Struct rustc_mir_build::build::scope::DropTree

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struct DropTree {
    drops: IndexVec<DropIdx, DropNode>,
    existing_drops_map: FxHashMap<DropNodeKey, DropIdx>,
    entry_points: Vec<(DropIdx, BasicBlock)>,
}
Expand description

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

  • Drops on unwind paths
  • Drops on coroutine drop paths (when a suspended coroutine is dropped)
  • Drops on return and loop exit paths
  • Drops on the else path in an if let chain

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

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§drops: IndexVec<DropIdx, DropNode>

Nodes in the drop tree, containing drop data and a link to the next node.

§existing_drops_map: FxHashMap<DropNodeKey, DropIdx>

Map for finding the index of an existing node, given its contents.

§entry_points: Vec<(DropIdx, BasicBlock)>

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

Implementations§

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impl DropTree

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fn new() -> Self

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

Adds a node to the drop tree, consisting of drop data and the index of the “next” drop (in drop order), which could be the sentinel ROOT_NODE.

If there is already an equivalent node in the tree, nothing is added, and that node’s index is returned. Otherwise, the new node’s index is returned.

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

Registers from as an entry point to this drop tree, at to.

During Self::build_mir, from will be linked to the corresponding block within the drop tree.

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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.

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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.

Trait Implementations§

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impl Debug for DropTree

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

Formats the value using the given formatter. Read more

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Size: 80 bytes