[LLVMdev] How to reduce the footprint of MDNodes? (About the comment you made at BOF LTO)

[Chandler Carruth]

On Tue, Nov 12, 2013 at 4:31 PM, David Blaikie <dblaikie at gmail.com> wrote:

> Where would the encoding schema be specified?
>>>
>>
>> Same question applies to a string encoding. We have to define the schema
>> somewhere clearly. I'm just lobbying for the textual IR and the APIs to
>> both operate directly on N fields, and just make the memory representation
>> dense.
>>
>
> The difference here is that debug info parsing code would know the schema
> externally - so the metadata itself wouldn't have to be self-describing or
> typed in any way. Just a flat series of bytes of a fixed size would be
> sufficient. (then leaving out the fields that refer to other IR constructs
> such as functions, variables, etc)
>
> But if we could make general metadata generally more compact that'd be
> nice too and maybe sufficient/instead/not worth the added complexity in
> debug info code of pulling out fields in the debug info handling code.
>

If it makes it possible for humans to read, author, and adjust debug info
test cases, that would also be worth it IMO. I'm really unsatisfied by the
reliance on C-code-in-comments to figure out what on earth the debug info
came from.
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