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>
Under gcc we have:
warning: dereferencing type-punned pointer will break
strict-aliasing rules
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>
In this form it is even more evident we have some
issue there to be fixed sooner then later....
No functional change.
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>
Also don't use __cpuid() intrinsic for Intel under
Linux because gives wrong results when detecting HT,
use the gcc version instead. Finally clean up the code.
Error was due to changed __cpuid() signature for
gcc compiler.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This will allow to use the function also for other
purposes then detecting POPCNT.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It will be used by future patches and also rearranges some
half cooked code that mistakenly ended up in master in the
past.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Currently, in case of fail high/low we research with
a window increased by 2*AspirationDelta at first
attempt, this patch instead makes the research be
done with an increase of just AspirationDelta size,
in case of a consecutive fail we will widen to
2*AspirationDelta and so on.
After Joona's test:
Orig - Mod: 850 - 890
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
One for failing highs and one for failing lows, this
should reduce average window size in case of positions
that fail first high and then low (or the contrary).
After ~2000 games on Joona's quad we have:
Mod - Orig: 1012- 975 (+6 elo)
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Instead to leave uninitialized or scattered in the code
as is the case for ExtraSearchTime.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Currently we use original sorting after a fail low to
research at wider window. This patch instead sorts the
moves according to the last available move's scores.
Strangely no functional change, but should be.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Changed FutilityMarginsMatrix dimensions to be a power of two
so that compiler can produce a faster accessing code.
Introduced print_pv_info() to remove some redundant code in
root_search()
Remaining stuff is triviality and documentation tweaks.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Under Windows we use CreateThread() to setup threads and
we pass a pointer to a variable that receives the thread
identifier, but this parameter is optional and we don't
use it, so remove it.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It happens that NULL is 0, but the conventional meaning is of
a zero pointer, so repleace with an explicit 0 integer value.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Consider sligtly negative captures as good if at low
depth and far from beta.
After 999 games at 1+0
Mod vs Orig +169 =694 -136 +11 ELO
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
It raises an assert under Windows, it is not clear why but it
happens that idle_loop() is called with incorrect threadID and
the assert triggered is:
assert(threadID >= 0 && threadID < MAX_THREADS);
So revert the patch for now, but we should understand why it
fails.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
We can't do it with full guarantee anyway because
there is always a possible race between the setting of
state to THREAD_SLEEPING and actual sleeping.
So just remove the not perfect code to avoid misunderstandings.
This reflects what we have done in wake_sleeping_threads() in
the previous patch.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
Currently there is no guarantee that threads are sleeping
when calling wake_sleeping_threads() because put_threads_to_sleep()
returns without waiting for threads to actually sleep.
Assert can be easily triggered calling put_threads_to_sleep() and
wake_sleeping_threads() in a tight loop.
No functional change.
Signed-off-by: Marco Costalba <mcostalba@gmail.com>
