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Hi Fangrui,</div>
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> It is safe. The comment is about the references (isd->sections; script->orphanSections).<span></span></div>
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Thanks for the confirmation.</div>
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> <span>(I can fix it after one week if I haven't seen a patch yet:) )</span><br>
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I've posted a patch this morning.</div>
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<a href="https://reviews.llvm.org/D106427" id="LPlnk">https://reviews.llvm.org/D106427</a><br>
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Thank you,
<div>Amilendra<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Fangrui Song <maskray@google.com><br>
<b>Sent:</b> Wednesday, July 21, 2021 8:34 PM<br>
<b>To:</b> Amilendra Kodithuwakku <Amilendra.Kodithuwakku@arm.com><br>
<b>Cc:</b> llvm-dev <llvm-dev@lists.llvm.org><br>
<b>Subject:</b> Re: [llvm-dev] [lld][ELF] Regarding removeUnusedSyntheticSections()</font>
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On 2021-07-17, Amilendra Kodithuwakku via llvm-dev wrote:<br>
>Hi,<br>
><br>
>I am working on an LLD port for a research project based on the AARCH64 based architecture which requires adding a new SyntheticSection to InStruct, but doing so gives me 2 failed x86 tests:<br>
> lld :: ELF/shuffle-sections-init-fini.s<br>
> lld :: ELF/shuffle-sections.s<br>
>This new SyntheticSection is empty for X86, so in principle those tests should be unaffected.<br>
><br>
>The immediate reason is that the shuffle implementation, maybeShuffle(), is dependent on inputSections. I think the real cause is that removeUnusedSyntheticSections() does not remove empty sections from the inputSections vector (although there is a comment
that says that it does that). AFAICT elements are removed only from isd->sections and script->orphanSections.<br>
><br>
>I could not find any uses of empty sections after this point, but you never know so thought of asking here. Is there a reason empty SyntheticSections in inputSections is preserved after removeUnusedSyntheticSections()? Or is there another approach that will
not require maintaining the shuffle tests everytime a Synthetic section is added/removed?<br>
><br>
>If it is safe to remove empty SyntheticSections from inputSections I can send out a patch to do that. Locally I have a simple patch that confirms that the shuffle tests do not fail after adding a new SyntheticSection. I can't think of new regression tests
to add because this behavior cannot be demonstrated without adding a new SyntheticSection to InStruct.<br>
<br>
It is safe. The comment is about the references (isd->sections; script->orphanSections).<br>
<br>
(I can fix it after one week if I haven't seen a patch yet:) )<br>
<br>
>Thanks<br>
>Amilendra<br>
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