third_party/java/proguard/proguard5.3.3/docs/manual/optimizations.html - bazel - Git at Google

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 <h2>Optimizations</h2>

 The optimization step of ProGuard can be switched off with the
 <a href="usage.html#dontoptimize"><code>-dontoptimize</code></a> option. For
 more fine-grained control over individual optimizations, experts can use the
 <a href="usage.html#optimizations"><code>-optimizations</code></a> option,
 with a filter based on the optimization names listed below. The filter works
 like any <a href="usage.html#filters">filter</a> in ProGuard.
 <p>

 The following wildcards are supported:

 <table cellspacing="10">
 <tr><td valign="top"><code><b>?</b></code></td>
     <td>matches any single character in an optimization name.</td></tr>
 <tr><td valign="top"><code><b>*</b></code></td>
     <td>matches any part of an optimization name.</td></tr>
 </table>

 An optimization that is preceded by an exclamation mark '<b>!</b>' is
 <i>excluded</i> from further attempts to match with <i>subsequent</i>
 optimization names in the filter. Make sure to specify filters correctly,
 since they are not checked for potential typos.
 <p>

 For example,
 "<code>code/simplification/variable,code/simplification/arithmetic</code>"
 only performs the two specified peephole optimizations.
 <p>

 For example, "<code>!method/propagation/*</code>" performs all optimizations,
 except the ones that propagate values between methods.
 <p>

 For example,
 "<code>!code/simplification/advanced,code/simplification/*</code>" only
 performs all peephole optimizations.
 <p>
 Some optimizations necessarily imply other optimizations. These are then
 indicated. Note that the list is likely to change over time, as optimizations
 are added and reorganized.
 <p>

 <dl>
 <dt><code><b>class/marking/final</b></code></dt>
 <dd>Marks classes as final, whenever possible.</dd>

 <dt><code><b>class/unboxing/enum</b></code></dt>
 <dd>Simplifies enum types to integer constants, whenever possible.</dd>

 <dt><code><b>class/merging/vertical</b></code></dt>
 <dd>Merges classes vertically in the class hierarchy, whenever possible.</dd>

 <dt><code><b>class/merging/horizontal</b></code></dt>
 <dd>Merges classes horizontally in the class hierarchy, whenever possible.</dd>

 <dt><div>(&rArr; <code>code/removal/advanced</code>)</div>
     <code><b>field/removal/writeonly</b></code></dt>
 <dd>Removes write-only fields.</dd>

 <dt><code><b>field/marking/private</b></code></dt>
 <dd>Marks fields as private, whenever possible.</dd>

 <dt><div>(&rArr; <code>code/simplification/advanced</code>)</div>
     <code><b>field/propagation/value</b></code></dt>
 <dd>Propagates the values of fields across methods.</dd>

 <dt><code><b>method/marking/private</b></code></dt>
 <dd>Marks methods as private, whenever possible (<i>devirtualization</i>).</dd>

 <dt><div>(&rArr; <code>code/removal/advanced</code>)</div>
     <code><b>method/marking/static</b></code></dt>
 <dd>Marks methods as static, whenever possible (<i>devirtualization</i>).</dd>

 <dt><code><b>method/marking/final</b></code></dt>
 <dd>Marks methods as final, whenever possible.</dd>

 <dt><div>(&rArr; <code>code/removal/advanced</code>)</div>
     <code><b>method/removal/parameter</b></code></dt>
 <dd>Removes unused method parameters.</dd>

 <dt><div>(&rArr; <code>code/simplification/advanced</code>)</div>
     <code><b>method/propagation/parameter</b></code></dt>
 <dd>Propagates the values of method parameters from method invocations to
     the invoked methods.</dd>

 <dt><div>(&rArr; <code>code/simplification/advanced</code>)</div>
     <code><b>method/propagation/returnvalue</b></code></dt>
 <dd>Propagates the values of method return values from methods to their
     invocations.</dd>

