Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -22750,6 +22750,41 @@
     Mask = getPSHUFShuffleMask(N);
     assert(Mask.size() == 4);
     break;
+  case X86ISD::UNPCKL: {
+    // Combine X86ISD::UNPCKL and ISD::VECTOR_SHUFFLE into X86ISD::UNPCKH, in
+    // which X86ISD::UNPCKL has a ISD::UNDEF operand, and ISD::VECTOR_SHUFFLE
+    // moves upper half elements into the lower half part. For example:
+    //
+    // t2: v16i8 = vector_shuffle<8,9,10,11,12,13,14,15,u,u,u,u,u,u,u,u> t1,
+    //     undef:v16i8
+    // t3: v16i8 = X86ISD::UNPCKL undef:v16i8, t2
+    //
+    // will be combined to:
+    //
+    // t3: v16i8 = X86ISD::UNPCKH undef:v16i8, t1
+
+    // This is only for 128-bit vectors. From SSE4.1 onward this combine may not
+    // happen due to advanced instructions.
+    if (!VT.is128BitVector())
+      return SDValue();
+
+    auto Op0 = N.getOperand(0);
+    auto Op1 = N.getOperand(1);
+    if (Op0.getOpcode() == ISD::UNDEF &&
+        Op1.getNode()->getOpcode() == ISD::VECTOR_SHUFFLE) {
+      ArrayRef<int> Mask = cast<ShuffleVectorSDNode>(Op1.getNode())->getMask();
+
+      unsigned NumElts = VT.getVectorNumElements();
+      SmallVector<int, 8> ExpectedMask(NumElts, -1);
+      std::iota(ExpectedMask.begin(), ExpectedMask.begin() + NumElts / 2,
+                NumElts / 2);
+
+      auto ShufOp = Op1.getNode()->getOperand(0);
+      if (isShuffleEquivalent(Op1, ShufOp, Mask, ExpectedMask))
+        return DAG.getNode(X86ISD::UNPCKH, DL, VT, N.getOperand(0), ShufOp);
+    }
+    return SDValue();
+  }
   default:
     return SDValue();
   }
Index: test/CodeGen/X86/vec_int_to_fp.ll
===================================================================
--- test/CodeGen/X86/vec_int_to_fp.ll
+++ test/CodeGen/X86/vec_int_to_fp.ll
@@ -1035,8 +1035,7 @@
 ; SSE-NEXT:    punpcklwd {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3]
 ; SSE-NEXT:    psrad $16, %xmm1
 ; SSE-NEXT:    cvtdq2ps %xmm1, %xmm2
-; SSE-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[2,3,0,1]
-; SSE-NEXT:    punpcklwd {{.*#+}} xmm0 = xmm0[0,0,1,1,2,2,3,3]
+; SSE-NEXT:    punpckhwd {{.*#+}} xmm0 = xmm0[4,4,5,5,6,6,7,7]
 ; SSE-NEXT:    psrad $16, %xmm0
 ; SSE-NEXT:    cvtdq2ps %xmm0, %xmm1
 ; SSE-NEXT:    movaps %xmm2, %xmm0
@@ -1820,15 +1819,14 @@
 ; SSE:       # BB#0:
 ; SSE-NEXT:    movq 24(%rdi), %rax
 ; SSE-NEXT:    movdqu 8(%rdi), %xmm0
-; SSE-NEXT:    pshufd {{.*#+}} xmm1 = xmm0[2,3,0,1]
-; SSE-NEXT:    punpcklwd {{.*#+}} xmm1 = xmm1[0,0,1,1,2,2,3,3]
+; SSE-NEXT:    punpcklwd {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3]
 ; SSE-NEXT:    psrad $16, %xmm1
 ; SSE-NEXT:    cvtdq2ps %xmm1, %xmm1
-; SSE-NEXT:    punpcklwd {{.*#+}} xmm0 = xmm0[0,0,1,1,2,2,3,3]
+; SSE-NEXT:    punpckhwd {{.*#+}} xmm0 = xmm0[4,4,5,5,6,6,7,7]
 ; SSE-NEXT:    psrad $16, %xmm0
 ; SSE-NEXT:    cvtdq2ps %xmm0, %xmm0
-; SSE-NEXT:    movaps %xmm0, (%rax)
-; SSE-NEXT:    movaps %xmm1, 16(%rax)
