diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -5733,11 +5733,11 @@
 
   // Convert vector index to bit-index and get the required bit mask.
   assert(isPowerOf2_32(EltSize));
+  const auto EltMask = maskTrailingOnes<uint64_t>(EltSize);
   SDValue ScaleFactor = DAG.getConstant(Log2_32(EltSize), SL, MVT::i32);
   SDValue ScaledIdx = DAG.getNode(ISD::SHL, SL, MVT::i32, Idx, ScaleFactor);
   SDValue BFM = DAG.getNode(ISD::SHL, SL, IntVT,
-                            DAG.getConstant(0xffff, SL, IntVT),
-                            ScaledIdx);
+                            DAG.getConstant(EltMask, SL, IntVT), ScaledIdx);
 
   // 1. Create a congruent vector with the target value in each element.
   SDValue ExtVal = DAG.getNode(ISD::BITCAST, SL, IntVT,
diff --git a/llvm/test/CodeGen/AMDGPU/insert_vector_dynelt.ll b/llvm/test/CodeGen/AMDGPU/insert_vector_dynelt.ll
--- a/llvm/test/CodeGen/AMDGPU/insert_vector_dynelt.ll
+++ b/llvm/test/CodeGen/AMDGPU/insert_vector_dynelt.ll
@@ -447,7 +447,7 @@
 ; GCN:       ; %bb.0: ; %entry
 ; GCN-NEXT:    s_load_dword s6, s[0:1], 0x34
 ; GCN-NEXT:    s_load_dwordx4 s[0:3], s[0:1], 0x24
-; GCN-NEXT:    s_mov_b64 s[4:5], 0xffff
+; GCN-NEXT:    s_mov_b64 s[4:5], 0xff
 ; GCN-NEXT:    s_waitcnt lgkmcnt(0)
 ; GCN-NEXT:    s_lshl_b32 s6, s6, 3
 ; GCN-NEXT:    s_lshl_b64 s[4:5], s[4:5], s6
diff --git a/llvm/test/CodeGen/AMDGPU/insert_vector_elt.ll b/llvm/test/CodeGen/AMDGPU/insert_vector_elt.ll
--- a/llvm/test/CodeGen/AMDGPU/insert_vector_elt.ll
+++ b/llvm/test/CodeGen/AMDGPU/insert_vector_elt.ll
@@ -1033,7 +1033,7 @@
 ; SI-NEXT:    s_mov_b32 s2, -1
 ; SI-NEXT:    s_waitcnt lgkmcnt(0)
 ; SI-NEXT:    s_lshl_b32 s5, s6, 3
-; SI-NEXT:    s_lshl_b32 s5, -1, s5
+; SI-NEXT:    s_lshl_b32 s5, 0xff, s5
 ; SI-NEXT:    s_andn2_b32 s4, s4, s5
 ; SI-NEXT:    s_and_b32 s5, s5, 0x505
 ; SI-NEXT:    s_or_b32 s4, s5, s4
@@ -1046,14 +1046,15 @@
 ; VI-NEXT:    s_load_dword s6, s[4:5], 0x4c
 ; VI-NEXT:    s_load_dwordx2 s[0:1], s[4:5], 0x0
 ; VI-NEXT:    s_load_dword s4, s[4:5], 0x28
+; VI-NEXT:    v_mov_b32_e32 v0, 0xff
 ; VI-NEXT:    s_mov_b32 s3, 0x1100f000
-; VI-NEXT:    s_mov_b32 s2, -1
 ; VI-NEXT:    s_waitcnt lgkmcnt(0)
 ; VI-NEXT:    s_lshl_b32 s5, s6, 3
-; VI-NEXT:    v_lshlrev_b16_e64 v0, s5, -1