 <dt><code><b>method/inlining/short</b></code></dt>
 <dd>Inlines short methods.</dd>

 <dt><code><b>method/inlining/unique</b></code></dt>
 <dd>Inlines methods that are only called once.</dd>

 <dt><code><b>method/inlining/tailrecursion</b></code></dt>
 <dd>Simplifies tail recursion calls, whenever possible.</dd>

 <dt><code><b>code/merging</b></code></dt>
 <dd>Merges identical blocks of code by modifying branch targets.</dd>

 <dt><code><b>code/simplification/variable</b></code></dt>
 <dd>Performs peephole optimizations for variable loading and storing.</dd>

 <dt><code><b>code/simplification/arithmetic</b></code></dt>
 <dd>Performs peephole optimizations for arithmetic instructions.</dd>

 <dt><code><b>code/simplification/cast</b></code></dt>
 <dd>Performs peephole optimizations for casting operations.</dd>

 <dt><code><b>code/simplification/field</b></code></dt>
 <dd>Performs peephole optimizations for field loading and storing.</dd>

 <dt><div>(&rArr; <code>code/removal/simple</code>)</div>
     <code><b>code/simplification/branch</b></code></dt>
 <dd>Performs peephole optimizations for branch instructions.</dd>

 <dt><code><b>code/simplification/string</b></code></dt>
 <dd>Performs peephole optimizations for constant strings.</dd>

 <dt><div>(<i>best used with</i> <code>code/removal/advanced</code>)</div>
     <code><b>code/simplification/advanced</b></code></dt>
 <dd>Simplifies code based on control flow analysis and data flow
     analysis.</dd>

 <dt><div>(&rArr; <code>code/removal/exception</code>)</div>
     <code><b>code/removal/advanced</b></code></dt>
 <dd>Removes dead code based on control flow analysis and data flow
     analysis.</dd>

 <dt><div>(&rArr; <code>code/removal/exception</code>)</div>
     <code><b>code/removal/simple</b></code></dt>
 <dd>Removes dead code based on a simple control flow analysis.</dd>

 <dt><code><b>code/removal/variable</b></code></dt>
 <dd>Removes unused variables from the local variable frame.</dd>

 <dt><code><b>code/removal/exception</b></code></dt>
 <dd>Removes exceptions with empty try blocks.</dd>

 <dt><code><b>code/allocation/variable</b></code></dt>
 <dd>Optimizes variable allocation on the local variable frame.</dd>
 </dl>
 <p>

 ProGuard also provides some unofficial settings to control optimizations, that
 may disappear in future versions. These are Java system properties, which
 can be set as JVM arguments (with <code>-D.....)</code>:
 <dl>
 <dt><code><b>maximum.inlined.code.length</b></code> (default = 8 bytes)</dt>
 <dd>Specifies the maximum code length (expressed in bytes) of short methods
     that are eligible to be inlined. Inlining methods that are too long may
     unnecessarily inflate the code size.</dd>

 <dt><code><b>maximum.resulting.code.length</b></code> (default = 8000 bytes
     for JSE, 2000 bytes for JME)</dt>
 <dd>Specifies the maximum resulting code length (expressed in bytes) allowed
     when inlining methods. Many Java virtual machines do not apply just-in-time
     compilation to methods that are too long, so it's important not to let them
     grow too large.</dd>

 <dt><code><b>optimize.conservatively</b></code> (default = unset)</dt>
 <dd>Allows input code with ordinary instructions intentionally throwing
     <code>NullPointerException</code>,
     <code>ArrayIndexOutOfBoundsException</code>, or
     <code>ClassCastException</code>, without any other useful purposes. By
     default, ProGuard may just discard such seemingly useless instructions,
     resulting in better optimization of most common code.</dd>
 </dl>

 <hr />
 <address>
 Copyright &copy; 2002-2017
 <a target="other" href="http://www.lafortune.eu/">Eric Lafortune</a> @ <a target="top" href="http://www.guardsquare.com/">GuardSquare</a>.
 </address>
 </body>
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	<a class="largebutton" target="other" href="http://sourceforge.net/projects/proguard/">Sourceforge</a>
	</noscript>

