This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
C++ PATCH to anonymous union handling
- From: Jason Merrill <jason at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Thu, 19 Dec 2002 12:14:47 -0500
- Subject: C++ PATCH to anonymous union handling
This patch implements something I've been meaning to do for a while: we now
deal with anonymous unions by declaring the names to be COMPONENT_REFs
rather than by playing games with RTL. This also changes the mangling of
static duration anonymous unions to be based on the name of the first named
field in a depthwise search; this has no binary compatibility impact,
however, since affected code was previously broken. An example is
g++.brendan/union1.C, which is fixed by this patch.
2002-12-18 Jason Merrill <jason@redhat.com>
Handle anonymous unions at the tree level.
C++ ABI change: Mangle anonymous unions using the name of their
first named field (by depth-first search). Should not cause
binary compatibility problems, though, as the compiler previously
didn't emit anything for affected unions.
* cp-tree.def (ALIAS_DECL): New tree code.
* decl2.c (build_anon_union_vars): Build ALIAS_DECLs. Return the
first field, not the largest.
(finish_anon_union): Don't mess with RTL. Do set DECL_ASSEMBLER_NAME,
push the decl, and write it out at namespace scope.
* decl.c (lookup_name_real): See through an ALIAS_DECL.
(pushdecl): Add namespace bindings for ALIAS_DECLs.
* rtti.c (unemitted_tinfo_decl_p): Don't try to look at the name
of a decl which doesn't have one.
* typeck.c (build_class_member_access_expr): Don't recurse if
we already have the type we want.
*** cp-tree.def.~1~ 2002-10-06 15:46:36.000000000 -0400
--- cp-tree.def 2002-12-18 17:07:15.000000000 -0500
*************** DEFTREECODE (THROW_EXPR, "throw_expr", '
*** 89,94 ****
--- 89,98 ----
these to avoid actually creating instances of the empty classes. */
DEFTREECODE (EMPTY_CLASS_EXPR, "empty_class_expr", 'e', 0)
+ /* A DECL which is really just a placeholder for an expression. Used to
+ implement non-class scope anonymous unions. */
+ DEFTREECODE (ALIAS_DECL, "alias_decl", 'd', 0)
+
/* A reference to a member function or member functions from a base
class. BASELINK_FUNCTIONS gives the FUNCTION_DECL,
TEMPLATE_DECL, OVERLOAD, or TEMPLATE_ID_EXPR corresponding to the
*** decl2.c.~1~ 2002-12-16 15:30:26.000000000 -0500
--- decl2.c 2002-12-18 19:07:22.000000000 -0500
*************** static int maybe_emit_vtables (tree);
*** 66,72 ****
static int is_namespace_ancestor PARAMS ((tree, tree));
static void add_using_namespace PARAMS ((tree, tree, int));
static tree ambiguous_decl PARAMS ((tree, tree, tree,int));
! static tree build_anon_union_vars PARAMS ((tree, tree*, int, int));
static int acceptable_java_type PARAMS ((tree));
static void output_vtable_inherit PARAMS ((tree));
static tree start_objects PARAMS ((int, int));
--- 66,72 ----
static int is_namespace_ancestor PARAMS ((tree, tree));
static void add_using_namespace PARAMS ((tree, tree, int));
static tree ambiguous_decl PARAMS ((tree, tree, tree,int));
! static tree build_anon_union_vars PARAMS ((tree));
static int acceptable_java_type PARAMS ((tree));
static void output_vtable_inherit PARAMS ((tree));
static tree start_objects PARAMS ((int, int));
*************** defer_fn (fn)
*** 1269,1290 ****
VARRAY_PUSH_TREE (deferred_fns, fn);
}
! /* Hunts through the global anonymous union ANON_DECL, building
! appropriate VAR_DECLs. Stores cleanups on the list of ELEMS, and
! returns a VAR_DECL whose size is the same as the size of the
! ANON_DECL, if one is available.
!
! FIXME: we should really handle anonymous unions by binding the names
! of the members to COMPONENT_REFs rather than this kludge. */
!
! static tree
! build_anon_union_vars (anon_decl, elems, static_p, external_p)
! tree anon_decl;
! tree* elems;
! int static_p;
! int external_p;
{
! tree type = TREE_TYPE (anon_decl);
tree main_decl = NULL_TREE;
tree field;
--- 1269,1283 ----
VARRAY_PUSH_TREE (deferred_fns, fn);
}
! /* Walks through the namespace- or function-scope anonymous union OBJECT,
! building appropriate ALIAS_DECLs. Returns one of the fields for use in
! the mangled name. */
!
