On Sun, Jun 04, 2006 at 07:05:55AM -0400, Ross Ridge wrote: > FX Coudert wrote: > > Now, for an idea of how much work it represents... perhaps someone > >here can tell us? > > It's not too hard but it requires changing GCC and binutils, plus a > bit of library support. In my implementation (more or less finished, > but I have had time to test it yet), I did the following: > > - Used the existing __thread support in the front-end. Silently > ignore the ELF TLS models, because Windows only has one model. > - Added target specific (cygming) support for __attribute__((thread)) > aka __declspec(thread) for MSC compatibility. > - Created an legitimize_win32_tls_address() to replace > legitimize_tls_address() in i386.c. It outputs RTL like: > (set (reg:SI tp) (mem:SI (unspec [(const_int 44)] WIN32_TIB))) > (set (reg:SI index) (mem:SI (symbol_ref:SI "__tls_index__"))) > (set (reg:SI base) (mem:SI (add:SI (reg:SI tp) > (mult:SI (reg:SI index) > (const_int 4))))) > (plus:SI (reg:SI base) > (const:SI (unspec:SI [(symbol_ref:SI "foo")] > SECREL)))) > - Handled the WIN32_TIB unspec by outputting "%fs:44" and the > SECREL unspec by outputting "foo`SECREL". I couldn't use > "[EMAIL PROTECTED]" because "@" is valid in identifiers with PECOFF. > - Support .tls sections in PECOFF by creating an > i386_pe_select_section() based on the generic ELF version. > - Added an -mfiber-safe-tls target specific option that makes > the references to the WIN32 TIB non-constant. > - Modified gas to handle "foo`SECREL", based on the ELF support > for "@" relocations > - Fixed some problems with TLS handling in the PECOFF linker > script > - Created an object file that defines the __tls_used structure > (and thus the TLS directory entry) and __tls_index__.
Excellent. Pretty much exactly what I had in mind. > Actually, the last one I haven't done yet. I've just been using a linker > script to do that, but it should be in a library so the TLS directory > entry isn't created if the executable doesn't use TLS. You can also create this in the linker, without a library. Not too difficult, since you've got to do that to set the bit in the PE header anyway. r~
