| Ying Wang | b9cc48a | 2013-09-20 16:17:43 -0700 | [diff] [blame] | 1 | <!doctype html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> |
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| 7 | <title>Optimizations</title> |
| Brian Carlstrom | 2270795 | 2015-01-08 08:24:06 -0800 | [diff] [blame] | 8 | </head> |
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| Joe Onorato | b72c5c2 | 2009-08-31 10:12:00 -0700 | [diff] [blame] | 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 | |
| Brian Carlstrom | 2270795 | 2015-01-08 08:24:06 -0800 | [diff] [blame] | 71 | <dt><code><b>class/unboxing/enum</b></code></dt> |
| 72 | <dd>Simplifies enum types to integer constants, whenever possible.</dd> |
| 73 | |
| Joe Onorato | b72c5c2 | 2009-08-31 10:12:00 -0700 | [diff] [blame] | 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 | |
| Ying Wang | b9cc48a | 2013-09-20 16:17:43 -0700 | [diff] [blame] | 143 | <dt><code><b>code/simplification/string</b></code></dt> |
| 144 | <dd>Performs peephole optimizations for constant strings.</dd> |
| 145 | |
| Joe Onorato | b72c5c2 | 2009-08-31 10:12:00 -0700 | [diff] [blame] | 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> |
| Ying Wang | b9cc48a | 2013-09-20 16:17:43 -0700 | [diff] [blame] | 164 | <dd>Removes exceptions with empty try blocks.</dd> |
| Joe Onorato | b72c5c2 | 2009-08-31 10:12:00 -0700 | [diff] [blame] | 165 | |
| 166 | <dt><code><b>code/allocation/variable</b></code></dt> |
| 167 | <dd>Optimizes variable allocation on the local variable frame.</dd> |
| 168 | </dl> |
| Ying Wang | 9f606f9 | 2012-02-27 18:34:24 -0800 | [diff] [blame] | 169 | <p> |
| Joe Onorato | b72c5c2 | 2009-08-31 10:12:00 -0700 | [diff] [blame] | 170 | |
| Ying Wang | b9cc48a | 2013-09-20 16:17:43 -0700 | [diff] [blame] | 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 /> |
| Joe Onorato | b72c5c2 | 2009-08-31 10:12:00 -0700 | [diff] [blame] | 197 | <address> |
| Brian Carlstrom | 2270795 | 2015-01-08 08:24:06 -0800 | [diff] [blame] | 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>. |
| Joe Onorato | b72c5c2 | 2009-08-31 10:12:00 -0700 | [diff] [blame] | 200 | </address> |
| 201 | </body> |
| 202 | </html> |
