Struct rustc_mir::transform::dest_prop::Conflicts

struct Conflicts<'a> {
    relevant_locals: &'a BitSet<Local>,
    matrix: BitMatrix<Local, Local>,
    unify_cache: BitSet<Local>,
    unified_locals: InPlaceUnificationTable<UnifyLocal>,
}

Fields

relevant_locals: &'a BitSet<Local>

matrix: BitMatrix<Local, Local>

The conflict matrix. It is always symmetric and the adjacency matrix of the corresponding conflict graph.

unify_cache: BitSet<Local>

Preallocated BitSet used by unify.

unified_locals: InPlaceUnificationTable<UnifyLocal>

Tracks locals that have been merged together to prevent cycles and propagate conflicts.

Implementations

impl<'a> Conflicts<'a>

fn build<'tcx>(
    tcx: TyCtxt<'tcx>,
    body: &Body<'tcx>,
    relevant_locals: &'a BitSet<Local>
) -> Self

fn record_dataflow_conflicts(&mut self, new_conflicts: &mut BitSet<Local>)

fn record_local_conflict(&mut self, a: Local, b: Local, why: &str)

fn record_statement_conflicts(&mut self, stmt: &Statement<'_>)

Records locals that must not overlap during the evaluation of stmt. These locals conflict and must not be merged.

fn record_terminator_conflicts(&mut self, term: &Terminator<'_>)

fn can_unify(&mut self, a: Local, b: Local) -> bool

Checks whether a and b may be merged. Returns false if there’s a conflict.

fn unify(&mut self, a: Local, b: Local)

Merges the conflicts of a and b, so that each one inherits all conflicts of the other.

can_unify must have returned true for the same locals, or this may panic or lead to miscompiles.

This is called when the pass makes the decision to unify a and b (or parts of a and b) and is needed to ensure that future unification decisions take potentially newly introduced conflicts into account.

For an example, assume we have locals _0, _1, _2, and _3. There are these conflicts:

• _0 <-> _1
• _1 <-> _2
• _3 <-> _0

We then decide to merge _2 with _3 since they don’t conflict. Then we decide to merge _2 with _0, which also doesn’t have a conflict in the above list. However _2 is now _3, which does conflict with _0.