	<h2>Optimizations</h2>

	The optimization step of ProGuard can be switched off with the
	<a href="usage.html#dontoptimize"><code>-dontoptimize</code></a> option. For
	more fine-grained control over individual optimizations, experts can use the
	<a href="usage.html#optimizations"><code>-optimizations</code></a> option,
	with a filter based on the optimization names listed below. The filter works
	like any <a href="usage.html#filters">filter</a> in ProGuard.
	<p>

	The following wildcards are supported:

	<table cellspacing="10">
	<tr><td valign="top"><code><b>?</b></code></td>
	<td>matches any single character in an optimization name.</td></tr>
	<tr><td valign="top"><code><b>*</b></code></td>
	<td>matches any part of an optimization name.</td></tr>
	</table>

	An optimization that is preceded by an exclamation mark '<b>!</b>' is
	<i>excluded</i> from further attempts to match with <i>subsequent</i>
	optimization names in the filter. Make sure to specify filters correctly,
	since they are not checked for potential typos.
	<p>

	For example,
	"<code>code/simplification/variable,code/simplification/arithmetic</code>"
	only performs the two specified peephole optimizations.
	<p>

	For example, "<code>!method/propagation/*</code>" performs all optimizations,
	except the ones that propagate values between methods.
	<p>

	For example,
	"<code>!code/simplification/advanced,code/simplification/*</code>" only
	performs all peephole optimizations.
	<p>
	Some optimizations necessarily imply other optimizations. These are then
	indicated. Note that the list is likely to change over time, as optimizations
	are added and reorganized.
	<p>

	<dl>
	<dt><code><b>class/marking/final</b></code></dt>
	<dd>Marks classes as final, whenever possible.</dd>

	<dt><code><b>class/unboxing/enum</b></code></dt>
	<dd>Simplifies enum types to integer constants, whenever possible.</dd>

	<dt><code><b>class/merging/vertical</b></code></dt>
	<dd>Merges classes vertically in the class hierarchy, whenever possible.</dd>

	<dt><code><b>class/merging/horizontal</b></code></dt>
	<dd>Merges classes horizontally in the class hierarchy, whenever possible.</dd>

	<dt><div>(⇒ <code>code/removal/advanced</code>)</div>
	<code><b>field/removal/writeonly</b></code></dt>
	<dd>Removes write-only fields.</dd>

	<dt><code><b>field/marking/private</b></code></dt>
	<dd>Marks fields as private, whenever possible.</dd>

	<dt><div>(⇒ <code>code/simplification/advanced</code>)</div>
	<code><b>field/propagation/value</b></code></dt>
	<dd>Propagates the values of fields across methods.</dd>

	<dt><code><b>method/marking/private</b></code></dt>
	<dd>Marks methods as private, whenever possible (<i>devirtualization</i>).</dd>

	<dt><div>(⇒ <code>code/removal/advanced</code>)</div>
	<code><b>method/marking/static</b></code></dt>
	<dd>Marks methods as static, whenever possible (<i>devirtualization</i>).</dd>

	<dt><code><b>method/marking/final</b></code></dt>
	<dd>Marks methods as final, whenever possible.</dd>

	<dt><div>(⇒ <code>code/removal/advanced</code>)</div>
	<code><b>method/removal/parameter</b></code></dt>
	<dd>Removes unused method parameters.</dd>

	<dt><div>(⇒ <code>code/simplification/advanced</code>)</div>
	<code><b>method/propagation/parameter</b></code></dt>
	<dd>Propagates the values of method parameters from method invocations to
	the invoked methods.</dd>

	<dt><div>(⇒ <code>code/simplification/advanced</code>)</div>
	<code><b>method/propagation/returnvalue</b></code></dt>
	<dd>Propagates the values of method return values from methods to their
	invocations.</dd>

