Index: include/llvm/CodeGen/GlobalISel/LegalizerHelper.h
===================================================================
--- include/llvm/CodeGen/GlobalISel/LegalizerHelper.h
+++ include/llvm/CodeGen/GlobalISel/LegalizerHelper.h
@@ -203,6 +203,10 @@
   LegalizeResult fewerElementsVectorUnmergeValues(MachineInstr &MI,
                                                   unsigned TypeIdx,
                                                   LLT NarrowTy);
+  LegalizeResult fewerElementsVectorBuildVector(MachineInstr &MI,
+                                                unsigned TypeIdx,
+                                                LLT NarrowTy);
+
   LegalizeResult
   reduceLoadStoreWidth(MachineInstr &MI, unsigned TypeIdx, LLT NarrowTy);
 
Index: lib/CodeGen/GlobalISel/LegalizerHelper.cpp
===================================================================
--- lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -2785,6 +2785,65 @@
   return Legalized;
 }
 
+LegalizerHelper::LegalizeResult
+LegalizerHelper::fewerElementsVectorBuildVector(MachineInstr &MI,
+                                                unsigned TypeIdx,
+                                                LLT NarrowTy) {
+  assert(TypeIdx == 0 && "not a vector type index");
+  Register DstReg = MI.getOperand(0).getReg();
+  LLT DstTy = MRI.getType(DstReg);
+  LLT SrcTy = DstTy.getElementType();
+
+  int DstNumElts = DstTy.getNumElements();
+  int NarrowNumElts = NarrowTy.getNumElements();
+  int NumConcat = (DstNumElts + NarrowNumElts - 1) / NarrowNumElts;
+  LLT WidenedDstTy = LLT::vector(NarrowNumElts * NumConcat, SrcTy);
+
+  SmallVector<Register, 8> ConcatOps;
+  SmallVector<Register, 8> SubBuildVector;
+
+  Register UndefReg;
+  if (WidenedDstTy != DstTy)
+    UndefReg = MIRBuilder.buildUndef(SrcTy).getReg(0);
+
+  // Create a G_CONCAT_VECTORS of NarrowTy pieces, padding with undef as
+  // necessary.
+  //
+  // %3:_(<3 x s16>) = G_BUILD_VECTOR %0, %1, %2
+  //   -> <2 x s16>
+  //
+  // %4:_(s16) = G_IMPLICIT_DEF
+  // %5:_(<2 x s16>) = G_BUILD_VECTOR %0, %1
+  // %6:_(<2 x s16>) = G_BUILD_VECTOR %2, %4
+  // %7:_(<4 x s16>) = G_CONCAT_VECTORS %5, %6
+  // %3:_(<3 x s16>) = G_EXTRACT %7, 0
+  for (int I = 0; I != NumConcat; ++I) {
+    for (int J = 0; J != NarrowNumElts; ++J) {
+      int SrcIdx = NarrowNumElts * I + J;
+
+      if (SrcIdx < DstNumElts) {
+        Register SrcReg = MI.getOperand(SrcIdx + 1).getReg();
+        SubBuildVector.push_back(SrcReg);
+      } else
+        SubBuildVector.push_back(UndefReg);
+    }
+
+    auto BuildVec = MIRBuilder.buildBuildVector(NarrowTy, SubBuildVector);
+    ConcatOps.push_back(BuildVec.getReg(0));
+    SubBuildVector.clear();
+  }
+
+  if (DstTy == WidenedDstTy)
+    MIRBuilder.buildConcatVectors(DstReg, ConcatOps);
+  else {
+    auto Concat = MIRBuilder.buildConcatVectors(WidenedDstTy, ConcatOps);
+    MIRBuilder.buildExtract(DstReg, Concat, 0);
+  }
+
+  MI.eraseFromParent();
+  return Legalized;
+}
+
 LegalizerHelper::LegalizeResult
 LegalizerHelper::reduceLoadStoreWidth(MachineInstr &MI, unsigned TypeIdx,
                                       LLT NarrowTy) {
@@ -2960,6 +3019,8 @@
     return fewerElementsVectorPhi(MI, TypeIdx, NarrowTy);
   case G_UNMERGE_VALUES:
     return fewerElementsVectorUnmergeValues(MI, TypeIdx, NarrowTy);
+  case G_BUILD_VECTOR:
