[Bug tree-optimization/88792] New: [9 Regression] wrong-code in RPO VN since r263875

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88792

            Bug ID: 88792
           Summary: [9 Regression] wrong-code in RPO VN since r263875
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
                CC: rguenth at gcc dot gnu.org
  Target Milestone: ---

Isolated from vim package:

$ cat r.c
int one = 1;

char
__attribute__((noipa))
foo(char v)
{
  int modec;

  if (one)
  {
    modec = ((v < 'A' || v > 'Z') ? v : v + ('a' - 'A'));
    if (modec != 't' && modec != 'c' && modec != 'g')
      modec = 0;
  }
  else
    modec = 'g';

  return modec;
}

int main(int argc, char **argv)
{
  char c = 't';
  int r = foo (c);

  __builtin_printf ("called for '%c', returned: %c\n", c, r);
  if (r != c)
    __builtin_abort ();

  return 0;
}

$ gcc -O2 r.c  -O2 && ./a.out
called for 't', returned: 
Aborted (core dumped)