Currently, there is significant code duplication for dealing with
MD_prof metadata throughout the compiler. These utility functions can
improve code reuse and simplify boilerplate code when dealing with
profiling metadata, such as branch weights. The inent is to provide a
uniform set of APIs that allow common tasks, such as identifying
specific types of MD_prof metadata and extracting branch weights.
Future patches can build on this initial implementation and clean up the
different implementations across the compiler.
Reviewed By: bogner
Differential Revision: https://reviews.llvm.org/D128858
