https://gcc.gnu.org/g:94ef5ce0a23707d5e9097a8f1c1d1fd54af9c58f
commit 94ef5ce0a23707d5e9097a8f1c1d1fd54af9c58f
Author: Alexandre Oliva <ol...@gnu.org>
Date: Tue Dec 10 06:49:32 2024 -0300
ifcombine field-merge: saturate align at load size
Diff:
---
gcc/gimple-fold.cc | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
index a31fc283d51b..8f7380928a4e 100644
--- a/gcc/gimple-fold.cc
+++ b/gcc/gimple-fold.cc
@@ -8204,16 +8204,21 @@ fold_truth_andor_for_ifcombine (enum tree_code code,
tree truth_type,
to be relative to a field of that size. */
first_bit = MIN (ll_bitpos, rl_bitpos);
end_bit = MAX (ll_bitpos + ll_bitsize, rl_bitpos + rl_bitsize);
+ HOST_WIDE_INT align = TYPE_ALIGN (TREE_TYPE (ll_inner));
+ /* Guard from types with wider-than-size alignment. We must not widen the
+ load beyond its total size. This is rare. */
+ while (align > BITS_PER_UNIT
+ && known_gt ((unsigned HOST_WIDE_INT)align,
+ tree_to_poly_uint64 (TYPE_SIZE (TREE_TYPE (ll_inner)))))
+ align /= 2;
if (get_best_mode (end_bit - first_bit, first_bit, 0, 0,
- TYPE_ALIGN (TREE_TYPE (ll_inner)), BITS_PER_WORD,
- volatilep, &lnmode))
+ align, BITS_PER_WORD, volatilep, &lnmode))
l_split_load = false;
else
{
/* Consider the possibility of recombining loads if any of the
fields straddles across an alignment boundary, so that either
part can be loaded along with the other field. */
- HOST_WIDE_INT align = TYPE_ALIGN (TREE_TYPE (ll_inner));
HOST_WIDE_INT boundary = compute_split_boundary_from_align
(align, ll_bitpos, ll_bitsize, rl_bitpos, rl_bitsize);
