[llvm] [RFC] implement convergence control in MIR using SelectionDAG (PR #71785)

[Sameer Sahasrabuddhe via llvm-commits]

ssahasra wrote:

Pushed a commit that elevates CONVERGENCECTRL_GLUE to be a target-independent opcode. This is much simpler because handling tokens no longer needs target callbacks and also does not need post-isel adjustment hook on convergent operations.

https://github.com/llvm/llvm-project/pull/71785