MDEV-21981 Replace arithmetic + with bitwise OR when possible

Several macros such as sint2korr() and uint4korr() are using the
arithmetic + operator while a bitwise or operator would suffice.

GCC 5 and clang 5 and later can detect patterns consisting of
bitwise or and shifts by multiples of 8 bits, such as those used
in the InnoDB function mach_read_from_4(). They actually translate
that verbose low-level code into high-level machine language
(i486 bswap instruction or fused into the Haswell movbe instruction).

We should do the same for MariaDB Server code that is outside InnoDB.

Note: The Microsoft C compiler is lacking this optimization.
There, we might consider using _byteswap_ushort(), _byteswap_ulong(),
_byteswap_uint64(). But, those would lead to unaligned reads, which are
bad for reasons stated in MDEV-20277. Besides, outside InnoDB,
most data is already being stored in the native little-endian format
of that compiler.

include/byte_order_generic.h

 /* Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
+   Copyright (c) 2020, MariaDB Corporation.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -17,7 +18,7 @@
   Endianness-independent definitions for architectures other
   than the x86 architecture.
 */
-#define sint2korr(A)	(int16) (((int16) ((uchar) (A)[0])) +\
+#define sint2korr(A)	(int16) (((int16) ((uchar) (A)[0])) |\
 				 ((int16) ((int16) (A)[1]) << 8))
 #define sint3korr(A)	((int32) ((((uchar) (A)[2]) & 128) ? \
 				  (((uint32) 255L << 24) | \
@@ -27,38 +28,38 @@
 				  (((uint32) (uchar) (A)[2]) << 16) |\
 				  (((uint32) (uchar) (A)[1]) << 8) | \
 				  ((uint32) (uchar) (A)[0])))
-#define sint4korr(A)	(int32) (((int32) ((uchar) (A)[0])) +\
-				(((int32) ((uchar) (A)[1]) << 8)) +\
-				(((int32) ((uchar) (A)[2]) << 16)) +\
+#define sint4korr(A)	(int32) (((int32) ((uchar) (A)[0])) |\
+				(((int32) ((uchar) (A)[1]) << 8)) |\
+				(((int32) ((uchar) (A)[2]) << 16)) |\
 				(((int32) ((int16) (A)[3]) << 24)))
 #define sint8korr(A)	(longlong) uint8korr(A)
-#define uint2korr(A)	(uint16) (((uint16) ((uchar) (A)[0])) +\
+#define uint2korr(A)	(uint16) (((uint16) ((uchar) (A)[0])) |\
 				  ((uint16) ((uchar) (A)[1]) << 8))
-#define uint3korr(A)	(uint32) (((uint32) ((uchar) (A)[0])) +\
-				  (((uint32) ((uchar) (A)[1])) << 8) +\
+#define uint3korr(A)	(uint32) (((uint32) ((uchar) (A)[0])) |\
+				  (((uint32) ((uchar) (A)[1])) << 8) |\
 				  (((uint32) ((uchar) (A)[2])) << 16))
-#define uint4korr(A)	(uint32) (((uint32) ((uchar) (A)[0])) +\
-				  (((uint32) ((uchar) (A)[1])) << 8) +\
-				  (((uint32) ((uchar) (A)[2])) << 16) +\
+#define uint4korr(A)	(uint32) (((uint32) ((uchar) (A)[0])) |\
+				  (((uint32) ((uchar) (A)[1])) << 8) |\
+				  (((uint32) ((uchar) (A)[2])) << 16) |\
 				  (((uint32) ((uchar) (A)[3])) << 24))
-#define uint5korr(A)	((ulonglong)(((uint32) ((uchar) (A)[0])) +\
-				    (((uint32) ((uchar) (A)[1])) << 8) +\
-				    (((uint32) ((uchar) (A)[2])) << 16) +\
-				    (((uint32) ((uchar) (A)[3])) << 24)) +\
+#define uint5korr(A)	((ulonglong)(((uint32) ((uchar) (A)[0])) |\
+				    (((uint32) ((uchar) (A)[1])) << 8) |\
+				    (((uint32) ((uchar) (A)[2])) << 16) |\
+				    (((uint32) ((uchar) (A)[3])) << 24)) |\
 				    (((ulonglong) ((uchar) (A)[4])) << 32))
-#define uint6korr(A)	((ulonglong)(((uint32)    ((uchar) (A)[0]))          + \
-                                     (((uint32)    ((uchar) (A)[1])) << 8)   + \
-                                     (((uint32)    ((uchar) (A)[2])) << 16)  + \
-                                     (((uint32)    ((uchar) (A)[3])) << 24)) + \
-                         (((ulonglong) ((uchar) (A)[4])) << 32) +       \
+#define uint6korr(A)	((ulonglong)(((uint32)    ((uchar) (A)[0]))          | \
+                                     (((uint32)    ((uchar) (A)[1])) << 8)   | \
+                                     (((uint32)    ((uchar) (A)[2])) << 16)  | \
+                                     (((uint32)    ((uchar) (A)[3])) << 24)) | \
+                         (((ulonglong) ((uchar) (A)[4])) << 32) |       \
                          (((ulonglong) ((uchar) (A)[5])) << 40))
-#define uint8korr(A)	((ulonglong)(((uint32) ((uchar) (A)[0])) +\
-				    (((uint32) ((uchar) (A)[1])) << 8) +\
-				    (((uint32) ((uchar) (A)[2])) << 16) +\
-				    (((uint32) ((uchar) (A)[3])) << 24)) +\
-			(((ulonglong) (((uint32) ((uchar) (A)[4])) +\
-				    (((uint32) ((uchar) (A)[5])) << 8) +\
-				    (((uint32) ((uchar) (A)[6])) << 16) +\
+#define uint8korr(A)	((ulonglong)(((uint32) ((uchar) (A)[0])) |\
+				    (((uint32) ((uchar) (A)[1])) << 8) |\
+				    (((uint32) ((uchar) (A)[2])) << 16) |\
+				    (((uint32) ((uchar) (A)[3])) << 24)) |\
+			(((ulonglong) (((uint32) ((uchar) (A)[4])) |\
+				    (((uint32) ((uchar) (A)[5])) << 8) |\
+				    (((uint32) ((uchar) (A)[6])) << 16) |\
 				    (((uint32) ((uchar) (A)[7])) << 24))) <<\
 				    32))
 #define int2store(T,A)       do { uint def_temp= (uint) (A) ;\

