Avoid casting to char* in prefetch()

Funny enough, gcc __builtin_prefetch() expects
already a void*, instead Windows's _mm_prefetch()
requires a char*.

The patch allows to remove ugly casts from caller
sites.

No functional change.

src/misc.cpp

@@ -176,11 +176,11 @@ void start_logger(bool b) { Logger::start(b); }
 /// which can be quite slow.
 #ifdef NO_PREFETCH
 
-void prefetch(char*) {}
+void prefetch(void*) {}
 
 #else
 
-void prefetch(char* addr) {
+void prefetch(void* addr) {
 
 #  if defined(__INTEL_COMPILER)
    // This hack prevents prefetches from being optimized away by
@@ -189,7 +189,7 @@ void prefetch(char* addr) {
 #  endif
 
 #  if defined(__INTEL_COMPILER) || defined(_MSC_VER)
-  _mm_prefetch(addr, _MM_HINT_T0);
+  _mm_prefetch((char*)addr, _MM_HINT_T0);
 #  else
   __builtin_prefetch(addr);
 #  endif

src/misc.h

@@ -28,7 +28,7 @@
 #include "types.h"
 
 const std::string engine_info(bool to_uci = false);
-void prefetch(char* addr);
+void prefetch(void* addr);
 void start_logger(bool b);
 
 void dbg_hit_on(bool b);

src/position.cpp

@@ -774,7 +774,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
       // Update material hash key and prefetch access to materialTable
       k ^= Zobrist::psq[them][captured][capsq];
       st->materialKey ^= Zobrist::psq[them][captured][pieceCount[them][captured]];
-      prefetch((char*)thisThread->materialTable[st->materialKey]);
+      prefetch(thisThread->materialTable[st->materialKey]);
 
       // Update incremental scores
       st->psq -= psq[them][captured][capsq];
@@ -841,7 +841,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI
 
       // Update pawn hash key and prefetch access to pawnsTable
       st->pawnKey ^= Zobrist::psq[us][PAWN][from] ^ Zobrist::psq[us][PAWN][to];
-      prefetch((char*)thisThread->pawnsTable[st->pawnKey]);
+      prefetch(thisThread->pawnsTable[st->pawnKey]);
 
       // Reset rule 50 draw counter
       st->rule50 = 0;
@@ -988,7 +988,7 @@ void Position::do_null_move(StateInfo& newSt) {
   }
 
   st->key ^= Zobrist::side;
-  prefetch((char*)TT.first_entry(st->key));
+  prefetch(TT.first_entry(st->key));
 
   ++st->rule50;
   st->pliesFromNull = 0;

src/search.cpp

@@ -872,7 +872,7 @@ namespace {
       }
 
       // Speculative prefetch as early as possible
-      prefetch((char*)TT.first_entry(pos.key_after(move)));
+      prefetch(TT.first_entry(pos.key_after(move)));
 
       // Check for legality just before making the move
       if (!RootNode && !SpNode && !pos.legal(move, ci.pinned))
@@ -1238,7 +1238,7 @@ namespace {
           continue;
 
       // Speculative prefetch as early as possible
-      prefetch((char*)TT.first_entry(pos.key_after(move)));
+      prefetch(TT.first_entry(pos.key_after(move)));
 
       // Check for legality just before making the move
       if (!pos.legal(move, ci.pinned))