[Bug c/96740] frexp, modf, and remquo missing attribute nonnull

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96740

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic,
                   |                            |missed-optimization

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Besides the missing warnings the absence of the attribute also means that
subsequent tests in the callers of the functions for the pointers being null
are not optimized away as they could be if the functions made use of attribute
nonnull:

$ cat z.c && gcc -O2 -S -Wall -fdump-tree-optimized=/dev/stdout z.c
double f0 (double x, int *p)
{
  double y = __builtin_frexp (x, p);
  if (!p) __builtin_abort ();      // not eliminated
  return y;

}
double f2 (const char *s)
{ 
  double x = __builtin_nan (s);
  if (!s) __builtin_abort ();      // eliminated
  return x;
}

;; Function f0 (f0, funcdef_no=0, decl_uid=1932, cgraph_uid=1, symbol_order=0)

f0 (double x, int * p)
{
  double y;

  <bb 2> [local count: 1073741824]:
  y_5 = __builtin_frexp (x_2(D), p_3(D));
  if (p_3(D) == 0B)
    goto <bb 3>; [0.00%]
  else
    goto <bb 4>; [100.00%]

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

  <bb 4> [local count: 1073741824]:
  return y_5;

}



;; Function f2 (f2, funcdef_no=1, decl_uid=1936, cgraph_uid=2, symbol_order=1)

f2 (const char * s)
{
  double x;

  <bb 2> [local count: 1073741824]:
  x_2 = __builtin_nan (s_1(D)); [tail call]
  return x_2;

}