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Move `RegionTracker` to `region_infer` 

In terms of code organisation, this is a lot cleaner and allows
tighter access modifiers.
This commit is contained in:
Amanda Stjerna 2024-05-21 16:57:00 +02:00
parent 3bdcb9d436
commit 2e1e119ba1
2 changed files with 93 additions and 95 deletions
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95
compiler/rustc_borrowck/src/constraints/mod.rs
View File

@ -1,106 +1,13 @@
use crate::region_infer::RegionDefinition;
use crate::type_check::Locations;
use rustc_data_structures::graph::scc::{self, Sccs};
use rustc_index::{IndexSlice, IndexVec};
use rustc_middle::mir::ConstraintCategory;
use rustc_middle::ty::{RegionVid, TyCtxt, UniverseIndex, VarianceDiagInfo};
use rustc_middle::ty::{RegionVid, TyCtxt, VarianceDiagInfo};
use rustc_span::Span;
use std::fmt;
use std::ops::Index;
pub(crate) mod graph;
pub type ConstraintSccs = Sccs<RegionVid, ConstraintSccIndex, RegionTracker>;
/// An annotation for region graph SCCs that tracks
/// the values of its elements.
#[derive(Copy, Debug, Clone)]
pub struct RegionTracker {
/// The largest universe of a placeholder reached from this SCC.
/// This includes placeholders within this SCC.
max_placeholder_universe_reached: UniverseIndex,
/// The smallest universe index reachable form the nodes of this SCC.
min_reachable_universe: UniverseIndex,
/// The representative Region Variable Id for this SCC. We prefer
/// placeholders over existentially quantified variables, otherwise
/// it's the one with the smallest Region Variable ID.
pub representative: RegionVid,
/// Is the current representative a placeholder?
representative_is_placeholder: bool,
/// Is the current representative existentially quantified?
representative_is_existential: bool,
}
impl scc::Annotation for RegionTracker {
fn merge_scc(mut self, mut other: Self) -> Self {
// Prefer any placeholder over any existential
if other.representative_is_placeholder && self.representative_is_existential {
other.merge_min_max_seen(&self);
return other;
}
if self.representative_is_placeholder && other.representative_is_existential
|| (self.representative <= other.representative)
{
self.merge_min_max_seen(&other);
return self;
}
other.merge_min_max_seen(&self);
other
}
fn merge_reached(mut self, other: Self) -> Self {
// No update to in-component values, only add seen values.
self.merge_min_max_seen(&other);
self
}
}
impl RegionTracker {
pub fn new(rvid: RegionVid, definition: &RegionDefinition<'_>) -> Self {
let (representative_is_placeholder, representative_is_existential) = match definition.origin
{
rustc_infer::infer::NllRegionVariableOrigin::FreeRegion => (false, false),
rustc_infer::infer::NllRegionVariableOrigin::Placeholder(_) => (true, false),
rustc_infer::infer::NllRegionVariableOrigin::Existential { .. } => (false, true),
};
let placeholder_universe =
if representative_is_placeholder { definition.universe } else { UniverseIndex::ROOT };
Self {
max_placeholder_universe_reached: placeholder_universe,
min_reachable_universe: definition.universe,
representative: rvid,
representative_is_placeholder,
representative_is_existential,
}
}
pub fn universe(self) -> UniverseIndex {
self.min_reachable_universe
}
fn merge_min_max_seen(&mut self, other: &Self) {
self.max_placeholder_universe_reached = std::cmp::max(
self.max_placeholder_universe_reached,
other.max_placeholder_universe_reached,
);
self.min_reachable_universe =
std::cmp::min(self.min_reachable_universe, other.min_reachable_universe);
}
/// Returns `true` if during the annotated SCC reaches a placeholder
/// with a universe larger than the smallest reachable one, `false` otherwise.
pub fn has_incompatible_universes(&self) -> bool {
self.universe().cannot_name(self.max_placeholder_universe_reached)
}
}
/// A set of NLL region constraints. These include "outlives"
/// constraints of the form `R1: R2`. Each constraint is identified by
/// a unique `OutlivesConstraintIndex` and you can index into the set

