[CLN-list] future GCC 4.3 and modules.h

[Richard B. Kreckel]

Hello Ralf,

On 2007-07-16, you wrote:
> Consider this code snippet:
> 
> extern "C" void func () {}
> __asm__("\t.globl " "_GLOBAL__I_" "func");
> static struct S {
>   inline S () { }
> } S;
> 
> On x86_64, with `g++-4.2 -fPIC -c a.cc', this results in
> | 0000000000000032 T _GLOBAL__I_func
> 
> with mainline GCC (what will eventually be 4.3 or some other number), it
> has
> | 0000000000000032 t _GLOBAL__I_a.cc
> 
> (and of course that will be `T' with the appropriate .globl directive).
> 
> This affects .libs/cl_DF_globals.o and some of the other globals
> objects, and causes a link failure of the examples due to the CL_REQUIRE
> undefined references (global constructor keyed to ...).
> 
> The hack below makes things work with mainline, but still needs to be
> redone properly, with a configure-time check and so on to not regress
> on g++ <= 4.2.  If you like I can take a stab at writing so; I assume
> the test should make use of $lt_compiler_pic_CXX and the header file
> provide different defines based on whether -DPIC was given?  (I'm not
> all that experienced with this stuff, so pointers are greatly
> appreciated.)

Can you write such a patch? I'm a little confused how to do the switch 
properly. Would it be bad to just combine #ifdef PIC and a test for 
__GNUC__ and __GNUC_MINOR__ inside modules.h? What is 
$lt_compiler_pic_CXX? It doesn't seem to exist.

> Index: include/cln/modules.h
> ===================================================================
> RCS file: /home/cvs/cln/include/cln/modules.h,v
> retrieving revision 1.19
> diff -u -r1.19 modules.h
> --- include/cln/modules.h	7 May 2006 21:05:24 -0000	1.19
> +++ include/cln/modules.h	26 May 2007 16:44:38 -0000
> @@ -219,7 +219,7 @@
>        };								\
>        static _CL_REQUIRE_CLASSNAME(module,__LINE__)			\
>          _CL_REQUIRE_CLASSNAME(module##_requirer,__LINE__);
> -  #else
> +  #elif 0
>      // gcc-3.0 -fuse-cxa-atexit doesn't have a single per-module destructor
>      // function anymore. Instead, for each object's static constructor it
>      // executes, it pushes the corresponding object's destructor onto a list.
> @@ -255,9 +255,42 @@
>        };								\
>        static _CL_REQUIRE_CLASSNAME(module,__LINE__)			\
>          _CL_REQUIRE_CLASSNAME(module##_requirer,__LINE__);
> -  #endif
>    #define _CL_REQUIRE_CLASSNAME(module,line) __CL_REQUIRE_CLASSNAME(module,line)
>    #define __CL_REQUIRE_CLASSNAME(module,line) cl_module__##module##__##line
> +  #else
> +    #define CL_PROVIDE(module)  \
> +      extern "C" void cl_module__##module##__ctorend (void);		\
> +      CL_GLOBALIZE_JUMP_LABEL(cl_module__##module##__ctorend)		\
> +      CL_GLOBALIZE_CTORDTOR_LABEL(					\
> +                 ASM_UNDERSCORE_PREFIX CL_GLOBAL_CONSTRUCTOR_PREFIX	\
> +                 #module ".cc")		\
> +      static int cl_module__##module##__counter;			\
> +      struct cl_module__##module##__controller {			\
> +        inline cl_module__##module##__controller ()			\
> +          { if (cl_module__##module##__counter++)			\
> +              { CL_JUMP_TO(cl_module__##module##__ctorend); }		\
> +          }								\
> +      };								\
> +      static cl_module__##module##__controller cl_module__##module##__ctordummy;
> +    #define CL_PROVIDE_END(module)  \
> +      struct cl_module__##module##__destroyer {				\
> +        inline cl_module__##module##__destroyer ()			\
> +          { CL_OUTPUT_LABEL (ASM_UNDERSCORE_PREFIX "cl_module__" #module "__ctorend"); } \
> +      };								\
> +      static cl_module__##module##__destroyer cl_module__##module##__dtordummy;
> +    #define CL_REQUIRE(module)  \
> +      extern "C" void cl_module__##module##__ctor (void)		\
> +        __asm__ (ASM_UNDERSCORE_PREFIX CL_GLOBAL_CONSTRUCTOR_PREFIX	\
> +                 #module ".cc");		\
> +      struct _CL_REQUIRE_CLASSNAME(module,__LINE__) {			\
> +        inline _CL_REQUIRE_CLASSNAME(module,__LINE__) ()		\
> +          { cl_module__##module##__ctor (); }				\
> +      };								\
> +      static _CL_REQUIRE_CLASSNAME(module,__LINE__)			\
> +        _CL_REQUIRE_CLASSNAME(module##_requirer,__LINE__);
> +  #define _CL_REQUIRE_CLASSNAME(module,line) __CL_REQUIRE_CLASSNAME(module,line)
> +  #define __CL_REQUIRE_CLASSNAME(module,line) cl_module__##module##__##line
> +#endif
>  #else
>    #define CL_PROVIDE(module)
>    #define CL_PROVIDE_END(module)

Cheers
   -richy.
-- 
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>