1 Copyright (c) 2002, 2018, Oracle and/or its affiliates. All rights reserved. 2 DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 3 4 This code is free software; you can redistribute it and/or modify it 5 under the terms of the GNU General Public License version 2 only, as 6 published by the Free Software Foundation. 7 8 This code is distributed in the hope that it will be useful, but WITHOUT 9 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 version 2 for more details (a copy is included in the LICENSE file that 12 accompanied this code). 13 14 You should have received a copy of the GNU General Public License version 15 2 along with this work; if not, write to the Free Software Foundation, 16 Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 18 Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 19 or visit www.oracle.com if you need additional information or have any 20 questions. 21 22 Strength Reduction 23 ------------------ 24 25 Strength reduction replaces an expansive operation by a cheaper one, such as 26 multiplication by addition or subtraction, multiplication instead of 27 exponentiation; use compound assignment operators such as += wherever possible, 28 changing code of the form a[i] = a[i] + x to a[i] += x, since they result in 29 fewer bytecode instructions; use shifts instead of multiplication by powers of 30 two, etc. 31 32 For example: 33 34 x ** 2 = x * x 35 2.0 * x = x + x 36 x / 2 = x * 0.5 37 38 39 Induction Variable 40 ------------------ 41 42 A variable is called an induction variables of a loop if every time the variable 43 changes values it is incremented or decrmented by some constant. 44 Basic induction variables i whose only assignments within the loop is of the 45 form i += c, where c is a constant.