diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -5032,16 +5032,17 @@
     return SDValue();
 
   SDValue Shift, Factor;
-  if (VT.isFixedLengthVector()) {
+  if (Op1.getOpcode() == ISD::BUILD_VECTOR) {
     Shift = DAG.getBuildVector(ShVT, dl, Shifts);
     Factor = DAG.getBuildVector(VT, dl, Factors);
-  } else if (VT.isScalableVector()) {
+  } else if (Op1.getOpcode() == ISD::SPLAT_VECTOR) {
     assert(Shifts.size() == 1 && Factors.size() == 1 &&
            "Expected matchUnaryPredicate to return one element for scalable "
            "vectors");
     Shift = DAG.getSplatVector(ShVT, dl, Shifts[0]);
     Factor = DAG.getSplatVector(VT, dl, Factors[0]);
   } else {
+    assert(isa<ConstantSDNode>(Op1) && "Expected a constant");
     Shift = Shifts[0];
     Factor = Factors[0];
   }
@@ -5147,12 +5148,12 @@
     return SDValue();
 
   SDValue MagicFactor, Factor, Shift, ShiftMask;
-  if (VT.isFixedLengthVector()) {
+  if (N1.getOpcode() == ISD::BUILD_VECTOR) {
     MagicFactor = DAG.getBuildVector(VT, dl, MagicFactors);
     Factor = DAG.getBuildVector(VT, dl, Factors);
     Shift = DAG.getBuildVector(ShVT, dl, Shifts);
     ShiftMask = DAG.getBuildVector(VT, dl, ShiftMasks);
-  } else if (VT.isScalableVector()) {
+  } else if (N1.getOpcode() == ISD::SPLAT_VECTOR) {
     assert(MagicFactors.size() == 1 && Factors.size() == 1 &&
            Shifts.size() == 1 && ShiftMasks.size() == 1 &&
            "Expected matchUnaryPredicate to return one element for scalable "
@@ -5162,6 +5163,7 @@
     Shift = DAG.getSplatVector(ShVT, dl, Shifts[0]);
     ShiftMask = DAG.getSplatVector(VT, dl, ShiftMasks[0]);
   } else {
+    assert(isa<ConstantSDNode>(N1) && "Expected a constant");
     MagicFactor = MagicFactors[0];
     Factor = Factors[0];
     Shift = Shifts[0];
@@ -5303,12 +5305,12 @@
     return SDValue();
 
   SDValue PreShift, PostShift, MagicFactor, NPQFactor;
-  if (VT.isFixedLengthVector()) {
+  if (N1.getOpcode() == ISD::BUILD_VECTOR) {
     PreShift = DAG.getBuildVector(ShVT, dl, PreShifts);
     MagicFactor = DAG.getBuildVector(VT, dl, MagicFactors);
     NPQFactor = DAG.getBuildVector(VT, dl, NPQFactors);
     PostShift = DAG.getBuildVector(ShVT, dl, PostShifts);
-  } else if (VT.isScalableVector()) {
+  } else if (N1.getOpcode() == ISD::SPLAT_VECTOR) {
     assert(PreShifts.size() == 1 && MagicFactors.size() == 1 &&
            NPQFactors.size() == 1 && PostShifts.size() == 1 &&
            "Expected matchUnaryPredicate to return one for scalable vectors");
@@ -5317,6 +5319,7 @@
     NPQFactor = DAG.getSplatVector(VT, dl, NPQFactors[0]);
     PostShift = DAG.getSplatVector(ShVT, dl, PostShifts[0]);
   } else {
+    assert(isa<ConstantSDNode>(N1) && "Expected a constant");
     PreShift = PreShifts[0];
     MagicFactor = MagicFactors[0];
     PostShift = PostShifts[0];
@@ -5806,7 +5809,7 @@
     return SDValue();
 
   SDValue PVal, AVal, KVal, QVal;
-  if (VT.isFixedLengthVector()) {
+  if (D.getOpcode() == ISD::BUILD_VECTOR) {
     if (HadOneDivisor) {
       // Try to turn PAmts into a splat, since we don't care about the values
       // that are currently '0'. If we can't, just keep '0'`s.
@@ -5825,7 +5828,7 @@
     AVal = DAG.getBuildVector(VT, DL, AAmts);
     KVal = DAG.getBuildVector(ShVT, DL, KAmts);
     QVal = DAG.getBuildVector(VT, DL, QAmts);
-  } else if (VT.isScalableVector()) {
+  } else if (D.getOpcode() == ISD::SPLAT_VECTOR) {
     assert(PAmts.size() == 1 && AAmts.size() == 1 && KAmts.size() == 1 &&
            QAmts.size() == 1 &&
            "Expected matchUnaryPredicate to return one element for scalable "
@@ -5835,6 +5838,7 @@
     KVal = DAG.getSplatVector(ShVT, DL, KAmts[0]);
     QVal = DAG.getSplatVector(VT, DL, QAmts[0]);
   } else {
+    assert(isa<ConstantSDNode>(D) && "Expected a constant");
     PVal = PAmts[0];
     AVal = AAmts[0];
     KVal = KAmts[0];
diff --git a/llvm/test/CodeGen/AArch64/sve-fixed-length-int-div.ll b/llvm/test/CodeGen/AArch64/sve-fixed-length-int-div.ll
--- a/llvm/test/CodeGen/AArch64/sve-fixed-length-int-div.ll
+++ b/llvm/test/CodeGen/AArch64/sve-fixed-length-int-div.ll
@@ -968,4 +968,20 @@
   ret void
 }
 
+; This used to crash because isUnaryPredicate and BuildUDIV don't know how
+; a SPLAT_VECTOR of fixed vector type should be handled.
+define void @udiv_constantsplat_v8i32(<8 x i32>* %a) #0 {
+; CHECK-LABEL: udiv_constantsplat_v8i32:
+; CHECK: ptrue [[PG:p[0-9]+]].s, vl[[#min(div(VBYTES,4),8)]]
+; CHECK-NEXT: ld1w { [[OP1:z[0-9]+]].s }, [[PG]]/z, [x0]
+; CHECK-NEXT: mov [[OP2:z[0-9]+]].s, #95
+; CHECK-NEXT: udiv [[RES:z[0-9]+]].s, [[PG]]/m, [[OP1]].s, [[OP2]].s
+; CHECK-NEXT: st1w { [[RES]].s }, [[PG]], [x0]
+; CHECK-NEXT: ret
+  %op1 = load <8 x i32>, <8 x i32>* %a
+  %res = udiv <8 x i32> %op1, <i32 95, i32 95, i32 95, i32 95, i32 95, i32 95, i32 95, i32 95>
+  store <8 x i32> %res, <8 x i32>* %a
+  ret void
+}
+
 attributes #0 = { "target-features"="+sve" }