diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.h b/llvm/lib/Target/AMDGPU/SIISelLowering.h
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.h
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.h
@@ -231,10 +231,8 @@
   // Analyze a combined offset from an amdgcn_buffer_ intrinsic and store the
   // three offsets (voffset, soffset and instoffset) into the SDValue[3] array
   // pointed to by Offsets.
-  /// \returns 0 If there is a non-constant offset or if the offset is 0.
-  /// Otherwise returns the constant offset.
-  unsigned setBufferOffsets(SDValue CombinedOffset, SelectionDAG &DAG,
-                            SDValue *Offsets, Align Alignment = Align(4)) const;
+  void setBufferOffsets(SDValue CombinedOffset, SelectionDAG &DAG,
+                        SDValue *Offsets, Align Alignment = Align(4)) const;
 
   // Handle 8 bit and 16 bit buffer loads
   SDValue handleByteShortBufferLoads(SelectionDAG &DAG, EVT LoadVT, SDLoc DL,
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
@@ -6795,28 +6795,24 @@
   }
 }
 
-// This function computes an appropriate offset to pass to
-// MachineMemOperand::setOffset() based on the offset inputs to
-// an intrinsic.  If any of the offsets are non-contstant or
-// if VIndex is non-zero then this function returns 0.  Otherwise,
-// it returns the sum of VOffset, SOffset, and Offset.
-static unsigned getBufferOffsetForMMO(SDValue VOffset,
-                                      SDValue SOffset,
-                                      SDValue Offset,
-                                      SDValue VIndex = SDValue()) {
-
+/// Update \p MMO based on the offset inputs to an intrinsic.  If any of the
+/// offsets are non-constant or if \p VIndex is non-zero then this function does
+/// nothing.  Otherwise, it sets the MMO offset to the sum of \p VOffset, \p
+/// SOffset, and \p Offset.
+static void updateBufferMMO(MachineMemOperand *MMO, SDValue VOffset,
+                            SDValue SOffset, SDValue Offset,
+                            SDValue VIndex = SDValue()) {
   if (!isa<ConstantSDNode>(VOffset) || !isa<ConstantSDNode>(SOffset) ||
       !isa<ConstantSDNode>(Offset))
-    return 0;
+    return;
 
-  if (VIndex) {
-    if (!isa<ConstantSDNode>(VIndex) || !cast<ConstantSDNode>(VIndex)->isNullValue())
-      return 0;
-  }
+  if (VIndex && (!isa<ConstantSDNode>(VIndex) ||
+                 !cast<ConstantSDNode>(VIndex)->isNullValue()))
+    return;
 
-  return cast<ConstantSDNode>(VOffset)->getSExtValue() +
-         cast<ConstantSDNode>(SOffset)->getSExtValue() +
-         cast<ConstantSDNode>(Offset)->getSExtValue();
+  MMO->setOffset(cast<ConstantSDNode>(VOffset)->getSExtValue() +
+                 cast<ConstantSDNode>(SOffset)->getSExtValue() +
+                 cast<ConstantSDNode>(Offset)->getSExtValue());
 }
 
 SDValue SITargetLowering::lowerRawBufferAtomicIntrin(SDValue Op,
@@ -6839,13 +6835,21 @@
   };
 
   auto *M = cast<MemSDNode>(Op);
-  M->getMemOperand()->setOffset(getBufferOffsetForMMO(Ops[4], Ops[5], Ops[6]));
+  updateBufferMMO(M->getMemOperand(), Ops[4], Ops[5], Ops[6]);
 
   EVT MemVT = VData.getValueType();
   return DAG.getMemIntrinsicNode(NewOpcode, DL, Op->getVTList(), Ops, MemVT,
                                  M->getMemOperand());
 }
 
+// Return a value to use for the idxen operand by examining the vindex operand.
+static unsigned getIdxEn(SDValue VIndex) {
+  if (auto VIndexC = dyn_cast<ConstantSDNode>(VIndex))
+    // No need to set idxen if vindex is known to be zero.
+    return VIndexC->getZExtValue() != 0;
+  return 1;
+}
+
 SDValue
 SITargetLowering::lowerStructBufferAtomicIntrin(SDValue Op, SelectionDAG &DAG,
                                                 unsigned NewOpcode) const {
@@ -6866,8 +6870,7 @@
   };
 
   auto *M = cast<MemSDNode>(Op);
-  M->getMemOperand()->setOffset(getBufferOffsetForMMO(Ops[4], Ops[5], Ops[6],
-                                                      Ops[3]));
+  updateBufferMMO(M->getMemOperand(), Ops[4], Ops[5], Ops[6], Ops[3]);
 
