This is a follow up to commit 5c9669a0e6c respectively discussion
https://gcc.gnu.org/pipermail/gcc-patches/2020-June/549132.html
In case that an alignment constraint is less than the size of a
corresponding scalar type, ensure that we advance at least by one
iteration. For example, on s390x we have for a long double an alignment
constraint of 8 bytes whereas the size is 16 bytes. Therefore,
TARGET_ALIGN / DR_SIZE equals zero resulting in an infinite loop which
can be reproduced by the following MWE:
extern long double *a;
extern double *b;
void fun(void) {
for (int i = 0; i < 42; i++)
a[i] = b[i];
}
Increasing the number of peelings in each iteration at least by one
fixes the issue for me. Any comments?
Bootstrapped and regtested on s390x.
gcc/ChangeLog:
* tree-vect-data-refs.c (vect_enhance_data_refs_alignment):
Ensure that loop variable npeel_tmp advances in each iteration.
---
gcc/tree-vect-data-refs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index e35a215e042..a78ae61d1b0 100644
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -1779,7 +1779,7 @@ vect_enhance_data_refs_alignment (loop_vec_info
loop_vinfo)
{
vect_peeling_hash_insert (&peeling_htab, loop_vinfo,
dr_info, npeel_tmp);
- npeel_tmp += target_align / dr_size;
+ npeel_tmp += MAX (1, target_align / dr_size);
}
one_misalignment_known = true;
--
2.25.3
