llvm dev - Jul 2014 - [LLVMdev] [PATCH] Symbol offsets

Rafael Espíndola <rafael.espindola at gmail.com> writes:
> On 20 July 2014 18:18, Ben Gamari <bgamari.foss at gmail.com> wrote:
>> Rafael Espíndola <rafael.espindola at gmail.com> writes:
>>
>>> Now that aliases can have any expressions, can't you use
something like
>>>
>>> @data = private global [2 x i32] [i32 42, i32 43]
>>> @symbol = alias getelementptr ([2 x i32]* @data, i32 0, i32 1)
>>>
>>> This produces
>>>
>>> .Ldata:
>>>         .long   42                      # 0x2a
>>>         .long   43                      # 0x2b
>>> ...
>>>         .globl  symbol
>>> symbol = .Ldata+4
>>>
>>> That is, in the object file there is only one symbol (named symbol)
>>> and it is at offset 4.
>>>
>> How would one define the body of the function `symbol` in this case?
>
> I don't think it would work. For LLVM generated "data" (like
function
> bodies) it seems something like the prefix feature is what is needed.
>
I suspected this was the case. Is a rework of prefix support likely to
make it in for 3.5?

Cheers,

- Ben

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> I suspected this was the case. Is a rework of prefix support likely to
> make it in for 3.5?
>
Unlikely. It has branched already and I don't know of anyone working on it.

Cheers,
Rafael

Rafael Espíndola <rafael.espindola at gmail.com> writes:
>> I suspected this was the case. Is a rework of prefix support likely to
>> make it in for 3.5?
>>
>
> Unlikely. It has branched already and I don't know of anyone working on
it.
>
Fair enough. If there is consensus around a reasonably concrete proposal
I would be happy to put together a patch (acknowledging that it probably
won't make it in for 3.5). Does Reid's proposal seem reasonable?

Cheers,

- Ben

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