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Fix incorrect assert(PvNode == (alpha != beta - 1))

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In case of a PvNode could happen that alpha == beta - 1,
for instance in case the same previous node was visited
with same beta during a non-pv search, the node failed low
and stored beta-1 in TT. Then the node is searched again
in PV mode, TT value beta-1 is retrieved and updates alpha
that now happens to be beta-1.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2012-01-22 11:33:53 +01:00
parent ec9b037e5f
commit 04ac1bcabe
1 changed files with 2 additions and 2 deletions
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4
src/search.cpp
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@@ -544,7 +544,7 @@ namespace {
const bool RootNode = (NT == Root || NT == SplitPointRoot);
assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
assert(PvNode == (alpha != beta - 1));
assert((alpha == beta - 1) || PvNode);
assert(depth > DEPTH_ZERO);
assert(pos.thread() >= 0 && pos.thread() < Threads.size());
@@ -1154,7 +1154,7 @@ split_point_start: // At split points actual search starts from here
assert(NT == PV || NT == NonPV);
assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
assert(PvNode == (alpha != beta - 1));
assert((alpha == beta - 1) || PvNode);
assert(depth <= DEPTH_ZERO);
assert(pos.thread() >= 0 && pos.thread() < Threads.size());