, baseptr,
     // modifier}.
     // Operands of target instruction: { Base, Modifier, Chain }.
     MachineSDNode *Res = CurDAG->getMachineNode(
         FLI->second, dl, RTys,
         {IntN->getOperand(2), IntN->getOperand(3), IntN->getOperand(0)});
 
-    MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-    MemOp[0] = cast<MemIntrinsicSDNode>(IntN)->getMemOperand();
-    Res->setMemRefs(MemOp, MemOp + 1);
+    MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(IntN)->getMemOperand();
+    CurDAG->setNodeMemRefs(Res, {MemOp});
 
     ReplaceUses(SDValue(IntN, 0), SDValue(Res, 0));
     ReplaceUses(SDValue(IntN, 1), SDValue(Res, 1));
     ReplaceUses(SDValue(IntN, 2), SDValue(Res, 2));
     CurDAG->RemoveDeadNode(IntN);
     return true;
   }
   return false;
void HexagonDAGToDAGISel::SelectIndexedStore(StoreSDNode *ST, const SDLoc &dl) {
 
   if (ST->isTruncatingStore() && ValueVT.getSizeInBits() == 64) {
     assert(StoredVT.getSizeInBits() < 64 && "Not a truncating store");
     Value = CurDAG->getTargetExtractSubreg(Hexagon::isub_lo,
                                            dl, MVT::i32, Value);
   }
 
   SDValue IncV = CurDAG->getTargetConstant(Inc, dl, MVT::i32);
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = ST->getMemOperand();
+  MachineMemOperand *MemOp = ST->getMemOperand();
 
   //                  Next address   Chain
   SDValue From[2] = { SDValue(ST,0), SDValue(ST,1) };
   SDValue To[2];
 
   if (IsValidInc) {
     // Build post increment store.
     SDValue Ops[] = { Base, IncV, Value, Chain };
     MachineSDNode *S = CurDAG->getMachineNode(Opcode, dl, MVT::i32, MVT::Other,
                                               Ops);
-    S->setMemRefs(MemOp, MemOp + 1);
+    CurDAG->setNodeMemRefs(S, {MemOp});
     To[0] = SDValue(S, 0);
     To[1] = SDValue(S, 1);
   } else {
     SDValue Zero = CurDAG->getTargetConstant(0, dl, MVT::i32);
     SDValue Ops[] = { Base, Zero, Value, Chain };
     MachineSDNode *S = CurDAG->getMachineNode(Opcode, dl, MVT::Other, Ops);
-    S->setMemRefs(MemOp, MemOp + 1);
+    CurDAG->setNodeMemRefs(S, {MemOp});
     To[1] = SDValue(S, 0);
     MachineSDNode *A = CurDAG->getMachineNode(Hexagon::A2_addi, dl, MVT::i32,
                                               Base, IncV);
     To[0] = SDValue(A, 0);
   }
 
   ReplaceUses(From, To, 2);
   CurDAG->RemoveDeadNode(ST);

llvm/lib/Target/Hexagon/HexagonISelDAGToDAGHVX.cpp

case Intrinsic::hexagon_V6_vgathermhwq_128B:
     Opcode = Hexagon::V6_vgathermhwq_pseudo;
     break;
   }
 
   SDVTList VTs = CurDAG->getVTList(MVT::Other);
   SDValue Ops[] = { Address, Predicate, Base, Modifier, Offset, Chain };
   SDNode *Result = CurDAG->getMachineNode(Opcode, dl, VTs, Ops);
 
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(Result)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(Result), {MemOp});
 
   ReplaceNode(N, Result);
 }
 
 void HexagonDAGToDAGISel::SelectV65Gather(SDNode *N) {
   const SDLoc &dl(N);
   SDValue Chain = N->getOperand(0);
   SDValue Address = N->getOperand(2);
case Intrinsic::hexagon_V6_vgathermhw_128B:
     Opcode = Hexagon::V6_vgathermhw_pseudo;
     break;
   }
 
   SDVTList VTs = CurDAG->getVTList(MVT::Other);
   SDValue Ops[] = { Address, Base, Modifier, Offset, Chain };
   SDNode *Result = CurDAG->getMachineNode(Opcode, dl, VTs, Ops);
 
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemIntrinsicSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(Result)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemIntrinsicSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(Result), {MemOp});
 
