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Workaround value-initialization in MSVC

The syntax splitPoints() should force the compiler to
value-initialize the array and because there is no
user defined c'tor it falls back on zero-initialization.

Unfortunatly this is broken in MSVC compilers, because
value initialization for non-POD types is not supported,
so left splitPoints un-initialized and add in split()
initialization of slavesPositions, that is the only
member not already set at split time.

This fixes an assert under MSVC when running with
more than one thread.

Spotted and reported by Jundery.

No functional change.
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1 parent c67fb8e commit 50a7200b18e96a6f0e2c2ee7fda017ea6f2f1c1f @mcostalba committed Feb 8, 2013
Showing with 4 additions and 1 deletion.
  1. +4 −1 src/thread.cpp
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@@ -19,6 +19,7 @@
#include <algorithm> // For std::count
#include <cassert>
+#include <cstring> // For memset
#include <iostream>
#include "movegen.h"
@@ -43,7 +44,7 @@ namespace { extern "C" {
// Thread c'tor starts a newly-created thread of execution that will call
// the the virtual function idle_loop(), going immediately to sleep.
-Thread::Thread() : splitPoints() {
+Thread::Thread() /* : splitPoints() */ { // Value-initialization bug in MSVC
searching = exit = false;
maxPly = splitPointsSize = 0;
@@ -280,6 +281,8 @@ void Thread::split(Position& pos, Stack* ss, Value alpha, Value beta, Value* bes
sp.cutoff = false;
sp.ss = ss;
+ memset(sp.slavesPositions, 0, sizeof(sp.slavesPositions));
+
// Try to allocate available threads and ask them to start searching setting
// 'searching' flag. This must be done under lock protection to avoid concurrent
// allocation of the same slave by another master.

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