[X86][SSE] Detect AVG pattern during instruction combine for SSE2/AVX2/AVX512BW.

[congh]

Summary

This patch detects the AVG pattern in vectorized code, which is simply c = (a + b + 1) / 2, where a, b, and c have the same type which are vectors of either unsigned i8 or unsigned i16. In the IR, i8/i16 will be promoted to i32 before any arithmetic operations. The following IR shows such an example:

%1 = zext <N x i8> %a to <N x i32>
%2 = zext <N x i8> %b to <N x i32>
%3 = add nuw nsw <N x i32> %1, <i32 1 x N>
%4 = add nuw nsw <N x i32> %3, %2
%5 = lshr <N x i32> %N, <i32 1 x N>
%6 = trunc <N x i32> %5 to <N x i8>

and with this patch it will be converted to a X86ISD::AVG instruction.

The pattern recognition is done when combining instructions just before type legalization during instruction selection. We do it here because after type legalization, it is much more difficult to do pattern recognition based on many instructions that are doing type conversions. Therefore, for target-specific instructions (like X86ISD::AVG), we need to take care of type legalization by ourselves. However, as X86ISD::AVG behaves similarly to ISD::ADD, I am wondering if there is a way to legalize operands and result types of X86ISD::AVG together with ISD::ADD. It seems that the current design doesn't support this idea.

Tests are added for SSE2, AVX2, and AVX512BW and both i8 and i16 types of variant vector sizes.

[RKSimon]

Out of curiosity - how well does this work with if InstCombiner::visitCallInst is used to convert _mm_avg_epu16 (etc.) calls to general IR? It should constant fold if possible - but could the lowering work if only one input is constant?

test/CodeGen/X86/avg.ll

5

AVX2/AVX512BW can share an additional AVX prefix - reduce test duplication:

FileCheck %s --check-prefix=AVX --check-prefix=AVX2
FileCheck %s --check-prefix=AVX --check-prefix=AVX512BW

6

What does the code look like if we load the args instead of passing them in registers? Non-legal types in these cases often make the test cases less clear - in this case with all the pand/packuswb calls.

[congh]

In D14761#294566, @RKSimon wrote:

Out of curiosity - how well does this work with if InstCombiner::visitCallInst is used to convert _mm_avg_epu16 (etc.) calls to general IR? It should constant fold if possible - but could the lowering work if only one input is constant?

I didn't consider the case that one input is constant, in which case we are detecting (a + C) / 2 where C is a 8-bit constant and is greater than zero. Then we could perform PAVGW on a and C-1. I will update this patch to take care of this case. Thanks!

test/CodeGen/X86/avg.ll

5

I don't get it here: I didn't use AVX prefix at all. Should I test all SSE versions?

6

If we load v4i8 from memory, those packing instructions will be gone. I will update the test cases.

[congh]

test/CodeGen/X86/avg.ll

5

Now I know what you mean: for some test cases AVX2 and AVX512BW generate the same code. Thanks for the suggestion!

[congh]

Update the patch. Now we can detect AVG pattern with one constant operand.

[RKSimon]

Couple of minor comments.

lib/Target/X86/X86ISelLowering.cpp

25286

Do the extended vector element types have to be i32? I understood it as it could be anything that was greater in width than the source.

AMD APM v4 description for PAVGB:

An average is computed by adding pairs of operands, adding 1 to a 9-bit temporary sum, and rightshifting the temporary sum by one bit position.

25309

If this is supposed to be FIXME comment please mark it as such.

25321

Standard Style:

for (unsigned i = 0, e = V.getNumOperands(); i != NumOperands; ++i)

[RKSimon]

lib/Target/X86/X86ISelLowering.cpp

25347

Shouldn't the upper limit be 65536 for pavgw?

[congh]

Update the patch according to Simon's comment.

lib/Target/X86/X86ISelLowering.cpp

25286

You are right. I have updated this part to let this type be larger than i8/i16 in case in the future we do type demotion on intermediate types.

25309

This is fixed already in this patch.

25347

Good catch! Corrected. Thanks!

[RKSimon]

LGTM - one minor query and please can you alter a couple of test cases so the zext extends to something other than vXi32? (vXi16 and vXi64 I guess).

lib/Target/X86/X86ISelLowering.cpp

25668–25669

Just to be certain - this can only be called for AVX512 truncate stores?

[congh]

In D14761#295365, @RKSimon wrote:

LGTM - one minor query and please can you alter a couple of test cases so the zext extends to something other than vXi32? (vXi16 and vXi64 I guess).

I have replaced many types in the test file with i16/i64.
Thank you very much for the review!

lib/Target/X86/X86ISelLowering.cpp

25668–25669

I am not sure if TruncatingStore can be generated for other platforms, but I think this is still valid other than AVX512. Let me know if I am wrong.

lib/Target/X86/X86ISelLowering.cpp

   setTargetDAGCombine(ISD::FADD);
   setTargetDAGCombine(ISD::FSUB);
   setTargetDAGCombine(ISD::FMA);
   setTargetDAGCombine(ISD::SUB);
   setTargetDAGCombine(ISD::LOAD);
   setTargetDAGCombine(ISD::MLOAD);
   setTargetDAGCombine(ISD::STORE);
   setTargetDAGCombine(ISD::MSTORE);
+  setTargetDAGCombine(ISD::TRUNCATE);
   setTargetDAGCombine(ISD::ZERO_EXTEND);
   setTargetDAGCombine(ISD::ANY_EXTEND);
   setTargetDAGCombine(ISD::SIGN_EXTEND);
   setTargetDAGCombine(ISD::SIGN_EXTEND_INREG);
   setTargetDAGCombine(ISD::SINT_TO_FP);
   setTargetDAGCombine(ISD::UINT_TO_FP);
   setTargetDAGCombine(ISD::SETCC);
   setTargetDAGCombine(ISD::BUILD_VECTOR);

