Do not legalize large setcc with setcce, introduce setcccarry and do it with usubo/setcccarry.

[deadalnix]

Summary

This is a continuation of the work started in D29872 . Passing the carry down as a value rather than as a glue allows for further optimizations. Introducing setcccarry makes the use of addc/subc unecessary and we can start the removal process.

This patch only introduce the optimization strictly required to get the same level of optimization as was available before nothing more.

[RKSimon]

Can you remove ISD::SETCCE x86 lowering completely as part of this patch?

test/CodeGen/X86/wide-integer-cmp.ll

4

Why?

[deadalnix]

I'd rather remove it as part of D33390 than this one. Just in case something goes wrong, it'll be easier to revert.

test/CodeGen/X86/wide-integer-cmp.ll

4

Just leftovers. I'll remove.

[RKSimon]

What is your plan for the ARM/Lanai ISD::SETCCE support? That's all that is stopping its removal.

[deadalnix]

I don't have a specific plan except it needs to be done and I got to figure out how to do it :)

[deadalnix]

Use getOperationAction as isOperationLegalOrCustom is breaking the AMDGPU backend for some reason. Remove formating change in wide-integer-cmp.ll .

[RKSimon]

In D33374#765756, @deadalnix wrote:

I don't have a specific plan except it needs to be done and I got to figure out how to do it :)

Would it be possible to include the ARM/Lanai changes in this patch?

[deadalnix]

@RKSimon I don't think it fit the scope of this diff. Plus I'm not that familiar with these backends, so it'll take time and gate other work.

[RKSimon]

lib/Target/X86/X86ISelLowering.cpp

34502

I'm curious why you're dropping ISD::SETCC support here - is the change independent of the rest of the patch?

[deadalnix]

lib/Target/X86/X86ISelLowering.cpp

34502

It never worked and is invalid. It could indeed be part of another diff.

[RKSimon]

LGTM - thanks.

lib/Target/X86/X86ISelLowering.cpp

34502

OK, please commit this as a separate pre-commit, it doesn't need review.

[deadalnix]

Remove setcc change in combineX86ADD .

include/llvm/CodeGen/ISDOpcodes.h

enum NodeType {
     /// them with (op #2) as a CondCodeSDNode. If the operands are vector types
     /// then the result type must also be a vector type.
     SETCC,
 
     /// Like SetCC, ops #0 and #1 are the LHS and RHS operands to compare, but
     /// op #2 is a *carry value*. This operator checks the result of
     /// "LHS - RHS - Carry", and can be used to compare two wide integers:
     /// (setcce lhshi rhshi (subc lhslo rhslo) cc). Only valid for integers.
+    /// FIXME: This node is deprecated in favor of SETCCCARRY.
+    /// It is kept around for now to provide a smooth transition path
+    /// toward the use of SETCCCARRY and will eventually be removed.
     SETCCE,
 
+    /// Like SetCC, ops #0 and #1 are the LHS and RHS operands to compare, but
+    /// op #2 is a boolean indicating if there is an incoming carry. This
+    /// operator checks the result of "LHS - RHS - Carry", and can be used to
+    /// compare two wide integers: (setcce lhshi rhshi (subc lhslo rhslo) cc).
+    /// Only valid for integers.
+    SETCCCARRY,
+
     /// SHL_PARTS/SRA_PARTS/SRL_PARTS - These operators are used for expanded
     /// integer shift operations.  The operation ordering is:
     ///       [Lo,Hi] = op [LoLHS,HiLHS], Amt
     SHL_PARTS, SRA_PARTS, SRL_PARTS,
 
