The pass works in two modes:
Mode 1: Just set attributes starting from kernels. This can work at
the very beginning of opt and llc pipeline, but cannot clone functions
because it must be a function pass.
Mode 2: Actually clone functions for new attributes. This can only work
after all function passes in the opt pipeline because it has to be a
module pass.
Differential Revision: https://reviews.llvm.org/D63208
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363586 91177308-0d34-0410-b5e6-96231b3b80d8
