[LLVMdev] [proposal] Extensible IR metadata

[Nick Lewycky]

Chris Lattner wrote:
> 
> On Sep 11, 2009, at 7:17 PM, Nick Lewycky wrote:
> 
>> Dan Gohman wrote:
>>> On Sep 11, 2009, at 9:57 AM, Chris Lattner wrote:
>>>> Devang's work on debug info prompted this, thoughts welcome:
>>>> http://nondot.org/sabre/LLVMNotes/ExtensibleMetadata.txt
>>> The document mentions "instructions" a lot. We'll want to be able to
>>> apply metadata to ConstantExprs as well at least, if not also Arguments
>>> (think noalias) and other stuff, so it seems best to just talk about
>>> "values" instead, and DenseMap<Value *, ...> instead of
>>> DenseMap<Instruction *, ...>.
>>
>> I'm wondering that too. Can we replace LLVM function attributes with 
>> metadata? There's been some pushback to adding new function attributes 
>> in the past and it would be nice to be able to prototype new ones 
>> without having to change all of the vm core.
> 
> The pushback has been about adding lots of weird and special purpose 
> extensions, not the encoding.

The bar is higher for getting something into the vm core, as it should 
be. It sounds like we're planning to permit special purpose metadata 
which is why I asked.

If nothing else, it would be more convenient to prototype new extensions 
to find out what they're really worth.

Nick