include/byte_order_generic_x86.h

 /* Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
+   Copyright (c) 2020, MariaDB Corporation.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -27,20 +28,20 @@
 				  ((uint32) (uchar) (A)[0])))
 #define sint4korr(A)	(*((const long *) (A)))
 #define uint2korr(A)	(*((const uint16 *) (A)))
-#define uint3korr(A)	(uint32) (((uint32) ((uchar) (A)[0])) +\
-				  (((uint32) ((uchar) (A)[1])) << 8) +\
+#define uint3korr(A)	(uint32) (((uint32) ((uchar) (A)[0])) |\
+				  (((uint32) ((uchar) (A)[1])) << 8) |\
 				  (((uint32) ((uchar) (A)[2])) << 16))
 #define uint4korr(A)	(*((const uint32 *) (A)))
-#define uint5korr(A)	((ulonglong)(((uint32) ((uchar) (A)[0])) +\
-				    (((uint32) ((uchar) (A)[1])) << 8) +\
-				    (((uint32) ((uchar) (A)[2])) << 16) +\
-				    (((uint32) ((uchar) (A)[3])) << 24)) +\
+#define uint5korr(A)	((ulonglong)(((uint32) ((uchar) (A)[0])) |\
+				    (((uint32) ((uchar) (A)[1])) << 8) |\
+				    (((uint32) ((uchar) (A)[2])) << 16) |\
+				    (((uint32) ((uchar) (A)[3])) << 24)) |\
 				    (((ulonglong) ((uchar) (A)[4])) << 32))
-#define uint6korr(A)	((ulonglong)(((uint32)    ((uchar) (A)[0]))          + \
-                                     (((uint32)    ((uchar) (A)[1])) << 8)   + \
-                                     (((uint32)    ((uchar) (A)[2])) << 16)  + \
-                                     (((uint32)    ((uchar) (A)[3])) << 24)) + \
-                         (((ulonglong) ((uchar) (A)[4])) << 32) +       \
+#define uint6korr(A)	((ulonglong)(((uint32)    ((uchar) (A)[0]))          | \
+                                     (((uint32)    ((uchar) (A)[1])) << 8)   | \
+                                     (((uint32)    ((uchar) (A)[2])) << 16)  | \
+                                     (((uint32)    ((uchar) (A)[3])) << 24)) | \
+                         (((ulonglong) ((uchar) (A)[4])) << 32) |       \
                          (((ulonglong) ((uchar) (A)[5])) << 40))
 #define uint8korr(A)	(*((const ulonglong *) (A)))
 #define sint8korr(A)	(*((const longlong *) (A)))

