On 16 Apr 2014, at 17:36, Richard Henderson <r...@redhat.com> wrote:
> On 04/16/2014 12:39 AM, Eric Botcazou wrote: >>> The primary bit of rfc here is the hunk that applies to ada/types.h >>> with respect to Fat_Pointer. Given that the Ada type, as defined in >>> s-stratt.ads, does not include alignment, I can't imagine why the C >>> type should have it. >> >> See gcc-interface/utils.c:finish_fat_pointer_type. > > Ah hah. > > /* Make sure we can put it into a register. */ > if (STRICT_ALIGNMENT) > TYPE_ALIGN (record_type) = MIN (BIGGEST_ALIGNMENT, 2 * POINTER_SIZE); > > AArch64 is not a STRICT_ALIGNMENT target, thus the mismatch. As the align attribute in types.h is for the host, couldn't a configure test solve this issue ? > If we were to make this alignment unconditional, would it be better to drop > the > code from here in finish_fat_pointer_type and instead record that in the Ada > source, as we do with the C source? > > I presume > > for Fat_Pointer'Alignment use System.Address'Size * 2; > > or some such incantation would do that... One of the most common Fat_Pointer is for strings, which aren't declared in any source and is very commonly used. OTOH, I think this optimization mostly targets sparc. Tristan.
