https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65478
Jan Hubicka <hubicka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|tree-optimization |ipa
Summary|crafty performance |[5 regression] crafty
|regression |performance regression
--- Comment #2 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
Martin: Looking into it, the parameter 4(ply)=2 and donull=true seems to be
used in calls starting the recursion:
/*
----------------------------------------------------------
| |
| now call Search to produce a value for this move. |
| |
----------------------------------------------------------
*/
begin_root_nodes=nodes_searched;
if (first_move) {
value=-ABSearch(-beta,-alpha,ChangeSide(wtm),
depth+extensions,2,DO_NULL);
if (abort_search) {
UnMakeMove(1,current_move[1],wtm);
return(alpha);
}
first_move=0;
}
else {
value=-ABSearch(-alpha-1,-alpha,ChangeSide(wtm),
depth+extensions,2,DO_NULL);
if (abort_search) {
UnMakeMove(1,current_move[1],wtm);
return(alpha);
}
if ((value > alpha) && (value < beta)) {
value=-ABSearch(-beta,-alpha,ChangeSide(wtm),
depth+extensions,2,DO_NULL);
if (abort_search) {
UnMakeMove(1,current_move[1],wtm);
return(alpha);
}
}
}
While it recursively call itself with alternating players and sometimes drops
to !DO_NULL.
Intuitively, clonning the function specializing for first iteration of
recursion is like loop peeling and that is already done (not particularly well)
by recursive inlining.
I would suggest we may disable/add negative hint for cloning in the case where
the specialized function will end up calling unspecialized version of itself
with non-cold edge.
We also may consider adding bit of negative hints for cases where cloning would
turn function called once (by noncold edge) to a function called twice.
The same may be done with inliner, but that would even more reduce changes that
ipa-split produced split functions will actually get partially inlined.
Function is inlined by 4.9:
Considering NextMove/2405 with 284 size
to be inlined into Search.constprop/4352 in unknown:-1
Estimated badness is -128, frequency 0.69.
Badness calculation for Search.constprop/4352 -> NextMove/2405
size growth 273, time 174 inline hints: cross_module array_index
-128: guessed profile. frequency 0.694000, benefit 1.771337%, time w/o
inlining 621, time w inlining 610 overall growth 266 (current) 266 (original)
Accounting size:228.00, time:104.18 on predicate:(op4 <= 62)
Accounting size:4.00, time:4.13 on predicate:(op2 changed) &&
(op4 <= 62)
Accounting size:2.00, time:1.03 on predicate:(op2 == 0) && (op4
<= 62)
Accounting size:2.00, time:1.03 on predicate:(op2 != 0) && (op4
<= 62)
I am marking it as a regression thus and changing component to IPA.
