[SVE][CodeGen] Add the isTruncatingStore flag to MSCATTER

[kmclaughlin]

Summary

This patch adds the IsTruncatingStore flag to MaskedScatterSDNode, set by getMaskedScatter().
Updated SelectionDAGDumper::print_details for MaskedScatterSDNode to print
the details of masked scatters (is truncating, signed or scaled).

This is the first in a series of patches which adds support for scalable masked scatters

[sdesmalen]

LGTM!

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

2444

nit: in the other functions like DAG.getMaskedScatter, IsTrunc is the last parameter after IndexType. Do you want to do that for the constructor as well for consistency?

[kmclaughlin]

• Made IsTrunc the last parameter to the MaskedScatterSDNode constructor
• Moved changes to SplitVecOp_MSCATTER, which split MemVT before creating the 'Hi' & 'Lo' scatters, into this patch from D90941

[sdesmalen]

Thanks for the changes @kmclaughlin, LGTM.

llvm/include/llvm/CodeGen/SelectionDAG.h

#endif
   SDValue getIndexedMaskedStore(SDValue OrigStore, const SDLoc &dl,
                                 SDValue Base, SDValue Offset,
                                 ISD::MemIndexedMode AM);
   SDValue getMaskedGather(SDVTList VTs, EVT VT, const SDLoc &dl,
                           ArrayRef<SDValue> Ops, MachineMemOperand *MMO,
                           ISD::MemIndexType IndexType);
   SDValue getMaskedScatter(SDVTList VTs, EVT VT, const SDLoc &dl,
                            ArrayRef<SDValue> Ops, MachineMemOperand *MMO,
-                           ISD::MemIndexType IndexType);
+                           ISD::MemIndexType IndexType,
+                           bool IsTruncating = false);
 
   /// Construct a node to track a Value* through the backend.
   SDValue getSrcValue(const Value *v);
 
   /// Return an MDNodeSDNode which holds an MDNode.
   SDValue getMDNode(const MDNode *MD);
 
   /// Return a bitcast using the SDLoc of the value operand, and casting to the

llvm/include/llvm/CodeGen/SelectionDAGNodes.h

class LoadSDNodeBitfields {
 
     uint16_t ExtTy : 2; // enum ISD::LoadExtType
     uint16_t IsExpanding : 1;
   };
 
   class StoreSDNodeBitfields {
     friend class StoreSDNode;
     friend class MaskedStoreSDNode;
+    friend class MaskedScatterSDNode;
 
     uint16_t : NumLSBaseSDNodeBits;
 
     uint16_t IsTruncating : 1;
     uint16_t IsCompressing : 1;
   };
 
   union {

 
 /// This class is used to represent an MSCATTER node
 ///
 class MaskedScatterSDNode : public MaskedGatherScatterSDNode {
 public:
   friend class SelectionDAG;
 
   MaskedScatterSDNode(unsigned Order, const DebugLoc &dl, SDVTList VTs,
-                      EVT MemVT, MachineMemOperand *MMO,
+                      bool IsTrunc, EVT MemVT, MachineMemOperand *MMO,
                       ISD::MemIndexType IndexType)
       : MaskedGatherScatterSDNode(ISD::MSCATTER, Order, dl, VTs, MemVT, MMO,
-                                  IndexType) {}
+                                  IndexType) {
+    StoreSDNodeBits.IsTruncating = IsTrunc;
+  }
+
+  /// Return true if the op does a truncation before store.
+  /// For integers this is the same as doing a TRUNCATE and storing the result.
+  /// For floats, it is the same as doing an FP_ROUND and storing the result.
+  bool isTruncatingStore() const { return StoreSDNodeBits.IsTruncating; }
 
   const SDValue &getValue() const { return getOperand(1); }
 
   static bool classof(const SDNode *N) {
     return N->getOpcode() == ISD::MSCATTER;
   }
 };
 

llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp

SDValue DAGTypeLegalizer::PromoteIntOp_MGATHER(MaskedGatherSDNode *N,
   // Update triggered CSE, do our own replacement since caller can't.
   ReplaceValueWith(SDValue(N, 0), SDValue(Res, 0));
   ReplaceValueWith(SDValue(N, 1), SDValue(Res, 1));
   return SDValue();
 }
 
