[clang] [Serialization] Load Specializations Lazily (1/2) (PR #76774)

[Vassil Vassilev via cfe-commits]

vgvassilev wrote:

> > This is a great way to start a new year ;)
> > The phab link is https://reviews.llvm.org/D41416.
> > In general I was wondering could we simplify the implementation by loading the specialization hash table upon module load. That should be relatively cheap as we will read 2 integers per specialization.
> > Perhaps we should put both patches together and that'd allow us to test them if they are on par with https://reviews.llvm.org/D41416 which we use downstream.
> > Thanks for working on this!
> 
> Hi Vassilev, for testing purpose I sent https://github.com/ChuanqiXu9/llvm-project/tree/LoadSpecializationUpdatesLazily. I didn't create stacked review since I feel a standalone branch may be sufficient.
> 

@ChuanqiXu9, I'd prefer to review both patches at the same time. Otherwise we risk of missing some important details.

https://github.com/llvm/llvm-project/pull/76774