     /// Conversion operators.  These are all single input single output
     /// operations.  For all of these, the result type must be strictly
     /// wider or narrower (depending on the operation) than the source

lib/CodeGen/SelectionDAG/DAGCombiner.cpp

private:
     SDValue visitCTTZ(SDNode *N);
     SDValue visitCTTZ_ZERO_UNDEF(SDNode *N);
     SDValue visitCTPOP(SDNode *N);
     SDValue visitSELECT(SDNode *N);
     SDValue visitVSELECT(SDNode *N);
     SDValue visitSELECT_CC(SDNode *N);
     SDValue visitSETCC(SDNode *N);
     SDValue visitSETCCE(SDNode *N);
+    SDValue visitSETCCCARRY(SDNode *N);
     SDValue visitSIGN_EXTEND(SDNode *N);
     SDValue visitZERO_EXTEND(SDNode *N);
     SDValue visitANY_EXTEND(SDNode *N);
     SDValue visitAssertZext(SDNode *N);
     SDValue visitSIGN_EXTEND_INREG(SDNode *N);
     SDValue visitSIGN_EXTEND_VECTOR_INREG(SDNode *N);
     SDValue visitZERO_EXTEND_VECTOR_INREG(SDNode *N);
     SDValue visitTRUNCATE(SDNode *N);
SDValue DAGCombiner::visit(SDNode *N) {
   case ISD::CTTZ:               return visitCTTZ(N);
   case ISD::CTTZ_ZERO_UNDEF:    return visitCTTZ_ZERO_UNDEF(N);
   case ISD::CTPOP:              return visitCTPOP(N);
   case ISD::SELECT:             return visitSELECT(N);
   case ISD::VSELECT:            return visitVSELECT(N);
   case ISD::SELECT_CC:          return visitSELECT_CC(N);
   case ISD::SETCC:              return visitSETCC(N);
   case ISD::SETCCE:             return visitSETCCE(N);
+  case ISD::SETCCCARRY:         return visitSETCCCARRY(N);
   case ISD::SIGN_EXTEND:        return visitSIGN_EXTEND(N);
   case ISD::ZERO_EXTEND:        return visitZERO_EXTEND(N);
   case ISD::ANY_EXTEND:         return visitANY_EXTEND(N);
   case ISD::AssertZext:         return visitAssertZext(N);
   case ISD::SIGN_EXTEND_INREG:  return visitSIGN_EXTEND_INREG(N);
   case ISD::SIGN_EXTEND_VECTOR_INREG: return visitSIGN_EXTEND_VECTOR_INREG(N);
   case ISD::ZERO_EXTEND_VECTOR_INREG: return visitZERO_EXTEND_VECTOR_INREG(N);
   case ISD::TRUNCATE:           return visitTRUNCATE(N);
SDValue DAGCombiner::visitSETCCE(SDNode *N) {
 
   // If Carry is false, fold to a regular SETCC.
   if (Carry.getOpcode() == ISD::CARRY_FALSE)
     return DAG.getNode(ISD::SETCC, SDLoc(N), N->getVTList(), LHS, RHS, Cond);
 
   return SDValue();
 }
 
+SDValue DAGCombiner::visitSETCCCARRY(SDNode *N) {
+  SDValue LHS = N->getOperand(0);
+  SDValue RHS = N->getOperand(1);
+  SDValue Carry = N->getOperand(2);
+  SDValue Cond = N->getOperand(3);
+
+  // If Carry is false, fold to a regular SETCC.
+  if (isNullConstant(Carry))
+    return DAG.getNode(ISD::SETCC, SDLoc(N), N->getVTList(), LHS, RHS, Cond);
+
+  return SDValue();
+}
+
 /// Try to fold a sext/zext/aext dag node into a ConstantSDNode or
 /// a build_vector of constants.
 /// This function is called by the DAGCombiner when visiting sext/zext/aext
 /// dag nodes (see for example method DAGCombiner::visitSIGN_EXTEND).
 /// Vector extends are not folded if operations are legal; this is to
 /// avoid introducing illegal build_vector dag nodes.
 static SDNode *tryToFoldExtendOfConstant(SDNode *N, const TargetLowering &TLI,
                                          SelectionDAG &DAG, bool LegalTypes,

lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp

bool DAGTypeLegalizer::ExpandIntegerOperand(SDNode *N, unsigned OpNo) {
   case ISD::BR_CC:             Res = ExpandIntOp_BR_CC(N); break;
   case ISD::BUILD_VECTOR:      Res = ExpandOp_BUILD_VECTOR(N); break;
   case ISD::EXTRACT_ELEMENT:   Res = ExpandOp_EXTRACT_ELEMENT(N); break;
   case ISD::INSERT_VECTOR_ELT: Res = ExpandOp_INSERT_VECTOR_ELT(N); break;
   case ISD::SCALAR_TO_VECTOR:  Res = ExpandOp_SCALAR_TO_VECTOR(N); break;
   case ISD::SELECT_CC:         Res = ExpandIntOp_SELECT_CC(N); break;
   case ISD::SETCC:             Res = ExpandIntOp_SETCC(N); break;
   case ISD::SETCCE:            Res = ExpandIntOp_SETCCE(N); break;
+  case ISD::SETCCCARRY:        Res = ExpandIntOp_SETCCCARRY(N); break;
   case ISD::SINT_TO_FP:        Res = ExpandIntOp_SINT_TO_FP(N); break;
   case ISD::STORE:   Res = ExpandIntOp_STORE(cast<StoreSDNode>(N), OpNo); break;
   case ISD::TRUNCATE:          Res = ExpandIntOp_TRUNCATE(N); break;
   case ISD::UINT_TO_FP:        Res = ExpandIntOp_UINT_TO_FP(N); break;
 
   case ISD::SHL:
   case ISD::SRA:
   case ISD::SRL:
void DAGTypeLegalizer::IntegerExpandSetCCOperands(SDValue &NewLHS,
 
   if (LHSHi == RHSHi) {
     // Comparing the low bits is enough.
     NewLHS = LoCmp;
     NewRHS = SDValue();
     return;
   }
 
-  // Lower with SETCCE if the target supports it.
+  // Lower with SETCCE or SETCCCARRY if the target supports it.
+  EVT HiVT = LHSHi.getValueType();
+  EVT ExpandVT = TLI.getTypeToExpandTo(*DAG.getContext(), HiVT);
+  bool HasSETCCCARRY = TLI.isOperationLegalOrCustom(ISD::SETCCCARRY, ExpandVT);
+
   // FIXME: Make all targets support this, then remove the other lowering.
-  if (TLI.getOperationAction(
-          ISD::SETCCE,
-          TLI.getTypeToExpandTo(*DAG.getContext(), LHSLo.getValueType())) ==
-      TargetLowering::Custom) {
-    // SETCCE can detect < and >= directly. For > and <=, flip operands and
-    // condition code.
+  if (HasSETCCCARRY || TLI.isOperationLegalOrCustom(ISD::SETCCE, ExpandVT)) {
+    // SETCCE/SETCCCARRY can detect < and >= directly. For > and <=, flip
+    // operands and condition code.
     bool FlipOperands = false;
     switch (CCCode) {
     case ISD::SETGT:  CCCode = ISD::SETLT;  FlipOperands = true; break;
     case ISD::SETUGT: CCCode = ISD::SETULT; FlipOperands = true; break;
     case ISD::SETLE:  CCCode = ISD::SETGE;  FlipOperands = true; break;
     case ISD::SETULE: CCCode = ISD::SETUGE; FlipOperands = true; break;
     default: break;
     }
     if (FlipOperands) {
       std::swap(LHSLo, RHSLo);
       std::swap(LHSHi, RHSHi);
     }
     // Perform a wide subtraction, feeding the carry from the low part into
-    // SETCCE. The SETCCE operation is essentially looking at the high part of
-    // the result of LHS - RHS. It is negative iff LHS < RHS. It is zero or
-    // positive iff LHS >= RHS.
-    SDVTList VTList = DAG.getVTList(LHSLo.getValueType(), MVT::Glue);
-    SDValue LowCmp = DAG.getNode(ISD::SUBC, dl, VTList, LHSLo, RHSLo);
-    SDValue Res =
-        DAG.getNode(ISD::SETCCE, dl, getSetCCResultType(LHSLo.getValueType()),
-                    LHSHi, RHSHi, LowCmp.getValue(1), DAG.getCondCode(CCCode));
+    // SETCCE/SETCCCARRY. The SETCCE/SETCCCARRY operation is essentially
+    // looking at the high part of the result of LHS - RHS. It is negative
+    // iff LHS < RHS. It is zero or positive iff LHS >= RHS.
+    EVT LoVT = LHSLo.getValueType();
+    SDVTList VTList = DAG.getVTList(
+        LoVT, HasSETCCCARRY ? getSetCCResultType(LoVT) : MVT::Glue);
+    SDValue LowCmp = DAG.getNode(HasSETCCCARRY ? ISD::USUBO : ISD::SUBC, dl,
+                                 VTList, LHSLo, RHSLo);
+    SDValue Res = DAG.getNode(HasSETCCCARRY ? ISD::SETCCCARRY : ISD::SETCCE, dl,
+                              getSetCCResultType(HiVT), LHSHi, RHSHi,
+                              LowCmp.getValue(1), DAG.getCondCode(CCCode));
     NewLHS = Res;
     NewRHS = SDValue();
     return;
   }
 
