diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index fa3dce256046f..6483e07afadee 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -2654,6 +2654,10 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
                        ISD::AVGCEILU,
                        ISD::AVGFLOORS,
                        ISD::AVGFLOORU,
+                       ISD::CTLZ,
+                       ISD::CTTZ,
+                       ISD::CTLZ_ZERO_UNDEF,
+                       ISD::CTTZ_ZERO_UNDEF,
                        ISD::BITREVERSE,
                        ISD::ADD,
                        ISD::FADD,
@@ -55162,6 +55166,65 @@ static SDValue combineXor(SDNode *N, SelectionDAG &DAG,
   return combineFneg(N, DAG, DCI, Subtarget);
 }
 
+// Fold i256/i512 CTLZ/CTTZ patterns to make use of AVX512
+// vXi64 CTLZ/CTTZ and VECTOR_COMPRESS.
+// Compute the CTLZ/CTTZ of each element, add the element's bit offset, compress
+// the result to remove all zero elements (passthru is set to scalar bitwidth if
+// all elements are zero) and extract the lowest compressed element.
+static SDValue combineCTZ(SDNode *N, SelectionDAG &DAG,
+                          TargetLowering::DAGCombinerInfo &DCI,
+                          const X86Subtarget &Subtarget) {
+  EVT VT = N->getValueType(0);
+  SDValue N0 = N->getOperand(0);
+  unsigned Opc = N->getOpcode();
+  unsigned SizeInBits = VT.getSizeInBits();
+  assert((Opc == ISD::CTLZ || Opc == ISD::CTLZ_ZERO_UNDEF || Opc == ISD::CTTZ ||
+          Opc == ISD::CTTZ_ZERO_UNDEF) &&
+         "Unsupported bit count");
+
+  if (VT.isScalarInteger() && Subtarget.hasCDI() &&
+      ((SizeInBits == 512 && Subtarget.useAVX512Regs()) ||
+       (SizeInBits == 256 && Subtarget.hasVLX() &&
+        X86::mayFoldLoad(N0, Subtarget)))) {
+    MVT VecVT = MVT::getVectorVT(MVT::i64, SizeInBits / 64);
+    MVT BoolVT = VecVT.changeVectorElementType(MVT::i1);
+    SDValue Vec = DAG.getBitcast(VecVT, N0);
+    SDLoc DL(N);
+
+    SmallVector<int, 8> RevMask;
+    SmallVector<SDValue, 8> Offsets;
+    for (unsigned I = 0, E = VecVT.getVectorNumElements(); I != E; ++I) {
+      RevMask.push_back((int)((E - 1) - I));
+      Offsets.push_back(DAG.getConstant(I * 64, DL, MVT::i64));
+    }
+
+    // CTLZ - reverse the elements as we want the top non-zero element at the
+    // bottom for compression.
+    unsigned VecOpc = ISD::CTTZ;
+    if (Opc == ISD::CTLZ || Opc == ISD::CTLZ_ZERO_UNDEF) {
+      VecOpc = ISD::CTLZ;
+      Vec = DAG.getVectorShuffle(VecVT, DL, Vec, Vec, RevMask);
+    }
+
+    SDValue PassThrough = DAG.getUNDEF(VecVT);
+    if (Opc == ISD::CTLZ || Opc == ISD::CTTZ)
+      PassThrough = DAG.getConstant(SizeInBits, DL, VecVT);
+
+    SDValue IsNonZero = DAG.getSetCC(DL, BoolVT, Vec,
+                                     DAG.getConstant(0, DL, VecVT), ISD::SETNE);
+    SDValue Cnt = DAG.getNode(VecOpc, DL, VecVT, Vec);
+    Cnt = DAG.getNode(ISD::ADD, DL, VecVT, Cnt,
+                      DAG.getBuildVector(VecVT, DL, Offsets));
+    Cnt = DAG.getNode(ISD::VECTOR_COMPRESS, DL, VecVT, Cnt, IsNonZero,
+                      PassThrough);
+    Cnt = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, DL, MVT::i64, Cnt,
+                      DAG.getVectorIdxConstant(0, DL));
+    return DAG.getZExtOrTrunc(Cnt, DL, VT);
+  }
+
+  return SDValue();
+}
+
 static SDValue combineBITREVERSE(SDNode *N, SelectionDAG &DAG,
                                  TargetLowering::DAGCombinerInfo &DCI,
                                  const X86Subtarget &Subtarget) {
@@ -60885,6 +60948,10 @@ SDValue X86TargetLowering::PerformDAGCombine(SDNode *N,
   case ISD::AND:            return combineAnd(N, DAG, DCI, Subtarget);
   case ISD::OR:             return combineOr(N, DAG, DCI, Subtarget);
   case ISD::XOR:            return combineXor(N, DAG, DCI, Subtarget);
+  case ISD::CTLZ:
+  case ISD::CTTZ:
+  case ISD::CTLZ_ZERO_UNDEF:
+  case ISD::CTTZ_ZERO_UNDEF:return combineCTZ(N, DAG, DCI, Subtarget);
   case ISD::BITREVERSE:     return combineBITREVERSE(N, DAG, DCI, Subtarget);
   case ISD::AVGCEILS:
   case ISD::AVGCEILU:
diff --git a/llvm/test/CodeGen/X86/bitcnt-big-integer.ll b/llvm/test/CodeGen/X86/bitcnt-big-integer.ll
index fe3fbf141682a..330c978d2a9f7 100644
--- a/llvm/test/CodeGen/X86/bitcnt-big-integer.ll
+++ b/llvm/test/CodeGen/X86/bitcnt-big-integer.ll
@@ -1,8 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
 ; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=x86-64-v2 | FileCheck %s --check-prefixes=CHECK,SSE
 ; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=x86-64-v3 | FileCheck %s --check-prefixes=CHECK,AVX2
-; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=x86-64-v4 | FileCheck %s --check-prefixes=CHECK,AVX512
-; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=x86-64-v4 -mattr=+avx512vpopcntdq | FileCheck %s --check-prefixes=CHECK,AVX512
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=x86-64-v4 | FileCheck %s --check-prefixes=CHECK,AVX512,AVX512F
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=x86-64-v4 -mattr=+avx512vpopcntdq | FileCheck %s --check-prefixes=CHECK,AVX512,AVX512POPCNT
 
 ;
 ; CTPOP
@@ -712,23 +712,15 @@ define i32 @load_ctlz_i256(ptr %p0) nounwind {
 ;
 ; AVX512-LABEL: load_ctlz_i256:
 ; AVX512:       # %bb.0:
-; AVX512-NEXT:    movq 8(%rdi), %rcx
-; AVX512-NEXT:    movq 16(%rdi), %rdx
-; AVX512-NEXT:    movq 24(%rdi), %rsi
-; AVX512-NEXT:    lzcntq %rsi, %rax
-; AVX512-NEXT:    lzcntq %rdx, %r8
-; AVX512-NEXT:    addl $64, %r8d
-; AVX512-NEXT:    testq %rsi, %rsi
-; AVX512-NEXT:    cmovnel %eax, %r8d
-; AVX512-NEXT:    lzcntq %rcx, %r9
-; AVX512-NEXT:    lzcntq (%rdi), %rax
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %rcx, %rcx
-; AVX512-NEXT:    cmovnel %r9d, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %rsi, %rdx
-; AVX512-NEXT:    cmovnel %r8d, %eax
+; AVX512-NEXT:    vpermq {{.*#+}} ymm0 = mem[3,2,1,0]
+; AVX512-NEXT:    vplzcntq %ymm0, %ymm1
+; AVX512-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %ymm1, %ymm1
+; AVX512-NEXT:    vptestmq %ymm0, %ymm0, %k1
+; AVX512-NEXT:    vpbroadcastq {{.*#+}} ymm0 = [256,256,256,256]
+; AVX512-NEXT:    vpcompressq %ymm1, %ymm0 {%k1}
+; AVX512-NEXT:    vmovq %xmm0, %rax
 ; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512-NEXT:    vzeroupper
 ; AVX512-NEXT:    retq
   %a0 = load i256, ptr %p0
   %cnt = call i256 @llvm.ctlz.i256(i256 %a0, i1 0)
@@ -845,47 +837,28 @@ define i32 @test_ctlz_i512(i512 %a0) nounwind {
 ;
 ; AVX512-LABEL: test_ctlz_i512:
 ; AVX512:       # %bb.0:
-; AVX512-NEXT:    pushq %r15
-; AVX512-NEXT:    pushq %r14
-; AVX512-NEXT:    pushq %rbx
-; AVX512-NEXT:    movq {{[0-9]+}}(%rsp), %r10
-; AVX512-NEXT:    movq {{[0-9]+}}(%rsp), %r11
-; AVX512-NEXT:    lzcntq %r11, %rax
-; AVX512-NEXT:    lzcntq %r10, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %r11, %r11
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    lzcntq %r9, %rax
-; AVX512-NEXT:    lzcntq %r8, %rbx
-; AVX512-NEXT:    addl $64, %ebx
-; AVX512-NEXT:    testq %r9, %r9
-; AVX512-NEXT:    cmovnel %eax, %ebx
-; AVX512-NEXT:    subl $-128, %ebx
-; AVX512-NEXT:    movq %r10, %rax
-; AVX512-NEXT:    orq %r11, %rax
-; AVX512-NEXT:    cmovnel %r14d, %ebx
-; AVX512-NEXT:    lzcntq %rcx, %rax
-; AVX512-NEXT:    lzcntq %rdx, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %rcx, %rcx
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    lzcntq %rsi, %r15
-; AVX512-NEXT:    lzcntq %rdi, %rax
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %rsi, %rsi
-; AVX512-NEXT:    cmovnel %r15d, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %rcx, %rdx
-; AVX512-NEXT:    cmovnel %r14d, %eax
-; AVX512-NEXT:    addl $256, %eax # imm = 0x100
-; AVX512-NEXT:    orq %r11, %r9
-; AVX512-NEXT:    orq %r10, %r8
-; AVX512-NEXT:    orq %r9, %r8
-; AVX512-NEXT:    cmovnel %ebx, %eax
-; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
-; AVX512-NEXT:    popq %rbx
-; AVX512-NEXT:    popq %r14
-; AVX512-NEXT:    popq %r15
+; AVX512-NEXT:    vmovq %rdi, %xmm0
+; AVX512-NEXT:    vmovq %rsi, %xmm1
+; AVX512-NEXT:    vpunpcklqdq {{.*#+}} xmm0 = xmm1[0],xmm0[0]
+; AVX512-NEXT:    vmovq %rdx, %xmm1
+; AVX512-NEXT:    vmovq %rcx, %xmm2
+; AVX512-NEXT:    vpunpcklqdq {{.*#+}} xmm1 = xmm2[0],xmm1[0]
+; AVX512-NEXT:    vinserti128 $1, %xmm0, %ymm1, %ymm0
+; AVX512-NEXT:    vmovq %r8, %xmm1
+; AVX512-NEXT:    vmovq %r9, %xmm2
+; AVX512-NEXT:    vpunpcklqdq {{.*#+}} xmm1 = xmm2[0],xmm1[0]
+; AVX512-NEXT:    vmovq {{.*#+}} xmm2 = mem[0],zero
+; AVX512-NEXT:    vmovq {{.*#+}} xmm3 = mem[0],zero
+; AVX512-NEXT:    vpunpcklqdq {{.*#+}} xmm2 = xmm3[0],xmm2[0]
+; AVX512-NEXT:    vinserti128 $1, %xmm1, %ymm2, %ymm1
+; AVX512-NEXT:    vinserti64x4 $1, %ymm0, %zmm1, %zmm0
+; AVX512-NEXT:    vplzcntq %zmm0, %zmm1
+; AVX512-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %zmm1, %zmm1
+; AVX512-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512-NEXT:    vpbroadcastq {{.*#+}} zmm0 = [512,512,512,512,512,512,512,512]
+; AVX512-NEXT:    vpcompressq %zmm1, %zmm0 {%k1}
+; AVX512-NEXT:    vmovd %xmm0, %eax
+; AVX512-NEXT:    vzeroupper
 ; AVX512-NEXT:    retq
   %cnt = call i512 @llvm.ctlz.i512(i512 %a0, i1 0)
   %res = trunc i512 %cnt to i32
@@ -1010,50 +983,16 @@ define i32 @load_ctlz_i512(ptr %p0) nounwind {
 ;
 ; AVX512-LABEL: load_ctlz_i512:
 ; AVX512:       # %bb.0:
-; AVX512-NEXT:    pushq %r14
-; AVX512-NEXT:    pushq %rbx
-; AVX512-NEXT:    movq 8(%rdi), %r11
