Index: lib/Target/AMDGPU/SIISelLowering.cpp
===================================================================
--- lib/Target/AMDGPU/SIISelLowering.cpp
+++ lib/Target/AMDGPU/SIISelLowering.cpp
@@ -2156,21 +2156,25 @@
                          MachineMemOperand::MOInvariant);
 }
 
+// FIXME: Really support non-0 null pointers.
+static int getSegmentNullPtrValue(unsigned AS) {
+  return AS == AMDGPUAS::LOCAL_ADDRESS ? -1 : 0;
+}
+
 SDValue SITargetLowering::lowerADDRSPACECAST(SDValue Op,
                                              SelectionDAG &DAG) const {
   SDLoc SL(Op);
   const AddrSpaceCastSDNode *ASC = cast<AddrSpaceCastSDNode>(Op);
 
   SDValue Src = ASC->getOperand(0);
-
-  // FIXME: Really support non-0 null pointers.
-  SDValue SegmentNullPtr = DAG.getConstant(-1, SL, MVT::i32);
   SDValue FlatNullPtr = DAG.getConstant(0, SL, MVT::i64);
 
   // flat -> local/private
   if (ASC->getSrcAddressSpace() == AMDGPUAS::FLAT_ADDRESS) {
-    if (ASC->getDestAddressSpace() == AMDGPUAS::LOCAL_ADDRESS ||
-        ASC->getDestAddressSpace() == AMDGPUAS::PRIVATE_ADDRESS) {
+    unsigned DestAS = ASC->getDestAddressSpace();
+    if (DestAS == AMDGPUAS::LOCAL_ADDRESS || DestAS == AMDGPUAS::PRIVATE_ADDRESS) {
+      SDValue SegmentNullPtr
+        = DAG.getConstant(getSegmentNullPtrValue(DestAS), SL, MVT::i32);
       SDValue NonNull = DAG.getSetCC(SL, MVT::i1, Src, FlatNullPtr, ISD::SETNE);
       SDValue Ptr = DAG.getNode(ISD::TRUNCATE, SL, MVT::i32, Src);
 
@@ -2181,8 +2185,11 @@
 
   // local/private -> flat
   if (ASC->getDestAddressSpace() == AMDGPUAS::FLAT_ADDRESS) {
-    if (ASC->getSrcAddressSpace() == AMDGPUAS::LOCAL_ADDRESS ||
-        ASC->getSrcAddressSpace() == AMDGPUAS::PRIVATE_ADDRESS) {
+    unsigned SrcAS = ASC->getSrcAddressSpace();
+    if (SrcAS == AMDGPUAS::LOCAL_ADDRESS || SrcAS == AMDGPUAS::PRIVATE_ADDRESS) {
+      SDValue SegmentNullPtr
+        = DAG.getConstant(getSegmentNullPtrValue(SrcAS), SL, MVT::i32);
+
       SDValue NonNull
         = DAG.getSetCC(SL, MVT::i1, Src, SegmentNullPtr, ISD::SETNE);
 
Index: test/CodeGen/AMDGPU/addrspacecast.ll
===================================================================
--- test/CodeGen/AMDGPU/addrspacecast.ll
+++ test/CodeGen/AMDGPU/addrspacecast.ll
@@ -34,7 +34,7 @@
 ; HSA-DAG: v_mov_b32_e32 [[VAPERTURE:v[0-9]+]], [[APERTURE]]
 ; HSA-DAG: v_mov_b32_e32 [[VPTR:v[0-9]+]], [[PTR]]
 
-; HSA-DAG: v_cmp_ne_u32_e64 vcc, [[PTR]], -1
+; HSA-DAG: v_cmp_ne_u32_e64 vcc, [[PTR]], 0
 ; HSA-DAG: v_cndmask_b32_e32 v[[HI:[0-9]+]], 0, [[VAPERTURE]]
 ; HSA-DAG: v_cndmask_b32_e32 v[[LO:[0-9]+]], 0, [[VPTR]]
 ; HSA-DAG: v_mov_b32_e32 [[K:v[0-9]+]], 7
@@ -98,7 +98,7 @@
 ; HSA: s_load_dwordx2 s{{\[}}[[PTR_LO:[0-9]+]]:[[PTR_HI:[0-9]+]]{{\]}}
 ; HSA-DAG: v_cmp_ne_u64_e64 vcc, s{{\[}}[[PTR_LO]]:[[PTR_HI]]{{\]}}, 0{{$}}
 ; HSA-DAG: v_mov_b32_e32 v[[VPTR_LO:[0-9]+]], s[[PTR_LO]]
-; HSA-DAG: v_cndmask_b32_e32 [[CASTPTR:v[0-9]+]], -1, v[[VPTR_LO]]
+; HSA-DAG: v_cndmask_b32_e32 [[CASTPTR:v[0-9]+]], 0, v[[VPTR_LO]]
 ; HSA-DAG: v_mov_b32_e32 v[[K:[0-9]+]], 0{{$}}
 ; HSA: buffer_store_dword v[[K]], [[CASTPTR]], s{{\[[0-9]+:[0-9]+\]}}, s{{[0-9]+}} offen{{$}}
 define void @use_flat_to_private_addrspacecast(i32 addrspace(4)* %ptr) #0 {
@@ -176,10 +176,9 @@
 }
 
 ; HSA-LABEL: {{^}}cast_0_private_to_flat_addrspacecast:
-; HSA: s_load_dword [[APERTURE:s[0-9]+]], s[4:5], 0x11
-; HSA-DAG: v_mov_b32_e32 v[[HI:[0-9]+]], [[APERTURE]]
-; HSA-DAG: v_mov_b32_e32 v[[LO:[0-9]+]], 0{{$}}
+; HSA: v_mov_b32_e32 v[[LO:[0-9]+]], 0{{$}}
 ; HSA-DAG: v_mov_b32_e32 v[[K:[0-9]+]], 7{{$}}
+; HSA-DAG: v_mov_b32_e32 v[[HI:[0-9]+]], 0{{$}}
 ; HSA: flat_store_dword v{{\[}}[[LO]]:[[HI]]{{\]}}, v[[K]]
 define void @cast_0_private_to_flat_addrspacecast() #0 {
   %cast = addrspacecast i32* null to i32 addrspace(4)*
@@ -188,7 +187,7 @@
 }
 
 ; HSA-LABEL: {{^}}cast_0_flat_to_private_addrspacecast:
-; HSA-DAG: v_mov_b32_e32 [[PTR:v[0-9]+]], -1{{$}}
+; HSA-DAG: v_mov_b32_e32 [[PTR:v[0-9]+]], 0{{$}}
 ; HSA-DAG: v_mov_b32_e32 [[K:v[0-9]+]], 7{{$}}
 ; HSA: buffer_store_dword [[K]], [[PTR]], s{{\[[0-9]+:[0-9]+\]}}, s{{[0-9]+}} offen
 define void @cast_0_flat_to_private_addrspacecast() #0 {