 SDValue DAGTypeLegalizer::PromoteIntOp_MSCATTER(MaskedScatterSDNode *N,
                                                 unsigned OpNo) {
+  bool TruncateStore = N->isTruncatingStore();
   SmallVector<SDValue, 5> NewOps(N->op_begin(), N->op_end());
   if (OpNo == 2) {
     // The Mask
     EVT DataVT = N->getValue().getValueType();
     NewOps[OpNo] = PromoteTargetBoolean(N->getOperand(OpNo), DataVT);
   } else if (OpNo == 4) {
     // The Index
     if (N->isIndexSigned())
       // Need to sign extend the index since the bits will likely be used.
       NewOps[OpNo] = SExtPromotedInteger(N->getOperand(OpNo));
     else
       NewOps[OpNo] = ZExtPromotedInteger(N->getOperand(OpNo));
-  } else
+
+  } else {
     NewOps[OpNo] = GetPromotedInteger(N->getOperand(OpNo));
-  return SDValue(DAG.UpdateNodeOperands(N, NewOps), 0);
+    TruncateStore = true;
+  }
+
+  return DAG.getMaskedScatter(DAG.getVTList(MVT::Other), N->getMemoryVT(),
+                              SDLoc(N), NewOps, N->getMemOperand(),
+                              N->getIndexType(), TruncateStore);
 }
 
 SDValue DAGTypeLegalizer::PromoteIntOp_TRUNCATE(SDNode *N) {
   SDValue Op = GetPromotedInteger(N->getOperand(0));
   return DAG.getNode(ISD::TRUNCATE, SDLoc(N), N->getValueType(0), Op);
 }
 
 SDValue DAGTypeLegalizer::PromoteIntOp_UINT_TO_FP(SDNode *N) {

llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp

SDValue DAGTypeLegalizer::SplitVecOp_MSCATTER(MaskedScatterSDNode *N,
 
   SDValue Lo;
   MachineMemOperand *MMO = DAG.getMachineFunction().getMachineMemOperand(
       N->getPointerInfo(), MachineMemOperand::MOStore,
       MemoryLocation::UnknownSize, Alignment, N->getAAInfo(), N->getRanges());
 
   SDValue OpsLo[] = {Ch, DataLo, MaskLo, Ptr, IndexLo, Scale};
   Lo = DAG.getMaskedScatter(DAG.getVTList(MVT::Other), DataLo.getValueType(),
-                            DL, OpsLo, MMO, N->getIndexType());
+                            DL, OpsLo, MMO, N->getIndexType(),
+                            N->isTruncatingStore());
 
   // The order of the Scatter operation after split is well defined. The "Hi"
   // part comes after the "Lo". So these two operations should be chained one
   // after another.
   SDValue OpsHi[] = {Lo, DataHi, MaskHi, Ptr, IndexHi, Scale};
   return DAG.getMaskedScatter(DAG.getVTList(MVT::Other), DataHi.getValueType(),
-                              DL, OpsHi, MMO, N->getIndexType());
+                              DL, OpsHi, MMO, N->getIndexType(),
+                              N->isTruncatingStore());
 }
 
 SDValue DAGTypeLegalizer::SplitVecOp_STORE(StoreSDNode *N, unsigned OpNo) {
   assert(N->isUnindexed() && "Indexed store of vector?");
   assert(OpNo == 1 && "Can only split the stored value");
   SDLoc DL(N);
 
   bool isTruncating = N->isTruncatingStore();
if (OpNo == 1) {
     EVT MaskVT = Mask.getValueType();
     EVT WideMaskVT = EVT::getVectorVT(*DAG.getContext(),
                                       MaskVT.getVectorElementType(), NumElts);
     Mask = ModifyToType(Mask, WideMaskVT, true);
   } else if (OpNo == 4) {
     // Just widen the index. It's allowed to have extra elements.
     Index = GetWidenedVector(Index);
   } else
     llvm_unreachable("Can't widen this operand of mscatter");
 