+; SSE-NEXT:    movaps %xmm0, 16(%rax)
+; SSE-NEXT:    movaps %xmm1, (%rax)
 ; SSE-NEXT:    retq
 ;
 ; AVX1-LABEL: aggregate_sitofp_8i16_to_8f32:
Index: test/CodeGen/X86/vector-sext.ll
===================================================================
--- test/CodeGen/X86/vector-sext.ll
+++ test/CodeGen/X86/vector-sext.ll
@@ -45,8 +45,7 @@
 ; SSE2:       # BB#0: # %entry
 ; SSE2-NEXT:    punpcklbw {{.*#+}} xmm2 = xmm2[0],xmm0[0],xmm2[1],xmm0[1],xmm2[2],xmm0[2],xmm2[3],xmm0[3],xmm2[4],xmm0[4],xmm2[5],xmm0[5],xmm2[6],xmm0[6],xmm2[7],xmm0[7]
 ; SSE2-NEXT:    psraw $8, %xmm2
-; SSE2-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[2,3,0,1]
-; SSE2-NEXT:    punpcklbw {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3],xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
+; SSE2-NEXT:    punpckhbw {{.*#+}} xmm1 = xmm1[8],xmm0[8],xmm1[9],xmm0[9],xmm1[10],xmm0[10],xmm1[11],xmm0[11],xmm1[12],xmm0[12],xmm1[13],xmm0[13],xmm1[14],xmm0[14],xmm1[15],xmm0[15]
 ; SSE2-NEXT:    psraw $8, %xmm1
 ; SSE2-NEXT:    movdqa %xmm2, %xmm0
 ; SSE2-NEXT:    retq
@@ -55,8 +54,7 @@
 ; SSSE3:       # BB#0: # %entry
 ; SSSE3-NEXT:    punpcklbw {{.*#+}} xmm2 = xmm2[0],xmm0[0],xmm2[1],xmm0[1],xmm2[2],xmm0[2],xmm2[3],xmm0[3],xmm2[4],xmm0[4],xmm2[5],xmm0[5],xmm2[6],xmm0[6],xmm2[7],xmm0[7]
 ; SSSE3-NEXT:    psraw $8, %xmm2
-; SSSE3-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[2,3,0,1]
-; SSSE3-NEXT:    punpcklbw {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3],xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
+; SSSE3-NEXT:    punpckhbw {{.*#+}} xmm1 = xmm1[8],xmm0[8],xmm1[9],xmm0[9],xmm1[10],xmm0[10],xmm1[11],xmm0[11],xmm1[12],xmm0[12],xmm1[13],xmm0[13],xmm1[14],xmm0[14],xmm1[15],xmm0[15]
 ; SSSE3-NEXT:    psraw $8, %xmm1
 ; SSSE3-NEXT:    movdqa %xmm2, %xmm0
 ; SSSE3-NEXT:    retq
@@ -343,8 +341,7 @@
 ; SSE2:       # BB#0: # %entry
 ; SSE2-NEXT:    punpcklwd {{.*#+}} xmm2 = xmm2[0],xmm0[0],xmm2[1],xmm0[1],xmm2[2],xmm0[2],xmm2[3],xmm0[3]
 ; SSE2-NEXT:    psrad $16, %xmm2
-; SSE2-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[2,3,0,1]
-; SSE2-NEXT:    punpcklwd {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3]
+; SSE2-NEXT:    punpckhwd {{.*#+}} xmm1 = xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
 ; SSE2-NEXT:    psrad $16, %xmm1
 ; SSE2-NEXT:    movdqa %xmm2, %xmm0
 ; SSE2-NEXT:    retq
@@ -353,8 +350,7 @@
 ; SSSE3:       # BB#0: # %entry
 ; SSSE3-NEXT:    punpcklwd {{.*#+}} xmm2 = xmm2[0],xmm0[0],xmm2[1],xmm0[1],xmm2[2],xmm0[2],xmm2[3],xmm0[3]
 ; SSSE3-NEXT:    psrad $16, %xmm2
-; SSSE3-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[2,3,0,1]
-; SSSE3-NEXT:    punpcklwd {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3]
+; SSSE3-NEXT:    punpckhwd {{.*#+}} xmm1 = xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
 ; SSSE3-NEXT:    psrad $16, %xmm1
 ; SSSE3-NEXT:    movdqa %xmm2, %xmm0
 ; SSSE3-NEXT:    retq