clean up emit_drop_facts

- remove dependency on `TypeChecker`
- move to legacy fact generation module
- remove polonius module from liveness

Author: lqd

compiler/rustc_borrowck/src/polonius/legacy/mod.rs

@@ -3,15 +3,16 @@
 //! Will be removed in the future, once the in-tree `-Zpolonius=next` implementation reaches feature
 //! parity.
 
-use rustc_middle::mir::{Body, LocalKind, Location, START_BLOCK};
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::mir::{Body, Local, LocalKind, Location, START_BLOCK};
+use rustc_middle::ty::{GenericArg, TyCtxt};
 use rustc_mir_dataflow::move_paths::{InitKind, InitLocation, MoveData};
 use tracing::debug;
 
 use crate::borrow_set::BorrowSet;
 use crate::facts::{AllFacts, PoloniusRegionVid};
 use crate::location::LocationTable;
 use crate::type_check::free_region_relations::UniversalRegionRelations;
+use crate::universal_regions::UniversalRegions;
 
 mod accesses;
 mod loan_invalidations;
@@ -185,3 +186,22 @@ fn emit_cfg_and_loan_kills_facts<'tcx>(
 ) {
     loan_kills::emit_loan_kills(tcx, all_facts, location_table, body, borrow_set);
 }
+
+/// For every potentially drop()-touched region `region` in `local`'s type
+/// (`kind`), emit a `drop_of_var_derefs_origin(local, origin)` fact.
+pub(crate) fn emit_drop_facts<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    local: Local,
+    kind: &GenericArg<'tcx>,
+    universal_regions: &UniversalRegions<'tcx>,
+    all_facts: &mut Option<AllFacts>,
+) {
+    debug!("emit_drop_facts(local={:?}, kind={:?}", local, kind);
+    if let Some(facts) = all_facts.as_mut() {
+        let _prof_timer = tcx.prof.generic_activity("polonius_fact_generation");
+        tcx.for_each_free_region(kind, |drop_live_region| {
+            let region_vid = universal_regions.to_region_vid(drop_live_region);
+            facts.drop_of_var_derefs_origin.push((local, region_vid.into()));
+        });
+    }
+}

compiler/rustc_borrowck/src/type_check/liveness/mod.rs

@@ -13,11 +13,11 @@ use tracing::debug;
 
 use super::TypeChecker;
 use crate::constraints::OutlivesConstraintSet;
+use crate::polonius;
 use crate::region_infer::values::LivenessValues;
 use crate::universal_regions::UniversalRegions;
 
 mod local_use_map;
-mod polonius;
 mod trace;
 
 /// Combines liveness analysis with initialization analysis to
@@ -45,7 +45,7 @@ pub(super) fn generate<'a, 'tcx>(
     let (relevant_live_locals, boring_locals) =
         compute_relevant_live_locals(typeck.tcx(), &free_regions, body);
 
-    crate::polonius::legacy::emit_access_facts(
+    polonius::legacy::emit_access_facts(
         typeck.tcx(),
         body,
         move_data,

compiler/rustc_borrowck/src/type_check/liveness/polonius.rs

@@ -15,9 +15,9 @@ use rustc_trait_selection::traits::query::type_op::{DropckOutlives, TypeOp, Type
 use tracing::debug;
 
 use crate::location::RichLocation;
+use crate::polonius;
 use crate::region_infer::values::{self, LiveLoans};
 use crate::type_check::liveness::local_use_map::LocalUseMap;
-use crate::type_check::liveness::polonius;
 use crate::type_check::{NormalizeLocation, TypeChecker};
 
 /// This is the heart of the liveness computation. For each variable X
@@ -590,7 +590,13 @@ impl<'tcx> LivenessContext<'_, '_, '_, 'tcx> {
         // the destructor and must be live at this point.
         for &kind in &drop_data.dropck_result.kinds {
             Self::make_all_regions_live(self.elements, self.typeck, kind, live_at);
-            polonius::emit_drop_facts(self.typeck, dropped_local, &kind);
+            polonius::legacy::emit_drop_facts(
+                self.typeck.tcx(),
+                dropped_local,
+                &kind,
+                self.typeck.universal_regions,
+                self.typeck.all_facts,
+            );
         }
     }