   SDValue Ops[] = {MSC->getChain(), DataOp, Mask, MSC->getBasePtr(), Index,
                    Scale};
   return DAG.getMaskedScatter(DAG.getVTList(MVT::Other),
                               MSC->getMemoryVT(), SDLoc(N), Ops,
-                              MSC->getMemOperand(), MSC->getIndexType());
+                              MSC->getMemOperand(), MSC->getIndexType(),
+                              MSC->isTruncatingStore());
 }
 
 SDValue DAGTypeLegalizer::WidenVecOp_SETCC(SDNode *N) {
   SDValue InOp0 = GetWidenedVector(N->getOperand(0));
   SDValue InOp1 = GetWidenedVector(N->getOperand(1));
   SDLoc dl(N);
   EVT VT = N->getValueType(0);
 

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

SDValue SelectionDAG::getMaskedGather(SDVTList VTs, EVT VT, const SDLoc &dl,
   SDValue V(N, 0);
   NewSDValueDbgMsg(V, "Creating new node: ", this);
   return V;
 }
 
 SDValue SelectionDAG::getMaskedScatter(SDVTList VTs, EVT VT, const SDLoc &dl,
                                        ArrayRef<SDValue> Ops,
                                        MachineMemOperand *MMO,
-                                       ISD::MemIndexType IndexType) {
+                                       ISD::MemIndexType IndexType,
+                                       bool IsTrunc) {
   assert(Ops.size() == 6 && "Incompatible number of operands");
 
   FoldingSetNodeID ID;
   AddNodeIDNode(ID, ISD::MSCATTER, VTs, Ops);
   ID.AddInteger(VT.getRawBits());
   ID.AddInteger(getSyntheticNodeSubclassData<MaskedScatterSDNode>(
-      dl.getIROrder(), VTs, VT, MMO, IndexType));
+      dl.getIROrder(), VTs, IsTrunc, VT, MMO, IndexType));
   ID.AddInteger(MMO->getPointerInfo().getAddrSpace());
   void *IP = nullptr;
   if (SDNode *E = FindNodeOrInsertPos(ID, dl, IP)) {
     cast<MaskedScatterSDNode>(E)->refineAlignment(MMO);
     return SDValue(E, 0);
   }
+
   auto *N = newSDNode<MaskedScatterSDNode>(dl.getIROrder(), dl.getDebugLoc(),
-                                           VTs, VT, MMO, IndexType);
+                                           VTs, IsTrunc, VT, MMO, IndexType);
   createOperands(N, Ops);
 
   assert(N->getMask().getValueType().getVectorNumElements() ==
              N->getValue().getValueType().getVectorNumElements() &&
          "Vector width mismatch between mask and data");
   assert(N->getIndex().getValueType().getVectorNumElements() >=
              N->getValue().getValueType().getVectorNumElements() &&
          "Vector width mismatch between index and data");

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

void SelectionDAGBuilder::visitMaskedScatter(const CallInst &I) {
   if (!UniformBase) {
     Base = DAG.getConstant(0, sdl, TLI.getPointerTy(DAG.getDataLayout()));
     Index = getValue(Ptr);
     IndexType = ISD::SIGNED_SCALED;
     Scale = DAG.getTargetConstant(1, sdl, TLI.getPointerTy(DAG.getDataLayout()));
   }
   SDValue Ops[] = { getMemoryRoot(), Src0, Mask, Base, Index, Scale };
   SDValue Scatter = DAG.getMaskedScatter(DAG.getVTList(MVT::Other), VT, sdl,
-                                         Ops, MMO, IndexType);
+                                         Ops, MMO, IndexType, false);
   DAG.setRoot(Scatter);
   setValue(&I, Scatter);
 }
 
