Struct rustc_mir_build::build::scope::DropTree

struct DropTree {
    drops: IndexVec<DropIdx, (DropData, DropIdx)>,
    previous_drops: FxHashMap<(DropIdx, Local, DropKind), DropIdx>,
    entry_points: Vec<(DropIdx, BasicBlock)>,
}

A tree of drops that we have deferred lowering. It’s used for:

• Drops on unwind paths
• Drops on generator drop paths (when a suspended generator is dropped)
• Drops on return and loop exit paths

Once no more nodes could be added to the tree, we lower it to MIR in one go in build_mir.

Fields

drops: IndexVec<DropIdx, (DropData, DropIdx)>

Drops in the tree.

previous_drops: FxHashMap<(DropIdx, Local, DropKind), DropIdx>

Map for finding the inverse of the next_drop relation:

previous_drops[(drops[i].1, drops[i].0.local, drops[i].0.kind)] == i

entry_points: Vec<(DropIdx, BasicBlock)>

Edges into the DropTree that need to be added once it’s lowered.

Implementations

impl DropTree

fn new() -> Self

fn add_drop(&mut self, drop: DropData, next: DropIdx) -> DropIdx

fn add_entry(&mut self, from: BasicBlock, to: DropIdx)

fn build_mir<'tcx, T: DropTreeBuilder<'tcx>>(
    &mut self,
    cfg: &mut CFG<'tcx>,
    blocks: &mut IndexVec<DropIdx, Option<BasicBlock>>
)

Builds the MIR for a given drop tree.

blocks should have the same length as self.drops, and may have its first value set to some already existing block.

fn assign_blocks<'tcx, T: DropTreeBuilder<'tcx>>(
    &mut self,
    cfg: &mut CFG<'tcx>,
    blocks: &mut IndexVec<DropIdx, Option<BasicBlock>>
)

Assign blocks for all of the drops in the drop tree that need them.

fn link_blocks<'tcx>(
    &self,
    cfg: &mut CFG<'tcx>,
    blocks: &IndexVec<DropIdx, Option<BasicBlock>>
)

Trait Implementations

impl Debug for DropTree

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.