[x86] Teach the vector comment parsing and printing to correctly handle

undef in the shuffle mask. This shows up when we're printing comments
during lowering and we still have an IR-level constant hanging around
that models undef.

A nice consequence of this is *much* prettier test cases where the undef
lanes actually show up as undef rather than as a particular set of
values. This also allows us to print shuffle comments in cases that use
undef such as the recently added variable VPERMILPS lowering. Now those
test cases have nice shuffle comments attached with their details.

The shuffle lowering for PSHUFB has been augmented to use undef, and the
shuffle combining has been augmented to comprehend it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218301 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/InstPrinter/X86InstComments.cpp

@@ -628,14 +628,16 @@ bool llvm::EmitAnyX86InstComments(const MCInst *MI, raw_ostream &OS,
     const char *SrcName = isSrc1 ? Src1Name : Src2Name;
     OS << (SrcName ? SrcName : "mem") << '[';
     bool IsFirst = true;
-    while (i != e &&
+    while (i != e && (int)ShuffleMask[i] != SM_SentinelZero &&
-           (int)ShuffleMask[i] >= 0 &&
            (ShuffleMask[i] < (int)ShuffleMask.size()) == isSrc1) {
       if (!IsFirst)
         OS << ',';
       else
         IsFirst = false;
-      OS << ShuffleMask[i] % ShuffleMask.size();
+      if (ShuffleMask[i] == SM_SentinelUndef)
+        OS << "u";
+      else
+        OS << ShuffleMask[i] % ShuffleMask.size();
       ++i;
     }
     OS << ']';

lib/Target/X86/Utils/X86ShuffleDecode.cpp

@@ -224,8 +224,7 @@ void DecodeVPERM2X128Mask(MVT VT, unsigned Imm,
   }
 }
 
-void DecodePSHUFBMask(const ConstantDataSequential *C,
+void DecodePSHUFBMask(const Constant *C, SmallVectorImpl<int> &ShuffleMask) {
-                      SmallVectorImpl<int> &ShuffleMask) {
   Type *MaskTy = C->getType();
   assert(MaskTy->isVectorTy() && "Expected a vector constant mask!");
   assert(MaskTy->getVectorElementType()->isIntegerTy(8) &&
@@ -234,22 +233,48 @@ void DecodePSHUFBMask(const ConstantDataSequential *C,
   // FIXME: Add support for AVX-512.
   assert((NumElements == 16 || NumElements == 32) &&
          "Only 128-bit and 256-bit vectors supported!");
-  assert((unsigned)NumElements == C->getNumElements() &&
-         "Constant mask has a different number of elements!");
-
   ShuffleMask.reserve(NumElements);
-  for (int i = 0; i < NumElements; ++i) {
+
-    // For AVX vectors with 32 bytes the base of the shuffle is the half of the
+  if (auto *CDS = dyn_cast<ConstantDataSequential>(C)) {
-    // vector we're inside.
+    assert((unsigned)NumElements == CDS->getNumElements() &&
-    int Base = i < 16 ? 0 : 16;
+           "Constant mask has a different number of elements!");
-    uint64_t Element = C->getElementAsInteger(i);
+
-    // If the high bit (7) of the byte is set, the element is zeroed.
+    for (int i = 0; i < NumElements; ++i) {
-    if (Element & (1 << 7))
+      // For AVX vectors with 32 bytes the base of the shuffle is the 16-byte
-      ShuffleMask.push_back(SM_SentinelZero);
+      // lane of the vector we're inside.
-    else {
+      int Base = i < 16 ? 0 : 16;
-      // Only the least significant 4 bits of the byte are used.
+      uint64_t Element = CDS->getElementAsInteger(i);
-      int Index = Base + (Element & 0xf);
+      // If the high bit (7) of the byte is set, the element is zeroed.
-      ShuffleMask.push_back(Index);
+      if (Element & (1 << 7))
+        ShuffleMask.push_back(SM_SentinelZero);
+      else {
+        // Only the least significant 4 bits of the byte are used.
+        int Index = Base + (Element & 0xf);
+        ShuffleMask.push_back(Index);
+      }
+    }
+  } else if (auto *CV = dyn_cast<ConstantVector>(C)) {
+    assert((unsigned)NumElements == CV->getNumOperands() &&
+           "Constant mask has a different number of elements!");
+
+    for (int i = 0; i < NumElements; ++i) {
+      // For AVX vectors with 32 bytes the base of the shuffle is the 16-byte
+      // lane of the vector we're inside.
+      int Base = i < 16 ? 0 : 16;
+      Constant *COp = CV->getOperand(i);
+      if (isa<UndefValue>(COp)) {
+        ShuffleMask.push_back(SM_SentinelUndef);
+        continue;
+      }
+      uint64_t Element = cast<ConstantInt>(COp)->getZExtValue();
+      // If the high bit (7) of the byte is set, the element is zeroed.
+      if (Element & (1 << 7))
+        ShuffleMask.push_back(SM_SentinelZero);
+      else {
+        // Only the least significant 4 bits of the byte are used.
+        int Index = Base + (Element & 0xf);
+        ShuffleMask.push_back(Index);
+      }
     }
   }
 }
@@ -258,6 +283,10 @@ void DecodePSHUFBMask(ArrayRef<uint64_t> RawMask,
                       SmallVectorImpl<int> &ShuffleMask) {
   for (int i = 0, e = RawMask.size(); i < e; ++i) {
     uint64_t M = RawMask[i];
+    if (M == (uint64_t)SM_SentinelUndef) {
+      ShuffleMask.push_back(M);
+      continue;
+    }
     // For AVX vectors with 32 bytes the base of the shuffle is the half of
     // the vector we're inside.
     int Base = i < 16 ? 0 : 16;
@@ -287,8 +316,7 @@ void DecodeVPERMMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask) {
   }
 }
 