   ReplaceNode(N, Result);
 }
 
 void HexagonDAGToDAGISel::SelectHVXDualOutput(SDNode *N) {
   unsigned IID = cast<ConstantSDNode>(N->getOperand(0))->getZExtValue();
   SDNode *Result;
   switch (IID) {

llvm/lib/Target/MSP430/MSP430ISelDAGToDAG.cpp

if (N1.getOpcode() == ISD::LOAD &&
       N1.hasOneUse() &&
       IsLegalToFold(N1, Op, Op, OptLevel)) {
     LoadSDNode *LD = cast<LoadSDNode>(N1);
     if (!isValidIndexedLoad(LD))
       return false;
 
     MVT VT = LD->getMemoryVT().getSimpleVT();
     unsigned Opc = (VT == MVT::i16 ? Opc16 : Opc8);
-    MachineSDNode::mmo_iterator MemRefs0 = MF->allocateMemRefsArray(1);
-    MemRefs0[0] = cast<MemSDNode>(N1)->getMemOperand();
+    MachineMemOperand *MemRef = cast<MemSDNode>(N1)->getMemOperand();
     SDValue Ops0[] = { N2, LD->getBasePtr(), LD->getChain() };
     SDNode *ResNode =
       CurDAG->SelectNodeTo(Op, Opc, VT, MVT::i16, MVT::Other, Ops0);
-    cast<MachineSDNode>(ResNode)->setMemRefs(MemRefs0, MemRefs0 + 1);
+    CurDAG->setNodeMemRefs(cast<MachineSDNode>(ResNode), {MemRef});
     // Transfer chain.
     ReplaceUses(SDValue(N1.getNode(), 2), SDValue(ResNode, 2));
     // Transfer writeback.
     ReplaceUses(SDValue(N1.getNode(), 1), SDValue(ResNode, 1));
     return true;
   }
 
   return false;

llvm/lib/Target/NVPTX/NVPTXISelDAGToDAG.cpp

SDValue Ops[] = { getI32Imm(isVolatile, dl), getI32Imm(CodeAddrSpace, dl),
                       getI32Imm(fromTypeWidth, dl), N1, Chain };
     NVPTXLD = CurDAG->getMachineNode(Opcode.getValue(), dl, TargetVT,
                                      MVT::Other, Ops);
   }
 
   if (!NVPTXLD)
     return false;
 
-  MachineSDNode::mmo_iterator MemRefs0 = MF->allocateMemRefsArray(1);
-  MemRefs0[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(NVPTXLD)->setMemRefs(MemRefs0, MemRefs0 + 1);
+  MachineMemOperand *MemRef = cast<MemSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(NVPTXLD), {MemRef});
 
   ReplaceNode(N, NVPTXLD);
   return true;
 }
 
 bool NVPTXDAGToDAGISel::tryLoadVector(SDNode *N) {
 
   SDValue Chain = N->getOperand(0);
if (SelectDirectAddr(Op1, Addr)) {
     if (!Opcode)
       return false;
     SDValue Ops[] = { getI32Imm(IsVolatile, DL), getI32Imm(CodeAddrSpace, DL),
                       getI32Imm(VecType, DL), getI32Imm(FromType, DL),
                       getI32Imm(FromTypeWidth, DL), Op1, Chain };
     LD = CurDAG->getMachineNode(Opcode.getValue(), DL, N->getVTList(), Ops);
   }
 
-  MachineSDNode::mmo_iterator MemRefs0 = MF->allocateMemRefsArray(1);
-  MemRefs0[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(LD)->setMemRefs(MemRefs0, MemRefs0 + 1);
+  MachineMemOperand *MemRef = cast<MemSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(LD), {MemRef});
 
   ReplaceNode(N, LD);
   return true;
 }
 
 bool NVPTXDAGToDAGISel::tryLDGLDU(SDNode *N) {
 
   SDValue Chain = N->getOperand(0);
if (TM.is64Bit()) {
       }
     }
     if (!Opcode)
       return false;
     SDValue Ops[] = { Op1, Chain };
     LD = CurDAG->getMachineNode(Opcode.getValue(), DL, InstVTList, Ops);
   }
 
-  MachineSDNode::mmo_iterator MemRefs0 = MF->allocateMemRefsArray(1);
-  MemRefs0[0] = Mem->getMemOperand();
-  cast<MachineSDNode>(LD)->setMemRefs(MemRefs0, MemRefs0 + 1);
+  MachineMemOperand *MemRef = Mem->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(LD), {MemRef});
 
