From 40b1b2717827b5516c7d3978bdc341e801a650e7 Mon Sep 17 00:00:00 2001 From: Joost Vandevondele Date: Fri, 21 Oct 2016 06:48:07 +0200 Subject: [PATCH] Fix a series of undefined behaviours Avoid shifting negative signed integers and use typed enum to avoids decrementing a variable beyond its defined range, like: for (Rank r = RANK_8; r >= RANK_1; --r) Changes were tested individually and passed SPRT[-3, 1]. With this patch gcc --sanitize builds cleanly. No functional change. --- src/types.h | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/src/types.h b/src/types.h index 1bf42bbe..519f6af8 100644 --- a/src/types.h +++ b/src/types.h @@ -115,7 +115,7 @@ const int MAX_PLY = 128; /// any normal move destination square is always different from origin square /// while MOVE_NONE and MOVE_NULL have the same origin and destination square. -enum Move { +enum Move : int { MOVE_NONE, MOVE_NULL = 65 }; @@ -248,22 +248,23 @@ enum Square { NORTH_WEST = NORTH + WEST }; -enum File { +enum File : int { FILE_A, FILE_B, FILE_C, FILE_D, FILE_E, FILE_F, FILE_G, FILE_H, FILE_NB }; -enum Rank { +enum Rank : int { RANK_1, RANK_2, RANK_3, RANK_4, RANK_5, RANK_6, RANK_7, RANK_8, RANK_NB }; /// Score enum stores a middlegame and an endgame value in a single integer /// (enum). The least significant 16 bits are used to store the endgame value -/// and the upper 16 bits are used to store the middlegame value. +/// and the upper 16 bits are used to store the middlegame value. Take some +/// care to avoid left-shifting a signed int to avoid undefined behavior. enum Score : int { SCORE_ZERO }; inline Score make_score(int mg, int eg) { - return Score((eg << 16) + mg); + return Score((int)((unsigned int)eg << 16) + mg); } /// Extracting the signed lower and upper 16 bits is not so trivial because -- 2.39.2