http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55268
--- Comment #1 from SquallATF <squallatf at gmail dot com> 2012-11-11 11:05:58 UTC --- I found the reason, TARGET_MANGLE_DECL_ASSEMBLER_NAME is defined to ix86_mangle_decl_assembler_name in gcc/config/i386/i386.c overide the define i386_pe_mangle_decl_assembler_name in gcc/config/i386/cygming.h