   // For automatic generation of LDG (through SelectLoad[Vector], not the
   // intrinsics), we may have an extending load like:
   //
   //   i32,ch = load<LD1[%data1(addrspace=1)], zext from i8> t0, t7, undef:i64
   //
   // In this case, the matching logic above will select a load for the original
   // memory type (in this case, i8) and our types will not match (the node needs
SDValue Ops[] = {Value,
                      BasePtr,
                      Chain};
     NVPTXST = CurDAG->getMachineNode(Opcode.getValue(), dl, MVT::Other, Ops);
   }
 
   if (!NVPTXST)
     return false;
 
-  MachineSDNode::mmo_iterator MemRefs0 = MF->allocateMemRefsArray(1);
-  MemRefs0[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(NVPTXST)->setMemRefs(MemRefs0, MemRefs0 + 1);
+  MachineMemOperand *MemRef = cast<MemSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(NVPTXST), {MemRef});
   ReplaceNode(N, NVPTXST);
   return true;
 }
 
 bool NVPTXDAGToDAGISel::tryStoreVector(SDNode *N) {
   SDValue Chain = N->getOperand(0);
   SDValue Op1 = N->getOperand(1);
   SDValue Addr, Offset, Base;
bool NVPTXDAGToDAGISel::tryStoreVector(SDNode *N) {
 
   if (!Opcode)
     return false;
 
   StOps.push_back(Chain);
 
   ST = CurDAG->getMachineNode(Opcode.getValue(), DL, MVT::Other, StOps);
 
-  MachineSDNode::mmo_iterator MemRefs0 = MF->allocateMemRefsArray(1);
-  MemRefs0[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(ST)->setMemRefs(MemRefs0, MemRefs0 + 1);
+  MachineMemOperand *MemRef = cast<MemSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(ST), {MemRef});
 
   ReplaceNode(N, ST);
   return true;
 }
 
 bool NVPTXDAGToDAGISel::tryLoadParam(SDNode *Node) {
   SDValue Chain = Node->getOperand(0);
   SDValue Offset = Node->getOperand(2);
Opcode = pickOpcodeForVT(Mem->getMemoryVT().getSimpleVT().SimpleTy,
                              NVPTX::StoreRetvalV4F16, NVPTX::StoreRetvalV4F16x2,
                              NVPTX::StoreRetvalV4F32, None);
     break;
   }
   if (!Opcode)
     return false;
 
   SDNode *Ret = CurDAG->getMachineNode(Opcode.getValue(), DL, MVT::Other, Ops);
-  MachineSDNode::mmo_iterator MemRefs0 = MF->allocateMemRefsArray(1);
-  MemRefs0[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(Ret)->setMemRefs(MemRefs0, MemRefs0 + 1);
+  MachineMemOperand *MemRef = cast<MemSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(Ret), {MemRef});
 
   ReplaceNode(N, Ret);
   return true;
 }
 
 bool NVPTXDAGToDAGISel::tryStoreParam(SDNode *N) {
   SDLoc DL(N);
   SDValue Chain = N->getOperand(0);
case NVPTXISD::StoreParamS32: {
     Ops[0] = SDValue(Cvt, 0);
     break;
   }
   }
 
   SDVTList RetVTs = CurDAG->getVTList(MVT::Other, MVT::Glue);
   SDNode *Ret =
       CurDAG->getMachineNode(Opcode.getValue(), DL, RetVTs, Ops);
-  MachineSDNode::mmo_iterator MemRefs0 = MF->allocateMemRefsArray(1);
-  MemRefs0[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(Ret)->setMemRefs(MemRefs0, MemRefs0 + 1);
+  MachineMemOperand *MemRef = cast<MemSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(Ret), {MemRef});
 
   ReplaceNode(N, Ret);
   return true;
 }
 
 bool NVPTXDAGToDAGISel::tryTextureIntrinsic(SDNode *N) {
   unsigned Opc = 0;
 

llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp

if (AddrOp.getOpcode() == ISD::ADD)
     return isIntS16Immediate(AddrOp.getOperand(1), Imm) && !(Imm % Val);
 
