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<p class="MsoNormal"><span style="font-size:11.0pt">The spec does say they occur in the same order, which strongly implies that there is a DW_TAG_call_site_parameter for each actual parameter. Although, now that I say that, I have a memory of some discussion
where a parameter entry might be omitted entirely. I don’t remember the details, but Jakub probably does. The spec does not clearly say that parameter entries can be omitted, though.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">--paulr<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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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Sergey <spevnev16@gmail.com>
<br>
<b>Sent:</b> Friday, June 14, 2024 1:12 PM<br>
<b>To:</b> dwarf-discuss@lists.dwarfstd.org; Robinson, Paul <paul.robinson@sony.com><br>
<b>Subject:</b> RE: [Dwarf-discuss] Request for clarification of handling stack-passed parameters<o:p></o:p></span></p>
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<p class="MsoNormal">In that case I shall create appropriate issues for the mentioned compilers in order to discuss the matter with them.<br>
<br>
I think I have found another issue with clang. In some cases it does not generate middle parameters: namely, it skipped the 2nd one yet included the 3rd one.<br>
It believe it does not match the standard (p91 line 6-7): "Call site parameter entries occur in the same order as the corresponding parameters in the source.", does it?<o:p></o:p></p>
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<p class="MsoNormal">On Jun 14, 2024, 15:11 +0300, Robinson, Paul <<a href="mailto:paul.robinson@sony.com">paul.robinson@sony.com</a>>, wrote:<br>
<br>
<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt">I believe this is an issue with the implementations, although it is a bit odd that both gcc and clang behave the same way. There should be a DW_TAG_call_site_parameter
for each parameter. DW_AT_location should describe the stack slot where the parameter is passed. It should not be a problem for the compiler to do that, the location description would be evaluated in the context of the caller.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt">--paulr</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b>
<span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Dwarf-discuss <<a href="mailto:dwarf-discuss-bounces+paul.robinson=sony.com@lists.dwarfstd.org">dwarf-discuss-bounces+paul.robinson=sony.com@lists.dwarfstd.org</a>>
<b>On Behalf Of</b> Sergey via Dwarf-discuss<br>
<b>Sent:</b> Wednesday, June 12, 2024 9:57 AM<br>
<b>To:</b> <a href="mailto:dwarf-discuss@lists.dwarfstd.org">dwarf-discuss@lists.dwarfstd.org</a><br>
<b>Subject:</b> [Dwarf-discuss] Request for clarification of handling stack-passed parameters</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"># Request for clarification of handling stack-passed parameters<br>
<br>
## Background<br>
<br>
I came across this while parsing parameters of a variadic function in C. Formal parameters are not sufficient for my case, since all the variadic arguments are described with a single `DW_TAG_unspecified_parameters`, whereas reading `DW_TAG_call_site_parameter`
allows to get their locations and values.<br>
<br>
## Overview<br>
<br>
When generating a DWARF5 of a C function with **more than 6** parameters, the generated `DW_TAG_call_site` contains only **first 6** `DW_TAG_call_site_parameter`s (function's `DW_TAG_formal_parameter`s contain all of them).<br>
<br>
Something I have noticed is that the parameters, which do not get `DW_TAG_call_site_parameter` generated, are all **passed through stack**(whereas first 6 through registers), as evident by function's `DW_TAG_formal_parameter`'s `DW_AT_location` containing `DW_OP_fbreg`.<br>
<br>
## Request for clarification<br>
<br>
It happens both with gcc and clang, however I was unable to find any information in the standard regarding generation of only registed-passed parameters.<br>
<br>
I request clarification on whether it is an issue with implementations, or is there something in the standard which justifies the described behaviour.<o:p></o:p></p>
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