From f6398b278c5542368faf1de748cc8c62dc1ba350 Mon Sep 17 00:00:00 2001
From: Julien Cretin <cretin@google.com>
Date: Mon, 28 May 2018 17:05:21 +0200
Subject: [PATCH] Return the errors in the naive algorithm

---
 polonius-engine/src/output/naive.rs | 34 ++++++++++++++++++++---------
 src/dump.rs                         | 14 ++++++------
 2 files changed, 31 insertions(+), 17 deletions(-)

diff --git a/polonius-engine/src/output/naive.rs b/polonius-engine/src/output/naive.rs
index f548c0c5bfd..424ad9aff4e 100644
--- a/polonius-engine/src/output/naive.rs
+++ b/polonius-engine/src/output/naive.rs
@@ -37,16 +37,19 @@ pub(super) fn compute<Region: Atom, Loan: Atom, Point: Atom>(
 
     let mut result = Output::new(dump_enabled);
 
-    let borrow_live_at_start = Instant::now();
+    let timer = Instant::now();
 
-    let borrow_live_at = {
+    let errors = {
         // Create a new iteration context, ...
         let mut iteration = Iteration::new();
 
         // .. some variables, ..
         let subset = iteration.variable::<(Region, Region, Point)>("subset");
         let requires = iteration.variable::<(Region, Loan, Point)>("requires");
-        let borrow_live_at = iteration.variable::<(Loan, Point)>("borrow_live_at");
+        let borrow_live_at = iteration.variable::<((Loan, Point), ())>("borrow_live_at");
+
+        // `invalidates` facts, stored ready for joins
+        let invalidates = iteration.variable::<((Loan, Point), ())>("invalidates");
 
         // different indices for `subset`.
         let subset_r1p = iteration.variable_indistinct("subset_r1p");
@@ -63,6 +66,9 @@ pub(super) fn compute<Region: Atom, Loan: Atom, Point: Atom>(
         let requires_1 = iteration.variable_indistinct("requires_1");
         let requires_2 = iteration.variable_indistinct("requires_2");
 
+        // output
+        let errors = iteration.variable("errors");
+
         let killed = all_facts.killed.into();
         let region_live_at = iteration.variable::<((Region, Point), ())>("region_live_at");
         let cfg_edge_p = iteration.variable::<(Point, Point)>("cfg_edge_p");
@@ -74,6 +80,9 @@ pub(super) fn compute<Region: Atom, Loan: Atom, Point: Atom>(
             all_facts.region_live_at.iter().map(|&(r, p)| ((r, p), ())),
         ));
         cfg_edge_p.insert(all_facts.cfg_edge.clone().into());
+        invalidates.insert(Relation::from(
+            all_facts.invalidates.iter().map(|&(p, b)| ((b, p), ())),
+        ));
 
         // .. and then start iterating rules!
         while iteration.changed() {
@@ -120,7 +129,12 @@ pub(super) fn compute<Region: Atom, Loan: Atom, Point: Atom>(
             requires.from_join(&requires_2, &region_live_at, |&(r, q), &b, &()| (r, b, q));
 
             // borrow_live_at(B, P) :- requires(R, B, P), region_live_at(R, P)
-            borrow_live_at.from_join(&requires_rp, &region_live_at, |&(_r, p), &b, &()| (b, p));
+            borrow_live_at.from_join(&requires_rp, &region_live_at, |&(_r, p), &b, &()| {
+                ((b, p), ())
+            });
+
+            // .decl errors(B, P) :- invalidates(B, P), borrow_live_at(B, P).
+            errors.from_join(&invalidates, &borrow_live_at, |&(b, p), &(), &()| (b, p));
         }
 
         if dump_enabled {
@@ -156,20 +170,20 @@ pub(super) fn compute<Region: Atom, Loan: Atom, Point: Atom>(
             }
         }
 
-        borrow_live_at.complete()
+        errors.complete()
     };
 
     if dump_enabled {
         println!(
-            "borrow_live_at is complete: {} tuples, {:?}",
-            borrow_live_at.len(),
-            borrow_live_at_start.elapsed()
+            "errors is complete: {} tuples, {:?}",
+            errors.len(),
+            timer.elapsed()
         );
     }
 
-    for (borrow, location) in &borrow_live_at.elements {
+    for (borrow, location) in &errors.elements {
         result
-            .borrow_live_at
+            .errors
             .entry(*location)
             .or_insert(Vec::new())
             .push(*borrow);
diff --git a/src/dump.rs b/src/dump.rs
index 0d62f9b9722..29f2f942333 100644
--- a/src/dump.rs
+++ b/src/dump.rs
@@ -14,9 +14,9 @@ crate fn dump_output(
     intern: &InternerTables,
 ) -> io::Result<()> {
     dump_rows(
-        &mut writer_for(output_dir, "borrow_live_at")?,
+        &mut writer_for(output_dir, "errors")?,
         intern,
-        &output.borrow_live_at,
+        &output.errors,
     )?;
 
     if output.dump_enabled {
@@ -40,11 +40,6 @@ crate fn dump_output(
             intern,
             &output.invalidates,
         )?;
-        dump_rows(
-            &mut writer_for(output_dir, "errors")?,
-            intern,
-            &output.errors,
-        )?;
         dump_rows(
             &mut writer_for(output_dir, "subset")?,
             intern,
@@ -55,6 +50,11 @@ crate fn dump_output(
             intern,
             &output.subset_anywhere,
         )?;
+        dump_rows(
+            &mut writer_for(output_dir, "borrow_live_at")?,
+            intern,
+            &output.borrow_live_at,
+        )?;
     }
     return Ok(());