   // If the address comes from the outside, the offset will be zero.
   return AddrOp.getOpcode() == ISD::CopyFromReg;
 }
 
 void PPCDAGToDAGISel::transferMemOperands(SDNode *N, SDNode *Result) {
   // Transfer memoperands.
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-  MemOp[0] = cast<MemSDNode>(N)->getMemOperand();
-  cast<MachineSDNode>(Result)->setMemRefs(MemOp, MemOp + 1);
+  MachineMemOperand *MemOp = cast<MemSDNode>(N)->getMemOperand();
+  CurDAG->setNodeMemRefs(cast<MachineSDNode>(Result), {MemOp});
 }
 
 /// This method returns a node after flipping the MSB of each element
 /// of vector integer type. Additionally, if SignBitVec is non-null,
 /// this method sets a node with one at MSB of all elements
 /// and zero at other bits in SignBitVec.
 MachineSDNode *
 PPCDAGToDAGISel::flipSignBit(const SDValue &N, SDNode **SignBitVec) {
if (PPCSubTarget->hasVSX() && (N->getValueType(0) == MVT::v2f64 ||
         SDValue Base, Offset;
 
         if (LD->isUnindexed() && LD->hasOneUse() && Op1.hasOneUse() &&
             (LD->getMemoryVT() == MVT::f64 ||
              LD->getMemoryVT() == MVT::i64) &&
             SelectAddrIdxOnly(LD->getBasePtr(), Base, Offset)) {
           SDValue Chain = LD->getChain();
           SDValue Ops[] = { Base, Offset, Chain };
-          MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-          MemOp[0] = LD->getMemOperand();
+          MachineMemOperand *MemOp = LD->getMemOperand();
           SDNode *NewN = CurDAG->SelectNodeTo(N, PPC::LXVDSX,
                                               N->getValueType(0), Ops);
-          cast<MachineSDNode>(NewN)->setMemRefs(MemOp, MemOp + 1);
+          CurDAG->setNodeMemRefs(cast<MachineSDNode>(NewN), {MemOp});
           return;
         }
       }
 
       // For little endian, we must swap the input operands and adjust
       // the mask elements (reverse and invert them).
       if (PPCSubTarget->isLittleEndian()) {
         std::swap(Op1, Op2);

llvm/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp

bool SystemZDAGToDAGISel::tryFoldLoadStoreIntoMemOperand(SDNode *Node) {
 
   SDValue Base, Disp;
   if (!selectBDAddr20Only(StoreNode->getBasePtr(), Base, Disp))
     return false;
 
   SDValue Ops[] = { Base, Disp, Operand, InputChain };
   MachineSDNode *Result =
     CurDAG->getMachineNode(NewOpc, DL, MVT::i32, MVT::Other, Ops);
-
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(2);
-  MemOp[0] = StoreNode->getMemOperand();
-  MemOp[1] = LoadNode->getMemOperand();
-  Result->setMemRefs(MemOp, MemOp + 2);
+  CurDAG->setNodeMemRefs(
+      Result, {StoreNode->getMemOperand(), LoadNode->getMemOperand()});
 
   ReplaceUses(SDValue(StoreNode, 0), SDValue(Result, 1));
   ReplaceUses(SDValue(StoredVal.getNode(), 1), SDValue(Result, 0));
   CurDAG->RemoveDeadNode(Node);
   return true;
 }
 
 bool SystemZDAGToDAGISel::canUseBlockOperation(StoreSDNode *Store,

llvm/lib/Target/X86/X86ISelDAGToDAG.cpp

if (Opc == X86ISD::ADC || Opc == X86ISD::SBB) {
                                       Ops);
     }
     break;
   }
   default:
     llvm_unreachable("Invalid opcode!");
   }
 
-  MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(2);
-  MemOp[0] = StoreNode->getMemOperand();
-  MemOp[1] = LoadNode->getMemOperand();
-  Result->setMemRefs(MemOp, MemOp + 2);
+  MachineMemOperand *MemOps[] = {StoreNode->getMemOperand(),
+                                 LoadNode->getMemOperand()};
+  CurDAG->setNodeMemRefs(Result, MemOps);
 
