[Bug fortran/45425] Bounds check applied before MASK of WHERE construct

[mikael at gcc dot gnu dot org]

------- Comment #3 from mikael at gcc dot gnu dot org  2010-08-28 17:42 -------
Ouch!
We need some sort of lazy evaluation.
Like (pseudo-code)

bool scalar_ever_evaluated = false;
whatever_type scalar_value;

while(1)
  {
    /* loop handling stuff */

    if (scalar_ever_evaluated)
      {
        scalar_value = <whatever complicated expression>;
        scalar_ever_evaluated = true;
      }

    /* normal code using scalar_value */
  }


We have to move back se->pre into se->expr so that it is not moved outside the
loop. Or move it outside the loop conditionally and conditionally add se->pre
inside the loop while evaluating the scalar. 

BTW I thought there was already some where-specific code generation for scalar
values. 


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45425