Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

legalize-bug-bogus-cpu.ll
; RUN: llc < %s -mtriple=aarch64-eabi -mcpu=bogus

; Fix the bug in PR20557. Set mcpu to a bogus name, llc will crash in type
; legalization.
define <4 x float> @fneg4(<4 x float> %x) {
  %sub = fsub <4 x float> zeroinitializer, %x
  ret <4 x float> %sub
}