-; AVX512-NEXT:    movq 16(%rdi), %r9
-; AVX512-NEXT:    movq 24(%rdi), %r10
-; AVX512-NEXT:    movq 32(%rdi), %rcx
-; AVX512-NEXT:    movq 40(%rdi), %rdx
-; AVX512-NEXT:    movq 48(%rdi), %rsi
-; AVX512-NEXT:    movq 56(%rdi), %r8
-; AVX512-NEXT:    lzcntq %r8, %rax
-; AVX512-NEXT:    lzcntq %rsi, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %r8, %r8
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    lzcntq %rdx, %rax
-; AVX512-NEXT:    lzcntq %rcx, %rbx
-; AVX512-NEXT:    addl $64, %ebx
-; AVX512-NEXT:    testq %rdx, %rdx
-; AVX512-NEXT:    cmovnel %eax, %ebx
-; AVX512-NEXT:    subl $-128, %ebx
-; AVX512-NEXT:    movq %rsi, %rax
-; AVX512-NEXT:    orq %r8, %rax
-; AVX512-NEXT:    cmovnel %r14d, %ebx
-; AVX512-NEXT:    lzcntq %r10, %rax
-; AVX512-NEXT:    lzcntq %r9, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %r10, %r10
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    lzcntq (%rdi), %rax
-; AVX512-NEXT:    lzcntq %r11, %rdi
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %r11, %r11
-; AVX512-NEXT:    cmovnel %edi, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %r10, %r9
-; AVX512-NEXT:    cmovnel %r14d, %eax
-; AVX512-NEXT:    addl $256, %eax # imm = 0x100
-; AVX512-NEXT:    orq %r8, %rdx
-; AVX512-NEXT:    orq %rsi, %rcx
-; AVX512-NEXT:    orq %rdx, %rcx
-; AVX512-NEXT:    cmovnel %ebx, %eax
+; AVX512-NEXT:    vmovdqa64 {{.*#+}} zmm0 = [7,6,5,4,3,2,1,0]
+; AVX512-NEXT:    vpermq (%rdi), %zmm0, %zmm0
+; AVX512-NEXT:    vplzcntq %zmm0, %zmm1
+; AVX512-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %zmm1, %zmm1
+; AVX512-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512-NEXT:    vpbroadcastq {{.*#+}} zmm0 = [512,512,512,512,512,512,512,512]
+; AVX512-NEXT:    vpcompressq %zmm1, %zmm0 {%k1}
+; AVX512-NEXT:    vmovq %xmm0, %rax
 ; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
-; AVX512-NEXT:    popq %rbx
-; AVX512-NEXT:    popq %r14
+; AVX512-NEXT:    vzeroupper
 ; AVX512-NEXT:    retq
   %a0 = load i512, ptr %p0
   %cnt = call i512 @llvm.ctlz.i512(i512 %a0, i1 0)
@@ -2002,23 +1941,14 @@ define i32 @load_ctlz_undef_i256(ptr %p0) nounwind {
 ;
 ; AVX512-LABEL: load_ctlz_undef_i256:
 ; AVX512:       # %bb.0:
-; AVX512-NEXT:    movq 8(%rdi), %rcx
-; AVX512-NEXT:    movq 16(%rdi), %rdx
-; AVX512-NEXT:    movq 24(%rdi), %rsi
-; AVX512-NEXT:    lzcntq %rsi, %rax
-; AVX512-NEXT:    lzcntq %rdx, %r8
-; AVX512-NEXT:    addl $64, %r8d
-; AVX512-NEXT:    testq %rsi, %rsi
-; AVX512-NEXT:    cmovnel %eax, %r8d
-; AVX512-NEXT:    lzcntq %rcx, %r9
-; AVX512-NEXT:    lzcntq (%rdi), %rax
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %rcx, %rcx
-; AVX512-NEXT:    cmovnel %r9d, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %rsi, %rdx
-; AVX512-NEXT:    cmovnel %r8d, %eax
+; AVX512-NEXT:    vpermq {{.*#+}} ymm0 = mem[3,2,1,0]
+; AVX512-NEXT:    vptestmq %ymm0, %ymm0, %k1
+; AVX512-NEXT:    vplzcntq %ymm0, %ymm0
+; AVX512-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %ymm0, %ymm0
+; AVX512-NEXT:    vpcompressq %ymm0, %ymm0 {%k1} {z}
+; AVX512-NEXT:    vmovq %xmm0, %rax
 ; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512-NEXT:    vzeroupper
 ; AVX512-NEXT:    retq
   %a0 = load i256, ptr %p0
   %cnt = call i256 @llvm.ctlz.i256(i256 %a0, i1 -1)
@@ -2134,47 +2064,27 @@ define i32 @test_ctlz_undef_i512(i512 %a0) nounwind {
 ;
 ; AVX512-LABEL: test_ctlz_undef_i512:
 ; AVX512:       # %bb.0:
-; AVX512-NEXT:    pushq %r15
-; AVX512-NEXT:    pushq %r14
-; AVX512-NEXT:    pushq %rbx
-; AVX512-NEXT:    movq {{[0-9]+}}(%rsp), %r10
-; AVX512-NEXT:    movq {{[0-9]+}}(%rsp), %r11
-; AVX512-NEXT:    lzcntq %r11, %rax
-; AVX512-NEXT:    lzcntq %r10, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %r11, %r11
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    lzcntq %r9, %rax
-; AVX512-NEXT:    lzcntq %r8, %rbx
-; AVX512-NEXT:    addl $64, %ebx
-; AVX512-NEXT:    testq %r9, %r9
-; AVX512-NEXT:    cmovnel %eax, %ebx
-; AVX512-NEXT:    subl $-128, %ebx
-; AVX512-NEXT:    movq %r10, %rax
-; AVX512-NEXT:    orq %r11, %rax
-; AVX512-NEXT:    cmovnel %r14d, %ebx
-; AVX512-NEXT:    lzcntq %rcx, %rax
-; AVX512-NEXT:    lzcntq %rdx, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %rcx, %rcx
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    lzcntq %rsi, %r15
-; AVX512-NEXT:    lzcntq %rdi, %rax
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %rsi, %rsi
-; AVX512-NEXT:    cmovnel %r15d, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %rcx, %rdx
-; AVX512-NEXT:    cmovnel %r14d, %eax
-; AVX512-NEXT:    addl $256, %eax # imm = 0x100
-; AVX512-NEXT:    orq %r11, %r9
-; AVX512-NEXT:    orq %r10, %r8
-; AVX512-NEXT:    orq %r9, %r8
-; AVX512-NEXT:    cmovnel %ebx, %eax
-; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
-; AVX512-NEXT:    popq %rbx
-; AVX512-NEXT:    popq %r14
-; AVX512-NEXT:    popq %r15
+; AVX512-NEXT:    vmovq %rdi, %xmm0
+; AVX512-NEXT:    vmovq %rsi, %xmm1
+; AVX512-NEXT:    vpunpcklqdq {{.*#+}} xmm0 = xmm1[0],xmm0[0]
+; AVX512-NEXT:    vmovq %rdx, %xmm1
+; AVX512-NEXT:    vmovq %rcx, %xmm2
+; AVX512-NEXT:    vpunpcklqdq {{.*#+}} xmm1 = xmm2[0],xmm1[0]
+; AVX512-NEXT:    vinserti128 $1, %xmm0, %ymm1, %ymm0
+; AVX512-NEXT:    vmovq %r8, %xmm1
+; AVX512-NEXT:    vmovq %r9, %xmm2
+; AVX512-NEXT:    vpunpcklqdq {{.*#+}} xmm1 = xmm2[0],xmm1[0]
+; AVX512-NEXT:    vmovq {{.*#+}} xmm2 = mem[0],zero
+; AVX512-NEXT:    vmovq {{.*#+}} xmm3 = mem[0],zero
+; AVX512-NEXT:    vpunpcklqdq {{.*#+}} xmm2 = xmm3[0],xmm2[0]
+; AVX512-NEXT:    vinserti128 $1, %xmm1, %ymm2, %ymm1
+; AVX512-NEXT:    vinserti64x4 $1, %ymm0, %zmm1, %zmm0
+; AVX512-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512-NEXT:    vplzcntq %zmm0, %zmm0
+; AVX512-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %zmm0, %zmm0
+; AVX512-NEXT:    vpcompressq %zmm0, %zmm0 {%k1} {z}
+; AVX512-NEXT:    vmovd %xmm0, %eax
+; AVX512-NEXT:    vzeroupper
 ; AVX512-NEXT:    retq
   %cnt = call i512 @llvm.ctlz.i512(i512 %a0, i1 -1)
   %res = trunc i512 %cnt to i32
@@ -2298,50 +2208,15 @@ define i32 @load_ctlz_undef_i512(ptr %p0) nounwind {
 ;
 ; AVX512-LABEL: load_ctlz_undef_i512:
 ; AVX512:       # %bb.0:
-; AVX512-NEXT:    pushq %r14
-; AVX512-NEXT:    pushq %rbx
-; AVX512-NEXT:    movq 8(%rdi), %r11
-; AVX512-NEXT:    movq 16(%rdi), %r9
-; AVX512-NEXT:    movq 24(%rdi), %r10
-; AVX512-NEXT:    movq 32(%rdi), %rcx
-; AVX512-NEXT:    movq 40(%rdi), %rdx
-; AVX512-NEXT:    movq 48(%rdi), %rsi
-; AVX512-NEXT:    movq 56(%rdi), %r8
-; AVX512-NEXT:    lzcntq %r8, %rax
-; AVX512-NEXT:    lzcntq %rsi, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %r8, %r8
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    lzcntq %rdx, %rax
-; AVX512-NEXT:    lzcntq %rcx, %rbx
-; AVX512-NEXT:    addl $64, %ebx
-; AVX512-NEXT:    testq %rdx, %rdx
-; AVX512-NEXT:    cmovnel %eax, %ebx
-; AVX512-NEXT:    subl $-128, %ebx
-; AVX512-NEXT:    movq %rsi, %rax
-; AVX512-NEXT:    orq %r8, %rax
-; AVX512-NEXT:    cmovnel %r14d, %ebx
-; AVX512-NEXT:    lzcntq %r10, %rax
-; AVX512-NEXT:    lzcntq %r9, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %r10, %r10
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    lzcntq (%rdi), %rax
-; AVX512-NEXT:    lzcntq %r11, %rdi
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %r11, %r11
-; AVX512-NEXT:    cmovnel %edi, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %r10, %r9
-; AVX512-NEXT:    cmovnel %r14d, %eax
-; AVX512-NEXT:    addl $256, %eax # imm = 0x100
-; AVX512-NEXT:    orq %r8, %rdx
-; AVX512-NEXT:    orq %rsi, %rcx
-; AVX512-NEXT:    orq %rdx, %rcx
-; AVX512-NEXT:    cmovnel %ebx, %eax
+; AVX512-NEXT:    vmovdqa64 {{.*#+}} zmm0 = [7,6,5,4,3,2,1,0]
+; AVX512-NEXT:    vpermq (%rdi), %zmm0, %zmm0
+; AVX512-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512-NEXT:    vplzcntq %zmm0, %zmm0
+; AVX512-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %zmm0, %zmm0
+; AVX512-NEXT:    vpcompressq %zmm0, %zmm0 {%k1} {z}
+; AVX512-NEXT:    vmovq %xmm0, %rax
 ; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
-; AVX512-NEXT:    popq %rbx
-; AVX512-NEXT:    popq %r14
+; AVX512-NEXT:    vzeroupper
 ; AVX512-NEXT:    retq
   %a0 = load i512, ptr %p0
   %cnt = call i512 @llvm.ctlz.i512(i512 %a0, i1 -1)
@@ -3282,26 +3157,38 @@ define i32 @load_cttz_i256(ptr %p0) nounwind {
 ; AVX2-NEXT:    # kill: def $eax killed $eax killed $rax
 ; AVX2-NEXT:    retq
 ;
-; AVX512-LABEL: load_cttz_i256:
-; AVX512:       # %bb.0:
-; AVX512-NEXT:    movq 16(%rdi), %rcx
-; AVX512-NEXT:    movq (%rdi), %rdx
-; AVX512-NEXT:    movq 8(%rdi), %rsi
-; AVX512-NEXT:    tzcntq %rdx, %rax
-; AVX512-NEXT:    tzcntq %rsi, %r8
-; AVX512-NEXT:    addl $64, %r8d
-; AVX512-NEXT:    testq %rdx, %rdx
-; AVX512-NEXT:    cmovnel %eax, %r8d
-; AVX512-NEXT:    tzcntq %rcx, %r9
-; AVX512-NEXT:    tzcntq 24(%rdi), %rax
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %rcx, %rcx
-; AVX512-NEXT:    cmovnel %r9d, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %rsi, %rdx
-; AVX512-NEXT:    cmovnel %r8d, %eax
-; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
-; AVX512-NEXT:    retq
+; AVX512F-LABEL: load_cttz_i256:
+; AVX512F:       # %bb.0:
+; AVX512F-NEXT:    vmovdqu (%rdi), %ymm0
+; AVX512F-NEXT:    vpcmpeqd %ymm1, %ymm1, %ymm1
+; AVX512F-NEXT:    vpaddq %ymm1, %ymm0, %ymm1
+; AVX512F-NEXT:    vpandn %ymm1, %ymm0, %ymm1
+; AVX512F-NEXT:    vplzcntq %ymm1, %ymm1
