From: Kewen Lin <linkw@linux.ibm.com>
Date: Tue, 26 Oct 2021 02:05:02 +0000 (-0500)
Subject: vect: Don't update inits for simd_lane_access DRs [PR102789]
X-Git-Tag: releases/gcc-11.3.0~674
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7cb3b868f702e63e53ee1880c6b8a61676144395;p=thirdparty%2Fgcc.git

vect: Don't update inits for simd_lane_access DRs [PR102789]

As PR102789 shows, when vectorizer does some peelings for alignment
in prologues, 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 element.

gcc/ChangeLog:

	PR tree-optimization/102789
	* tree-vect-loop-manip.c (vect_update_inits_of_drs): Do not
	update inits of simd_lane_access.

(cherry picked from commit f3dbd3f36d55178d0a9e4431043cbc950524969a)
---

diff --git a/gcc/tree-vect-loop-manip.c b/gcc/tree-vect-loop-manip.c
index 012f48bd4870..d57108be5787 100644
--- a/gcc/tree-vect-loop-manip.c
+++ b/gcc/tree-vect-loop-manip.c
@@ -1822,7 +1822,8 @@ 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);
     }
 }