   // Update Load Chain uses as well.
   ReplaceUses(SDValue(LoadNode, 1), SDValue(Result, 1));
   ReplaceUses(SDValue(StoreNode, 0), SDValue(Result, 1));
   ReplaceUses(SDValue(StoredVal.getNode(), 1), SDValue(Result, 0));
   CurDAG->RemoveDeadNode(Node);
   return true;
 }
if (MayFoldLoad && N1->getOpcode() == ISD::BITCAST && N1->hasOneUse() &&
     SDValue Load = N1.getOperand(0);
     SDValue Ops[] = { N0, Tmp0, Tmp1, Tmp2, Tmp3, Tmp4, Imm,
                       Load.getOperand(0) };
     SDVTList VTs = CurDAG->getVTList(VT, MVT::i32, MVT::Other);
     MachineSDNode *CNode = CurDAG->getMachineNode(MOpc, dl, VTs, Ops);
     // Update the chain.
     ReplaceUses(Load.getValue(1), SDValue(CNode, 2));
     // Record the mem-refs
-    MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-    MemOp[0] = cast<LoadSDNode>(Load)->getMemOperand();
-    CNode->setMemRefs(MemOp, MemOp + 1);
+    CurDAG->setNodeMemRefs(CNode, {cast<LoadSDNode>(Load)->getMemOperand()});
     return CNode;
   }
 
   SDValue Ops[] = { N0, N1, Imm };
   SDVTList VTs = CurDAG->getVTList(VT, MVT::i32);
   MachineSDNode *CNode = CurDAG->getMachineNode(ROpc, dl, VTs, Ops);
   return CNode;
 }
if (MayFoldLoad && N2->getOpcode() == ISD::BITCAST && N2->hasOneUse() &&
     SDValue Ops[] = { N0, Tmp0, Tmp1, Tmp2, Tmp3, Tmp4, Imm,
                       Load.getOperand(0), InFlag };
     SDVTList VTs = CurDAG->getVTList(VT, MVT::i32, MVT::Other, MVT::Glue);
     MachineSDNode *CNode = CurDAG->getMachineNode(MOpc, dl, VTs, Ops);
     InFlag = SDValue(CNode, 3);
     // Update the chain.
     ReplaceUses(Load.getValue(1), SDValue(CNode, 2));
     // Record the mem-refs
-    MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-    MemOp[0] = cast<LoadSDNode>(Load)->getMemOperand();
-    CNode->setMemRefs(MemOp, MemOp + 1);
+    CurDAG->setNodeMemRefs(CNode, {cast<LoadSDNode>(Load)->getMemOperand()});
     return CNode;
   }
 
   SDValue Ops[] = { N0, N2, Imm, InFlag };
   SDVTList VTs = CurDAG->getVTList(VT, MVT::i32, MVT::Glue);
   MachineSDNode *CNode = CurDAG->getMachineNode(ROpc, dl, VTs, Ops);
   InFlag = SDValue(CNode, 2);
   return CNode;
if (foldedLoad) {
         CNode = CurDAG->getMachineNode(MOpc, dl, VTs, Ops);
         Chain = SDValue(CNode, 0);
         InFlag = SDValue(CNode, 1);
       }
 
       // Update the chain.
       ReplaceUses(N1.getValue(1), Chain);
       // Record the mem-refs
-      MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-      MemOp[0] = cast<LoadSDNode>(N1)->getMemOperand();
-      CNode->setMemRefs(MemOp, MemOp + 1);
+      CurDAG->setNodeMemRefs(CNode, {cast<LoadSDNode>(N1)->getMemOperand()});
     } else {
       SDValue Ops[] = { N1, InFlag };
       if (Opc == X86::MULX32rr || Opc == X86::MULX64rr) {
         SDVTList VTs = CurDAG->getVTList(NVT, NVT, MVT::Glue);
         SDNode *CNode = CurDAG->getMachineNode(Opc, dl, VTs, Ops);
         ResHi = SDValue(CNode, 0);
         ResLo = SDValue(CNode, 1);
         InFlag = SDValue(CNode, 2);
if (foldedLoad) {
       SDValue Ops[] = { Tmp0, Tmp1, Tmp2, Tmp3, Tmp4, N1.getOperand(0),
                         InFlag };
       MachineSDNode *CNode =
         CurDAG->getMachineNode(MOpc, dl, MVT::Other, MVT::Glue, Ops);
       InFlag = SDValue(CNode, 1);
       // Update the chain.
       ReplaceUses(N1.getValue(1), SDValue(CNode, 0));
       // Record the mem-refs
-      MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-      MemOp[0] = cast<LoadSDNode>(N1)->getMemOperand();
-      CNode->setMemRefs(MemOp, MemOp + 1);
+      CurDAG->setNodeMemRefs(CNode, {cast<LoadSDNode>(N1)->getMemOperand()});
     } else {
       InFlag =
         SDValue(CurDAG->getMachineNode(Opc, dl, MVT::Glue, N1, InFlag), 0);
     }
 