+; AVX512F-NEXT:    vmovdqa {{.*#+}} ymm2 = [64,128,192,256]
+; AVX512F-NEXT:    vpsubq %ymm1, %ymm2, %ymm1
+; AVX512F-NEXT:    vptestmq %ymm0, %ymm0, %k1
+; AVX512F-NEXT:    vpbroadcastq {{.*#+}} ymm0 = [256,256,256,256]
+; AVX512F-NEXT:    vpcompressq %ymm1, %ymm0 {%k1}
+; AVX512F-NEXT:    vmovq %xmm0, %rax
+; AVX512F-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512F-NEXT:    vzeroupper
+; AVX512F-NEXT:    retq
+;
+; AVX512POPCNT-LABEL: load_cttz_i256:
+; AVX512POPCNT:       # %bb.0:
+; AVX512POPCNT-NEXT:    vmovdqu (%rdi), %ymm0
+; AVX512POPCNT-NEXT:    vpcmpeqd %ymm1, %ymm1, %ymm1
+; AVX512POPCNT-NEXT:    vpaddq %ymm1, %ymm0, %ymm1
+; AVX512POPCNT-NEXT:    vpandn %ymm1, %ymm0, %ymm1
+; AVX512POPCNT-NEXT:    vpopcntq %ymm1, %ymm1
+; AVX512POPCNT-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %ymm1, %ymm1
+; AVX512POPCNT-NEXT:    vptestmq %ymm0, %ymm0, %k1
+; AVX512POPCNT-NEXT:    vpbroadcastq {{.*#+}} ymm0 = [256,256,256,256]
+; AVX512POPCNT-NEXT:    vpcompressq %ymm1, %ymm0 {%k1}
+; AVX512POPCNT-NEXT:    vmovq %xmm0, %rax
+; AVX512POPCNT-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512POPCNT-NEXT:    vzeroupper
+; AVX512POPCNT-NEXT:    retq
   %a0 = load i256, ptr %p0
   %cnt = call i256 @llvm.cttz.i256(i256 %a0, i1 0)
   %res = trunc i256 %cnt to i32
@@ -3399,47 +3286,58 @@ define i32 @test_cttz_i512(i512 %a0) nounwind {
 ; AVX2-NEXT:    popq %r14
 ; AVX2-NEXT:    retq
 ;
-; AVX512-LABEL: test_cttz_i512:
-; AVX512:       # %bb.0:
-; AVX512-NEXT:    pushq %r14
-; AVX512-NEXT:    pushq %rbx
-; AVX512-NEXT:    movq {{[0-9]+}}(%rsp), %r11
-; AVX512-NEXT:    tzcntq %rdi, %rax
-; AVX512-NEXT:    tzcntq %rsi, %rbx
-; AVX512-NEXT:    addl $64, %ebx
-; AVX512-NEXT:    testq %rdi, %rdi
-; AVX512-NEXT:    cmovnel %eax, %ebx
-; AVX512-NEXT:    tzcntq %rdx, %rax
-; AVX512-NEXT:    tzcntq %rcx, %r10
-; AVX512-NEXT:    addl $64, %r10d
-; AVX512-NEXT:    testq %rdx, %rdx
-; AVX512-NEXT:    cmovnel %eax, %r10d
-; AVX512-NEXT:    subl $-128, %r10d
-; AVX512-NEXT:    movq %rdi, %rax
-; AVX512-NEXT:    orq %rsi, %rax
-; AVX512-NEXT:    cmovnel %ebx, %r10d
-; AVX512-NEXT:    tzcntq %r8, %rax
-; AVX512-NEXT:    tzcntq %r9, %rbx
-; AVX512-NEXT:    addl $64, %ebx
-; AVX512-NEXT:    testq %r8, %r8
-; AVX512-NEXT:    cmovnel %eax, %ebx
-; AVX512-NEXT:    tzcntq {{[0-9]+}}(%rsp), %rax
-; AVX512-NEXT:    tzcntq %r11, %r14
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %r11, %r11
-; AVX512-NEXT:    cmovnel %r14d, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %r9, %r8
-; AVX512-NEXT:    cmovnel %ebx, %eax
-; AVX512-NEXT:    addl $256, %eax # imm = 0x100
-; AVX512-NEXT:    orq %rcx, %rsi
-; AVX512-NEXT:    orq %rdx, %rdi
-; AVX512-NEXT:    orq %rsi, %rdi
-; AVX512-NEXT:    cmovnel %r10d, %eax
-; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
-; AVX512-NEXT:    popq %rbx
-; AVX512-NEXT:    popq %r14
-; AVX512-NEXT:    retq
+; AVX512F-LABEL: test_cttz_i512:
+; AVX512F:       # %bb.0:
+; AVX512F-NEXT:    vmovq %rcx, %xmm0
+; AVX512F-NEXT:    vmovq %rdx, %xmm1
+; AVX512F-NEXT:    vpunpcklqdq {{.*#+}} xmm0 = xmm1[0],xmm0[0]
+; AVX512F-NEXT:    vmovq %rsi, %xmm1
+; AVX512F-NEXT:    vmovq %rdi, %xmm2
+; AVX512F-NEXT:    vpunpcklqdq {{.*#+}} xmm1 = xmm2[0],xmm1[0]
+; AVX512F-NEXT:    vinserti128 $1, %xmm0, %ymm1, %ymm0
+; AVX512F-NEXT:    vmovq %r9, %xmm1
+; AVX512F-NEXT:    vmovq %r8, %xmm2
+; AVX512F-NEXT:    vpunpcklqdq {{.*#+}} xmm1 = xmm2[0],xmm1[0]
+; AVX512F-NEXT:    vinserti128 $1, {{[0-9]+}}(%rsp), %ymm1, %ymm1
+; AVX512F-NEXT:    vinserti64x4 $1, %ymm1, %zmm0, %zmm0
+; AVX512F-NEXT:    vpternlogd {{.*#+}} zmm1 = -1
+; AVX512F-NEXT:    vpaddq %zmm1, %zmm0, %zmm1
+; AVX512F-NEXT:    vpandnq %zmm1, %zmm0, %zmm1
+; AVX512F-NEXT:    vplzcntq %zmm1, %zmm1
+; AVX512F-NEXT:    vmovdqa64 {{.*#+}} zmm2 = [64,128,192,256,320,384,448,512]
+; AVX512F-NEXT:    vpsubq %zmm1, %zmm2, %zmm1
+; AVX512F-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512F-NEXT:    vpbroadcastq {{.*#+}} zmm0 = [512,512,512,512,512,512,512,512]
+; AVX512F-NEXT:    vpcompressq %zmm1, %zmm0 {%k1}
+; AVX512F-NEXT:    vmovd %xmm0, %eax
+; AVX512F-NEXT:    vzeroupper
+; AVX512F-NEXT:    retq
+;
+; AVX512POPCNT-LABEL: test_cttz_i512:
+; AVX512POPCNT:       # %bb.0:
+; AVX512POPCNT-NEXT:    vmovq %rcx, %xmm0
+; AVX512POPCNT-NEXT:    vmovq %rdx, %xmm1
+; AVX512POPCNT-NEXT:    vpunpcklqdq {{.*#+}} xmm0 = xmm1[0],xmm0[0]
+; AVX512POPCNT-NEXT:    vmovq %rsi, %xmm1
+; AVX512POPCNT-NEXT:    vmovq %rdi, %xmm2
+; AVX512POPCNT-NEXT:    vpunpcklqdq {{.*#+}} xmm1 = xmm2[0],xmm1[0]
+; AVX512POPCNT-NEXT:    vinserti128 $1, %xmm0, %ymm1, %ymm0
+; AVX512POPCNT-NEXT:    vmovq %r9, %xmm1
+; AVX512POPCNT-NEXT:    vmovq %r8, %xmm2
+; AVX512POPCNT-NEXT:    vpunpcklqdq {{.*#+}} xmm1 = xmm2[0],xmm1[0]
