https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113396
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot
gnu.org
--- Comment #30 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's LIM2 which applies store-motion to m[0] but keeps m[p] in the loop.
Then with range-info for the int128 of [0, +INF] we get into
get_ref_base_and_extent:
query = get_range_query (cfun);
if (TREE_CODE (index) == SSA_NAME
&& (low_bound = array_ref_low_bound (exp),
poly_int_tree_p (low_bound))
&& (unit_size = array_ref_element_size (exp),
TREE_CODE (unit_size) == INTEGER_CST)
&& query->range_of_expr (vr, index)
&& !vr.varying_p ()
&& !vr.undefined_p ())
{
wide_int min = vr.lower_bound ();
wide_int max = vr.upper_bound ();
poly_offset_int lbound = wi::to_poly_offset (low_bound);
/* Try to constrain maxsize with range information. */
offset_int omax
= offset_int::from (max, TYPE_SIGN (TREE_TYPE (index)));
if (known_lt (lbound, omax))
{
poly_offset_int rmaxsize;
rmaxsize = (omax - lbound + 1)
* wi::to_offset (unit_size) << LOG2_BITS_PER_UNIT;
if (!known_size_p (maxsize)
|| known_lt (rmaxsize, maxsize))
and compute rmaxsize == 0.
What's definitely questionable here is the offset_int::from, though it
fits. But omax - lbound + 1 overflows to zero here. It's probably
better to use widest-int here, even if that's possibly slower than
offset_int. Or ensure offset_int has one more bit than required for
the index type (offset_int has 64bit + 3bits, so 128bits).
