[llvm-commits] two-byte return optimization for AMD

[Chris Lattner]

On Dec 7, 2008, at 11:04 PM, Evan Cheng wrote:

> I am not crazy about adding a subtarget feature for a micro-
> optimization. If you want to enable a family of optimizations for AMD
> chips, please just add something like a FeatureAMD feature.

Why not?  What if some AMD chips have this "feature/problem" and  
others don't?

> Also, it seems awfully expensive to perform a full machine function
> pass. This seems like something that can be done at instruction
> selection time?

It needs to happen after prolog epilog insertion, code layout, etc is  
done.

-Chris