-void DecodeVPERMILPMask(const ConstantDataSequential *C,
+void DecodeVPERMILPMask(const Constant *C, SmallVectorImpl<int> &ShuffleMask) {
-                        SmallVectorImpl<int> &ShuffleMask) {
   Type *MaskTy = C->getType();
   assert(MaskTy->isVectorTy() && "Expected a vector constant mask!");
   assert(MaskTy->getVectorElementType()->isIntegerTy() &&
@@ -297,16 +325,34 @@ void DecodeVPERMILPMask(const ConstantDataSequential *C,
   int NumElements = MaskTy->getVectorNumElements();
   assert((NumElements == 2 || NumElements == 4 || NumElements == 8) &&
          "Unexpected number of vector elements.");
-  assert((unsigned)NumElements == C->getNumElements() &&
-         "Constant mask has a different number of elements!");
-
   ShuffleMask.reserve(NumElements);
-  for (int i = 0; i < NumElements; ++i) {
+  if (auto *CDS = dyn_cast<ConstantDataSequential>(C)) {
-    int Base = (i * ElementBits / 128) * (128 / ElementBits);
+    assert((unsigned)NumElements == CDS->getNumElements() &&
-    uint64_t Element = C->getElementAsInteger(i);
+           "Constant mask has a different number of elements!");
-    // Only the least significant 2 bits of the integer are used.
+
-    int Index = Base + (Element & 0x3);
+    for (int i = 0; i < NumElements; ++i) {
-    ShuffleMask.push_back(Index);
+      int Base = (i * ElementBits / 128) * (128 / ElementBits);
+      uint64_t Element = CDS->getElementAsInteger(i);
+      // Only the least significant 2 bits of the integer are used.
+      int Index = Base + (Element & 0x3);
+      ShuffleMask.push_back(Index);
+    }
+  } else if (auto *CV = dyn_cast<ConstantVector>(C)) {
+    assert((unsigned)NumElements == C->getNumOperands() &&
+           "Constant mask has a different number of elements!");
+
+    for (int i = 0; i < NumElements; ++i) {
+      int Base = (i * ElementBits / 128) * (128 / ElementBits);
+      Constant *COp = CV->getOperand(i);
+      if (isa<UndefValue>(COp)) {
+        ShuffleMask.push_back(SM_SentinelUndef);
+        continue;
+      }
+      uint64_t Element = cast<ConstantInt>(COp)->getZExtValue();
+      // Only the least significant 2 bits of the integer are used.
+      int Index = Base + (Element & 0x3);
+      ShuffleMask.push_back(Index);
+    }
   }
 }
 

lib/Target/X86/Utils/X86ShuffleDecode.h

@@ -23,12 +23,10 @@
 //===----------------------------------------------------------------------===//
 
 namespace llvm {
-class ConstantDataSequential;
+class Constant;
 class MVT;
 
