*ping* generic atomicity.h

[Danny Smith]

The patch presented here:
 
    http://gcc.gnu.org/ml/libstdc++/2002-12/msg00015.html

does not work on i386-pc-mingw32 which does need
 __GTHREAD_MUTEX_INIT_FUNCTION.

The main problem is with lack of support for __attribute__((weak)) but
there are other problmes as well. See annotated patch below, 

Another query:
cpu_include_dir defaults to the cpu part of the target triplet.
But doesn't that correspond to the -mcpu or -mtune default rather than
to the -march default. In the case of generic vs i486 atomicity.h, the
selection should be based on the default instruction set -- which is
 __i386__ -- not the default tuning?? 

>
>What do you think?
>
> 
>Index: config/cpu/generic/atomicity.h
>===================================================================
>RCS file:
/home/pme/Repositories/GCC/gcc/libstdc++-v3/config/cpu/generic/atomicity.h,v
>retrieving revision 1.4
>diff -u -r1.4 atomicity.h
>--- config/cpu/generic/atomicity.h	8 Nov 2002 19:24:41 -0000	1.4
>+++ config/cpu/generic/atomicity.h	26 Nov 2002 18:36:59 -0000
>@@ -37,19 +37,34 @@
> namespace __gnu_cxx
> {
>   __gthread_mutex_t _Atomic_add_mutex __attribute__ ((__weak__))
>-                                                      = __GTHREAD_MUTEX_INIT;
>+#ifdef __GTHREAD_MUTEX_INIT
>+                                                      = __GTHREAD_MUTEX_INIT
>+#endif


__attribute__((weak)) is not supported on i386-pc-mingw or cygwin, hence get
multiple definition problem.  Make extern declaration and define in
src/misc-inst.cc??


>+                                                      ;
>+
>+#ifndef __GTHREAD_MUTEX_INIT
>+  #define __GTHREAD_NEED_MUTEX_ONCE_FUNCTION
>+  __gthread_once_t _Atomic_add_mutex_once __attribute__ ((__weak__))
>+                                                     = __GTHREAD_ONCE_INIT;

Ditto.

>+  static void __gthread_atomic_add_mutex_once();

static function declaration, but missing definition when included by
any file _except_ src/misc-inst.cc.   Should this function be inlined here
rather than definition in src/misc-inst.cc.

==snip===;

>Index: src/misc-inst.cc
>===================================================================
>RCS file: /home/pme/Repositories/GCC/gcc/libstdc++-v3/src/misc-inst.cc,v
>retrieving revision 1.20
>diff -u -r1.20 misc-inst.cc
>--- src/misc-inst.cc	5 Nov 2002 19:17:37 -0000	1.20
>+++ src/misc-inst.cc	26 Nov 2002 18:36:05 -0000
>@@ -87,3 +87,14 @@
>      string*, __false_type);
> #endif
> } // namespace std
>+
>+namespace __gnu_cxx
>+{
>+  #ifdef __GTHREAD_NEED_MUTEX_ONCE_FUNCTION
>+  // generic atomicity.h without static initialization
>+  static void __gthread_atomic_add_mutex_once()
>+  {
>+    __GTHREAD_MUTEX_INIT_FUNCTION (_Atomic_add_mutex);

Should be  __GTHREAD_MUTEX_INIT_FUNCTION (&_Atomic_add_mutex), as per
description in gthr.h and implementation in, eg., gthr-win32.h.


Danny

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