Struct spirt::cfg::Structurizer

pub struct Structurizer<'a> {
    cx: &'a Context,
    type_bool: Type,
    const_true: Const,
    const_false: Const,
    func_def_body: &'a mut FuncDefBody,
    loop_header_to_exit_targets: IndexMap<ControlRegion, IndexSet<ControlRegion, BuildHasherDefault<FxHasher>>, BuildHasherDefault<FxHasher>>,
    incoming_edge_counts_including_loop_exits: EntityOrientedDenseMap<ControlRegion, IncomingEdgeCount>,
    structurize_region_state: IndexMap<ControlRegion, StructurizeRegionState, BuildHasherDefault<FxHasher>>,
    control_region_input_replacements: EntityOrientedDenseMap<ControlRegion, SmallVec<[Value; 2]>>,
}

Control-flow “structurizer”, which attempts to convert as much of the CFG as possible into structural control-flow (regions).

See StructurizeRegionState’s docs for more details on the algorithm.

Fields

cx: &'a Context

type_bool: Type

Scrutinee type for SelectionKind::BoolCond.

const_true: Const

Scrutinee value for SelectionKind::BoolCond, for the “then” case.

const_false: Const

Scrutinee value for SelectionKind::BoolCond, for the “else” case.

func_def_body: &'a mut FuncDefBody

loop_header_to_exit_targets: IndexMap<ControlRegion, IndexSet<ControlRegion, BuildHasherDefault<FxHasher>>, BuildHasherDefault<FxHasher>>

incoming_edge_counts_including_loop_exits: EntityOrientedDenseMap<ControlRegion, IncomingEdgeCount>

structurize_region_state: IndexMap<ControlRegion, StructurizeRegionState, BuildHasherDefault<FxHasher>>

Keyed by the input to structurize_region_from (the start ControlRegion), and describing the state of that partial structurization step.

See also StructurizeRegionState’s docs.

control_region_input_replacements: EntityOrientedDenseMap<ControlRegion, SmallVec<[Value; 2]>>

Accumulated replacements (caused by target_inputss), i.e.: Value::ControlRegionInput { region, input_idx } must be replaced with control_region_input_replacements[region][input_idx], as the original region cannot have be directly reused.

Implementations

impl<'a> Structurizer<'a>

pub fn new(cx: &'a Context, func_def_body: &'a mut FuncDefBody) -> Self

pub fn structurize_func(self)

fn apply_value_replacements(self)

The last step of structurization is processing bulk replacements collected while structurizing (like control_region_input_replacements).

fn claim_or_defer_single_edge( &mut self, target: ControlRegion, target_inputs: SmallVec<[Value; 2]> ) -> PartialControlRegion

fn try_claim_edge_bundle( &mut self, edge_bundle: IncomingEdgeBundle<ControlRegion> ) -> Result<PartialControlRegion, DeferredEdgeBundle<ControlRegion>>

fn structurize_region_from(&mut self, unstructured_region: ControlRegion)

Structurize a region starting from unstructured_region, and extending it (by combining the smaller ControlRegions) as much as possible into the CFG (likely everything dominated by unstructured_region).

The output of this process is stored in, and any other bookkeeping is done through, self.structurize_region_state[unstructured_region].

See also StructurizeRegionState’s docs.

fn structurize_select( &mut self, kind: SelectionKind, scrutinee: Value, cases: SmallVec<[PartialControlRegion; 8]> ) -> PartialControlRegion

Build a Select ControlNode, from partially structured cases, merging all of their deferred_{edges,returns} together.

fn materialize_lazy_cond(&mut self, cond: LazyCond) -> Value

fn repair_unclaimed_region( &mut self, unstructured_region: ControlRegion, partial_control_region: PartialControlRegion )

When structurization is only partial, and there remain unclaimed regions, they have to be reintegrated into the CFG, putting back ControlInsts where structurize_region_from has taken them from.

This function handles one region at a time to make it more manageable, despite it having a single call site (in a loop in structurize_func).

fn const_undef(&self, ty: Type) -> Const

Create an undefined constant (as a placeholder where a value needs to be present, but won’t actually be used), of type ty.