ios_base.h: Use _Atomic_word for reference counts.

	libstdc++/5432
	* include/bits/ios_base.h: Use _Atomic_word for reference counts.
	* include/bits/localefwd.h: Likewise.
	Also use for std::locale::id::_S_highwater.
	* src/ios.cc (ios_base::xalloc): Use _Atomic_word.
	* src/locale.cc: Support new usage of _Atomic_word.
	(std::locale::classic): Guard entire function against reentry.
	* src/localename.cc: Support new usage of _Atomic_word.

From-SVN: r49195

3 files changed, 18 insertions, 10 deletions

diff --git a/libstdc++-v3/src/ios.cc b/libstdc++-v3/src/ios.cc
index 6ca59572fba..e8122bb2b77 100644
--- a/libstdc++-v3/src/ios.cc
+++ b/libstdc++-v3/src/ios.cc
@@ -1,6 +1,7 @@
 // Iostreams base classes -*- C++ -*-
 
-// Copyright (C) 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
+// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002
+// Free Software Foundation, Inc.
 //
 // This file is part of the GNU ISO C++ Library.  This library is free
 // software; you can redistribute it and/or modify it under the
@@ -36,6 +37,8 @@
 #include <istream>
 #include <fstream>
 
+#include <bits/atomicity.h>
+
 namespace std 
 {
   // Extern declarations for global objects in src/globals.cc.
@@ -224,10 +227,11 @@ namespace std
   int 
   ios_base::xalloc() throw()
   {
-    // XXX MT
     // XXX should be a symbol. (Reserve 0..3 for builtins.)
-    static int top = 4; 
-    return top++;
+    static _Atomic_word top = 0; 
+    return __exchange_and_add(&top, 1) + 4;
+    // Implementation note: Initialize top to zero to ensure that
+    // initialization occurs before main() is started.
   }
 
   // 27.4.2.5  iword/pword storage
diff --git a/libstdc++-v3/src/locale.cc b/libstdc++-v3/src/locale.cc
index 630805ee0fa..52091827259 100644
--- a/libstdc++-v3/src/locale.cc
+++ b/libstdc++-v3/src/locale.cc
@@ -41,6 +41,8 @@
 # include <cwctype>     // for towupper, etc.
 #endif
 
+#include <bits/atomicity.h>
+
 namespace std 
 {
   // Defined in globals.cc.
@@ -72,7 +74,7 @@ namespace std
 #endif
 
   // Definitions for static const data members of locale::id
-  size_t locale::id::_S_highwater;  // init'd to 0 by linker
+  _Atomic_word locale::id::_S_highwater;  // init'd to 0 by linker
 
   // Definitions for static const data members of locale::_Impl
   const locale::id* const
@@ -187,7 +189,7 @@ namespace std
   { 
     _S_initialize(); 
     (_M_impl = _S_global)->_M_add_reference(); 
-  } // XXX MT
+  }
 
   locale::locale(const locale& __other) throw()
   { (_M_impl = __other._M_impl)->_M_add_reference(); }
@@ -283,7 +285,9 @@ namespace std
   locale const&
   locale::classic()
   {
-    // XXX MT
+    static _STL_mutex_lock __lock __STL_MUTEX_INITIALIZER;
+    _STL_auto_lock __auto(__lock);
+
     if (!_S_classic)
       {
 	try 
@@ -364,13 +368,13 @@ namespace std
   void  
   locale::facet::
   _M_add_reference() throw()
-  { ++_M_references; }  // XXX MT
+  { __atomic_add(&_M_references, 1); }
 
   void  
   locale::facet::
   _M_remove_reference() throw()
   {
-    if (_M_references-- == 0)
+    if (__exchange_and_add(&_M_references, -1) == 0)
       {
         try 
 	  { delete this; }  
diff --git a/libstdc++-v3/src/localename.cc b/libstdc++-v3/src/localename.cc
index 45c4732d007..816f7581c12 100644
--- a/libstdc++-v3/src/localename.cc
+++ b/libstdc++-v3/src/localename.cc
@@ -178,7 +178,7 @@ namespace std
       {
 	size_t& __index = __idp->_M_index;
 	if (!__index)
-	  __index = ++locale::id::_S_highwater;  // XXX MT
+	  __index = 1 + __exchange_and_add(&locale::id::_S_highwater, 1);
 	
 	if (__index >= _M_facets->size())
 	  _M_facets->resize(__index + 1, 0);  // might throw