Hi, So let’s ignore the questions for now - OK for the non-Darwin parts of the patch ?
> On 24 Sep 2021, at 17:57, Iain Sandoe <i...@sandoe.co.uk> wrote: > > as noted below the non-Darwin parts of this are trivial (and a no-OP). > I’d like to apply this to start work towards solving Darwin’s libgcc issues, >> On 20 Sep 2021, at 09:25, Iain Sandoe <i...@sandoe.co.uk> wrote: >> >> The non-Darwin part of this patch is trivial but raises a couple of questions >> >> A/ >> We define builtins to support emulated TLS. >> These are defined with void * pointers >> The implementation (in libgcc) uses the correct type (struct __emutls_object >> *) >> in both a forward declaration of the functions and in thier eventual >> implementation. >> >> This leads to a (long-standing, nothing new) complaint at build-time about >> the mismatch in the builtin/implementation decls. >> >> AFAICT, there’s no way to fix that unless we introduce struct >> __emutls_object * >> as a built-in type? >> >> B/ >> It seems that a consequence of the mismatch in decls means that if I apply >> attributes to the decl (in the implementation file), they are ignored and I >> have >> to apply them to the definition in order for this to work. >> >> This (B) is what the patch below does. >> >> tested on powerpc,i686,x86_64-darwin, x86_64-linux >> OK for master? >> thanks, >> Iain >> >> If the current situation is that A or B indicates “there’s a bug”, please >> could that >> be considered as distinct from the current patch (which doesn’t alter this >> in any >> way) so that we can make progress on fixing Darwin libgcc issues. >> >> ===== commit log >> >> In order to better support use of the emulated TLS between objects with >> DSO dependencies and static-linked libgcc, allow a target to make weak >> definitions. >> >> Signed-off-by: Iain Sandoe <i...@sandoe.co.uk> >> >> libgcc/ChangeLog: >> >> * config.host: Add weak-defined emutls crt. >> * config/t-darwin: Build weak-defined emutls objects. >> * emutls.c (__emutls_get_address): Add optional attributes. >> (__emutls_register_common): Likewise. >> (EMUTLS_ATTR): New. >> --- >> libgcc/config.host | 2 +- >> libgcc/config/t-darwin | 13 +++++++++++++ >> libgcc/emutls.c | 17 +++++++++++++++-- >> 3 files changed, 29 insertions(+), 3 deletions(-) >> >> diff --git a/libgcc/config.host b/libgcc/config.host >> index 6c34b13d611..a447ac7ae30 100644 >> --- a/libgcc/config.host >> +++ b/libgcc/config.host >> @@ -215,7 +215,7 @@ case ${host} in >> *-*-darwin*) >> asm_hidden_op=.private_extern >> tmake_file="$tmake_file t-darwin ${cpu_type}/t-darwin t-libgcc-pic >> t-slibgcc-darwin" >> - extra_parts="crt3.o libd10-uwfef.a crttms.o crttme.o" >> + extra_parts="crt3.o libd10-uwfef.a crttms.o crttme.o libemutls_w.a" >> ;; >> *-*-dragonfly*) >> tmake_file="$tmake_file t-crtstuff-pic t-libgcc-pic t-eh-dw2-dip" >> diff --git a/libgcc/config/t-darwin b/libgcc/config/t-darwin >> index 14ae6b35a4e..d6f688d66d5 100644 >> --- a/libgcc/config/t-darwin >> +++ b/libgcc/config/t-darwin >> @@ -15,6 +15,19 @@ crttme.o: $(srcdir)/config/darwin-crt-tm.c >> LIB2ADDEH = $(srcdir)/unwind-dw2.c $(srcdir)/config/unwind-dw2-fde-darwin.c \ >> $(srcdir)/unwind-sjlj.c $(srcdir)/unwind-c.c >> >> +# Make emutls weak so that we can deal with -static-libgcc, override the >> +# hidden visibility when this is present in libgcc_eh. >> +emutls.o: HOST_LIBGCC2_CFLAGS += \ >> + -DEMUTLS_ATTR='__attribute__((__weak__,__visibility__("default")))' >> +emutls_s.o: HOST_LIBGCC2_CFLAGS += \ >> + -DEMUTLS_ATTR='__attribute__((__weak__,__visibility__("default")))' >> + >> +# Make the emutls crt as a convenience lib so that it can be linked >> +# optionally, use the shared version so that we can link with DSO. >> +libemutls_w.a: emutls_s.o >> + $(AR_CREATE_FOR_TARGET) $@ $< >> + $(RANLIB_FOR_TARGET) $@ >> + >> # Patch to __Unwind_Find_Enclosing_Function for Darwin10. >> d10-uwfef.o: $(srcdir)/config/darwin10-unwind-find-enc-func.c >> $(crt_compile) -mmacosx-version-min=10.6 -c $< >> diff --git a/libgcc/emutls.c b/libgcc/emutls.c >> index ed2658170f5..d553a74728f 100644 >> --- a/libgcc/emutls.c >> +++ b/libgcc/emutls.c >> @@ -50,7 +50,16 @@ struct __emutls_array >> void **data[]; >> }; >> >> +/* EMUTLS_ATTR is provided to allow targets to build the emulated tls >> + routines as weak definitions, for example. >> + If there is no definition, fall back to the default. */ >> +#ifndef EMUTLS_ATTR >> +# define EMUTLS_ATTR >> +#endif >> + >> +EMUTLS_ATTR >> void *__emutls_get_address (struct __emutls_object *); >> +EMUTLS_ATTR >> void __emutls_register_common (struct __emutls_object *, word, word, void *); >> >> #ifdef __GTHREADS >> @@ -123,7 +132,11 @@ emutls_alloc (struct __emutls_object *obj) >> return ret; >> } >> >> -void * >> +/* Despite applying the attribute to the declaration, in this case the mis- >> + match between the builtin's declaration [void * (*)(void *)] and the >> + implementation here, causes the decl. attributes to be discarded. */ >> + >> +EMUTLS_ATTR void * >> __emutls_get_address (struct __emutls_object *obj) >> { >> if (! __gthread_active_p ()) >> @@ -187,7 +200,7 @@ __emutls_get_address (struct __emutls_object *obj) >> #endif >> } >> >> -void >> +EMUTLS_ATTR void >> __emutls_register_common (struct __emutls_object *obj, >> word size, word align, void *templ) >> { >> -- >> >