93
compiler/rustc_borrowck/src/region_infer/mod.rs
View File

@ -4,6 +4,7 @@ use std::rc::Rc;
use rustc_data_structures::binary_search_util;
use rustc_data_structures::frozen::Frozen;
use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
use rustc_data_structures::graph::scc::{self, Sccs};
use rustc_errors::Diag;
use rustc_hir::def_id::CRATE_DEF_ID;
use rustc_index::IndexVec;
@ -23,7 +24,6 @@ use rustc_mir_dataflow::points::DenseLocationMap;
use rustc_span::Span;
use crate::constraints::graph::{self, NormalConstraintGraph, RegionGraph};
use crate::constraints::{ConstraintSccs, RegionTracker};
use crate::dataflow::BorrowIndex;
use crate::{
constraints::{ConstraintSccIndex, OutlivesConstraint, OutlivesConstraintSet},
@ -46,6 +46,97 @@ mod reverse_sccs;
pub mod values;
pub type ConstraintSccs = Sccs<RegionVid, ConstraintSccIndex, RegionTracker>;
/// An annotation for region graph SCCs that tracks
/// the values of its elements.
#[derive(Copy, Debug, Clone)]
pub struct RegionTracker {
/// The largest universe of a placeholder reached from this SCC.
/// This includes placeholders within this SCC.
max_placeholder_universe_reached: UniverseIndex,
/// The smallest universe index reachable form the nodes of this SCC.
min_reachable_universe: UniverseIndex,
/// The representative Region Variable Id for this SCC. We prefer
/// placeholders over existentially quantified variables, otherwise
/// it's the one with the smallest Region Variable ID.
representative: RegionVid,
/// Is the current representative a placeholder?
representative_is_placeholder: bool,
/// Is the current representative existentially quantified?
representative_is_existential: bool,
}
impl scc::Annotation for RegionTracker {
fn merge_scc(mut self, mut other: Self) -> Self {
// Prefer any placeholder over any existential
if other.representative_is_placeholder && self.representative_is_existential {
other.merge_min_max_seen(&self);
return other;
}
if self.representative_is_placeholder && other.representative_is_existential
|| (self.representative <= other.representative)
{
self.merge_min_max_seen(&other);
return self;
}
other.merge_min_max_seen(&self);
other
}
fn merge_reached(mut self, other: Self) -> Self {
// No update to in-component values, only add seen values.
self.merge_min_max_seen(&other);
self
}
}
impl RegionTracker {
fn new(rvid: RegionVid, definition: &RegionDefinition<'_>) -> Self {
let (representative_is_placeholder, representative_is_existential) = match definition.origin
{
rustc_infer::infer::NllRegionVariableOrigin::FreeRegion => (false, false),
rustc_infer::infer::NllRegionVariableOrigin::Placeholder(_) => (true, false),
rustc_infer::infer::NllRegionVariableOrigin::Existential { .. } => (false, true),
};
let placeholder_universe =
if representative_is_placeholder { definition.universe } else { UniverseIndex::ROOT };
Self {
max_placeholder_universe_reached: placeholder_universe,
min_reachable_universe: definition.universe,
representative: rvid,
representative_is_placeholder,
representative_is_existential,
}
}
fn universe(self) -> UniverseIndex {
self.min_reachable_universe
}
fn merge_min_max_seen(&mut self, other: &Self) {
self.max_placeholder_universe_reached = std::cmp::max(
self.max_placeholder_universe_reached,
other.max_placeholder_universe_reached,
);
self.min_reachable_universe =
std::cmp::min(self.min_reachable_universe, other.min_reachable_universe);
}
/// Returns `true` if during the annotated SCC reaches a placeholder
/// with a universe larger than the smallest reachable one, `false` otherwise.
pub fn has_incompatible_universes(&self) -> bool {
self.universe().cannot_name(self.max_placeholder_universe_reached)
}
}
pub struct RegionInferenceContext<'tcx> {
pub var_infos: VarInfos,