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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Getting back to what the DWARF should look like, I solicited examples on the dwarf-discuss list. gfortran emits sibling DW_TAG_subprogram entries for the SUBROUTINE
and each ENTRY, which seems like a hack. But both IBM XL Fortran and OpenVMS Fortran will emit a DW_TAG_subprogram for the SUBROUTINE, and it will have a child DW_TAG_entry_point for each ENTRY within the SUBROUTINE. Each of these entries will have its own
set of DW_TAG_formal_parameter entries, according to the spec.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">This aligns with my expectation, that the ENTRY is "contained" within a SUBROUTINE, and the natural way for DWARF to represent this is by having entry_point
children of the subprogram DIE.<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""> Roger Ferrer Ibáñez [mailto:rofirrim@gmail.com]
<br>
<b>Sent:</b> Tuesday, October 23, 2018 12:08 PM<br>
<b>To:</b> Robinson, Paul<br>
<b>Cc:</b> jiangmuhui@gmail.com; LLVM-Dev<br>
<b>Subject:</b> Re: [llvm-dev] multi-entry function (debug info)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><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;font-family:"Calibri","sans-serif";color:#1F497D">Regarding multi-entry functions, I'm aware of two cases where this occurs in a source language.
One is when you have optional parameters in C++, which effectively creates one or more overloads for the function; the other is PL/I which allows defining an entry label within the body of the function. For the C++ case, I'd expect the front-end to create
stubs that fill in the defaulted parameters and then tail-call the main function; in this case, each stub would have its own debug-info entry and be treated as its own independent function for debug-info purposes. For PL/I, I would probably do the same, although
I admit it has been a long time since I did any PL/I programming and I never worked on a PL/I compiler.</span><o:p></o:p></p>
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<p class="MsoNormal">Another example of source language with functions that can have more than entry point is Fortran via the ENTRY statement. I think most compilers use an extra integer parameter to discriminate between the different entry points at the call
sites.<o:p></o:p></p>
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