[Bug tree-optimization/107972] New: backward propagation of finite property not performed

[drepper.fsp+rhbz at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107972

            Bug ID: 107972
           Summary: backward propagation of finite property not performed
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: drepper.fsp+rhbz at gmail dot com
  Target Milestone: ---

Here is another example where with the help of the FP ranger capabilities the
compiler should generate better code than it does today (trunk):

double f(double a, double b)
{
  if (!__builtin_isfinite(a))
    return -1.0;

  double res = a + b;
  if (! __builtin_isfinite(res))
    __builtin_unreachable();
  return res;
}

The condition guaranteed by the __builtin_unreachable implies that neither a
nor b cannot be finite.  Hence the initial comparison can be elided.

The same is true for - and * and also for the first operand of /.