https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104686
--- Comment #16 from Richard Biener <rguenth at gcc dot gnu.org> --- 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?