 void X86TargetLowering::ReplaceNodeResults(SDNode *N,
                                            SmallVectorImpl<SDValue>&Results,
                                            SelectionDAG &DAG) const {
   SDLoc dl(N);
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
   switch (N->getOpcode()) {
   default:
     llvm_unreachable("Do not know how to custom type legalize this operation!");
+  case X86ISD::AVG: {
+    // Legalize types for X86ISD::AVG by expanding vectors.
+    assert(Subtarget->hasSSE2() && "Requires at least SSE2!");
+
+    auto InVT = N->getValueType(0);
+    auto InVTSize = InVT.getSizeInBits();
+    const unsigned RegSize =
+        (InVTSize > 128) ? ((InVTSize > 256) ? 512 : 256) : 128;
+    assert((!Subtarget->hasAVX512() || RegSize < 512) &&
+           "512-bit vector requires AVX512");
+    assert((!Subtarget->hasAVX2() || RegSize < 256) &&
+           "256-bit vector requires AVX2");
+
+    auto ElemVT = InVT.getVectorElementType();
+    auto RegVT = EVT::getVectorVT(*DAG.getContext(), ElemVT,
+                                  RegSize / ElemVT.getSizeInBits());
+    assert(RegSize % InVT.getSizeInBits() == 0);
+    unsigned NumConcat = RegSize / InVT.getSizeInBits();
+
+    SmallVector<SDValue, 16> Ops(NumConcat, DAG.getUNDEF(InVT));
+    Ops[0] = N->getOperand(0);
+    SDValue InVec0 = DAG.getNode(ISD::CONCAT_VECTORS, dl, RegVT, Ops);
+    Ops[0] = N->getOperand(1);
+    SDValue InVec1 = DAG.getNode(ISD::CONCAT_VECTORS, dl, RegVT, Ops);
+
+    SDValue Res = DAG.getNode(X86ISD::AVG, dl, RegVT, InVec0, InVec1);
+    Results.push_back(DAG.getNode(ISD::EXTRACT_SUBVECTOR, dl, InVT, Res,
+                                  DAG.getIntPtrConstant(0, dl)));
+    return;
+  }
   // We might have generated v2f32 FMIN/FMAX operations. Widen them to v4f32.
   case X86ISD::FMINC:
   case X86ISD::FMIN:
   case X86ISD::FMAXC:
   case X86ISD::FMAX: {
     EVT VT = N->getValueType(0);
     assert(VT == MVT::v2f32 && "Unexpected type (!= v2f32) on FMIN/FMAX.");
     SDValue UNDEF = DAG.getUNDEF(VT);
if (SDValue RV = performIntegerAbsCombine(N, DAG))
       return RV;
 
   if (SDValue FPLogic = convertIntLogicToFPLogic(N, DAG, Subtarget))
     return FPLogic;
 
   return SDValue();
 }
 
+/// This function detects the AVG pattern between vectors of unsigned i8/i16,
+/// which is c = (a + b + 1) / 2, and replace this operation with the efficient
+/// X86ISD::AVG instruction.
+static SDValue detectAVGPattern(SDValue In, EVT VT, SelectionDAG &DAG,
+                                const X86Subtarget *Subtarget, SDLoc DL) {
+  if (!VT.isVector() || !VT.isSimple())
+    return SDValue();
+  EVT InVT = In.getValueType();
+  unsigned NumElems = VT.getVectorNumElements();
+
+  EVT ScalarVT = VT.getVectorElementType();
+  if (!((ScalarVT == MVT::i8 || ScalarVT == MVT::i16) &&
+        isPowerOf2_32(NumElems)))
+    return SDValue();
+
+  // InScalarVT is the intermediate type in AVG pattern and it should be greater
+  // than the original input type (i8/i16).
+  EVT InScalarVT = InVT.getVectorElementType();
+  if (InScalarVT.getSizeInBits() <= ScalarVT.getSizeInBits())
+    return SDValue();
+
+  if (Subtarget->hasAVX512()) {
+    if (VT.getSizeInBits() > 512)
+      return SDValue();
+  } else if (Subtarget->hasAVX2()) {
+    if (VT.getSizeInBits() > 256)
+      return SDValue();
+  } else {
+    if (VT.getSizeInBits() > 128)
+      return SDValue();
+  }
+
+  // Detect the following pattern:
+  //
+  //   %1 = zext <N x i8> %a to <N x i32>
+  //   %2 = zext <N x i8> %b to <N x i32>
+  //   %3 = add nuw nsw <N x i32> %1, <i32 1 x N>
+  //   %4 = add nuw nsw <N x i32> %3, %2
+  //   %5 = lshr <N x i32> %N, <i32 1 x N>
+  //   %6 = trunc <N x i32> %5 to <N x i8>
+  //
+  // In AVX512, the last instruction can also be a trunc store.
+
+  if (In.getOpcode() != ISD::SRL)
+    return SDValue();
+
+  // A lambda checking the given SDValue is a constant vector and each element
+  // is in the range [Min, Max].
+  auto IsConstVectorInRange = [](SDValue V, unsigned Min, unsigned Max) {
+    BuildVectorSDNode *BV = dyn_cast<BuildVectorSDNode>(V);
+    if (!BV || !BV->isConstant())
+      return false;
+    for (unsigned i = 0, e = V.getNumOperands(); i < e; i++) {
+      ConstantSDNode *C = dyn_cast<ConstantSDNode>(V.getOperand(i));
+      if (!C)
+        return false;
+      uint64_t Val = C->getZExtValue();
+      if (Val < Min || Val > Max)
+        return false;
+    }
+    return true;
+  };
+
+  // Check if each element of the vector is left-shifted by one.
+  auto LHS = In.getOperand(0);
+  auto RHS = In.getOperand(1);
+  if (!IsConstVectorInRange(RHS, 1, 1))
+    return SDValue();
+  if (LHS.getOpcode() != ISD::ADD)
+    return SDValue();
+
+  // Detect a pattern of a + b + 1 where the order doesn't matter.
+  SDValue Operands[3];
+  Operands[0] = LHS.getOperand(0);
+  Operands[1] = LHS.getOperand(1);
+
+  // Take care of the case when one of the operands is a constant vector whose
+  // element is in the range [1, 256].
+  if (IsConstVectorInRange(Operands[1], 1, ScalarVT == MVT::i8 ? 256 : 65536) &&
+      Operands[0].getOpcode() == ISD::ZERO_EXTEND &&
+      Operands[0].getOperand(0).getValueType() == VT) {
+    // The pattern is detected. Subtract one from the constant vector, then
+    // demote it and emit X86ISD::AVG instruction.
+    SDValue One = DAG.getConstant(1, DL, InScalarVT);
+    SDValue Ones = DAG.getNode(ISD::BUILD_VECTOR, DL, InVT,
+                               SmallVector<SDValue, 8>(NumElems, One));
+    Operands[1] = DAG.getNode(ISD::SUB, DL, InVT, Operands[1], Ones);
+    Operands[1] = DAG.getNode(ISD::TRUNCATE, DL, VT, Operands[1]);
+    return DAG.getNode(X86ISD::AVG, DL, VT, Operands[0].getOperand(0),
+                       Operands[1]);
+  }
+
+  if (Operands[0].getOpcode() == ISD::ADD)
+    std::swap(Operands[0], Operands[1]);
+  else if (Operands[1].getOpcode() != ISD::ADD)
+    return SDValue();
+  Operands[2] = Operands[1].getOperand(0);
+  Operands[1] = Operands[1].getOperand(1);
+
+  // Now we have three operands of two additions. Check that one of them is a
+  // constant vector with ones, and the other two are promoted from i8/i16.
+  for (int i = 0; i < 3; ++i) {
+    if (!IsConstVectorInRange(Operands[i], 1, 1))
+      continue;
+    std::swap(Operands[i], Operands[2]);
+
+    // Check if Operands[0] and Operands[1] are results of type promotion.
+    for (int j = 0; j < 2; ++j)
+      if (Operands[j].getOpcode() != ISD::ZERO_EXTEND ||
+          Operands[j].getOperand(0).getValueType() != VT)
+        return SDValue();
+
+    // The pattern is detected, emit X86ISD::AVG instruction.
+    return DAG.getNode(X86ISD::AVG, DL, VT, Operands[0].getOperand(0),
+                       Operands[1].getOperand(0));
+  }
+
+  return SDValue();
+}
+
+static SDValue PerformTRUNCATECombine(SDNode *N, SelectionDAG &DAG,
+                                      const X86Subtarget *Subtarget) {
+  return detectAVGPattern(N->getOperand(0), N->getValueType(0), DAG, Subtarget,
+                          SDLoc(N));
+}
+
 /// PerformLOADCombine - Do target-specific dag combines on LOAD nodes.
 static SDValue PerformLOADCombine(SDNode *N, SelectionDAG &DAG,
                                   TargetLowering::DAGCombinerInfo &DCI,
                                   const X86Subtarget *Subtarget) {
   LoadSDNode *Ld = cast<LoadSDNode>(N);
   EVT RegVT = Ld->getValueType(0);
   EVT MemVT = Ld->getMemoryVT();
   SDLoc dl(Ld);
SDValue Ch1 = DAG.getStore(St->getChain(), dl, Value1, Ptr1,
                                 std::min(16U, Alignment));
     return DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Ch0, Ch1);
   }
 
