[Bug tree-optimization/85891] New: [6.4.1 regression] Simple loop is not SLP-vectorized after r196872

[jason.vas.dias at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85891

            Bug ID: 85891
           Summary: [6.4.1 regression] Simple loop is not SLP-vectorized
                    after r196872
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jason.vas.dias at gmail dot com
  Target Milestone: ---

Building GCC 6.4.1 from gcc-6-branch of 20180521 (SVN Revision 260441) ,
for x86_64 under Linux (RHEL-7.5, glibc-2.17, binutils 2.30) ,
now gets testsuite failures:

FAIL: g++.dg/vect/slp-pr56812.cc  -std=c++98  scan-tree-dump-times slp1 "basic
block vectorized" 1

FAIL: g++.dg/vect/slp-pr56812.cc  -std=c++11  scan-tree-dump-times slp1 "basic
block vectorized" 1

FAIL: g++.dg/vect/slp-pr56812.cc  -std=c++14  scan-tree-dump-times slp1 "basic
block vectorized" 1

These tests succeed with GCC 7.3.1 and GCC 5.5.0 .