 void SelectionDAGBuilder::visitMaskedLoad(const CallInst &I, bool IsExpanding) {
   SDLoc sdl = getCurSDLoc();
 
   auto getMaskedLoadOps = [&](Value *&Ptr, Value *&Mask, Value *&Src0,

llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp

else if (const LoadSDNode *LD = dyn_cast<LoadSDNode>(this)) {
     const char *AM = getIndexedModeName(MSt->getAddressingMode());
     if (*AM)
       OS << ", " << AM;
 
     if (MSt->isCompressingStore())
       OS << ", compressing";
 
     OS << ">";
-  } else if (const MemSDNode* M = dyn_cast<MemSDNode>(this)) {
+  } else if (const auto *MScatter = dyn_cast<MaskedScatterSDNode>(this)) {
+    OS << "<";
+    printMemOperand(OS, *MScatter->getMemOperand(), G);
+
+    if (MScatter->isTruncatingStore())
+      OS << ", trunc to " << MScatter->getMemoryVT().getEVTString();
+
+    auto Signed = MScatter->isIndexSigned() ? "signed" : "unsigned";
+    auto Scaled = MScatter->isIndexScaled() ? "scaled" : "unscaled";
+    OS << ", " << Signed << " " << Scaled << " offset";
+
+    OS << ">";
+  } else if (const MemSDNode *M = dyn_cast<MemSDNode>(this)) {
     OS << "<";
     printMemOperand(OS, *M->getMemOperand(), G);
     OS << ">";
   } else if (const BlockAddressSDNode *BA =
                dyn_cast<BlockAddressSDNode>(this)) {
     int64_t offset = BA->getOffset();
     OS << "<";
     BA->getBlockAddress()->getFunction()->printAsOperand(OS, false);
     OS << ", ";
     BA->getBlockAddress()->getBasicBlock()->printAsOperand(OS, false);
     OS << ">";
     if (offset > 0)
       OS << " + " << offset;
     else
       OS << " " << offset;
     if (unsigned int TF = BA->getTargetFlags())
       OS << " [TF=" << TF << ']';
   } else if (const AddrSpaceCastSDNode *ASC =
                dyn_cast<AddrSpaceCastSDNode>(this)) {
     OS << '['
        << ASC->getSrcAddressSpace()
        << " -> "
        << ASC->getDestAddressSpace()
        << ']';
   } else if (const LifetimeSDNode *LN = dyn_cast<LifetimeSDNode>(this)) {
     if (LN->hasOffset())
       OS << "<" << LN->getOffset() << " to " << LN->getOffset() + LN->getSize() << ">";

llvm/lib/Target/X86/X86ISelLowering.cpp

if (auto *Gather = dyn_cast<MaskedGatherSDNode>(GorS)) {
     return DAG.getMaskedGather(Gather->getVTList(),
                                Gather->getMemoryVT(), DL, Ops,
                                Gather->getMemOperand(),
                                Gather->getIndexType());
   }
   auto *Scatter = cast<MaskedScatterSDNode>(GorS);
   SDValue Ops[] = { Scatter->getChain(), Scatter->getValue(),
                     Scatter->getMask(), Base, Index, Scale };
   return DAG.getMaskedScatter(Scatter->getVTList(),
                               Scatter->getMemoryVT(), DL,
                               Ops, Scatter->getMemOperand(),
-                              Scatter->getIndexType());
+                              Scatter->getIndexType(),
+                              Scatter->isTruncatingStore());
 }
 
 static SDValue combineGatherScatter(SDNode *N, SelectionDAG &DAG,
                                     TargetLowering::DAGCombinerInfo &DCI) {
   SDLoc DL(N);
   auto *GorS = cast<MaskedGatherScatterSDNode>(N);
   SDValue Index = GorS->getIndex();
   SDValue Base = GorS->getBasePtr();