[llvm-dev] [lld] Hiding original type of GOT related relocations

[Rui Ueyama via llvm-dev]

On Fri, Nov 20, 2015 at 10:13 PM, Simon Atanasyan <simon at atanasyan.com>
wrote:

> Hi,
>
> There are more than one MIPS relocations which need GOT entry
> creation. Let's consider two of them R_MIPS_GOT16 and R_MIPS_CALL16
> [1]. R_MIPS_GOT16 is applicable to local and external symbols and
> performs a different calculation in each cases [2]. R_MIPS_CALL16 is
> applicable to external symbols only and a linker should show an error
> if it finds R_MIPS_CALL16 with a local target. Now LLD in the
> `InputSectionBase<ELFT>::relocate` methods hides original type of GOT
> relocations and always use the result of `Target->getGotRefReloc()`
> call. In case of MIPS it is R_MIPS_GOT16. It makes impossible to
> perform target symbol type checking and the error generation in the
> `MipsTargetInfo<ELFT>::relocateOne` method.
>

I guess there's no need to hide the type. It's just that because it works
for x86, x86-64 or aarch64. If mips requires more info, it should be ok to
change that.


> Is it really necessary to hide original relocation type? If a target
> has multiple GOT related relocations it might just add more `cases` to
> its `relocateOne` method.
>
> [1] ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf page 4-19
> [2] ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf page 4-20
>
> --
> Simon Atanasyan
>
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