! static tree
! build_anon_union_vars (object)
! tree object;
{
! tree type = TREE_TYPE (object);
tree main_decl = NULL_TREE;
tree field;
*************** build_anon_union_vars (anon_decl, elems,
*** 1298,1309 ****
field = TREE_CHAIN (field))
{
tree decl;
if (DECL_ARTIFICIAL (field))
continue;
if (TREE_CODE (field) != FIELD_DECL)
{
! cp_pedwarn_at ("`%#D' invalid; an anonymous union can only have non-static data members",
field);
continue;
}
--- 1291,1304 ----
field = TREE_CHAIN (field))
{
tree decl;
+ tree ref;
if (DECL_ARTIFICIAL (field))
continue;
if (TREE_CODE (field) != FIELD_DECL)
{
! cp_pedwarn_at ("\
! `%#D' invalid; an anonymous union can only have non-static data members",
field);
continue;
}
*************** build_anon_union_vars (anon_decl, elems,
*** 1313,1367 ****
else if (TREE_PROTECTED (field))
cp_pedwarn_at ("protected member `%#D' in anonymous union", field);
! if (DECL_NAME (field) == NULL_TREE
! && ANON_AGGR_TYPE_P (TREE_TYPE (field)))
! {
! decl = build_anon_union_vars (field, elems, static_p, external_p);
! if (!decl)
! continue;
! }
! else if (DECL_NAME (field) == NULL_TREE)
! continue;
! else
{
! decl = build_decl (VAR_DECL, DECL_NAME (field), TREE_TYPE (field));
! /* tell `pushdecl' that this is not tentative. */
! DECL_INITIAL (decl) = error_mark_node;
TREE_PUBLIC (decl) = 0;
! TREE_STATIC (decl) = static_p;
! DECL_EXTERNAL (decl) = external_p;
decl = pushdecl (decl);
- DECL_INITIAL (decl) = NULL_TREE;
}
! /* Only write out one anon union element--choose the largest
! one. We used to try to find one the same size as the union,
! but that fails if the ABI forces us to align the union more
! strictly. */
! if (main_decl == NULL_TREE
! || tree_int_cst_lt (DECL_SIZE (main_decl), DECL_SIZE (decl)))
! {
! if (main_decl)
! TREE_ASM_WRITTEN (main_decl) = 1;
! main_decl = decl;
! }
! else
! /* ??? This causes there to be no debug info written out
! about this decl. */
! TREE_ASM_WRITTEN (decl) = 1;
!
! if (DECL_NAME (field) == NULL_TREE
! && ANON_AGGR_TYPE_P (TREE_TYPE (field)))
! /* The remainder of the processing was already done in the
! recursive call. */
! continue;
!
! /* If there's a cleanup to do, it belongs in the
! TREE_PURPOSE of the following TREE_LIST. */
! *elems = tree_cons (NULL_TREE, decl, *elems);
! TREE_TYPE (*elems) = type;
}
!
return main_decl;
}
--- 1308,1332 ----
else if (TREE_PROTECTED (field))
cp_pedwarn_at ("protected member `%#D' in anonymous union", field);
! ref = build_class_member_access_expr (object, field, NULL_TREE,
! false);
!
! if (DECL_NAME (field))
{
! decl = build_decl (ALIAS_DECL, DECL_NAME (field), TREE_TYPE (field));
! DECL_INITIAL (decl) = ref;
TREE_PUBLIC (decl) = 0;
! TREE_STATIC (decl) = 0;
! DECL_EXTERNAL (decl) = 1;
decl = pushdecl (decl);
}
+ else if (ANON_AGGR_TYPE_P (TREE_TYPE (field)))
+ decl = build_anon_union_vars (ref);
! if (main_decl == NULL_TREE)
! main_decl = decl;
}
!
return main_decl;
}
*************** finish_anon_union (anon_union_decl)
*** 1376,1383 ****
tree type = TREE_TYPE (anon_union_decl);
tree main_decl;
int public_p = TREE_PUBLIC (anon_union_decl);
- int static_p = TREE_STATIC (anon_union_decl);
- int external_p = DECL_EXTERNAL (anon_union_decl);
/* The VAR_DECL's context is the same as the TYPE's context. */
DECL_CONTEXT (anon_union_decl) = DECL_CONTEXT (TYPE_NAME (type));
--- 1341,1346 ----
*************** finish_anon_union (anon_union_decl)
*** 1393,1421 ****
if (!processing_template_decl)
{
! main_decl
! = build_anon_union_vars (anon_union_decl,
! &DECL_ANON_UNION_ELEMS (anon_union_decl),
! static_p, external_p);
!
