http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54632
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2012-09-24
AssignedTo|unassigned at gcc dot |rguenth at gcc dot gnu.org
|gnu.org |
Ever Confirmed|0 |1
--- Comment #12 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-09-24
12:42:27 UTC ---
The backtrace hints at trees containing DECL_VALUE/DEBUG_EXPRs. We
are indeed writing TREE_BLOCK which has been garbage-collected.
(gdb) up
#3 0x0000000000dcf803 in write_ts_exp_tree_pointers (ob=0x1c809d0,
expr=0x7ffff4de0000, ref_p=true)
at /space/rguenther/src/svn/trunk/gcc/tree-streamer-out.c:674
674 stream_write_tree (ob, TREE_BLOCK (expr), ref_p);
...
#7 0x0000000000dcea3c in write_ts_decl_common_tree_pointers (ob=0x1c809d0,
expr=0x7ffff4ddc2f8, ref_p=true)
at /space/rguenther/src/svn/trunk/gcc/tree-streamer-out.c:509
509 stream_write_tree (ob, DECL_DEBUG_EXPR (expr), ref_p);
...
#11 0x0000000000ad8e10 in output_struct_function_base (ob=0x1c809d0,
fn=0x7ffff5440c80)
at /space/rguenther/src/svn/trunk/gcc/lto-streamer-out.c:751
748 /* Output all the local variables in the function. */
749 streamer_write_hwi (ob, VEC_length (tree, fn->local_decls));
750 FOR_EACH_VEC_ELT (tree, fn->local_decls, i, t)
751 stream_write_tree (ob, t, true);
so somehow GC does not mark this block as used (or it is not marked
as used in the block tree and thus removed in remove_unused_scope_block_p).
We indeed forget to walk all locals in clear_unused_block_pointer ().
Testing
Index: gcc/tree-ssa-live.c
===================================================================
--- gcc/tree-ssa-live.c (revision 191664)
+++ gcc/tree-ssa-live.c (working copy)
@@ -620,11 +620,6 @@ clear_unused_block_pointer_1 (tree *tp,
if (EXPR_P (*tp) && TREE_BLOCK (*tp)
&& !TREE_USED (TREE_BLOCK (*tp)))
TREE_SET_BLOCK (*tp, NULL);
- if (TREE_CODE (*tp) == VAR_DECL && DECL_DEBUG_EXPR_IS_FROM (*tp))
- {
- tree debug_expr = DECL_DEBUG_EXPR (*tp);
- walk_tree (&debug_expr, clear_unused_block_pointer_1, NULL, NULL);
- }
return NULL_TREE;
}
@@ -636,6 +631,16 @@ clear_unused_block_pointer ()
{
basic_block bb;
gimple_stmt_iterator gsi;
+ tree t;
+ unsigned i;
+
+ FOR_EACH_VEC_ELT (tree, cfun->local_decls, i, t)
+ if (TREE_CODE (t) == VAR_DECL && DECL_DEBUG_EXPR_IS_FROM (t))
+ {
+ tree debug_expr = DECL_DEBUG_EXPR (t);
+ walk_tree (&debug_expr, clear_unused_block_pointer_1, NULL, NULL);
+ }
+
FOR_EACH_BB (bb)
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
