C++ PATCH for memory corruption

[mark at codesourcery dot com]

The following patch fixes a bug on code like:

  template <class T>
  struct S1 {
    S1 (T = T (0));
  };

  template <class T>
  inline void f () {
    S1<T> s;
    S1<T*> s2;
  }

  struct S2 {
    void g();
  };

  void g() 
  {
    f<int>();
  }

  void S2::g () {}

Here, we would (upon instantiation of `f'), push to the top-level
saving away the cached `previous_class_values' for `S2'.  Then, we'd
free the obstack containing them when instantiating the objects
declared inside `f'.

Installed on the mainline and on the branch.

--
Mark Mitchell                   mark@codesourcery.com
CodeSourcery, LLC               http://www.codesourcery.com

1999-06-15  Mark Mitchell  <mark@codesourcery.com>

	* cp-tree.h (class_cache_firstobj): Declare.
	(maybe_push_cache_obstack): Rename to push_cache_obstack.
	* class.c (permanent_obstack): Remove declaration.
	(class_cache_firstobj): Make it global.
	(add_method): Don't use permanent_obstack directly.
	(pushclass): Only free the class_cache_obstack if we know how far
	back to free it.
	(maybe_push_cache_obstack): Rename to push_cache_obstack.
	* decl.c: Remove dead comment.
	(saved_scope): Add class_cache_firstobj.
	(push_to_top_level): Save it.
	(pop_from_top_level): Restore it.
	(push_class_level_binding): Use push_cache_obstack, not
	maybe_push_cache_obstack.
	* search.c (push_class_decls): Likewise.
	
Index: cp-tree.h
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/gcc/cp/cp-tree.h,v
retrieving revision 1.237
diff -u -p -r1.237 cp-tree.h
--- cp-tree.h	1999/05/25 15:31:27	1.237
+++ cp-tree.h	1999/06/15 23:00:14
@@ -2253,6 +2253,9 @@ extern int current_class_depth;
 extern tree current_lang_name;
 extern tree lang_name_cplusplus, lang_name_c, lang_name_java;
 
+/* The low-water mark on the class-cache obstack.  */
+extern char *class_cache_firstobj;
+
 /* Points to the name of that function. May not be the DECL_NAME
    of CURRENT_FUNCTION_DECL due to overloading */
 extern tree original_function_name;
@@ -2744,7 +2747,7 @@ extern void push_lang_context			PROTO((t
 extern void pop_lang_context			PROTO((void));
 extern tree instantiate_type			PROTO((tree, tree, int));
 extern void print_class_statistics		PROTO((void));
-extern void maybe_push_cache_obstack		PROTO((void));
+extern void push_cache_obstack		        PROTO((void));
 extern unsigned HOST_WIDE_INT skip_rtti_stuff	PROTO((tree *, tree));
 extern void build_self_reference		PROTO((void));
 extern void warn_hidden				PROTO((tree));
Index: class.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/gcc/cp/class.c,v
retrieving revision 1.161
diff -u -p -r1.161 class.c
--- class.c	1999/06/03 07:16:10	1.161
+++ class.c	1999/06/15 23:00:11
@@ -36,8 +36,6 @@ Boston, MA 02111-1307, USA.  */
 #define obstack_chunk_alloc xmalloc
 #define obstack_chunk_free free
 
-extern struct obstack permanent_obstack;
-
 /* This is how we tell when two virtual member functions are really the
    same.  */
 #define SAME_FN(FN1DECL, FN2DECL) (DECL_ASSEMBLER_NAME (FN1DECL) == DECL_ASSEMBLER_NAME (FN2DECL))
@@ -90,7 +88,7 @@ tree previous_class_values;	/* TREE_LIST
 static struct obstack class_cache_obstack;
 /* The first object allocated on that obstack.  We can use
    obstack_free with tis value to free the entire obstack.  */
-static char *class_cache_firstobj;
+char *class_cache_firstobj;
 
 struct base_info;
 
@@ -1136,7 +1134,8 @@ void
 add_method (type, fields, method)
      tree type, *fields, method;
 {
-  push_obstacks (&permanent_obstack, &permanent_obstack);
+  push_obstacks_nochange ();
+  end_temporary_allocation ();
 
