Index: lib/CodeGen/SelectionDAG/LegalizeTypes.h
===================================================================
--- lib/CodeGen/SelectionDAG/LegalizeTypes.h
+++ lib/CodeGen/SelectionDAG/LegalizeTypes.h
@@ -627,6 +627,7 @@
   SDValue ScalarizeVecOp_CONCAT_VECTORS(SDNode *N);
   SDValue ScalarizeVecOp_EXTRACT_VECTOR_ELT(SDNode *N);
   SDValue ScalarizeVecOp_VSELECT(SDNode *N);
+  SDValue ScalarizeVecOp_VSETCC(SDNode *N);
   SDValue ScalarizeVecOp_STORE(StoreSDNode *N, unsigned OpNo);
   SDValue ScalarizeVecOp_FP_ROUND(SDNode *N, unsigned OpNo);
 
Index: lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -484,6 +484,9 @@
     case ISD::VSELECT:
       Res = ScalarizeVecOp_VSELECT(N);
       break;
+    case ISD::SETCC:
+      Res = ScalarizeVecOp_VSETCC(N);
+      break;
     case ISD::STORE:
       Res = ScalarizeVecOp_STORE(cast<StoreSDNode>(N), OpNo);
       break;
@@ -560,6 +563,36 @@
                      N->getOperand(2));
 }
 
+/// If the operand is a vector that needs to be scalarized then the
+/// result must be v1i1, so just convert to a scalar SETCC and wrap
+/// with a scalar_to_vector since the res type is legal if we got here
+SDValue DAGTypeLegalizer::ScalarizeVecOp_VSETCC(SDNode *N) {
+  assert(N->getValueType(0).isVector() &&
+         N->getOperand(0).getValueType().isVector() &&
+         "Operand types must be vectors");
+  assert(N->getValueType(0) == MVT::v1i1 && "Expected v1i1 type");
+
+  EVT VT = N->getValueType(0);
+  SDValue LHS = GetScalarizedVector(N->getOperand(0));
+  SDValue RHS = GetScalarizedVector(N->getOperand(1));
+
+  EVT OpVT = N->getOperand(0).getValueType();
+  EVT NVT = VT.getVectorElementType();
+  SDLoc DL(N);
+  // Turn it into a scalar SETCC.
+  SDValue Res = DAG.getNode(ISD::SETCC, DL, MVT::i1, LHS, RHS,
+      N->getOperand(2));
+
+  // Vectors may have a different boolean contents to scalars.  Promote the
+  // value appropriately.
+  ISD::NodeType ExtendCode =
+      TargetLowering::getExtendForContent(TLI.getBooleanContents(OpVT));
+
+  Res = DAG.getNode(ExtendCode, DL, NVT, Res);
+
+  return DAG.getNode(ISD::SCALAR_TO_VECTOR, DL, VT, Res);
+}
+
 /// If the value to store is a vector that needs to be scalarized, it must be
 /// <1 x ty>. Just store the element.
 SDValue DAGTypeLegalizer::ScalarizeVecOp_STORE(StoreSDNode *N, unsigned OpNo){
Index: test/CodeGen/X86/pr34177.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/pr34177.ll
@@ -0,0 +1,52 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mattr=+avx512f | FileCheck %s
+; RUN: llc < %s -mattr=+avx512f,+avx512vl,+avx512bw,+avx512dq | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @test() local_unnamed_addr {
+; CHECK-LABEL: test:
+; CHECK:       # BB#0:
+; CHECK-NEXT:    vmovdqa {{.*#+}} xmm0 = [2,3]
+; CHECK-NEXT:    vpextrq $1, %xmm0, %rax
+; CHECK-NEXT:    vmovq %xmm0, %rcx
+; CHECK-NEXT:    negq %rdx
+; CHECK-NEXT:    fld1
+; CHECK-NEXT:    fldz
+; CHECK-NEXT:    fld %st(0)
+; CHECK-NEXT:    fcmove %st(2), %st(0)
+; CHECK-NEXT:    cmpq %rax, %rcx
+; CHECK-NEXT:    fld %st(1)
+; CHECK-NEXT:    fcmove %st(3), %st(0)
+; CHECK-NEXT:    cmpq %rax, %rax
+; CHECK-NEXT:    fld %st(2)
+; CHECK-NEXT:    fcmove %st(4), %st(0)
+; CHECK-NEXT:    movl $1, %eax
+; CHECK-NEXT:    cmpq %rax, %rax
+; CHECK-NEXT:    fld %st(3)
+; CHECK-NEXT:    fcmove %st(5), %st(0)
+; CHECK-NEXT:    fstp %st(5)
+; CHECK-NEXT:    fxch %st(2)
+; CHECK-NEXT:    fadd %st(3)
+; CHECK-NEXT:    fxch %st(4)
+; CHECK-NEXT:    fadd %st(3)
+; CHECK-NEXT:    fxch %st(2)
+; CHECK-NEXT:    fadd %st(3)
+; CHECK-NEXT:    fxch %st(1)
+; CHECK-NEXT:    faddp %st(3)
+; CHECK-NEXT:    fxch %st(3)
+; CHECK-NEXT:    fstpt (%rax)
+; CHECK-NEXT:    fxch %st(1)
+; CHECK-NEXT:    fstpt (%rax)
+; CHECK-NEXT:    fxch %st(1)
+; CHECK-NEXT:    fstpt (%rax)
+; CHECK-NEXT:    fstpt (%rax)
+  %1 = icmp eq <4 x i64> <i64 0, i64 1, i64 2, i64 3>, undef
+  %2 = select <4 x i1> %1, <4 x x86_fp80> <x86_fp80 0xK3FFF8000000000000000, x86_fp80 0xK3FFF8000000000000000, x86_fp80 0xK3FFF8000000000000000, x86_fp80 0xK3FFF8000000000000000>, <4 x x86_fp80> zeroinitializer
+  %3 = fadd <4 x x86_fp80> undef, %2
+  %4 = shufflevector <4 x x86_fp80> %3, <4 x x86_fp80> undef, <8 x i32> <i32 0, i32 4, i32 1, i32 5, i32 2, i32 6, i32 3, i32 7>
+  store <8 x x86_fp80> %4, <8 x x86_fp80>* undef, align 16
+  unreachable
+}
+