   // Optimize trunc store (of multiple scalars) to shuffle and store.
   // First, pack all of the elements in one place. Next, store to memory
   // in fewer chunks.
   if (St->isTruncatingStore() && VT.isVector()) {
+    // Check if we can detect an AVG pattern from the truncation. If yes,
+    // replace the trunc store by a normal store with the result of X86ISD::AVG
+    // instruction.
+    SDValue Avg =
+        detectAVGPattern(St->getValue(), St->getMemoryVT(), DAG, Subtarget, dl);
+    if (Avg.getNode())
+      return DAG.getStore(St->getChain(), dl, Avg, St->getBasePtr(),
+                          St->getPointerInfo(), St->isVolatile(),
+                          St->isNonTemporal(), St->getAlignment());
+
     const TargetLowering &TLI = DAG.getTargetLoweringInfo();
     unsigned NumElems = VT.getVectorNumElements();
     assert(StVT != VT && "Cannot truncate to the same type");
     unsigned FromSz = VT.getVectorElementType().getSizeInBits();
     unsigned ToSz = StVT.getVectorElementType().getSizeInBits();
 
     // The truncating store is legal in some cases. For example
     // vpmovqb, vpmovqw, vpmovqd, vpmovdb, vpmovdw
SDValue X86TargetLowering::PerformDAGCombine(SDNode *N,
   case ISD::LOAD:           return PerformLOADCombine(N, DAG, DCI, Subtarget);
   case ISD::MLOAD:          return PerformMLOADCombine(N, DAG, DCI, Subtarget);
   case ISD::STORE:          return PerformSTORECombine(N, DAG, Subtarget);
   case ISD::MSTORE:         return PerformMSTORECombine(N, DAG, Subtarget);
   case ISD::SINT_TO_FP:     return PerformSINT_TO_FPCombine(N, DAG, Subtarget);
   case ISD::UINT_TO_FP:     return PerformUINT_TO_FPCombine(N, DAG, Subtarget);
   case ISD::FADD:           return PerformFADDCombine(N, DAG, Subtarget);
   case ISD::FSUB:           return PerformFSUBCombine(N, DAG, Subtarget);
+  case ISD::TRUNCATE:       return PerformTRUNCATECombine(N, DAG, Subtarget);
   case X86ISD::FXOR:
   case X86ISD::FOR:         return PerformFORCombine(N, DAG, Subtarget);
   case X86ISD::FMIN:
   case X86ISD::FMAX:        return PerformFMinFMaxCombine(N, DAG);
   case X86ISD::FAND:        return PerformFANDCombine(N, DAG);
   case X86ISD::FANDN:       return PerformFANDNCombine(N, DAG);
   case X86ISD::BT:          return PerformBTCombine(N, DAG, DCI);
   case X86ISD::VZEXT_MOVL:  return PerformVZEXT_MOVLCombine(N, DAG);

lib/Target/X86/X86InstrSSE.td

 defm PMINUB  : PDI_binop_all<0xDA, "pminub", umin, v16i8, v32i8,
                              SSE_INTALU_ITINS_P, 1, NoVLX_Or_NoBWI>;
 defm PMINSW  : PDI_binop_all<0xEA, "pminsw", smin, v8i16, v16i16,
                              SSE_INTALU_ITINS_P, 1, NoVLX_Or_NoBWI>;
 defm PMAXUB  : PDI_binop_all<0xDE, "pmaxub", umax, v16i8, v32i8,
                              SSE_INTALU_ITINS_P, 1, NoVLX_Or_NoBWI>;
 defm PMAXSW  : PDI_binop_all<0xEE, "pmaxsw", smax, v8i16, v16i16,
                              SSE_INTALU_ITINS_P, 1, NoVLX_Or_NoBWI>;
+defm PAVGB   : PDI_binop_all<0xE0, "pavgb", X86avg, v16i8, v32i8,
+                             SSE_INTALU_ITINS_P, 1, NoVLX_Or_NoBWI>;
+defm PAVGW   : PDI_binop_all<0xE3, "pavgw", X86avg, v8i16, v16i16,
+                             SSE_INTALU_ITINS_P, 1, NoVLX_Or_NoBWI>;
 
 // Intrinsic forms
 defm PSUBSB  : PDI_binop_all_int<0xE8, "psubsb", int_x86_sse2_psubs_b,
                                  int_x86_avx2_psubs_b, SSE_INTALU_ITINS_P, 0>;
 defm PSUBSW  : PDI_binop_all_int<0xE9, "psubsw" , int_x86_sse2_psubs_w,
                                  int_x86_avx2_psubs_w, SSE_INTALU_ITINS_P, 0>;
 defm PADDSB  : PDI_binop_all_int<0xEC, "paddsb" , int_x86_sse2_padds_b,
                                  int_x86_avx2_padds_b, SSE_INTALU_ITINS_P, 1>;
 defm PADDSW  : PDI_binop_all_int<0xED, "paddsw" , int_x86_sse2_padds_w,
                                  int_x86_avx2_padds_w, SSE_INTALU_ITINS_P, 1>;
 defm PADDUSB : PDI_binop_all_int<0xDC, "paddusb", int_x86_sse2_paddus_b,
                                  int_x86_avx2_paddus_b, SSE_INTALU_ITINS_P, 1>;
 defm PADDUSW : PDI_binop_all_int<0xDD, "paddusw", int_x86_sse2_paddus_w,
                                  int_x86_avx2_paddus_w, SSE_INTALU_ITINS_P, 1>;
 defm PMADDWD : PDI_binop_all_int<0xF5, "pmaddwd", int_x86_sse2_pmadd_wd,
                                  int_x86_avx2_pmadd_wd, SSE_PMADD, 1>;
-defm PAVGB   : PDI_binop_all_int<0xE0, "pavgb", int_x86_sse2_pavg_b,
-                                 int_x86_avx2_pavg_b, SSE_INTALU_ITINS_P, 1>;
-defm PAVGW   : PDI_binop_all_int<0xE3, "pavgw", int_x86_sse2_pavg_w,
-                                 int_x86_avx2_pavg_w, SSE_INTALU_ITINS_P, 1>;
 defm PSADBW  : PDI_binop_all_int<0xF6, "psadbw", int_x86_sse2_psad_bw,
                                  int_x86_avx2_psad_bw, SSE_PMADD, 1>;
 
