[Bug rtl-optimization/68435] New: [6 Regression] Missed if-conversion optimization

[afomin.mailbox at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68435

            Bug ID: 68435
           Summary: [6 Regression] Missed if-conversion optimization
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: afomin.mailbox at gmail dot com
                CC: izamyatin at gmail dot com, kyrylo.tkachov at arm dot com,
                    ysrumyan at gmail dot com
  Target Milestone: ---
             Build: x86_64-linux-gnu

Created attachment 36772
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36772&action=edit
A reproducer

Given the following code compiled with -fif-conversion, we miss if-conversion
opportunity since r228194.

int
foo(char *p1, char *p2, int n)
{
  int s = 0;
  int v;
  int i;

  for (i = 0; i < n; i++) {
    v = p1[i] - p2[i];
    if (v >= 0)
      s += v;
    else
      s -= v;
    p1 = p2++;
  }

  return s;
}