[LegalizeDAG] Remove dead SINT_TO_FP legalization code

[RKSimon]

Summary

As noticed on D52965, the SINT_TO_FP i64 to f32 legalization code has been dead for years - protected by an assert.

[craig.topper]

LGTM

lib/CodeGen/SelectionDAG/LegalizeDAG.cpp

SDValue SelectionDAGLegalize::ExpandLegalINT_TO_FP(bool isSigned, SDValue Op0,
   assert(!isSigned && "Legalize cannot Expand SINT_TO_FP for i64 yet");
   // Code below here assumes !isSigned without checking again.
 
   // TODO: Generalize this for use with other types.
   if (SrcVT == MVT::i64 && DestVT == MVT::f32) {
     LLVM_DEBUG(dbgs() << "Converting unsigned i64 to f32\n");
     // For unsigned conversions, convert them to signed conversions using the
     // algorithm from the x86_64 __floatundidf in compiler_rt.
-    if (!isSigned) {
-      SDValue Fast = DAG.getNode(ISD::SINT_TO_FP, dl, DestVT, Op0);
 
-      SDValue ShiftConst = DAG.getConstant(1, dl, ShiftVT);
-      SDValue Shr = DAG.getNode(ISD::SRL, dl, SrcVT, Op0, ShiftConst);
-      SDValue AndConst = DAG.getConstant(1, dl, SrcVT);
-      SDValue And = DAG.getNode(ISD::AND, dl, SrcVT, Op0, AndConst);
-      SDValue Or = DAG.getNode(ISD::OR, dl, SrcVT, And, Shr);
 
-      SDValue SignCvt = DAG.getNode(ISD::SINT_TO_FP, dl, DestVT, Or);
-      SDValue Slow = DAG.getNode(ISD::FADD, dl, DestVT, SignCvt, SignCvt);
 
-      // TODO: This really should be implemented using a branch rather than a
-      // select.  We happen to get lucky and machinesink does the right
-      // thing most of the time.  This would be a good candidate for a
-      // pseudo-op, or, even better, for whole-function isel.
-      SDValue SignBitTest =
-          DAG.getSetCC(dl, getSetCCResultType(SrcVT), Op0,
-                       DAG.getConstant(0, dl, SrcVT), ISD::SETLT);
-      return DAG.getSelect(dl, DestVT, SignBitTest, Slow, Fast);
-    }
 
-    // Otherwise, implement the fully general conversion.
-
-    SDValue And = DAG.getNode(ISD::AND, dl, MVT::i64, Op0,
-         DAG.getConstant(UINT64_C(0xfffffffffffff800), dl, MVT::i64));
-    SDValue Or = DAG.getNode(ISD::OR, dl, MVT::i64, And,
-         DAG.getConstant(UINT64_C(0x800), dl, MVT::i64));
-    SDValue And2 = DAG.getNode(ISD::AND, dl, MVT::i64, Op0,
-         DAG.getConstant(UINT64_C(0x7ff), dl, MVT::i64));
-    SDValue Ne = DAG.getSetCC(dl, getSetCCResultType(MVT::i64), And2,
-                              DAG.getConstant(UINT64_C(0), dl, MVT::i64),
-                              ISD::SETNE);
-    SDValue Sel = DAG.getSelect(dl, MVT::i64, Ne, Or, Op0);
-    SDValue Ge = DAG.getSetCC(dl, getSetCCResultType(MVT::i64), Op0,
-                              DAG.getConstant(UINT64_C(0x0020000000000000), dl,
-                                              MVT::i64),
-                              ISD::SETUGE);
-    SDValue Sel2 = DAG.getSelect(dl, MVT::i64, Ge, Sel, Op0);
-    EVT SHVT = TLI.getShiftAmountTy(Sel2.getValueType(), DAG.getDataLayout());
-
-    SDValue Sh = DAG.getNode(ISD::SRL, dl, MVT::i64, Sel2,
-                             DAG.getConstant(32, dl, SHVT));
-    SDValue Trunc = DAG.getNode(ISD::TRUNCATE, dl, MVT::i32, Sh);
-    SDValue Fcvt = DAG.getNode(ISD::UINT_TO_FP, dl, MVT::f64, Trunc);
-    SDValue TwoP32 =
-      DAG.getConstantFP(BitsToDouble(UINT64_C(0x41f0000000000000)), dl,
-                        MVT::f64);
-    SDValue Fmul = DAG.getNode(ISD::FMUL, dl, MVT::f64, TwoP32, Fcvt);
-    SDValue Lo = DAG.getNode(ISD::TRUNCATE, dl, MVT::i32, Sel2);
-    SDValue Fcvt2 = DAG.getNode(ISD::UINT_TO_FP, dl, MVT::f64, Lo);
-    SDValue Fadd = DAG.getNode(ISD::FADD, dl, MVT::f64, Fmul, Fcvt2);
-    return DAG.getNode(ISD::FP_ROUND, dl, MVT::f32, Fadd,
-                       DAG.getIntPtrConstant(0, dl));
-  }
-
   SDValue Tmp1 = DAG.getNode(ISD::SINT_TO_FP, dl, DestVT, Op0);
 
   SDValue SignSet = DAG.getSetCC(dl, getSetCCResultType(SrcVT), Op0,
                                  DAG.getConstant(0, dl, SrcVT), ISD::SETLT);
   SDValue Zero = DAG.getIntPtrConstant(0, dl),
           Four = DAG.getIntPtrConstant(4, dl);
   SDValue CstOffset = DAG.getSelect(dl, Zero.getValueType(),
                                     SignSet, Four, Zero);