1 files changed, 182 insertions, 9 deletions

diff --git a/src/command.c b/src/command.c
index d528994..4f81b10 100755
--- a/src/command.c
+++ b/src/command.c
@@ -32,6 +32,11 @@ Revision History:
 #define MAX_ARGS 32
 int g_eModeBeforeAnalyze = -1;
 
+// Bumped by EvalDnaCommand on every successful `evaldna read`/`load`;
+// EvalCommand compares against this to know its persistent eval-hash
+// cache needs clearing (see EvalCommand for details).
+ULONG g_uDnaGeneration = 0;
+
 typedef void (COMMAND_PARSER_FUNCTION)(CHAR *szInput,
                                        ULONG argc, 
                                        CHAR *argv[], 
@@ -497,19 +502,175 @@ Return value:
 
 **/
 {
-    SEARCHER_THREAD_CONTEXT *ctx;
+    // rgPawnHash/rgEvalHash are embedded arrays inside
+    // SEARCHER_THREAD_CONTEXT (tens of MB), so allocating fresh +
+    // InitializeSearcherContext's full memset on every call here was
+    // paying that cost per invocation.  Keep one persistent context
+    // for the life of the process and use the cheap
+    // ReInitializeSearcherContext (memmove position + zero counters
+    // only) on every call after the first, same pattern the real
+    // search path uses across moves.
+    //
+    // CORRECTNESS: ReInitializeSearcherContext does NOT clear
+    // ctx->rgEvalHash, so a stale score cached under previously-loaded
+    // DNA constants would otherwise be returned forever for any
+    // position hit more than once -- silently ignoring every
+    // subsequent `evaldna read`.  g_uDnaGeneration (bumped by
+    // EvalDnaCommand on a successful load) is compared here so a DNA
+    // change forces exactly one full re-init (i.e. one eval-hash
+    // clear per reload, not per position) instead of a stale hit.
+    static SEARCHER_THREAD_CONTEXT *ctx = NULL;
+    static ULONG uLastSeenDnaGeneration = (ULONG)-1;
     SCORE i;
 
-    ctx = SystemAllocateMemory(sizeof(SEARCHER_THREAD_CONTEXT));
-    if (NULL != ctx) 
+    if (NULL == ctx)
     {
+        ctx = SystemAllocateMemory(sizeof(SEARCHER_THREAD_CONTEXT));
+        if (NULL == ctx)
+        {
+            Trace("Out of memory.\n");
+            return;
+        }
         InitializeSearcherContext(pos, ctx);
-        i = Eval(ctx, -INFINITY, +INFINITY);
-        Trace("Static eval: %s\n", ScoreToString(i));
-        SystemFreeMemory(ctx);
-    } else {
-        Trace("Out of memory.\n");
+        uLastSeenDnaGeneration = g_uDnaGeneration;
     }
+    else if (uLastSeenDnaGeneration != g_uDnaGeneration)
+    {
+        InitializeSearcherContext(pos, ctx);
+        uLastSeenDnaGeneration = g_uDnaGeneration;
+    }
+    else
+    {
+        ReInitializeSearcherContext(pos, ctx);
+    }
+    i = Eval(ctx, -INFINITY, +INFINITY);
+    Trace("Static eval: %s\n", ScoreToString(i));
+}
+
+
+COMMAND(QSearchCommand)
+/**
+
+Routine description:
+
+    This function implements the 'qsearch' engine command.
+
+    Usage:
+
+        qsearch
+
+        This command takes no arguments and causes the engine to run
+        a quiescence search on the current board position and print
+        the resulting score.  Unlike `eval` (a static evaluation with
+        no search at all), this resolves captures/checks/promotions
+        first, the same way the real search does immediately before
+        calling Eval() -- so it's a much better proxy for "is this
+        position actually quiet" than comparing SEE-based capture
+        analysis to a static score.
+
+Parameters:
+
+    The COMMAND macro hides four arguments from the input parser:
+
+        CHAR *szInput : the full line of input
+        ULONG argc    : number of argument chunks
+        CHAR *argv[]  : array of ptrs to each argument chunk
+        POSITION *pos : a POSITION pointer to operate on
+
+Return value:
+
+    void
+
+**/
+{
+    // Same persistent-context + DNA-generation-invalidation pattern as
+    // EvalCommand (see its comment for the full rationale) -- this
+    // command is meant to be called at corpus scale from the eval
+    // tuner, so paying a fresh ~75MB memset per call would be the
+    // same 1000x throughput hit that command had before it was fixed.
+    static SEARCHER_THREAD_CONTEXT *ctx = NULL;
+    static ULONG uLastSeenDnaGeneration = (ULONG)-1;
+    CUMULATIVE_SEARCH_FLAGS *pf;
+    PLY_INFO *pi;
+    SCORE i;
+
+    if (NULL == ctx)
+    {
+        ctx = SystemAllocateMemory(sizeof(SEARCHER_THREAD_CONTEXT));
+        if (NULL == ctx)
+        {
+            Trace("Out of memory.\n");
+            return;
+        }
+        InitializeSearcherContext(pos, ctx);
+        uLastSeenDnaGeneration = g_uDnaGeneration;
+    }
+    else if (uLastSeenDnaGeneration != g_uDnaGeneration)
+    {
+        InitializeSearcherContext(pos, ctx);
+        uLastSeenDnaGeneration = g_uDnaGeneration;
+    }
+    else
+    {
+        ReInitializeSearcherContext(pos, ctx);
+    }
+
+    // QSearch is normally only ever entered from Search() one ply
+    // below the position it's evaluating (see search.c's "the only
+    // place Qsearch is entered" comment) -- it reads (pi-1)->mv to
+    // learn whether the side to move just got checked into this
+    // position, and asserts ctx->uPly > 0.  To call it directly on
+    // the root position, synthesize that one piece of ply-0 state:
+    // a fake "previous move" whose only job is to carry the correct
+    // checking-move flag, so QSearch's in-check handling matches the
+    // position's actual, real InCheck() status instead of silently
+    // taking the no-standpat path incorrectly for a position that IS
+    // in check (or vice versa).
+    ctx->uPly = 1;
+    memset(&ctx->sPlyInfo[0].mv, 0, sizeof(MOVE));
+    if (TRUE == InCheck(&ctx->sPosition, ctx->sPosition.uToMove))
+    {
+        ctx->sPlyInfo[0].mv.uMove |= 0x80000000;
+    }
+
+    pf = &ctx->sSearchFlags;
+    pi = &ctx->sPlyInfo[ctx->uPly];
+    pf->fCouldStandPat[BLACK] = pf->fCouldStandPat[WHITE] = FALSE;
+    pf->uQsearchNodes = pf->uQsearchDepth = 0;
+    pf->uQsearchCheckDepth = QPLIES_OF_NON_CAPTURE_CHECKS;
+    pi->fInQsearch = TRUE;
+
+    // QSearch's recursive move loop checks WE_SHOULD_STOP_SEARCHING,
+    // which reads the process-global g_MoveTimer -- normally set up
+    // by SetMoveTimerForSearch() at the start of every real search.
+    // This command is a standalone call outside that path, so without
+    // this g_MoveTimer is whatever state a prior real search left it
+    // in (e.g. an already-expired hard limit). Save/restore around
+    // the call so a `qsearch` invoked between real searches (e.g.
+    // interactive use after `go`) doesn't leave the timer in a
+    // "think forever" state for whatever search comes next.
+    //
+    // g_uHardExtendLimit is a second process-global with the same
+    // problem, and the one actually responsible for a bogus +MATE
+    // score on every call before this fix: CommonSearchInit's
+    // "uQsearchDepth >= g_uHardExtendLimit" too-deep check (see its
+    // comment) fires immediately when this is left at its zero-
+    // initialized default, since it's normally only ever set once
+    // per real search, inside RootSearch (g_uIterateDepth * 4) --
+    // a path this standalone command never runs through. Set it
+    // generously (MAX_PLY_PER_SEARCH; qsearch's own capture-only move
+    // generation makes runaway recursion a non-issue) for the
+    // duration of the call, same save/restore reasoning as the timer.
+    {
+        MOVE_TIMER SavedMoveTimer = g_MoveTimer;
+        ULONG uSavedHardExtendLimit = g_uHardExtendLimit;
+        SetMoveTimerToThinkForever();
+        g_uHardExtendLimit = MAX_PLY_PER_SEARCH;
+        i = QSearch(ctx, -INFINITY, +INFINITY);
+        g_MoveTimer = SavedMoveTimer;
+        g_uHardExtendLimit = uSavedHardExtendLimit;
+    }
+    Trace("Qsearch score: %s\n", ScoreToString(i));
 }
 
 
@@ -568,10 +729,16 @@ Return value:
             Trace("Error (missing argument)\n");
             return;
         }
-        if (!ReadEvalDNA(argv[2])) 
+        if (!ReadEvalDNA(argv[2]))
         {
             Trace("Error reading dna file.\n");
         } else {
+            // EvalCommand's persistent SEARCHER_THREAD_CONTEXT keeps
+            // its embedded eval hash alive across calls for speed; a
+            // DNA reload must invalidate stale cached scores from the
+            // old constants, which this generation bump signals it
+            // to do (see EvalCommand for the actual clear).
+            g_uDnaGeneration++;
             Trace("Loaded dna file \"%s\"\n", argv[2]);
             p = ExportEvalDNA();
             Log("(New) dna: %s\n", p);
@@ -2188,6 +2355,12 @@ COMMAND_PARSER_ENTRY g_ParserTable[] =
       TRUE,
       FALSE,
       "Learn a set of PSQT settings from a PGN file" },
+    { "qsearch",
+      QSearchCommand,
+      FALSE,
+      FALSE,
+      FALSE,
+      "Run a quiescence search on the current position" },
     { "quit",
       QuitCommand,
       TRUE,