[PATCH] D58615: [llvm-objdump] Add `Version Definitions` dumper

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Higuoxing added a comment.

In D58615#1409090 <https://reviews.llvm.org/D58615#1409090>, @jhenderson wrote:

> How many verdefs do you get in a typical file? I'm looking at the hard-coded indentation amount of Verdaux entries after the first, and thinking that that indentation doesn't look quite right, and would look worse the higher the index, due to the first column changing in width. I think it should line up with the previous name, but I don't think it currently does. Additionally, if I'm not mistaken the formatting will look something like:
>
>   1 0x01 0x075bcd15 foo
>   2 0x02 0x3ade68b1 VERSION_1
>   ...
>   9 0xab 0x12345678 something
>   10 0xdc 0xabcdef90 something_else
>
>
> which doesn't look great. Assuming it's not unusual to have 10+ entries, could you do something that ensures the column width is consistent?


I think there could be an object file that has over 10 entries in its `verdef` section.
However, `gnu-objdump` has the same problem. I currently have no idea how to make it compatible with `gnu-objdump` and ensure the column width is consistent.

  --- !ELF
  FileHeader:
    Class:           ELFCLASS64
    Data:            ELFDATA2LSB
    Type:            ET_DYN
    Machine:         EM_X86_64
    Entry:           0x0000000000001000
  Sections:
    - Name:            .gnu.version_d
      Type:            SHT_GNU_verdef
      Flags:           [ SHF_ALLOC ]
      Address:         0x0000000000000230
      Link:            .dynstr
      AddressAlign:    0x0000000000000004
      Info:            0x0000000000000010
      Entries:
        - Version:         1
          Flags:           1
          VersionNdx:      1
          Hash:            123456789
          Names:
            - VERSION_1
        - Version:         1
          Flags:           2
          VersionNdx:      2
          Hash:            987654321
          Names:
            - VERSION_2
        - Version:         1
          Flags:           2
          VersionNdx:      3
          Hash:            98765321
          Names:
            - VERSION_3
        - Version:         1
          Flags:           2
          VersionNdx:      4
          Hash:            98654321
          Names:
            - VERSION_4
        - Version:         1
          Flags:           2
          VersionNdx:      5
          Hash:            98765421
          Names:
            - VERSION_5
        - Version:         1
          Flags:           2
          VersionNdx:      6
          Hash:            989654321
          Names:
            - VERSION_6
        - Version:         1
          Flags:           2
          VersionNdx:      7
          Hash:            997654321
          Names:
            - VERSION_7
        - Version:         1
          Flags:           2
          VersionNdx:      8
          Hash:            997654321
          Names:
            - VERSION_8
        - Version:         1
          Flags:           2
          VersionNdx:      9
          Hash:            997654321
          Names:
            - VERSION_9
        - Version:         1
          Flags:           2
          VersionNdx:      10
          Hash:            997654321
          Names:
            - VERSION_10
        - Version:         1
          Flags:           2
          VersionNdx:      11
          Hash:            997654321
          Names:
            - VERSION_11
        - Version:         1
          Flags:           2
          VersionNdx:      12
          Hash:            997654321
          Names:
            - VERSION_12
        - Version:         1
          Flags:           2
          VersionNdx:      13
          Hash:            997654321
          Names:
            - VERSION_13
  DynamicSymbols:
    Global:
      - Name:            bar
  ...



================
Comment at: tools/llvm-objdump/ELFDump.cpp:314
+    outs() << VerdefIndex ++ << " "
+           << format("0x%02" PRIx16 " ", (uint16_t)Verdef->vd_flags)
+           << format("0x%08" PRIx32 " ", (uint32_t)Verdef->vd_hash);
----------------
jhenderson wrote:
> This only prints a width of 2, but the flags could require four digits. Are there never any flags beyond 0xff?
As for `vd_flags` field, its value can be 0x01(VER_FLG_BASE) or 0x02(VER_FLG_WEAK).
See, https://docs.oracle.com/cd/E19957-01/806-0641/chapter6-80869/index.html


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