[llvm] [RegisterCoalescer] Avoid retrying high-cost joins for live intervals (PR #207976)

[Mingjie Xu via llvm-commits]

Enna1 wrote:

llvm-opt-benchmark-nightly focuses on middle-end optimizations, so this patch would not show any difference there.

Impact on compile-time-tracker is here: https://llvm-compile-time-tracker.com/compare.php?from=4708581453ead90685a55e343cc5ace1e1ddabb1&to=38a20d7fc82166b9c4dd0f46d7f2c78a9243c80b&stat=instructions:u



https://github.com/llvm/llvm-project/pull/207976