a tricky problem in relocation for coffwriter

Dear there,

For a code like this:

unsigned long *Local1;
typedef struct
unsigned long local1;

static void set(spcstype *statsptr){

And I get error in my own backend:
WinCoffObjectWriter::recordRelocation, lib/mc/wincoffobjectwriter.cpp, line 770.

However, after I changed the name of Local1 to dLocal1, the problem disappeared. In my backend I’m simply using hi+lo to handle all the global relocations. Can anyone point to me any place to look at? I truly have no clues on how to fix it…