Merge pull request #9 from TrevorHansen/om

An extra bottom-up recursive extractor

plot.py

@@ -65,6 +65,9 @@ def process(js, extractors):
     print(f"cumulative dag cost for {e1}: {sum(d[e1]['dag'] for d in by_name.values()):.0f}")
     print(f"cumulative dag cost for {e2}: {sum(d[e2]['dag'] for d in by_name.values()):.0f}")
 
+    print(f"Cumulative time for {e1}: {e1_cumulative/1000:.0f}ms")
+    print(f"Cumulative time for {e2}: {e2_cumulative/1000:.0f}ms")
+
     print(f"{e1} / {e2}")
 
     print("geo mean")

src/extract/faster_bottom_up.rs

@@ -1,3 +1,5 @@
+use rustc_hash::{FxHashMap, FxHashSet};
+
 use super::*;
 
 /// A faster bottom up extractor inspired by the faster-greedy-dag extractor.
@@ -16,7 +18,7 @@ pub struct BottomUpExtractor;
 
 impl Extractor for BottomUpExtractor {
     fn extract(&self, egraph: &EGraph, _roots: &[ClassId]) -> ExtractionResult {
-        let mut parents = IndexMap::<ClassId, Vec<NodeId>>::default();
+        let mut parents = IndexMap::<ClassId, Vec<NodeId>>::with_capacity(egraph.classes().len());
         let n2c = |nid: &NodeId| egraph.nid_to_cid(nid);
         let mut analysis_pending = UniqueQueue::default();
 
@@ -39,20 +41,20 @@ impl Extractor for BottomUpExtractor {
         }
 
         let mut result = ExtractionResult::default();
-        let mut costs = IndexMap::<ClassId, Cost>::default();
+        let mut costs = FxHashMap::<ClassId, Cost>::with_capacity_and_hasher(
+            egraph.classes().len(),
+            Default::default(),
+        );
 
         while let Some(node_id) = analysis_pending.pop() {
             let class_id = n2c(&node_id);
             let node = &egraph[&node_id];
-            if node.children.iter().all(|c| costs.contains_key(n2c(c))) {
-                let prev_cost = costs.get(class_id).unwrap_or(&INFINITY);
-
-                let cost = result.node_sum_cost(egraph, node, &costs);
-                if cost < *prev_cost {
-                    result.choose(class_id.clone(), node_id.clone());
-                    costs.insert(class_id.clone(), cost);
-                    analysis_pending.extend(parents[class_id].iter().cloned());
-                }
+            let prev_cost = costs.get(class_id).unwrap_or(&INFINITY);
+            let cost = result.node_sum_cost(egraph, node, &costs);
+            if cost < *prev_cost {
+                result.choose(class_id.clone(), node_id.clone());
+                costs.insert(class_id.clone(), cost);
+                analysis_pending.extend(parents[class_id].iter().cloned());
             }
         }
 
@@ -64,15 +66,15 @@ impl Extractor for BottomUpExtractor {
 
 Notably, insert/pop operations have O(1) expected amortized runtime complexity.
 
-Thanks Trevor for the implementation!
+Thanks @Bastacyclop for the implementation!
 */
 #[derive(Clone)]
 #[cfg_attr(feature = "serde-1", derive(Serialize, Deserialize))]
 pub(crate) struct UniqueQueue<T>
 where
     T: Eq + std::hash::Hash + Clone,
 {
-    set: std::collections::HashSet<T>, // hashbrown::
+    set: FxHashSet<T>, // hashbrown::
     queue: std::collections::VecDeque<T>,
 }
 
@@ -82,7 +84,7 @@ where
 {
     fn default() -> Self {
         UniqueQueue {
-            set: std::collections::HashSet::default(),
+            set: Default::default(),
             queue: std::collections::VecDeque::new(),
         }
     }

src/extract/mod.rs

@@ -1,3 +1,5 @@
+use indexmap::IndexMap;
+use rustc_hash::FxHashMap;
 use std::collections::HashMap;
 
 pub use crate::*;
@@ -22,6 +24,37 @@ pub trait Extractor: Sync {
     }
 }
 
+pub trait MapGet<K, V> {
+    fn get(&self, key: &K) -> Option<&V>;
+}
+
+impl<K, V> MapGet<K, V> for HashMap<K, V>
+where
+    K: Eq + std::hash::Hash,
+{
+    fn get(&self, key: &K) -> Option<&V> {
+        HashMap::get(self, key)
+    }
+}
+
+impl<K, V> MapGet<K, V> for FxHashMap<K, V>
+where
+    K: Eq + std::hash::Hash,
+{
+    fn get(&self, key: &K) -> Option<&V> {
+        FxHashMap::get(self, key)
+    }
+}
+
+impl<K, V> MapGet<K, V> for IndexMap<K, V>
+where
+    K: Eq + std::hash::Hash,
+{
+    fn get(&self, key: &K) -> Option<&V> {
+        IndexMap::get(self, key)
+    }
+}
+
 #[derive(Default, Clone)]
 pub struct ExtractionResult {
     pub choices: IndexMap<ClassId, NodeId>,
@@ -118,12 +151,10 @@ impl ExtractionResult {
         costs.values().sum()
     }
 
-    pub fn node_sum_cost(
-        &self,
-        egraph: &EGraph,
-        node: &Node,
-        costs: &IndexMap<ClassId, Cost>,
-    ) -> Cost {
+    pub fn node_sum_cost<M>(&self, egraph: &EGraph, node: &Node, costs: &M) -> Cost
+    where
+        M: MapGet<ClassId, Cost>,
+    {
         node.cost
             + node
                 .children

src/main.rs

@@ -20,6 +20,10 @@ fn main() {
 
     let extractors: IndexMap<&str, Box<dyn Extractor>> = [
         ("bottom-up", extract::bottom_up::BottomUpExtractor.boxed()),
+        (
+            "faster-bottom-up",
+            extract::faster_bottom_up::BottomUpExtractor.boxed(),
+        ),
         (
             "greedy-dag",
             extract::greedy_dag::GreedyDagExtractor.boxed(),