   EVT MemVT = VData.getValueType();
   return DAG.getMemIntrinsicNode(NewOpcode, DL, Op->getVTList(), Ops, MemVT,
@@ -6980,9 +6983,7 @@
   case Intrinsic::amdgcn_buffer_load_format: {
     unsigned Glc = cast<ConstantSDNode>(Op.getOperand(5))->getZExtValue();
     unsigned Slc = cast<ConstantSDNode>(Op.getOperand(6))->getZExtValue();
-    unsigned IdxEn = 1;
-    if (auto Idx = dyn_cast<ConstantSDNode>(Op.getOperand(3)))
-      IdxEn = Idx->getZExtValue() != 0;
+    unsigned IdxEn = getIdxEn(Op.getOperand(3));
     SDValue Ops[] = {
       Op.getOperand(0), // Chain
       Op.getOperand(2), // rsrc
@@ -6993,11 +6994,7 @@
       DAG.getTargetConstant(Glc | (Slc << 1), DL, MVT::i32), // cachepolicy
       DAG.getTargetConstant(IdxEn, DL, MVT::i1), // idxen
     };
-
-    unsigned Offset = setBufferOffsets(Op.getOperand(4), DAG, &Ops[3]);
-    // We don't know the offset if vindex is non-zero, so clear it.
-    if (IdxEn)
-      Offset = 0;
+    setBufferOffsets(Op.getOperand(4), DAG, &Ops[3]);
 
     unsigned Opc = (IntrID == Intrinsic::amdgcn_buffer_load) ?
         AMDGPUISD::BUFFER_LOAD : AMDGPUISD::BUFFER_LOAD_FORMAT;
@@ -7005,7 +7002,7 @@
     EVT VT = Op.getValueType();
     EVT IntVT = VT.changeTypeToInteger();
     auto *M = cast<MemSDNode>(Op);
-    M->getMemOperand()->setOffset(Offset);
+    updateBufferMMO(M->getMemOperand(), Ops[3], Ops[4], Ops[5], Ops[2]);
     EVT LoadVT = Op.getValueType();
 
     if (LoadVT.getScalarType() == MVT::f16)
@@ -7037,7 +7034,7 @@
     };
 
     auto *M = cast<MemSDNode>(Op);
-    M->getMemOperand()->setOffset(getBufferOffsetForMMO(Ops[3], Ops[4], Ops[5]));
+    updateBufferMMO(M->getMemOperand(), Ops[3], Ops[4], Ops[5]);
     return lowerIntrinsicLoad(M, IsFormat, DAG, Ops);
   }
   case Intrinsic::amdgcn_struct_buffer_load:
@@ -7057,8 +7054,7 @@
     };
 
     auto *M = cast<MemSDNode>(Op);
-    M->getMemOperand()->setOffset(getBufferOffsetForMMO(Ops[3], Ops[4], Ops[5],
-                                                        Ops[2]));
+    updateBufferMMO(M->getMemOperand(), Ops[3], Ops[4], Ops[5], Ops[2]);
     return lowerIntrinsicLoad(cast<MemSDNode>(Op), IsFormat, DAG, Ops);
   }
   case Intrinsic::amdgcn_tbuffer_load: {
@@ -7069,9 +7065,7 @@
     unsigned Nfmt = cast<ConstantSDNode>(Op.getOperand(8))->getZExtValue();
     unsigned Glc = cast<ConstantSDNode>(Op.getOperand(9))->getZExtValue();
     unsigned Slc = cast<ConstantSDNode>(Op.getOperand(10))->getZExtValue();
-    unsigned IdxEn = 1;
-    if (auto Idx = dyn_cast<ConstantSDNode>(Op.getOperand(3)))
-      IdxEn = Idx->getZExtValue() != 0;
+    unsigned IdxEn = getIdxEn(Op.getOperand(3));
     SDValue Ops[] = {
       Op.getOperand(0),  // Chain
       Op.getOperand(2),  // rsrc
@@ -7152,9 +7146,7 @@
   case Intrinsic::amdgcn_buffer_atomic_xor:
   case Intrinsic::amdgcn_buffer_atomic_fadd: {
     unsigned Slc = cast<ConstantSDNode>(Op.getOperand(6))->getZExtValue();
-    unsigned IdxEn = 1;
-    if (auto Idx = dyn_cast<ConstantSDNode>(Op.getOperand(4)))
-      IdxEn = Idx->getZExtValue() != 0;
+    unsigned IdxEn = getIdxEn(Op.getOperand(4));
     SDValue Ops[] = {
       Op.getOperand(0), // Chain
       Op.getOperand(2), // vdata
@@ -7166,14 +7158,12 @@
       DAG.getTargetConstant(Slc << 1, DL, MVT::i32), // cachepolicy
       DAG.getTargetConstant(IdxEn, DL, MVT::i1), // idxen
     };
-    unsigned Offset = setBufferOffsets(Op.getOperand(5), DAG, &Ops[4]);
-    // We don't know the offset if vindex is non-zero, so clear it.
-    if (IdxEn)
-      Offset = 0;
+    setBufferOffsets(Op.getOperand(5), DAG, &Ops[4]);
+
     EVT VT = Op.getValueType();
 
