Index: llvm/lib/Target/AMDGPU/SIISelLowering.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -9043,9 +9043,10 @@
     }
 
     return SDValue();
-  } else {
-    llvm_unreachable("unhandled address space");
   }
+
+  // Probably an invalid store. If so we'll end up emitting a selection error.
+  return SDValue();
 }
 
 SDValue SITargetLowering::LowerTrig(SDValue Op, SelectionDAG &DAG) const {
Index: llvm/test/CodeGen/AMDGPU/store-to-constant-error.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/store-to-constant-error.ll
@@ -0,0 +1,10 @@
+; RUN: not --crash llc -global-isel=0 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -o /dev/null %s 2>&1 | FileCheck -check-prefix=SDAG %s
+; RUN: not --crash llc -global-isel=1 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -o /dev/null %s 2>&1 | FileCheck -check-prefix=GISEL %s
+
+; SDAG: LLVM ERROR: Cannot select: t{{[0-9]+}}: ch = store<(store (s32) into %ir.ptr.load, addrspace 4)>
+; GISEL: LLVM ERROR: cannot select: G_STORE %{{[0-9]+}}:vgpr(s32), %{{[0-9]+}}:vgpr(p4) :: (store (s32) into %ir.ptr.load, addrspace 4) (in function: store_to_constant_i32)
+define amdgpu_kernel void @store_to_constant_i32(i32 addrspace(4)* %ptr) {
+bb:
+  store i32 1, i32 addrspace(4)* %ptr, align 4
+  ret void
+}