On Fri, Mar 1, 2013 at 3:56 PM, Eric Botcazou <ebotca...@adacore.com> wrote:
>> But in theory this pessimizes code as aggregate_value_p returned true
>> for this? That is, isn't the bug that we rewrite a possible
>> return-slot-decl into SSA? (do we do that here?)
>
> Yes, aggregate_value_p returns true for this because the ABI says that this
> type is returned in memory. And, no, I don't think that this will further
> pessimize, given that it's already "pessimized" in gimplify_modify_expr_rhs:
>
> case CALL_EXPR:
> /* For calls that return in memory, give *to_p as the CALL_EXPR's
> return slot so that we don't generate a temporary. */
> if (!CALL_EXPR_RETURN_SLOT_OPT (*from_p)
> && aggregate_value_p (*from_p, *from_p))
> {
> bool use_target;
>
> if (!(rhs_predicate_for (*to_p))(*from_p))
> /* If we need a temporary, *to_p isn't accurate. */
> use_target = false;
> /* It's OK to use the return slot directly unless it's an NRV.
> */
> else if (TREE_CODE (*to_p) == RESULT_DECL
> && DECL_NAME (*to_p) == NULL_TREE
> && needs_to_live_in_memory (*to_p))
> use_target = true;
> else if (is_gimple_reg_type (TREE_TYPE (*to_p))
> || (DECL_P (*to_p) && DECL_REGISTER (*to_p)))
> /* Don't force regs into memory. */
> use_target = false;
Ah, ok. Patch is ok then.
Thanks,
Richard.
> --
> Eric Botcazou
