[Bug lto/55736] lto ICE: tree code ''junl is not supported in LTO streams

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55736

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |lto
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-12-19
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> 2012-12-19 10:50:06 UTC ---
Confirmed.  We are writing

#3  0x0000000000bd2802 in write_ts_exp_tree_pointers (ob=0x20b4000, 
    expr=0x7ffff5d99ca0, ref_p=false)
    at /space/rguenther/src/svn/trunk/gcc/tree-streamer-out.c:747
747       stream_write_tree (ob, TREE_BLOCK (expr), ref_p);

of an ADDR_EXPR:

(gdb) call debug_tree (expr)
 <addr_expr 0x7ffff5d99ca0
    type <pointer_type 0x7ffff69380a8
        type <array_type 0x7ffff6938150 type <integer_type 0x7ffff6924930 char>
            BLK
            size <integer_cst 0x7ffff6917940 constant 88>
            unit size <integer_cst 0x7ffff6917960 constant 11>
            align 8 symtab 0 alias set -1 canonical type 0x7ffff69381f8 domain
<integer_type 0x7ffff69382a0>
            pointer_to_this <pointer_type 0x7ffff69380a8>>
        unsigned DI
        size <integer_cst 0x7ffff67e2d20 constant 64>
        unit size <integer_cst 0x7ffff67e2d40 constant 8>
        align 64 symtab 0 alias set -1 canonical type 0x7ffff69380a8>
    readonly constant
    arg 0 <string_cst 0x7ffff5d99cc0 type <array_type 0x7ffff6938150>
        readonly constant static "<lightred>\000">>

but it seems to have been collected.

The ADDR_EXPR is inside a CONSTRUCTOR which is created by switch-conversion:

 <var_decl 0x7ffff316fab0 CSWTCH.1083
    type <array_type 0x7ffff1112d20
        type <pointer_type 0x7ffff65a5150 type <array_type 0x7ffff65a51f8>
            unsigned DI
            size <integer_cst 0x7ffff67e2d20 constant 64>
            unit size <integer_cst 0x7ffff67e2d40 constant 8>
            align 64 symtab 0 alias set -1 canonical type 0x7ffff69380a8>
        BLK
        size <integer_cst 0x7ffff6917900 constant 448>
        unit size <integer_cst 0x7ffff6917b20 constant 56>
        align 64 symtab 0 alias set -1 canonical type 0x7ffff1112d20
        domain <integer_type 0x7ffff693e150 type <integer_type 0x7ffff67f3000
sizetype>
            DI size <integer_cst 0x7ffff67e2d20 64> unit size <integer_cst
0x7ffff67e2d40 8>
            align 64 symtab 0 alias set -1 canonical type 0x7ffff67f3738
precision 64 min <integer_cst 0x7ffff67e2d60 0> max <integer_cst 0x7ffff6917b40
6>>
        pointer_to_this <pointer_type 0x7ffff0e8a150>>
    readonly constant static BLK file output.cc line 1198 col 0 size
<integer_cst 0x7ffff6917900 448> unit size <integer_cst 0x7ffff6917b20 56>
    align 256 initial <constructor 0x7ffff104f360>>

DECL_INITIAL is written via

322       /* Write any LTO-specific data to OB.  */
323       if (DECL_P (expr)
324           && TREE_CODE (expr) != FUNCTION_DECL
325           && TREE_CODE (expr) != TRANSLATION_UNIT_DECL)
326         {
327           /* Handle DECL_INITIAL for symbols.  */
328           tree initial = DECL_INITIAL (expr);
329           if (TREE_CODE (expr) == VAR_DECL
(gdb) l
330               && (TREE_STATIC (expr) || DECL_EXTERNAL (expr))
331               && !DECL_IN_CONSTANT_POOL (expr)
332               && initial)
333             {
334               lto_symtab_encoder_t encoder;
335               struct varpool_node *vnode;
336
337               encoder = ob->decl_state->symtab_node_encoder;
338               vnode = varpool_get_node (expr);
339               if (!vnode
...

so we seem to have an issue with BLOCKs being referenced from DECL_INITIALs
of decls we put into varpool.  The case in question (switch-conversion)
may be the only way this happens, but who knows what frontends do here?

Btw, switch-conversion forgets to unshare the exprs as well.