+    return fewerElementsVectorBuildVector(MI, TypeIdx, NarrowTy);
   case G_LOAD:
   case G_STORE:
     return reduceLoadStoreWidth(MI, TypeIdx, NarrowTy);
Index: lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
===================================================================
--- lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
+++ lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
@@ -58,6 +58,14 @@
   };
 }
 
+static LegalityPredicate isWideVec16(unsigned TypeIdx) {
+  return [=](const LegalityQuery &Query) {
+    const LLT Ty = Query.Types[TypeIdx];
+    const LLT EltTy = Ty.getScalarType();
+    return EltTy.getSizeInBits() == 16 && Ty.getNumElements() > 2;
+  };
+}
+
 static LegalizeMutation oneMoreElement(unsigned TypeIdx) {
   return [=](const LegalityQuery &Query) {
     const LLT Ty = Query.Types[TypeIdx];
@@ -931,7 +939,8 @@
     .legalForCartesianProduct(AllS32Vectors, {S32})
     .legalForCartesianProduct(AllS64Vectors, {S64})
     .clampNumElements(0, V16S32, V32S32)
-    .clampNumElements(0, V2S64, V16S64);
+    .clampNumElements(0, V2S64, V16S64)
+    .fewerElementsIf(isWideVec16(0), changeTo(0, V2S16));
 
   if (ST.hasScalarPackInsts())
     BuildVector.legalFor({V2S16, S32});
Index: test/CodeGen/AMDGPU/GlobalISel/legalize-build-vector.mir
===================================================================
--- test/CodeGen/AMDGPU/GlobalISel/legalize-build-vector.mir
+++ test/CodeGen/AMDGPU/GlobalISel/legalize-build-vector.mir
@@ -822,3 +822,303 @@
     %4:_(<4 x s128>) = G_BUILD_VECTOR %0, %1, %2, %3
     S_NOP 0, implicit %4
 ...
+
+---
+name: build_vector_v2s16
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1
+
+    ; CHECK-LABEL: name: build_vector_v2s16
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[COPY]](s32)
+    ; CHECK: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[COPY1]](s32)
+    ; CHECK: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; CHECK: S_NOP 0, implicit [[BUILD_VECTOR]](<2 x s16>)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s16) = G_TRUNC %0
+    %3:_(s16) = G_TRUNC %1
+    %4:_(<2 x s16>) = G_BUILD_VECTOR %2, %3
+    S_NOP 0, implicit %4
+...
+
+---
+name: build_vector_v3s16
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1, $vgpr2
+
+    ; CHECK-LABEL: name: build_vector_v3s16
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY $vgpr2
+    ; CHECK: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[COPY]](s32)
+    ; CHECK: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[COPY1]](s32)
+    ; CHECK: [[TRUNC2:%[0-9]+]]:_(s16) = G_TRUNC [[COPY2]](s32)
+    ; CHECK: [[DEF:%[0-9]+]]:_(s16) = G_IMPLICIT_DEF
+    ; CHECK: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; CHECK: [[BUILD_VECTOR1:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC2]](s16), [[DEF]](s16)
+    ; CHECK: [[CONCAT_VECTORS:%[0-9]+]]:_(<4 x s16>) = G_CONCAT_VECTORS [[BUILD_VECTOR]](<2 x s16>), [[BUILD_VECTOR1]](<2 x s16>)
+    ; CHECK: [[EXTRACT:%[0-9]+]]:_(<3 x s16>) = G_EXTRACT [[CONCAT_VECTORS]](<4 x s16>), 0
+    ; CHECK: S_NOP 0, implicit [[EXTRACT]](<3 x s16>)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s32) = COPY $vgpr2
+    %3:_(s16) = G_TRUNC %0
+    %4:_(s16) = G_TRUNC %1
+    %5:_(s16) = G_TRUNC %2
+    %6:_(<3 x s16>) = G_BUILD_VECTOR %3, %4, %5
+    S_NOP 0, implicit %6
+...
