https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92925
--- Comment #2 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> We're supposed to use get_object_alignment to set MEM_ALIGN and we do in most
> of the cases (IIRC). So this must be an omission somewhere. So we indeed
> compute that but then we called set_mem_attributes_minus_bitpos with
> bptr_5(D)->a[i_11] but bitpos 64 - this seems to be a disconnect between
> the callers using get_inner_reference to decompose a ref but then still
> passing down the full ref tree to set_mem_attributes_minus_bitpos.
>
> (gdb) up
> #1 0x0000000000c969cf in expand_assignment (to=<array_ref 0x7ffff68180a8>,
> from=<constructor 0x7ffff6960108>, nontemporal=false)
> at /tmp/trunk2/gcc/expr.c:5357
> 5357 set_mem_attributes_minus_bitpos (to_rtx, to, 0,
> bitpos);
That's the point of set_mem_attributes_minus_bitpos: you use the full tree to
get the information. If we pass 'ref' instead of 'to', a good chunk of the
logic in there is disabled, e.g.:
/* If this is a field reference, record it. */
else if (TREE_CODE (t) == COMPONENT_REF)
{
attrs.expr = t;
attrs.offset_known_p = true;
attrs.offset = 0;
apply_bitpos = bitpos;
if (DECL_BIT_FIELD (TREE_OPERAND (t, 1)))
new_size = DECL_SIZE_UNIT (TREE_OPERAND (t, 1));
}
so I'm not sure what the issue could be. Let me have a closer look.
