[PATCH] Implement ARM EHABI

[Ilyong Cho]

Thank you for response.

Does llvm-mc deal with unwind directive? That's awsome!

I've posted a snippet here( https://gist.github.com/ILyoan/5392936). I've
only posted stack related parts with comments but it contains all
information to exception table. So I believe you can test with it.

Regards
Ilyong Cho
 Hi,

  Sorry for the late reply.  I have read your patch.  It seems that there
are several differences.  Maybe we can cooperate to merge them in to one
patch (if you don't mind.)

*1. Add new .movsp directive.*

This part LGTM.

*2. Much more delicate algorithm for $SP offset. *

I have to admit that the algorithm in my patch is likely to be different
from the one in gas.  Due to the lack of documentation, I have to guess the
algorithm by disassembling the object files generated by gas.  Since I have
only tested them with the assembly files generated by clang, it might be
incompatible with gas when they are used as an assembler.  Especially, when
there are multiple .setfp directives in a function.

May you attach the assembly file that you are trying to assemble?  I can
try to deal with llvm-mc these days.

Sincerely,
Logan



On Mon, Apr 15, 2013 at 5:30 PM, Ilyong Cho <ilyoan at gmail.com> wrote:

> Or we can just ignore such cases.
> Becasue it's very very weird and at least there is a another option to
> conpile it :)
>
> Regards
> Ilyong Cho
> 2013. 4. 15. 오후 6:26에 "Ilyong Cho" <ilyoan at gmail.com>님이 작성:
>
> Ooops I've accidently pushed send button :)
>>
>> Anyway, IMO, There is no problem the patch from Logan regarding to the
>> issue I mentioned, because there is no way to produce the case right now.
>> But after llvm-mc understand unwind directive, it can be the case.
>>
>> Regards,
>> Ilyong Cho
>> 2013. 4. 15. 오후 6:12에 "Ilyong Cho" <ilyoan at gmail.com>님이 작성:
>>
>>> Hi Anton
>>>
>>> Actually I'm not sure if it is possible to make such test cases using
>>> higher language. And llvm-mc looks like does not understand unwind
>>> directives(am I right?) so it is impossible to make test case using llvm-mc.
>>>
>>> The counter example is a wired situation that pushes the same register
>>> into stack twice from function prologue(I just analyzed reviewing source
>>> code, so I can be wrong). There are some such handmade assemblies In my
>>> personal project for some reasons(ex. stack manipulation)
>>> And I'm pretty sure that higher language compilers never generate such
>>> assembly.
>>>  2013. 4. 15. 오후 5:28에 "Anton Korobeynikov" <anton at korobeynikov.info>님이
>>> 작성:
>>>
>>>> Hello,
>>>>
>>>> > I've juat looked the patch and I think it looks good but I found the
>>>> > implementation of that patch is different from gas's. I have a weird
>>>> use
>>>> > case (hand made ARM assembly with a complex function prologue) that
>>>> the
>>>> > patch on D414 couldn't cover but gas implementation(and mine) could
>>>> cover.
>>>> Will it be possible for you to provide a testcase then? Knowing that
>>>> the code is broken is not a good thing for committing it :)
>>>>
>>>> --
>>>> With best regards, Anton Korobeynikov
>>>> Faculty of Mathematics and Mechanics, Saint Petersburg State University
>>>>
>>>
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