include/byte_order_generic_x86_64.h

 /* Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
+   Copyright (c) 2020, MariaDB Corporation.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -28,8 +29,8 @@
 				  ((uint32) (uchar) (A)[0])))
 #define sint4korr(A)	(int32)  (*((int32 *) (A)))
 #define uint2korr(A)	(uint16) (*((uint16 *) (A)))
-#define uint3korr(A)	(uint32) (((uint32) ((uchar) (A)[0])) +\
-				  (((uint32) ((uchar) (A)[1])) << 8) +\
+#define uint3korr(A)	(uint32) (((uint32) ((uchar) (A)[0])) |\
+				  (((uint32) ((uchar) (A)[1])) << 8) |\
 				  (((uint32) ((uchar) (A)[2])) << 16))
 #define uint4korr(A)	(uint32) (*((uint32 *) (A)))
 
@@ -53,7 +54,7 @@ static inline ulonglong uint6korr(const void *p)
 #define int2store(T,A)	do { uchar *pT= (uchar*)(T);\
                              *((uint16*)(pT))= (uint16) (A);\
                         } while (0)
-  
+
 #define int3store(T,A)  do { *(T)=  (uchar) ((A));\
                             *(T+1)=(uchar) (((uint) (A) >> 8));\
                             *(T+2)=(uchar) (((A) >> 16));\

include/myisampack.h

@@ -2,6 +2,7 @@
 #define MYISAMPACK_INCLUDED
 
 /* Copyright (c) 2000-2002, 2004 MySQL AB, 2009 Sun Microsystems, Inc.
+   Copyright (c) 2020, MariaDB Corporation.
    Use is subject to license terms.
 
    This program is free software; you can redistribute it and/or modify
@@ -28,7 +29,7 @@
 #define mi_sint1korr(A) ((int8)(*A))
 #define mi_uint1korr(A) ((uint8)(*A))
 
