Hi,
As PR102789 shows, when vectorizer does some peelings for alignment
in prologue, function vect_update_inits_of_drs would update the
inits of some drs. But as the failed case, we shouldn't update the
dr for simd_lane_access, it has the fixed-length storage mainly for
the main loop, the update can make the access out of bound and access
the unexpected elements.
I tried to test this broadly to ensure it's safe, since I was not
sure if it's reasonable to exclude all kinds of simd_lane_access drs.
The testings didn't catch any failures, I hope this is on the right
track.
It's bootstrapped and regtested on:
- x86_64-redhat-linux
- aarch64-linux-gnu
- powerpc64le-linux-gnu P9
- powerpc64-linux-gnu P8 and P7.
Is it ok for trunk?
BR,
Kewen
-----
gcc/ChangeLog:
PR tree-optimization/102789
* tree-vect-loop-manip.c (vect_update_inits_of_drs): Do not
update inits of simd_lane_access.
diff --git a/gcc/tree-vect-loop-manip.c b/gcc/tree-vect-loop-manip.c
index 4988c93fdb6..378b1026baa 100644
--- a/gcc/tree-vect-loop-manip.c
+++ b/gcc/tree-vect-loop-manip.c
@@ -1820,7 +1820,8 @@ vect_update_inits_of_drs (loop_vec_info loop_vinfo, tree
niters,
FOR_EACH_VEC_ELT (datarefs, i, dr)
{
dr_vec_info *dr_info = loop_vinfo->lookup_dr (dr);
- if (!STMT_VINFO_GATHER_SCATTER_P (dr_info->stmt))
+ if (!STMT_VINFO_GATHER_SCATTER_P (dr_info->stmt)
+ && !STMT_VINFO_SIMD_LANE_ACCESS_P (dr_info->stmt))
vect_update_init_of_dr (dr_info, niters, code);
}
}