 let Predicates = [HasAVX2] in
   def : Pat<(v32i8 (X86psadbw (v32i8 VR256:$src1),
                               (v32i8 VR256:$src2))),
             (VPSADBWYrr VR256:$src2, VR256:$src1)>;
 

lib/Target/X86/X86IntrinsicsInfo.h

  * IntrinsicsWithoutChain - the table should be sorted by Intrinsic ID - in
  * the alphabetical order.
  */
 static const IntrinsicData  IntrinsicsWithoutChain[] = {
   X86_INTRINSIC_DATA(avx2_packssdw, INTR_TYPE_2OP, X86ISD::PACKSS, 0),
   X86_INTRINSIC_DATA(avx2_packsswb, INTR_TYPE_2OP, X86ISD::PACKSS, 0),
   X86_INTRINSIC_DATA(avx2_packusdw, INTR_TYPE_2OP, X86ISD::PACKUS, 0),
   X86_INTRINSIC_DATA(avx2_packuswb, INTR_TYPE_2OP, X86ISD::PACKUS, 0),
+  X86_INTRINSIC_DATA(avx2_pavg_b,  INTR_TYPE_2OP, X86ISD::AVG, 0),
+  X86_INTRINSIC_DATA(avx2_pavg_w,  INTR_TYPE_2OP, X86ISD::AVG, 0),
   X86_INTRINSIC_DATA(avx2_phadd_d, INTR_TYPE_2OP, X86ISD::HADD, 0),
   X86_INTRINSIC_DATA(avx2_phadd_w, INTR_TYPE_2OP, X86ISD::HADD, 0),
   X86_INTRINSIC_DATA(avx2_phsub_d, INTR_TYPE_2OP, X86ISD::HSUB, 0),
   X86_INTRINSIC_DATA(avx2_phsub_w, INTR_TYPE_2OP, X86ISD::HSUB, 0),
   X86_INTRINSIC_DATA(avx2_pmaxs_b, INTR_TYPE_2OP, ISD::SMAX, 0),
   X86_INTRINSIC_DATA(avx2_pmaxs_d, INTR_TYPE_2OP, ISD::SMAX, 0),
   X86_INTRINSIC_DATA(avx2_pmaxs_w, INTR_TYPE_2OP, ISD::SMAX, 0),
   X86_INTRINSIC_DATA(avx2_pmaxu_b, INTR_TYPE_2OP, ISD::UMAX, 0),

   X86_INTRINSIC_DATA(sse2_comile_sd,    COMI, X86ISD::COMI, ISD::SETLE),
   X86_INTRINSIC_DATA(sse2_comilt_sd,    COMI, X86ISD::COMI, ISD::SETLT),
   X86_INTRINSIC_DATA(sse2_comineq_sd,   COMI, X86ISD::COMI, ISD::SETNE),
   X86_INTRINSIC_DATA(sse2_max_pd,       INTR_TYPE_2OP, X86ISD::FMAX, 0),
   X86_INTRINSIC_DATA(sse2_min_pd,       INTR_TYPE_2OP, X86ISD::FMIN, 0),
   X86_INTRINSIC_DATA(sse2_packssdw_128, INTR_TYPE_2OP, X86ISD::PACKSS, 0),
   X86_INTRINSIC_DATA(sse2_packsswb_128, INTR_TYPE_2OP, X86ISD::PACKSS, 0),
   X86_INTRINSIC_DATA(sse2_packuswb_128, INTR_TYPE_2OP, X86ISD::PACKUS, 0),
+  X86_INTRINSIC_DATA(sse2_pavg_b,       INTR_TYPE_2OP, X86ISD::AVG, 0),
+  X86_INTRINSIC_DATA(sse2_pavg_w,       INTR_TYPE_2OP, X86ISD::AVG, 0),
   X86_INTRINSIC_DATA(sse2_pmaxs_w,      INTR_TYPE_2OP, ISD::SMAX, 0),
   X86_INTRINSIC_DATA(sse2_pmaxu_b,      INTR_TYPE_2OP, ISD::UMAX, 0),
   X86_INTRINSIC_DATA(sse2_pmins_w,      INTR_TYPE_2OP, ISD::SMIN, 0),
   X86_INTRINSIC_DATA(sse2_pminu_b,      INTR_TYPE_2OP, ISD::UMIN, 0),
   X86_INTRINSIC_DATA(sse2_pmulh_w,      INTR_TYPE_2OP, ISD::MULHS, 0),
   X86_INTRINSIC_DATA(sse2_pmulhu_w,     INTR_TYPE_2OP, ISD::MULHU, 0),
   X86_INTRINSIC_DATA(sse2_pmulu_dq,     INTR_TYPE_2OP, X86ISD::PMULUDQ, 0),
   X86_INTRINSIC_DATA(sse2_pshuf_d,      INTR_TYPE_2OP, X86ISD::PSHUFD, 0),