-#define mi_sint2korr(A) ((int16) (((int16) (((const uchar*) (A))[1])) +\
+#define mi_sint2korr(A) ((int16) (((int16) (((const uchar*) (A))[1])) |\
                                   ((int16) ((int16) ((const char*) (A))[0]) << 8)))
 #define mi_sint3korr(A) ((int32) (((((const uchar*) (A))[0]) & 128) ? \
                                   (((uint32) 255L << 24) | \
@@ -38,58 +39,58 @@
                                   (((uint32) ((const uchar*) (A))[0]) << 16) |\
                                   (((uint32) ((const uchar*) (A))[1]) << 8) | \
                                   ((uint32) ((const uchar*) (A))[2])))
-#define mi_sint4korr(A) ((int32) (((int32) (((const uchar*) (A))[3])) +\
-                                  ((int32) (((const uchar*) (A))[2]) << 8) +\
-                                  ((int32) (((const uchar*) (A))[1]) << 16) +\
+#define mi_sint4korr(A) ((int32) (((int32) (((const uchar*) (A))[3])) |\
+                                  ((int32) (((const uchar*) (A))[2]) << 8) |\
+                                  ((int32) (((const uchar*) (A))[1]) << 16) |\
                                   ((int32) ((int16) ((const char*) (A))[0]) << 24)))
 #define mi_sint8korr(A) ((longlong) mi_uint8korr(A))
-#define mi_uint2korr(A) ((uint16) (((uint16) (((const uchar*) (A))[1])) +\
+#define mi_uint2korr(A) ((uint16) (((uint16) (((const uchar*) (A))[1])) |\
                                    ((uint16) (((const uchar*) (A))[0]) << 8)))
-#define mi_uint3korr(A) ((uint32) (((uint32) (((const uchar*) (A))[2])) +\
-                                   (((uint32) (((const uchar*) (A))[1])) << 8) +\
+#define mi_uint3korr(A) ((uint32) (((uint32) (((const uchar*) (A))[2])) |\
+                                   (((uint32) (((const uchar*) (A))[1])) << 8) |\
                                    (((uint32) (((const uchar*) (A))[0])) << 16)))
-#define mi_uint4korr(A) ((uint32) (((uint32) (((const uchar*) (A))[3])) +\
-                                   (((uint32) (((const uchar*) (A))[2])) << 8) +\
-                                   (((uint32) (((const uchar*) (A))[1])) << 16) +\
+#define mi_uint4korr(A) ((uint32) (((uint32) (((const uchar*) (A))[3])) |\
+                                   (((uint32) (((const uchar*) (A))[2])) << 8) |\
+                                   (((uint32) (((const uchar*) (A))[1])) << 16) |\
                                    (((uint32) (((const uchar*) (A))[0])) << 24)))
 
 #ifndef HAVE_mi_uint5korr
-#define mi_uint5korr(A) ((ulonglong)(((uint32) (((const uchar*) (A))[4])) +\
-                                    (((uint32) (((const uchar*) (A))[3])) << 8) +\
-                                    (((uint32) (((const uchar*) (A))[2])) << 16) +\
-                                    (((uint32) (((const uchar*) (A))[1])) << 24)) +\
+#define mi_uint5korr(A) ((ulonglong)(((uint32) (((const uchar*) (A))[4])) |\
+                                    (((uint32) (((const uchar*) (A))[3])) << 8) |\
+                                    (((uint32) (((const uchar*) (A))[2])) << 16) |\
+                                    (((uint32) (((const uchar*) (A))[1])) << 24)) |\
                                     (((ulonglong) (((const uchar*) (A))[0])) << 32))
 #endif /* HAVE_mi_uint5korr */
 
 #ifndef HAVE_mi_uint6korr
-#define mi_uint6korr(A) ((ulonglong)(((uint32) (((const uchar*) (A))[5])) +\
-                                    (((uint32) (((const uchar*) (A))[4])) << 8) +\
-                                    (((uint32) (((const uchar*) (A))[3])) << 16) +\
-                                    (((uint32) (((const uchar*) (A))[2])) << 24)) +\
-                        (((ulonglong) (((uint32) (((const uchar*) (A))[1])) +\
+#define mi_uint6korr(A) ((ulonglong)(((uint32) (((const uchar*) (A))[5])) |\
+                                    (((uint32) (((const uchar*) (A))[4])) << 8) |\
+                                    (((uint32) (((const uchar*) (A))[3])) << 16) |\
+                                    (((uint32) (((const uchar*) (A))[2])) << 24)) |\
+                        (((ulonglong) (((uint32) (((const uchar*) (A))[1])) |\
                                     (((uint32) (((const uchar*) (A))[0]) << 8)))) <<\
                                      32))
 #endif /* HAVE_mi_uint6korr */
 
