[Bug tree-optimization/91227] New: pointer relational expression not folded but equivalent inequality is

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91227

            Bug ID: 91227
           Summary: pointer relational expression not folded but
                    equivalent inequality is
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

GCC folds the pointer inequality in function f below to false but it doesn't
fold the equivalent relational expression in g.

$ cat b.c && gcc -O2 -S -Wall -fdump-tree-optimized=/dev/stdout b.c
void f (char *p)
{
  char a[3];
  if (p == a || p == a + 1 || p == a + 2 || p == a + 3)
    __builtin_abort ();
}


void g (char *p)
{
  char a[3];
  if (p >= a || p <= a + 3)
    __builtin_abort ();
} 

;; Function f (f, funcdef_no=0, decl_uid=1908, cgraph_uid=1, symbol_order=0)

f (char * p)
{
  <bb 2> [local count: 1073741824]:
  return;

}



;; Function g (g, funcdef_no=1, decl_uid=1912, cgraph_uid=2, symbol_order=1)

g (char * p)
{
  char a[3];
  _Bool _5;
  _Bool _6;
  _Bool _7;

  <bb 2> [local count: 1073741824]:
  _5 = &MEM <char[3]> [(void *)&a + 3B] >= p_1(D);
  _6 = &a <= p_1(D);
  _7 = _5 | _6;
  if (_7 != 0)
    goto <bb 3>; [0.00%]
  else
    goto <bb 4>; [100.00%]

  <bb 3> [count: 0]:
  __builtin_abort ();

  <bb 4> [local count: 1073741824]:
  a ={v} {CLOBBER};
  return;

}