Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -11472,7 +11472,7 @@
   }
 
   // If it is a splat, check if the argument vector is another splat or a
-  // build_vector with all scalar elements the same.
+  // build_vector.
   if (SVN->isSplat() && SVN->getSplatIndex() < (int)NumElts) {
     SDNode *V = N0.getNode();
 
@@ -11509,6 +11509,17 @@
       // Splat of <x, x, x, x>, return <x, x, x, x>
       if (AllSame)
         return N0;
+
+      // If the splatted element is a constant, just build the vector out of
+      // constants directly.
+      const SDValue& Splatted = V->getOperand(SVN->getSplatIndex());
+      if (isa<ConstantSDNode>(Splatted) || isa<ConstantFPSDNode>(Splatted)) {
+        SmallVector<SDValue, 8> Ops;
+        for (unsigned i = 0; i != NumElts; ++i) {
+          Ops.push_back(Splatted);
+        }
+        return DAG.getNode(ISD::BUILD_VECTOR, SDLoc(N), V->getValueType(0), Ops);
+      }
     }
   }
 
Index: test/CodeGen/X86/splat-const.ll
===================================================================
--- test/CodeGen/X86/splat-const.ll
+++ test/CodeGen/X86/splat-const.ll
@@ -0,0 +1,40 @@
+; RUN: llc < %s -mcpu=penryn | FileCheck %s --check-prefix=SSE
+; RUN: llc < %s -mcpu=sandybridge | FileCheck %s --check-prefix=AVX
+; RUN: llc < %s -mcpu=haswell | FileCheck %s --check-prefix=AVX2
+; This checks that lowering for creation of constant vectors is sane and
+; doesn't use redundant shuffles. (fixes PR22276)
+target triple = "x86_64-unknown-unknown"
+
+define <4 x i32> @zero_vector() {
+; SSE-LABEL: zero_vector:
+; SSE: xorps %xmm0, %xmm0
+; SSE-NEXT: retq
+; AVX-LABEL: zero_vector:
+; AVX: vxorps %xmm0, %xmm0, %xmm0
+; AVX-NEXT: retq
+; AVX2-LABEL: zero_vector:
+; AVX2: vxorps %xmm0, %xmm0, %xmm0
+; AVX2-NEXT: retq
+  %zero = insertelement <4 x i32> undef, i32 0, i32 0
+  %splat = shufflevector <4 x i32> %zero, <4 x i32> undef, <4 x i32> zeroinitializer
+  ret <4 x i32> %splat
+}
+
+; Note that for the "const_vector" versions, lowering that uses a shuffle
+; instead of a load would be legitimate, if it's a single broadcast shuffle.
+; (as opposed to the previous mess)
+; However, this is not the current preferred lowering.
+define <4 x i32> @const_vector() {
+; SSE-LABEL: const_vector:
+; SSE: movaps {{.*}}, %xmm0 # xmm0 = [42,42,42,42]
+; SSE-NEXT: retq
+; AVX-LABEL: const_vector:
+; AVX: vmovaps {{.*}}, %xmm0 # xmm0 = [42,42,42,42]
+; AVX-NEXT: retq
+; AVX2-LABEL: const_vector:
+; AVX2: vbroadcastss {{[^%].*}}, %xmm0
+; AVX2-NEXT: retq
+  %zero = insertelement <4 x i32> undef, i32 42, i32 0
+  %splat = shufflevector <4 x i32> %zero, <4 x i32> undef, <4 x i32> zeroinitializer
+  ret <4 x i32> %splat
+}
Index: test/CodeGen/X86/sse41.ll
===================================================================
--- test/CodeGen/X86/sse41.ll
+++ test/CodeGen/X86/sse41.ll
@@ -1005,14 +1005,14 @@
 ; X32-LABEL: insertps_pr20411:
 ; X32:       ## BB#0:
 ; X32-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; X32-NEXT:    pshufd {{.*#+}} xmm0 = mem[3,1,2,3]
+; X32-NEXT:    movaps {{.*#+}} xmm0 = [3,3,3,3]
 ; X32-NEXT:    insertps $-36, LCPI49_1+12, %xmm0
 ; X32-NEXT:    movups %xmm0, (%eax)
 ; X32-NEXT:    retl
 ;
 ; X64-LABEL: insertps_pr20411:
 ; X64:       ## BB#0:
-; X64-NEXT:    pshufd {{.*#+}} xmm0 = mem[3,1,2,3]
+; X64-NEXT:    movaps {{.*#+}} xmm0 = [3,3,3,3]
 ; X64-NEXT:    insertps $-36, LCPI49_1+{{.*}}(%rip), %xmm0
 ; X64-NEXT:    movups %xmm0, (%rdi)
 ; X64-NEXT:    retq
Index: test/CodeGen/X86/widen_shuffle-1.ll
===================================================================
--- test/CodeGen/X86/widen_shuffle-1.ll
+++ test/CodeGen/X86/widen_shuffle-1.ll
@@ -82,8 +82,8 @@
 ; CHECK-LABEL: shuf5:
 ; CHECK:       # BB#0:
 ; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; CHECK-NEXT:    movdqa {{.*#+}} xmm0 = <4,33,u,u,u,u,u,u>
-; CHECK-NEXT:    pshufb {{.*#+}} xmm0 = xmm0[2,2,4,6,8,10,12,14,u,u,u,u,u,u,u,u]
+; CHECK-NEXT:    movdqa {{.*#+}} xmm0 = [33,33,33,33,33,33,33,33]
+; CHECK-NEXT:    pshufb {{.*#+}} xmm0 = xmm0[0,2,4,6,8,10,12,14,u,u,u,u,u,u,u,u]
 ; CHECK-NEXT:    movlpd %xmm0, (%eax)
 ; CHECK-NEXT:    retl
   %v = shufflevector <2 x i8> <i8 4, i8 33>, <2 x i8> undef, <8 x i32> <i32 1, i32 1, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef>