From: Marco Costalba <mcostalba@gmail.com>
Date: Fri, 27 Nov 2009 10:54:07 +0000 (+0100)
Subject: Better document previous patch
X-Git-Url: http://winboard.nl/cgi-bin?a=commitdiff_plain;h=ae6157fcf33f840361acb24f98ea37299b3eaa36;p=fairystockfish.git

Better document previous patch

If tte->move() != MOVE_NONE then tte->move() == ttMove

What could happen is that we have a ttMove without a tte, or,
we have a tte but tte->move() == MOVE_NONE

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
---

diff --git a/src/search.cpp b/src/search.cpp
index 7eb0430..7ffdadc 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1139,9 +1139,8 @@ namespace {
         ttMove = ss[ply].pv[ply];
         tte = TT.retrieve(pos.get_key());
 
-        // Following assert could fail, for instance when we have
-        // moveCount == 0 we return without saving a TT entry.
-        /* assert(tte); */
+        // If tte->move() != MOVE_NONE then it equals ttMove
+        assert(!(tte && tte->move()) || tte->move() == ttMove);
     }
 
     // Initialize a MovePicker object for the current position, and prepare
@@ -1170,8 +1169,6 @@ namespace {
       // To verify this we do a reduced search on all the other moves but the ttMove,
       // if result is lower then TT value minus a margin then we assume ttMove is the
       // only one playable. It is a kind of relaxed single reply extension.
-      // Note that could be ttMove != tte->move() due to IID, so we always use tte->move()
-      // to avoid aliases when we probe tte->depth() and tte->type()
       if (   depth >= 8 * OnePly
           && tte
           && move == tte->move()
@@ -1476,8 +1473,6 @@ namespace {
       // To verify this we do a reduced search on all the other moves but the ttMove,
       // if result is lower then TT value minus a margin then we assume ttMove is the
       // only one playable. It is a kind of relaxed single reply extension.
-      // Note that could be ttMove != tte->move() due to IID, so we always use tte->move()
-      // to avoid aliases when we probe tte->depth() and tte->type()
       if (   depth >= 8 * OnePly
           && tte
           && move == tte->move()