From: protonspring <mike@whiteley.org>
Date: Mon, 14 Jan 2019 14:03:31 +0000 (-0700)
Subject: Simplify pawn moves (#1900)
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=3732c55c18fd74981370dc55b7b46ec8a05ad5bf

Simplify pawn moves (#1900)

If we define dcCandidates with & pawnsNotOn7,
we don't have to & it both times.

This seems more clear to me as well.

Tested for no regression.
STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 44042 W: 9663 L: 9585 D: 24794
http://tests.stockfishchess.org/tests/view/5c21d9120ebc5902ba12e84d

No functional change.
---

diff --git a/src/movegen.cpp b/src/movegen.cpp
index 5ed24893..2f7c55c8 100644
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -93,10 +93,10 @@ namespace {
             // if the pawn is not on the same file as the enemy king, because we
             // don't generate captures. Note that a possible discovery check
             // promotion has been already generated amongst the captures.
-            Bitboard dcCandidates = pos.blockers_for_king(Them);
-            if (pawnsNotOn7 & dcCandidates)
+            Bitboard dcCandidateQuiets = pos.blockers_for_king(Them) & pawnsNotOn7;
+            if (dcCandidateQuiets)
             {
-                Bitboard dc1 = shift<Up>(pawnsNotOn7 & dcCandidates) & emptySquares & ~file_bb(ksq);
+                Bitboard dc1 = shift<Up>(dcCandidateQuiets) & emptySquares & ~file_bb(ksq);
                 Bitboard dc2 = shift<Up>(dc1 & TRank3BB) & emptySquares;
 
                 b1 |= dc1;