[PATCH] D62516: [llvm-readobj/llvm-readelf] - Implement GNU style dumper of the SHT_GNU_verneed section.

[Fangrui Song via Phabricator via llvm-commits]

MaskRay accepted this revision.
MaskRay added inline comments.
This revision is now accepted and ready to land.


================
Comment at: tools/llvm-readobj/ELFDumper.cpp:3436
   StringRef SymTabName = unwrapOrError(Obj->getSectionName(SymTab));
   OS << " Addr: " << format_hex_no_prefix(Sec->sh_addr, 16)
      << "  Offset: " << format_hex(Sec->sh_offset, 8)
----------------
grimar wrote:
> MaskRay wrote:
> > Nit: `"  Addr: "` (two spaces before `"Addr:"`)
> > 
> > GNU readelf prints `0x` prefix for `.gnu.version_d` and `.gnu.version_r` but omits the prefix for `.gnu.version`... I think the inconsistency may be due to a bug. We may stick with one style :)
> GNU output is:
> 
> ```
> Version symbols section '.gnu.version' contains 6 entries:
>  Addr: 0000000000000000  Offset: 0x000280  Link: 7 (.dynsym)
> readelf: Warning: Cannot interpret virtual addresses without program headers.
>   000:457f              464c               102               901              
>   004:   0 (*local*)       0 (*local*)    
> 
> Version definition section '.gnu.version_d' contains 3 entries:
>   Addr: 0x0000000000000000  Offset: 0x00028c  Link: 8 (.dynstr)
>   000000: Rev: 1  Flags: none  Index: 2  Cnt: 1  Name: VERSION1
>   0x001c: Rev: 1  Flags: none  Index: 3  Cnt: 2  Name: VERSION2
>   0x0038: Parent 1: VERSION1
> readelf: Warning: Invalid vd_next field of 0
> 
> Version needs section '.gnu.version_r' contains 2 entries:
>  Addr: 0x0000000000000000  Offset: 0x0002cc  Link: 8 (.dynstr)
>   000000: Version: 1  File: verneed1.so.0  Cnt: 2
>   0x0010:   Name: v1  Flags: none  Version: 4
>   0x0020:   Name: v2  Flags: none  Version: 5
>   0x0030: Version: 1  File: verneed2.so.0  Cnt: 1
>   0x0040:   Name: v3  Flags: none  Version: 6
> 
> ```
> 
> There are following inconsistencies can be observed:
> 1) Number of spaces before `Addr`. For `.gnu.version_d` there are 2, for other sections - 1.
> So having a single space is a bit more consistent with GNU (2:1) :)
> 
> I would probably leave a single space, because this line is kind of prolog(header),
> it is different from following entries (and hence can be separated).
> 
> 2) `0x` prefix, yes. As you mentioned, GNU omits it for `.gnu.version`, but not only that. It also does
> it for the first entries. IMO looks ugly and crazy inconsistent. So I am always printing it.
1 space looks good to me.

I didn't know the GNU output is so bad until you printed it out.. Pick the style that is aesthetically appealing then :)

`000000` -> `0x0000` I believe this is also a GNU readelf bug.


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  https://reviews.llvm.org/D62516/new/

https://reviews.llvm.org/D62516