Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

2008-02-14-PassManager.ll
; RUN: opt < %s -loop-unroll -loop-rotate -simplifycfg -disable-output
; PR2028
define i32 @test1() {
       ret i32 0
}