[Bug tree-optimization/110614] New: [14 Regression] ICE in vect_supportable_dr_alignment

["dje at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110614

            Bug ID: 110614
           Summary: [14 Regression] ICE in vect_supportable_dr_alignment
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dje at gcc dot gnu.org
  Target Milestone: ---
            Target: powerpc*-*-*

Beginning with

commit dd86a5a69cbda40cf76388a65d3317c91cb2b501
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Jun 22 11:40:46 2023 +0200

A number of GCC testsuite test cases ICE in vect_supportable_dr_alignment()

gcc/testsuite/gcc.dg/torture/pr68379.c

$ ./xgcc -B./ -S -O2 -mcpu=power7 pr68379.c 
during GIMPLE pass: vect
pr68379.c: In function ‘fn1’:
pr68379.c:6:1: internal compiler error: Segmentation fault
    6 | fn1 ()
      | ^~~
0x10c1d833 crash_signal
        /home/dje/src/gcc/gcc/toplev.cc:314
0x11b4ebd0 vect_supportable_dr_alignment(vec_info*, dr_vec_info*, tree_node*,
int)
        /home/dje/src/gcc/gcc/tree-vect-data-refs.cc:6833
0x11b53717 vect_enhance_data_refs_alignment(_loop_vec_info*)
        /home/dje/src/gcc/gcc/tree-vect-data-refs.cc:2044
0x10fc35bb vect_analyze_loop_2
        /home/dje/src/gcc/gcc/tree-vect-loop.cc:2783
0x10fc4d8f vect_analyze_loop_1
        /home/dje/src/gcc/gcc/tree-vect-loop.cc:3316
0x10fc56bb vect_analyze_loop(loop*, vec_info_shared*)
        /home/dje/src/gcc/gcc/tree-vect-loop.cc:3470
0x110174e7 try_vectorize_loop_1
        /home/dje/src/gcc/gcc/tree-vectorizer.cc:1064
0x110174e7 try_vectorize_loop
        /home/dje/src/gcc/gcc/tree-vectorizer.cc:1180
0x11017fa3 execute
        /home/dje/src/gcc/gcc/tree-vectorizer.cc:1296

The test cases succeed with Power8, Power9, or Power10, but ICE with
-mcpu=power7. command line option.