--- /dev/null
+; RUN: llc -march=amdgcn -mcpu=SI -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=GCN -check-prefix=SI-NOHSA -check-prefix=GCN-NOHSA -check-prefix=FUNC %s
+; RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck -check-prefix=VI -check-prefix=VI-NOHSA -check-prefix=GCN -check-prefix=GCN-NOHSA -check-prefix=FUNC %s
+; RUN: llc -march=r600 -mcpu=redwood < %s | FileCheck -check-prefix=EG -check-prefix=FUNC %s
+
+; FUNC-LABEL: {{^}}read_workdim:
+; EG: MEM_RAT_CACHELESS STORE_RAW [[VAL:T[0-9]+\.X]]
+; EG: MOV [[VAL]], KC0[2].Z
+
+; SI-NOHSA: s_load_dword [[VAL:s[0-9]+]], s[0:1], 0xb
+; VI-NOHSA: s_load_dword [[VAL:s[0-9]+]], s[0:1], 0x2c
+; GCN-NOHSA: v_mov_b32_e32 [[VVAL:v[0-9]+]], [[VAL]]
+; GCN-NOHSA: buffer_store_dword [[VVAL]]
+define void @read_workdim(i32 addrspace(1)* %out) {
+entry:
+ %0 = call i32 @llvm.AMDGPU.read.workdim() #0
+ store i32 %0, i32 addrspace(1)* %out
+ ret void
+}
+
+; FUNC-LABEL: {{^}}read_workdim_known_bits:
+; SI: s_load_dword [[VAL:s[0-9]+]], s[0:1], 0xb
+; VI: s_load_dword [[VAL:s[0-9]+]], s[0:1], 0x2c
+; GCN-NOT: 0xff
+; GCN: v_mov_b32_e32 [[VVAL:v[0-9]+]], [[VAL]]
+; GCN: buffer_store_dword [[VVAL]]
+define void @read_workdim_known_bits(i32 addrspace(1)* %out) {
+entry:
+ %dim = call i32 @llvm.AMDGPU.read.workdim() #0
+ %shl = shl i32 %dim, 24
+ %shr = lshr i32 %shl, 24
+ store i32 %shr, i32 addrspace(1)* %out
+ ret void
+}
+
+declare i32 @llvm.AMDGPU.read.workdim() #0
+
+attributes #0 = { readnone }