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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hi Ali,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Soot cannot know the type of the variable, because Java bytecode does not contain types for local variables. Consequently, the type inference algorithm deduces
a NULL_TYPE, which essentially means “all we know is that this is an object that is always null”. The callgraph algorithm cannot really do anything useful with a NULL_TYPE, and consequently, we transform it into an explicit exception.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> Steven<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Soot-list <soot-list-bounces@cs.mcgill.ca>
<b>On Behalf Of </b>Ali Ghanbari<br>
<b>Sent:</b> Sunday, March 25, 2018 5:05 AM<br>
<b>To:</b> soot-list@cs.mcgill.ca<br>
<b>Subject:</b> [Soot-list] Unwanted Transformation? Analyzing Library Code?<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Hi,<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">I want to analyze a program which does not have
<i>single</i> entry point (i.e. it is a library). The code base, instead, does have a set of test cases.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">I built a program using ASM to construct a "mock" main function from those test cases. My program produced statements like the following:<br>
<br>
org.apache.commons.math4.exception.NumberIsTooSmallExceptionTest obj0 = null;<br>
obj0.testAccessors();<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">I thought that as long as the type of obj0 is known, Soot won't have any problem for doing CHA (and doing the rest of whole-program analyses). Unfortunately, I noticed that Soot does some unwanted optimization!
I found the following in the .jimple file produced by Soot for my mock main (all other calls to client code were removed!):<br>
<br>
r8 = new java.lang.NullPointerException;<br>
specialinvoke r8.<java.lang.NullPointerException: void <init>(java.lang.String)>("This statement would have triggered an Exception: virtualinvoke obj0.<org.apache.commons.math4.exception.NumberIsTooSmallExceptionTest: void testAccessors()>()");<br>
throw r8;<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">It is very intelligent that Soot can detect that, but (for now) I don't want such transformations!<o:p></o:p></p>
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<p class="MsoNormal">I would appreciate if you answer the my questions:<br>
<br>
1. Is that possible to instruct Soot to analyze the library based on the test cases? I mean without the need for any mock main method to be constructed?<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><br>
2. Does anyone know how can I avoid this unwanted transformation? Who does that transformation Java compiler or Soot?<br>
<br>
<o:p></o:p></p>
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<p class="MsoNormal">Thank you so much<o:p></o:p></p>
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