-enum {
+enum { SM_SentinelZero = -1, SM_SentinelUndef = -2 };
-  SM_SentinelZero = -1
-};
 
 void DecodeINSERTPSMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask);
 
@@ -66,8 +64,7 @@ void DecodeUNPCKHMask(MVT VT, SmallVectorImpl<int> &ShuffleMask);
 void DecodeUNPCKLMask(MVT VT, SmallVectorImpl<int> &ShuffleMask);
 
 /// \brief Decode a PSHUFB mask from an IR-level vector constant.
-void DecodePSHUFBMask(const ConstantDataSequential *C,
+void DecodePSHUFBMask(const Constant *C, SmallVectorImpl<int> &ShuffleMask);
-                      SmallVectorImpl<int> &ShuffleMask);
 
 /// \brief Decode a PSHUFB mask from a raw array of constants such as from
 /// BUILD_VECTOR.
@@ -85,8 +82,7 @@ void DecodeVPERM2X128Mask(MVT VT, unsigned Imm,
 void DecodeVPERMMask(unsigned Imm, SmallVectorImpl<int> &ShuffleMask);
 
 /// \brief Decode a VPERMILP variable mask from an IR-level vector constant.
-void DecodeVPERMILPMask(const ConstantDataSequential *C,
+void DecodeVPERMILPMask(const Constant *C, SmallVectorImpl<int> &ShuffleMask);
-                        SmallVectorImpl<int> &ShuffleMask);
 
 } // llvm namespace
 

lib/Target/X86/X86ISelLowering.cpp

@@ -5347,7 +5347,12 @@ static bool getTargetShuffleMask(SDNode *N, MVT VT,
 
       SmallVector<uint64_t, 32> RawMask;
       for (int i = 0, e = MaskNode->getNumOperands(); i < e; ++i) {
-        auto *CN = dyn_cast<ConstantSDNode>(MaskNode->getOperand(i));
+        SDValue Op = MaskNode->getOperand(i);
+        if (Op->getOpcode() == ISD::UNDEF) {
+          RawMask.push_back((uint64_t)SM_SentinelUndef);
+          continue;
+        }
+        auto *CN = dyn_cast<ConstantSDNode>(Op.getNode());
         if (!CN)
           return false;
         APInt MaskElement = CN->getAPIntValue();
@@ -5377,13 +5382,13 @@ static bool getTargetShuffleMask(SDNode *N, MVT VT,
     if (!MaskCP || MaskCP->isMachineConstantPoolEntry())
       return false;
 
-    if (auto *C = dyn_cast<ConstantDataSequential>(MaskCP->getConstVal())) {
+    if (auto *C = dyn_cast<Constant>(MaskCP->getConstVal())) {
       // FIXME: Support AVX-512 here.
-      if (!C->getType()->isVectorTy() ||
+      Type *Ty = C->getType();
-          (C->getNumElements() != 16 && C->getNumElements() != 32))
+      if (!Ty->isVectorTy() || (Ty->getVectorNumElements() != 16 &&
+                                Ty->getVectorNumElements() != 32))
         return false;
 
