[PATCH] D71735: [ELF] Don't suggest an alternative spelling for a symbol in a discarded section

[George Rimar via Phabricator via llvm-commits]

grimar added inline comments.


================
Comment at: lld/test/ELF/undef-not-suggest.s:1
+# REQUIRES: riscv
+## Check we don't suggest alternative spelling for relocations to symbols
----------------
MaskRay wrote:
> grimar wrote:
> > MaskRay wrote:
> > > grimar wrote:
> > > > I wonder if we should use yaml2obj (if possible) and make this test be not 'riscv' specific?
> > > A yaml2obj test will degrade test coverage.
> > > 
> > > ```
> > > Symbols:
> > >   - Name:    foo
> > >     Section: .text.foo
> > >   - Name:    for
> > >     Section: .data
> > >   - Name:    .text.foo
> > >     Type:    STT_SECTION
> > >     Section: .text.foo
> > > ### This symbol's name is ".data", instead of "" as produced by an assembler.
> > > ### We need a symbol with empty name for the `.quad .text.foo` test, to test that an empty name will not be suggested.
> > >   - Name:    .data
> > >     Type:    STT_SECTION
> > >     Section: .data
> > > ```
> > I think there is no problem to use an empty name for a symbol.
> > Am I missing something? The following seems just works.
> > 
> > ```
> > --- !ELF
> > FileHeader:
> >   Class:   ELFCLASS64
> >   Data:    ELFDATA2LSB
> >   Type:    ET_DYN
> >   Machine: EM_RISCV
> > Sections:
> >   - Name: .data
> >     Type: SHT_PROGBITS
> > Symbols:
> >   - Name:    ""
> >     Type:    STT_SECTION
> >     Section: .data
> > ```
> If we make the name of the STT_SECTION symbol `.text.foo` empty
> 
> ```
>   - Name:    ""
>     Type:    STT_SECTION
>     Section: .text.foo
>   - Name:    ""
>     Type:    STT_SECTION
>     Section: .data
> ```
> 
> Then we can't reference it in a relocation:
> ```
>   - Name: .rela.rodata               
>     Type: SHT_RELA                   
>     Link: .symtab                    
>     Info: .rodata                    
>     Relocations:                     
>       - Offset: 0x0                  
>         Symbol: .text.foo            
>         Type:   R_X86_64_64          
>       - Offset: 0x8                  
>         Symbol: foo                  
>         Type:   R_X86_64_64
> ```
> 
> ```
> yaml2obj: error: unknown symbol referenced: '.text.foo' by YAML section '.rela.rodata'
> ```
But can't you reference it by index?

```
--- !ELF
FileHeader:
  Class:   ELFCLASS64
  Data:    ELFDATA2LSB
  Type:    ET_DYN
  Machine: EM_X86_64
Sections:
- Name: .rodata             
  Type: SHT_PROGBITS
- Name: .text.foo               
  Type: SHT_PROGBITS
- Name: .rela.rodata               
  Type: SHT_RELA                   
  Link: .symtab                    
  Info: .rodata                  
  Relocations:                     
    - Offset: 0x0                  
      Symbol: 1            
      Type:   R_X86_64_64
Symbols:
- Name:    ""
  Type:    STT_SECTION
  Section: .text.foo
```


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71735/new/

https://reviews.llvm.org/D71735