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<p class="MsoNormal"><span lang="EN-US">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Work on javap conversion from ASM to Classfile API and recent bug (<a href="https://bugs.openjdk.org/browse/JDK-8305990">JDK-8305990</a>) discovered in StripJavaDebugAttributesPlugin brought attention to missing JSR and
RET instructions support in Classfile API.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I’m proposing following changes to Classfile API:<o:p></o:p></span></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span lang="EN-US">Drop Opcode.Kind.UNSUPPORTED and add Opcode.Kind.DISCONTINUED_JSR and DISCONTINUED_RET<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span lang="EN-US">Add DiscontinuedInstruction interface with inner JsrInstruction and RetInstruction with standard factory methods<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span lang="EN-US">CodeImpl will parse and stream these instructions when present in the Code attribute<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span lang="EN-US">Do not add any new conveniency methods to CodeBuilder, the only way to build a code with these instructions will be cob.with(DiscontinuedInstruction. JsrInstruction.of(…))
and similar for RetInstruction<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span lang="EN-US">Fix DirectCodeBuilder so it invokes StackMapGenerator only for class file version >= 51.0 (BufWriterImpl must hold class version for that purpose)<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span lang="EN-US">Fix StackMapGenerator error message when these instruction appear in during generation<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span lang="EN-US">Implement fallback to jump target inflation in CodeImpl when the StackMapTable attribute is missing and class file version is < 51.0<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo2"><span lang="EN-US">Extend tests to verify JSR and RET instructions are correctly generated, transformed and reported as error (based on class file version).<o:p></o:p></span></li></ul>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Please review and comment this proposal under following pull request:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><a href="https://github.com/openjdk/jdk/pull/13478">https://github.com/openjdk/jdk/pull/13478</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Next step is to implement simple maxStack and maxLocals counter into DirectCodeBuilder for the cases where StackMapGenerator is not involved. Actual default to maxStack = maxLocals = 255 is not correct.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Adam<o:p></o:p></span></p>
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