test/CodeGen/X86/avg.ll

+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=x86-64 -mattr=+sse2 | FileCheck %s --check-prefix=SSE2
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=x86-64 -mattr=+avx2 | FileCheck %s --check-prefix=AVX2
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=x86-64 -mattr=+avx512bw | FileCheck %s --check-prefix=AVX2 --check-prefix=AVX512BW
+
+define void @avg_v4i8(<4 x i8>* %a, <4 x i8>* %b) {
+; SSE2-LABEL: avg_v4i8
+; SSE2:      # BB#0:
+; SSE2-NEXT: movd (%rdi), %xmm0           # xmm0 = mem[0],zero,zero,zero
+; SSE2-NEXT: movd (%rsi), %xmm1           # xmm1 = mem[0],zero,zero,zero
+; SSE2-NEXT: pavgb %xmm0, %xmm1
+; SSE2-NEXT: movd %xmm1, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v4i8
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovd (%rdi), %xmm0
+; AVX2-NEXT: vmovd (%rsi), %xmm1
+; AVX2-NEXT: vpavgb %xmm0, %xmm1, %xmm0
+; AVX2-NEXT: vmovd %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <4 x i8>, <4 x i8>* %a
+  %2 = load <4 x i8>, <4 x i8>* %b
+  %3 = zext <4 x i8> %1 to <4 x i32>
+  %4 = zext <4 x i8> %2 to <4 x i32>
+  %5 = add nuw nsw <4 x i32> %3, <i32 1, i32 1, i32 1, i32 1>
+  %6 = add nuw nsw <4 x i32> %5, %4
+  %7 = lshr <4 x i32> %6, <i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <4 x i32> %7 to <4 x i8>
+  store <4 x i8> %8, <4 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v8i8(<8 x i8>* %a, <8 x i8>* %b) {
+; SSE2-LABEL: avg_v8i8
+; SSE2:       # BB#0:
+; SSE2-NEXT: movq (%rdi), %xmm0           # xmm0 = mem[0],zero
+; SSE2-NEXT: movq (%rsi), %xmm1           # xmm1 = mem[0],zero
+; SSE2-NEXT: pavgb %xmm0, %xmm1
+; SSE2-NEXT: movq %xmm1, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v8i8
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovq (%rdi), %xmm0
+; AVX2-NEXT: vmovq (%rsi), %xmm1
+; AVX2-NEXT: vpavgb %xmm0, %xmm1, %xmm0
+; AVX2-NEXT: vmovq %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <8 x i8>, <8 x i8>* %a
+  %2 = load <8 x i8>, <8 x i8>* %b
+  %3 = zext <8 x i8> %1 to <8 x i32>
+  %4 = zext <8 x i8> %2 to <8 x i32>
+  %5 = add nuw nsw <8 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %6 = add nuw nsw <8 x i32> %5, %4
+  %7 = lshr <8 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <8 x i32> %7 to <8 x i8>
+  store <8 x i8> %8, <8 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v16i8(<16 x i8>* %a, <16 x i8>* %b) {
+; SSE2-LABEL: avg_v16i8
+; SSE2:       # BB#0:
+; SSE2-NEXT: movdqa (%rsi), %xmm0
+; SSE2-NEXT: pavgb (%rdi), %xmm0
+; SSE2-NEXT: movdqu %xmm0, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v16i8
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovdqa (%rsi), %xmm0
+; AVX2-NEXT: vpavgb (%rdi), %xmm0, %xmm0
+; AVX2-NEXT: vmovdqu %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <16 x i8>, <16 x i8>* %a
+  %2 = load <16 x i8>, <16 x i8>* %b
+  %3 = zext <16 x i8> %1 to <16 x i32>
+  %4 = zext <16 x i8> %2 to <16 x i32>
+  %5 = add nuw nsw <16 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %6 = add nuw nsw <16 x i32> %5, %4
+  %7 = lshr <16 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <16 x i32> %7 to <16 x i8>
+  store <16 x i8> %8, <16 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v32i8(<32 x i8>* %a, <32 x i8>* %b) {
+; AVX2-LABEL: avg_v32i8
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovdqa (%rsi), %ymm0
+; AVX2-NEXT: vpavgb (%rdi), %ymm0, %ymm0
+; AVX2-NEXT: vmovdqu %ymm0, (%rax)
+;
+  %1 = load <32 x i8>, <32 x i8>* %a
+  %2 = load <32 x i8>, <32 x i8>* %b
+  %3 = zext <32 x i8> %1 to <32 x i32>
+  %4 = zext <32 x i8> %2 to <32 x i32>
+  %5 = add nuw nsw <32 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %6 = add nuw nsw <32 x i32> %5, %4
+  %7 = lshr <32 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <32 x i32> %7 to <32 x i8>
+  store <32 x i8> %8, <32 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v64i8(<64 x i8>* %a, <64 x i8>* %b) {
+; AVX512BW-LABEL: avg_v64i8
+; AVX512BW: # BB#0:
+; AVX512BW-NEXT: vmovdqu8 (%rsi), %zmm0
+; AVX512BW-NEXT: vpavgb (%rdi), %zmm0, %zmm0
+; AVX512BW-NEXT: vmovdqu8 %zmm0, (%rax)
+; AVX512BW-NEXT: retq
+;
+  %1 = load <64 x i8>, <64 x i8>* %a
+  %2 = load <64 x i8>, <64 x i8>* %b
+  %3 = zext <64 x i8> %1 to <64 x i32>
+  %4 = zext <64 x i8> %2 to <64 x i32>
+  %5 = add nuw nsw <64 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %6 = add nuw nsw <64 x i32> %5, %4
+  %7 = lshr <64 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <64 x i32> %7 to <64 x i8>
+  store <64 x i8> %8, <64 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v4i16(<4 x i16>* %a, <4 x i16>* %b) {
+; SSE2-LABEL: avg_v4i16
+; SSE2:       # BB#0:
+; SSE2-NEXT: movq (%rdi), %xmm0           # xmm0 = mem[0],zero
+; SSE2-NEXT: movq (%rsi), %xmm1           # xmm1 = mem[0],zero
+; SSE2-NEXT: pavgw %xmm0, %xmm1
+; SSE2-NEXT: movq %xmm1, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v4i16
+; AVX2:      # BB#0:
+; AVX2-NEXT: vmovq (%rdi), %xmm0
+; AVX2-NEXT: vmovq (%rsi), %xmm1
+; AVX2-NEXT: vpavgw %xmm0, %xmm1, %xmm0
+; AVX2-NEXT: vmovq %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <4 x i16>, <4 x i16>* %a
+  %2 = load <4 x i16>, <4 x i16>* %b
+  %3 = zext <4 x i16> %1 to <4 x i32>
+  %4 = zext <4 x i16> %2 to <4 x i32>
+  %5 = add nuw nsw <4 x i32> %3, <i32 1, i32 1, i32 1, i32 1>
+  %6 = add nuw nsw <4 x i32> %5, %4