+; AVX512POPCNT-NEXT:    vinserti128 $1, {{[0-9]+}}(%rsp), %ymm1, %ymm1
+; AVX512POPCNT-NEXT:    vinserti64x4 $1, %ymm1, %zmm0, %zmm0
+; AVX512POPCNT-NEXT:    vpternlogd {{.*#+}} zmm1 = -1
+; AVX512POPCNT-NEXT:    vpaddq %zmm1, %zmm0, %zmm1
+; AVX512POPCNT-NEXT:    vpandnq %zmm1, %zmm0, %zmm1
+; AVX512POPCNT-NEXT:    vpopcntq %zmm1, %zmm1
+; AVX512POPCNT-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %zmm1, %zmm1
+; AVX512POPCNT-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512POPCNT-NEXT:    vpbroadcastq {{.*#+}} zmm0 = [512,512,512,512,512,512,512,512]
+; AVX512POPCNT-NEXT:    vpcompressq %zmm1, %zmm0 {%k1}
+; AVX512POPCNT-NEXT:    vmovd %xmm0, %eax
+; AVX512POPCNT-NEXT:    vzeroupper
+; AVX512POPCNT-NEXT:    retq
   %cnt = call i512 @llvm.cttz.i512(i512 %a0, i1 0)
   %res = trunc i512 %cnt to i32
   ret i32 %res
@@ -3553,53 +3451,38 @@ define i32 @load_cttz_i512(ptr %p0) nounwind {
 ; AVX2-NEXT:    popq %r15
 ; AVX2-NEXT:    retq
 ;
-; AVX512-LABEL: load_cttz_i512:
-; AVX512:       # %bb.0:
-; AVX512-NEXT:    pushq %r14
-; AVX512-NEXT:    pushq %rbx
-; AVX512-NEXT:    movq 48(%rdi), %r11
-; AVX512-NEXT:    movq 40(%rdi), %r9
-; AVX512-NEXT:    movq 32(%rdi), %r10
-; AVX512-NEXT:    movq 24(%rdi), %r8
-; AVX512-NEXT:    movq 16(%rdi), %rdx
-; AVX512-NEXT:    movq (%rdi), %rcx
-; AVX512-NEXT:    movq 8(%rdi), %rsi
-; AVX512-NEXT:    tzcntq %rcx, %rax
-; AVX512-NEXT:    tzcntq %rsi, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %rcx, %rcx
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    tzcntq %rdx, %rax
-; AVX512-NEXT:    tzcntq %r8, %rbx
-; AVX512-NEXT:    addl $64, %ebx
-; AVX512-NEXT:    testq %rdx, %rdx
-; AVX512-NEXT:    cmovnel %eax, %ebx
-; AVX512-NEXT:    subl $-128, %ebx
-; AVX512-NEXT:    movq %rcx, %rax
-; AVX512-NEXT:    orq %rsi, %rax
-; AVX512-NEXT:    cmovnel %r14d, %ebx
-; AVX512-NEXT:    tzcntq %r10, %rax
-; AVX512-NEXT:    tzcntq %r9, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %r10, %r10
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    tzcntq 56(%rdi), %rax
-; AVX512-NEXT:    tzcntq %r11, %rdi
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %r11, %r11
-; AVX512-NEXT:    cmovnel %edi, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %r9, %r10
-; AVX512-NEXT:    cmovnel %r14d, %eax
-; AVX512-NEXT:    addl $256, %eax # imm = 0x100
-; AVX512-NEXT:    orq %r8, %rsi
-; AVX512-NEXT:    orq %rdx, %rcx
-; AVX512-NEXT:    orq %rsi, %rcx
-; AVX512-NEXT:    cmovnel %ebx, %eax
-; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
-; AVX512-NEXT:    popq %rbx
-; AVX512-NEXT:    popq %r14
-; AVX512-NEXT:    retq
+; AVX512F-LABEL: load_cttz_i512:
+; AVX512F:       # %bb.0:
+; AVX512F-NEXT:    vmovdqu64 (%rdi), %zmm0
+; AVX512F-NEXT:    vpternlogd {{.*#+}} zmm1 = -1
+; AVX512F-NEXT:    vpaddq %zmm1, %zmm0, %zmm1
+; AVX512F-NEXT:    vpandnq %zmm1, %zmm0, %zmm1
+; AVX512F-NEXT:    vplzcntq %zmm1, %zmm1
+; AVX512F-NEXT:    vmovdqa64 {{.*#+}} zmm2 = [64,128,192,256,320,384,448,512]
+; AVX512F-NEXT:    vpsubq %zmm1, %zmm2, %zmm1
+; AVX512F-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512F-NEXT:    vpbroadcastq {{.*#+}} zmm0 = [512,512,512,512,512,512,512,512]
+; AVX512F-NEXT:    vpcompressq %zmm1, %zmm0 {%k1}
+; AVX512F-NEXT:    vmovq %xmm0, %rax
+; AVX512F-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512F-NEXT:    vzeroupper
+; AVX512F-NEXT:    retq
+;
+; AVX512POPCNT-LABEL: load_cttz_i512:
+; AVX512POPCNT:       # %bb.0:
+; AVX512POPCNT-NEXT:    vmovdqu64 (%rdi), %zmm0
+; AVX512POPCNT-NEXT:    vpternlogd {{.*#+}} zmm1 = -1
+; AVX512POPCNT-NEXT:    vpaddq %zmm1, %zmm0, %zmm1
+; AVX512POPCNT-NEXT:    vpandnq %zmm1, %zmm0, %zmm1
+; AVX512POPCNT-NEXT:    vpopcntq %zmm1, %zmm1
+; AVX512POPCNT-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %zmm1, %zmm1
+; AVX512POPCNT-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512POPCNT-NEXT:    vpbroadcastq {{.*#+}} zmm0 = [512,512,512,512,512,512,512,512]
+; AVX512POPCNT-NEXT:    vpcompressq %zmm1, %zmm0 {%k1}
+; AVX512POPCNT-NEXT:    vmovq %xmm0, %rax
+; AVX512POPCNT-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512POPCNT-NEXT:    vzeroupper
+; AVX512POPCNT-NEXT:    retq
   %a0 = load i512, ptr %p0
   %cnt = call i512 @llvm.cttz.i512(i512 %a0, i1 0)
   %res = trunc i512 %cnt to i32
@@ -4492,26 +4375,36 @@ define i32 @load_cttz_undef_i256(ptr %p0) nounwind {
 ; AVX2-NEXT:    # kill: def $eax killed $eax killed $rax
 ; AVX2-NEXT:    retq
 ;
-; AVX512-LABEL: load_cttz_undef_i256:
-; AVX512:       # %bb.0:
-; AVX512-NEXT:    movq 16(%rdi), %rcx
-; AVX512-NEXT:    movq (%rdi), %rdx
-; AVX512-NEXT:    movq 8(%rdi), %rsi
-; AVX512-NEXT:    tzcntq %rdx, %rax
-; AVX512-NEXT:    tzcntq %rsi, %r8