     auto *M = cast<MemSDNode>(Op);
-    M->getMemOperand()->setOffset(Offset);
+    updateBufferMMO(M->getMemOperand(), Ops[4], Ops[5], Ops[6], Ops[3]);
     unsigned Opcode = 0;
 
     switch (IntrID) {
@@ -7296,9 +7286,7 @@
 
   case Intrinsic::amdgcn_buffer_atomic_cmpswap: {
     unsigned Slc = cast<ConstantSDNode>(Op.getOperand(7))->getZExtValue();
-    unsigned IdxEn = 1;
-    if (auto Idx = dyn_cast<ConstantSDNode>(Op.getOperand(5)))
-      IdxEn = Idx->getZExtValue() != 0;
+    unsigned IdxEn = getIdxEn(Op.getOperand(5));
     SDValue Ops[] = {
       Op.getOperand(0), // Chain
       Op.getOperand(2), // src
@@ -7311,13 +7299,11 @@
       DAG.getTargetConstant(Slc << 1, DL, MVT::i32), // cachepolicy
       DAG.getTargetConstant(IdxEn, DL, MVT::i1), // idxen
     };
-    unsigned Offset = setBufferOffsets(Op.getOperand(6), DAG, &Ops[5]);
-    // We don't know the offset if vindex is non-zero, so clear it.
-    if (IdxEn)
-      Offset = 0;
+    setBufferOffsets(Op.getOperand(6), DAG, &Ops[5]);
+
     EVT VT = Op.getValueType();
     auto *M = cast<MemSDNode>(Op);
-    M->getMemOperand()->setOffset(Offset);
+    updateBufferMMO(M->getMemOperand(), Ops[5], Ops[6], Ops[7], Ops[4]);
 
     return DAG.getMemIntrinsicNode(AMDGPUISD::BUFFER_ATOMIC_CMPSWAP, DL,
                                    Op->getVTList(), Ops, VT, M->getMemOperand());
@@ -7338,7 +7324,7 @@
     };
     EVT VT = Op.getValueType();
     auto *M = cast<MemSDNode>(Op);
-    M->getMemOperand()->setOffset(getBufferOffsetForMMO(Ops[5], Ops[6], Ops[7]));
+    updateBufferMMO(M->getMemOperand(), Ops[5], Ops[6], Ops[7]);
 
     return DAG.getMemIntrinsicNode(AMDGPUISD::BUFFER_ATOMIC_CMPSWAP, DL,
                                    Op->getVTList(), Ops, VT, M->getMemOperand());
@@ -7359,8 +7345,7 @@
     };
     EVT VT = Op.getValueType();
     auto *M = cast<MemSDNode>(Op);
-    M->getMemOperand()->setOffset(getBufferOffsetForMMO(Ops[5], Ops[6], Ops[7],
-                                                        Ops[4]));
+    updateBufferMMO(M->getMemOperand(), Ops[5], Ops[6], Ops[7], Ops[4]);
 
     return DAG.getMemIntrinsicNode(AMDGPUISD::BUFFER_ATOMIC_CMPSWAP, DL,
                                    Op->getVTList(), Ops, VT, M->getMemOperand());
@@ -7657,9 +7642,7 @@
     unsigned Nfmt = cast<ConstantSDNode>(Op.getOperand(9))->getZExtValue();
     unsigned Glc = cast<ConstantSDNode>(Op.getOperand(10))->getZExtValue();
     unsigned Slc = cast<ConstantSDNode>(Op.getOperand(11))->getZExtValue();
-    unsigned IdxEn = 1;
-    if (auto Idx = dyn_cast<ConstantSDNode>(Op.getOperand(4)))
-      IdxEn = Idx->getZExtValue() != 0;
+    unsigned IdxEn = getIdxEn(Op.getOperand(4));
     SDValue Ops[] = {
       Chain,
       VData,             // vdata
@@ -7737,9 +7720,7 @@
       VData = handleD16VData(VData, DAG);
     unsigned Glc = cast<ConstantSDNode>(Op.getOperand(6))->getZExtValue();
     unsigned Slc = cast<ConstantSDNode>(Op.getOperand(7))->getZExtValue();
-    unsigned IdxEn = 1;
-    if (auto Idx = dyn_cast<ConstantSDNode>(Op.getOperand(4)))
-      IdxEn = Idx->getZExtValue() != 0;
+    unsigned IdxEn = getIdxEn(Op.getOperand(4));
     SDValue Ops[] = {
       Chain,
       VData,
@@ -7751,15 +7732,13 @@
       DAG.getTargetConstant(Glc | (Slc << 1), DL, MVT::i32), // cachepolicy
       DAG.getTargetConstant(IdxEn, DL, MVT::i1), // idxen
     };
-    unsigned Offset = setBufferOffsets(Op.getOperand(5), DAG, &Ops[4]);
-    // We don't know the offset if vindex is non-zero, so clear it.
-    if (IdxEn)
-      Offset = 0;
+    setBufferOffsets(Op.getOperand(5), DAG, &Ops[4]);
+
     unsigned Opc = IntrinsicID == Intrinsic::amdgcn_buffer_store ?
                    AMDGPUISD::BUFFER_STORE : AMDGPUISD::BUFFER_STORE_FORMAT;
     Opc = IsD16 ? AMDGPUISD::BUFFER_STORE_FORMAT_D16 : Opc;
     MemSDNode *M = cast<MemSDNode>(Op);
-    M->getMemOperand()->setOffset(Offset);
+    updateBufferMMO(M->getMemOperand(), Ops[4], Ops[5], Ops[6], Ops[3]);
 
