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Retire quick_evaluate()

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No change in functionality signature

The only functional change is that when we reach PLY_MAX,
we now return VALUE_DRAW instead of evaluating position.

But we reach PLY_MAX only when position is dead drawn and
transposition table is filled with draw scores, so this
shouldn't matter at all.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Joona Kiiski
2010-01-17 13:55:10 +02:00
committed by Marco Costalba
parent d457594197
commit 000a975eaf
3 changed files with 17 additions and 41 deletions
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42
src/search.cpp
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@@ -1098,7 +1098,6 @@ namespace {
assert(threadID >= 0 && threadID < ActiveThreads);
Move movesSearched[256];
EvalInfo ei;
StateInfo st;
const TTEntry* tte;
Move ttMove, move;
@@ -1119,12 +1118,9 @@ namespace {
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
if (pos.is_draw())
if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
if (ply >= PLY_MAX - 1)
return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
// Mate distance pruning
oldAlpha = alpha;
alpha = Max(value_mated_in(ply), alpha);
@@ -1349,12 +1345,9 @@ namespace {
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
if (pos.is_draw())
if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
if (ply >= PLY_MAX - 1)
return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
// Mate distance pruning
if (value_mated_in(ply) >= beta)
return beta;
@@ -1379,22 +1372,24 @@ namespace {
isCheck = pos.is_check();
ei.futilityMargin = Value(0); // Manually initialize futilityMargin
// Evaluate the position statically
if (isCheck)
staticValue = quick_evaluate(pos);
else if (tte && (tte->type() & VALUE_TYPE_EVAL))
staticValue = value_from_tt(tte->value(), ply);
else
staticValue = evaluate(pos, ei, threadID);
// Calculate depth dependant futility pruning parameters
const int FutilityMoveCountMargin = 3 + (1 << (3 * int(depth) / 8));
const int FutilityValueMargin = 112 * bitScanReverse32(int(depth) * int(depth) / 2);
// Enhance score accuracy with TT value if possible
ss[ply].eval = staticValue;
futilityValue = staticValue + FutilityValueMargin;
staticValue = refine_eval(tte, staticValue, ply);
// Evaluate the position statically
if (isCheck)
ss[ply].eval = VALUE_NONE;
else
{
if (tte && (tte->type() & VALUE_TYPE_EVAL))
staticValue = value_from_tt(tte->value(), ply);
else
staticValue = evaluate(pos, ei, threadID);
ss[ply].eval = staticValue;
futilityValue = staticValue + FutilityValueMargin;
staticValue = refine_eval(tte, staticValue, ply); // Enhance accuracy with TT value if possible
}
// Null move search
if ( allowNullmove
@@ -1660,12 +1655,9 @@ namespace {
if (AbortSearch || thread_should_stop(threadID))
return Value(0);
if (pos.is_draw())
if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
if (ply >= PLY_MAX - 1)
return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
// Transposition table lookup. At PV nodes, we don't use the TT for
// pruning, but only for move ordering.
tte = TT.retrieve(pos.get_key());