https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104686
--- Comment #18 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #16)
> it doesn't make a difference for this testcase but profiling shows that
> allocnos_conflict_p is quite expensive so it's best to do it after the other
> continue checks like the following. I also notice that the comment of
> allocnos_conflict_p says
>
> /* Return TRUE if allocnos A1 and A2 conflicts. Here we are
> interesting only in conflicts of allocnos with intersected allocno
> classes. */
>
> so doing it after the ira_reg_classes_intersect_p check makes even more
> sense(?)
>
> diff --git a/gcc/ira-color.cc b/gcc/ira-color.cc
> index 8b6db1bb417..a5fd79484eb 100644
> --- a/gcc/ira-color.cc
> +++ b/gcc/ira-color.cc
> @@ -1572,15 +1572,14 @@ update_conflict_hard_regno_costs (int *costs, enum
> reg_class aclass,
> else
> gcc_unreachable ();
>
> + another_aclass = ALLOCNO_CLASS (another_allocno);
> if (another_allocno == from
> + || ALLOCNO_ASSIGNED_P (another_allocno)
> + || ALLOCNO_COLOR_DATA (another_allocno)->may_be_spilled_p
> + || ! ira_reg_classes_intersect_p[aclass][another_aclass]
> || allocnos_conflict_p (another_allocno, start))
> continue;
>
> - another_aclass = ALLOCNO_CLASS (another_allocno);
> - if (! ira_reg_classes_intersect_p[aclass][another_aclass]
> - || ALLOCNO_ASSIGNED_P (another_allocno)
> - || ALLOCNO_COLOR_DATA (another_allocno)->may_be_spilled_p)
> - continue;
> class_size = ira_class_hard_regs_num[another_aclass];
> ira_allocate_and_copy_costs
> (&ALLOCNO_UPDATED_CONFLICT_HARD_REG_COSTS (another_allocno),
>
>
> Now, what's more odd is that we sometimes have a nice bitmap representation
> for the conflicts but we always iterate. So it _seems_ we should be able
> to do sth like
>
> diff --git a/gcc/ira-color.cc b/gcc/ira-color.cc
> index 8b6db1bb417..682d1ef7562 100644
> --- a/gcc/ira-color.cc
> +++ b/gcc/ira-color.cc
> @@ -1352,9 +1352,23 @@ allocnos_conflict_p (ira_allocno_t a1, ira_allocno_t
> a2)
> {
> obj = ALLOCNO_OBJECT (a1, word);
> /* Take preferences of conflicting allocnos into account. */
> - FOR_EACH_OBJECT_CONFLICT (obj, conflict_obj, oci)
> - if (OBJECT_ALLOCNO (conflict_obj) == a2)
> - return true;
> + if (!OBJECT_CONFLICT_VEC_P (obj))
> + {
> + for (int w2 = 0; w2 < ALLOCNO_NUM_OBJECTS (a2); w2++)
> + {
> + ira_object_t obj2 = ALLOCNO_OBJECT (a2, w2);
> + if (OBJECT_CONFLICT_ID (obj2) >= OBJECT_MIN (obj)
> + && OBJECT_CONFLICT_ID (obj2) <= OBJECT_MAX (obj)
> + && TEST_MINMAX_SET_BIT (OBJECT_CONFLICT_BITVEC (obj),
> + OBJECT_CONFLICT_ID (obj2),
> + OBJECT_MIN (obj), OBJECT_MAX
> (obj)))
> + return true;
> + }
> + }
> + else
> + FOR_EACH_OBJECT_CONFLICT (obj, conflict_obj, oci)
> + if (OBJECT_ALLOCNO (conflict_obj) == a2)
> + return true;
> }
> return false;
> }
>
> which reduces compile-time from 10s to 1s for me ... the above should
> be split out so we can "optimally" use the bit test for
> object vs. allocno when possible.
>
> Vlad - any thoughts about the above two things? Shall I try to polish and
> optimize the bit test or would you be willing to pick those two speedups up?
Bootstrapped / tested ok on x86_64-unknown-linux-gnu.
