[LLVMdev] [lld] Relocation reading refactoring

[Shankar Easwaran]

Hi Simon,

The subclasses for ELFFile would use it I thought.

For example if a target wants the basic logic for converting an input 
file to atoms, the target could just override the relocation handler to 
get all the references.

I would use ErrorOr<ReferenceRangeT> to return any errors from 
relocation processing.

Thanks

Shankar Easwaran

On 2/26/2014 3:16 PM, Simon Atanasyan wrote:
> Hi,
>
> Thanks for the explanation. If I understand you properly you suggest
> to move relocation parsing to the class with the following interface.
> Right?
>
> Who will be user of this class? If it is still only ELFFile class,
> what benefits will we get from separation of this logic?
>
> template <class ELFT> class ELFRelocationReader {
> public:
>    ELFRelocationReader(.....);
>
>    // Returns all created references.
>    ReferenceRangeT getAllReferences();
>
>    // Returns references for specified section/symbol.
>    ReferenceRangeT getReferences(StringRef sectionName,
>                                  Elf_Sym *symbol,
>                                  ArrayRef<uint8_t> content);
>
> protected:
>    // Target can override these methods in the inherited class.
>    virtual ELFReference<ELFT> *createReference(Elf_Rela &rel, Elf_Sym *symbol);
>    virtual ELFReference<ELFT> *createReference(Elf_Rel &rel, Elf_Sym *symbol);
> };
>
> On Wed, Feb 26, 2014 at 9:42 PM, Shankar Easwaran
> <shankare at codeaurora.org> wrote:
>> I was thinking of having a separate class that would return a vector of
>> ELFReferences when you the reader looks at a section and symbol.
>>
>> The class would be constructed with
>> _relocationAddendReferences/_relocationReferences.
>>
>> Each subtarget could make use of the functionality and create a different
>> type of ELFReference on a need basis.
> [...]
>
>>> What do you mean by removing relocation reading from the
>>> ELFObjectFile? I considered to customize the relocation reading for
>>> MIPS targets and my first idea was to factor out ELFReference creation
>>> into a couple of virtual functions. The first one is for Elf_Rel, the
>>> second one is for Elf_Rela. Then I planned to override these functions
>>> in the MipsELFFile class. But it looks like you have more profound
>>> idea. Could you share it?


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