On Sun, Jul 10, 2011 at 2:44 PM, Richard Henderson <r...@redhat.com> wrote:
> On 07/10/2011 12:43 PM, H.J. Lu wrote:
>> +/* Pointer function arguments and return values are promoted to Pmode.
>> + If FOR_RETURN is 1, this function must behave in the same way with
>> + regard to function returns as TARGET_FUNCTION_VALUE. */
>> +
>> +static enum machine_mode
>> +ix86_promote_function_mode (const_tree type, enum machine_mode mode,
>> + int *punsignedp, const_tree fntype,
>> + int for_return)
>> +{
>> + if (for_return == 1)
>> + /* Do not promote function return values. */
>> + ;
>> + else if (type != NULL_TREE && POINTER_TYPE_P (type))
>
> These two comments still conflict. And why wouldn't you want to
> promote return values?
We only want to promote function parameters passed/returned in register.
But I can't tell if a value will be passed in register or memory inside of
TARGET_FUNCTION_VALUE. So when FOR_RETURN is 1, we don't
promote. Even if we don't promote it explicitly, hardware still zero-extends
it for us. So it isn't a real issue.
--
H.J.
