[llvm-dev] alloca and frame pointer changes (regression?)

[Bagel via llvm-dev]

In the process of moving my backend from release/9.x to release/12.x (not an 
easy task), I noticed some changes in generated code.

Consider a nested (i.e. not at the out level of a function) alloca of an object 
(larger than register size).  In release/9.x, this did not call for a frame 
pointer.  In release/12.x it does -- but really doesn't need it.  This change 
happens for other architectures as well.

When did this change happen and why?

Thanks,
Brian