[Bug middle-end/102075] New: fill_always_executed_in_1 incomplete computation

[Bug middle-end/102075] New: fill_always_executed_in_1 incomplete computation

[luoxhu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102075

            Bug ID: 102075
           Summary: fill_always_executed_in_1 incomplete computation
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: luoxhu at gcc dot gnu.org
  Target Milestone: ---

ALWAYS_EXECUTED_IN is not computed completely for nested loops.  Current design
will exit if an inner loop doesn't dominate outer loop's latch or exit after
exiting from inner loop, which caused early return from outer loop, then ALWAYS
EXECUTED blocks after inner loops are skipped.

For example, x->k should be move out of outer loop but doesn't.

struct X { int i; int j; int k;};

void foo(struct X *x, int n, int l)
{
  for (int j = 0; j < l; j++)
    {
      for (int i = 0; i < n; ++i)
        {
          int *p = &x->j;
          int tem = *p;
          x->j += tem * i;
        }
      int *r = &x->k;
      int tem2 = *r;
      x->k += tem2 * j;
    }
}


Discussion lists:

https://gcc.gnu.org/pipermail/gcc-patches/2021-August/577444.html

[Bug tree-optimization/102075] fill_always_executed_in_1 incomplete computation

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102075

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|middle-end                  |tree-optimization
             Status|UNCONFIRMED                 |NEW
           Keywords|                            |missed-optimization
   Last reconfirmed|                            |2021-08-26
     Ever confirmed|0                           |1

[Bug tree-optimization/102075] fill_always_executed_in_1 incomplete computation

[luoxhu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102075

luoxhu at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #1 from luoxhu at gcc dot gnu.org ---
Fixed by Richard’s r12-3313,  r12-3429 and r12-3430.