re PR middle-end/27793 (num_ssa_names inconsistent or immediate use iterator wrong)

	PR middle-end/27793
	* cp-tree.h (cxx_int_tree_map): New struct.
	(struct language_function): Add extern_decl_map field.
	* name-lookup.c (pushdecl_maybe_friend): Add x -> t mapping
	to cp_function_chain->extern_decl_map hash table instead of
	copying over DECL_UID.
	* cp-gimplify.c (cxx_int_tree_map_eq, cxx_int_tree_map_hash): New
	functions.
	(cp_genericize_r): Remap DECL_EXTERN local decls using
	cp_function_chain->extern_decl_map hash table.
	* decl.c (finish_function): Clear extern_decl_map.

	PR c++/26757
	PR c++/27894
	* g++.dg/tree-ssa/pr26757.C: New test.
	* g++.dg/tree-ssa/pr27894.C: New test.

From-SVN: r114607

gcc/cp/ChangeLog

+2006-06-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/27793
+	* cp-tree.h (cxx_int_tree_map): New struct.
+	(struct language_function): Add extern_decl_map field.
+	* name-lookup.c (pushdecl_maybe_friend): Add x -> t mapping
+	to cp_function_chain->extern_decl_map hash table instead of
+	copying over DECL_UID.
+	* cp-gimplify.c (cxx_int_tree_map_eq, cxx_int_tree_map_hash): New
+	functions.
+	(cp_genericize_r): Remap DECL_EXTERN local decls using
+	cp_function_chain->extern_decl_map hash table.
+	* decl.c (finish_function): Clear extern_decl_map.
+
 2006-06-12  Volker Reichelt  <reichelt@igpm.rwth-aachen.de>
 
 	PR c++/27601

gcc/cp/cp-gimplify.c

@@ -601,6 +601,24 @@ is_invisiref_parm (tree t)
 	  && DECL_BY_REFERENCE (t));
 }
 
+/* Return true if the uid in both int tree maps are equal.  */
+
+int
+cxx_int_tree_map_eq (const void *va, const void *vb)
+{
+  const struct cxx_int_tree_map *a = (const struct cxx_int_tree_map *) va;
+  const struct cxx_int_tree_map *b = (const struct cxx_int_tree_map *) vb;
+  return (a->uid == b->uid);
+}
+
+/* Hash a UID in a cxx_int_tree_map.  */
+
+unsigned int
+cxx_int_tree_map_hash (const void *item)
+{
+  return ((const struct cxx_int_tree_map *)item)->uid;
+}
+
 /* Perform any pre-gimplification lowering of C++ front end trees to
    GENERIC.  */
 
@@ -620,6 +638,25 @@ cp_genericize_r (tree *stmt_p, int *walk_subtrees, void *data)
       return NULL;
     }
 
+  /* Map block scope extern declarations to visible declarations with the
+     same name and type in outer scopes if any.  */
+  if (cp_function_chain->extern_decl_map
+      && (TREE_CODE (stmt) == FUNCTION_DECL || TREE_CODE (stmt) == VAR_DECL)
+      && DECL_EXTERNAL (stmt))
+    {
+      struct cxx_int_tree_map *h, in;
+      in.uid = DECL_UID (stmt);
+      h = (struct cxx_int_tree_map *)
+	  htab_find_with_hash (cp_function_chain->extern_decl_map,
+			       &in, in.uid);
+      if (h)
+	{
+	  *stmt_p = h->to;
+	  *walk_subtrees = 0;
+	  return NULL;
+	}
+    }
+
   /* Other than invisiref parms, don't walk the same tree twice.  */
   if (pointer_set_contains (p_set, stmt))
     {

gcc/cp/cp-tree.h

@@ -721,6 +721,15 @@ struct saved_scope GTY(())
 
 extern GTY(()) struct saved_scope *scope_chain;
 
+struct cxx_int_tree_map GTY(())
+{
+  unsigned int uid;
+  tree to;
+};
+
+extern unsigned int cxx_int_tree_map_hash (const void *);
+extern int cxx_int_tree_map_eq (const void *, const void *);
+
 /* Global state pertinent to the current function.  */
 
 struct language_function GTY(())
@@ -747,6 +756,7 @@ struct language_function GTY(())
   htab_t GTY((param_is(struct named_label_entry))) x_named_labels;
   struct cp_binding_level *bindings;
   VEC(tree,gc) *x_local_names;
+  htab_t GTY((param_is (struct cxx_int_tree_map))) extern_decl_map;
 };
 
 /* The current C++-specific per-function global variables.  */

gcc/cp/decl.c

@@ -11102,6 +11102,7 @@ finish_function (int flags)
       f->x_vtt_parm = NULL;
       f->x_return_value = NULL;
       f->bindings = NULL;
+      f->extern_decl_map = NULL;
 
