llvm dev - Jul 2013 - [LLVMdev] Hi, people, I propose to move Debug and Object File related headers out of Support

On Jul 4, 2013, at 10:22 PM, 罗勇刚(Yonggang Luo) wrote:
> 
> 在 2013-7-4 下午8:53，"Charles Davis" <cdavis5x at
gmail.com>写道：
> >
> >
> > On Jul 4, 2013, at 1:43 AM, 罗勇刚(Yonggang Luo) wrote:
> >
> > > LLVM is a modularized software system, so I hope it's was
modularized,
> > > And ELF.h is definitely belongs to Object by classification,
> > > The things that confused me is the ELF.h was placed under Support
and
> > > don't know why.
> > Because it's also used by the MC layer's direct object
emission support.
> thanks for your response, did MC layer's direct object emission depends
on Object library?
> 
Nope. The Object library only reads object files. MC, on the other hand, only
writes object files.

Chip

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On Thu, Jul 4, 2013 at 10:21 PM, Charles Davis <cdavis5x at gmail.com>
wrote:
>
> On Jul 4, 2013, at 10:22 PM, 罗勇刚(Yonggang Luo) wrote:
>
>
> 在 2013-7-4 下午8:53，"Charles Davis" <cdavis5x at
gmail.com>写道：
> >
> >
> > On Jul 4, 2013, at 1:43 AM, 罗勇刚(Yonggang Luo) wrote:
> >
> > > LLVM is a modularized software system, so I hope it's was
modularized,
> > > And ELF.h is definitely belongs to Object by classification,
> > > The things that confused me is the ELF.h was placed under Support
and
> > > don't know why.
> > Because it's also used by the MC layer's direct object
emission support.
> thanks for your response, did MC layer's direct object emission depends
on
> Object library?
>
> Nope. The Object library only reads object files. MC, on the other hand,
> only writes object files.
>
That’s true for object emission, but MC already depends on libObject, and
at least some of the more experimental parts of MC actually use it to read
files.

However, - I believe nobody mentioned this - I think the point of having
ELF.h and friends in Support is that they’re intended to (more or less
exactly) match the headers provided by the system. Most of what’s there is
duplicated in a friendlier form (for ObjectFile-related stuff), or just to
match the LLVM style (notably Object/MachOFormat.h) in Object.

-- Ahmed Bougacha

> Chip
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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On Jul 5, 2013, at 10:17 AM, Ahmed Bougacha wrote:
> On Thu, Jul 4, 2013 at 10:21 PM, Charles Davis <cdavis5x at
gmail.com> wrote:
> 
> On Jul 4, 2013, at 10:22 PM, 罗勇刚(Yonggang Luo) wrote:
> 
>> 
>> 在 2013-7-4 下午8:53，"Charles Davis" <cdavis5x at
gmail.com>写道：
>> >
>> >
>> > On Jul 4, 2013, at 1:43 AM, 罗勇刚(Yonggang Luo) wrote:
>> >
>> > > LLVM is a modularized software system, so I hope it's was
modularized,
>> > > And ELF.h is definitely belongs to Object by classification,
>> > > The things that confused me is the ELF.h was placed under
Support and
>> > > don't know why.
>> > Because it's also used by the MC layer's direct object
emission support.
>> thanks for your response, did MC layer's direct object emission
depends on Object library?
>> 
> Nope. The Object library only reads object files. MC, on the other hand,
only writes object files.
> 
> That’s true for object emission, but MC already depends on libObject,
Huh. You're right, looking at MC's LLVMBuild.txt
file.
> and at least some of the more experimental parts of MC actually use it to
read files.
That's right, the new object disassembler stuff (that you are working on, if
I'm not mistaken!) that was just added needs libObject.

But as for debug info, it is true that DebugInfo only knows how to read it, and
CodeGen knows how to write it (but not read it). So for now, the DWARF stuff at
least definitely needs to stay in Support.
> 
> However, - I believe nobody mentioned this - I think the point of having
ELF.h and friends in Support is that they’re intended to (more or less exactly)
match the headers provided by the system.
Agreed, though I'm not sure if that justifies them being in Support instead
of Object.
> Most of what’s there is duplicated in a friendlier form (for
ObjectFile-related stuff), or just to match the LLVM style (notably
Object/MachOFormat.h) in Object.
I have to say, I believe that this duplication is an (admittedly minor) problem,
because now at least <llvm/Support/MachO.h> and
<llvm/Object/MachOFormat.h> are out of sync. I think we should get rid of
one in favor of the other. Personally, I want to keep the former and dump the
latter, but LLVM uses mostly the latter when it needs to work with Mach-O files,
so I'm not sure how the rest of the community feels--which header stays and
which one goes, where the header should go, or if this is even a bike shed
they'd want to repaint.

Chip
> 
> -- Ahmed Bougacha
>  
> Chip
> 
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
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> 
> 
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