[llvm-dev] Should we split llvm Support and ADT?

[Chris Lattner via llvm-dev]

> On May 26, 2017, at 5:47 PM, Zachary Turner via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> Changing a header file somewhere and having to spend 10 minutes waiting for a build leads to a lot of wasted developer time.
> 
> The real culprit here is tablegen.  Can we split support and ADT into two - the parts that tablegen depends on and the parts that it doesn’t?

In all the comments downthread, I think there is one thing that hasn't been mentioned: doing a split like this makes tblgen evolution more difficult.  If libsupport was split into “used by tblgen” and “not used by tblgen” sections, and then a new tblgen feature needs to use other parts of libsupport, they’d have to be moved into the “used by tblgen” directory.  

Splitting libsupport as a whole out into its own llvm subproject has come up many times though, and does make a lot of sense.

-Chris