[llvm] [RegAlloc] Remove default restriction on non-trivial rematerialization (PR #159211)

[Philip Reames via llvm-commits]

preames wrote:

> Hi @lukel97, is this change expected to affect compilation time a lot? We see quite significant regressions on some protobuf-generated files:
>
...
> 
> I can try preparing a reduced test case, but it's going to take some time.

To quote myself from earlier in the thread: "As the compile time concern reported against https://reviews.llvm.org/D106408 was never identified (i.e. no reproducer shared), we may see a regression on some workloads after this lands. Please do not revert unless a reproducer is available! I have a rough idea of the possible cause, but need a reproducer to confirm a fix."

Once a reproducer is available, we can definitely revert while this is investigated.  A compiler time regression of this magnitude is definitely not acceptable, we just need a reproducer with which to identify it.  


https://github.com/llvm/llvm-project/pull/159211