+  %7 = lshr <4 x i32> %6, <i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <4 x i32> %7 to <4 x i16>
+  store <4 x i16> %8, <4 x i16>* undef, align 4
+  ret void
+}
+
+define void @avg_v8i16(<8 x i16>* %a, <8 x i16>* %b) {
+; SSE2-LABEL: avg_v8i16
+; SSE2:       # BB#0:
+; SSE2-NEXT: movdqa (%rsi), %xmm0
+; SSE2-NEXT: pavgw (%rdi), %xmm0
+; SSE2-NEXT: movdqu %xmm0, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v8i16
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovdqa (%rsi), %xmm0
+; AVX2-NEXT: vpavgw (%rdi), %xmm0, %xmm0
+; AVX2-NEXT: vmovdqu %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <8 x i16>, <8 x i16>* %a
+  %2 = load <8 x i16>, <8 x i16>* %b
+  %3 = zext <8 x i16> %1 to <8 x i32>
+  %4 = zext <8 x i16> %2 to <8 x i32>
+  %5 = add nuw nsw <8 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %6 = add nuw nsw <8 x i32> %5, %4
+  %7 = lshr <8 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <8 x i32> %7 to <8 x i16>
+  store <8 x i16> %8, <8 x i16>* undef, align 4
+  ret void
+}
+
+define void @avg_v16i16(<16 x i16>* %a, <16 x i16>* %b) {
+; AVX2-LABEL: avg_v16i16
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovdqa (%rsi), %ymm0
+; AVX2-NEXT: vpavgw (%rdi), %ymm0, %ymm0
+; AVX2-NEXT: vmovdqu %ymm0, (%rax)
+;
+  %1 = load <16 x i16>, <16 x i16>* %a
+  %2 = load <16 x i16>, <16 x i16>* %b
+  %3 = zext <16 x i16> %1 to <16 x i32>
+  %4 = zext <16 x i16> %2 to <16 x i32>
+  %5 = add nuw nsw <16 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %6 = add nuw nsw <16 x i32> %5, %4
+  %7 = lshr <16 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <16 x i32> %7 to <16 x i16>
+  store <16 x i16> %8, <16 x i16>* undef, align 4
+  ret void
+}
+
+define void @avg_v32i16(<32 x i16>* %a, <32 x i16>* %b) {
+; AVX512BW-LABEL: avg_v32i16
+; AVX512BW:      # BB#0:
+; AVX512BW-NEXT: vmovdqu16 (%rsi), %zmm0
+; AVX512BW-NEXT: vpavgw (%rdi), %zmm0, %zmm0
+; AVX512BW-NEXT: vmovdqu16 %zmm0, (%rax)
+; AVX512BW-NEXT: retq
+;
+  %1 = load <32 x i16>, <32 x i16>* %a
+  %2 = load <32 x i16>, <32 x i16>* %b
+  %3 = zext <32 x i16> %1 to <32 x i32>
+  %4 = zext <32 x i16> %2 to <32 x i32>
+  %5 = add nuw nsw <32 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %6 = add nuw nsw <32 x i32> %5, %4
+  %7 = lshr <32 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <32 x i32> %7 to <32 x i16>
+  store <32 x i16> %8, <32 x i16>* undef, align 4
+  ret void
+}
+
+define void @avg_v4i8_2(<4 x i8>* %a, <4 x i8>* %b) {
+; SSE2-LABEL: avg_v4i8_2
+; SSE2:       # BB#0:
+; SSE2-NEXT:  movd (%rdi), %xmm0
+; SSE2-NEXT:  movd (%rsi), %xmm1
+; SSE2-NEXT:  pavgb %xmm0, %xmm1
+; SSE2-NEXT:  movd %xmm1, (%rax)
+; SSE2-NEXT:  retq
+;
+; AVX2-LABEL: avg_v4i8_2
+; AVX2:      # BB#0:
+; AVX2-NEXT: vmovd (%rdi), %xmm0
+; AVX2-NEXT: vmovd (%rsi), %xmm1
+; AVX2-NEXT: vpavgb %xmm1, %xmm0, %xmm0
+; AVX2-NEXT: vmovd %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <4 x i8>, <4 x i8>* %a
+  %2 = load <4 x i8>, <4 x i8>* %b
+  %3 = zext <4 x i8> %1 to <4 x i32>
+  %4 = zext <4 x i8> %2 to <4 x i32>
+  %5 = add nuw nsw <4 x i32> %3, %4
+  %6 = add nuw nsw <4 x i32> %5, <i32 1, i32 1, i32 1, i32 1>
+  %7 = lshr <4 x i32> %6, <i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <4 x i32> %7 to <4 x i8>
+  store <4 x i8> %8, <4 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v8i8_2(<8 x i8>* %a, <8 x i8>* %b) {
+; SSE2-LABEL: avg_v8i8_2
+; SSE2:       # BB#0:
+; SSE2-NEXT: movq (%rdi), %xmm0           # xmm0 = mem[0],zero
+; SSE2-NEXT: movq (%rsi), %xmm1           # xmm1 = mem[0],zero
+; SSE2-NEXT: pavgb %xmm0, %xmm1
+; SSE2-NEXT: movq %xmm1, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v8i8_2
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovq (%rdi), %xmm0
+; AVX2-NEXT: vmovq (%rsi), %xmm1
+; AVX2-NEXT: vpavgb %xmm1, %xmm0, %xmm0
+; AVX2-NEXT: vmovq %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <8 x i8>, <8 x i8>* %a
+  %2 = load <8 x i8>, <8 x i8>* %b
+  %3 = zext <8 x i8> %1 to <8 x i32>
+  %4 = zext <8 x i8> %2 to <8 x i32>
+  %5 = add nuw nsw <8 x i32> %3, %4
+  %6 = add nuw nsw <8 x i32> %5, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %7 = lshr <8 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <8 x i32> %7 to <8 x i8>
+  store <8 x i8> %8, <8 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v16i8_2(<16 x i8>* %a, <16 x i8>* %b) {
+; SSE2-LABEL: avg_v16i8_2
+; SSE2:       # BB#0:
+; SSE2-NEXT: movdqa (%rdi), %xmm0
+; SSE2-NEXT: pavgb (%rsi), %xmm0
+; SSE2-NEXT: movdqu %xmm0, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v16i8_2
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovdqa (%rdi), %xmm0
+; AVX2-NEXT: vpavgb (%rsi), %xmm0, %xmm0
+; AVX2-NEXT: vmovdqu %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <16 x i8>, <16 x i8>* %a
+  %2 = load <16 x i8>, <16 x i8>* %b
+  %3 = zext <16 x i8> %1 to <16 x i32>
+  %4 = zext <16 x i8> %2 to <16 x i32>
+  %5 = add nuw nsw <16 x i32> %3, %4
+  %6 = add nuw nsw <16 x i32> %5, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %7 = lshr <16 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <16 x i32> %7 to <16 x i8>
+  store <16 x i8> %8, <16 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v32i8_2(<32 x i8>* %a, <32 x i8>* %b) {
+; AVX2-LABEL: avg_v32i8_2
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovdqa (%rdi), %ymm0
+; AVX2-NEXT: vpavgb (%rsi), %ymm0, %ymm0