-  NewLHS = TLI.SimplifySetCC(getSetCCResultType(LHSHi.getValueType()),
-                             LHSHi, RHSHi, ISD::SETEQ, false,
-                             DagCombineInfo, dl);
+  NewLHS = TLI.SimplifySetCC(getSetCCResultType(HiVT), LHSHi, RHSHi, ISD::SETEQ,
+                             false, DagCombineInfo, dl);
   if (!NewLHS.getNode())
-    NewLHS = DAG.getSetCC(dl, getSetCCResultType(LHSHi.getValueType()),
-                          LHSHi, RHSHi, ISD::SETEQ);
-  NewLHS = DAG.getSelect(dl, LoCmp.getValueType(),
-                         NewLHS, LoCmp, HiCmp);
+    NewLHS =
+        DAG.getSetCC(dl, getSetCCResultType(HiVT), LHSHi, RHSHi, ISD::SETEQ);
+  NewLHS = DAG.getSelect(dl, LoCmp.getValueType(), NewLHS, LoCmp, HiCmp);
   NewRHS = SDValue();
 }
 
 SDValue DAGTypeLegalizer::ExpandIntOp_BR_CC(SDNode *N) {
   SDValue NewLHS = N->getOperand(2), NewRHS = N->getOperand(3);
   ISD::CondCode CCCode = cast<CondCodeSDNode>(N->getOperand(1))->get();
   IntegerExpandSetCCOperands(NewLHS, NewRHS, CCCode, SDLoc(N));
 
SDValue DAGTypeLegalizer::ExpandIntOp_SETCC(SDNode *N) {
   // If ExpandSetCCOperands returned a scalar, use it.
   if (!NewRHS.getNode()) {
     assert(NewLHS.getValueType() == N->getValueType(0) &&
            "Unexpected setcc expansion!");
     return NewLHS;
   }
 
   // Otherwise, update N to have the operands specified.
-  return SDValue(DAG.UpdateNodeOperands(N, NewLHS, NewRHS,
-                                DAG.getCondCode(CCCode)), 0);
+  return SDValue(
+      DAG.UpdateNodeOperands(N, NewLHS, NewRHS, DAG.getCondCode(CCCode)), 0);
 }
 
 SDValue DAGTypeLegalizer::ExpandIntOp_SETCCE(SDNode *N) {
   SDValue LHS = N->getOperand(0);
   SDValue RHS = N->getOperand(1);
   SDValue Carry = N->getOperand(2);
   SDValue Cond = N->getOperand(3);
   SDLoc dl = SDLoc(N);
 
   SDValue LHSLo, LHSHi, RHSLo, RHSHi;
   GetExpandedInteger(LHS, LHSLo, LHSHi);
   GetExpandedInteger(RHS, RHSLo, RHSHi);
 
   // Expand to a SUBE for the low part and a smaller SETCCE for the high.
   SDVTList VTList = DAG.getVTList(LHSLo.getValueType(), MVT::Glue);
   SDValue LowCmp = DAG.getNode(ISD::SUBE, dl, VTList, LHSLo, RHSLo, Carry);
   return DAG.getNode(ISD::SETCCE, dl, N->getValueType(0), LHSHi, RHSHi,
                      LowCmp.getValue(1), Cond);
 }
 