-; AVX512-NEXT:    addl $64, %r8d
-; AVX512-NEXT:    testq %rdx, %rdx
-; AVX512-NEXT:    cmovnel %eax, %r8d
-; AVX512-NEXT:    tzcntq %rcx, %r9
-; AVX512-NEXT:    tzcntq 24(%rdi), %rax
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %rcx, %rcx
-; AVX512-NEXT:    cmovnel %r9d, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %rsi, %rdx
-; AVX512-NEXT:    cmovnel %r8d, %eax
-; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
-; AVX512-NEXT:    retq
+; AVX512F-LABEL: load_cttz_undef_i256:
+; AVX512F:       # %bb.0:
+; AVX512F-NEXT:    vmovdqu (%rdi), %ymm0
+; AVX512F-NEXT:    vpcmpeqd %ymm1, %ymm1, %ymm1
+; AVX512F-NEXT:    vpaddq %ymm1, %ymm0, %ymm1
+; AVX512F-NEXT:    vpandn %ymm1, %ymm0, %ymm1
+; AVX512F-NEXT:    vmovdqa {{.*#+}} ymm2 = [64,128,192,256]
+; AVX512F-NEXT:    vplzcntq %ymm1, %ymm1
+; AVX512F-NEXT:    vpsubq %ymm1, %ymm2, %ymm1
+; AVX512F-NEXT:    vptestmq %ymm0, %ymm0, %k1
+; AVX512F-NEXT:    vpcompressq %ymm1, %ymm0 {%k1} {z}
+; AVX512F-NEXT:    vmovq %xmm0, %rax
+; AVX512F-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512F-NEXT:    vzeroupper
+; AVX512F-NEXT:    retq
+;
+; AVX512POPCNT-LABEL: load_cttz_undef_i256:
+; AVX512POPCNT:       # %bb.0:
+; AVX512POPCNT-NEXT:    vmovdqu (%rdi), %ymm0
+; AVX512POPCNT-NEXT:    vpcmpeqd %ymm1, %ymm1, %ymm1
+; AVX512POPCNT-NEXT:    vpaddq %ymm1, %ymm0, %ymm1
+; AVX512POPCNT-NEXT:    vpandn %ymm1, %ymm0, %ymm1
+; AVX512POPCNT-NEXT:    vpopcntq %ymm1, %ymm1
+; AVX512POPCNT-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %ymm1, %ymm1
+; AVX512POPCNT-NEXT:    vptestmq %ymm0, %ymm0, %k1
+; AVX512POPCNT-NEXT:    vpcompressq %ymm1, %ymm0 {%k1} {z}
+; AVX512POPCNT-NEXT:    vmovq %xmm0, %rax
+; AVX512POPCNT-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512POPCNT-NEXT:    vzeroupper
+; AVX512POPCNT-NEXT:    retq
   %a0 = load i256, ptr %p0
   %cnt = call i256 @llvm.cttz.i256(i256 %a0, i1 -1)
   %res = trunc i256 %cnt to i32
@@ -4608,47 +4501,56 @@ define i32 @test_cttz_undef_i512(i512 %a0) nounwind {
 ; AVX2-NEXT:    popq %r14
 ; AVX2-NEXT:    retq
 ;
-; AVX512-LABEL: test_cttz_undef_i512:
-; AVX512:       # %bb.0:
-; AVX512-NEXT:    pushq %r14
-; AVX512-NEXT:    pushq %rbx
-; AVX512-NEXT:    movq {{[0-9]+}}(%rsp), %r11
-; AVX512-NEXT:    tzcntq %rdi, %rax
-; AVX512-NEXT:    tzcntq %rsi, %rbx
-; AVX512-NEXT:    addl $64, %ebx
-; AVX512-NEXT:    testq %rdi, %rdi
-; AVX512-NEXT:    cmovnel %eax, %ebx
-; AVX512-NEXT:    tzcntq %rdx, %rax
-; AVX512-NEXT:    tzcntq %rcx, %r10
-; AVX512-NEXT:    addl $64, %r10d
-; AVX512-NEXT:    testq %rdx, %rdx
-; AVX512-NEXT:    cmovnel %eax, %r10d
-; AVX512-NEXT:    subl $-128, %r10d
-; AVX512-NEXT:    movq %rdi, %rax
-; AVX512-NEXT:    orq %rsi, %rax
-; AVX512-NEXT:    cmovnel %ebx, %r10d
-; AVX512-NEXT:    tzcntq %r8, %rax
-; AVX512-NEXT:    tzcntq %r9, %rbx
-; AVX512-NEXT:    addl $64, %ebx
-; AVX512-NEXT:    testq %r8, %r8
-; AVX512-NEXT:    cmovnel %eax, %ebx
-; AVX512-NEXT:    tzcntq {{[0-9]+}}(%rsp), %rax
-; AVX512-NEXT:    tzcntq %r11, %r14
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %r11, %r11
-; AVX512-NEXT:    cmovnel %r14d, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %r9, %r8
-; AVX512-NEXT:    cmovnel %ebx, %eax
-; AVX512-NEXT:    addl $256, %eax # imm = 0x100
-; AVX512-NEXT:    orq %rcx, %rsi
-; AVX512-NEXT:    orq %rdx, %rdi
-; AVX512-NEXT:    orq %rsi, %rdi
-; AVX512-NEXT:    cmovnel %r10d, %eax
-; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
-; AVX512-NEXT:    popq %rbx
-; AVX512-NEXT:    popq %r14
-; AVX512-NEXT:    retq
+; AVX512F-LABEL: test_cttz_undef_i512:
+; AVX512F:       # %bb.0:
+; AVX512F-NEXT:    vmovq %rcx, %xmm0
+; AVX512F-NEXT:    vmovq %rdx, %xmm1
+; AVX512F-NEXT:    vpunpcklqdq {{.*#+}} xmm0 = xmm1[0],xmm0[0]
+; AVX512F-NEXT:    vmovq %rsi, %xmm1
+; AVX512F-NEXT:    vmovq %rdi, %xmm2
+; AVX512F-NEXT:    vpunpcklqdq {{.*#+}} xmm1 = xmm2[0],xmm1[0]
+; AVX512F-NEXT:    vinserti128 $1, %xmm0, %ymm1, %ymm0
+; AVX512F-NEXT:    vmovq %r9, %xmm1
+; AVX512F-NEXT:    vmovq %r8, %xmm2
+; AVX512F-NEXT:    vpunpcklqdq {{.*#+}} xmm1 = xmm2[0],xmm1[0]
+; AVX512F-NEXT:    vinserti128 $1, {{[0-9]+}}(%rsp), %ymm1, %ymm1
+; AVX512F-NEXT:    vinserti64x4 $1, %ymm1, %zmm0, %zmm0
+; AVX512F-NEXT:    vpternlogd {{.*#+}} zmm1 = -1
+; AVX512F-NEXT:    vpaddq %zmm1, %zmm0, %zmm1
+; AVX512F-NEXT:    vpandnq %zmm1, %zmm0, %zmm1
+; AVX512F-NEXT:    vmovdqa64 {{.*#+}} zmm2 = [64,128,192,256,320,384,448,512]
+; AVX512F-NEXT:    vplzcntq %zmm1, %zmm1
+; AVX512F-NEXT:    vpsubq %zmm1, %zmm2, %zmm1
+; AVX512F-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512F-NEXT:    vpcompressq %zmm1, %zmm0 {%k1} {z}
+; AVX512F-NEXT:    vmovd %xmm0, %eax
+; AVX512F-NEXT:    vzeroupper
+; AVX512F-NEXT:    retq