 #ifndef HAVE_mi_uint7korr
-#define mi_uint7korr(A) ((ulonglong)(((uint32) (((const uchar*) (A))[6])) +\
-                                    (((uint32) (((const uchar*) (A))[5])) << 8) +\
-                                    (((uint32) (((const uchar*) (A))[4])) << 16) +\
-                                    (((uint32) (((const uchar*) (A))[3])) << 24)) +\
-                        (((ulonglong) (((uint32) (((const uchar*) (A))[2])) +\
-                                    (((uint32) (((const uchar*) (A))[1])) << 8) +\
+#define mi_uint7korr(A) ((ulonglong)(((uint32) (((const uchar*) (A))[6])) |\
+                                    (((uint32) (((const uchar*) (A))[5])) << 8) |\
+                                    (((uint32) (((const uchar*) (A))[4])) << 16) |\
+                                    (((uint32) (((const uchar*) (A))[3])) << 24)) |\
+                        (((ulonglong) (((uint32) (((const uchar*) (A))[2])) |\
+                                    (((uint32) (((const uchar*) (A))[1])) << 8) |\
                                     (((uint32) (((const uchar*) (A))[0])) << 16))) <<\
                                      32))
 #endif /* HAVE_mi_uint7korr */
 
 #ifndef HAVE_mi_uint8korr
-#define mi_uint8korr(A) ((ulonglong)(((uint32) (((const uchar*) (A))[7])) +\
-                                    (((uint32) (((const uchar*) (A))[6])) << 8) +\
-                                    (((uint32) (((const uchar*) (A))[5])) << 16) +\
-                                    (((uint32) (((const uchar*) (A))[4])) << 24)) +\
-                        (((ulonglong) (((uint32) (((const uchar*) (A))[3])) +\
-                                    (((uint32) (((const uchar*) (A))[2])) << 8) +\
-                                    (((uint32) (((const uchar*) (A))[1])) << 16) +\
+#define mi_uint8korr(A) ((ulonglong)(((uint32) (((const uchar*) (A))[7])) |\
+                                    (((uint32) (((const uchar*) (A))[6])) << 8) |\
+                                    (((uint32) (((const uchar*) (A))[5])) << 16) |\
+                                    (((uint32) (((const uchar*) (A))[4])) << 24)) |\
+                        (((ulonglong) (((uint32) (((const uchar*) (A))[3])) |\
+                                    (((uint32) (((const uchar*) (A))[2])) << 8) |\
+                                    (((uint32) (((const uchar*) (A))[1])) << 16) |\
                                     (((uint32) (((const uchar*) (A))[0])) << 24))) <<\
                                     32))
 #endif /* HAVE_mi_uint8korr */

storage/maria/ma_loghandler.c

 /* Copyright (C) 2007 MySQL AB & Sanja Belkin. 2010 Monty Program Ab.
+   Copyright (c) 2020, MariaDB Corporation.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -5440,15 +5441,15 @@ static uchar *translog_get_LSN_from_diff(LSN base_lsn, uchar *src, uchar *dst)
                           src + 1 + LSN_STORE_SIZE));
       DBUG_RETURN(src + 1 + LSN_STORE_SIZE);
     }
-    rec_offset= LSN_OFFSET(base_lsn) - ((first_byte << 8) + *((uint8*)src));
+    rec_offset= LSN_OFFSET(base_lsn) - ((first_byte << 8) | *((uint8*)src));
     break;
   case 1:
     diff= uint2korr(src);
-    rec_offset= LSN_OFFSET(base_lsn) - ((first_byte << 16) + diff);
+    rec_offset= LSN_OFFSET(base_lsn) - ((first_byte << 16) | diff);
     break;
   case 2:
     diff= uint3korr(src);
-    rec_offset= LSN_OFFSET(base_lsn) - ((first_byte << 24) + diff);
+    rec_offset= LSN_OFFSET(base_lsn) - ((first_byte << 24) | diff);
     break;
   case 3:
   {