+
+---
+name: build_vector_v4s16
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1, $vgpr2, $vgpr3
+
+    ; CHECK-LABEL: name: build_vector_v4s16
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY $vgpr2
+    ; CHECK: [[COPY3:%[0-9]+]]:_(s32) = COPY $vgpr3
+    ; CHECK: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[COPY]](s32)
+    ; CHECK: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[COPY1]](s32)
+    ; CHECK: [[TRUNC2:%[0-9]+]]:_(s16) = G_TRUNC [[COPY2]](s32)
+    ; CHECK: [[TRUNC3:%[0-9]+]]:_(s16) = G_TRUNC [[COPY3]](s32)
+    ; CHECK: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; CHECK: [[BUILD_VECTOR1:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC2]](s16), [[TRUNC3]](s16)
+    ; CHECK: [[CONCAT_VECTORS:%[0-9]+]]:_(<4 x s16>) = G_CONCAT_VECTORS [[BUILD_VECTOR]](<2 x s16>), [[BUILD_VECTOR1]](<2 x s16>)
+    ; CHECK: S_NOP 0, implicit [[CONCAT_VECTORS]](<4 x s16>)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s32) = COPY $vgpr2
+    %3:_(s32) = COPY $vgpr3
+    %4:_(s16) = G_TRUNC %0
+    %5:_(s16) = G_TRUNC %1
+    %6:_(s16) = G_TRUNC %2
+    %7:_(s16) = G_TRUNC %3
+    %8:_(<4 x s16>) = G_BUILD_VECTOR %4, %5, %6, %7
+    S_NOP 0, implicit %8
+...
+
+---
+name: build_vector_v5s16
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1, $vgpr2, $vgpr3, $vgpr4
+
+    ; CHECK-LABEL: name: build_vector_v5s16
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY $vgpr2
+    ; CHECK: [[COPY3:%[0-9]+]]:_(s32) = COPY $vgpr3
+    ; CHECK: [[COPY4:%[0-9]+]]:_(s32) = COPY $vgpr4
+    ; CHECK: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[COPY]](s32)
+    ; CHECK: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[COPY1]](s32)
+    ; CHECK: [[TRUNC2:%[0-9]+]]:_(s16) = G_TRUNC [[COPY2]](s32)
+    ; CHECK: [[TRUNC3:%[0-9]+]]:_(s16) = G_TRUNC [[COPY3]](s32)
+    ; CHECK: [[TRUNC4:%[0-9]+]]:_(s16) = G_TRUNC [[COPY4]](s32)
+    ; CHECK: [[DEF:%[0-9]+]]:_(s16) = G_IMPLICIT_DEF
+    ; CHECK: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; CHECK: [[BUILD_VECTOR1:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC2]](s16), [[TRUNC3]](s16)
+    ; CHECK: [[BUILD_VECTOR2:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC4]](s16), [[DEF]](s16)
+    ; CHECK: [[CONCAT_VECTORS:%[0-9]+]]:_(<6 x s16>) = G_CONCAT_VECTORS [[BUILD_VECTOR]](<2 x s16>), [[BUILD_VECTOR1]](<2 x s16>), [[BUILD_VECTOR2]](<2 x s16>)
+    ; CHECK: [[EXTRACT:%[0-9]+]]:_(<5 x s16>) = G_EXTRACT [[CONCAT_VECTORS]](<6 x s16>), 0
+    ; CHECK: S_NOP 0, implicit [[EXTRACT]](<5 x s16>)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s32) = COPY $vgpr2
+    %3:_(s32) = COPY $vgpr3
+    %4:_(s32) = COPY $vgpr4
+    %5:_(s16) = G_TRUNC %0
+    %6:_(s16) = G_TRUNC %1
+    %7:_(s16) = G_TRUNC %2
+    %8:_(s16) = G_TRUNC %3
+    %9:_(s16) = G_TRUNC %4
+    %10:_(<5 x s16>) = G_BUILD_VECTOR %5, %6, %7, %8, %9
+    S_NOP 0, implicit %10
+...