+;
+; AVX512POPCNT-LABEL: test_cttz_undef_i512:
+; AVX512POPCNT:       # %bb.0:
+; AVX512POPCNT-NEXT:    vmovq %rcx, %xmm0
+; AVX512POPCNT-NEXT:    vmovq %rdx, %xmm1
+; AVX512POPCNT-NEXT:    vpunpcklqdq {{.*#+}} xmm0 = xmm1[0],xmm0[0]
+; AVX512POPCNT-NEXT:    vmovq %rsi, %xmm1
+; AVX512POPCNT-NEXT:    vmovq %rdi, %xmm2
+; AVX512POPCNT-NEXT:    vpunpcklqdq {{.*#+}} xmm1 = xmm2[0],xmm1[0]
+; AVX512POPCNT-NEXT:    vmovq %r9, %xmm2
+; AVX512POPCNT-NEXT:    vmovq %r8, %xmm3
+; AVX512POPCNT-NEXT:    vpunpcklqdq {{.*#+}} xmm2 = xmm3[0],xmm2[0]
+; AVX512POPCNT-NEXT:    vinserti128 $1, {{[0-9]+}}(%rsp), %ymm2, %ymm2
+; AVX512POPCNT-NEXT:    vinserti128 $1, %xmm0, %ymm1, %ymm0
+; AVX512POPCNT-NEXT:    vinserti64x4 $1, %ymm2, %zmm0, %zmm0
+; AVX512POPCNT-NEXT:    vpternlogd {{.*#+}} zmm1 = -1
+; AVX512POPCNT-NEXT:    vpaddq %zmm1, %zmm0, %zmm1
+; AVX512POPCNT-NEXT:    vpandnq %zmm1, %zmm0, %zmm1
+; AVX512POPCNT-NEXT:    vpopcntq %zmm1, %zmm1
+; AVX512POPCNT-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %zmm1, %zmm1
+; AVX512POPCNT-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512POPCNT-NEXT:    vpcompressq %zmm1, %zmm0 {%k1} {z}
+; AVX512POPCNT-NEXT:    vmovd %xmm0, %eax
+; AVX512POPCNT-NEXT:    vzeroupper
+; AVX512POPCNT-NEXT:    retq
   %cnt = call i512 @llvm.cttz.i512(i512 %a0, i1 -1)
   %res = trunc i512 %cnt to i32
   ret i32 %res
@@ -4761,53 +4663,36 @@ define i32 @load_cttz_undef_i512(ptr %p0) nounwind {
 ; AVX2-NEXT:    popq %r15
 ; AVX2-NEXT:    retq
 ;
-; AVX512-LABEL: load_cttz_undef_i512:
-; AVX512:       # %bb.0:
-; AVX512-NEXT:    pushq %r14
-; AVX512-NEXT:    pushq %rbx
-; AVX512-NEXT:    movq 48(%rdi), %r11
-; AVX512-NEXT:    movq 40(%rdi), %r9
-; AVX512-NEXT:    movq 32(%rdi), %r10
-; AVX512-NEXT:    movq 24(%rdi), %r8
-; AVX512-NEXT:    movq 16(%rdi), %rdx
-; AVX512-NEXT:    movq (%rdi), %rcx
-; AVX512-NEXT:    movq 8(%rdi), %rsi
-; AVX512-NEXT:    tzcntq %rcx, %rax
-; AVX512-NEXT:    tzcntq %rsi, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %rcx, %rcx
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    tzcntq %rdx, %rax
-; AVX512-NEXT:    tzcntq %r8, %rbx
-; AVX512-NEXT:    addl $64, %ebx
-; AVX512-NEXT:    testq %rdx, %rdx
-; AVX512-NEXT:    cmovnel %eax, %ebx
-; AVX512-NEXT:    subl $-128, %ebx
-; AVX512-NEXT:    movq %rcx, %rax
-; AVX512-NEXT:    orq %rsi, %rax
-; AVX512-NEXT:    cmovnel %r14d, %ebx
-; AVX512-NEXT:    tzcntq %r10, %rax
-; AVX512-NEXT:    tzcntq %r9, %r14
-; AVX512-NEXT:    addl $64, %r14d
-; AVX512-NEXT:    testq %r10, %r10
-; AVX512-NEXT:    cmovnel %eax, %r14d
-; AVX512-NEXT:    tzcntq 56(%rdi), %rax
-; AVX512-NEXT:    tzcntq %r11, %rdi
-; AVX512-NEXT:    addl $64, %eax
-; AVX512-NEXT:    testq %r11, %r11
-; AVX512-NEXT:    cmovnel %edi, %eax
-; AVX512-NEXT:    subl $-128, %eax
-; AVX512-NEXT:    orq %r9, %r10
-; AVX512-NEXT:    cmovnel %r14d, %eax
-; AVX512-NEXT:    addl $256, %eax # imm = 0x100
-; AVX512-NEXT:    orq %r8, %rsi
-; AVX512-NEXT:    orq %rdx, %rcx
-; AVX512-NEXT:    orq %rsi, %rcx
-; AVX512-NEXT:    cmovnel %ebx, %eax
-; AVX512-NEXT:    # kill: def $eax killed $eax killed $rax
-; AVX512-NEXT:    popq %rbx
-; AVX512-NEXT:    popq %r14
-; AVX512-NEXT:    retq
+; AVX512F-LABEL: load_cttz_undef_i512:
+; AVX512F:       # %bb.0:
+; AVX512F-NEXT:    vmovdqu64 (%rdi), %zmm0
+; AVX512F-NEXT:    vpternlogd {{.*#+}} zmm1 = -1
+; AVX512F-NEXT:    vpaddq %zmm1, %zmm0, %zmm1
+; AVX512F-NEXT:    vpandnq %zmm1, %zmm0, %zmm1
+; AVX512F-NEXT:    vmovdqa64 {{.*#+}} zmm2 = [64,128,192,256,320,384,448,512]
+; AVX512F-NEXT:    vplzcntq %zmm1, %zmm1
+; AVX512F-NEXT:    vpsubq %zmm1, %zmm2, %zmm1
+; AVX512F-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512F-NEXT:    vpcompressq %zmm1, %zmm0 {%k1} {z}
+; AVX512F-NEXT:    vmovq %xmm0, %rax
+; AVX512F-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512F-NEXT:    vzeroupper
+; AVX512F-NEXT:    retq
+;
+; AVX512POPCNT-LABEL: load_cttz_undef_i512:
+; AVX512POPCNT:       # %bb.0:
+; AVX512POPCNT-NEXT:    vmovdqu64 (%rdi), %zmm0
+; AVX512POPCNT-NEXT:    vpternlogd {{.*#+}} zmm1 = -1
+; AVX512POPCNT-NEXT:    vpaddq %zmm1, %zmm0, %zmm1
+; AVX512POPCNT-NEXT:    vpandnq %zmm1, %zmm0, %zmm1
+; AVX512POPCNT-NEXT:    vpopcntq %zmm1, %zmm1
+; AVX512POPCNT-NEXT:    vpaddq {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %zmm1, %zmm1
+; AVX512POPCNT-NEXT:    vptestmq %zmm0, %zmm0, %k1
+; AVX512POPCNT-NEXT:    vpcompressq %zmm1, %zmm0 {%k1} {z}
+; AVX512POPCNT-NEXT:    vmovq %xmm0, %rax
+; AVX512POPCNT-NEXT:    # kill: def $eax killed $eax killed $rax
+; AVX512POPCNT-NEXT:    vzeroupper
+; AVX512POPCNT-NEXT:    retq
   %a0 = load i512, ptr %p0
   %cnt = call i512 @llvm.cttz.i512(i512 %a0, i1 -1)
   %res = trunc i512 %cnt to i32