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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Just to finish this thought, DW_AT_str_offsets_base is spec'd to point to the first entry for the unit, not the header, so the first contribution is at 8 or
16 depending on format (picky picky). That is, the entire section has only one header, rather than one header per compilation-unit or type-unit; you get one header + table per translation-unit. (Too many kinds of unit!) It seems not completely clear that
it would be a net savings to maintain separate string pools (or string-offset pools) per unit, so I don't know whether you'd really want str_offsets_base in .dwo units. Someone will have to run off and measure it at some point.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">--paulr<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> llvm-commits [mailto:llvm-commits-bounces@lists.llvm.org]
<b>On Behalf Of </b>David Blaikie via llvm-commits<br>
<b>Sent:</b> Thursday, June 29, 2017 2:51 PM<br>
<b>To:</b> reviews+D34765+public+e78f04ee01ee41e1@reviews.llvm.org; Pieb, Wolfgang; aprantl@apple.com<br>
<b>Cc:</b> llvm-commits@lists.llvm.org<br>
<b>Subject:</b> Re: [PATCH] D34765: [DWARF] [NFC] Move a couple of member functions to DWARFUnit (baseclass) from DWARFCompileUnit (derived class)<o:p></o:p></span></p>
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<p class="MsoNormal">On Thu, Jun 29, 2017 at 11:48 AM Paul Robinson via Phabricator <<a href="mailto:reviews@reviews.llvm.org">reviews@reviews.llvm.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">probinson added a comment.<br>
<br>
In <a href="https://reviews.llvm.org/D34765#795601" target="_blank">https://reviews.llvm.org/D34765#795601</a>, @wolfgangp wrote:<br>
<br>
> No you're right, my bad. Units in the .dwo sections (both type and CU) don't have a str_offsets_base, which implies that the .debug_str_offsets.dwo section has to consist of a monolithic table of string offsets (without the 8 or 16-byte header that's specified
in section 7.26 of the DWARF 5 standard). Section 7.26 seems to say the opposite, though. It seems I'll have to clarify this with the DWARF5 folks.<br>
<br>
<br>
Worth clarifying on the dwarf-discuss list but I believe the idea is that the .dwo would have a single .debug_str_offsets.dwo contribution (complete with header), corresponding to the .debug_str.dwo contribution, and all units in the compilation would share
it just like they would ordinarily share the single .debug_str section in a non-split compilation.<o:p></o:p></p>
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<p class="MsoNormal">Yeah, seems to me like DWO CUs basically get a "DW_AT_str_off_base" (or whatever it's called) should be assumed/implicit 0, but can be present (if a producer wants to put multiple separate str_off for separate CUs in a single DWO - for
example, to reduce the size of the str offsets (smaller numbers, shorter encoding, etc) in cases of many strings/many CUs, etc)<o:p></o:p></p>
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<br>
<a href="https://reviews.llvm.org/D34765" target="_blank">https://reviews.llvm.org/D34765</a><br>
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<o:p></o:p></p>
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