storage/maria/ma_packrec.c

 /* Copyright (C) 2006 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
+   Copyright (c) 2020, MariaDB Corporation.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -1157,10 +1158,10 @@ static void decode_bytes(MARIA_COLUMNDEF *rec,MARIA_BIT_BUFF *bit_buff,
 	bit_buff->error=1;
 	return;				/* Can't be right */
       }
-      bit_buff->current_byte= (bit_buff->current_byte << 32) +
-	((((uint) bit_buff->pos[3])) +
-	 (((uint) bit_buff->pos[2]) << 8) +
-	 (((uint) bit_buff->pos[1]) << 16) +
+      bit_buff->current_byte= (bit_buff->current_byte << 32) |
+	((((uint) bit_buff->pos[3])) |
+	 (((uint) bit_buff->pos[2]) << 8) |
+	 (((uint) bit_buff->pos[1]) << 16) |
 	 (((uint) bit_buff->pos[0]) << 24));
       bit_buff->pos+=4;
       bits+=32;
@@ -1251,23 +1252,23 @@ static void decode_bytes(MARIA_COLUMNDEF *rec, MARIA_BIT_BUFF *bit_buff,
 	return;				/* Can't be right */
       }
 #if BITS_SAVED == 32
-      bit_buff->current_byte= (bit_buff->current_byte << 24) +
-	(((uint) ((uchar) bit_buff->pos[2]))) +
-	  (((uint) ((uchar) bit_buff->pos[1])) << 8) +
+      bit_buff->current_byte= (bit_buff->current_byte << 24) |
+	(((uint) ((uchar) bit_buff->pos[2]))) |
+	  (((uint) ((uchar) bit_buff->pos[1])) << 8) |
 	    (((uint) ((uchar) bit_buff->pos[0])) << 16);
       bit_buff->pos+=3;
       bits+=24;
 #else
       if (bits)				/* We must have at leasts 9 bits */
       {
-	bit_buff->current_byte=  (bit_buff->current_byte << 8) +
+	bit_buff->current_byte=  (bit_buff->current_byte << 8) |
 	  (uint) ((uchar) bit_buff->pos[0]);
 	bit_buff->pos++;
 	bits+=8;
       }
       else
       {
-	bit_buff->current_byte= ((uint) ((uchar) bit_buff->pos[0]) << 8) +
+	bit_buff->current_byte= ((uint) ((uchar) bit_buff->pos[0]) << 8) |
 	  ((uint) ((uchar) bit_buff->pos[1]));
 	bit_buff->pos+=2;
 	bits+=16;
@@ -1291,14 +1292,14 @@ static void decode_bytes(MARIA_COLUMNDEF *rec, MARIA_BIT_BUFF *bit_buff,
 	if (bits < 8)
 	{				/* We don't need to check end */
 #if BITS_SAVED == 32
-	  bit_buff->current_byte= (bit_buff->current_byte << 24) +
-	    (((uint) ((uchar) bit_buff->pos[2]))) +
-	      (((uint) ((uchar) bit_buff->pos[1])) << 8) +
+	  bit_buff->current_byte= (bit_buff->current_byte << 24) |
+	    (((uint) ((uchar) bit_buff->pos[2]))) |
+	      (((uint) ((uchar) bit_buff->pos[1])) << 8) |
 		(((uint) ((uchar) bit_buff->pos[0])) << 16);
 	  bit_buff->pos+=3;
 	  bits+=24;
 #else
-	  bit_buff->current_byte=  (bit_buff->current_byte << 8) +
+	  bit_buff->current_byte=  (bit_buff->current_byte << 8) |
 	    (uint) ((uchar) bit_buff->pos[0]);
 	  bit_buff->pos+=1;
 	  bits+=8;
@@ -1488,25 +1489,25 @@ static void fill_buffer(MARIA_BIT_BUFF *bit_buff)
     return;
   }
 #if BITS_SAVED == 64
-  bit_buff->current_byte=  ((((uint) ((uchar) bit_buff->pos[7]))) +
-			     (((uint) ((uchar) bit_buff->pos[6])) << 8) +
-			     (((uint) ((uchar) bit_buff->pos[5])) << 16) +
-			     (((uint) ((uchar) bit_buff->pos[4])) << 24) +
+  bit_buff->current_byte=  ((((uint) ((uchar) bit_buff->pos[7]))) |
+			     (((uint) ((uchar) bit_buff->pos[6])) << 8) |
+			     (((uint) ((uchar) bit_buff->pos[5])) << 16) |
+			     (((uint) ((uchar) bit_buff->pos[4])) << 24) |
 			     ((ulonglong)
-			      ((((uint) ((uchar) bit_buff->pos[3]))) +
-			       (((uint) ((uchar) bit_buff->pos[2])) << 8) +
-			       (((uint) ((uchar) bit_buff->pos[1])) << 16) +
+			      ((((uint) ((uchar) bit_buff->pos[3]))) |
+			       (((uint) ((uchar) bit_buff->pos[2])) << 8) |
+			       (((uint) ((uchar) bit_buff->pos[1])) << 16) |
 			       (((uint) ((uchar) bit_buff->pos[0])) << 24)) << 32));
   bit_buff->pos+=8;
 #else
 #if BITS_SAVED == 32
-  bit_buff->current_byte=  (((uint) ((uchar) bit_buff->pos[3])) +
-			     (((uint) ((uchar) bit_buff->pos[2])) << 8) +
-			     (((uint) ((uchar) bit_buff->pos[1])) << 16) +
+  bit_buff->current_byte=  (((uint) ((uchar) bit_buff->pos[3])) |
+			     (((uint) ((uchar) bit_buff->pos[2])) << 8) |
+			     (((uint) ((uchar) bit_buff->pos[1])) << 16) |
 			     (((uint) ((uchar) bit_buff->pos[0])) << 24));
   bit_buff->pos+=4;
 #else
-  bit_buff->current_byte=  (uint) (((uint) ((uchar) bit_buff->pos[1]))+
+  bit_buff->current_byte=  (uint) (((uint) ((uchar) bit_buff->pos[1])) |
 				    (((uint) ((uchar) bit_buff->pos[0])) << 8));
   bit_buff->pos+=2;
 #endif