+SDValue DAGTypeLegalizer::ExpandIntOp_SETCCCARRY(SDNode *N) {
+  SDValue LHS = N->getOperand(0);
+  SDValue RHS = N->getOperand(1);
+  SDValue Carry = N->getOperand(2);
+  SDValue Cond = N->getOperand(3);
+  SDLoc dl = SDLoc(N);
+
+  SDValue LHSLo, LHSHi, RHSLo, RHSHi;
+  GetExpandedInteger(LHS, LHSLo, LHSHi);
+  GetExpandedInteger(RHS, RHSLo, RHSHi);
+
+  // Expand to a SUBE for the low part and a smaller SETCCCARRY for the high.
+  SDVTList VTList = DAG.getVTList(LHSLo.getValueType(), Carry.getValueType());
+  SDValue LowCmp = DAG.getNode(ISD::SUBCARRY, dl, VTList, LHSLo, RHSLo, Carry);
+  return DAG.getNode(ISD::SETCCCARRY, dl, N->getValueType(0), LHSHi, RHSHi,
+                     LowCmp.getValue(1), Cond);
+}
+
 SDValue DAGTypeLegalizer::ExpandIntOp_Shift(SDNode *N) {
   // The value being shifted is legal, but the shift amount is too big.
   // It follows that either the result of the shift is undefined, or the
   // upper half of the shift amount is zero.  Just use the lower half.
   SDValue Lo, Hi;
   GetExpandedInteger(N->getOperand(1), Lo, Hi);
   return SDValue(DAG.UpdateNodeOperands(N, N->getOperand(0), Lo), 0);
 }

lib/CodeGen/SelectionDAG/LegalizeTypes.h

private:
   bool ExpandShiftWithUnknownAmountBit(SDNode *N, SDValue &Lo, SDValue &Hi);
 
   // Integer Operand Expansion.
   bool ExpandIntegerOperand(SDNode *N, unsigned OperandNo);
   SDValue ExpandIntOp_BR_CC(SDNode *N);
   SDValue ExpandIntOp_SELECT_CC(SDNode *N);
   SDValue ExpandIntOp_SETCC(SDNode *N);
   SDValue ExpandIntOp_SETCCE(SDNode *N);
+  SDValue ExpandIntOp_SETCCCARRY(SDNode *N);
   SDValue ExpandIntOp_Shift(SDNode *N);
   SDValue ExpandIntOp_SINT_TO_FP(SDNode *N);
   SDValue ExpandIntOp_STORE(StoreSDNode *N, unsigned OpNo);
   SDValue ExpandIntOp_TRUNCATE(SDNode *N);
   SDValue ExpandIntOp_UINT_TO_FP(SDNode *N);
   SDValue ExpandIntOp_RETURNADDR(SDNode *N);
   SDValue ExpandIntOp_ATOMIC_STORE(SDNode *N);
 

lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp

#endif
   case ISD::SMIN:                       return "smin";
   case ISD::SMAX:                       return "smax";
   case ISD::UMIN:                       return "umin";
   case ISD::UMAX:                       return "umax";
 
   case ISD::FPOWI:                      return "fpowi";
   case ISD::SETCC:                      return "setcc";
   case ISD::SETCCE:                     return "setcce";
+  case ISD::SETCCCARRY:                 return "setcccarry";
   case ISD::SELECT:                     return "select";
   case ISD::VSELECT:                    return "vselect";
   case ISD::SELECT_CC:                  return "select_cc";
   case ISD::INSERT_VECTOR_ELT:          return "insert_vector_elt";
   case ISD::EXTRACT_VECTOR_ELT:         return "extract_vector_elt";
   case ISD::CONCAT_VECTORS:             return "concat_vectors";
   case ISD::INSERT_SUBVECTOR:           return "insert_subvector";
   case ISD::EXTRACT_SUBVECTOR:          return "extract_subvector";

lib/CodeGen/TargetLoweringBase.cpp

for (MVT VT : MVT::all_valuetypes()) {
     setOperationAction(ISD::UADDO, VT, Expand);
     setOperationAction(ISD::USUBO, VT, Expand);
     setOperationAction(ISD::SMULO, VT, Expand);
     setOperationAction(ISD::UMULO, VT, Expand);
 
