[llvm] r296253 - [DebugInfo] Skip implicit_const attributes when dumping .debug_info. NFC.

[Victor Leschuk via llvm-commits]

On 02/27/2017 08:04 PM, David Blaikie wrote:
> Skipping these values doesn't seem to be correct - in the case of 
> flag_present, I think the value is still rendered in the dump, is it not?
Do you mean that the value is somehow mentioned in .debug_info section? 
It is not.
> I would expect the same for implicit_const values. (also, this needs 
> test coverage either way)
Yes, you are correct. I will create tests when we decide what's right 
behavior here.

I think skipping is correct here: we are dumping .debug_info data based 
on attributes stored in AbbrevDecl, this code was based on assumption 
that every attribute has representation in .debug_info section, that was 
before implicit_const form was introduced.
>
> On Sat, Feb 25, 2017 at 5:27 AM Victor Leschuk via llvm-commits 
> <llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>> wrote:
>
>     Author: vleschuk
>     Date: Sat Feb 25 07:15:57 2017
>     New Revision: 296253
>
>     URL: http://llvm.org/viewvc/llvm-project?rev=296253&view=rev
>     Log:
>     [DebugInfo] Skip implicit_const attributes when dumping
>     .debug_info. NFC.
>
>     When dumping .debug_info section we loop through all attributes
>     mentioned in
>     .debug_abbrev section and dump values using
>     DWARFFormValue::extractValue().
>     We need to skip implicit_const attributes here as their values are not
>     really located in .debug_info but directly in .debug_abbrev. This
>     patch fixes
>     triggered assert() in DWARFFormValue::extractValue() caused by
>     trying to
>     access implicit_const values from .debug_info.
>
>     Modified:
>         llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp
>
>     Modified: llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp
>     URL:
>     http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp?rev=296253&r1=296252&r2=296253&view=diff
>     ==============================================================================
>     --- llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp (original)
>     +++ llvm/trunk/lib/DebugInfo/DWARF/DWARFDie.cpp Sat Feb 25
>     07:15:57 2017
>     @@ -329,6 +329,12 @@ void DWARFDie::dump(raw_ostream &OS, uns
>
>              // Dump all data in the DIE for the attributes.
>              for (const auto &AttrSpec : AbbrevDecl->attributes()) {
>     +          if (AttrSpec.Form == DW_FORM_implicit_const) {
>     +            // We are dumping .debug_info section ,
>     +            // implicit_const attribute values are not really
>     stored here,
>     +            // but in .debug_abbrev section. So we just skip such
>     attrs.
>     +            continue;
>     +          }
>                dumpAttribute(OS, *this, &offset, AttrSpec.Attr,
>     AttrSpec.Form,
>                              Indent);
>              }
>
>
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-- 
Best Regards,
Victor

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