Windows targets that use emutls add a "." character as a separator from the
_emutls_{t,v} and the true symbol name. However, exporting these symbol names
from a DLL is problematic (i.e. a thread local data variable), because the "."
in the symbol name tells the Windows loader to treat the symbol as a forwarding
RVA to a second DLL (in this case, it will look for the symbol "varname" in
__emutls_v.dll, the symbol exported is __emutls_v.varname). Note that this is
a runtime issue, not a compile/link issue.
This can be worked around by
#define TARGET_EMUTLS_VAR_PREFIX "__emutls_v_"
#define TARGET_EMUTLS_TMPL_PREFIX "__emutls_t_"
in the config header (e.g. config/i386/cygming.h or config/i386/mingw-w64.h,
etc).
However, this breaks backward compatibility with object files that were built
with previous versions of the compiler (e.g libold.a would have a global name
of __emutls_v.varname, while the patch would cause gcc to look for
__emutls_v_varname, which would cause linker errors).
--
Summary: Exporting emutls symbols from a DLL broken on w32
targets
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: dougsemler at gmail dot com
GCC target triplet: i686-pc-mingw32 x86_64-*-mingw32 i686-pc-cygwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44139