storage/myisam/mi_packrec.c

 /* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
+   Copyright (c) 2020, MariaDB Corporation.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -1111,10 +1112,10 @@ static void decode_bytes(MI_COLUMNDEF *rec,MI_BIT_BUFF *bit_buff,uchar *to,
 	bit_buff->error=1;
 	return;				/* Can't be right */
       }
-      bit_buff->current_byte= (bit_buff->current_byte << 32) +
-	((((uint) bit_buff->pos[3])) +
-	 (((uint) bit_buff->pos[2]) << 8) +
-	 (((uint) bit_buff->pos[1]) << 16) +
+      bit_buff->current_byte= (bit_buff->current_byte << 32) |
+	((((uint) bit_buff->pos[3])) |
+	 (((uint) bit_buff->pos[2]) << 8) |
+	 (((uint) bit_buff->pos[1]) << 16) |
 	 (((uint) bit_buff->pos[0]) << 24));
       bit_buff->pos+=4;
       bits+=32;
@@ -1205,23 +1206,23 @@ static void decode_bytes(MI_COLUMNDEF *rec, MI_BIT_BUFF *bit_buff, uchar *to,
 	return;				/* Can't be right */
       }
 #if BITS_SAVED == 32
-      bit_buff->current_byte= (bit_buff->current_byte << 24) +
-	(((uint) ((uchar) bit_buff->pos[2]))) +
-	  (((uint) ((uchar) bit_buff->pos[1])) << 8) +
+      bit_buff->current_byte= (bit_buff->current_byte << 24) |
+	(((uint) ((uchar) bit_buff->pos[2]))) |
+	  (((uint) ((uchar) bit_buff->pos[1])) << 8) |
 	    (((uint) ((uchar) bit_buff->pos[0])) << 16);
       bit_buff->pos+=3;
       bits+=24;
 #else
       if (bits)				/* We must have at leasts 9 bits */
       {
-	bit_buff->current_byte=  (bit_buff->current_byte << 8) +
+	bit_buff->current_byte=  (bit_buff->current_byte << 8) |
 	  (uint) ((uchar) bit_buff->pos[0]);
 	bit_buff->pos++;
 	bits+=8;
       }
       else
       {
-	bit_buff->current_byte= ((uint) ((uchar) bit_buff->pos[0]) << 8) +
+	bit_buff->current_byte= ((uint) ((uchar) bit_buff->pos[0]) << 8) |
 	  ((uint) ((uchar) bit_buff->pos[1]));
 	bit_buff->pos+=2;
 	bits+=16;
@@ -1245,14 +1246,14 @@ static void decode_bytes(MI_COLUMNDEF *rec, MI_BIT_BUFF *bit_buff, uchar *to,
 	if (bits < 8)
 	{				/* We don't need to check end */
 #if BITS_SAVED == 32
-	  bit_buff->current_byte= (bit_buff->current_byte << 24) +
-	    (((uint) ((uchar) bit_buff->pos[2]))) +
-	      (((uint) ((uchar) bit_buff->pos[1])) << 8) +
+	  bit_buff->current_byte= (bit_buff->current_byte << 24) |
+	    (((uint) ((uchar) bit_buff->pos[2]))) |
+	      (((uint) ((uchar) bit_buff->pos[1])) << 8) |
 		(((uint) ((uchar) bit_buff->pos[0])) << 16);
 	  bit_buff->pos+=3;
 	  bits+=24;
 #else
-	  bit_buff->current_byte=  (bit_buff->current_byte << 8) +
+	  bit_buff->current_byte=  (bit_buff->current_byte << 8) |
 	    (uint) ((uchar) bit_buff->pos[0]);
 	  bit_buff->pos+=1;
 	  bits+=8;
@@ -1439,25 +1440,25 @@ static void fill_buffer(MI_BIT_BUFF *bit_buff)
   }
 