       /* Handle attribute((warn_unused_result)).  Relies on gimple input.  */
       c_warn_unused_result (&DECL_SAVED_TREE (fndecl));

gcc/cp/name-lookup.c

@@ -670,14 +670,28 @@ pushdecl_maybe_friend (tree x, bool is_friend)
 	      if (decls_match (x, t))
 		/* The standard only says that the local extern
 		   inherits linkage from the previous decl; in
-		   particular, default args are not shared.  We must
-		   also tell cgraph to treat these decls as the same,
-		   or we may neglect to emit an "unused" static - we
-		   do this by making the DECL_UIDs equal, which should
-		   be viewed as a kludge.  FIXME.  */
+		   particular, default args are not shared.  Add
+		   the decl into a hash table to make sure only
+		   the previous decl in this case is seen by the
+		   middle end.  */
 		{
+		  struct cxx_int_tree_map *h;
+		  void **loc;
+
 		  TREE_PUBLIC (x) = TREE_PUBLIC (t);
-		  DECL_UID (x) = DECL_UID (t);
+
+		  if (cp_function_chain->extern_decl_map == NULL)
+		    cp_function_chain->extern_decl_map
+		      = htab_create_ggc (20, cxx_int_tree_map_hash,
+					 cxx_int_tree_map_eq, NULL);
+
+		  h = GGC_NEW (struct cxx_int_tree_map);
+		  h->uid = DECL_UID (x);
+		  h->to = t;
+		  loc = htab_find_slot_with_hash
+			  (cp_function_chain->extern_decl_map, h,
+			   h->uid, INSERT);
+		  *(struct cxx_int_tree_map **) loc = h;
 		}
 	    }
 	  else if (TREE_CODE (t) == PARM_DECL)

gcc/testsuite/ChangeLog

+2006-06-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/27894
+	* g++.dg/tree-ssa/pr26757.C: New test.
+	* g++.dg/tree-ssa/pr27894.C: New test.
+
 2006-06-13  Maxim Kuvyrkov  <mkuvyrkov@ispras.ru>
 
 	* gcc.c-torture/compile/20060609-1.c: New test.

gcc/testsuite/g++.dg/tree-ssa/pr26757.C

+// PR c++/26757
+// { dg-do run }
+// { dg-options "-O" }
+
+extern "C" void abort ();
+
+typedef struct A
+{
+  int c;
+  int d;
+} A;
+
+A *b;
+
+void
+foo ()
+{
+  b->c++;
+  extern A *b;
+  b->d++;
+
+}
+
+void
+bar ()
+{
+  if (b->d)
+    b->c++;
+}
+
+
+int
+main ()
+{
+  A a = { 0, 0 };
+  b = &a;
+  foo ();
+  bar ();
+  if (b->c != 2)
+    abort ();
+  if (b->d != 1)
+    abort ();
+  return 0;
+}

gcc/testsuite/g++.dg/tree-ssa/pr27894.C

+// PR c++/27894
+// { dg-do compile }
+// { dg-options "-O" }
+
+class A;
+struct B
+{
+  B (unsigned long);
+  int b2 () const;
+  A *b1 () const;
+};
+
+enum { P = 0 };
+enum O { Q = 75, };
+class C;
+struct D { A *d; };
+struct E
+{
+  B e1 (int) const;
+  A *e2 (const B &) const;
+  D e3[4096];
+};
+
+inline A *
+E::e2 (const B & x) const
+{
+  const D *w = &e3[x.b2 ()];
+  return (A *) w->d;
+}
+
+extern E *e;
+
+inline A *
+B::b1 () const
+{
+  extern E *e;
+  return e->e2 (*this);
+}
+
+template <class T> struct F : public B
+{
+  F (const B &);
+  T *b1 () const;
+};
+
+template < class T > inline T * F <T>::b1 () const
+{
+  return (T *) B::b1 ();
+};
+
+typedef F <C> N;
+
+class G {};
+class H : public G {};
+class I : public H {};
+class J {};
+class K {};
+struct L
+{
+  void l (J *, C *, int, const char *, O);
+};
+class M : public K, public I
+{
+  void m (J &, int, const char *);
+  void m (J &, int, int, const char *, float);
+};
+
+void
+M::m (J &x, int y, const char *z)
+{
+  L *w = new L;
+  N v = e->e1 (y);
+  w->l (&x, v.b1 (), P, z, Q);
+}
+
+void
+M::m (J &x, int y, int s, const char *z, float t)
+{
+  L *w = new L;
+  N v = e->e1 (y);
+  w->l (&x, v.b1 (), s, z, (O) (int) ((t) ? (50 + 20 / (float) t) : 0));
+}