http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52395
--- Comment #9 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-02-27
14:51:27 UTC ---
(In reply to comment #6)
> If all was well ('base' is literally appearing in the IL before SRA / IPA-SRA)
> we could do
>
> Index: gcc/tree-sra.c
> ===================================================================
> --- gcc/tree-sra.c (revision 184591)
> +++ gcc/tree-sra.c (working copy)
> @@ -1526,10 +1526,12 @@ build_ref_for_offset (location_t loc, tr
> we can extract more optimistic alignment information
> by looking at the access mode. That would constrain the
> alignment of base + base_offset which we would need to
> - adjust according to offset.
> - ??? But it is not at all clear that prev_base is an access
> - that was in the IL that way, so be conservative for now. */
> + adjust according to offset. */
> align = get_pointer_alignment_1 (base, &misalign);
> + if (misalign == 0
> + && (TREE_CODE (prev_base) == MEM_REF
> + || TREE_CODE (prev_base) == TARGET_MEM_REF))
> + align = MAX (align, TYPE_ALIGN (TREE_TYPE (prev_base)));
> misalign += (double_int_sext (tree_to_double_int (off),
> TYPE_PRECISION (TREE_TYPE (off))).low
> * BITS_PER_UNIT);
>
> to mimic get_object_or_type_alignment.
>
> At least for the ipa-cp.c use I _do_ know there is no such access.
This one bootstrapped and tested ok on x86_64.
