`ld.lld` does not rename relocation sections with related output section name

[thelastlin]

Sometimes we might want to rename sections in relocatable object files with a linker script.

By convention, a name of relocation section is based on the section which the relocations apply, for example, the relocation section for ".foo" would have the name ".rel[a].foo".

---

Linker Script:

SECTIONS {
  .foo : {
    *(.bar)
  }
}

Input relocatable object file's section headers:

  [Nr] Name              Type            Flg Lk Inf Al
  [ 0]                   NULL                 0   0  0
  [ 1] .foo              PROGBITS         AX  0   0  4
  [ 2] .rela.foo         RELA             I   8   1  8
...

Output relocatable object file's section headers:
ld.bfd / ld.gold:

  [Nr] Name              Type            Flg Lk Inf Al
  [ 0]                   NULL                 0   0  0
  [ 1] .bar              PROGBITS         AX  0   0  4
  [ 2] .rela.bar         RELA             I   8   1  8
...

ld.lld:

  [Nr] Name              Type            Flg Lk Inf Al
  [ 0]                   NULL                 0   0  0
  [ 1] .bar              PROGBITS         AX  0   0  4
  [ 2] .rela.foo         RELA             I   8   1  8
...

[MaskRay]

Thanks. #67910 should work but we need some tests. I'll add some to linkerscript/

[llvmbot]

@llvm/issue-subscribers-lld-elf

Author: Xavier Hsinyuan (thelastlin)

Sometimes we might want to rename sections in relocatable object files with a linker script.

By convention, a name of relocation section is based on the section which the relocations apply, for example, the relocation section for ".foo" would have the name ".rel[a].foo".

---

Linker Script:

SECTIONS {
  .foo : {
    *(.bar)
  }
}

Input relocatable object file's section headers:

  [Nr] Name              Type            Flg Lk Inf Al
  [ 0]                   NULL                 0   0  0
  [ 1] .foo              PROGBITS         AX  0   0  4
  [ 2] .rela.foo         RELA             I   8   1  8
...

Output relocatable object file's section headers:
ld.bfd / ld.gold:

  [Nr] Name              Type            Flg Lk Inf Al
  [ 0]                   NULL                 0   0  0
  [ 1] .bar              PROGBITS         AX  0   0  4
  [ 2] .rela.bar         RELA             I   8   1  8
...

ld.lld:

  [Nr] Name              Type            Flg Lk Inf Al
  [ 0]                   NULL                 0   0  0
  [ 1] .bar              PROGBITS         AX  0   0  4
  [ 2] .rela.foo         RELA             I   8   1  8
...