-      assert(C->getType()->isVectorTy() && "Expected a vector constant.");
       DecodePSHUFBMask(C, Mask);
       break;
     }
@@ -8994,7 +8999,7 @@ static SDValue lowerV16I8VectorShuffle(SDValue Op, SDValue V1, SDValue V2,
     SDValue V2Mask[16];
     for (int i = 0; i < 16; ++i)
       if (Mask[i] == -1) {
-        V1Mask[i] = V2Mask[i] = DAG.getConstant(0x80, MVT::i8);
+        V1Mask[i] = V2Mask[i] = DAG.getUNDEF(MVT::i8);
       } else {
         V1Mask[i] = DAG.getConstant(Mask[i] < 16 ? Mask[i] : 0x80, MVT::i8);
         V2Mask[i] =
@@ -20167,6 +20172,10 @@ static bool combineX86ShuffleChain(SDValue Op, SDValue Root, ArrayRef<int> Mask,
     assert(Mask.size() <= 16 && "Can't shuffle elements smaller than bytes!");
     int Ratio = 16 / Mask.size();
     for (unsigned i = 0; i < 16; ++i) {
+      if (Mask[i / Ratio] == SM_SentinelUndef) {
+        PSHUFBMask.push_back(DAG.getUNDEF(MVT::i8));
+        continue;
+      }
       int M = Mask[i / Ratio] != SM_SentinelZero
                   ? Ratio * Mask[i / Ratio] + i % Ratio
                   : 255;
@@ -20277,17 +20286,18 @@ static bool combineX86ShufflesRecursively(SDValue Op, SDValue Root,
   // for this order is that we are recursing up the operation chain.
   for (int i = 0, e = std::max(OpMask.size(), RootMask.size()); i < e; ++i) {
     int RootIdx = i / RootRatio;
-    if (RootMask[RootIdx] == SM_SentinelZero) {
+    if (RootMask[RootIdx] < 0) {
-      // This is a zero-ed lane, we're done.
+      // This is a zero or undef lane, we're done.
-      Mask.push_back(SM_SentinelZero);
+      Mask.push_back(RootMask[RootIdx]);
       continue;
     }
 
     int RootMaskedIdx = RootMask[RootIdx] * RootRatio + i % RootRatio;
     int OpIdx = RootMaskedIdx / OpRatio;
-    if (OpMask[OpIdx] == SM_SentinelZero) {
+    if (OpMask[OpIdx] < 0) {
-      // The incoming lanes are zero, it doesn't matter which ones we are using.
+      // The incoming lanes are zero or undef, it doesn't matter which ones we
-      Mask.push_back(SM_SentinelZero);
+      // are using.
+      Mask.push_back(OpMask[OpIdx]);
       continue;
     }
 

lib/Target/X86/X86MCInstLower.cpp

@@ -1060,8 +1060,7 @@ void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) {
       Type *MaskTy = MaskConstantEntry.getType();
       (void)MaskTy;
       if (!MaskConstantEntry.isMachineConstantPoolEntry())
-        if (auto *C = dyn_cast<ConstantDataSequential>(
+        if (auto *C = dyn_cast<Constant>(MaskConstantEntry.Val.ConstVal)) {
-                MaskConstantEntry.Val.ConstVal)) {
           assert(MaskTy == C->getType() &&
                  "Expected a constant of the same type!");
 
@@ -1077,8 +1076,9 @@ void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) {
             DecodeVPERMILPMask(C, Mask);
           }
 
-          assert(Mask.size() == MaskTy->getVectorNumElements() &&
+          assert(
-                 "Shuffle mask has a different size than its type!");
+              (Mask.empty() || Mask.size() == MaskTy->getVectorNumElements()) &&
+              "Shuffle mask has a different size than its type!");
         }
     }
 
@@ -1104,7 +1104,10 @@ void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) {
             InSrc = true;
             CS << SrcName << "[";
           }
-          CS << M;
+          if (M == SM_SentinelUndef)
+            CS << "u";
+          else
+            CS << M;
         }
       }
       if (InSrc)

test/CodeGen/X86/vector-shuffle-128-v16.ll

@@ -301,12 +301,12 @@ define <16 x i8> @trunc_v4i32_shuffle(<16 x i8> %a) {
 ;
 ; SSSE3-LABEL: @trunc_v4i32_shuffle
 ; SSSE3:       # BB#0:
-; SSSE3-NEXT:    pshufb {{.*}} # xmm0 = xmm0[0,4,8,12],zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero
+; SSSE3-NEXT:    pshufb {{.*}} # xmm0 = xmm0[0,4,8,12,u,u,u,u,u,u,u,u,u,u,u,u]
 ; SSSE3-NEXT:    retq
 ;
 ; SSE41-LABEL: @trunc_v4i32_shuffle
 ; SSE41:       # BB#0:
-; SSE41-NEXT:    pshufb {{.*}} # xmm0 = xmm0[0,4,8,12],zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero
+; SSE41-NEXT:    pshufb {{.*}} # xmm0 = xmm0[0,4,8,12,u,u,u,u,u,u,u,u,u,u,u,u]
 ; SSE41-NEXT:    retq
   %shuffle = shufflevector <16 x i8> %a, <16 x i8> undef, <16 x i32> <i32 0, i32 4, i32 8, i32 12, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef>
   ret <16 x i8> %shuffle

