Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

i128-and-beyond.ll
; RUN: llc -verify-machineinstrs < %s -mtriple=ppc32-- | grep 4294967295 | count 28

; These static initializers are too big to hand off to assemblers
; as monolithic blobs.

@x = global i128 -1
@y = global i256 -1
@z = global i512 -1