fn estimate_dataflow_backedges(
dependencies: &LocalDependencyIndex,
roots: &FxHashSet<Local>,
local_summary: &LoopLocalSummary,
) -> Option<usize>Expand description
Estimate how far loop-carried state must travel before reaching a sink.
This uses the whole-function local dependency graph, but only increments the distance when the dependency path crosses a state local for the current SCC. Temporaries introduced by calls/casts/projections therefore do not inflate the estimate.