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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Aptos",sans-serif">Hi Mark,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Aptos",sans-serif">Both attached class listings are missing stack map frames at branch targets, and they seem to be invalid.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Aptos",sans-serif">I would like to ask what compiler generates the first class and how your tool adds the instrumentation code.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Aptos",sans-serif">My first impression is that I don’t see any trace of Class-File API stack map generator involment. Transformation of a method with missing or invalid stack map would generate
new stack maps, unless explicitly disabled.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Aptos",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Aptos",sans-serif">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Aptos",sans-serif">Adam<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Aptos",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Aptos",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">From:
</span></b><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">classfile-api-dev <classfile-api-dev-retn@openjdk.org> on behalf of Mark Roberts <markro@cs.washington.edu><br>
<b>Date: </b>Tuesday, 28 January 2025 at 21:45<br>
<b>To: </b>classfile-api-dev@openjdk.org <classfile-api-dev@openjdk.org><br>
<b>Cc: </b>Chen Liang <chen.l.liang@oracle.com><br>
<b>Subject: </b>StackMap problem<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">The existence of compiler generated, unnamed local temps (no LocalVariable code element) seems to cause a problem with stack maps.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">The ‘source’ attachment shows the problem method. The ‘before’ attachment shows the generated code before instrumentation. Note that the compiler generates an unnamed temp at slot 0 to store the exception
code. The stackmap for the branch target says same locals, which is correct.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">The ‘after’ attachment shows the code generated after our tool has added instrumentation code – note the addition of a new local variable at slot 1. The stackmap for the branch target still says same locals,
which is no longer correct. This causes the iload_1 @41 to fail.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I tried to see if this issue has already been reported, but I was unable to figure out how to search
</span><a href="https://bugs.java.com/bugdatabase/"><span style="font-size:11.0pt">https://bugs.java.com/bugdatabase/</span></a><span style="font-size:11.0pt"> by keyword.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Mark<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
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