[PATCH] D36993: [llvm-dwarfdump] Print type names in DW_AT_type DIEs

[David Blaikie via llvm-commits]

On Fri, Sep 1, 2017 at 1:50 PM Adrian Prantl <aprantl at apple.com> wrote:

> On Sep 1, 2017, at 1:46 PM, David Blaikie <dblaikie at gmail.com> wrote:
>
>
>
> On Fri, Sep 1, 2017 at 1:41 PM Adrian Prantl <aprantl at apple.com> wrote:
>
>> On Sep 1, 2017, at 1:36 PM, David Blaikie <dblaikie at gmail.com> wrote:
>>
>> Could we get reasonable test cases for them up-front, to see where things
>> are?
>>
>>
>> You mean for the cases that do work as expected? That seems reasonable.
>>
>
> All the cases, actually - so we can see what they are, whether they need
> improvement, track what those improvements are, etc.
>
>
> That seems excessive to me, since you'd have to create them manually
> (unless yaml-obj makes that trivial?). What about all C(++) types that can
> be produced by clang?
>

Doesn't seem too hideously expensive to produce by hand, are they? maybe
10-15 lines of assembly (even including the abbreviation) per thing? (It
can be really simple DWARF - like a bunch of DW_TAG_variables that have
only a DW_AT_type (no name, no other attributes), etc)


>
> -- adrian
>
>
>
>>
>> -- adrian
>>
>>
>> (I still find it a bit weird to get const/volatile falling out through
>> this process, but yeah, if there's a whole bunch of other cases that fall
>> through this way for now, guess it makes  sense)
>>
>> On Fri, Sep 1, 2017 at 1:24 PM Adrian Prantl via Phabricator <
>> reviews at reviews.llvm.org> wrote:
>>
>>> aprantl added a comment.
>>>
>>> In https://reviews.llvm.org/D36993#859034, @dblaikie wrote:
>>>
>>> > In https://reviews.llvm.org/D36993#858768, @JDevlieghere wrote:
>>> >
>>> > > In https://reviews.llvm.org/D36993#858121, @dblaikie wrote:
>>> > >
>>> > > > In https://reviews.llvm.org/D36993#858093, @JDevlieghere wrote:
>>> > > >
>>> > > > > David, apologies for missing your e-mail. I really hate that it
>>> doesn't automatically show up in Phabricator! 🙁
>>> > > > >
>>> > > > > If the tag doesn't have a name attribute, everything will go
>>> through this function except: `DW_TAG_pointer_type`,
>>> `DW_TAG_ptr_to_member_type`, `DW_TAG_reference_type`,
>>> `DW_TAG_rvalue_reference_type`. The first part explains why `class` and
>>> `struct` don't show up. I prefer this approach because it's guaranteed to
>>> be robust. Every `DW_TAG_*_type` encountered without a name will have
>>> something meaningful printed.
>>> > > > >
>>> > > > > IIRC, the original switch had between 20 and 25 cases.
>>> > > >
>>> > > >
>>> > > > I'm curious what those 20-25 cases were - do you have a
>>> copy/roughly describe their contents? Because while 'const' does print
>>> nicely, (& volatile would be similar) I'm not sure what the other 10 or so
>>> cases might be and whether that's a reasonable way to print them.
>>> > >
>>> > >
>>> > > Here's the list of cases I had originally:
>>> > >
>>> > >   case DW_TAG_array_type:
>>> > >   case DW_TAG_base_type:
>>> > >   case DW_TAG_class_type:
>>> > >   case DW_TAG_const_type:
>>> > >   case DW_TAG_enumeration_type:
>>> > >   case DW_TAG_file_type:
>>> > >   case DW_TAG_interface_type:
>>> > >   case DW_TAG_packed_type:
>>> > >   case DW_TAG_pointer_type:
>>> > >   case DW_TAG_ptr_to_member_type:
>>> > >   case DW_TAG_reference_type:
>>> > >   case DW_TAG_restrict_type:
>>> > >   case DW_TAG_set_type:
>>> > >   case DW_TAG_shared_type:
>>> > >   case DW_TAG_string_type
>>> > >   case DW_TAG_structure_type:
>>> > >   case DW_TAG_subrange_type:
>>> > >   case DW_TAG_subroutine_type:
>>> > >   case DW_TAG_thrown_type:
>>> > >   case DW_TAG_union_type:
>>> > >   case DW_TAG_unspecified_type:
>>> > >   case DW_TAG_volatile_type:
>>> > >
>>> >
>>> >
>>> > Ah, thanks!
>>> >
>>> > I feel like maybe this should be examined more closely (an example of
>>> how each of these would be printed would be ideal, though that might be a
>>> bit much) - for example I don't think it makes sense to print out
>>> subroutine types like "int subroutine" (rather than "int(float, double)",
>>> say) which I /think/ is how they might look based on the current code)
>>>
>>>
>>> Generally agreed, but I think it might make sense to improve this in
>>> separate follow-on patches on a case-by-case basis. Getting the
>>> pretty-printing entirely right would mean that we would have to implement
>>> different pretty-printers for each DW_LANG_foo, since e.g., a C function
>>> type would have to be rendered very differently from the same DWARF
>>> type-representation in an. e.g., Swift or Fortran context. And even if we
>>> choose to always render types as C types it is unclear what to do with
>>> types such as DW_TAG_set_type.
>>>
>>>
>>> Repository:
>>>   rL LLVM
>>>
>>> https://reviews.llvm.org/D36993
>>>
>>>
>>>
>>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20170901/d6a6aeee/attachment.html>