[PATCH] Support native mach-o names in MachOFormat.h

[Charles Davis]

On Aug 19, 2013, at 4:22 PM, Nick Kledzik wrote:

> Wow, that was fast Charles!
Yeah, I've been sitting on those patches for a while.
> 
> I did not know that Support/MachO.h even existed!
Outside of LLDB, hardly anyone does. They added it, and AFAIK they're the only ones that use it right now. (These patches will obviously change that.)
>   Why does Object/MachOFormat.h and it both define the same things differently?
I don't know, and that's why I wanted to get rid of one. I suspect that whoever added Object/MachOFormat.h probably didn't know about Support/MachO.h either.
>    There was some recent changes to ELF headers to layer them.  Is there something analogous we need to do for mach-o?
We used to do something similar--we had the MachOObject class that does about the same thing as the ELFFile class (i.e. it was a low-level interface to a Mach Object), except without the heavy template meta-programming. MachOObjectFile was then just a thin wrapper around it, just as ELFObjectFile is now just a wrapper around ELFFile. But Rafael Espíndola got rid of that a while back, saying something about the InMemoryStruct template not working right. (He also wanted to add the kind of template meta-programming to Mach-O that ELF was using for its structs, but that got shot down.)

Chip

> 
> -Nick
> 
> On Aug 19, 2013, at 3:14 PM, Charles Davis <cdavis5x at gmail.com> wrote:
>> On Aug 19, 2013, at 4:02 PM, Eric Christopher wrote:
>> 
>>> Probably wouldn't take much to fix up all the name uses and leave out
>>> the conditional?
>> I have two patches; one does what Nick's patch does, but to <llvm/Support/MachO.h>, and also updates everything using it in LLVM to use the new names, and one that strips out the now-redundant <llvm/Object/MachOFormat.h> header and changes everything using *that* to use the new names.
>> 
>> Chip
>> <0001-Support-MachO-Add-a-bunch-of-defines.patch><0002-Move-everything-depending-on-Object-MachOFormat.h-ov.patch>
>> 
>>> 
>>> -eric
>>> 
>>> On Mon, Aug 19, 2013 at 2:57 PM, Nick Kledzik <kledzik at apple.com> wrote:
>>>> [+patch]
>>>> 
>>>> include/llvm/Object/MachOFormat.h is odd in that it makes up new names for the public mach-o format structs and constants (e.g. it defines LCT_Segment instead of LC_SEGMENT). LLVM does not handle ELF this way.  LLVM defines SHT_PROGBITS just like the standard ELF header (although llvm puts them into a namespace).  This current set up makes it hard to reconcile the public mach-o documentation with llvm source code.
>>>> 
>>>> This patch adds all the standard mach-o names for structs and constants in the llvm::object::mach_o namespace.  All the existing names remain, but I put them inside #ifndef LLVM_NO_OLD_MACH_O_NAMES, so that if someone wanted to switch to the standard names they could define LLVM_NO_OLD_MACH_O_NAMES, do a full build, and update whatever failures are seen.
>>>> 
>>>> This issue came up during a code review of lld, as to why lld was defining it own mach-o constants instead of using the ones in llvm.
>>>> 
>>>> -Nick
>>>> 
>>>> 
>>>> 
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