test/CodeGen/X86/vector-shuffle-256-v8.ll

@@ -498,7 +498,7 @@ define <8 x float> @shuffle_v8f32_01235466(<8 x float> %a, <8 x float> %b) {
 define <8 x float> @shuffle_v8f32_002u6u44(<8 x float> %a, <8 x float> %b) {
 ; ALL-LABEL: @shuffle_v8f32_002u6u44
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[0,0,2,u,6,u,4,4]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x float> %a, <8 x float> %b, <8 x i32> <i32 0, i32 0, i32 2, i32 undef, i32 6, i32 undef, i32 4, i32 4>
   ret <8 x float> %shuffle
@@ -507,7 +507,7 @@ define <8 x float> @shuffle_v8f32_002u6u44(<8 x float> %a, <8 x float> %b) {
 define <8 x float> @shuffle_v8f32_00uu66uu(<8 x float> %a, <8 x float> %b) {
 ; ALL-LABEL: @shuffle_v8f32_00uu66uu
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[0,0,u,u,6,6,u,u]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x float> %a, <8 x float> %b, <8 x i32> <i32 0, i32 0, i32 undef, i32 undef, i32 6, i32 6, i32 undef, i32 undef>
   ret <8 x float> %shuffle
@@ -516,7 +516,7 @@ define <8 x float> @shuffle_v8f32_00uu66uu(<8 x float> %a, <8 x float> %b) {
 define <8 x float> @shuffle_v8f32_103245uu(<8 x float> %a, <8 x float> %b) {
 ; ALL-LABEL: @shuffle_v8f32_103245uu
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[1,0,3,2,4,5,u,u]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x float> %a, <8 x float> %b, <8 x i32> <i32 1, i32 0, i32 3, i32 2, i32 4, i32 5, i32 undef, i32 undef>
   ret <8 x float> %shuffle
@@ -525,7 +525,7 @@ define <8 x float> @shuffle_v8f32_103245uu(<8 x float> %a, <8 x float> %b) {
 define <8 x float> @shuffle_v8f32_1133uu67(<8 x float> %a, <8 x float> %b) {
 ; ALL-LABEL: @shuffle_v8f32_1133uu67
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[1,1,3,3,u,u,6,7]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x float> %a, <8 x float> %b, <8 x i32> <i32 1, i32 1, i32 3, i32 3, i32 undef, i32 undef, i32 6, i32 7>
   ret <8 x float> %shuffle
@@ -534,7 +534,7 @@ define <8 x float> @shuffle_v8f32_1133uu67(<8 x float> %a, <8 x float> %b) {
 define <8 x float> @shuffle_v8f32_0uu354uu(<8 x float> %a, <8 x float> %b) {
 ; ALL-LABEL: @shuffle_v8f32_0uu354uu
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[0,u,u,3,5,4,u,u]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x float> %a, <8 x float> %b, <8 x i32> <i32 0, i32 undef, i32 undef, i32 3, i32 5, i32 4, i32 undef, i32 undef>
   ret <8 x float> %shuffle
@@ -543,7 +543,7 @@ define <8 x float> @shuffle_v8f32_0uu354uu(<8 x float> %a, <8 x float> %b) {
 define <8 x float> @shuffle_v8f32_uuu3uu66(<8 x float> %a, <8 x float> %b) {
 ; ALL-LABEL: @shuffle_v8f32_uuu3uu66
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[u,u,u,3,u,u,6,6]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x float> %a, <8 x float> %b, <8 x i32> <i32 undef, i32 undef, i32 undef, i32 3, i32 undef, i32 undef, i32 6, i32 6>
