jikesrvm.github.io/UserGuide/ClassLibraryInterface.html at master · JikesRVM/jikesrvm.github.io · GitHub

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<head><title>17 Interface to the Class Library</title>
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<h2 class="chapterHead"><span class="titlemark">Chapter 17</span><br /><a
 id="x20-25100017"></a>Interface to the Class Library</h2>
<!--l. 5--><p class="noindent" >The Jikes RVM currently only supports GNU Classpath. A long time ago, the Jikes
RVM also supported Apache Harmonoy. Support for OpenJDK/IcedTea is planned
but still far from usable.
</p><!--l. 7--><p class="noindent" >The description here focusses on the current state for GNU Classpath which deﬁnes
an explicit interface to the virtual machine implementation. Supporting OpenJDK
will require signiﬁcant changes to the interface to the class library. Those changes are
not described here.
</p>
<h3 class="sectionHead"><span class="titlemark">17.1   </span> <a
 id="x20-25200017.1"></a>Overview</h3>
<!--l. 11--><p class="noindent" >The current library interface is found in the directory <span class="obeylines-h"><span class="verb"><span
class="cmtt-10">libraryInterface</span></span></span>. It is
divided in the common parts that are necessary for all class libraryies and the
parts that diﬀer for each class library. The parts speciﬁc to the class library
are further grouped according to the licenses that apply to the respective
parts.
</p><!--l. 13--><p class="noindent" >The common parts include <span class="obeylines-h"><span class="verb"><span
class="cmtt-10">sun.misc.Unsafe</span></span></span> which is implemented via Jikes RVM
<a
href="/UserGuide/Magic/index.html#x18-21300015">Magic</a>.
</p><!--l. 17--><p class="noindent" >
</p>
<h3 class="sectionHead"><span class="titlemark">17.2   </span> <a
 id="x20-25300017.2"></a>GNU Classpath VM interface</h3>
<!--l. 19--><p class="noindent" >GNU Classpath deﬁnes certain classes that have to provided by the VM vendor.
Those classes are generally named VM*, e.g. <span class="obeylines-h"><span class="verb"><span
class="cmtt-10">VMString</span></span></span>, <span class="obeylines-h"><span class="verb"><span
class="cmtt-10">VMSystem</span></span></span>, <span class="obeylines-h"><span class="verb"><span
class="cmtt-10">VMThrowable</span></span></span>.
Implementations for those classes can be found at <br
class="newline" /><span class="obeylines-h"><span class="verb"><span
class="cmtt-10">libraryInterface/GNUClasspath/EPL/src</span></span></span>. GMU Classpath also provides
default versions for those classes. In some cases, the default versions are
used.
</p><!--l. 21--><p class="noindent" >Jikes RVM also directly replaces some classes from GNU Classpath with modiﬁed
versions. Those classes are found at <br
class="newline" /><span class="obeylines-h"><span class="verb"><span
class="cmtt-10">libraryInterface/GNUClasspath/LGPL/src</span></span></span>.
</p><!--l. 25--><p class="noindent" >
</p>
<h3 class="sectionHead"><span class="titlemark">17.3   </span> <a
 id="x20-25400017.3"></a>Naming conventions</h3>
<!--l. 27--><p class="noindent" >Classes that are named <span class="obeylines-h"><span class="verb"><span
class="cmtt-10">JikesRVMSupport</span></span></span> implement methods that Jikes RVM needs
to interact with the class library.
</p><!--l. 31--><p class="noindent" >
</p>
<h3 class="sectionHead"><span class="titlemark">17.4   </span> <a
 id="x20-25500017.4"></a>Build organisation</h3>


<!--l. 33--><p class="noindent" >The class library interface and the class library itself are compiled into a single jar
ﬁle, <span class="obeylines-h"><span class="verb"><span
class="cmtt-10">rvmrt.jar</span></span></span>. The classes from the <span class="obeylines-h"><span class="verb"><span
class="cmtt-10">libraryInterface</span></span></span> directory always have
priority over those from the class library. This allows replacement from classes from
the class library, e.g. for debugging.
</p><!--l. 35--><p class="noindent" >The build also has a step to add annotations to classes from the class library using ASM.
This is implemented by the class <span class="obeylines-h"><span class="verb"><span
class="cmtt-10">org.jikesrvm.tools.asm.AnnotationAdder</span></span></span>.


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