+; AVX2-NEXT: vmovdqu %ymm0, (%rax)
+;
+  %1 = load <32 x i8>, <32 x i8>* %a
+  %2 = load <32 x i8>, <32 x i8>* %b
+  %3 = zext <32 x i8> %1 to <32 x i32>
+  %4 = zext <32 x i8> %2 to <32 x i32>
+  %5 = add nuw nsw <32 x i32> %3, %4
+  %6 = add nuw nsw <32 x i32> %5, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %7 = lshr <32 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <32 x i32> %7 to <32 x i8>
+  store <32 x i8> %8, <32 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v64i8_2(<64 x i8>* %a, <64 x i8>* %b) {
+; AVX512BW-LABEL: avg_v64i8_2
+; AVX512BW:       # BB#0:
+; AVX512BW-NEXT: vmovdqu8 (%rsi), %zmm0
+; AVX512BW-NEXT: vpavgb %zmm0, %zmm0, %zmm0
+; AVX512BW-NEXT: vmovdqu8 %zmm0, (%rax)
+; AVX512BW-NEXT: retq
+;
+  %1 = load <64 x i8>, <64 x i8>* %a
+  %2 = load <64 x i8>, <64 x i8>* %b
+  %3 = zext <64 x i8> %1 to <64 x i32>
+  %4 = zext <64 x i8> %2 to <64 x i32>
+  %5 = add nuw nsw <64 x i32> %4, %4
+  %6 = add nuw nsw <64 x i32> %5, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %7 = lshr <64 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <64 x i32> %7 to <64 x i8>
+  store <64 x i8> %8, <64 x i8>* undef, align 4
+  ret void
+}
+
+
+define void @avg_v4i16_2(<4 x i16>* %a, <4 x i16>* %b) {
+; SSE2-LABEL: avg_v4i16_2
+; SSE2:       # BB#0:
+; SSE2-NEXT: movq (%rdi), %xmm0           # xmm0 = mem[0],zero
+; SSE2-NEXT: movq (%rsi), %xmm1           # xmm1 = mem[0],zero
+; SSE2-NEXT: pavgw %xmm0, %xmm1
+; SSE2-NEXT: movq %xmm1, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v4i16_2
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovq (%rdi), %xmm0
+; AVX2-NEXT: vmovq (%rsi), %xmm1
+; AVX2-NEXT: vpavgw %xmm1, %xmm0, %xmm0
+; AVX2-NEXT: vmovq %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <4 x i16>, <4 x i16>* %a
+  %2 = load <4 x i16>, <4 x i16>* %b
+  %3 = zext <4 x i16> %1 to <4 x i32>
+  %4 = zext <4 x i16> %2 to <4 x i32>
+  %5 = add nuw nsw <4 x i32> %3, %4
+  %6 = add nuw nsw <4 x i32> %5, <i32 1, i32 1, i32 1, i32 1>
+  %7 = lshr <4 x i32> %6, <i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <4 x i32> %7 to <4 x i16>
+  store <4 x i16> %8, <4 x i16>* undef, align 4
+  ret void
+}
+
+define void @avg_v8i16_2(<8 x i16>* %a, <8 x i16>* %b) {
+; SSE2-LABEL: avg_v8i16_2
+; SSE2:       # BB#0:
+; SSE2-NEXT:  movdqa (%rdi), %xmm0
+; SSE2-NEXT:  pavgw (%rsi), %xmm0
+; SSE2-NEXT:  movdqu %xmm0, (%rax)
+; SSE2-NEXT:  retq
+;
+; AVX2-LABEL: avg_v8i16_2
+; AVX2:      # BB#0:
+; AVX2-NEXT: vmovdqa (%rdi), %xmm0
+; AVX2-NEXT: vpavgw (%rsi), %xmm0, %xmm0
+; AVX2-NEXT: vmovdqu %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <8 x i16>, <8 x i16>* %a
+  %2 = load <8 x i16>, <8 x i16>* %b
+  %3 = zext <8 x i16> %1 to <8 x i32>
+  %4 = zext <8 x i16> %2 to <8 x i32>
+  %5 = add nuw nsw <8 x i32> %3, %4
+  %6 = add nuw nsw <8 x i32> %5, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %7 = lshr <8 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <8 x i32> %7 to <8 x i16>
+  store <8 x i16> %8, <8 x i16>* undef, align 4
+  ret void
+}
+
+define void @avg_v16i16_2(<16 x i16>* %a, <16 x i16>* %b) {
+; AVX2-LABEL: avg_v16i16_2
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovdqa (%rdi), %ymm0
+; AVX2-NEXT: vpavgw (%rsi), %ymm0, %ymm0
+; AVX2-NEXT: vmovdqu %ymm0, (%rax)
+;
+  %1 = load <16 x i16>, <16 x i16>* %a
+  %2 = load <16 x i16>, <16 x i16>* %b
+  %3 = zext <16 x i16> %1 to <16 x i32>
+  %4 = zext <16 x i16> %2 to <16 x i32>
+  %5 = add nuw nsw <16 x i32> %3, %4
+  %6 = add nuw nsw <16 x i32> %5, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %7 = lshr <16 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <16 x i32> %7 to <16 x i16>
+  store <16 x i16> %8, <16 x i16>* undef, align 4
+  ret void
+}
+
+define void @avg_v32i16_2(<32 x i16>* %a, <32 x i16>* %b) {
+; AVX512BW-LABEL: avg_v32i16_2
+; AVX512BW:       # BB#0:
+; AVX512BW-NEXT: vmovdqu16 (%rdi), %zmm0
+; AVX512BW-NEXT: vpavgw (%rsi), %zmm0, %zmm0
+; AVX512BW-NEXT: vmovdqu16 %zmm0, (%rax)
+; AVX512BW-NEXT: retq
+;
+  %1 = load <32 x i16>, <32 x i16>* %a
+  %2 = load <32 x i16>, <32 x i16>* %b
+  %3 = zext <32 x i16> %1 to <32 x i32>
+  %4 = zext <32 x i16> %2 to <32 x i32>
+  %5 = add nuw nsw <32 x i32> %3, %4
+  %6 = add nuw nsw <32 x i32> %5, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %7 = lshr <32 x i32> %6, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %8 = trunc <32 x i32> %7 to <32 x i16>
+  store <32 x i16> %8, <32 x i16>* undef, align 4
+  ret void
+}
+
+define void @avg_v4i8_const(<4 x i8>* %a) {
+; SSE2-LABEL: avg_v4i8_const
+; SSE2:       # BB#0:
+; SSE2-NEXT: movd (%rdi), %xmm0           # xmm0 = mem[0],zero,zero,zero
+; SSE2-NEXT: pavgb {{.*}}, %xmm0
+; SSE2-NEXT: movd %xmm0, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v4i8_const
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovd (%rdi), %xmm0
+; AVX2-NEXT: vpavgb {{.*}}, %xmm0, %xmm0
+; AVX2-NEXT: vmovd %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <4 x i8>, <4 x i8>* %a
+  %2 = zext <4 x i8> %1 to <4 x i32>
+  %3 = add nuw nsw <4 x i32> %2, <i32 1, i32 2, i32 3, i32 4>
+  %4 = lshr <4 x i32> %3, <i32 1, i32 1, i32 1, i32 1>
+  %5 = trunc <4 x i32> %4 to <4 x i8>
+  store <4 x i8> %5, <4 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v8i8_const(<8 x i8>* %a) {
+; SSE2-LABEL: avg_v8i8_const
+; SSE2:       # BB#0:
