From: protonspring <mike@whiteley.org>
Date: Sun, 17 Jun 2018 02:26:25 +0000 (-0600)
Subject: Remove make_bitboard()
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=af6072c8b7e849c43b69dc286bcc0de6d9b453a1

Remove make_bitboard()

In current master, the function make_bitboard() does nothing apart from
helping initialize the SquareBB[] array. This seems like an unnecessary
abstraction layer.

The advantage of make_bitboard() is we can define a bitboard, in a simple
and general way, not only from a single square but also from a list of
squares. It is more elegant, faster and  readable than combining multiple
SquareBB explicitly, but the last complex use case in evaluation was
simplified away a few months ago.

If make_bitboard() becomes useful again to define complicated bitboards,
it will be easy enough to reintroduce it using this pull request as
an implementation reference.

No functional change.
---

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index b19d401a..96f0517f 100644
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -89,7 +89,7 @@ void Bitboards::init() {
       PopCnt16[i] = (uint8_t) popcount16(i);
 
   for (Square s = SQ_A1; s <= SQ_H8; ++s)
-      SquareBB[s] = make_bitboard(s);
+      SquareBB[s] = (1ULL << s);
 
   for (File f = FILE_A; f <= FILE_H; ++f)
       FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB;
diff --git a/src/bitboard.h b/src/bitboard.h
index 7ae1effd..54df6c2d 100644
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -155,16 +155,6 @@ inline Bitboard file_bb(Square s) {
 }
 
 
-/// make_bitboard() returns a bitboard from a list of squares
-
-constexpr Bitboard make_bitboard() { return 0; }
-
-template<typename ...Squares>
-constexpr Bitboard make_bitboard(Square s, Squares... squares) {
-  return (1ULL << s) | make_bitboard(squares...);
-}
-
-
 /// shift() moves a bitboard one step along direction D (mainly for pawns)
 
 template<Direction D>