	<dt><code><b>method/inlining/short</b></code></dt>
	<dd>Inlines short methods.</dd>

	<dt><code><b>method/inlining/unique</b></code></dt>
	<dd>Inlines methods that are only called once.</dd>

	<dt><code><b>method/inlining/tailrecursion</b></code></dt>
	<dd>Simplifies tail recursion calls, whenever possible.</dd>

	<dt><code><b>code/merging</b></code></dt>
	<dd>Merges identical blocks of code by modifying branch targets.</dd>

	<dt><code><b>code/simplification/variable</b></code></dt>
	<dd>Performs peephole optimizations for variable loading and storing.</dd>

	<dt><code><b>code/simplification/arithmetic</b></code></dt>
	<dd>Performs peephole optimizations for arithmetic instructions.</dd>

	<dt><code><b>code/simplification/cast</b></code></dt>
	<dd>Performs peephole optimizations for casting operations.</dd>

	<dt><code><b>code/simplification/field</b></code></dt>
	<dd>Performs peephole optimizations for field loading and storing.</dd>

	<dt><div>(⇒ <code>code/removal/simple</code>)</div>
	<code><b>code/simplification/branch</b></code></dt>
	<dd>Performs peephole optimizations for branch instructions.</dd>

	<dt><code><b>code/simplification/string</b></code></dt>
	<dd>Performs peephole optimizations for constant strings.</dd>

	<dt><div>(<i>best used with</i> <code>code/removal/advanced</code>)</div>
	<code><b>code/simplification/advanced</b></code></dt>
	<dd>Simplifies code based on control flow analysis and data flow
	analysis.</dd>

	<dt><div>(⇒ <code>code/removal/exception</code>)</div>
	<code><b>code/removal/advanced</b></code></dt>
	<dd>Removes dead code based on control flow analysis and data flow
	analysis.</dd>

	<dt><div>(⇒ <code>code/removal/exception</code>)</div>
	<code><b>code/removal/simple</b></code></dt>
	<dd>Removes dead code based on a simple control flow analysis.</dd>

	<dt><code><b>code/removal/variable</b></code></dt>
	<dd>Removes unused variables from the local variable frame.</dd>

	<dt><code><b>code/removal/exception</b></code></dt>
	<dd>Removes exceptions with empty try blocks.</dd>

	<dt><code><b>code/allocation/variable</b></code></dt>
	<dd>Optimizes variable allocation on the local variable frame.</dd>
	</dl>
	<p>

	ProGuard also provides some unofficial settings to control optimizations, that
	may disappear in future versions. These are Java system properties, which
	can be set as JVM arguments (with <code>-D.....)</code>:
	<dl>
	<dt><code><b>maximum.inlined.code.length</b></code> (default = 8 bytes)</dt>
	<dd>Specifies the maximum code length (expressed in bytes) of short methods
	that are eligible to be inlined. Inlining methods that are too long may
	unnecessarily inflate the code size.</dd>

	<dt><code><b>maximum.resulting.code.length</b></code> (default = 8000 bytes
	for JSE, 2000 bytes for JME)</dt>
	<dd>Specifies the maximum resulting code length (expressed in bytes) allowed
	when inlining methods. Many Java virtual machines do not apply just-in-time
	compilation to methods that are too long, so it's important not to let them
	grow too large.</dd>

	<dt><code><b>optimize.conservatively</b></code> (default = unset)</dt>
	<dd>Allows input code with ordinary instructions intentionally throwing
	<code>NullPointerException</code>,
	<code>ArrayIndexOutOfBoundsException</code>, or
	<code>ClassCastException</code>, without any other useful purposes. By
	default, ProGuard may just discard such seemingly useless instructions,
	resulting in better optimization of most common code.</dd>
	</dl>

	<hr />
	<address>
	Copyright © 2002-2017
	<a target="other" href="http://www.lafortune.eu/">Eric Lafortune</a> @ <a target="top" href="http://www.guardsquare.com/">GuardSquare</a>.
	</address>
	</body>
	</html>