     // ADDCARRY operations default to expand
     setOperationAction(ISD::ADDCARRY, VT, Expand);
     setOperationAction(ISD::SUBCARRY, VT, Expand);
+    setOperationAction(ISD::SETCCCARRY, VT, Expand);
 
     // These default to Expand so they will be expanded to CTLZ/CTTZ by default.
     setOperationAction(ISD::CTLZ_ZERO_UNDEF, VT, Expand);
     setOperationAction(ISD::CTTZ_ZERO_UNDEF, VT, Expand);
 
     setOperationAction(ISD::BITREVERSE, VT, Expand);
     
     // These library functions default to expand.

lib/Target/X86/X86ISelLowering.h

private:
     SDValue LowerUINT_TO_FP_i32(SDValue Op, SelectionDAG &DAG) const;
     SDValue lowerUINT_TO_FP_vec(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerTRUNCATE(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerFP_TO_INT(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerToBT(SDValue And, ISD::CondCode CC, const SDLoc &dl,
                       SelectionDAG &DAG) const;
     SDValue LowerSETCC(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerSETCCE(SDValue Op, SelectionDAG &DAG) const;
+    SDValue LowerSETCCCARRY(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerSELECT(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerBRCOND(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerJumpTable(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerVASTART(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerVAARG(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerRETURNADDR(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerADDROFRETURNADDR(SDValue Op, SelectionDAG &DAG) const;

lib/Target/X86/X86ISelLowering.cpp

for (auto VT : { MVT::i8, MVT::i16, MVT::i32, MVT::i64 }) {
     setOperationAction(ISD::SSUBO, VT, Custom);
     setOperationAction(ISD::USUBO, VT, Custom);
     setOperationAction(ISD::SMULO, VT, Custom);
     setOperationAction(ISD::UMULO, VT, Custom);
 
     // Support carry in as value rather than glue.
     setOperationAction(ISD::ADDCARRY, VT, Custom);
     setOperationAction(ISD::SUBCARRY, VT, Custom);
+    setOperationAction(ISD::SETCCCARRY, VT, Custom);
   }
 
   if (!Subtarget.is64Bit()) {
     // These libcalls are not available in 32-bit.
     setLibcallName(RTLIB::SHL_I128, nullptr);
     setLibcallName(RTLIB::SRL_I128, nullptr);
     setLibcallName(RTLIB::SRA_I128, nullptr);
   }
SDValue X86TargetLowering::LowerSETCCE(SDValue Op, SelectionDAG &DAG) const {
   SDVTList VTs = DAG.getVTList(LHS.getValueType(), MVT::i32);
   SDValue Cmp = DAG.getNode(X86ISD::SBB, DL, VTs, LHS, RHS, Carry);
   SDValue SetCC = getSETCC(CC, Cmp.getValue(1), DL, DAG);
   if (Op.getSimpleValueType() == MVT::i1)
     return DAG.getNode(ISD::TRUNCATE, DL, MVT::i1, SetCC);
   return SetCC;
 }
 