     // Prevent use of AH in a REX instruction by explicitly copying it to
     // an ABCD_L register.
     //

llvm/lib/Target/X86/X86InstrInfo.cpp

MOs.append(LoadMI.operands_begin() + NumOps - X86::AddrNumOperands,
                LoadMI.operands_begin() + NumOps);
     break;
   }
   }
   return foldMemoryOperandImpl(MF, MI, Ops[0], MOs, InsertPt,
                                /*Size=*/0, Alignment, /*AllowCommute=*/true);
 }
 
+static SmallVector<MachineMemOperand *, 2>
+extractLoadMMOs(ArrayRef<MachineMemOperand *> MMOs, MachineFunction &MF) {
+  SmallVector<MachineMemOperand *, 2> LoadMMOs;
+
+  for (MachineMemOperand *MMO : MMOs) {
+    if (!MMO->isLoad())
+      continue;
+
+    if (!MMO->isStore()) {
+      // Reuse the MMO.
+      LoadMMOs.push_back(MMO);
+    } else {
+      // Clone the MMO and unset the store flag.
+      LoadMMOs.push_back(MF.getMachineMemOperand(
+          MMO->getPointerInfo(), MMO->getFlags() & ~MachineMemOperand::MOStore,
+          MMO->getSize(), MMO->getBaseAlignment(), MMO->getAAInfo(), nullptr,
+          MMO->getSyncScopeID(), MMO->getOrdering(),
+          MMO->getFailureOrdering()));
+    }
+  }
+
+  return LoadMMOs;
+}
+
+static SmallVector<MachineMemOperand *, 2>
+extractStoreMMOs(ArrayRef<MachineMemOperand *> MMOs, MachineFunction &MF) {
+  SmallVector<MachineMemOperand *, 2> StoreMMOs;
+
+  for (MachineMemOperand *MMO : MMOs) {
+    if (!MMO->isStore())
+      continue;
+
+    if (!MMO->isLoad()) {
+      // Reuse the MMO.
+      StoreMMOs.push_back(MMO);
+    } else {
+      // Clone the MMO and unset the load flag.
+      StoreMMOs.push_back(MF.getMachineMemOperand(
+          MMO->getPointerInfo(), MMO->getFlags() & ~MachineMemOperand::MOLoad,
+          MMO->getSize(), MMO->getBaseAlignment(), MMO->getAAInfo(), nullptr,
+          MMO->getSyncScopeID(), MMO->getOrdering(),
+          MMO->getFailureOrdering()));
+    }
+  }
+
+  return StoreMMOs;
+}
+
 bool X86InstrInfo::unfoldMemoryOperand(
     MachineFunction &MF, MachineInstr &MI, unsigned Reg, bool UnfoldLoad,
     bool UnfoldStore, SmallVectorImpl<MachineInstr *> &NewMIs) const {
   const X86MemoryFoldTableEntry *I = lookupUnfoldTable(MI.getOpcode());
   if (I == nullptr)
     return false;
   unsigned Opc = I->DstOp;
   unsigned Index = I->Flags & TB_INDEX_MASK;
X86InstrInfo::unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N,
   }
   SDValue Chain = N->getOperand(NumOps-1);
   AddrOps.push_back(Chain);
 
   // Emit the load instruction.
   SDNode *Load = nullptr;
   if (FoldedLoad) {
     EVT VT = *TRI.legalclasstypes_begin(*RC);
-    std::pair<MachineInstr::mmo_iterator,
-              MachineInstr::mmo_iterator> MMOs =
-      MF.extractLoadMemRefs(cast<MachineSDNode>(N)->memoperands_begin(),
-                            cast<MachineSDNode>(N)->memoperands_end());
-    if (!(*MMOs.first) &&
-        RC == &X86::VR128RegClass &&
+    auto MMOs = extractLoadMMOs(cast<MachineSDNode>(N)->memoperands(), MF);
+    if (MMOs.empty() && RC == &X86::VR128RegClass &&
         Subtarget.isUnalignedMem16Slow())
       // Do not introduce a slow unaligned load.
       return false;
     // FIXME: If a VR128 can have size 32, we should be checking if a 32-byte
     // memory access is slow above.
     unsigned Alignment = std::max<uint32_t>(TRI.getSpillSize(*RC), 16);
-    bool isAligned = (*MMOs.first) &&
-                     (*MMOs.first)->getAlignment() >= Alignment;
+    bool isAligned = !MMOs.empty() && MMOs.front()->getAlignment() >= Alignment;
     Load = DAG.getMachineNode(getLoadRegOpcode(0, RC, isAligned, Subtarget), dl,
                               VT, MVT::Other, AddrOps);
     NewNodes.push_back(Load);
 
