AMDGPU: Avoid relying on an undef value in test

This was really becoming a direct call during the DAG, so it wasn't as
true to the test purpose.

Author: arsenm

llvm/test/CodeGen/AMDGPU/indirect-call-known-callees.ll

@@ -7,10 +7,12 @@
 ; FIXME: Passing real values for workitem ID, and 0s that can be undef
 
 ; CHECK-LABEL: indirect_call_known_no_special_inputs:
-; CHECK: s_mov_b64 s[8:9], 0
-; CHECK: s_mov_b32 s12, s6
-; CHECK: v_mov_b32_e32 v31, v0
-; CHECK: s_swappc_b64
+
+; CHECK-DAG: s_cselect_b64 [[CALL_TARGET:s\[[0-9]+:[0-9]+\]]]
+; CHECK-DAG: s_mov_b64 s[8:9], 0
+; CHECK-DAG: s_mov_b32 s12, s6
+; CHECK-DAG: v_mov_b32_e32 v31, v0
+; CHECK: s_swappc_b64 s[30:31], [[CALL_TARGET]]
 
 ; CHECK: .amdhsa_kernarg_size 0
 ; CHECK-NEXT: .amdhsa_user_sgpr_private_segment_buffer 1
@@ -28,7 +30,8 @@
 ; CHECK-NEXT: .amdhsa_system_vgpr_workitem_id 0
 define amdgpu_kernel void @indirect_call_known_no_special_inputs() {
 bb:
-  %tmp = select i1 undef, void (i8*, i32, i8*)* bitcast (void ()* @wobble to void (i8*, i32, i8*)*), void (i8*, i32, i8*)* bitcast (void ()* @snork to void (i8*, i32, i8*)*)
+  %cond = load i1, i1 addrspace(4)* null
+  %tmp = select i1 %cond, void (i8*, i32, i8*)* bitcast (void ()* @wobble to void (i8*, i32, i8*)*), void (i8*, i32, i8*)* bitcast (void ()* @snork to void (i8*, i32, i8*)*)
   call void %tmp(i8* undef, i32 undef, i8* undef)
   ret void
 }