[Dwarf-Discuss] debug_names - what should go in ?

[Jim Ingham]

This is certainly how lldb treats the Apple names and types indexes.  If present, we don't do any indexing of DWARF, we just use the indexes, and of course any local context.

Enums have been a long-standing problem with this approach, the Apple indices only mention the enum type, so you can't use them in expressions in they way you would type them in code.  It would be nice to fix that.

Jim


> On Apr 10, 2018, at 10:37 AM, Eric Christopher via Dwarf-Discuss <dwarf-discuss at lists.dwarfstd.org> wrote:
> 
> I have nothing to add to what Paul just said :)
> 
> This is definitely the intent and what we should do.
> 
> -eric
> 
> On Tue, Apr 10, 2018 at 10:26 AM Paul Robinson via Dwarf-Discuss <dwarf-discuss at lists.dwarfstd.org> wrote:
> The intent of the index is given pretty plainly in the non-normative text at the bottom of p.137; you should be able to look up any unqualified name in the index.  If the normative text doesn't accomplish that, we have an opportunity to improve the spec. J
> 
>  
> 
> FWIW here's my take:
> 
>  
> 
> Enumerations are a bit unusual in that the enumerators are children of the enumeration type, but the enumerator names are not qualified by the type name (usually?a C++ enum-class should not put enumerators into the index, I think).  But you need some rule that excludes enumerations that are not otherwise "global" (e.g., they are contained in a class or local to a function).
> 
>  
> 
> For imported entities, I'd say if the imported entity would have satisfied the criteria for inclusion in the index if it had been "inlined" at the point where it was imported, then it ought to be in the index.
> 
> --paulr
> 
>  
> 
>  
> 
> From: Dwarf-Discuss [mailto:dwarf-discuss-bounces at lists.dwarfstd.org] On Behalf Of David Blaikie via Dwarf-Discuss
> Sent: Tuesday, April 10, 2018 12:30 PM
> To: Pavel Labath
> Cc: dwarf-discuss at lists.dwarfstd.org
> Subject: Re: [Dwarf-Discuss] debug_names - what should go in ?
> 
>  
> 
> Yep - sounds like it to me.
> 
> I suppose, arguably, one could say that successful name lookups of things in the index can be fast, while lookups that fail, or find names not in the index may be slow - but that seems unacceptable to me (in many cases "slow" would be "prohibitively slow" especially the first time - since it'd amount to the non-index case: the consumer having to build its own index from scratch)
> 
> Maybe Adrian or Eric can talk to how the Apple indexes worked in these cases.
> 
>  
> 
> On Tue, Apr 10, 2018 at 9:24 AM Pavel Labath <labath at google.com> wrote:
> 
> On Tue, 10 Apr 2018 at 16:44, David Blaikie <dblaikie at gmail.com> wrote:
> 
> I'd say any case where a consumer couldn't actually rely on the table to do name resolution would be a bug - or at least something that needs to be seriously considered/discussed/figured out how the name table can be used in those situations.
> 
>  
> 
> Agreed.
> 
>  
> 
> This question can be demonstrated on a simple c++ program
> 
> ============
> 
> namespace namesp1 { int var; }
> 
> namespace namesp2 = namesp1; // DW_TAG_imported_declaration
> 
>  
> 
> enum enum_type { enumerator }; // DW_TAG_enumeration_type, DW_TAG_enumerator
> 
>  
> 
> int main() {
> 
>   return namesp2::var + enumerator;
> 
> }
> 
> ============
> 
>  
> 
> Debugging with gdb (without any indexes), the following 4 expressions succeed
> 
> 1) namesp1::var
> 
> 2) namesp2::var
> 
> 3) (enum_type)0
> 
> 4) enumerator
> 
>  
> 
> The question is how should an index-aware debugger find the entities referenced by expressions 2 and 4 if they are not present in the index?
> 
>  
> 
> They way I see it -- it can't. Which would be a bug in the spec by your definition.
> 
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