     // Preserve memory reference information.
-    cast<MachineSDNode>(Load)->setMemRefs(MMOs.first, MMOs.second);
+    DAG.setNodeMemRefs(cast<MachineSDNode>(Load), MMOs);
   }
 
   // Emit the data processing instruction.
   std::vector<EVT> VTs;
   const TargetRegisterClass *DstRC = nullptr;
   if (MCID.getNumDefs() > 0) {
     DstRC = getRegClass(MCID, 0, &RI, MF);
     VTs.push_back(*TRI.legalclasstypes_begin(*DstRC));
X86InstrInfo::unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N,
   SDNode *NewNode= DAG.getMachineNode(Opc, dl, VTs, BeforeOps);
   NewNodes.push_back(NewNode);
 
   // Emit the store instruction.
   if (FoldedStore) {
     AddrOps.pop_back();
     AddrOps.push_back(SDValue(NewNode, 0));
     AddrOps.push_back(Chain);
-    std::pair<MachineInstr::mmo_iterator,
-              MachineInstr::mmo_iterator> MMOs =
-      MF.extractStoreMemRefs(cast<MachineSDNode>(N)->memoperands_begin(),
-                             cast<MachineSDNode>(N)->memoperands_end());
-    if (!(*MMOs.first) &&
-        RC == &X86::VR128RegClass &&
+    auto MMOs = extractStoreMMOs(cast<MachineSDNode>(N)->memoperands(), MF);
+    if (MMOs.empty() && RC == &X86::VR128RegClass &&
         Subtarget.isUnalignedMem16Slow())
       // Do not introduce a slow unaligned store.
       return false;
     // FIXME: If a VR128 can have size 32, we should be checking if a 32-byte
     // memory access is slow above.
     unsigned Alignment = std::max<uint32_t>(TRI.getSpillSize(*RC), 16);
-    bool isAligned = (*MMOs.first) &&
-                     (*MMOs.first)->getAlignment() >= Alignment;
+    bool isAligned = !MMOs.empty() && MMOs.front()->getAlignment() >= Alignment;
     SDNode *Store =
         DAG.getMachineNode(getStoreRegOpcode(0, DstRC, isAligned, Subtarget),
                            dl, MVT::Other, AddrOps);
     NewNodes.push_back(Store);
 
     // Preserve memory reference information.
-    cast<MachineSDNode>(Store)->setMemRefs(MMOs.first, MMOs.second);
+    DAG.setNodeMemRefs(cast<MachineSDNode>(Store), MMOs);
   }
 
   return true;
 }
 
 unsigned X86InstrInfo::getOpcodeAfterMemoryUnfold(unsigned Opc,
                                       bool UnfoldLoad, bool UnfoldStore,
                                       unsigned *LoadRegIndex) const {

llvm/lib/Target/XCore/XCoreISelDAGToDAG.cpp

case ISD::Constant: {
     }
     else if (!isUInt<16>(Val)) {
       SDValue CPIdx = CurDAG->getTargetConstantPool(
           ConstantInt::get(Type::getInt32Ty(*CurDAG->getContext()), Val),
           getTargetLowering()->getPointerTy(CurDAG->getDataLayout()));
       SDNode *node = CurDAG->getMachineNode(XCore::LDWCP_lru6, dl, MVT::i32,
                                             MVT::Other, CPIdx,
                                             CurDAG->getEntryNode());
-      MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
-      MemOp[0] =
+      MachineMemOperand *MemOp =
           MF->getMachineMemOperand(MachinePointerInfo::getConstantPool(*MF),
                                    MachineMemOperand::MOLoad, 4, 4);
-      cast<MachineSDNode>(node)->setMemRefs(MemOp, MemOp + 1);
+      CurDAG->setNodeMemRefs(cast<MachineSDNode>(node), {MemOp});
       ReplaceNode(N, node);
       return;
     }
     break;
   }
   case XCoreISD::LADD: {
     SDValue Ops[] = { N->getOperand(0), N->getOperand(1),
                         N->getOperand(2) };