[SVE][LegalizeTypes] Support widen/split legalization for SPLAT_VECTOR

[efriedma]

Summary

Just the obvious implementation that rewrites the result type. Also fix warning from EXTRACT_SUBVECTOR legalization that triggers on the test.

llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h

private:
   void SplitVecRes_EXTRACT_SUBVECTOR(SDNode *N, SDValue &Lo, SDValue &Hi);
   void SplitVecRes_INSERT_SUBVECTOR(SDNode *N, SDValue &Lo, SDValue &Hi);
   void SplitVecRes_FPOWI(SDNode *N, SDValue &Lo, SDValue &Hi);
   void SplitVecRes_FCOPYSIGN(SDNode *N, SDValue &Lo, SDValue &Hi);
   void SplitVecRes_INSERT_VECTOR_ELT(SDNode *N, SDValue &Lo, SDValue &Hi);
   void SplitVecRes_LOAD(LoadSDNode *LD, SDValue &Lo, SDValue &Hi);
   void SplitVecRes_MLOAD(MaskedLoadSDNode *MLD, SDValue &Lo, SDValue &Hi);
   void SplitVecRes_MGATHER(MaskedGatherSDNode *MGT, SDValue &Lo, SDValue &Hi);
-  void SplitVecRes_SCALAR_TO_VECTOR(SDNode *N, SDValue &Lo, SDValue &Hi);
+  void SplitVecRes_ScalarOp(SDNode *N, SDValue &Lo, SDValue &Hi);
   void SplitVecRes_SETCC(SDNode *N, SDValue &Lo, SDValue &Hi);
   void SplitVecRes_VECTOR_SHUFFLE(ShuffleVectorSDNode *N, SDValue &Lo,
                                   SDValue &Hi);
   void SplitVecRes_VAARG(SDNode *N, SDValue &Lo, SDValue &Hi);
 
   // Vector Operand Splitting: <128 x ty> -> 2 x <64 x ty>.
   bool SplitVectorOperand(SDNode *N, unsigned OpNo);
   SDValue SplitVecOp_VSELECT(SDNode *N, unsigned OpNo);
private:
   SDValue WidenVecRes_BUILD_VECTOR(SDNode* N);
   SDValue WidenVecRes_CONCAT_VECTORS(SDNode* N);
   SDValue WidenVecRes_EXTEND_VECTOR_INREG(SDNode* N);
   SDValue WidenVecRes_EXTRACT_SUBVECTOR(SDNode* N);
   SDValue WidenVecRes_INSERT_VECTOR_ELT(SDNode* N);
   SDValue WidenVecRes_LOAD(SDNode* N);
   SDValue WidenVecRes_MLOAD(MaskedLoadSDNode* N);
   SDValue WidenVecRes_MGATHER(MaskedGatherSDNode* N);
-  SDValue WidenVecRes_SCALAR_TO_VECTOR(SDNode* N);
+  SDValue WidenVecRes_ScalarOp(SDNode* N);
   SDValue WidenVecRes_SELECT(SDNode* N);
   SDValue WidenVSELECTAndMask(SDNode *N);
   SDValue WidenVecRes_SELECT_CC(SDNode* N);
   SDValue WidenVecRes_SETCC(SDNode* N);
   SDValue WidenVecRes_STRICT_FSETCC(SDNode* N);
   SDValue WidenVecRes_UNDEF(SDNode *N);
   SDValue WidenVecRes_VECTOR_SHUFFLE(ShuffleVectorSDNode *N);
 

llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp

#endif
   case ISD::BITCAST:           SplitVecRes_BITCAST(N, Lo, Hi); break;
   case ISD::BUILD_VECTOR:      SplitVecRes_BUILD_VECTOR(N, Lo, Hi); break;
   case ISD::CONCAT_VECTORS:    SplitVecRes_CONCAT_VECTORS(N, Lo, Hi); break;
   case ISD::EXTRACT_SUBVECTOR: SplitVecRes_EXTRACT_SUBVECTOR(N, Lo, Hi); break;
   case ISD::INSERT_SUBVECTOR:  SplitVecRes_INSERT_SUBVECTOR(N, Lo, Hi); break;
   case ISD::FPOWI:             SplitVecRes_FPOWI(N, Lo, Hi); break;
   case ISD::FCOPYSIGN:         SplitVecRes_FCOPYSIGN(N, Lo, Hi); break;
   case ISD::INSERT_VECTOR_ELT: SplitVecRes_INSERT_VECTOR_ELT(N, Lo, Hi); break;
-  case ISD::SCALAR_TO_VECTOR:  SplitVecRes_SCALAR_TO_VECTOR(N, Lo, Hi); break;
+  case ISD::SPLAT_VECTOR:
+  case ISD::SCALAR_TO_VECTOR:
+    SplitVecRes_ScalarOp(N, Lo, Hi);
+    break;
   case ISD::SIGN_EXTEND_INREG: SplitVecRes_InregOp(N, Lo, Hi); break;
   case ISD::LOAD:
     SplitVecRes_LOAD(cast<LoadSDNode>(N), Lo, Hi);
     break;
   case ISD::MLOAD:
     SplitVecRes_MLOAD(cast<MaskedLoadSDNode>(N), Lo, Hi);
     break;
   case ISD::MGATHER:
void DAGTypeLegalizer::SplitVecRes_INSERT_VECTOR_ELT(SDNode *N, SDValue &Lo,
   // If we adjusted the original type, we need to truncate the results.
   std::tie(LoVT, HiVT) = DAG.GetSplitDestVTs(N->getValueType(0));
   if (LoVT != Lo.getValueType())
     Lo = DAG.getNode(ISD::TRUNCATE, dl, LoVT, Lo);
   if (HiVT != Hi.getValueType())
     Hi = DAG.getNode(ISD::TRUNCATE, dl, HiVT, Hi);
 }
 
-void DAGTypeLegalizer::SplitVecRes_SCALAR_TO_VECTOR(SDNode *N, SDValue &Lo,
-                                                    SDValue &Hi) {
+void DAGTypeLegalizer::SplitVecRes_ScalarOp(SDNode *N, SDValue &Lo,
   EVT LoVT, HiVT;
   SDLoc dl(N);
   std::tie(LoVT, HiVT) = DAG.GetSplitDestVTs(N->getValueType(0));
-  Lo = DAG.getNode(ISD::SCALAR_TO_VECTOR, dl, LoVT, N->getOperand(0));
+  Lo = DAG.getNode(N->getOpcode(), dl, LoVT, N->getOperand(0));
+  if (N->getOpcode() == ISD::SCALAR_TO_VECTOR) {
     Hi = DAG.getUNDEF(HiVT);
+  } else {
+    assert(N->getOpcode() == ISD::SPLAT_VECTOR && "Unexpected opcode");
+    Hi = Lo;
+  }
 }
 
 void DAGTypeLegalizer::SplitVecRes_LOAD(LoadSDNode *LD, SDValue &Lo,
                                         SDValue &Hi) {
   assert(ISD::isUNINDEXEDLoad(LD) && "Indexed load during type legalization!");
   EVT LoVT, HiVT;
   SDLoc dl(LD);
   std::tie(LoVT, HiVT) = DAG.GetSplitDestVTs(LD->getValueType(0));
SDValue DAGTypeLegalizer::SplitVecOp_BITCAST(SDNode *N) {
 
   return DAG.getNode(ISD::BITCAST, SDLoc(N), N->getValueType(0),
                      JoinIntegers(Lo, Hi));
 }
 
 SDValue DAGTypeLegalizer::SplitVecOp_EXTRACT_SUBVECTOR(SDNode *N) {
   // We know that the extracted result type is legal.
   EVT SubVT = N->getValueType(0);
+
+  if (SubVT.isScalableVector() !=
+      N->getOperand(0).getValueType().isScalableVector())
+    report_fatal_error("Extracting fixed from scalable not implemented");
+
   SDValue Idx = N->getOperand(1);
   SDLoc dl(N);
   SDValue Lo, Hi;
 
   if (SubVT.isScalableVector() !=
       N->getOperand(0).getValueType().isScalableVector())
     report_fatal_error("Extracting a fixed-length vector from an illegal "
                        "scalable vector is not yet supported");
#endif
 