if (main_decl == NULL_TREE)
{
! warning ("anonymous aggregate with no members");
return;
}
! if (static_p)
! {
! make_decl_rtl (main_decl, 0);
! COPY_DECL_RTL (main_decl, anon_union_decl);
! expand_anon_union_decl (anon_union_decl,
! NULL_TREE,
! DECL_ANON_UNION_ELEMS (anon_union_decl));
! return;
! }
}
! add_decl_stmt (anon_union_decl);
}
/* Auxiliary functions to make type signatures for
--- 1356,1382 ----
if (!processing_template_decl)
{
! main_decl = build_anon_union_vars (anon_union_decl);
!
if (main_decl == NULL_TREE)
{
! warning ("anonymous union with no members");
return;
}
! /* Use main_decl to set the mangled name. */
! DECL_NAME (anon_union_decl) = DECL_NAME (main_decl);
! mangle_decl (anon_union_decl);
! DECL_NAME (anon_union_decl) = NULL_TREE;
}
! pushdecl (anon_union_decl);
! if (building_stmt_tree ()
! && at_function_scope_p ())
! add_decl_stmt (anon_union_decl);
! else if (!processing_template_decl)
! rest_of_decl_compilation (anon_union_decl, NULL,
! toplevel_bindings_p (), at_eof);
}
/* Auxiliary functions to make type signatures for
*** decl.c.~1~ 2002-12-18 11:20:29.000000000 -0500
--- decl.c 2002-12-18 17:11:16.000000000 -0500
*************** pushdecl (x)
*** 4051,4056 ****
--- 4051,4057 ----
&& t != NULL_TREE)
&& (TREE_CODE (x) == TYPE_DECL
|| TREE_CODE (x) == VAR_DECL
+ || TREE_CODE (x) == ALIAS_DECL
|| TREE_CODE (x) == NAMESPACE_DECL
|| TREE_CODE (x) == CONST_DECL
|| TREE_CODE (x) == TEMPLATE_DECL))
*************** does not match lookup in the current sco
*** 6228,6233 ****
--- 6229,6237 ----
else if (from_obj)
val = from_obj;
+ if (val && TREE_CODE (val) == ALIAS_DECL)
+ val = DECL_INITIAL (val);
+
return val;
}
*** rtti.c.~1~ 2002-12-16 15:30:30.000000000 -0500
--- rtti.c 2002-12-19 10:42:30.000000000 -0500
*************** unemitted_tinfo_decl_p (t, data)
*** 1444,1450 ****
{
if (/* It's a var decl */
TREE_CODE (t) == VAR_DECL
! /* whos name points back to itself */
&& IDENTIFIER_GLOBAL_VALUE (DECL_NAME (t)) == t
/* whose name's type is non-null */
&& TREE_TYPE (DECL_NAME (t))
--- 1444,1452 ----
{
if (/* It's a var decl */
TREE_CODE (t) == VAR_DECL
! /* which has a name */
! && DECL_NAME (t)
! /* whose name points back to itself */
&& IDENTIFIER_GLOBAL_VALUE (DECL_NAME (t)) == t
/* whose name's type is non-null */
&& TREE_TYPE (DECL_NAME (t))
*** typeck.c.~1~ 2002-12-18 11:20:30.000000000 -0500
--- typeck.c 2002-12-19 10:53:31.000000000 -0500
*************** build_class_member_access_expr (tree obj
*** 1987,1993 ****
OBJECT so that it refers to the class containing the
anonymous union. Generate a reference to the anonymous union
itself, and recur to find MEMBER. */
! if (ANON_AGGR_TYPE_P (DECL_CONTEXT (member)))
{
tree anonymous_union;
--- 1987,1994 ----
OBJECT so that it refers to the class containing the
anonymous union. Generate a reference to the anonymous union
itself, and recur to find MEMBER. */
! if (ANON_AGGR_TYPE_P (DECL_CONTEXT (member))
! && !same_type_p (object_type, DECL_CONTEXT (member)))
{
tree anonymous_union;