[LLVMdev] [proposal] Extensible IR metadata

[Chris Lattner]

On Sep 11, 2009, at 9:00 PM, Nick Lewycky wrote:

> 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.

Yep, I completely agree!

-Chris