   ret <8 x float> %shuffle
@@ -1044,7 +1044,7 @@ define <8 x i32> @shuffle_v8i32_01235466(<8 x i32> %a, <8 x i32> %b) {
 define <8 x i32> @shuffle_v8i32_002u6u44(<8 x i32> %a, <8 x i32> %b) {
 ; ALL-LABEL: @shuffle_v8i32_002u6u44
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[0,0,2,u,6,u,4,4]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x i32> %a, <8 x i32> %b, <8 x i32> <i32 0, i32 0, i32 2, i32 undef, i32 6, i32 undef, i32 4, i32 4>
   ret <8 x i32> %shuffle
@@ -1053,7 +1053,7 @@ define <8 x i32> @shuffle_v8i32_002u6u44(<8 x i32> %a, <8 x i32> %b) {
 define <8 x i32> @shuffle_v8i32_00uu66uu(<8 x i32> %a, <8 x i32> %b) {
 ; ALL-LABEL: @shuffle_v8i32_00uu66uu
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[0,0,u,u,6,6,u,u]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x i32> %a, <8 x i32> %b, <8 x i32> <i32 0, i32 0, i32 undef, i32 undef, i32 6, i32 6, i32 undef, i32 undef>
   ret <8 x i32> %shuffle
@@ -1062,7 +1062,7 @@ define <8 x i32> @shuffle_v8i32_00uu66uu(<8 x i32> %a, <8 x i32> %b) {
 define <8 x i32> @shuffle_v8i32_103245uu(<8 x i32> %a, <8 x i32> %b) {
 ; ALL-LABEL: @shuffle_v8i32_103245uu
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[1,0,3,2,4,5,u,u]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x i32> %a, <8 x i32> %b, <8 x i32> <i32 1, i32 0, i32 3, i32 2, i32 4, i32 5, i32 undef, i32 undef>
   ret <8 x i32> %shuffle
@@ -1071,7 +1071,7 @@ define <8 x i32> @shuffle_v8i32_103245uu(<8 x i32> %a, <8 x i32> %b) {
 define <8 x i32> @shuffle_v8i32_1133uu67(<8 x i32> %a, <8 x i32> %b) {
 ; ALL-LABEL: @shuffle_v8i32_1133uu67
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[1,1,3,3,u,u,6,7]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x i32> %a, <8 x i32> %b, <8 x i32> <i32 1, i32 1, i32 3, i32 3, i32 undef, i32 undef, i32 6, i32 7>
   ret <8 x i32> %shuffle
@@ -1080,7 +1080,7 @@ define <8 x i32> @shuffle_v8i32_1133uu67(<8 x i32> %a, <8 x i32> %b) {
 define <8 x i32> @shuffle_v8i32_0uu354uu(<8 x i32> %a, <8 x i32> %b) {
 ; ALL-LABEL: @shuffle_v8i32_0uu354uu
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[0,u,u,3,5,4,u,u]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x i32> %a, <8 x i32> %b, <8 x i32> <i32 0, i32 undef, i32 undef, i32 3, i32 5, i32 4, i32 undef, i32 undef>
   ret <8 x i32> %shuffle
@@ -1089,7 +1089,7 @@ define <8 x i32> @shuffle_v8i32_0uu354uu(<8 x i32> %a, <8 x i32> %b) {
 define <8 x i32> @shuffle_v8i32_uuu3uu66(<8 x i32> %a, <8 x i32> %b) {
 ; ALL-LABEL: @shuffle_v8i32_uuu3uu66
 ; ALL:       # BB#0:
-; ALL-NEXT:    vpermilps {{.*}}, %ymm0, %ymm0
+; ALL-NEXT:    vpermilps {{.*}} # ymm0 = ymm0[u,u,u,3,u,u,6,6]
 ; ALL-NEXT:    retq
   %shuffle = shufflevector <8 x i32> %a, <8 x i32> %b, <8 x i32> <i32 undef, i32 undef, i32 undef, i32 3, i32 undef, i32 undef, i32 6, i32 6>
   ret <8 x i32> %shuffle