+; VI-NEXT:    v_lshlrev_b16_e32 v0, s5, v0
 ; VI-NEXT:    v_not_b32_e32 v1, v0
 ; VI-NEXT:    v_and_b32_e32 v1, s4, v1
 ; VI-NEXT:    v_and_b32_e32 v0, 0x505, v0
+; VI-NEXT:    s_mov_b32 s2, -1
 ; VI-NEXT:    v_or_b32_e32 v0, v0, v1
 ; VI-NEXT:    buffer_store_short v0, off, s[0:3], 0
 ; VI-NEXT:    s_endpgm
@@ -1074,7 +1075,7 @@
 ; SI-NEXT:    s_mov_b32 s2, -1
 ; SI-NEXT:    s_waitcnt lgkmcnt(0)
 ; SI-NEXT:    s_lshl_b32 s5, s6, 3
-; SI-NEXT:    s_lshl_b32 s5, 0xffff, s5
+; SI-NEXT:    s_lshl_b32 s5, 0xff, s5
 ; SI-NEXT:    s_andn2_b32 s4, s4, s5
 ; SI-NEXT:    s_and_b32 s5, s5, 0x5050505
 ; SI-NEXT:    s_or_b32 s4, s5, s4
@@ -1094,7 +1095,7 @@
 ; VI-NEXT:    s_mov_b32 s2, -1
 ; VI-NEXT:    s_waitcnt lgkmcnt(0)
 ; VI-NEXT:    s_lshl_b32 s5, s6, 3
-; VI-NEXT:    s_lshl_b32 s5, 0xffff, s5
+; VI-NEXT:    s_lshl_b32 s5, 0xff, s5
 ; VI-NEXT:    s_andn2_b32 s4, s4, s5
 ; VI-NEXT:    s_and_b32 s5, s5, 0x5050505
 ; VI-NEXT:    s_or_b32 s4, s5, s4
@@ -1119,7 +1120,7 @@
 ; SI-NEXT:    s_mov_b32 s2, -1
 ; SI-NEXT:    s_waitcnt lgkmcnt(0)
 ; SI-NEXT:    s_lshl_b32 s5, s6, 3
-; SI-NEXT:    s_lshl_b32 s5, 0xffff, s5
+; SI-NEXT:    s_lshl_b32 s5, 0xff, s5
 ; SI-NEXT:    s_andn2_b32 s4, s4, s5
 ; SI-NEXT:    s_and_b32 s5, s5, 0x5050505
 ; SI-NEXT:    s_or_b32 s4, s5, s4
@@ -1136,7 +1137,7 @@
 ; VI-NEXT:    s_mov_b32 s2, -1
 ; VI-NEXT:    s_waitcnt lgkmcnt(0)
 ; VI-NEXT:    s_lshl_b32 s5, s6, 3
-; VI-NEXT:    s_lshl_b32 s5, 0xffff, s5
+; VI-NEXT:    s_lshl_b32 s5, 0xff, s5
 ; VI-NEXT:    s_andn2_b32 s4, s4, s5
 ; VI-NEXT:    s_and_b32 s5, s5, 0x5050505
 ; VI-NEXT:    s_or_b32 s4, s5, s4
@@ -1160,7 +1161,7 @@
 ; SI-NEXT:    s_mov_b32 s5, s1
 ; SI-NEXT:    s_load_dwordx2 s[0:1], s[2:3], 0x0
 ; SI-NEXT:    s_lshl_b32 s8, s8, 3
-; SI-NEXT:    s_mov_b64 s[2:3], 0xffff
+; SI-NEXT:    s_mov_b64 s[2:3], 0xff
 ; SI-NEXT:    s_lshl_b64 s[2:3], s[2:3], s8
 ; SI-NEXT:    s_and_b32 s9, s3, 0x5050505
 ; SI-NEXT:    s_and_b32 s8, s2, 0x5050505
@@ -1183,7 +1184,7 @@
 ; VI-NEXT:    s_mov_b32 s5, s1
 ; VI-NEXT:    s_load_dwordx2 s[0:1], s[2:3], 0x0
 ; VI-NEXT:    s_lshl_b32 s8, s8, 3
-; VI-NEXT:    s_mov_b64 s[2:3], 0xffff
+; VI-NEXT:    s_mov_b64 s[2:3], 0xff
 ; VI-NEXT:    s_lshl_b64 s[2:3], s[2:3], s8
 ; VI-NEXT:    s_and_b32 s9, s3, 0x5050505
 ; VI-NEXT:    s_and_b32 s8, s2, 0x5050505