+; SSE2-NEXT: movq (%rdi), %xmm0           # xmm0 = mem[0],zero
+; SSE2-NEXT: pavgb {{.*}}, %xmm0
+; SSE2-NEXT: movq %xmm0, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v8i8_const
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovq (%rdi), %xmm0
+; AVX2-NEXT: vpavgb {{.*}}, %xmm0, %xmm0
+; AVX2-NEXT: vmovq %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <8 x i8>, <8 x i8>* %a
+  %2 = zext <8 x i8> %1 to <8 x i32>
+  %3 = add nuw nsw <8 x i32> %2, <i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8>
+  %4 = lshr <8 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %5 = trunc <8 x i32> %4 to <8 x i8>
+  store <8 x i8> %5, <8 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v16i8_const(<16 x i8>* %a) {
+; SSE2-LABEL: avg_v16i8_const
+; SSE2:       # BB#0:
+; SSE2-NEXT: movdqa (%rdi), %xmm0
+; SSE2-NEXT: pavgb {{.*}}, %xmm0
+; SSE2-NEXT: movdqu %xmm0, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v16i8_const
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovdqa (%rdi), %xmm0
+; AVX2-NEXT: vpavgb {{.*}}, %xmm0, %xmm0
+; AVX2-NEXT: vmovdqu %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <16 x i8>, <16 x i8>* %a
+  %2 = zext <16 x i8> %1 to <16 x i32>
+  %3 = add nuw nsw <16 x i32> %2, <i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8>
+  %4 = lshr <16 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %5 = trunc <16 x i32> %4 to <16 x i8>
+  store <16 x i8> %5, <16 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v32i8_const(<32 x i8>* %a) {
+; AVX2-LABEL: avg_v32i8_const
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovdqa (%rdi), %ymm0
+; AVX2-NEXT: vpavgb {{.*}}, %ymm0, %ymm0
+; AVX2-NEXT: vmovdqu %ymm0, (%rax)
+;
+  %1 = load <32 x i8>, <32 x i8>* %a
+  %2 = zext <32 x i8> %1 to <32 x i32>
+  %3 = add nuw nsw <32 x i32> %2, <i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8>
+  %4 = lshr <32 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1> 
+  %5 = trunc <32 x i32> %4 to <32 x i8>
+  store <32 x i8> %5, <32 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v64i8_const(<64 x i8>* %a) {
+; AVX512BW-LABEL: avg_v64i8_const
+; AVX512BW: # BB#0:
+; AVX512BW-NEXT: vmovdqu8 (%rdi), %zmm0
+; AVX512BW-NEXT: vpavgb {{.*}}, %zmm0, %zmm0
+; AVX512BW-NEXT: vmovdqu8 %zmm0, (%rax)
+; AVX512BW-NEXT: retq
+;
+  %1 = load <64 x i8>, <64 x i8>* %a
+  %2 = zext <64 x i8> %1 to <64 x i32>
+  %3 = add nuw nsw <64 x i32> %2, <i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8>
+  %4 = lshr <64 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1> 
+  %5 = trunc <64 x i32> %4 to <64 x i8>
+  store <64 x i8> %5, <64 x i8>* undef, align 4
+  ret void
+}
+
+define void @avg_v4i16_const(<4 x i16>* %a) {
+; SSE2-LABEL: avg_v4i16_const
+; SSE2:       # BB#0:
+; SSE2-NEXT: movq (%rdi), %xmm0
+; SSE2-NEXT: pavgw {{.*}}, %xmm0
+; SSE2-NEXT: movq %xmm0, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v4i16_const
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovq (%rdi), %xmm0
+; AVX2-NEXT: vpavgw {{.*}}, %xmm0, %xmm0
+; AVX2-NEXT: vmovq %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <4 x i16>, <4 x i16>* %a
+  %2 = zext <4 x i16> %1 to <4 x i32>
+  %3 = add nuw nsw <4 x i32> %2, <i32 1, i32 2, i32 3, i32 4>
+  %4 = lshr <4 x i32> %3, <i32 1, i32 1, i32 1, i32 1>
+  %5 = trunc <4 x i32> %4 to <4 x i16>
+  store <4 x i16> %5, <4 x i16>* undef, align 4
+  ret void
+}
+
+define void @avg_v8i16_const(<8 x i16>* %a) {
+; SSE2-LABEL: avg_v8i16_const
+; SSE2:       # BB#0:
+; SSE2-NEXT: movdqa (%rdi), %xmm0
+; SSE2-NEXT: pavgw {{.*}}, %xmm0
+; SSE2-NEXT: movdqu %xmm0, (%rax)
+; SSE2-NEXT: retq
+;
+; AVX2-LABEL: avg_v8i16_const
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovdqa (%rdi), %xmm0
+; AVX2-NEXT: vpavgw {{.*}}, %xmm0, %xmm0
+; AVX2-NEXT: vmovdqu %xmm0, (%rax)
+; AVX2-NEXT: retq
+;
+  %1 = load <8 x i16>, <8 x i16>* %a
+  %2 = zext <8 x i16> %1 to <8 x i32>
+  %3 = add nuw nsw <8 x i32> %2, <i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8>
+  %4 = lshr <8 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %5 = trunc <8 x i32> %4 to <8 x i16>
+  store <8 x i16> %5, <8 x i16>* undef, align 4
+  ret void
+}
+
+define void @avg_v16i16_const(<16 x i16>* %a) {
+; AVX2-LABEL: avg_v16i16_const
+; AVX2:       # BB#0:
+; AVX2-NEXT: vmovdqa (%rdi), %ymm0
+; AVX2-NEXT: vpavgw {{.*}}, %ymm0, %ymm0
+; AVX2-NEXT: vmovdqu %ymm0, (%rax)
+;
+  %1 = load <16 x i16>, <16 x i16>* %a
+  %2 = zext <16 x i16> %1 to <16 x i32>
+  %3 = add nuw nsw <16 x i32> %2, <i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8>
+  %4 = lshr <16 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+  %5 = trunc <16 x i32> %4 to <16 x i16>
+  store <16 x i16> %5, <16 x i16>* undef, align 4
+  ret void
+}
+
+define void @avg_v32i16_const(<32 x i16>* %a) {
+; AVX512BW-LABEL: avg_v32i16_const
+; AVX512BW:       # BB#0:
+; AVX512BW-NEXT: vmovdqu16 (%rdi), %zmm0
+; AVX512BW-NEXT: vpavgw {{.*}}, %zmm0, %zmm0
+; AVX512BW-NEXT: vmovdqu16 %zmm0, (%rax)
+;
+  %1 = load <32 x i16>, <32 x i16>* %a
+  %2 = zext <32 x i16> %1 to <32 x i32>
+  %3 = add nuw nsw <32 x i32> %2, <i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8>
+  %4 = lshr <32 x i32> %3, <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1> 
+  %5 = trunc <32 x i32> %4 to <32 x i16>
+  store <32 x i16> %5, <32 x i16>* undef, align 4
+  ret void
+}