[PATCH] IR: Add specialized debug info metadata nodes

[Duncan P. N. Exon Smith]

> On 2015-Feb-04, at 15:37, Frédéric Riss <friss at apple.com> wrote:
> 
>>> 
>>> - The word 'context' is overloaded: `MDNode::getContext()` already
>>>   exists, and returns an `LLVMContext&`; `DIDescriptor` uses 'context'
>>>   to mean "the node that this one is defined inside".  I chose the
>>>   word 'parent' instead of 'context' here.  Is this word okay?  If
>>>   not, what about 'scope'?  This will be reflected in the assembly
>>>   changes to come (I'd like the C++ names to match the assembly names,
>>>   although technically it's not necessary).
>>> 
>>> I'd /probably/ go with scope (we already have scope in the MDLocations, so that seems consistent), but fairly on-the-fence.
>>> 
>> 
>> Weirdly, I didn't even notice that :).  In that case I like 'scope'
>> better too.  I'll update to that before commit.
> 
> Seems most natural. Can the futur getScope() return something that doesn’t derive from MDScope?

I don't think so.