It is redundant with splitPoint->slaves[].
Also move slaves[MAX_THREADS] among the shared data in
SplitPoint definition as it should have been already.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Small twekas to make the two searches as similar as
possible.
Also removed an useless setting of mateKiller in sp_search()
No functional change (tested with FakeSplit)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
We don't need to comment/uncomment code, just
set FakeSplit bool to true to enable faked split.
Also reintroduced some asserts and cleaned up a bit.
Tested that with FakeSplit = true we have reproducible
finger printing even in SMP.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Also introduce a new rule:
In sp_search() always must hold: sp->alpha < sp->beta
Should fix some rear but very nasty races
To keep everything in sync, search() is also modified to
obey this rule. Because this affects only PV-nodes, should
have zero meaning to speed.
No functional change in fake mode
Regression test after 854 games
Mod vs Orig 433 - 421, no crashes.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
We don't need to evaluate the position if it
is already cached in TT. We already do this
in non-PV case.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This is what actually is.
A standard naming convention suggests to name a variable
with someting resembling _what_ the variable is and not
_how_ the variable is used. This normally results
in easier to read code.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
More aggressive LMR reductions.
Tested at different time controls:
- Tested with 1CPU 1+0, after 3000 games, result was +12 ELO
- Tested this with 4CPU 1+0 and got sth around 5-10 ELO increase
- Last one at long time control,after ~1000 games with 10+0 result is:
Orig - Mod: 491 - 520 (+10 elo)
A testing marathon by Joona for this important change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Master thread returns from idle_loop() when sp->cpus == 0,
but cpus is decremented by slave threads under sp->lock,
so it could happen that we return in split(), where we release
the split point, with sp->lock still held.
This patch guarantees that sp->lock is released when returning
to split().
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Almost no change and simplifies a bit the code.
After 961 games at 1+0
Mod vs Orig +156 =650 -146 +4 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Re-save the same TT entry if value is usable and allow
us to cut-off, it means that entry is valuable and
we want to keep it fresh updating the 'generation'
parameter up to the current value.
Patch suggested by J. Wesley Cleveland and better
clarified by Miguel A. Ballicora.
After 999 games at 1+0 64MB hash size
Mod vs Orig +167 =677 -155 +4 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Should be a very minor change, but there is a small
functional change because futility_margin() is used in more
places then in the pruning formula.
After 999 games at 1+0
Mod vs Orig +167 =678 -154 +5 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Revert all the patches that introduced the change and
more or less fixed the zugzwang issue.
There is a gain against last current version and we
can remove a lot of code.
After 979 games at 1+0 on my QUAD
Mod vs Orig +152 =688 -139 +5 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Real search is considered of higher quality then null
search one.
This allows to fix the zugzwang issue with a minimal
impact on ELO.
Zugzwang verified on position:
8/7P/8/8/K2b4/p7/1k6/1B6 b - -
After 999 games at 1+0 on my QUAD
Mod vs Orig(94bb196) +168 =657 -174 -2 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Is a boolean option that when set allows Stockfish
to select the best book move across the possible ones.
Feature requested by Salvo Spitaleri.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Avoid incorrect mate scores in positions like
BK5/1R4b1/2k1Np2/3p3b/2p3pq/p1rB4/n2n1p2/8 w - -
Thanks for Jouni Uski for reporting the problem
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This is the world's fussiest compiler with +w1
Warnings reported by Richard Lloyd.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Add an UCI option "Zugzwang detection" OFF by default that
enables correct detection of zugzwang.
This is just to let 1.7.1 be 100% compatible with 1.7 and
should be removed after release.
Verified 100% functional equivalent to 1.7
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It fails in test position:
8/7P/8/8/K2b4/p7/1k6/1B6 b - -
Not clear why but we revert because it fixes the issue.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In this case use a normal VALUE_TYPE_LOWER TT type instead of
VALUE_TYPE_NS_LO. This allow us to TT cut-off in a bit more nodes.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This patch fixes an issue with zugzwang well explained by Tord:
"Assume that a zugzwang position occurs at iteration N,
at a search depth d, with d < 6*OnePly. The null move search
fails high, and no verification search is done, because the
depth is too small. The position gets stored in the transposition
table with a good score and a depth of d.
Now, consider what happens when the same position occurs at iteration
N+1, this time with a depth of d+OnePly (i.e. one ply deeper than at
the previous iteration). Once again, the null move search fails
high. The point is that the verification search will also fail high,
because of an instant transposition table cutoff caused by the value
stored in the TT during the previous iteration."
With this patch we simply do not allow TT cutoffs at the root node
of a null move verification search if the TT value was found by a
null search.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Add VALUE_TYPE_NS_LO to enum ValueType and use it when
saving in TT a value from a null search.
Currently no action is performed, the next patch will enable
the new type.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Reported warning is:
warning #2514-D: pointless comparison of unsigned
integer with a negative constant
Spotted by Richard Lloyd.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Use full depth, not reduced one. This allows
to avoid to do a null search when in the same
position and at the same or bigger depth the
null search failed high.
A very small increase, if any.
After 963 games at 1+0
Mod vs Orig: +158 =657 -147 +4 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
After previous patch we don't need any more the call parameters.
This fixes a couple of warnings under MSVC.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
After 500 games at 5+0 on my QUAD (3 days) there
is no difference with old version, so probably it
is a feature that doesn't scale with search depth.
So revert for now, perhaps we should readd under a
different form.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
MSVC complains about an implicit conversion from double to int.
Also small comments tweaks.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
In the beginning use milder reduction and at the end be
more aggressive.
After 1500 games on Joona's QUAD
Mod - Orig: 791 - 720 +16 elo
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Causes very small functional change which is not observable with
our usual set of test positions.
However change is observable fx. with following position:
4k3/3r4/5Q2/6K1/8/8/8/8 w - - 0 1
go depth 24
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
If null search fails high return null value instead of beta.
With TT hash there may be a small advantage for fail-soft since
storing slightly better bounds may cause slightly more hash hits.
After 990 games at 1+0
Mod vs Orig +171 =665 -154 +6 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Array castleRightsMask[] is not static because it can
be different for different positions, so let it be
a Position member data. This allows to remove tricky
hacks to take in account that although it was defined
static it could change.
Theoretically now copying a position is a bit slower because
we need to copy also an array of 64 integers, but because in
split() we don't copy the position anymore, but just keep the
pointer, the added burden is not mesurable even in MP case.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
