http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45722
--- Comment #28 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2010-11-12
11:20:12 UTC ---
AFAICS Dave's analysis still holds. The problematic insn is
(insn 88 87 89 5 (set (reg:DI 134 [ x$l ])
(mem/c:DI (reg/f:SI 185) [0 MEM[(struct E *)&sE]+0 S8 A8]))
pr45722.c:50 -1
(nil))
(gdb) frame 1
#1 0x00000000007678ff in expand_assignment (to=0x7ffff7fbfcb8,
from=0x7ffff7107000, nontemporal=0 '\000')
at /home/eric/svn/gcc/gcc/expr.c:4474
4474 result = store_expr (from, to_rtx, 0, nontemporal);
(gdb) p debug_generic_expr(from)
MEM[(struct E *)&sE]
$9 = void
(gdb) p debug_generic_expr(to)
x$l_3
The we arrive in the MEM expander:
align = MAX (TYPE_ALIGN (TREE_TYPE (exp)),
get_object_alignment (exp, BIGGEST_ALIGNMENT));
op0 = expand_expr (base, NULL_RTX, VOIDmode, EXPAND_SUM);
op0 = convert_memory_address_addr_space (address_mode, op0, as);
if (!integer_zerop (TREE_OPERAND (exp, 1)))
{
rtx off
= immed_double_int_const (mem_ref_offset (exp), address_mode);
op0 = simplify_gen_binary (PLUS, address_mode, op0, off);
}
op0 = memory_address_addr_space (mode, op0, as);
temp = gen_rtx_MEM (mode, op0);
set_mem_attributes (temp, exp, 0);
set_mem_addr_space (temp, as);
(gdb) p align
$21 = 64
(gdb) p debug_rtx(temp)
(mem/c:DI (reg/f:SI 185) [0 MEM[(struct E *)&sE]+0 S8 A8])
so it's exactly the situation described in comment #16.