+
+---
+name: build_vector_v7s16
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1, $vgpr2, $vgpr3, $vgpr4, $vgpr5, $vgpr6
+
+    ; CHECK-LABEL: name: build_vector_v7s16
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY $vgpr2
+    ; CHECK: [[COPY3:%[0-9]+]]:_(s32) = COPY $vgpr3
+    ; CHECK: [[COPY4:%[0-9]+]]:_(s32) = COPY $vgpr4
+    ; CHECK: [[COPY5:%[0-9]+]]:_(s32) = COPY $vgpr5
+    ; CHECK: [[COPY6:%[0-9]+]]:_(s32) = COPY $vgpr6
+    ; CHECK: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[COPY]](s32)
+    ; CHECK: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[COPY1]](s32)
+    ; CHECK: [[TRUNC2:%[0-9]+]]:_(s16) = G_TRUNC [[COPY2]](s32)
+    ; CHECK: [[TRUNC3:%[0-9]+]]:_(s16) = G_TRUNC [[COPY3]](s32)
+    ; CHECK: [[TRUNC4:%[0-9]+]]:_(s16) = G_TRUNC [[COPY4]](s32)
+    ; CHECK: [[TRUNC5:%[0-9]+]]:_(s16) = G_TRUNC [[COPY5]](s32)
+    ; CHECK: [[TRUNC6:%[0-9]+]]:_(s16) = G_TRUNC [[COPY6]](s32)
+    ; CHECK: [[DEF:%[0-9]+]]:_(s16) = G_IMPLICIT_DEF
+    ; CHECK: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; CHECK: [[BUILD_VECTOR1:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC2]](s16), [[TRUNC3]](s16)
+    ; CHECK: [[BUILD_VECTOR2:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC4]](s16), [[TRUNC5]](s16)
+    ; CHECK: [[BUILD_VECTOR3:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC6]](s16), [[DEF]](s16)
+    ; CHECK: [[CONCAT_VECTORS:%[0-9]+]]:_(<8 x s16>) = G_CONCAT_VECTORS [[BUILD_VECTOR]](<2 x s16>), [[BUILD_VECTOR1]](<2 x s16>), [[BUILD_VECTOR2]](<2 x s16>), [[BUILD_VECTOR3]](<2 x s16>)
+    ; CHECK: [[EXTRACT:%[0-9]+]]:_(<7 x s16>) = G_EXTRACT [[CONCAT_VECTORS]](<8 x s16>), 0
+    ; CHECK: S_NOP 0, implicit [[EXTRACT]](<7 x s16>)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s32) = COPY $vgpr2
+    %3:_(s32) = COPY $vgpr3
+    %4:_(s32) = COPY $vgpr4
+    %5:_(s32) = COPY $vgpr5
+    %6:_(s32) = COPY $vgpr6
+    %7:_(s16) = G_TRUNC %0
+    %8:_(s16) = G_TRUNC %1
+    %9:_(s16) = G_TRUNC %2
+    %10:_(s16) = G_TRUNC %3
+    %11:_(s16) = G_TRUNC %4
+    %12:_(s16) = G_TRUNC %5
+    %13:_(s16) = G_TRUNC %6
+    %14:_(<7 x s16>) = G_BUILD_VECTOR %7, %8, %9, %10, %11, %12, %13
+    S_NOP 0, implicit %14
+...
+
+---
+name: build_vector_v8s16
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1, $vgpr2, $vgpr3, $vgpr4, $vgpr5, $vgpr6, $vgpr7
+
+    ; CHECK-LABEL: name: build_vector_v8s16
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY $vgpr2
+    ; CHECK: [[COPY3:%[0-9]+]]:_(s32) = COPY $vgpr3
+    ; CHECK: [[COPY4:%[0-9]+]]:_(s32) = COPY $vgpr4
+    ; CHECK: [[COPY5:%[0-9]+]]:_(s32) = COPY $vgpr5
+    ; CHECK: [[COPY6:%[0-9]+]]:_(s32) = COPY $vgpr6
+    ; CHECK: [[COPY7:%[0-9]+]]:_(s32) = COPY $vgpr7
+    ; CHECK: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[COPY]](s32)
+    ; CHECK: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[COPY1]](s32)
+    ; CHECK: [[TRUNC2:%[0-9]+]]:_(s16) = G_TRUNC [[COPY2]](s32)
