1 <!doctype html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2 <html> 3 <head> 4 <meta http-equiv="content-type" content="text/html; charset=iso-8859-1"> 5 <meta http-equiv="content-style-type" content="text/css"> 6 <link rel="stylesheet" type="text/css" href="style.css"> 7 <title>Optimizations</title> 8 </head> 9 <body> 10 11 <script type="text/javascript" language="JavaScript"> 12 <!-- 13 if (window.self==window.top) 14 document.write('<a class="largebutton" target="_top" href="../index.html#manual/optimizations.html">ProGuard index</a> <a class="largebutton" target="_top" href="http://www.saikoa.com/dexguard">DexGuard</a> <a class="largebutton" target="_top" href="http://www.saikoa.com/">Saikoa</a> <a class="largebutton" target="other" href="http://sourceforge.net/projects/proguard/">Sourceforge</a>') 15 //--> 16 </script> 17 <noscript> 18 <a class="largebutton" target="_top" href="../index.html#manual/optimizations.html">ProGuard index</a> 19 <a class="largebutton" target="_top" href="http://www.saikoa.com/dexguard">DexGuard</a> 20 <a class="largebutton" target="_top" href="http://www.saikoa.com/">Saikoa</a> 21 <a class="largebutton" target="other" href="http://sourceforge.net/projects/proguard/">Sourceforge</a> 22 </noscript> 23 24 <h2>Optimizations</h2> 25 26 The optimization step of ProGuard can be switched off with the 27 <a href="usage.html#dontoptimize"><code>-dontoptimize</code></a> option. For 28 more fine-grained control over individual optimizations, experts can use the 29 <a href="usage.html#optimizations"><code>-optimizations</code></a> option, 30 with a filter based on the optimization names listed below. The filter works 31 like any <a href="usage.html#filters">filter</a> in ProGuard. 32 <p> 33 34 The following wildcards are supported: 35 36 <table cellspacing="10"> 37 <tr><td valign="top"><code><b>?</b></code></td> 38 <td>matches any single character in an optimization name.</td></tr> 39 <tr><td valign="top"><code><b>*</b></code></td> 40 <td>matches any part of an optimization name.</td></tr> 41 </table> 42 43 An optimization that is preceded by an exclamation mark '<b>!</b>' is 44 <i>excluded</i> from further attempts to match with <i>subsequent</i> 45 optimization names in the filter. Make sure to specify filters correctly, 46 since they are not checked for potential typos. 47 <p> 48 49 For example, 50 "<code>code/simplification/variable,code/simplification/arithmetic</code>" 51 only performs the two specified peephole optimizations. 52 <p> 53 54 For example, "<code>!method/propagation/*</code>" performs all optimizations, 55 except the ones that propagate values between methods. 56 <p> 57 58 For example, 59 "<code>!code/simplification/advanced,code/simplification/*</code>" only 60 performs all peephole optimizations. 61 <p> 62 Some optimizations necessarily imply other optimizations. These are then 63 indicated. Note that the list is likely to change over time, as optimizations 64 are added and reorganized. 65 <p> 66 67 <dl> 68 <dt><code><b>class/marking/final</b></code></dt> 69 <dd>Marks classes as final, whenever possible.</dd> 70 71 <dt><code><b>class/unboxing/enum</b></code></dt> 72 <dd>Simplifies enum types to integer constants, whenever possible.</dd> 73 74 <dt><code><b>class/merging/vertical</b></code></dt> 75 <dd>Merges classes vertically in the class hierarchy, whenever possible.</dd> 76 77 <dt><code><b>class/merging/horizontal</b></code></dt> 78 <dd>Merges classes horizontally in the class hierarchy, whenever possible.</dd> 79 80 <dt><div>(⇒ <code>code/removal/advanced</code>)</div> 81 <code><b>field/removal/writeonly</b></code></dt> 82 <dd>Removes write-only fields.</dd> 83 84 <dt><code><b>field/marking/private</b></code></dt> 85 <dd>Marks fields as private, whenever possible.</dd> 86 87 <dt><div>(⇒ <code>code/simplification/advanced</code>)</div> 88 <code><b>field/propagation/value</b></code></dt> 89 <dd>Propagates the values of fields across methods.</dd> 90 91 <dt><code><b>method/marking/private</b></code></dt> 92 <dd>Marks methods as private, whenever possible (<i>devirtualization</i>).</dd> 93 94 <dt><div>(⇒ <code>code/removal/advanced</code>)</div> 95 <code><b>method/marking/static</b></code></dt> 96 <dd>Marks methods as static, whenever possible (<i>devirtualization</i>).</dd> 97 98 <dt><code><b>method/marking/final</b></code></dt> 99 <dd>Marks methods as final, whenever possible.</dd> 100 101 <dt><div>(⇒ <code>code/removal/advanced</code>)</div> 102 <code><b>method/removal/parameter</b></code></dt> 103 <dd>Removes unused method parameters.