[Bug default/24345] New: Dwz invalidates debug sections generated by --emit-relocs

["vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=24345

            Bug ID: 24345
           Summary: Dwz invalidates debug sections generated by
                    --emit-relocs
           Product: dwz
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: default
          Assignee: nobody at sourceware dot org
          Reporter: vries at gcc dot gnu.org
                CC: dwz at sourceware dot org
  Target Milestone: ---

When compiling hello world, we can keep the relocations in the executable using
linker option --emit-relocs:
...
$ gcc hello.c -g -Wl,--emit-relocs
...

So we have:
...
  [35] .debug_info       PROGBITS         0000000000000000  000011a0
       00000000000005bb  0000000000000000           0     0     1
  [36] .rela.debug_info  RELA             0000000000000000  00003138
       0000000000000c78  0000000000000018   I      44    35     8
...

Using readelf, we find f.i. this string relocation:
...
$ readelf -r -w a.out
Relocation section '.rela.debug_info' at offset 0x3138 contains 133 entries:
  Offset          Info           Type           Sym. Value    Sym. Name +
Addend
000000000024  00200000000a R_X86_64_32       0000000000000000 .debug_str + 1a
...
for this location:
...
    <24>   DW_AT_comp_dir    : (indirect string, offset: 0x1a):
/home/abuild/rpmbuild/BUILD/glibc-2.26/csu
...

However, if we run dwz, then .debug_info is modified: 
...
    <24>   DW_AT_encoding    : 5        (signed)
...
but .rela.debug_info is not.

So, dwz breaks the validity of .rela.debug_info.

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