+    ; CHECK: [[TRUNC3:%[0-9]+]]:_(s16) = G_TRUNC [[COPY3]](s32)
+    ; CHECK: [[TRUNC4:%[0-9]+]]:_(s16) = G_TRUNC [[COPY4]](s32)
+    ; CHECK: [[TRUNC5:%[0-9]+]]:_(s16) = G_TRUNC [[COPY5]](s32)
+    ; CHECK: [[TRUNC6:%[0-9]+]]:_(s16) = G_TRUNC [[COPY6]](s32)
+    ; CHECK: [[TRUNC7:%[0-9]+]]:_(s16) = G_TRUNC [[COPY7]](s32)
+    ; CHECK: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; CHECK: [[BUILD_VECTOR1:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC2]](s16), [[TRUNC3]](s16)
+    ; CHECK: [[BUILD_VECTOR2:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC4]](s16), [[TRUNC5]](s16)
+    ; CHECK: [[BUILD_VECTOR3:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC6]](s16), [[TRUNC7]](s16)
+    ; CHECK: [[CONCAT_VECTORS:%[0-9]+]]:_(<8 x s16>) = G_CONCAT_VECTORS [[BUILD_VECTOR]](<2 x s16>), [[BUILD_VECTOR1]](<2 x s16>), [[BUILD_VECTOR2]](<2 x s16>), [[BUILD_VECTOR3]](<2 x s16>)
+    ; CHECK: S_NOP 0, implicit [[CONCAT_VECTORS]](<8 x s16>)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s32) = COPY $vgpr2
+    %3:_(s32) = COPY $vgpr3
+    %4:_(s32) = COPY $vgpr4
+    %5:_(s32) = COPY $vgpr5
+    %6:_(s32) = COPY $vgpr6
+    %7:_(s32) = COPY $vgpr7
+    %8:_(s16) = G_TRUNC %0
+    %9:_(s16) = G_TRUNC %1
+    %10:_(s16) = G_TRUNC %2
+    %11:_(s16) = G_TRUNC %3
+    %12:_(s16) = G_TRUNC %4
+    %13:_(s16) = G_TRUNC %5
+    %14:_(s16) = G_TRUNC %6
+    %15:_(s16) = G_TRUNC %7
+    %16:_(<8 x s16>) = G_BUILD_VECTOR %8, %9, %10, %11, %12, %13, %14, %15
+    S_NOP 0, implicit %16
+...
+
+---
+name: build_vector_v16s16
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1, $vgpr2, $vgpr3, $vgpr4, $vgpr5, $vgpr6, $vgpr7, $vgpr8, $vgpr9, $vgpr10, $vgpr11, $vgpr12, $vgpr13, $vgpr14, $vgpr15
+
+    ; CHECK-LABEL: name: build_vector_v16s16
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY $vgpr2
+    ; CHECK: [[COPY3:%[0-9]+]]:_(s32) = COPY $vgpr3
+    ; CHECK: [[COPY4:%[0-9]+]]:_(s32) = COPY $vgpr4
+    ; CHECK: [[COPY5:%[0-9]+]]:_(s32) = COPY $vgpr5
+    ; CHECK: [[COPY6:%[0-9]+]]:_(s32) = COPY $vgpr6
+    ; CHECK: [[COPY7:%[0-9]+]]:_(s32) = COPY $vgpr7
+    ; CHECK: [[COPY8:%[0-9]+]]:_(s32) = COPY $vgpr8
+    ; CHECK: [[COPY9:%[0-9]+]]:_(s32) = COPY $vgpr9
+    ; CHECK: [[COPY10:%[0-9]+]]:_(s32) = COPY $vgpr10
+    ; CHECK: [[COPY11:%[0-9]+]]:_(s32) = COPY $vgpr11
+    ; CHECK: [[COPY12:%[0-9]+]]:_(s32) = COPY $vgpr12
+    ; CHECK: [[COPY13:%[0-9]+]]:_(s32) = COPY $vgpr13
+    ; CHECK: [[COPY14:%[0-9]+]]:_(s32) = COPY $vgpr14
+    ; CHECK: [[COPY15:%[0-9]+]]:_(s32) = COPY $vgpr15
+    ; CHECK: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[COPY]](s32)
+    ; CHECK: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[COPY1]](s32)
+    ; CHECK: [[TRUNC2:%[0-9]+]]:_(s16) = G_TRUNC [[COPY2]](s32)
+    ; CHECK: [[TRUNC3:%[0-9]+]]:_(s16) = G_TRUNC [[COPY3]](s32)
+    ; CHECK: [[TRUNC4:%[0-9]+]]:_(s16) = G_TRUNC [[COPY4]](s32)
+    ; CHECK: [[TRUNC5:%[0-9]+]]:_(s16) = G_TRUNC [[COPY5]](s32)
