[Bug tree-optimization/86532] New: [9 Regression] Wrong code due to a wrong strlen folding starting with r262522

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86532

            Bug ID: 86532
           Summary: [9 Regression] Wrong code due to a wrong strlen
                    folding starting with r262522
           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: msebor at gcc dot gnu.org
  Target Milestone: ---

Following simple test-case is miscompiled:

$ cat part.c
static const char dwarf_scnnames[2][3] =
{
  [0] = "1",
  [1] = "12",
};

int main (int argc, char **argv)
{
  int cnt, x;
  for (cnt = 0; cnt < 2; cnt++)
    x += __builtin_strlen (dwarf_scnnames[cnt]);

  __builtin_printf ("value: %d\n", x);
  if (x != 3)
    __builtin_abort ();

  return 0;
}

$ gcc /tmp/part.c -O0 && ./a.out
value: 2
Aborted (core dumped)