[Bug rtl-optimization/68547] New: incorrect optimization

[jan.smets@alcatel-lucent.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68547

            Bug ID: 68547
           Summary: incorrect optimization
           Product: gcc
           Version: 5.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jan.smets@alcatel-lucent.com
  Target Milestone: ---

Created attachment 36841
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36841&action=edit
test case

$ g++ test.cc -o test -O2 -Wall && ./test
DEL element[1]=200 volatile
DEL element[1]=200 last_element_index=2 (should be 2) volatile
DEL element[1]=200
DEL element[1]=200 last_element_index=1 (should be 2)
$ g++ test.cc -o test -O0 -Wall && ./test
DEL element[1]=200 volatile
DEL element[1]=200 last_element_index=2 (should be 2) volatile
DEL element[1]=200
DEL element[1]=200 last_element_index=2 (should be 2)