http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47397
--- Comment #10 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-21
16:21:55 UTC ---
You can play with a cleanup patch I have lying around, queued for 4.7:
Index: emit-rtl.c
===================================================================
*** emit-rtl.c (revision 169088)
--- emit-rtl.c (working copy)
*************** set_mem_attributes_minus_bitpos (rtx ref
*** 1611,1654 ****
/* We can set the alignment from the type if we are making an object,
this is an INDIRECT_REF, or if TYPE_ALIGN_OK. */
! if (objectp || TREE_CODE (t) == INDIRECT_REF || TYPE_ALIGN_OK (type))
! align = MAX (align, TYPE_ALIGN (type));
!
! else if (TREE_CODE (t) == MEM_REF)
{
! tree op0 = TREE_OPERAND (t, 0);
! if (TREE_CODE (op0) == ADDR_EXPR
! && (DECL_P (TREE_OPERAND (op0, 0))
! || CONSTANT_CLASS_P (TREE_OPERAND (op0, 0))))
! {
! if (DECL_P (TREE_OPERAND (op0, 0)))
! align = DECL_ALIGN (TREE_OPERAND (op0, 0));
! else if (CONSTANT_CLASS_P (TREE_OPERAND (op0, 0)))
! {
! align = TYPE_ALIGN (TREE_TYPE (TREE_OPERAND (op0, 0)));
! #ifdef CONSTANT_ALIGNMENT
! align = CONSTANT_ALIGNMENT (TREE_OPERAND (op0, 0), align);
! #endif
! }
! if (TREE_INT_CST_LOW (TREE_OPERAND (t, 1)) != 0)
! {
! unsigned HOST_WIDE_INT ioff
! = TREE_INT_CST_LOW (TREE_OPERAND (t, 1));
! unsigned HOST_WIDE_INT aoff = (ioff & -ioff) * BITS_PER_UNIT;
! align = MIN (aoff, align);
! }
! }
! else
/* ??? This isn't fully correct, we can't set the alignment from the
type in all cases. */
align = MAX (align, TYPE_ALIGN (type));
}
- else if (TREE_CODE (t) == TARGET_MEM_REF)
- /* ??? This isn't fully correct, we can't set the alignment from the
- type in all cases. */
- align = MAX (align, TYPE_ALIGN (type));
-
/* If the size is known, we can set that. */
if (TYPE_SIZE_UNIT (type) && host_integerp (TYPE_SIZE_UNIT (type), 1))
size = GEN_INT (tree_low_cst (TYPE_SIZE_UNIT (type), 1));
--- 1611,1628 ----
/* We can set the alignment from the type if we are making an object,
this is an INDIRECT_REF, or if TYPE_ALIGN_OK. */
! if (!TYPE_P (t))
{
! align = MAX (align, get_object_alignment (t, BIGGEST_ALIGNMENT));
! if (objectp || TYPE_ALIGN_OK (type))
! align = MAX (align, TYPE_ALIGN (type));
! else if (TREE_CODE (t) == TARGET_MEM_REF
! || TREE_CODE (t) == MEM_REF)
/* ??? This isn't fully correct, we can't set the alignment from the
type in all cases. */
align = MAX (align, TYPE_ALIGN (type));
}
/* If the size is known, we can set that. */
if (TYPE_SIZE_UNIT (type) && host_integerp (TYPE_SIZE_UNIT (type), 1))
size = GEN_INT (tree_low_cst (TYPE_SIZE_UNIT (type), 1));
but I wonder why we are not falling into the
- else if (TREE_CODE (t) == TARGET_MEM_REF)
- /* ??? This isn't fully correct, we can't set the alignment from the
- type in all cases. */
- align = MAX (align, TYPE_ALIGN (type));
case right now, or what I am missing.
Ah, for the offsetted load the vectorizer uses a 64bit aligned type.
So it either cannot compute the alignment or fails to use an aligned type.