   /* Setting the DECL_CONTEXT and DECL_CLASS_CONTEXT here is probably
      redundant.  */
@@ -4440,7 +4439,8 @@ pushclass (type, modify)
       invalidate_class_lookup_cache ();
 
       /* Now, free the obstack on which we cached all the values.  */
-      obstack_free (&class_cache_obstack, class_cache_firstobj);
+      if (class_cache_firstobj)
+	obstack_free (&class_cache_obstack, class_cache_firstobj);
       class_cache_firstobj 
 	= (char*) obstack_finish (&class_cache_obstack);
     }
@@ -5197,7 +5197,7 @@ print_class_statistics ()
    effect is undone by pop_obstacks.  */
 
 void
-maybe_push_cache_obstack ()
+push_cache_obstack ()
 {
   static int cache_obstack_initialized;
 
Index: decl.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/gcc/cp/decl.c,v
retrieving revision 1.371
diff -u -p -r1.371 decl.c
--- decl.c	1999/06/05 11:03:52	1.371
+++ decl.c	1999/06/15 23:00:23
@@ -63,8 +63,6 @@ extern tree global_namespace;
 extern void (*print_error_function) PROTO((char *));
 extern int (*valid_lang_attribute) PROTO ((tree, tree, tree, tree));
 
-/* Stack of places to restore the search obstack back to.  */
-   
 /* Obstack used for remembering local class declarations (like
    enums and static (const) members.  */
 #include "stack.h"
@@ -2466,6 +2464,7 @@ struct saved_scope {
   tree previous_class_type, previous_class_values;
   int processing_specialization;
   int processing_explicit_instantiation;
+  char *class_cache_firstobj;
 };
 static struct saved_scope *current_saved_scope;
 
@@ -2583,6 +2582,7 @@ maybe_push_to_top_level (pseudo)
   s->processing_template_decl = processing_template_decl;
   s->previous_class_type = previous_class_type;
   s->previous_class_values = previous_class_values;
+  s->class_cache_firstobj = class_cache_firstobj;
   s->processing_specialization = processing_specialization;
   s->processing_explicit_instantiation = processing_explicit_instantiation;
 
@@ -2598,6 +2598,7 @@ maybe_push_to_top_level (pseudo)
   shadowed_labels = NULL_TREE;
   minimal_parse_mode = 0;
   previous_class_type = previous_class_values = NULL_TREE;
+  class_cache_firstobj = 0;
   processing_specialization = 0;
   processing_explicit_instantiation = 0;
   current_template_parms = NULL_TREE;
@@ -2669,6 +2670,7 @@ pop_from_top_level ()
   previous_class_values = s->previous_class_values;
   processing_specialization = s->processing_specialization;
   processing_explicit_instantiation = s->processing_explicit_instantiation;
+  class_cache_firstobj = s->class_cache_firstobj;
 
   free (s);
 
@@ -4471,7 +4473,7 @@ push_class_level_binding (name, x)
      IDENTIFIER_CLASS_VALUE.  */
   if (push_class_binding (name, x))
     {
-      maybe_push_cache_obstack ();
+      push_cache_obstack ();
       class_binding_level->class_shadowed
 	= tree_cons (name, IDENTIFIER_CLASS_VALUE (name),
 		     class_binding_level->class_shadowed);
Index: search.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/gcc/cp/search.c,v
retrieving revision 1.106
diff -u -p -r1.106 search.c
--- search.c	1999/06/07 13:28:06	1.106
+++ search.c	1999/06/15 23:00:25
@@ -2982,7 +2982,7 @@ push_class_decls (type)
   /* Build up all the relevant bindings and such on the cache
      obstack.  That way no memory is wasted when we throw away the
      cache later.  */
-  maybe_push_cache_obstack ();
+  push_cache_obstack ();
 
   /* Enter type declarations and mark.  */
   dfs_walk (TYPE_BINFO (type), dfs_push_type_decls, unmarked_pushdecls_p, 0);
@@ -2990,7 +2990,7 @@ push_class_decls (type)
   /* Enter non-type declarations and unmark.  */
   dfs_walk (TYPE_BINFO (type), dfs_push_decls, marked_pushdecls_p, 0);
 
-  /* Undo the call to maybe_push_cache_obstack above.  */
+  /* Undo the call to push_cache_obstack above.  */
   pop_obstacks ();
 
   current_obstack = ambient_obstack;