[LLVMdev] [RFC] Less memory and greater maintainability for debug info IR

[Duncan P. N. Exon Smith]

> On Oct 19, 2014, at 7:00 PM, David Blaikie <dblaikie at gmail.com> wrote:
> 
> >> By leveraging the use-list
> >> infrastructure for metadata operands -- i.e., only using value handles
> >> for non-metadata operands -- we'll [...] increase
> >> RAUW speed.
> 
> This is something I know next to nothing about - why is it that use-lists would be applicable to metadata-to-metadata operands, but not for non-metadata operands? 

Metadata isn't allowed to add uses to "regular" IR, since then it would
influence optimizations.  Instead, it's required to refer to them via
value handles.

However, optimizations won't be affected by adding uses to metadata IR.