[llvm] r296253 - [DebugInfo] Skip implicit_const attributes when dumping .debug_info. NFC.
Victor Leschuk via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 27 10:39:02 PST 2017
Also readelf does print flag_present in .debug_info, but doesn't print
implicit_const. (Support for DWARFv5 was merged into GNU binutils master
few days ago).
On 02/27/2017 09:29 PM, Victor Leschuk via llvm-commits wrote:
>
> I think flag_present and implicit_const attributes shouldn't be
> treated as similar here: flag_present attributes physically do have a
> record in .debug_info section, while implicit_const attributes are not
> physically mentioned there. Printing implicit_const values when
> dumping .debug_info can be more convenient for reader but it will
> actually violate the definition of dump. When dumping section contents
> we expect to see what is actually there, don't we?
>
>
> On 02/27/2017 09:04 PM, David Blaikie wrote:
>>
>>
>> On Mon, Feb 27, 2017 at 10:00 AM Victor Leschuk
>> <vleschuk at accesssoftek.com <mailto:vleschuk at accesssoftek.com>> wrote:
>>
>>
>>
>> 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.
>>
>>
>> Looks to me like it is:
>>
>> dumping debug info for this code: void f1() { }
>>
>> produces this:
>>
>> .debug_abbrev contents:
>> ...
>> [2] DW_TAG_subprogram DW_CHILDREN_no
>> ...
>> DW_AT_external DW_FORM_flag_present
>>
>> .debug_info contents:
>> ...
>> 0x0000002a: DW_TAG_subprogram [2]
>> ...
>> DW_AT_external [DW_FORM_flag_present] (true)
>>
>> I would expect similar behavior for const_value - that the attribute
>> and its constant value is printed in the debug_info dump.
>>
>>
>>> 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);
>>> }
>>>
>>>
>>> _______________________________________________
>>> llvm-commits mailing list
>>> llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>>
>>
>> --
>> Best Regards,
>> Victor
>>
>
> --
> Best Regards,
> Victor
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
--
Best Regards,
Victor
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20170227/35951555/attachment.html>
More information about the llvm-commits
mailing list