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<p class="MsoNormal"><span style="font-family:"Aptos",sans-serif">Hi Mark,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Aptos",sans-serif">Code elements are generally not unique, so they cannot be used as keys in maps.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Aptos",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Aptos",sans-serif">However, there are several approaches to work around it (based on the use case):<o:p></o:p></span></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo4"><span style="font-family:"Aptos",sans-serif">If you need to iterate over a list of elements multiple times and then transform it – you can use the index of the element as a key.<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo4"><span style="font-family:"Aptos",sans-serif">Or if you have a complex set of chained and nested transformations and need to mark a code element for later identification, you can bind
a label (CodeBuilder::newBoundLabel) to a position before, after, or instead of the element. Labels are unique, and your subsequent transformations will receive a LabelTarget pseudo-instruction at the marked point, and LabelTarget::label will match the label
you bound earlier.<o:p></o:p></span></li></ul>
<p class="MsoNormal"><span style="font-family:"Aptos",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Aptos",sans-serif">Adam<o:p></o:p></span></p>
<p class="MsoNormal"><span style="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>Wednesday, 7 May 2025 at 21:06<br>
<b>To: </b>Chen Liang <chen.l.liang@oracle.com>, classfile-api-dev@openjdk.org <classfile-api-dev@openjdk.org><br>
<b>Subject: </b>RE: [External] : are CodeElements unique?<o:p></o:p></span></p>
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<p class="MsoNormal">How about only for the original, immutable elementlist prior to any transforms?<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Also, not sure what you meant by a (index, element) pair.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Thanks, Mark<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><b>From:</b> Chen Liang <<a href="mailto:chen.l.liang@oracle.com">chen.l.liang@oracle.com</a>>
<br>
<b>Sent:</b> Wednesday, May 7, 2025 11:03 AM<br>
<b>To:</b> Mark Roberts <<a href="mailto:markro@cs.washington.edu">markro@cs.washington.edu</a>>;
<a href="mailto:classfile-api-dev@openjdk.org">classfile-api-dev@openjdk.org</a><br>
<b>Subject:</b> Re: [External] : are CodeElements unique?<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Calibri Light",sans-serif;color:black">Hi Mark,</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Calibri Light",sans-serif;color:black">Very good question - and the answer is unfortunately, no. Transforms are allowed to reuse code models, and I think the bound Code attribute expansion also
returns duplicate load or store instructions.</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Calibri Light",sans-serif;color:black">To ensure identity, I think tracking a pair of (index, element) is better.</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Calibri Light",sans-serif;color:black"> </span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Calibri Light",sans-serif;color:black">Regards,</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Calibri Light",sans-serif;color:black">Chen Liang</span><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="color:black">From:</span></b><span style="color:black"> Mark Roberts <</span><a href="mailto:markro@cs.washington.edu">markro@cs.washington.edu</a><span style="color:black">><br>
<b>Sent:</b> Wednesday, May 7, 2025 12:43 PM<br>
<b>To:</b> </span><a href="mailto:classfile-api-dev@openjdk.org">classfile-api-dev@openjdk.org</a><span style="color:black"> <</span><a href="mailto:classfile-api-dev@openjdk.org">classfile-api-dev@openjdk.org</a><span style="color:black">><br>
<b>Cc:</b> Chen Liang <</span><a href="mailto:chen.l.liang@oracle.com">chen.l.liang@oracle.com</a><span style="color:black">><br>
<b>Subject:</b> [External] : are CodeElements unique?</span> <o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="xmsonormal">Are the members of a CodeModel.elementList() unique? Specifically, is it safe to use a CodeElement as the key value in a Map?<o:p></o:p></p>
<p class="xmsonormal"> <o:p></o:p></p>
<p class="xmsonormal">Thank you,<o:p></o:p></p>
<p class="xmsonormal">Mark<o:p></o:p></p>
<p class="xmsonormal"> <o:p></o:p></p>
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