</dd> 104 105 <dt><div>(⇒ <code>code/simplification/advanced</code>)</div> 106 <code><b>method/propagation/parameter</b></code></dt> 107 <dd>Propagates the values of method parameters from method invocations to 108 the invoked methods.</dd> 109 110 <dt><div>(⇒ <code>code/simplification/advanced</code>)</div> 111 <code><b>method/propagation/returnvalue</b></code></dt> 112 <dd>Propagates the values of method return values from methods to their 113 invocations.</dd> 114 115 <dt><code><b>method/inlining/short</b></code></dt> 116 <dd>Inlines short methods.</dd> 117 118 <dt><code><b>method/inlining/unique</b></code></dt> 119 <dd>Inlines methods that are only called once.</dd> 120 121 <dt><code><b>method/inlining/tailrecursion</b></code></dt> 122 <dd>Simplifies tail recursion calls, whenever possible.</dd> 123 124 <dt><code><b>code/merging</b></code></dt> 125 <dd>Merges identical blocks of code by modifying branch targets.</dd> 126 127 <dt><code><b>code/simplification/variable</b></code></dt> 128 <dd>Performs peephole optimizations for variable loading and storing.</dd> 129 130 <dt><code><b>code/simplification/arithmetic</b></code></dt> 131 <dd>Performs peephole optimizations for arithmetic instructions.</dd> 132 133 <dt><code><b>code/simplification/cast</b></code></dt> 134 <dd>Performs peephole optimizations for casting operations.</dd> 135 136 <dt><code><b>code/simplification/field</b></code></dt> 137 <dd>Performs peephole optimizations for field loading and storing.</dd> 138 139 <dt><div>(⇒ <code>code/removal/simple</code>)</div> 140 <code><b>code/simplification/branch</b></code></dt> 141 <dd>Performs peephole optimizations for branch instructions.</dd> 142 143 <dt><code><b>code/simplification/string</b></code></dt> 144 <dd>Performs peephole optimizations for constant strings.</dd> 145 146 <dt><div>(<i>best used with</i> <code>code/removal/advanced</code>)</div> 147 <code><b>code/simplification/advanced</b></code></dt> 148 <dd>Simplifies code based on control flow analysis and data flow 149 analysis.</dd> 150 151 <dt><div>(⇒ <code>code/removal/exception</code>)</div> 152 <code><b>code/removal/advanced</b></code></dt> 153 <dd>Removes dead code based on control flow analysis and data flow 154 analysis.</dd> 155 156 <dt><div>(⇒ <code>code/removal/exception</code>)</div> 157 <code><b>code/removal/simple</b></code></dt> 158 <dd>Removes dead code based on a simple control flow analysis.</dd> 159 160 <dt><code><b>code/removal/variable</b></code></dt> 161 <dd>Removes unused variables from the local variable frame.</dd> 162 163 <dt><code><b>code/removal/exception</b></code></dt> 164 <dd>Removes exceptions with empty try blocks.</dd> 165 166 <dt><code><b>code/allocation/variable</b></code></dt> 167 <dd>Optimizes variable allocation on the local variable frame.</dd> 168 </dl> 169 <p> 170 171 ProGuard also provides some unofficial settings to control optimizations, that 172 may disappear in future versions. These are Java system properties, which 173 can be set as JVM arguments (with <code>-D.....)</code>: 174 <dl> 175 <dt><code><b>maximum.inlined.code.length</b></code> (default = 8 bytes)</dt> 176 <dd>Specifies the maximum code length (expressed in bytes) of short methods 177 that are eligible to be inlined. Inlining methods that are too long may 178 unnecessarily inflate the code size.</dd> 179 180 <dt><code><b>maximum.resulting.code.length</b></code> (default = 8000 bytes 181 for JSE, 2000 bytes for JME)</dt> 182 <dd>Specifies the maximum resulting code length (expressed in bytes) allowed 183 when inlining methods. Many Java virtual machines do not apply just-in-time 184 compilation to methods that are too long, so it's important not to let them 185 grow too large.</dd> 186 187 <dt><code><b>optimize.conservatively</b></code> (default = unset)</dt> 188 <dd>Allows input code with ordinary instructions intentionally throwing 189 <code>NullPointerException</code>, 190 <code>ArrayIndexOutOfBoundsException</code>, or 191 <code>ClassCastException</code>, without any other useful purposes. By 192 default, ProGuard may just discard such seemingly useless instructions, 193 resulting in better optimization of most common code.</dd> 194 </dl> 195 196 <hr /> 197 <address> 198 Copyright © 2002-2014 199 <a target="other" href="http://www.lafortune.eu/">Eric Lafortune</a> @ <a target="top" href="http://www.saikoa.com/">Saikoa</a>. 200 </address> 201 </body> 202 </html> 203