   case ISD::MERGE_VALUES:      Res = WidenVecRes_MERGE_VALUES(N, ResNo); break;
   case ISD::BITCAST:           Res = WidenVecRes_BITCAST(N); break;
   case ISD::BUILD_VECTOR:      Res = WidenVecRes_BUILD_VECTOR(N); break;
   case ISD::CONCAT_VECTORS:    Res = WidenVecRes_CONCAT_VECTORS(N); break;
   case ISD::EXTRACT_SUBVECTOR: Res = WidenVecRes_EXTRACT_SUBVECTOR(N); break;
   case ISD::INSERT_VECTOR_ELT: Res = WidenVecRes_INSERT_VECTOR_ELT(N); break;
   case ISD::LOAD:              Res = WidenVecRes_LOAD(N); break;
-  case ISD::SCALAR_TO_VECTOR:  Res = WidenVecRes_SCALAR_TO_VECTOR(N); break;
+  case ISD::SPLAT_VECTOR:
+  case ISD::SCALAR_TO_VECTOR:
+    Res = WidenVecRes_ScalarOp(N);
+    break;
   case ISD::SIGN_EXTEND_INREG: Res = WidenVecRes_InregOp(N); break;
   case ISD::VSELECT:
   case ISD::SELECT:            Res = WidenVecRes_SELECT(N); break;
   case ISD::SELECT_CC:         Res = WidenVecRes_SELECT_CC(N); break;
   case ISD::SETCC:             Res = WidenVecRes_SETCC(N); break;
   case ISD::UNDEF:             Res = WidenVecRes_UNDEF(N); break;
   case ISD::VECTOR_SHUFFLE:
     Res = WidenVecRes_VECTOR_SHUFFLE(cast<ShuffleVectorSDNode>(N));
SDValue Res = DAG.getMaskedGather(DAG.getVTList(WideVT, MVT::Other),
                                     N->getMemOperand(), N->getIndexType());
 
   // Legalize the chain result - switch anything that used the old chain to
   // use the new one.
   ReplaceValueWith(SDValue(N, 1), Res.getValue(1));
   return Res;
 }
 
-SDValue DAGTypeLegalizer::WidenVecRes_SCALAR_TO_VECTOR(SDNode *N) {
+SDValue DAGTypeLegalizer::WidenVecRes_ScalarOp(SDNode *N) {
   EVT WidenVT = TLI.getTypeToTransformTo(*DAG.getContext(), N->getValueType(0));
-  return DAG.getNode(ISD::SCALAR_TO_VECTOR, SDLoc(N),
-                     WidenVT, N->getOperand(0));
+  return DAG.getNode(N->getOpcode(), SDLoc(N), WidenVT, N->getOperand(0));
 }
 
 // Return true is this is a SETCC node or a strict version of it.
 static inline bool isSETCCOp(unsigned Opcode) {
   switch (Opcode) {
   case ISD::SETCC:
   case ISD::STRICT_FSETCC:
   case ISD::STRICT_FSETCCS:

llvm/test/CodeGen/AArch64/sve-vector-splat.ll

 ; CHECK-LABEL: @sve_splat_2xi32
 ; CHECK: mov z0.d, x0
 ; CHECK-NEXT: ret
   %ins = insertelement <vscale x 2 x i32> undef, i32 %val, i32 0
   %splat = shufflevector <vscale x 2 x i32> %ins, <vscale x 2 x i32> undef, <vscale x 2 x i32> zeroinitializer
   ret <vscale x 2 x i32> %splat
 }
 
+;; Widen/split splats of wide vector types.
+
+define <vscale x 12 x i32> @sve_splat_12xi32(i32 %val) {
+; CHECK-LABEL: @sve_splat_12xi32
+; CHECK: mov z0.s, w0
+; CHECK-NEXT: mov z1.d, z0.d
+; CHECK-NEXT: mov z2.d, z0.d
+; CHECK-NEXT: ret
+  %ins = insertelement <vscale x 12 x i32> undef, i32 %val, i32 0
+  %splat = shufflevector <vscale x 12 x i32> %ins, <vscale x 12 x i32> undef, <vscale x 12 x i32> zeroinitializer
+  ret <vscale x 12 x i32> %splat
+}
+
 define <vscale x 2 x i1> @sve_splat_2xi1(i1 %val) {
 ; CHECK-LABEL: @sve_splat_2xi1
 ; CHECK: sbfx x8, x0, #0, #1
 ; CHECK-NEXT: whilelo p0.d, xzr, x8
 ; CHECK-NEXT: ret
   %ins = insertelement <vscale x 2 x i1> undef, i1 %val, i32 0
   %splat = shufflevector <vscale x 2 x i1> %ins, <vscale x 2 x i1> undef, <vscale x 2 x i32> zeroinitializer
   ret <vscale x 2 x i1> %splat