 #if BITS_SAVED == 64
-  bit_buff->current_byte=  ((((uint) ((uchar) bit_buff->pos[7]))) +
-			     (((uint) ((uchar) bit_buff->pos[6])) << 8) +
-			     (((uint) ((uchar) bit_buff->pos[5])) << 16) +
-			     (((uint) ((uchar) bit_buff->pos[4])) << 24) +
+  bit_buff->current_byte=  ((((uint) ((uchar) bit_buff->pos[7]))) |
+			     (((uint) ((uchar) bit_buff->pos[6])) << 8) |
+			     (((uint) ((uchar) bit_buff->pos[5])) << 16) |
+			     (((uint) ((uchar) bit_buff->pos[4])) << 24) |
 			     ((ulonglong)
-			      ((((uint) ((uchar) bit_buff->pos[3]))) +
-			       (((uint) ((uchar) bit_buff->pos[2])) << 8) +
-			       (((uint) ((uchar) bit_buff->pos[1])) << 16) +
+			      ((((uint) ((uchar) bit_buff->pos[3]))) |
+			       (((uint) ((uchar) bit_buff->pos[2])) << 8) |
+			       (((uint) ((uchar) bit_buff->pos[1])) << 16) |
 			       (((uint) ((uchar) bit_buff->pos[0])) << 24)) << 32));
   bit_buff->pos+=8;
 #else
 #if BITS_SAVED == 32
-  bit_buff->current_byte=  (((uint) ((uchar) bit_buff->pos[3])) +
-			     (((uint) ((uchar) bit_buff->pos[2])) << 8) +
-			     (((uint) ((uchar) bit_buff->pos[1])) << 16) +
+  bit_buff->current_byte=  (((uint) ((uchar) bit_buff->pos[3])) |
+			     (((uint) ((uchar) bit_buff->pos[2])) << 8) |
+			     (((uint) ((uchar) bit_buff->pos[1])) << 16) |
 			     (((uint) ((uchar) bit_buff->pos[0])) << 24));
   bit_buff->pos+=4;
 #else
-  bit_buff->current_byte=  (uint) (((uint) ((uchar) bit_buff->pos[1]))+
+  bit_buff->current_byte=  (uint) (((uint) ((uchar) bit_buff->pos[1])) |
 				    (((uint) ((uchar) bit_buff->pos[0])) << 8));
   bit_buff->pos+=2;
 #endif