+SDValue X86TargetLowering::LowerSETCCCARRY(SDValue Op, SelectionDAG &DAG) const {
+  SDValue LHS = Op.getOperand(0);
+  SDValue RHS = Op.getOperand(1);
+  SDValue Carry = Op.getOperand(2);
+  SDValue Cond = Op.getOperand(3);
+  SDLoc DL(Op);
+
+  assert(LHS.getSimpleValueType().isInteger() && "SETCCCARRY is integer only.");
+  X86::CondCode CC = TranslateIntegerX86CC(cast<CondCodeSDNode>(Cond)->get());
+
+  // Recreate the carry if needed.
+  EVT CarryVT = Carry.getValueType();
+  APInt NegOne = APInt::getAllOnesValue(CarryVT.getScalarSizeInBits());
+  Carry = DAG.getNode(X86ISD::ADD, DL, DAG.getVTList(CarryVT, MVT::i32),
+                      Carry, DAG.getConstant(NegOne, DL, CarryVT));
+
+  SDVTList VTs = DAG.getVTList(LHS.getValueType(), MVT::i32);
+  SDValue Cmp = DAG.getNode(X86ISD::SBB, DL, VTs, LHS, RHS, Carry.getValue(1));
+  SDValue SetCC = getSETCC(CC, Cmp.getValue(1), DL, DAG);
+  if (Op.getSimpleValueType() == MVT::i1)
+    return DAG.getNode(ISD::TRUNCATE, DL, MVT::i1, SetCC);
+  return SetCC;
+}
+
 /// Return true if opcode is a X86 logical comparison.
 static bool isX86LogicalCmp(SDValue Op) {
   unsigned Opc = Op.getOpcode();
   if (Opc == X86ISD::CMP || Opc == X86ISD::COMI || Opc == X86ISD::UCOMI ||
       Opc == X86ISD::SAHF)
     return true;
   if (Op.getResNo() == 1 &&
       (Opc == X86ISD::ADD || Opc == X86ISD::SUB || Opc == X86ISD::ADC ||
SDValue X86TargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
   case ISD::FP_EXTEND:          return LowerFP_EXTEND(Op, DAG);
   case ISD::LOAD:               return LowerExtendedLoad(Op, Subtarget, DAG);
   case ISD::FABS:
   case ISD::FNEG:               return LowerFABSorFNEG(Op, DAG);
   case ISD::FCOPYSIGN:          return LowerFCOPYSIGN(Op, DAG);
   case ISD::FGETSIGN:           return LowerFGETSIGN(Op, DAG);
   case ISD::SETCC:              return LowerSETCC(Op, DAG);
   case ISD::SETCCE:             return LowerSETCCE(Op, DAG);
+  case ISD::SETCCCARRY:         return LowerSETCCCARRY(Op, DAG);
   case ISD::SELECT:             return LowerSELECT(Op, DAG);
   case ISD::BRCOND:             return LowerBRCOND(Op, DAG);
   case ISD::JumpTable:          return LowerJumpTable(Op, DAG);
   case ISD::VASTART:            return LowerVASTART(Op, DAG);
   case ISD::VAARG:              return LowerVAARG(Op, DAG);
   case ISD::VACOPY:             return LowerVACOPY(Op, Subtarget, DAG);
   case ISD::INTRINSIC_WO_CHAIN: return LowerINTRINSIC_WO_CHAIN(Op, Subtarget, DAG);
   case ISD::INTRINSIC_VOID:
if (isAllOnesConstant(N->getOperand(1)) && N->hasAnyUseOfValue(1)) {
     while (Carry.getOpcode() == ISD::TRUNCATE ||
            Carry.getOpcode() == ISD::ZERO_EXTEND ||
            Carry.getOpcode() == ISD::SIGN_EXTEND ||
            Carry.getOpcode() == ISD::ANY_EXTEND ||
            (Carry.getOpcode() == ISD::AND &&
             isOneConstant(Carry.getOperand(1))))
       Carry = Carry.getOperand(0);
 
-    if (Carry.getOpcode() == ISD::SETCC ||
-        Carry.getOpcode() == X86ISD::SETCC ||
+    if (Carry.getOpcode() == X86ISD::SETCC ||
         Carry.getOpcode() == X86ISD::SETCC_CARRY) {
       if (Carry.getConstantOperandVal(0) == X86::COND_B)
         return DCI.CombineTo(N, SDValue(N, 0), Carry.getOperand(1));
     }
   }
 
   return SDValue();
 }

test/CodeGen/X86/wide-integer-cmp.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=i686-linux-gnu %s -o - | FileCheck %s
 
-
 define i32 @branch_eq(i64 %a, i64 %b) {
 ; CHECK-LABEL: branch_eq:
 ; CHECK:       # BB#0: # %entry
 ; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
 ; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %ecx
 ; CHECK-NEXT:    xorl {{[0-9]+}}(%esp), %ecx
 ; CHECK-NEXT:    xorl {{[0-9]+}}(%esp), %eax
 ; CHECK-NEXT:    orl %ecx, %eax