     // Handle BUFFER_STORE_BYTE/SHORT overloaded intrinsics
     EVT VDataType = VData.getValueType().getScalarType();
@@ -7806,7 +7785,7 @@
         IsFormat ? AMDGPUISD::BUFFER_STORE_FORMAT : AMDGPUISD::BUFFER_STORE;
     Opc = IsD16 ? AMDGPUISD::BUFFER_STORE_FORMAT_D16 : Opc;
     MemSDNode *M = cast<MemSDNode>(Op);
-    M->getMemOperand()->setOffset(getBufferOffsetForMMO(Ops[4], Ops[5], Ops[6]));
+    updateBufferMMO(M->getMemOperand(), Ops[4], Ops[5], Ops[6]);
 
     // Handle BUFFER_STORE_BYTE/SHORT overloaded intrinsics
     if (!IsD16 && !VDataVT.isVector() && EltType.getSizeInBits() < 32)
@@ -7853,8 +7832,7 @@
                    AMDGPUISD::BUFFER_STORE : AMDGPUISD::BUFFER_STORE_FORMAT;
     Opc = IsD16 ? AMDGPUISD::BUFFER_STORE_FORMAT_D16 : Opc;
     MemSDNode *M = cast<MemSDNode>(Op);
-    M->getMemOperand()->setOffset(getBufferOffsetForMMO(Ops[4], Ops[5], Ops[6],
-                                                        Ops[3]));
+    updateBufferMMO(M->getMemOperand(), Ops[4], Ops[5], Ops[6], Ops[3]);
 
     // Handle BUFFER_STORE_BYTE/SHORT overloaded intrinsics
     EVT VDataType = VData.getValueType().getScalarType();
@@ -7934,9 +7912,9 @@
 // Analyze a combined offset from an amdgcn_buffer_ intrinsic and store the
 // three offsets (voffset, soffset and instoffset) into the SDValue[3] array
 // pointed to by Offsets.
-unsigned SITargetLowering::setBufferOffsets(SDValue CombinedOffset,
-                                            SelectionDAG &DAG, SDValue *Offsets,
-                                            Align Alignment) const {
+void SITargetLowering::setBufferOffsets(SDValue CombinedOffset,
+                                        SelectionDAG &DAG, SDValue *Offsets,
+                                        Align Alignment) const {
   SDLoc DL(CombinedOffset);
   if (auto C = dyn_cast<ConstantSDNode>(CombinedOffset)) {
     uint32_t Imm = C->getZExtValue();
@@ -7946,7 +7924,7 @@
       Offsets[0] = DAG.getConstant(0, DL, MVT::i32);
       Offsets[1] = DAG.getConstant(SOffset, DL, MVT::i32);
       Offsets[2] = DAG.getTargetConstant(ImmOffset, DL, MVT::i32);
-      return SOffset + ImmOffset;
+      return;
     }
   }
   if (DAG.isBaseWithConstantOffset(CombinedOffset)) {
@@ -7959,13 +7937,12 @@
       Offsets[0] = N0;
       Offsets[1] = DAG.getConstant(SOffset, DL, MVT::i32);
       Offsets[2] = DAG.getTargetConstant(ImmOffset, DL, MVT::i32);
-      return 0;
+      return;
     }
   }
   Offsets[0] = CombinedOffset;
   Offsets[1] = DAG.getConstant(0, DL, MVT::i32);
   Offsets[2] = DAG.getTargetConstant(0, DL, MVT::i32);
-  return 0;
 }
 
 // Handle 8 bit and 16 bit buffer loads