Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

ret.ll
; Runs original SDAG test with -global-isel
; RUN: llc -global-isel -march=amdgcn -mcpu=tahiti -verify-machineinstrs < %S/../ret.ll | FileCheck -check-prefix=GCN %S/../ret.ll
; RUN: llc -global-isel -march=amdgcn -mcpu=tonga -verify-machineinstrs < %S/../ret.ll | FileCheck -check-prefix=GCN %S/../ret.ll