Hi,
I noticed this while working on early-merging LTO. The DECL_VINDEX slot
of FUNCTION_DECLs is supposed to hold the numeric index of the vtable
slot if it's a virtual function. During parsing the C++ frontend uses it
to hold a reference to itself, which then later is supposed to be
transformed into the real index. Sometimes the C++ frontend copies
function_decls, leaving the old one reachable via various means (but not
as a reachable function, merely in scopes and the like), but fixes up
only the copy.
Instead of diddling with the frontend we can just as well zero out
meaningless DECL_VINDEX slots (i.e. when they're not an integer). It's
used for debug info generation (when it's an integer) and as a flag ala
"this function is a virtual method" by the middle-end.
Regstrapped on x86_64-linux with the other three cleanups. Okay for
trunk?
Ciao,
Michael.
--
* tree.c (free_lang_data_in_decl): Zero DECL_VINDEX if it's not
an integer.
* tree.h (tree_decl_non_common.vindex): Adjust comment.
Index: tree.c
===
--- tree.c (revision 171537)
+++ tree.c (working copy)
@@ -4647,6 +4647,13 @@ free_lang_data_in_decl (tree decl)
&& RECORD_OR_UNION_TYPE_P
(DECL_CONTEXT (DECL_ABSTRACT_ORIGIN (decl
DECL_ABSTRACT_ORIGIN (decl) = NULL_TREE;
+
+ /* Sometimes the C++ frontend doesn't manage to transform a temporary
+ DECL_VINDEX referring to itself into a vtable slot number as it
+should. Happens with functions that are copied and then forgotten
+about. Just clear it, it won't matter anymore. */
+ if (DECL_VINDEX (decl) && !host_integerp (DECL_VINDEX (decl), 0))
+ DECL_VINDEX (decl) = NULL_TREE;
}
else if (TREE_CODE (decl) == VAR_DECL)
{
Index: tree.h
===
--- tree.h (revision 171537)
+++ tree.h (working copy)
@@ -3228,7 +3233,7 @@ struct GTY(())
tree arguments;
/* Almost all FE's use this. */
tree result;
- /* C++ uses this in namespaces. */
+ /* C++ uses this in namespaces and function_decls. */
tree vindex;
};