+    ; CHECK: [[TRUNC6:%[0-9]+]]:_(s16) = G_TRUNC [[COPY6]](s32)
+    ; CHECK: [[TRUNC7:%[0-9]+]]:_(s16) = G_TRUNC [[COPY7]](s32)
+    ; CHECK: [[TRUNC8:%[0-9]+]]:_(s16) = G_TRUNC [[COPY8]](s32)
+    ; CHECK: [[TRUNC9:%[0-9]+]]:_(s16) = G_TRUNC [[COPY9]](s32)
+    ; CHECK: [[TRUNC10:%[0-9]+]]:_(s16) = G_TRUNC [[COPY10]](s32)
+    ; CHECK: [[TRUNC11:%[0-9]+]]:_(s16) = G_TRUNC [[COPY11]](s32)
+    ; CHECK: [[TRUNC12:%[0-9]+]]:_(s16) = G_TRUNC [[COPY12]](s32)
+    ; CHECK: [[TRUNC13:%[0-9]+]]:_(s16) = G_TRUNC [[COPY13]](s32)
+    ; CHECK: [[TRUNC14:%[0-9]+]]:_(s16) = G_TRUNC [[COPY14]](s32)
+    ; CHECK: [[TRUNC15:%[0-9]+]]:_(s16) = G_TRUNC [[COPY15]](s32)
+    ; CHECK: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; CHECK: [[BUILD_VECTOR1:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC2]](s16), [[TRUNC3]](s16)
+    ; CHECK: [[BUILD_VECTOR2:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC4]](s16), [[TRUNC5]](s16)
+    ; CHECK: [[BUILD_VECTOR3:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC6]](s16), [[TRUNC7]](s16)
+    ; CHECK: [[BUILD_VECTOR4:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC8]](s16), [[TRUNC9]](s16)
+    ; CHECK: [[BUILD_VECTOR5:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC10]](s16), [[TRUNC11]](s16)
+    ; CHECK: [[BUILD_VECTOR6:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC12]](s16), [[TRUNC13]](s16)
+    ; CHECK: [[BUILD_VECTOR7:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC14]](s16), [[TRUNC15]](s16)
+    ; CHECK: [[CONCAT_VECTORS:%[0-9]+]]:_(<16 x s16>) = G_CONCAT_VECTORS [[BUILD_VECTOR]](<2 x s16>), [[BUILD_VECTOR1]](<2 x s16>), [[BUILD_VECTOR2]](<2 x s16>), [[BUILD_VECTOR3]](<2 x s16>), [[BUILD_VECTOR4]](<2 x s16>), [[BUILD_VECTOR5]](<2 x s16>), [[BUILD_VECTOR6]](<2 x s16>), [[BUILD_VECTOR7]](<2 x s16>)
+    ; CHECK: S_NOP 0, implicit [[CONCAT_VECTORS]](<16 x s16>)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s32) = COPY $vgpr2
+    %3:_(s32) = COPY $vgpr3
+    %4:_(s32) = COPY $vgpr4
+    %5:_(s32) = COPY $vgpr5
+    %6:_(s32) = COPY $vgpr6
+    %7:_(s32) = COPY $vgpr7
+    %8:_(s32) = COPY $vgpr8
+    %9:_(s32) = COPY $vgpr9
+    %10:_(s32) = COPY $vgpr10
+    %11:_(s32) = COPY $vgpr11
+    %12:_(s32) = COPY $vgpr12
+    %13:_(s32) = COPY $vgpr13
+    %14:_(s32) = COPY $vgpr14
+    %15:_(s32) = COPY $vgpr15
+    %16:_(s16) = G_TRUNC %0
+    %17:_(s16) = G_TRUNC %1
+    %18:_(s16) = G_TRUNC %2
+    %19:_(s16) = G_TRUNC %3
+    %20:_(s16) = G_TRUNC %4
+    %21:_(s16) = G_TRUNC %5
+    %22:_(s16) = G_TRUNC %6
+    %23:_(s16) = G_TRUNC %7
+    %24:_(s16) = G_TRUNC %8
+    %25:_(s16) = G_TRUNC %9
+    %26:_(s16) = G_TRUNC %10
+    %27:_(s16) = G_TRUNC %11
+    %28:_(s16) = G_TRUNC %12
+    %29:_(s16) = G_TRUNC %13
+    %30:_(s16) = G_TRUNC %14
+    %31:_(s16) = G_TRUNC %15
+    %32:_(<16 x s16>) = G_BUILD_VECTOR  %16, %17, %18, %19, %20, %21, %22, %23, %24, %25, %26, %27, %28, %29, %30, %31
+    S_NOP 0, implicit %32
+...