[LLVMdev] Metadata

[Chris Lattner]

On Jan 4, 2010, at 3:14 PM, David Greene wrote:
> Is there some documentation about metadata and how to use it  
> somewhere?
> The doxygen-generated stuff obviously doesn't specify things like how
> to create custom metadata kinds and all that jazz.

The metadata design and APIs are still evolving.  I wouldn't recommend  
building anything on it just yet, but I'm hoping it will finalize and  
stabilize this month.  The high-level idea and proposal was here:
http://nondot.org/sabre/LLVMNotes/ExtensibleMetadata.txt

> As a few of us discussed at the latest dev meeting, I'd like to use
> custom metadata to annotate load/store instructions with "nontemporal"
> semantics to allow generation of instructions like MOVNT on x86-based
> targets.  Losing the "nontemporal" annotation won't affect correctness
> so it seems a prime candidate for metadata.
>
> One question: should "nontemporal" be "native" metadata or "external?"

This seems like a very reasonable use of metadata to me!

-Chris