[PATCH] WIP Implement eabi attributes handling in ARMAsmParser

[Logan Chien]

Hi Gabor,

  I found that .eabi_attribute will always overwrite the value defined by
the .fpu directive regardless the order of the directives.  For example,

(1)
.eabi_attribute 12, 3 // Tag_Advanced_SIMD_arch, 3
.fpu neon

(2)
.fpu neon
.eabi_attribute 12, 3 // Tag_Advanced_SIMD_arch, 3

The result binaries of (1) and (2) are identical.  To workaround the first
case, I have to check whether the Tag has been defined or not.  If it is
defined, then we should ignore the value defined by .fpu directive.

>> The GNU assembler does owerwrite it in this case.

  What do you mean by GNU assembler does overwrite this?  May you give an
example?  Thanks.

  Last, but not the least, I am sorry for the duplicated work.  I should
have uploaded my WIP changes to BugZilla earlier.  Thanks for your interest
and efforts to this bug.

Best regards,
Logan


On Tue, Oct 22, 2013 at 1:00 AM, Gabor Ballabas <gaborb at inf.u-szeged.hu>wrote:

> Hi Rafael,
>
> Thanks for the review, but it seems that Logan's solution is more
> advanced than mine
> (and it works as you suggested using the streamer instead of the parser).
> Thanks anyway!
>
> Best regards,
> Gabor Ballabas
>
> On 10/18/13 21:08, Rafael Espíndola wrote:
> > Thank you so much for working on this!
> >
> > Can AttributeEmitter be merged into the target asm streamer? I.E. just
> > add the MaybeSwitchVendor, EmitAttribute, EmitTextAttribute and Finish
> > to the target streamer.
> >
> > +  // Maps for ARM build attributes.
> > +  std::map<unsigned, unsigned> AttributeMap;
> >
> > What is the range of these integers? There is almost certainly a
> > better data structure for doing this. Why is this on the parser? Can't
> > the parser just call EmitAttribute for very .eabi_attribute and let
> > the streamer handle it?
> >
> >
> >
> > On 18 October 2013 09:21, Gabor Ballabas <gaborb at inf.u-szeged.hu> wrote:
> >> This is a work-in-progress patch for this bug:
> >> http://llvm.org/bugs/show_bug.cgi?id=15172
> >> This patch only handles the .eabi_attribute directive but I can make the
> >> .cpu, .fpu and .arch
> >> directives work as well with a similar approach.
> >>
> >> Best regards,
> >> Gabor Ballabas
> >>
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> >>
>
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