[Bug c/53424] dynamic array expressions get wrong sizeof() if pointers to const are involved and the pointers are changed (const is misapplied to the whole expression)

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53424

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-05-26 
23:47:56 UTC ---
(gdb) p debug_tree(t)
 <indirect_ref 0x7ffff6e4c500
    type <integer_type 0x7ffff6e6e000 int readonly SI
        size <integer_cst 0x7ffff6d4d080 constant 32>
        unit size <integer_cst 0x7ffff6d4d0a0 constant 4>
        align 32 symtab 0 alias set -1 canonical type 0x7ffff6e6e000 precision
32 min <integer_cst 0x7ffff6d4d020 -2147483648> max <integer_cst 0x7ffff6d4d040
2147483647>
        pointer_to_this <pointer_type 0x7ffff6e6e0a8>>
    readonly
    arg 0 <var_decl 0x7ffff6d3e280 x
        type <pointer_type 0x7ffff6e6e0a8 type <integer_type 0x7ffff6e6e000
int>
            unsigned DI
            size <integer_cst 0x7ffff6d31d40 constant 64>
            unit size <integer_cst 0x7ffff6d31d60 constant 8>
            align 64 symtab 0 alias set -1 canonical type 0x7ffff6e6e0a8>
        used unsigned DI file t1.c line 6 col 13 size <integer_cst
0x7ffff6d31d40 64> unit size <integer_cst 0x7ffff6d31d60 8>
        align 64 context <function_decl 0x7ffff6e52200 broken> initial
<nop_expr 0x7ffff6e4c4b0>>
    t1.c:7:11>

The indirect reference is marked as readonly.
2663    static bool
2664    tree_invariant_p_1 (tree t)
2665    {
2666      tree op;
2667    
2668      if (TREE_CONSTANT (t)
2669          || (TREE_READONLY (t) && !TREE_SIDE_EFFECTS (t)))
2670        return true;

Is where the issue is.